CN111181370B - Switching power supply and control circuit and control method thereof - Google Patents

Switching power supply and control circuit and control method thereof Download PDF

Info

Publication number
CN111181370B
CN111181370B CN201911395751.7A CN201911395751A CN111181370B CN 111181370 B CN111181370 B CN 111181370B CN 201911395751 A CN201911395751 A CN 201911395751A CN 111181370 B CN111181370 B CN 111181370B
Authority
CN
China
Prior art keywords
signal
voltage
current
control
sampling
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201911395751.7A
Other languages
Chinese (zh)
Other versions
CN111181370A (en
Inventor
王建龙
熊毅
曹立丰
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hangzhou Silan Microelectronics Co Ltd
Original Assignee
Hangzhou Silan Microelectronics Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hangzhou Silan Microelectronics Co Ltd filed Critical Hangzhou Silan Microelectronics Co Ltd
Priority to CN201911395751.7A priority Critical patent/CN111181370B/en
Publication of CN111181370A publication Critical patent/CN111181370A/en
Application granted granted Critical
Publication of CN111181370B publication Critical patent/CN111181370B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
    • H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
    • H02H7/1213—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for DC-DC converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention discloses a switching power supply and a control circuit and a control method thereof, wherein the control circuit comprises a control unit, a threshold value adjusting unit, a first protection unit and a driving unit, the control unit is used for generating a first control signal and a target current signal, the threshold value adjusting unit obtains a first reference voltage representing a voltage limiting protection threshold value according to the target current signal, the current limiting protection threshold value of input current is adjusted in real time through detecting the load state, when the switching power supply works under different load conditions and fluctuates with a power grid, the input current can be ensured to be always kept below the set current limiting protection threshold value, a power device at the rear end is prevented from being overshot by larger current, the reliability of the switching power supply is improved, and the service life of the switching power supply is prolonged.

Description

Switching power supply and control circuit and control method thereof
Technical Field
The invention relates to the technical field of switching power supply control, in particular to a switching power supply and a control circuit and a control method thereof.
Background
A switching power supply is a power supply that maintains an output voltage stable by controlling a time ratio of on and off of a power switching tube using modern power electronic technology, and generally includes a Pulse Width Modulation (PWM) control circuit and a power switching tube (e.g., an IGBT (Insulated Gate Bipolar Transistor)). The conventional switching power supply is implemented in an analog control mode, a digital control mode and a digital-analog hybrid control mode. In recent years, digital control methods have become widely used and accepted because of their advantages such as programmability, design continuity, and a small number of components.
Due to the existence of nonlinear elements and energy storage elements in a large number of electric devices, the waveform of the alternating current input current is seriously distorted, and the input power factor of the power grid side is low. Therefore, a PFC (Power Factor Correction) control system must be added to the electric equipment. In a PFC control system, the on and off of a power switch tube are controlled through a PWM control signal to realize the control of a system power factor and an output voltage, meanwhile, the input current needs to be detected and protected in real time, and if the detected input current is higher than a set overcurrent protection threshold value, the power switch tube is closed in time to prevent the failure of the power switch tube and a rear-end device caused by overhigh input current.
The traditional PFC overcurrent protection can be divided into software protection and hardware protection, wherein the software protection comprises the steps of sending sampling voltage representing input current into a digital-analog sampling port of a microcontroller, then carrying out software filtering on a sampling result, and closing a power switch tube if a filtered value is higher than a set protection threshold value. In the hardware protection, a sampling voltage obtained according to the input current is compared with a reference voltage (namely an overcurrent protection threshold) set by hardware through a hardware comparator, and when the sampling voltage is higher than the reference voltage, the comparator is turned over, and the microcontroller closes the power switch tube.
In the actual working process of the switching power supply, if the rear end load is light, the input current is small, and conversely, if the rear end load is heavy, the input current is large. In the traditional PFC hardware overcurrent protection, because of the limitation that the overcurrent protection threshold value is not adjustable, the set protection threshold value needs to be larger than the input current when the switching power supply operates at the maximum power, and enough margin needs to be reserved to prevent false triggering. However, if the switching power supply often works in an environment with a light load and severe and frequent power grid fluctuation, input current overshoot will frequently occur, but since the hardware overcurrent protection point is set to be high, hardware overcurrent protection cannot be triggered, so that the power device at the rear end frequently bears too high input current, and the service lives of the power switching tube, the filter capacitor at the rear end, the load and the like are easily affected.
In addition, the overcurrent protection of the conventional PFC hardware easily causes the false triggering of the overcurrent protection when the transient input current is impacted or disturbed, which leads to unnecessary shutdown protection, and if the normal operation of the power supply cannot be recovered in time after shutdown, the output voltage at the rear end is reduced, even the operation of the rear end load is abnormal.
Disclosure of Invention
In view of the above, an object of the present invention is to provide a switching power supply, a control circuit and a control method thereof, which adjust a current-limiting protection threshold of an input current in real time by detecting a load state, so that when the switching power supply operates under different load conditions and encounters power grid fluctuation, the input current can be always kept below a set current-limiting protection threshold, a power device at a rear end is prevented from being overshot by a large current, reliability of the switching power supply is improved, and a service life of the switching power supply is prolonged.
According to a first aspect of embodiments of the present invention, there is provided a control circuit of a switching power supply, the control circuit including: an input current sampling unit which samples an input current to obtain a sampling voltage of the input current; a control unit generating a first control signal and a target current signal; the threshold adjusting unit is connected with the control unit and obtains a first reference voltage according to the target current signal; the first protection unit is connected with the control unit and outputs a second control signal according to the sampling voltage of the input current, the first reference voltage and the first control signal; and the driving unit is connected with the first protection unit, outputs a driving signal for controlling a power switch tube according to the second control signal, and turns off the power switch tube according to the second control signal when the sampling voltage of the input current is greater than or equal to the first reference voltage, wherein the threshold value adjusting unit adjusts the first reference voltage according to the load state of the switching power supply.
Preferably, the threshold value adjusting unit includes: the software adjusting module receives the target current signal and obtains a current-limiting protection threshold according to the target current signal; and the digital-to-analog conversion module is used for receiving the current-limiting protection threshold value and carrying out digital-to-analog conversion on the current-limiting protection threshold value to generate the first reference voltage.
Preferably, the software adjusting module obtains the current-limiting protection threshold according to a maximum value of the target current signal, an amplitude of a current ripple, and a preset first protection margin.
Preferably, the control circuit further comprises: an input voltage sampling unit which samples an input voltage of the switching power supply to obtain a sampling voltage of the input voltage; and the control unit generates the first control signal and the target current signal according to the sampling voltage of the input current, the target voltage, the sampling voltage of the input voltage and the sampling voltage of the output voltage.
Preferably, the control unit includes: a duty signal generation unit that generates a duty signal from the sampling voltage of the input current, the sampling voltage of the input voltage, the sampling voltage of the output voltage, and the target voltage; and a PWM generating unit generating the first control signal and a PWM reset signal according to the duty signal, wherein the duty signal generating unit includes: the first adding module is used for obtaining a first error according to the sampling voltage of the output voltage and the target voltage; the first linear control module is used for obtaining an input current effective value according to the first error; the phase calculation module is used for obtaining an input voltage phase value according to the sampling voltage of the input voltage; the multiplication module is used for obtaining a target current signal according to the input current effective value and the input voltage phase value; the second addition module is used for obtaining a second error according to the sampling voltage of the input current and the target current signal; and a second linear control module generating the duty cycle signal according to the second error.
Preferably, the first linear control module and the second linear control module each include a PI controller.
Preferably, the first protection unit includes: the comparison module compares the first reference voltage with the sampling voltage of the input current and generates a first indication signal according to a comparison result; the fault management module is connected with the comparison module and generates the second control signal according to the first indication signal, the first control signal and the PWM reset signal; when the sampling voltage of the input current is larger than or equal to the first reference voltage, judging that the input current is over-current, outputting the second control signal by the fault management module to turn off the power switch tube, and outputting the second control signal by the fault management module according to the PWM reset signal to turn on the power switch tube in the next control period.
Preferably, the fault management module comprises: a first latch generating a first fail signal according to the PWM reset signal and the first indication signal; and the AND gate generates the second control signal according to the first control signal and the first fault signal, wherein when the first indication signal is valid, the first fault signal is valid, when the PWM reset signal is valid and the first indication signal is invalid, the first fault signal is invalid, when the first fault signal is invalid, the state of the second control signal is consistent with the state of the first control signal, and when the first fault signal is valid, the second control signal is invalid.
Preferably, the first protection unit is further configured to control the driving unit to turn off the power switch tube when the number of times that the sampled voltage of the input current is greater than or equal to the first reference voltage within a first preset time reaches a preset value and a fault clearing signal is not received.
Preferably, the first protection unit further includes: the second indication signal generation unit is used for counting the first indication signal, obtaining a count value, generating a second indication signal according to the count value, and enabling the second indication signal to be effective when the count value is greater than or equal to a preset value within a first preset time, wherein the second indication signal generation unit comprises: the counting module is used for counting the first indicating signal to obtain a counting value, generating an intermediate indicating signal according to the counting value, and enabling the intermediate indicating signal to be effective when the counting value is larger than or equal to a preset value within first preset time; the latch module is connected with the counting module and used for latching the intermediate indication signal and generating a second indication signal according to the intermediate indication signal; the first timer is used for repeatedly timing, generating a counting reset signal after the first preset time, resetting the counting value according to the counting reset signal by the counting module and restarting counting; and the second timer starts timing when the intermediate indication signal is effective and generates a fault clearing signal after a second preset time, and the latch module generates a second indication signal according to the fault clearing signal and the intermediate indication signal.
Preferably, the fault management module further comprises: and a second latch configured to generate a second fail signal based on the PWM reset signal and the second indication signal, wherein the second fail signal is enabled when the second indication signal is enabled, the second fail signal is disabled when the PWM reset signal is enabled and the second indication signal is disabled, a state of the second control signal is identical to a state of the first control signal when both the first fail signal and the second fail signal are disabled, and the second control signal is disabled when one of the first fail signal and the second fail signal is enabled.
Preferably, the control circuit further includes a load state detection unit that detects a load state of the switching power supply to obtain the target voltage, the target voltage varying according to a variation in the load state.
Preferably, the control circuit further includes a hardware protection unit, which receives a sampling voltage of the input current, the hardware protection unit generates a first trigger signal when the sampling voltage of the input current is greater than or equal to a second reference voltage, the driving unit turns off the power switching tube according to the first trigger signal, and the control unit controls the first control signal to be in an invalid state according to the first trigger signal, where the second reference voltage represents a first overcurrent protection threshold, and the second reference voltage is greater than the first reference voltage.
Preferably, the control circuit further includes a software protection unit, which receives a sampling voltage of the input current, the third protection unit generates a second trigger signal when the sampling voltage of the input current is greater than or equal to a third reference voltage, and the control unit controls the first control signal to be in an invalid state according to the first trigger signal, where the third reference voltage represents a second overcurrent protection threshold, and the first reference voltage is greater than the third reference voltage.
Preferably, the threshold adjusting unit is further configured to obtain the second overcurrent protection threshold according to the target current signal.
Preferably, the threshold value adjusting unit includes: and the software adjusting module is used for receiving the target current signal and obtaining the second overcurrent protection threshold according to the maximum value of the target current signal, the amplitude of the current ripple and a preset second protection margin.
According to a second aspect of the embodiments of the present invention, there is provided a switching power supply including the control circuit described above.
Preferably, the switching power supply further includes: a rectifier bridge rectifying an alternating input voltage to obtain the input voltage; the inductor, the diode and the sampling resistor are connected to two ends of the rectifier bridge in series, and the anode of the diode is connected with the power switch tube and the middle node of the inductor; and the output capacitor is connected between the intermediate node and the cathode of the diode and used for stabilizing the output voltage.
According to a third aspect of the embodiments of the present invention, there is provided a control method of a switching power supply, the control method including: sampling the input current to obtain a sampled voltage of the input current; generating a first control signal and a target current signal; obtaining a first reference voltage according to the target current signal; outputting a second control signal according to the sampling voltage of the input current, the first reference voltage and the first control signal; and outputting a driving signal for controlling a power switch tube according to the second control signal, and when the sampling voltage of the input current is greater than or equal to the first reference voltage, the driving unit turns off the power switch tube according to the second control signal, wherein the control method further comprises adjusting the first reference voltage according to the load state of the switching power supply.
Preferably, the step of obtaining a first reference voltage according to the target current signal includes: receiving the target current signal, and obtaining a current-limiting protection threshold value according to the target current signal; and performing digital-to-analog conversion on the current-limiting protection threshold value to generate the first reference voltage.
Preferably, the step of obtaining the current-limiting protection threshold according to the target current signal includes: and obtaining the current-limiting protection threshold according to the maximum value of the target current signal, the amplitude of the current ripple and a preset first protection margin.
Preferably, the control method further includes: sampling an input voltage of the switching power supply to obtain a sampled voltage of the input voltage; sampling an output voltage of the switching power supply to obtain a sampled voltage of the output voltage; and generating the first control signal and the target current signal according to the sampling voltage of the input current, the target voltage, the sampling voltage of the input voltage and the sampling voltage of the output voltage.
Preferably, the step of generating the first control signal and the target current signal according to the sampled voltage of the input current, the target voltage, the sampled voltage of the input voltage, and the sampled voltage of the output voltage includes: generating a duty cycle signal according to the sampling voltage of the input current, the sampling voltage of the input voltage, the sampling voltage of the output voltage and the target voltage; and generating the first control signal and a PWM reset signal according to the duty signal, wherein the generating the duty signal according to the sampling voltage of the input current, the sampling voltage of the input voltage, the sampling voltage of the output voltage, and the target voltage includes: obtaining a first error according to the sampling voltage of the output voltage and the target voltage; obtaining an input current effective value according to the first error; obtaining an input voltage phase value according to the sampling voltage of the input voltage; obtaining a target current signal according to the input current effective value and the input voltage phase value; obtaining a second error according to the sampling voltage of the input current and the target current signal; and generating the duty cycle signal according to the second error.
Preferably, the step of outputting a second control signal according to the sampled voltage of the input current, the first reference voltage, and the first control signal includes: comparing the first reference voltage with the sampling voltage of the input current, and generating a first indication signal according to the comparison result; generating the second control signal according to the first indication signal, the first control signal and a PWM reset signal; when the sampling voltage of the input current is larger than or equal to the first reference voltage, judging that the input current is over-current, outputting the second control signal to turn off the power switch tube, and outputting the second control signal to turn on the power switch tube according to the PWM reset signal in the next control period.
Preferably, the step of generating the second control signal according to the first indication signal, the first control signal and a PWM reset signal includes: generating a first fault signal according to the PWM reset signal and the first indication signal; and generating the second control signal according to the first control signal and the first fault signal, wherein when the first indication signal is valid, the first fault signal is valid, when the PWM reset signal is valid and the first indication signal is invalid, the first fault signal is invalid, when the first fault signal is invalid, the state of the second control signal is consistent with the state of the first control signal, and when the first fault signal is valid, the second control signal is invalid.
Preferably, the control method further includes: and when the times that the sampling voltage of the input current is greater than or equal to the first reference voltage within the first preset time reaches a preset value and a fault clearing signal is not received, the power switch tube is turned off.
Preferably, the step of generating a second control signal according to the sampled voltage of the input current, a first reference voltage and the first control signal further comprises: counting the first indicating signal to obtain a counting value, generating an intermediate indicating signal according to the counting value, and enabling the intermediate indicating signal to be effective when the counting value is larger than or equal to a preset value within first preset time; latching the intermediate indication signal and generating a second indication signal according to the intermediate indication signal; generating a counting reset signal after the first preset time, resetting the counting value according to the counting reset signal, and restarting counting; starting timing when the intermediate indication signal is effective, generating a fault clearing signal after a second preset time, and generating a second indication signal according to the fault clearing signal and the intermediate indication signal; generating the second control signal according to the first indication signal, the second indication signal and the first control signal.
Preferably, the step of generating the second control signal according to the first indication signal, the second indication signal and the first control signal further comprises: and generating a second fault signal according to the PWM reset signal and the second indication signal, wherein the second fault signal is enabled when the second indication signal is enabled, the second fault signal is disabled when the PWM reset signal is enabled and the second indication signal is disabled, the state of the second control signal is consistent with the state of the first control signal when both the first fault signal and the second fault signal are disabled, and the second control signal is disabled when one of the first fault signal and the second fault signal is enabled.
Preferably, the control method further includes: the target voltage is obtained by detecting a load state of the switching power supply, and the target voltage changes according to a change of the load state.
Preferably, the control method further includes: and generating a first trigger signal when the sampling voltage of the input current is greater than or equal to a second reference voltage, turning off the power switch tube according to the first trigger signal, and controlling the first control signal to be in an invalid state, wherein the second reference voltage represents a first overcurrent protection threshold value, and the second reference voltage is greater than the first reference voltage.
Preferably, the control method further includes: and generating a second trigger signal when the sampling voltage of the input current is greater than or equal to a third reference voltage, and controlling the first control signal to be in an invalid state according to the first trigger signal, wherein the third reference voltage represents a second overcurrent protection threshold value, and the first reference voltage is greater than the third reference voltage.
Preferably, the control method further includes obtaining the second overcurrent protection threshold according to the target current signal.
Preferably, the step of obtaining the second overcurrent protection threshold according to the target current signal includes: and obtaining the second overcurrent protection threshold according to the maximum value of the target current signal, the amplitude of the current ripple and a preset second protection margin.
The switching power supply, the control circuit and the control method thereof have the following beneficial effects.
The switching power supply of the embodiment of the invention can modify the current-limiting protection threshold value in real time according to the load state, can ensure that the input current of the main circuit is always controlled within a certain range when the switching power supply works under different load conditions and meets the power grid fluctuation, prevents the input current from generating larger fluctuation, and protects devices such as a rear-end filter capacitor, a load and the like.
In a further embodiment, the switching power supply can adjust the overcurrent protection threshold of the software overcurrent protection in real time according to the load state, so that the safety and the stability of the switching power supply when the switching power supply encounters power grid fluctuation under different load conditions are further improved.
In a further embodiment, the switching power supply of the embodiment of the invention provides two-stage hardware overcurrent protection, when input current triggers overshoot due to certain external interference, the input current can be ensured to be always below a set current-limiting protection threshold, the current overshoot amplitude is reduced, frequent overcurrent impact on a filter capacitor, a load and the like at the rear end is avoided to the greatest extent, and the stability of a system and the service life of devices are improved. And even though accidental false triggering occurs, the power switch tube of the main circuit can be quickly opened in the next PWM control period, so that the condition that the output voltage is too low and the normal work of a power supply system is not influenced is prevented, the frequent shutdown of the system due to overcurrent protection can be avoided under the condition that the power grid fluctuates frequently and violently, and the user experience of related products is improved.
In a further embodiment, when the input current exceeds the current limiting protection threshold value for a plurality of times within a certain time, the switching power supply enters a single protection mode, and the switching power supply can be restarted only by clearing the protection mode flag bit through software, that is, the switching power supply can be restarted only by receiving a fault clearing signal. Even under the condition that frequent overcurrent is caused by frequent fluctuation of a power grid, the input current can be ensured to be always close to a set current-limiting protection threshold value for small-amplitude fluctuation, overvoltage impact on devices such as a filter capacitor and a load at the rear end is avoided to the greatest extent, and the stability of the system and the service life of the devices are improved.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.
Fig. 1 shows a schematic configuration diagram of a switching power supply according to a first embodiment of the present invention;
FIG. 2 shows a schematic diagram of the control unit of FIG. 1;
fig. 3 is a schematic diagram showing a structure of the duty signal generating unit in fig. 2;
FIG. 4 is a schematic diagram of the threshold adjusting unit of FIG. 1;
FIG. 5 is a schematic structural diagram of the first protection unit of FIG. 1;
FIG. 6 is a schematic diagram showing a structure of a second indication signal generation unit in FIG. 5;
FIG. 7 shows a schematic diagram of the structure of the fault management module of FIG. 5;
fig. 8 shows a schematic configuration diagram of a switching power supply according to a second embodiment of the present invention;
FIG. 9 is a schematic diagram showing the structure of the threshold adjusting unit in FIG. 8;
fig. 10 shows an operation timing diagram of the switching power supply according to the embodiment of the invention;
fig. 11 shows a waveform schematic diagram of overcurrent protection of a switching power supply according to the prior art and an embodiment of the invention;
fig. 12 shows a method flowchart of a control method of a switching power supply according to a third embodiment of the present invention;
fig. 13 is a detailed flowchart illustrating a control method according to a third embodiment of the present invention;
fig. 14 is a flowchart showing a cycle-by-cycle protection mode of the control method according to the third embodiment of the invention;
fig. 15 shows a flow chart of a single protection mode of the control method according to the third embodiment of the present invention.
Detailed Description
The invention will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by like reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale. Moreover, certain well-known elements may not be shown in the figures.
In the following description, numerous specific details of the invention, such as structure, materials, dimensions, processing techniques and techniques of components, are set forth in order to provide a more thorough understanding of the invention. However, as will be understood by those skilled in the art, the present invention may be practiced without these specific details.
It should be understood that in the following description, a "circuit" refers to a conductive loop formed by at least one element or sub-circuit through an electrical or electromagnetic connection. When an element or circuit is referred to as being "connected to" another element or element/circuit is referred to as being "connected between" two nodes, it may be directly coupled or connected to the other element or intervening elements may be present, and the connection between the elements may be physical, logical, or a combination thereof. In contrast, when an element is referred to as being "directly coupled" or "directly connected" to another element, it is intended that there are no intervening elements present.
Fig. 1 shows a schematic configuration diagram of a switching power supply according to a first embodiment of the present invention. The switching power supply of the embodiment adopts a Boost topology and works in a floating mode. Of course, the switching power supply of the embodiment of the invention can also be used in a Buck topology, a Boost-Buck topology and the like. As shown in fig. 1, the switching power supply includes a rectifier bridge 110, a main circuit 120, an output capacitor Cout, a load 130, and a control circuit 200. Wherein the input terminal of the main circuit 120 is connected to the output terminal of the rectifier bridge 110, and the output terminal is connected to the load 130. The main circuit 120 includes an inductor Lf, a power switch tube T1, a fast recovery diode VD, and a sampling resistor Rsen.
Further, the input end of the rectifier bridge 110 is connected to the AC power source AC, the rectifier bridge 110 is configured to convert an AC input signal into an input voltage Vin, the inductor Lf is connected in series with the power switch tube T1 and the sampling resistor Rsen between the positive output end and the negative output end of the rectifier bridge 110, the fast recovery diode VD mainly plays an isolation role, and prevents the output capacitor Cout from being shorted to ground when the power switch tube T1 is turned on, and the output capacitor Cout is connected in parallel with the load 130 and configured to stabilize the output voltage Vout. The control terminal of the power switch T1 is connected to the control circuit 200, and the control circuit 200 is used for controlling the power switch T1 to be turned on and off, so that the main circuit 120 obtains the output voltage Vout according to the input voltage Vin. During the on-time of the power switch T1, the AC power source AC charges the inductor Lf, and during the off-time of the power switch T1, the inductor Lf supplies power to the load 130. The control circuit 200 is further configured to detect the input current Iin in real time and perform overcurrent protection on the circuit, and if the detected input current Iin is higher than a set current limiting protection threshold or an overcurrent protection threshold, turn off the power switch transistor T1 in the main circuit 120 in time to prevent the input current Iin from being too high to cause failure of the power switch transistor T1 and the backend device.
Further, the power switch Transistor T1 in this embodiment is implemented by, for example, an IGBT (Metal-Oxide-Semiconductor Field-Effect Transistor) or a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). The IGBT is a composite voltage-driven power semiconductor device composed of BJT (Bipolar Junction Transistor) and MOSFET, and has the advantages of both high input impedance of MOSFET and low on-state voltage drop of GTR (Transistor), and has low driving power and reduced saturation voltage.
Specifically, the control circuit 200 includes: a control unit 210, a threshold adjusting unit 220, a first protection unit 240, and a driving unit 260. The control unit 210 is configured to generate a first control signal PWM1 according to a sampled voltage Vin _ sa of the input voltage, a sampled voltage Vout _ sa of the output voltage, a sampled voltage Iin _ sa of the input current, and a target voltage in the main circuit 120, and obtain a target current signal according to a load state of the load 130. The threshold adjusting unit 220 obtains a first reference voltage Vref used for representing a current limiting protection threshold according to the target current signal. The first protection unit 240 obtains the second control signal PWM2 according to the sampled voltage Iin _ sa of the input current, the first reference voltage Vref, and the first control signal PWM 1. The driving unit 260 provides a driving signal Vgate to the control terminal of the power switch T1 according to the second control signal PWM2 to drive the power switch T1 in the main circuit 120, so that the main circuit 120 obtains an output voltage Vout according to the input voltage Vin.
Specifically, the first protection unit 240 compares the sampled voltage Iin _ sa of the input current with the first reference voltage Vref, and determines the state of the second control signal PWM2 according to the comparison result. In each PWM control period, when the comparison result indicates that the sampled voltage Iin _ sa of the input current is greater than or equal to the first reference voltage Vref, the first protection unit 240 generates an invalid second control signal PWM2, and the driving unit 260 turns off the power switch T1 in the main circuit 120 according to the invalid second control signal PWM 2.
In this embodiment, the first control signal PWM1 is a square wave signal with a certain duty ratio, and the first control signal PWM1 is active at a high level and inactive at a low level; the second control signal PWM2 is active high and inactive low.
Further, the switching power supply further includes an input current sampling unit 251, an input voltage sampling unit 252, an output voltage sampling unit 253, and a load state detection unit 254. The input current sampling unit 251, the input voltage sampling unit 252, and the output voltage sampling unit 253 respectively detect the input current Iin, the input voltage Vin, and the output voltage Vout of the main circuit 120 to obtain a sampled voltage Iin _ sa of the input current, a sampled voltage Vin _ sa of the input voltage, and a sampled voltage Vout _ sa of the output voltage. The load state detection unit 254 is configured to detect a load state of the switching power supply (for example, obtain load state information by detecting a load current or a load power, etc.) to obtain a target voltage. As a non-limiting example, the load state detection unit 254 is, for example, a PI controller, whose inputs are a reference value characterizing the target load state and a detection value characterizing the actual load state, respectively, and whose output is a target voltage. The load state detection unit 254 obtains the target voltage signal according to feedback adjustment of the actual load state. The control unit 210 calculates the first control signal PWM1 and the target current signal according to the sampled voltage Iin _ sa, the sampled voltage Vin _ sa, the sampled voltage Vout _ sa, and the target voltage.
Further, the switching power supply further includes a second protection unit 270, configured to compare the sampled voltage Iin _ sa of the input current with an internal second reference voltage representing the first overcurrent protection threshold, and when the sampled voltage Iin _ sa of the input current is greater than or equal to the internal second reference voltage, the second protection unit 270 generates an active first trigger signal, the driving unit 260 turns off the power switch T1 in the main circuit 120 according to the active first trigger signal, and meanwhile, the control unit 210 outputs an inactive first control signal PWM1 according to the active first trigger signal. Illustratively, the second protection unit 270 is a hardware overcurrent protection unit, and a standard comparator is used to compare the sampled voltage Iin _ sa of the input current with a fixed internal second reference voltage.
Further, the control circuit 200 further includes a third protection unit 280, the third protection unit 280 compares the sampled voltage Iin _ sa of the input current with an internal third reference voltage representing a second overcurrent protection threshold, when the sampled voltage Iin _ sa of the input current is greater than or equal to the internal third reference voltage, the third protection unit 280 generates an active second trigger signal, and the control unit 210 outputs an inactive first control signal PWM1 according to the active second trigger signal. In an example, the third protection unit 280 is a software overcurrent protection unit, the AD converter is used to convert the sampled voltage Iin _ sa of the input current into a digital quantity, and a second trigger signal is generated through software filtering and comparison operation.
In this embodiment, the first overcurrent protection threshold is greater than the current-limiting protection threshold, the current-limiting protection threshold is greater than the second overcurrent protection threshold, the corresponding internal second reference voltage is greater than the first reference voltage, and the first reference voltage is greater than the internal third reference voltage.
Fig. 2 shows a schematic diagram of the structure of the control unit in fig. 1. As shown in fig. 2, the control unit 210 includes a duty signal generation unit 211 and a PWM generation unit 212. The duty signal generating unit 211 is configured to generate a duty signal according to the received sampling voltage Iin _ sa of the input current, the sampling voltage Vin _ sa of the input voltage, the sampling voltage Vout _ sa of the output voltage, and the target voltage. The PWM generating unit 212 is configured to generate the first control signal PWM1 according to the duty ratio signal and the first trigger signal and the second trigger signal. The PWM generating unit 212 outputs the first control signal PWM1 that is active when all of the first and second trigger signals are inactive, and outputs the first control signal PWM1 that is inactive when one of the first and second trigger signals is active. In addition, the PWM generation unit 212 also outputs a PWM reset signal to the first protection unit 240 at the beginning of each PWM control period.
In this embodiment, the first trigger signal and the second trigger signal are active at a high level and inactive at a low level.
Fig. 3 shows a schematic structural diagram of the duty ratio signal generating unit in fig. 2. As shown in fig. 3, the duty signal generation unit 211 includes, as a non-limiting example, an addition module 2111, a linear control module 2112, a multiplication module 2113, a phase calculation module 2114, an addition module 2115, and a linear control module 2116. The adding module 2111 is configured to calculate a first error according to a sampling voltage Vout _ sa of the output voltage and a target voltage, the linear control module 2112 obtains an effective value of the input current according to the first error, the phase calculation module 2114 obtains a phase value of the sampling voltage Vin _ sa of the input voltage according to the sampling voltage Vin _ sa of the input voltage, the multiplication module 2113 obtains a target current signal according to the effective value of the input current and the phase value of the sampling voltage Vin _ sa of the input voltage, the adding module 2115 calculates a second error between the sampling voltage Iin _ sa of the input current and the target current signal, and the linear control module 2116 generates a duty ratio signal according to the second error. The linear control module 2112 and the linear control module 2116 are, for example, PI controllers (Proportional Integral controllers), and the first error and the second error are close to 0 in a steady state by setting a Proportional coefficient, an Integral coefficient, a maximum-minimum limiter, and the like in the linear control module 2112 and the linear control module 2116. The operating principle of the PI controller is common knowledge of those skilled in the art, and is not described herein again.
Fig. 4 shows a schematic structural diagram of the threshold adjusting unit in fig. 1. As shown in fig. 4, the threshold adjusting unit 220 includes a software adjusting module 221 and a digital-to-analog converting module 222.
The software adjusting module 221 receives the target current signal, and obtains a current limiting protection threshold value through software calculation according to the target current signal. Specifically, the software adjusting module 221 adds a preset protection margin on the basis of the summation of the maximum value of the target current signal and the current ripple amplitude, and finally obtains the current-limiting protection threshold, thereby implementing flexible adjustment of the current-limiting protection threshold.
The digital-to-analog conversion module 222 receives the current-limiting protection threshold, and performs digital-to-analog conversion on the current-limiting protection threshold to generate a first reference voltage Vref.
Fig. 5 is a schematic structural diagram of the first protection unit in fig. 1. As shown in fig. 5, the first protection unit 240 includes a comparison module 241, a second indication signal generation unit 242, and a fault management module 243. The comparison module 241 compares the first reference voltage Vref with the sampled voltage Iin _ sa of the input current, and when the sampled voltage Iin _ sa of the input current is greater than or equal to the first reference voltage Vref, the comparison module 241 generates an effective first indication signal. The second indication signal generating unit 242 is configured to generate a valid second indication signal when a count value of the first indication signal is greater than or equal to a preset value within a first preset time. The fault management module 243 generates the active or inactive second control signal PWM2 based on the first indication signal, the second indication signal, and the first control signal PWM 1. The power switch tube current limiting protection circuit can ensure that when the input current is increased due to abnormal disturbance, the input current is not higher than the set current limiting protection threshold all the time, and can quickly recover the normal work of the power switch tube, thereby avoiding the situation that the output voltage is too low due to long-time turn-off of the power switch tube.
The fault management module 243 is responsible for output management of the second control signal PWM2, and if the fault management module 243 receives the valid first indication signal and the valid second indication signal, the invalid second control signal PWM2 is output, and at this time, the second control signal PWM2 is maintained in a low level state; if the fault management module 243 does not receive valid first and second indication signals, the output second control signal PWM2 is in agreement with the first control signal PWM1 state.
Fig. 6 illustrates a schematic configuration diagram of the second indication signal generation unit in fig. 5. As shown in fig. 6, the second indication signal generating unit 242 includes a counting module 2421, a first timer 2422, a latch module 2423, and a second timer 2424. The counting module 2421 is used for counting the valid first indication signals. When the count value of the first indication signal which is effective in the first preset time is greater than or equal to the preset value, the counting module 2421 generates an effective intermediate indication signal; otherwise, an invalid intermediate indication signal is generated. The latch module 2423 is used for latching the valid intermediate indication signal and generating a valid second indication signal according to the valid intermediate indication signal. The first timer 2422 is configured to repeatedly time and generate an active count reset signal when the first preset time is reached, and the counting module 2421 resets the count value of the first indication signal according to the active count reset signal and restarts counting. The second timer 2424 starts timing when receiving a valid intermediate indication signal and generates a valid fault clearing signal after a second preset time elapses, the latch module 2423 generates an invalid second indication signal according to the valid fault clearing signal, and the second timer 2424 stops working and starts working when receiving the next valid intermediate indication signal.
In this embodiment, the first indicator signal, the intermediate indicator signal, and the second indicator signal are active low and inactive high, and the count reset signal and the fault clear signal are active high and inactive low.
Fig. 7 shows a schematic diagram of the structure of the fault management module in fig. 5. In the present embodiment, the fault management module 243 has two modes, cycle-by-cycle protection and single-time protection. Specifically, as shown in fig. 7, the fault management module 243 includes a first latch 2431, a second latch 2432, and an and gate 2433. The first latch 2431 includes a first set terminal for receiving the first indication signal, a first reset terminal for receiving the PWM reset signal, and a first output terminal. The second latch 2432 includes a second set terminal for receiving the second indication signal, a second reset terminal for receiving the PWM reset signal, and a second output terminal. The and gate 2433 includes first to third input terminals for receiving the first control signal PWM1, a second input terminal connected to the first output terminal of the first latch 2431, a third input terminal connected to the second output terminal of the second latch 2432, and a third output terminal connected to the input terminal of the driving unit 260. The and gate 2433 is used to generate the second control signal PWM2 according to the output signals of the first and second latches 2431 and 2432 and the first control signal PWM 1.
For example, the first latch 2431 generates an active first fault signal when receiving an active first indication signal and sets the cycle-by-cycle protection mode flag bit, and the and gate 2433 generates an inactive second control signal PWM2 based on the active first fault signal. The first latch 2431 generates an inactive first fail signal upon receiving an active PWM reset signal and an inactive first indication signal, and simultaneously resets the cycle-by-cycle protection mode flag bit, and the gate 2433 generates the second control signal PWM2 in accordance with the state of the PWM1 (assuming that the second fail signal output from the second latch 2432 is in an inactive state at this time), and the second control signal PWM2 and the first control signal PWM1 at this time are identical. In the cycle-by-cycle protection, when the input current exceeds the current-limiting protection threshold, software intervention is not required in each PWM control cycle, the power switch transistor T1 in the main circuit 120 can be turned off or turned on only by the cycle-by-cycle protection inside the fault management module 243, so as to prevent the input current from flowing through the power switch transistor T1 and the subsequent devices from being damaged, and the power switch transistor T1 of the main circuit 120 can also be turned on quickly, so as to prevent the output voltage from being too low.
For another example, the second latch 2432 generates an active second fault signal when receiving an active second indication signal, sets the one-time protection mode flag bit, and the and gate 2433 generates an inactive second control signal PWM2 according to the active second fault signal, and the second control signal PWM2 is always at a low level. The second latch 2432 is further configured to generate an inactive second fault signal when receiving the active PWM reset signal and the inactive second indication signal, and the and gate 2433 generates the second control signal PWM2 according to the inactive second fault signal and the state of the first control signal PWM1 (assuming that the first fault signal output by the first latch 2431 is in an inactive state at this time). In the single protection mode, the flag bit of the single protection mode needs to be cleared by software to recover the output of the control signal, namely, compared with the cycle-by-cycle protection, once the single protection is effective, the flag bit of the single protection mode can be reset only when an effective fault clearing signal is detected, and the switching power supply recovers the normal working state.
Fig. 8 shows a schematic configuration diagram of a switching power supply according to a second embodiment of the present invention. As shown in fig. 8, a switching power supply of a second embodiment of the present invention is substantially the same as the switching power supply of the first embodiment described above, except that: the threshold adjusting unit 320 in the switching power supply of this embodiment is further configured to obtain a second overcurrent protection threshold of the third protection unit 380 according to the target current signal provided by the control unit 310.
Further, fig. 9 shows a schematic structural diagram of the threshold adjusting unit in fig. 8. As shown in fig. 9, the threshold adjusting unit 320 includes a software adjusting module 321 and a digital-to-analog converting module 322, where the software adjusting module 321 receives the target current signal and obtains a current-limiting protection threshold and a second overcurrent protection threshold through software calculation according to the target current signal. Specifically, the software adjusting module 321 adds a preset first protection margin to the sum of the maximum value of the target current signal and the current ripple amplitude to obtain a second overcurrent protection threshold, and then adds a second protection margin to the second overcurrent protection threshold to obtain a current-limiting protection threshold, thereby implementing flexible adjustment of the current-limiting protection threshold and the second overcurrent protection threshold.
The digital-to-analog conversion module 322 receives the current-limiting protection threshold, and performs digital-to-analog conversion on the current-limiting protection threshold to generate a first reference voltage Vref.
Besides, the structures and operating principles of the control unit 310, the threshold adjusting unit 320, the first protection unit 340, the driving unit 360, the second protection unit 370, the third protection unit 380, the input current sampling unit 351, the input voltage sampling unit 352, the output voltage sampling unit 353 and the load state detecting unit 354 in the switching power supply of the second embodiment are the same as those in the switching power supply of the first embodiment, and are not described herein again.
Fig. 10 is a timing diagram illustrating the operation of the switching power supply according to the embodiment of the present invention. In the timing diagram of fig. 10, the switching power supply operates in a plurality of successive PWM control periods, and each PWM control period is the period from one active PWM reset signal to the next active PWM reset signal. For example, the first PWM control cycle is a time period between times t0-t 2. In addition, in fig. 10, both the first control signal PWM1 and the second control signal PWM2 are active high and inactive low; the fault clearing signal and the PWM reset signal are active at a high level and inactive at a low level. The first indication signal and the second indication signal are both active at low level and inactive at high level.
As described above, the control circuit of the switching power supply of the embodiment of the present invention includes the cycle-by-cycle protection mode and the single-shot protection mode. In the cycle-by-cycle protection mode, when the sampled voltage Iin-sa of the input current exceeds the first reference voltage Vref, the power switch tube T1 in the main circuit 120 can be turned off or turned on only by the fault management module without software intervention in each PWM control cycle, so as to prevent the input current from damaging the power switch tube T1 and subsequent devices, and also to quickly turn on the power switch tube T1 in the main circuit 120, so as to prevent the output voltage from being too low. In the single protection mode, when the times that the input current exceeds the current-limiting protection threshold value in a plurality of PWM control periods reach a preset value, the single protection mode is started, and compared with the period-by-period protection mode, once the single protection mode takes effect, the flag bit of the single protection mode can be reset only when an effective fault clearing signal is detected, and the switching power supply recovers the normal working state.
At time t0, the PWM reset signal is in an active state, while the first and second indication signals are inactive, the second control signal generated by the fault management module is active, and the sampled voltage Iin-sa of the input current gradually increases.
At time T1, the sampling voltage Iin-sa of the input current is greater than or equal to the first reference voltage Vref, the output of the comparison module is inverted, the first indication signal is inverted to an active state, the fault management module generates an invalid second control signal, the power switch tube T1 in the main circuit 120 is turned off, and the sampling voltage Iin-sa of the input current is gradually reduced.
At time t2, the PWM reset signal is again inverted to an active state, and at this time, the first indication signal and the second indication signal are in an inactive state, so the second control signal generated by the fault management module is active, and the sampling voltage Iin-sa of the input current gradually increases. The working processes of the time t0-t1 and the time t1-t2 are repeated at the later time t2-t3, time t4-t5, time t3-t4 and time t5-t6 respectively, and are not described again.
At time T6, the PWM reset signal is inverted to the active state again, when the number of times that the first indication signal is active reaches a preset value, the second indication signal is inverted from the inactive state to the active state, the fault management module generates an inactive second control signal, the power switch T1 in the main circuit 120 is turned off, and the sampling voltage Iin-sa of the input current is gradually reduced.
At time T7, the PWM reset signal is again toggled to the active state, and the second indication signal is still active, so the fault management module generates an inactive second control signal and the power switch T1 in the main circuit 120 is still in the off state.
At time t8, the fault clear signal is inverted to the active state, and the latch module in the second indication signal generation unit inverts the second indication signal from the active state to the inactive state according to the active fault clear signal.
At time t9, the PWM reset signal is again inverted to an active state, and at this time, the first indication signal and the second indication signal are in an inactive state, so the second control signal generated by the fault management module is active, and the sampling voltage Iin-sa of the input current gradually increases.
At time T10, the sampling voltage Iin-sa of the input current is greater than or equal to the first reference voltage Vref, the output of the comparison module is inverted, the first indication signal is inverted to an active state, the fault management module generates an invalid second control signal, the power switch tube T1 in the main circuit 120 is turned off, and the sampling voltage Iin-sa of the input current is gradually reduced.
Fig. 11 shows a waveform diagram of overcurrent protection of a switching power supply according to the prior art and a second embodiment of the present invention. In fig. 11, the broken line indicates the overcurrent protection threshold and the waveform of the input current of the switching power supply of the related art, and the solid line indicates the current-limiting protection threshold and the waveform of the input current of the switching power supply of the second embodiment of the present invention. As shown in fig. 11, the prior art switching power supply can only set a highest fixed threshold, and if the input current is relatively small when overcurrent occurs, a large overshoot of the input current occurs. The current-limiting protection threshold value of the switching power supply of the embodiment of the invention is changed along with the change of the target current signal obtained according to the load state of the switching power supply, so that the input current of the switching power supply can be always controlled within a certain range when the switching power supply works under different load conditions, and the current is prevented from generating larger fluctuation.
Fig. 12 shows a method flowchart of a control method of a switching power supply according to a third embodiment of the present invention. The switching power supply of this embodiment may be the switching power supply of the above embodiment, and includes a rectifier bridge 110, a main circuit 120, an output capacitor Cout, a load 130, and a control circuit. The input terminal of the main circuit 120 is connected to the rectifier bridge 110, and the output terminal is connected to the load 130. The main circuit 120 includes an inductor Lf, a power switch tube T1, a fast recovery diode VD, and a sampling resistor Rsen. The control circuit is not only used for controlling the on and off of the power switch tube, but also used for detecting the input current of the main circuit in real time and performing input current overcurrent protection on the circuit, and if the detected input current is higher than a set current limiting protection threshold value, the power switch tube T1 in the main circuit 120 is turned off in time to prevent the failure of the power switch tube T1 and a rear-end device caused by overhigh input current. As shown in fig. 12, the control method includes the following steps S110 to S150.
In step S110, the input current is sampled to obtain a sampled voltage of the input current.
In step S120, a first control signal and a target current signal are generated.
In a further embodiment, the control method further comprises generating the first control signal and the target current signal from a sampled voltage of the input current, a target voltage, a sampled voltage of the input voltage, and a sampled voltage of the output voltage.
In step S130, a first reference voltage is obtained according to the target current signal. For example, the current-limiting protection threshold may be obtained according to a maximum value of the target current signal, an amplitude of a current ripple, and a preset protection margin, and digital-to-analog conversion may be performed on the current-limiting protection threshold to obtain the first reference voltage.
In a further embodiment, the control method further includes adjusting the first reference voltage according to a load state of the switching power supply, for example, a target voltage may be obtained according to load state information such as a load current or a load power of the main circuit 120, and then the target current signal and the first reference voltage under different load states are obtained.
In a further embodiment, the control method further comprises the step of adjusting a second overcurrent protection threshold of the software overcurrent protection in real time according to the load state, so that the safety and the stability of the switching power supply when the switching power supply encounters power grid fluctuation under different load conditions are further improved.
In step S140, a second control signal is obtained according to the sampled voltage of the input current, the first reference voltage, and the first control signal.
In step S150, a driving signal for controlling the power switch tube is output according to the second control signal.
Further, the control method further includes generating an invalid second control signal when the sampling voltage of the input current is greater than or equal to the first reference voltage in each PWM control period, and turning off the power switch tube according to the invalid second control signal, and outputting a second control signal according to a PWM reset signal to turn on the power switch tube when a next PWM control period adjacent to the PWM control period starts.
Further, the control method further comprises the step of turning off the power switch tube when the number of times that the sampling voltage of the input current is greater than or equal to the first reference voltage within a first preset time reaches a preset value and a fault clearing signal is not received.
Fig. 13 is a detailed flowchart illustrating a control method according to a third embodiment of the present invention. Specifically, the control method of the present embodiment further includes steps S210 to S260.
In step S210, it is determined whether the sampled voltage of the input current is equal to or greater than a first reference voltage. If the sampling voltage of the input current is greater than or equal to the first reference voltage, continuing to step S220; if the sampled voltage of the input current is smaller than the first reference voltage, the step S230 is continued.
In step S220, an effective first indication signal is output, the counting module counts the effective first indication signal, and the count value of the counting module is incremented by 1. In this embodiment, when the sampling voltage of the input current is greater than or equal to the first reference voltage, the comparison module generates an effective first indication signal. The fault management module generates an invalid second control signal based on the valid first indication signal. And the counting module counts the pulses of the first indicating signal to obtain a count value.
In step S230, it is determined whether a first preset time is reached. If the first preset time is reached, continuing to step S240; if the first preset time is not reached, the control flow is exited, and the process is restarted, and the determination logic of step S210 is continuously executed.
In step S240, it is determined whether the count value of the first indication signal is greater than or equal to a preset value. If the count value of the first indication signal is greater than or equal to the preset value, continuing to step S250; if the count value of the first indication signal is smaller than the preset value, the step S260 is continued.
In step S250, a valid second indication signal is generated. In this embodiment, the counting module counts the first indication signal within a first preset time, and when a count value of the first indication signal within the first preset time is greater than or equal to a preset value, the counting module generates a valid second indication signal. And the fault management module generates an invalid second control signal according to the valid second indication signal, and the switching power supply enters a single-time protection mode.
In step S260, the count value of the first instruction signal is cleared. In this embodiment, after each first preset time, the count value of the first indication signal is cleared and the count is restarted, and then the control flow exits and is restarted, and the determination logic of step S210 is continuously executed.
Fig. 14 and 15 show schematic flowcharts of the cycle-by-cycle protection mode and the single-shot protection mode of the control method according to the third embodiment of the present invention, respectively.
As shown in fig. 14, the cycle-by-cycle protection mode of the control method includes steps S310 to S380.
In step S310, a first control signal is received.
In step S320, it is determined whether a valid PWM reset signal is received. If a valid PWM reset signal is received, continue to step S330; if the valid PWM reset signal is not received, step S340 is continued.
In step S330, the first fault signal is cleared.
In step S340, it is determined whether a valid first indication signal is received. If the valid first indication signal is received, continuing to step S350; if the valid first indication signal is not received, the step S360 is continued.
In step S350, a valid first fault signal is generated. In this embodiment, the fault management module further comprises a first latch that generates a first fault signal upon receiving a valid first indication signal.
In step S360, it is determined whether a valid first fault signal is received. If a valid first fault signal is received, continue to step S370; if a valid first failure signal is not received, step S380 is continued.
In step S370, the inactive second control signal PWM2 is output. In this embodiment, the fault management module further comprises an and gate that generates an inactive second control signal PWM2 when receiving an active first fault signal.
In step S380, the output second control signal is consistent with the state of the first control signal.
In this embodiment, the first latch clears the first fault signal when receiving the valid PWM reset signal and simultaneously receiving the invalid first indication signal, and the state of the second control signal output by the and gate is consistent with the state of the first control signal.
In the cycle-by-cycle protection mode, when the input current exceeds the current-limiting protection threshold, software intervention is not needed in each PWM control cycle, the power switch tube in the main circuit can be turned off only through the cycle-by-cycle protection in the fault management module, the power switch tube and subsequent devices are prevented from being damaged by input current overshoot, the power switch tube in the main circuit can be rapidly turned on in the next PWM control cycle, and the output voltage is prevented from being too low.
As shown in fig. 15, the single protection mode of the control method includes steps S410 to S480.
In step S410, a first control signal is received.
In step S420, it is determined whether a valid PWM reset signal is received. If a valid PWM reset signal is received, continue to step S430; if the valid PWM reset signal is not received, the process continues to step S440.
In step S430, the second fault signal is cleared.
In step S440, it is determined whether a valid second indication signal is received. If a valid second indication signal is received, continuing to step S450; if a valid second indication signal is not received, the process continues to step S460.
In step S450, a valid second fault signal is generated. In this embodiment, the fault management module further comprises a second latch that generates a second fault signal when a valid second indication signal is received.
In step S460, it is determined whether a valid second failure signal is received. If a valid second failure signal is received, continue to step S470; if a valid second failure signal is not received, step S480 continues.
In step S470, the invalid second control signal is output. In this embodiment, the fault management module further comprises an and gate that generates an inactive second control signal PWM2 when receiving an active second fault signal.
In step S480, the output second control signal coincides with the state of the first control signal. In this embodiment, the second latch clears the second fault signal when receiving the valid PWM reset signal and simultaneously receiving the invalid second indication signal, and the state of the second control signal output by the and gate is consistent with the state of the first control signal.
In the single-shot protection mode, when the input current exceeds the current-limiting protection threshold value for a plurality of times within a certain time (including a plurality of PWM control periods), the switching power supply enters the single-shot protection mode, and the switching power supply is required to be restarted until a fault clearing signal is received. Even under the condition that the input current is frequently overcurrent, the input current can be ensured to be always close to the set current-limiting protection threshold value for carrying out small-amplitude fluctuation, overvoltage impact on devices such as a filter capacitor and a load at the rear end is avoided to the greatest extent, and the stability of the system and the service life of the devices are improved.
In summary, the switching power supply according to the embodiment of the invention can modify the overcurrent protection threshold and the current-limiting protection threshold in real time according to the load state, so as to ensure that the input current is always controlled within a certain range when the switching power supply works under different load conditions and meets the power grid fluctuation, prevent the input current from generating large fluctuation, and protect devices such as a rear-end filter capacitor and a load.
In a further embodiment, the switching power supply can adjust the second overcurrent protection threshold value of the software overcurrent protection in real time according to the load state, so that the safety and the stability of the switching power supply when the switching power supply encounters power grid fluctuation under different load conditions are further improved.
In a further embodiment, the switching power supply of the embodiment of the invention provides two-stage hardware overcurrent protection, when input current triggers overshoot due to certain external interference, the input current can be ensured to be always below a set current-limiting protection threshold, the overshoot amplitude of the input current is reduced, frequent overcurrent impact on a filter capacitor, a load and the like at the rear end is avoided to the greatest extent, and the stability of a system and the service life of devices are improved. And even though accidental false triggering occurs, the power switch tube of the main circuit can be quickly opened in the next PWM control period, so that the condition that the output voltage is too low and the normal work of a power supply system is not influenced is prevented, the frequent shutdown of the system due to overcurrent protection can be avoided under the condition that the power grid fluctuates frequently and violently, and the user experience of related products is improved.
In a further embodiment, when the input current exceeds the current limiting protection threshold value for a plurality of times within a certain time, the switching power supply enters a single protection mode, and a fault clearing signal is required to be received before the switching power supply can be restarted. Even under the condition of frequent overcurrent, the input current can be ensured to be always near the set overcurrent protection threshold value for carrying out small-amplitude fluctuation, overvoltage impact on devices such as a filter capacitor and a load at the rear end is avoided to the greatest extent, and the stability of the system and the service life of the devices are improved.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
While embodiments in accordance with the invention have been described above, these embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. The invention is limited only by the claims and their full scope and equivalents.

Claims (29)

1. A control circuit for a switching power supply, the control circuit comprising:
an input current sampling unit which samples an input current to obtain a sampling voltage of the input current;
a control unit generating a first control signal and a target current signal;
the threshold value adjusting unit is connected with the control unit and obtains a first reference voltage representing a current-limiting protection threshold value according to the target current signal;
the first protection unit is connected with the control unit and outputs a second control signal according to the sampling voltage of the input current, the first reference voltage and the first control signal; and
the driving unit is connected with the first protection unit, outputs a driving signal for controlling a power switch tube according to the second control signal, and turns off the power switch tube according to the second control signal when the sampling voltage of the input current is greater than or equal to the first reference voltage,
wherein the threshold value adjusting unit adjusts the current limiting protection threshold value in real time according to the load state of the switching power supply so that the input current is always kept below the current limiting protection threshold value,
wherein the first protection unit includes:
the counting module is used for counting a first indicating signal which indicates that the sampling voltage of the input current is greater than the first reference voltage to obtain a counting value, generating an intermediate indicating signal according to the counting value, and enabling the intermediate indicating signal to be effective when the counting value is greater than or equal to a preset value within first preset time;
the latch module is connected with the counting module and used for latching the intermediate indication signal and generating a second indication signal according to the intermediate indication signal;
the first timer is used for repeatedly timing, generating a counting reset signal after the first preset time, resetting the counting value according to the counting reset signal by the counting module and restarting counting; and
the second timer starts timing when the intermediate indication signal is valid, generates a fault clearing signal after a second preset time, and the latch module generates a second indication signal according to the fault clearing signal and the intermediate indication signal, wherein the second indication signal is used for indicating the driving unit to turn off the power switch tube.
2. The control circuit of claim 1, wherein the threshold adjustment unit comprises:
the software adjusting module receives the target current signal and obtains a current-limiting protection threshold according to the target current signal; and
and the digital-to-analog conversion module is used for receiving the current-limiting protection threshold value and carrying out digital-to-analog conversion on the current-limiting protection threshold value to generate the first reference voltage.
3. The control circuit of claim 2, wherein the software adjusting module obtains the current-limiting protection threshold according to a maximum value of the target current signal, a magnitude of a current ripple, and a preset first protection margin.
4. The control circuit of claim 1, further comprising:
an input voltage sampling unit which samples an input voltage of the switching power supply to obtain a sampling voltage of the input voltage;
an output voltage sampling unit sampling an output voltage of the switching power supply to obtain a sampling voltage of the output voltage,
wherein the control unit generates the first control signal and the target current signal according to a sampling voltage of the input current, a target voltage, a sampling voltage of the input voltage, and a sampling voltage of the output voltage.
5. The control circuit of claim 4, wherein the control unit comprises:
a duty signal generation unit that generates a duty signal from the sampling voltage of the input current, the sampling voltage of the input voltage, the sampling voltage of the output voltage, and the target voltage; and
a PWM generating unit generating the first control signal and a PWM reset signal according to the duty ratio signal,
wherein the duty signal generating unit includes:
the first adding module is used for obtaining a first error according to the sampling voltage of the output voltage and the target voltage;
the first linear control module is used for obtaining an input current effective value according to the first error;
the phase calculation module is used for obtaining an input voltage phase value according to the sampling voltage of the input voltage;
the multiplication module is used for obtaining a target current signal according to the input current effective value and the input voltage phase value;
the second addition module is used for obtaining a second error according to the sampling voltage of the input current and the target current signal; and
and the second linear control module generates the duty ratio signal according to the second error.
6. The control circuit of claim 5, wherein the first linear control module and the second linear control module each comprise a PI controller.
7. The control circuit of claim 1, wherein the first protection unit further comprises:
the comparison module compares the first reference voltage with the sampling voltage of the input current and generates a first indication signal according to a comparison result;
the fault management module is connected with the comparison module and generates the second control signal according to the first indication signal, the first control signal and the PWM reset signal;
when the sampling voltage of the input current is larger than or equal to the first reference voltage, judging that the input current is over-current, outputting the second control signal by the fault management module to turn off the power switch tube, and outputting the second control signal by the fault management module according to the PWM reset signal to turn on the power switch tube in the next control period.
8. The control circuit of claim 7, wherein the fault management module comprises:
a first latch generating a first fail signal according to the PWM reset signal and the first indication signal;
an AND gate that generates the second control signal based on the first control signal and the first fault signal,
wherein the first fault signal is active when the first indication signal is active, the first fault signal is inactive when the PWM reset signal is active and the first indication signal is inactive,
when the first fault signal is invalid, the state of the second control signal is consistent with the state of the first control signal, and when the first fault signal is valid, the second control signal is invalid.
9. The control circuit of claim 8, wherein the fault management module further comprises:
a second latch to generate a second fail signal according to the PWM reset signal and the second indication signal,
wherein the second fail signal is active when a second indication signal is active, and the second fail signal is inactive when the PWM reset signal is active and the second indication signal is inactive,
when both the first fault signal and the second fault signal are invalid, the state of the second control signal is consistent with the state of the first control signal, and when one of the first fault signal and the second fault signal is valid, the second control signal is invalid.
10. The control circuit according to claim 4, further comprising a load state detection unit that obtains the target voltage by detecting a load state of the switching power supply, the target voltage varying in accordance with a change in the load state.
11. The control circuit according to claim 1, further comprising a hardware protection unit receiving the sampled voltage of the input current, wherein the hardware protection unit generates a first trigger signal when the sampled voltage of the input current is greater than or equal to a second reference voltage, the driving unit turns off the power switch tube according to the first trigger signal, and the control unit controls the first control signal to be in an inactive state according to the first trigger signal,
the second reference voltage is used for representing a first overcurrent protection threshold value, and the second reference voltage is larger than the first reference voltage.
12. The control circuit of claim 1, further comprising a software protection unit receiving the sampled voltage of the input current, the software protection unit generating a second trigger signal when the sampled voltage of the input current is greater than or equal to a third reference voltage, the control unit controlling the first control signal to be in an inactive state according to the second trigger signal,
wherein the third reference voltage characterizes a second over-current protection threshold, and the first reference voltage is greater than the third reference voltage.
13. The control circuit of claim 12, wherein the threshold adjustment unit is further configured to obtain the second over-current protection threshold according to the target current signal.
14. The control circuit of claim 13, wherein the threshold adjustment unit comprises:
and the software adjusting module is used for receiving the target current signal and obtaining the second overcurrent protection threshold according to the maximum value of the target current signal, the amplitude of the current ripple and a preset second protection margin.
15. A switching power supply comprising a control circuit as claimed in any one of claims 1 to 14.
16. The switching power supply according to claim 15, further comprising:
a rectifier bridge rectifying an alternating input voltage to obtain an input voltage;
the inductor, the power switch tube and the sampling resistor are connected in series at two ends of the rectifier bridge;
the anode of the diode is connected with the power switch tube and the middle node of the inductor;
and the output capacitor is connected between the sampling resistor and the intermediate node of the power switch tube and the cathode of the diode and is used for stabilizing the output voltage.
17. A control method of a switching power supply, characterized by comprising:
sampling the input current to obtain a sampled voltage of the input current;
generating a first control signal and a target current signal;
obtaining a first reference voltage representing a current-limiting protection threshold value according to the target current signal;
outputting a second control signal according to the sampling voltage of the input current, the first reference voltage and the first control signal; and
outputting a driving signal for controlling a power switch tube according to the second control signal, and turning off the power switch tube according to the second control signal when the sampling voltage of the input current is greater than or equal to the first reference voltage,
wherein the control method further comprises adjusting the current limiting protection threshold in real time according to the load state of the switching power supply so that the input current always remains below the current limiting protection threshold,
wherein the step of generating a second control signal according to the sampled voltage of the input current, a first reference voltage and the first control signal comprises:
counting a first indication signal representing that the sampling voltage of the input current is greater than the first reference voltage to obtain a count value, generating an intermediate indication signal according to the count value, and enabling the intermediate indication signal to be effective when the count value is greater than or equal to a preset value within first preset time;
latching the intermediate indication signal and generating a second indication signal according to the intermediate indication signal;
generating a counting reset signal after the first preset time, resetting the counting value according to the counting reset signal, and restarting counting; and
and starting timing when the intermediate indication signal is effective, generating a fault clearing signal after a second preset time, and generating a second indication signal according to the fault clearing signal and the intermediate indication signal, wherein the second indication signal is used for indicating to turn off the power switch tube.
18. The control method of claim 17, wherein the step of deriving the first reference voltage from the target current signal comprises:
receiving the target current signal, and obtaining a current-limiting protection threshold value according to the target current signal; and
and performing digital-to-analog conversion on the current-limiting protection threshold value to generate the first reference voltage.
19. The control method of claim 18, wherein the step of deriving a current limit protection threshold from the target current signal comprises:
and obtaining the current-limiting protection threshold according to the maximum value of the target current signal, the amplitude of the current ripple and a preset first protection margin.
20. The control method according to claim 17, characterized by further comprising:
sampling an input voltage of the switching power supply to obtain a sampled voltage of the input voltage;
sampling an output voltage of the switching power supply to obtain a sampled voltage of the output voltage; and
and generating the first control signal and the target current signal according to the sampling voltage of the input current, the target voltage, the sampling voltage of the input voltage and the sampling voltage of the output voltage.
21. The control method of claim 20, wherein the step of generating the first control signal and the target current signal based on the sampled voltage of the input current, the target voltage, the sampled voltage of the input voltage, and the sampled voltage of the output voltage comprises:
generating a duty cycle signal according to the sampling voltage of the input current, the sampling voltage of the input voltage, the sampling voltage of the output voltage and the target voltage; and
generating the first control signal and a PWM reset signal according to the duty ratio signal,
wherein the step of generating a duty cycle signal from the sampled voltage of the input current, the sampled voltage of the input voltage, the sampled voltage of the output voltage, and the target voltage comprises:
obtaining a first error according to the sampling voltage of the output voltage and the target voltage;
obtaining an input current effective value according to the first error;
obtaining an input voltage phase value according to the sampling voltage of the input voltage;
obtaining a target current signal according to the input current effective value and the input voltage phase value;
obtaining a second error according to the sampling voltage of the input current and the target current signal; and
generating the duty cycle signal according to the second error.
22. The control method of claim 17, wherein outputting a second control signal based on the sampled voltage of the input current, the first reference voltage, and the first control signal comprises:
comparing the first reference voltage with the sampling voltage of the input current, and generating a first indication signal according to the comparison result;
generating the second control signal according to the first indication signal, the first control signal and a PWM reset signal;
when the sampling voltage of the input current is greater than or equal to the first reference voltage, judging that the input current is over-current, outputting the second control signal to turn off the power switch tube,
and in the next control period, outputting the second control signal according to the PWM reset signal to conduct the power switch tube.
23. The control method of claim 22, wherein the step of generating the second control signal according to the first indication signal, the first control signal, and a PWM reset signal comprises:
generating a first fault signal according to the PWM reset signal and the first indication signal;
generating the second control signal based on the first control signal and the first fault signal,
wherein the first fault signal is active when the first indication signal is active, the first fault signal is inactive when the PWM reset signal is active and the first indication signal is inactive,
when the first fault signal is invalid, the state of the second control signal is consistent with the state of the first control signal, and when the first fault signal is valid, the second control signal is invalid.
24. The method of claim 23, wherein the step of generating a second control signal based on the sampled voltage of the input current, a first reference voltage, and the first control signal further comprises:
generating a second fault signal based on the PWM reset signal and the second indication signal,
wherein the second fail signal is active when a second indication signal is active, and the second fail signal is inactive when the PWM reset signal is active and the second indication signal is inactive,
when both the first fault signal and the second fault signal are invalid, the state of the second control signal is consistent with the state of the first control signal, and when one of the first fault signal and the second fault signal is valid, the second control signal is invalid.
25. The control method according to claim 20, characterized by further comprising: the target voltage is obtained by detecting a load state of the switching power supply, and the target voltage changes according to a change of the load state.
26. The control method according to claim 17, characterized by further comprising: when the sampling voltage of the input current is greater than or equal to a second reference voltage, generating a first trigger signal, switching off the power switch tube according to the first trigger signal, and controlling the first control signal to be in an invalid state,
the second reference voltage is used for representing a first overcurrent protection threshold value, and the second reference voltage is larger than the first reference voltage.
27. The control method according to claim 17, characterized by further comprising: generating a second trigger signal when the sampling voltage of the input current is greater than or equal to a third reference voltage, and controlling the first control signal to be in an invalid state according to the second trigger signal,
wherein the third reference voltage characterizes a second over-current protection threshold, and the first reference voltage is greater than the third reference voltage.
28. The control method of claim 27, further comprising deriving the second over-current protection threshold from the target current signal.
29. The control method of claim 28, wherein the step of deriving the second over-current protection threshold from the target current signal comprises:
and obtaining the second overcurrent protection threshold according to the maximum value of the target current signal, the amplitude of the current ripple and a preset second protection margin.
CN201911395751.7A 2019-12-30 2019-12-30 Switching power supply and control circuit and control method thereof Active CN111181370B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201911395751.7A CN111181370B (en) 2019-12-30 2019-12-30 Switching power supply and control circuit and control method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201911395751.7A CN111181370B (en) 2019-12-30 2019-12-30 Switching power supply and control circuit and control method thereof

Publications (2)

Publication Number Publication Date
CN111181370A CN111181370A (en) 2020-05-19
CN111181370B true CN111181370B (en) 2021-12-03

Family

ID=70652234

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201911395751.7A Active CN111181370B (en) 2019-12-30 2019-12-30 Switching power supply and control circuit and control method thereof

Country Status (1)

Country Link
CN (1) CN111181370B (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021248333A1 (en) * 2020-06-09 2021-12-16 华为数字能源技术有限公司 Buck circuit, buck apparatus and circuit control method
CN111799644B (en) * 2020-06-09 2022-12-09 深圳蚂里奥技术有限公司 Laser source protection circuit and laser source protection method
CN115333352B (en) * 2022-10-11 2023-02-07 七四九(南京)电子研究院有限公司 Output overcurrent protection method of power supply
CN116960900B (en) * 2023-09-19 2024-01-05 成都电科星拓科技有限公司 Integrated fault protection method for switching power supply IC

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100420113C (en) * 2005-06-17 2008-09-17 华为技术有限公司 Overcurrent protection circuit
US7692912B2 (en) * 2008-04-03 2010-04-06 Dell Products L.P. System and method for information handling system display backlight protection and monitoring
US8957658B2 (en) * 2013-01-31 2015-02-17 Sanken Electric Co., Ltd. Switching power-supply device
CN103280960B (en) * 2013-05-31 2015-04-15 华为技术有限公司 Current-limiting device and current-limiting method
CN105471250B (en) * 2014-08-19 2019-09-06 中兴通讯股份有限公司 Improve the method and device of digital pfc circuit reliability
CN104953814B (en) * 2015-06-29 2018-06-15 海信（山东）空调有限公司 A kind of method and apparatus for controlling pfc circuit
CN208190235U (en) * 2018-06-04 2018-12-04 珠海格力电器股份有限公司 A kind of overcurrent protective device, pfc circuit and air-conditioning
CN108923377B (en) * 2018-08-28 2020-01-24 海信（山东）空调有限公司 IGBT (insulated Gate Bipolar transistor) overcurrent protection device and method of PFC (Power factor correction) circuit
CN209016688U (en) * 2018-11-19 2019-06-21 南宁职业技术学院 A kind of intelligence overcurrent protective device
CN110311351B (en) * 2019-07-17 2022-05-03 易视智瞳科技（深圳）有限公司 Overcurrent protection circuit and load circuit

Also Published As

Publication number Publication date
CN111181370A (en) 2020-05-19

Similar Documents

Publication Publication Date Title
CN111082676B (en) Switching power supply and control circuit and control method thereof
CN111181370B (en) Switching power supply and control circuit and control method thereof
CN111130330B (en) Switching power supply and control circuit and control method thereof
US9825453B2 (en) Protection mode control circuit, switch control circuit including the protection mode control circuit and power supply device including the switch control circuit
CN103490605B (en) Isolated switch converter and controller and control method thereof
US8363369B2 (en) Short circuit and open circuit protection for a boost converter
US9906120B2 (en) Overcurrent protection system and method for inverter circuit
TWI506929B (en) Resonant converting circuit and resonant controller
US20140119063A1 (en) Power converting device and synchronous rectifier control circuit
KR20110103252A (en) Power factor correction circuit and driving method thereof
US9876423B2 (en) DC-to-DC converter
CN211557145U (en) Zero-cross detection circuit and switching power supply circuit
CN110752586B (en) Switching power supply and driving current and driving method thereof
KR20100000667A (en) Switch control device and converter comprising the same
CN111082677B (en) Switching power supply and control circuit and control method thereof
US9729043B2 (en) Power conversion apparatus and protection method thereof while feedback current signal being abnormal
CN110707925A (en) Zero-crossing detection circuit, zero-crossing detection method and switching power supply circuit
US20170338814A1 (en) Switch control circuit and switch circuit
CN210807067U (en) Load ignition protection circuit of solid-state modulator
CN109039113B (en) Switching power supply and control chip thereof
CN103904621A (en) Current-limiting protection and short-circuit protection circuit with self-recovery function
CN209860581U (en) Overcurrent protection circuit of PFC converter
TWI514731B (en) Over-voltage protection circuit and method for over-voltage protection
CN101958533B (en) Current sensing resistor short circuit protection device and method for isolated power supply
WO2015079580A1 (en) Power-supply device

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant