CN117040295A - Circuit capable of adjusting characteristic current based on MOSFET switching voltage and working method - Google Patents
Circuit capable of adjusting characteristic current based on MOSFET switching voltage and working method Download PDFInfo
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- CN117040295A CN117040295A CN202311040826.6A CN202311040826A CN117040295A CN 117040295 A CN117040295 A CN 117040295A CN 202311040826 A CN202311040826 A CN 202311040826A CN 117040295 A CN117040295 A CN 117040295A
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- 238000001514 detection method Methods 0.000 claims description 25
- 230000003287 optical effect Effects 0.000 claims description 12
- 239000003990 capacitor Substances 0.000 claims description 11
- 230000008878 coupling Effects 0.000 claims description 9
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- 238000005859 coupling reaction Methods 0.000 claims description 9
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- 239000013078 crystal Substances 0.000 claims description 4
- 238000002347 injection Methods 0.000 abstract description 5
- 239000007924 injection Substances 0.000 abstract description 5
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- 230000006641 stabilisation Effects 0.000 description 2
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- 230000002159 abnormal effect Effects 0.000 description 1
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- 230000009286 beneficial effect Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
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Classifications
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- 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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
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- 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
- H02H7/125—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 rectifiers
- H02H7/1252—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 rectifiers responsive to overvoltage in input or output, e.g. by load dump
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- 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
- H02H7/125—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 rectifiers
- H02H7/1257—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 rectifiers responsive to short circuit or wrong polarity in output circuit
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention provides a circuit and a working method of an adjustable characteristic current based on MOSFET switching voltage, wherein the circuit comprises the following components: MCU system, input protection module, rectifier module, steady voltage module, characteristic current sampling module, and MOSFET control module. The input protection module is sequentially connected with the rectifying module, the voltage stabilizing module and the MOSFET control module; the MOSFET control module is connected with the MCU system; the characteristic current sampling module is connected with the MOSFET Q2; the circuit is utilized, a characteristic current is generated by adopting a method of combining a constant current method and a constant resistance method, a MOSFET (metal oxide semiconductor field effect transistor) is adopted as a switching element, the switching frequency of the MODFET is controlled by an MCU (micro control unit) through an externally added auxiliary circuit, and the on-off of the MOSFET is realized according to the voltage applied to the two ends of a grid source of the MOSFET, so that the existence of the voltage on a sampling resistor is realized, and the loading injection of the characteristic current is controlled.
Description
Technical Field
The invention relates to the technical field of low-voltage power distribution and utilization, in particular to a circuit and a working method of an adjustable characteristic current based on MOSFET switching voltage.
Background
The problem that the connection relation of the user transformer is unclear exists in the low-voltage distribution transformer area, particularly in the newly-built transformer area, so that part of topology cannot be directly obtained at all, manual investigation workload is huge, and manpower and material resources are wasted. In order to solve the problems, an automatic acquisition of a topological structure relationship is provided by adopting a current injection method, by the method, characteristic currents are injected into a user side and each branch loop, each branch loop has a characteristic current detection function, and the grade relationship of the user ammeter and each branch is judged according to whether the branch loop flows through the characteristic currents by sequentially controlling the user ammeter side and the branch loop to inject the characteristic currents.
The characteristic current generation methods are roughly classified into two types: the first is a constant resistance method, which generates a characteristic current signal, and the load is put into the process with the resistance unchanged. According to the method, a thyristor or a relay is used as a switch, a resistor is used as a load, the thyristor and the resistor are connected in series, two ends of the resistor are respectively connected with an n line and a phase line, and voltage (v) is applied to two ends of the resistor (r) through turn-off of the thyristor to generate current (i), i=v/r. The scheme has simple principle, but has high requirements on devices, particularly the power of a sampling device is high, and the corresponding price and cost are high; the second type is a constant current method for generating a characteristic current signal, and the current is kept unchanged in the process to be input into a load.
Disclosure of Invention
The invention provides a circuit and a working method for adjusting characteristic current based on MOSFET switching voltage, which adopts a method of combining a constant current method and a constant resistance method to generate the characteristic current, adopts an MOSFET as a switching element, controls the switching frequency of the MODFET by an MCU through an externally added auxiliary circuit, and realizes the on-off of the MOSFET according to the voltage applied to the two ends of a gate source of the MOSFET, thereby realizing the voltage on a sampling resistor and controlling the loading injection of the characteristic current.
The invention provides a circuit for adjusting characteristic current based on MOSFET switching voltage, which comprises: MCU system: outputting a TL_PWM_SET control signal to a MOSFET control module;
an input protection module: the method is used for line protection;
and a rectification module: for providing a loop voltage for the control circuit;
and the voltage stabilizing module is used for: changing the grid voltage of the MOSFET into a set direct-current voltage;
and the characteristic current sampling module is used for: for obtaining a characteristic current;
MOSFET control module: receiving a control signal of the MCU system and controlling the on-off of the MOSFET; meanwhile, the voltage stabilizing module is connected to acquire voltage;
the input protection module is sequentially connected with the rectifying module, the voltage stabilizing module and the MOSFET control module; the MOSFET control module is connected with the MCU system; the characteristic current sampling module is connected with the MOSFET Q2. Further, an adjustable characteristic current signal circuit based on a MOSFET switching voltage, the MCU system comprising: chip, crystal oscillator and electric capacity.
Further, an adjustable characteristic current signal circuit based on MOSFET switching voltage is characterized in that the input protection module comprises a parallel resistor formed by R88 and R89 and a parallel resistor formed by R93 and R94; the input ends of R88 and R89 are connected with A phase voltage, and the output ends are connected with a voltage stabilizing module; the input ends of R93 and R94 are connected with rated voltage, and the output ends are connected with a voltage stabilizing module.
Further, an adjustable characteristic current signal circuit based on the switching voltage of a MOSFET is characterized in that the characteristic current sampling module comprises parallel resistors R102 and R103; one ends of R103 and R102 are grounded, the other ends are connected with the grid electrode of the MOSFET Q2 through a capacitor, and the other ends are also directly connected with the source electrode of the MOSFET Q2.
Further, an adjustable characteristic current signal circuit based on the switching voltage of a MOSFET is characterized in that the MOSFET control module comprises an optical coupling OP1, a blocking protection capacitor C96 and a voltage stabilizing tube D18; the positive electrode of the optical coupling OP1 input end is connected with the positive electrode of a 3.3V power supply; the negative electrode of the input end of the optical coupling OP1 is connected with the C electrode of the triode Q3 through a resistor; the E electrode of the triode Q3 is grounded; the TL_PWM_SET output end of the MCU system is connected with the B pole of the triode Q3 through a resistor and the blocking protection capacitor C96; the output end of the voltage stabilizing tube D18 is connected with the grid electrode of the MOSFET Q2.
Further, an adjustable characteristic current signal circuit based on the switching voltage of the MOSFET is characterized in that the rectifying module is full-wave rectification and comprises diodes VD1, VD2, VD3 and VD4.
Further, the adjustable characteristic current signal circuit based on the switching voltage of the MOSFET is characterized by further comprising a detection module, wherein the detection module comprises a PWM signal detection module and a MOSFET switching frequency detection module; the PWM signal detection module is used for detecting the frequency and the duty ratio of PWM.
Further, an adjustable characteristic current signal circuit based on the switching voltage of the MOSFET is characterized in that delta T is calculated when in delay according to a PWM signal detection module and a MOSFET switching frequency detection module; determining whether the signal output is correct or not according to the frequency and the duty ratio, and reminding the MCU system to adjust if the signal output is incorrect; in one PWM period, the required duty ratio is D (D is more than or equal to 0 and less than or equal to 1), the PWM period is T, the switching frequency of the MOSFET is f, the delay time delta T= |1/f-T| is adjusted within delta T before the start of the next period if the change of the frequency and the duty ratio of the PWM is detected, and an alarm prompt is sent to prompt the background to detect components if the switching frequency or the PWM frequency is still unstable within T+2delta T time after the adjustment or the change occurs after the stabilizing time is less than 3T+2delta T.
The invention discloses a working method of an adjustable characteristic current based on a MOSFET switching voltage, which is characterized by comprising the following steps:
s1, the MCU outputs a TL_PWM_SET control signal according to a SET switching frequency, and when the TL_PWM_SET signal is at a high level, the optical coupler OP1 is controlled to be conducted;
s2, the output of the voltage stabilizing circuit is connected with the input of the MOSFET control circuit, and the voltage stabilizing circuit is used for converting the grid voltage of the MOSFET into direct current voltage;
s3, when the grid voltage of the MOSFET Q2 is larger than the conducting voltage, the MOSFET Q2 is conducted,
s4, generating characteristic current by utilizing the voltage of the grid source two-electrode node of the Q2 and the parallel resistors R102 and R103; the characteristic current is superposed on the phase A loop;
s5, when the voltage of the node of the gate electrode and the source electrode of the MOSFET Q2 is smaller than the conducting voltage; MOSFET transistor Q2 is off.
The invention has the beneficial effects that: the embodiment mainly aims to control the on-off of the MOSFET and realize the accurate control of the load. The specific implementation process is as follows: the MCU system controls the MOSFET control module by outputting the TL_PWM_SET signal, and the module controls the on-off state of the MOSFET according to the received signal. The protection module is used for protecting the circuit and preventing the circuit from over-current, overvoltage and other problems. The rectification module is used for providing loop voltage for the control circuit and ensuring the stability of the circuit in the working process. The voltage stabilizing module changes the grid voltage of the MOSFET into a set direct-current voltage so as to ensure that the MOSFET can work normally. The characteristic current sampling module is used for obtaining characteristic current, so that current waveforms under the working state of the load can be obtained. Through the steps, the PWM controller can accurately control the load working state, and can feed back the actual load working condition through characteristic current sampling. The PWM control mode has the advantages of high response speed, high efficiency, stability, reliability and the like; the characteristic current is generated by adopting a method of combining a constant current method and a constant resistance method, a MOSFET (metal oxide semiconductor field effect transistor) is adopted as a switching element, the switching frequency of the MODFET is controlled by an MCU (micro control unit) through an externally added auxiliary circuit, and the on-off of the MOSFET is realized according to the voltage applied to the two ends of a grid source of the MOSFET, so that the existence of the voltage on a sampling resistor is realized, and the loading injection of the characteristic current is controlled.
Drawings
FIG. 1 is a system block diagram of a circuit for adjusting a characteristic current based on a switching voltage of a MOSFET;
FIG. 2 is a schematic diagram of the input protection module, voltage stabilizing module and rectifying module according to the present invention;
FIG. 3 is a schematic circuit diagram of the MCU system according to the present invention;
FIG. 4 is a schematic circuit diagram of a MOSFET control module and a characteristic current sampling module according to the present invention;
FIG. 5 is a schematic diagram of a detection module system according to the present invention.
Detailed Description
The preferred embodiments of the present invention will be described below with reference to the accompanying drawings, it being understood that the preferred embodiments described herein are for illustration and explanation of the present invention only, and are not intended to limit the present invention.
The embodiment is a circuit of adjustable characteristic current based on MOSFET switching voltage, which is characterized in that the circuit comprises:
MCU system: outputting a TL_PWM_SET control signal to a MOSFET control module;
an input protection module: the method is used for line protection;
and a rectification module: for providing a loop voltage for the control circuit;
and the voltage stabilizing module is used for: changing the grid voltage of the MOSFET into a set direct-current voltage;
and the characteristic current sampling module is used for: for obtaining a characteristic current;
MOSFET control module: receiving a control signal of the MCU system and controlling the on-off of the MOSFET; meanwhile, the voltage stabilizing module is connected to acquire voltage;
the input protection module is sequentially connected with the rectifying module, the voltage stabilizing module and the MOSFET control module; the MOSFET control module is connected with the MCU system; the characteristic current sampling module is connected with the MOSFET Q2.
Further, an adjustable characteristic current signal circuit based on MOSFET switching voltage, characterized in that the MCU system comprises: chip, crystal oscillator and electric capacity.
Further, an adjustable characteristic current signal circuit based on MOSFET switching voltage is characterized in that the input protection module comprises a parallel resistor formed by R88 and R89 and a parallel resistor formed by R93 and R94; the input ends of R88 and R89 are connected with A phase voltage, and the output ends are connected with a voltage stabilizing module; the input ends of R93 and R94 are connected with rated voltage, and the output ends are connected with a voltage stabilizing module.
Further, an adjustable characteristic current signal circuit based on the switching voltage of a MOSFET is characterized in that the characteristic current sampling module comprises parallel resistors R102 and R103; one ends of R103 and R102 are grounded, the other ends are connected with the grid electrode of the MOSFET Q2 through a capacitor, and the other ends are also directly connected with the source electrode of the MOSFET Q2. Further, an adjustable characteristic current signal circuit based on the switching voltage of a MOSFET is characterized in that the MOSFET control module comprises an optical coupling OP1, a blocking protection capacitor C96 and a voltage stabilizing tube D18; the positive electrode of the optical coupling OP1 input end is connected with the positive electrode of a 3.3V power supply; the negative electrode of the input end of the optical coupling OP1 is connected with the C electrode of the triode Q3 through a resistor; the E electrode of the triode Q3 is grounded; the TL_PWM_SET output end of the MCU system is connected with the B pole of the triode Q3 through a resistor and the blocking protection capacitor C96; the output end of the voltage stabilizing tube D18 is connected with the grid electrode of the MOSFET Q2.
Further, the adjustable characteristic current signal circuit according to claim 1, wherein the rectifying module is a full-wave rectifier, and includes diodes VD1, VD2, VD3, and VD4.
The working principle and the effect of the technical scheme are as follows: through MCU system: outputting a TL_PWM_SET control signal to a MOSFET control module; an input protection module: the method is used for line protection; and a rectification module: for providing a loop voltage for the control circuit; and the voltage stabilizing module is used for: changing the grid voltage of the MOSFET into a set direct-current voltage; and the characteristic current sampling module is used for: for obtaining a characteristic current; MOSFET control module: receiving a control signal of the MCU system and controlling the on-off of the MOSFET; and meanwhile, the voltage stabilizing module is connected to acquire voltage. The embodiment mainly aims to control the on-off of the MOSFET and realize the accurate control of the load. The chip U5, the crystal oscillator Y1, the capacitors C2, C3 and C4 form an MCU system part and are responsible for providing control signals for the characteristic current circuit, the switching frequency of the MOSFET is generated by PWM signals of the MCU, the frequency can be set, and meanwhile, the pulse width of the high level and the pulse width of the low level can be set. The characteristic current is mainly designed to be attached to a phase A loop of the voltage, R88, R89, R93 and R94 are loop current limiting resistors, so that a line protection effect is achieved, and when the loop current is too large, the current limiting resistors burn off to protect a later-stage circuit device. The diode groups VD1 to VD4 form a full wave rectifying circuit, loop voltage is provided for a later-stage control circuit, D16 is a voltage stabilizing diode, voltage stabilizing output DC22V is provided, and driving voltage is provided for a later-stage MOSFET. The TL_PWM_SET signal is a PWM control pulse output signal of a main MCU, C96 is a blocking protection capacitor, D18 is BTZ52-C15, the device is a voltage stabilizing tube, the voltage stabilizing output DC15V is a post-stage current sampling voltage, and the current sampling resistors R102 and R103 are connected in parallel with 56 ohms. When the TL_PWM_SET signal is at a high level, the MCU outputs a PWM control signal, the optocoupler OP1 is controlled to be conducted, a DC22V of the front-stage voltage stabilization output is connected to a rear-stage control circuit, the grid voltage of the Q2 is changed into a DC15V due to the voltage stabilization effect of D18, the conduction starting voltage of the MOSFET is DC3V, after the grid voltage is loaded with the DC15V, the MOSFET Q2 is conducted, and the voltage of the sampling resistors R102 and R103 is DC12V due to the node voltage of the grid source electrode of the Q2, so that 428ma characteristic current is generated, and when the MOSFET Q2 is conducted, the characteristic current is superposed on the A-phase loop. After the MOSFET is conducted, a drain voltage signal is connected to the source, and the drain voltage is a pulsating voltage, so that the voltage signal of the grid electrode is gradually increased, and when the node voltage of two stages of the grid source is smaller than the starting voltage of the MOSFET of DC3V, the MOSFET is turned off, so that loop injection of characteristic current is achieved, meanwhile, the power consumption acting on the MOSFET is reduced, and the requirement of circuit design is met. The MCU system controls the MOSFET control module by outputting the TL_PWM_SET signal, and the module controls the on-off state of the MOSFET according to the received signal. The protection module is used for protecting the circuit and preventing the circuit from over-current, overvoltage and other problems. The rectification module is used for providing loop voltage for the control circuit and ensuring the stability of the circuit in the working process. The voltage stabilizing module changes the grid voltage of the MOSFET into a set direct-current voltage so as to ensure that the MOSFET can work normally. The characteristic current sampling module is used for obtaining characteristic current, so that current waveforms under the working state of the load can be obtained. Through the steps, the PWM controller can accurately control the load working state, and can feed back the actual load working condition through characteristic current sampling. The PWM control mode has the advantages of high response speed, high efficiency, stability, reliability and the like.
The embodiment provides an adjustable characteristic current signal circuit based on MOSFET switching voltage, the circuit also comprises a detection module, wherein the detection module comprises a PWM signal detection module and an MOSFET switching frequency detection module; the PWM signal detection module is used for detecting the frequency and the duty ratio of PWM. Calculating delta T when in delay according to the PWM signal detection module and the MOSFET switching frequency detection module; determining whether the signal output is correct or not according to the frequency and the duty ratio, and reminding the MCU system to adjust if the signal output is incorrect; a description of the specification; in one PWM period, the required duty ratio is D (D is more than or equal to 0 and less than or equal to 1), the PWM period is T, the switching frequency of the MOSFET is f, the delay time delta T= |1/f-T| is adjusted within delta T before the start of the next period if the change of the frequency and the duty ratio of the PWM is detected, and an alarm prompt is sent to prompt the background to detect components if the switching frequency or the PWM frequency is still unstable within T+2delta T time after the adjustment or the change occurs after the stabilizing time is less than 3T+2delta T.
The working principle and the effect of the technical scheme are as follows: the detection module can effectively detect the frequency and the duty cycle of the PWM signal and use the calculated delay time Δt to determine whether the signal output is correct. If the frequency and the duty ratio of the PWM signal are detected to change, the system can adjust the time delta T in advance, so that the stable and reliable PWM signal output is ensured. By the detection module, abnormal operation or damage of the circuit caused by unstable PWM signals can be avoided. In addition, if the switching frequency or the PWM frequency is still unstable after adjustment or changes after a plurality of periods, an alarm prompt can be sent out so as to check whether the components have problems in time. Therefore, in practical application, the detection module can improve the stability and reliability of the PWM controller and ensure the normal operation of the circuit; calculating delay time through the switching frequency and the period of the PWM, reserving delay time delta T calculated by using the duty ratio and the frequency of the PWM before the next period starts, adjusting the delta T time before one period starts, reserving delay time, and ensuring that normal waveforms are input from a new period after adjustment; if the delay time delta T is added for adapting after the adjustment of the period T, and the waveform is still unstable in the delay time delta T of the next period, enough reaction and adjustment time are given to the system, if the waveform is unstable in the reaction and adjustment time, the system gives an alarm prompt if the component is problematic, and if the waveform is stable in the time T+2delta T, the waveform is just stable for less than 3 periods and is changed; the circuit system is also problematic, the reserved reaction time of the front and rear systems is added with 3 stable periods 3T+2DeltaT, the system is stably transited and observed, the time cannot be too long, the timeliness of the system reaction is influenced, a minimum period is set, the reaction time and the adjustment time of the front and rear delta T are respectively added, the reaction time and the adjustment time of the delta T are respectively added before and after the maximum period of 3, the accuracy and timeliness of the reaction are improved, and if the normal requirements still cannot be met in the time, the system gives an alarm so as to find and solve the problem in time; the delay time calculated according to the duty ratio and the PWM frequency is added with 1 to 3 waveform periods, so that the accuracy and timeliness of reaction are improved, and the problem of inaccurate sampling caused by the fact that the reaction is too short or feedback is not timely made for too long is prevented.
The embodiment provides a working method of an adjustable characteristic current based on a MOSFET switching voltage, which comprises the following steps:
s1, the MCU outputs a TL_PWM_SET control signal according to a SET switching frequency, and when the TL_PWM_SET signal is at a high level, the optical coupler OP1 is controlled to be conducted;
s2, the output of the voltage stabilizing circuit is connected with the input of the MOSFET control circuit, and the voltage stabilizing circuit is used for converting the grid voltage of the MOSFET into direct current voltage;
s3, when the grid voltage of the MOSFET Q2 is larger than the conducting voltage, the MOSFET Q2 is conducted,
s4, generating characteristic current by utilizing the voltage of the grid source two-electrode node of the Q2 and the parallel resistors R102 and R103; the characteristic current is superposed on the phase A loop;
s5, when the voltage of the node of the gate electrode and the source electrode of the MOSFET Q2 is smaller than the conducting voltage; MOSFET transistor Q2 is off.
The working principle and the effect of the technical scheme are as follows: the output of the TL_PWM_SET control signal is realized by controlling the on of the optocoupler; the grid voltage of the MOSFET is changed into direct current voltage by utilizing a voltage stabilizing circuit; when the grid voltage of the MOSFET is larger than the conducting voltage, conducting is realized; generating characteristic current through parallel resistors and superposing the characteristic current on the phase A loop; when the voltage of the gate-source electrode node of the MOSFET Q2 is smaller than the on voltage, the turn-off effect of the MOSFET Q2 is realized. These steps all help to achieve switching power supply operation and improve power conversion efficiency.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (9)
1. A circuit for an adjustable characteristic current based on a MOSFET switching voltage, the circuit comprising:
MCU system: outputting a TL_PWM_SET control signal to a MOSFET control module;
an input protection module: the method is used for line protection;
and a rectification module: for providing a loop voltage for the control circuit;
and the voltage stabilizing module is used for: changing the grid voltage of the MOSFET into a set direct-current voltage;
and the characteristic current sampling module is used for: for obtaining a characteristic current;
MOSFET control module: receiving a control signal of the MCU system and controlling the on-off of the MOSFET; meanwhile, the voltage stabilizing module is connected to acquire voltage;
the input protection module is sequentially connected with the rectifying module, the voltage stabilizing module and the MOSFET control module; the MOSFET control module is connected with the MCU system; the characteristic current sampling module is connected with the MOSFET Q2.
2. An adjustable characteristic current signal circuit based on MOSFET switching voltage according to claim 1, wherein the MCU system comprises: chip, crystal oscillator and electric capacity.
3. The adjustable characteristic current signal circuit based on the switching voltage of the MOSFET according to claim 1, wherein the input protection module comprises a parallel resistor formed by R88 and R89 and a parallel resistor formed by R93 and R94; the input ends of R88 and R89 are connected with A phase voltage, and the output ends are connected with a voltage stabilizing module; the input ends of R93 and R94 are connected with rated voltage, and the output ends are connected with a voltage stabilizing module.
4. An adjustable characteristic current signal circuit based on MOSFET switching voltage according to claim 1, wherein the characteristic current sampling module comprises parallel resistors R102 and R103; one ends of R103 and R102 are grounded, the other ends are connected with the grid electrode of the MOSFET Q2 through a capacitor, and the other ends are also directly connected with the source electrode of the MOSFET Q2.
5. The adjustable characteristic current signal circuit based on the switching voltage of the MOSFET according to claim 1, wherein the MOSFET control module comprises an optical coupling OP1, a blocking protection capacitor C96 and a voltage stabilizing tube D18; the positive electrode of the optical coupling OP1 input end is connected with the positive electrode of a 3.3V power supply; the negative electrode of the input end of the optical coupling OP1 is connected with the C electrode of the triode Q3 through a resistor; the E electrode of the triode Q3 is grounded; the TL_PWM_SET output end of the MCU system is connected with the B pole of the triode Q3 through a resistor and the blocking protection capacitor C96; the output end of the voltage stabilizing tube D18 is connected with the grid electrode of the MOSFET Q2.
6. An adjustable characteristic current signal circuit based on a MOSFET switching voltage according to claim 1, wherein the rectifying module is a full wave rectifier comprising diodes VD1, VD2, VD3 and VD4.
7. The adjustable characteristic current signal circuit based on MOSFET switching voltage according to claim 1, wherein the circuit further comprises a detection module comprising a PWM signal detection module and a MOSFET switching frequency detection module; the PWM signal detection module is used for detecting the frequency and the duty ratio of PWM.
8. The adjustable characteristic current signal circuit based on the switching voltage of the MOSFET according to claim 7, wherein the delay delta T is calculated according to the PWM signal detection module and the MOSFET switching frequency detection module; determining whether the signal output is correct or not according to the frequency and the duty ratio, and reminding the MCU system to adjust if the signal output is incorrect; in one PWM period, the required duty ratio is D (D is more than or equal to 0 and less than or equal to 1), the PWM period is T, the switching frequency of the MOSFET is f, the delay time delta T= |1/f-T| is adjusted within delta T before the start of the next period if the change of the frequency and the duty ratio of the PWM is detected, and an alarm prompt is sent to prompt the background to detect components if the switching frequency or the PWM frequency is still unstable within T+2delta T time after the adjustment or the change occurs after the stabilizing time is less than 3T+2delta T.
9. A method of operating an adjustable characteristic current based on a MOSFET switching voltage, the method comprising:
s1, the MCU outputs a TL_PWM_SET control signal according to a SET switching frequency, and when the TL_PWM_SET signal is at a high level, the optical coupler OP1 is controlled to be conducted;
s2, the output of the voltage stabilizing circuit is connected with the input of the MOSFET control circuit, and the voltage stabilizing circuit is used for converting the grid voltage of the MOSFET into direct current voltage;
s3, when the grid voltage of the MOSFET Q2 is larger than the conducting voltage, the MOSFET Q2 is conducted,
s4, generating characteristic current by utilizing the voltage of the grid source two-electrode node of the Q2 and the parallel resistors R102 and R103; the characteristic current is superposed on the phase A loop;
s5, when the voltage of the node of the gate electrode and the source electrode of the MOSFET Q2 is smaller than the conducting voltage; MOSFET transistor Q2 is off.
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| DE4202251A1 (en) * | 1992-01-16 | 1993-07-22 | Schroecker Rainer | CIRCUIT ARRANGEMENT FOR CONTROLLING FIELD-CONTROLLED CIRCUIT BREAKERS |
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