CN113037071A - Soft start device of PFC circuit, PFC circuit and electrical apparatus - Google Patents

Soft start device of PFC circuit, PFC circuit and electrical apparatus Download PDF

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Publication number
CN113037071A
CN113037071A CN202110255133.3A CN202110255133A CN113037071A CN 113037071 A CN113037071 A CN 113037071A CN 202110255133 A CN202110255133 A CN 202110255133A CN 113037071 A CN113037071 A CN 113037071A
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current
bus voltage
voltage
input
stage
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CN113037071B (en
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付永新
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Qingdao Hisense Hitachi Air Conditioning System Co Ltd
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Qingdao Hisense Hitachi Air Conditioning System Co Ltd
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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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/36—Means for starting or stopping 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
    • H02M1/14—Arrangements for reducing ripples from dc input or output
    • 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
    • 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
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • 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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  • Power Engineering (AREA)
  • Rectifiers (AREA)

Abstract

The invention discloses a soft start device of a PFC circuit, the PFC circuit and an electric appliance, wherein the soft start device comprises: the processing module sequentially starts the PFC circuit according to the set first stage, second stage, and third stage, and is specifically configured to: in the first stage, the control voltage outer ring and the current inner ring are respectively opened, and the bus voltage and the input inductive current are controlled in an open loop mode according to the set first bus voltage instruction and the calculated duty ratio instruction; in the second stage, the voltage outer ring is controlled to be open-loop, and the bus voltage and the input inductive current are controlled through the current inner ring according to the set input current instruction; and in the third stage, the bus voltage and the input inductive current are controlled through the voltage outer ring and the current inner ring according to the second bus voltage command. The invention can gradually start the PFC circuit in multiple stages, slow down the large pulse current in the starting process, reduce the circuit cost and improve the reliability of the control circuit.

Description

Soft start device of PFC circuit, PFC circuit and electrical apparatus
Technical Field
The invention relates to the technical field of PFC circuit control, in particular to a soft start device and circuit of a PFC circuit and an electric appliance.
Background
The variable frequency air conditioner generally increases a Power Factor Correction (PFC) control technology so as to improve the Power Factor, adjust harmonic current and reduce the influence of the air conditioner on a Power grid.
As shown in fig. 1, the PFC (Power Factor Correction) circuit is a typical PFC circuit, which adopts a boost topology, performs bridge rectification on an ac voltage by using a rectification circuit to obtain a voltage Vac, and supplies the voltage Vac to an inductor, and controls on and off of a switching tube to make an input current Iac follow the change of Vac. The working principle of the circuit is as follows: the inductor stores energy when the switching tube is on, and charges a large filter capacitor through the diode with the stored energy when the switching tube is off, and the filter capacitor can output a smoothed and stabilized bus voltage Vdc.
Referring to fig. 1, since the rear end of the circuit has a large filter capacitor, a bus has a large charging current at the moment of power-on, which may have a large impact on a rectifier device on the circuit, and may seriously damage the rectifier device.
In the prior art, a scheme for realizing soft start of a circuit is provided by controlling the on-off of a relay in a soft start relay circuit through a controller (such as a digital chip), the direct current bus voltage of a PFC circuit is detected through the controller, and when the voltage of the PFC bus rises to be high enough, the controller sends a signal to pull in a relay and short out a soft start resistor, so that safe and reliable soft start of a high-power supply is realized.
The soft start scheme has the disadvantages that a starting resistor needs to be added in the circuit, the starting resistor is connected in series in the circuit when the circuit is powered on, and the relay short circuit starting resistor is matched after charging is finished to realize the soft start at the moment of power on.
Disclosure of Invention
An objective of an embodiment of the present invention is to provide a soft start device for a PFC circuit, which gradually starts the PFC circuit in multiple stages, slows down a large pulse current during a start-up process, reduces a circuit cost, and improves a reliability of a control circuit.
In order to realize the purpose of the invention, the invention is realized by adopting the following technical scheme:
the application relates to a soft start device of a PFC circuit, which is characterized by comprising:
the processing module sequentially starts the PFC circuit according to the set first stage, second stage, and third stage, and is specifically configured to:
in the first stage, a control voltage outer ring and a current inner ring are respectively opened, and the open loop control of the bus voltage and the input inductive current is carried out according to a set first bus voltage instruction and a calculated duty ratio instruction, wherein the duty ratio instruction is related to the first bus voltage instruction;
in the second stage, the voltage outer ring is controlled to be open-loop, and the bus voltage and the input inductive current are controlled through the current inner ring according to a set input current instruction;
and in the third stage, the bus voltage and the input inductive current are controlled through the voltage outer ring and the current inner ring according to a set second bus voltage instruction.
The utility model relates to a soft start device of PFC circuit for control PFC circuit three-step progressive opens, in the first stage, control voltage outer loop and electric current inner loop are the equal open loop, through first bus voltage instruction and duty ratio instruction open loop control bus voltage and input inductance current, in the second stage, control current inner loop closed loop and voltage outer loop open loop, through the strict control electric current of input current instruction, in the third stage, control current inner loop and voltage outer loop are the equal closed loop, through second bus voltage instruction strict control bus voltage, multi-step progressive slowly starts PFC circuit, make PFC circuit slowly transition to steady state, avoid producing big impulse current, reduce the current impact to switch tube and rectifier.
The soft start device provided by the invention can realize the soft start of the PFC circuit without starting a resistor and a relay, thereby reducing the cost of a hardware circuit and improving the reliability of a control circuit.
In this application, the first bus voltage command is:
Figure 265995DEST_PATH_IMAGE001
；
the duty ratio command D is:
Figure 770051DEST_PATH_IMAGE002
；
Figure 621332DEST_PATH_IMAGE003
is the average value of the rectified input voltage,I ac in order to input the instantaneous value of the inductor current,
Figure 582335DEST_PATH_IMAGE004
is the average value of the input inductor current,V 1 andV 2 respectively the minimum and maximum values of the bus voltage in the first phase,t 1 is the duration of the first phase and is,tindicating the time to enter the first phase.
In this application, the soft start apparatus further includes:
a current setting unit for setting a first current thresholdI 1 A second current thresholdI 2 And a third current thresholdI 3 ；
A voltage setting unit for settingV 1 、V 2 Bus voltage thresholdV 3 And bus voltage thresholdV 4 ；
Wherein in the first phase, the peak value of the input inductance current is greater than or equal toI 1 And is less thanI 2 And the bus voltage is greater than or equal toV 1 And is less thanV 2 ；
Wherein in the second stage, the peak value of the input inductive current is greater than or equal toI 2 And is less thanI 3 And the bus voltage is greater than or equal toV 2 And is less thanV 3 ；
Wherein at the placeIn the third stage, the peak value of the input inductive current is greater than or equal toI 3 And the bus voltage is greater than or equal toV 3 And is less thanV 4 。
In the present application, the input current command is:
Figure 355119DEST_PATH_IMAGE005
，
Figure 161401DEST_PATH_IMAGE006
；
wherein,f 0 in order to input the frequency of the power supply,θ 1 the phase deviation of the alternating current power supply voltage entering the second stage;t 2 is the duration of the second phase and is,tindicating the time of entry into the second phase.
In this application, the second bus voltage command is:
Figure 336030DEST_PATH_IMAGE007
；
wherein,t 3 is the duration of the third phase,tindicating the time to enter the third phase.
In this application, the soft start apparatus further includes:
a current sampling unit for sampling an input inductor current;
a first voltage sampling unit for sampling the rectified input voltage;
the second voltage sampling unit is used for sampling the bus voltage;
the current sampling unit, the first voltage sampling unit and the second voltage sampling unit have the same sampling time and sampling period.
In this application, the processing module is further configured to:
at the input inductance current is reduced toI 1 When, or the bus voltage is reduced toV 1 And when the PFC circuit is started, the PFC circuit is forbidden to be started.
The application also provides a PFC circuit, which comprises the soft start device, and can realize the soft start of the multi-stage PFC circuit, slowly establish the stable process of the PFC circuit, avoid the generation of large pulse current in the start process and reduce the damage to devices.
The application further provides an electric appliance, which comprises the PFC circuit, and the harmonic current can be adjusted while the power factor is improved, so that the influence of the electric appliance on a power grid is reduced.
In the present application, the electric appliance includes: air conditioner, refrigerator, electric water heater, washing machine, TV set.
Other features and advantages of the present invention will become more apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a prior art PFC circuit;
fig. 2 is a control schematic diagram of an embodiment of a soft start device of a PFC circuit according to the present invention;
fig. 3 is a waveform diagram of a bus voltage, an input inductor current envelope, and an input ac voltage during a soft start process of an embodiment of a soft start apparatus of a PFC circuit according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.
All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.
In the description of the present invention, it should be noted that the terms "mounted," "connected," and "connected" are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected unless otherwise explicitly stated or limited. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art. In the foregoing description of embodiments, the particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.
The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
PFC circuit
Referring to fig. 1, a conventional PFC circuit is shown.
The PFC circuit comprises an alternating current power supply AC, a rectifier bridge BG1, an inductor L, a switching tube, a diode D4, an electrolytic capacitor E1 and an electrolytic capacitor E2.
A first alternating current input end of the rectifier bridge BG1 is connected to a zero line end ACN of an alternating current power supply AC, and a second alternating current input end of the rectifier bridge BG1 is connected to a phase line end ACL of the alternating current power supply AC.
The positive electrode of the direct-current side of the rectifier bridge BG1 is connected to one end of an inductor L, the other end of the inductor L is divided into two paths, one path is connected to the collector of the switching tube IGBT, and the other path is connected to the anode of a diode D4.
The cathode of the diode D4 is the output end of the PFC circuit, and the electrolytic capacitor E1 and the electrolytic capacitor E2 are both connected between the cathode of the diode D4 and the ground.
In the prior art, a control scheme for a PFC circuit mainly adopts double closed-loop control of a voltage outer loop and a current inner loop.
The current inner loop has the function of forcing the input current to track the waveform of the input voltage and form a sine waveform; the voltage outer loop functions to maintain the output voltage at a level higher than the peak value of the input voltage, and may function to stabilize the output voltage.
In the application, by using a double closed-loop control scheme of the PFC circuit, the PFC circuit adopts different starting strategies according to different set stages, so that the PFC circuit is slowly started, and the generation of large pulse impact current is avoided.
Soft starting device
Fig. 2 shows a control block diagram of the soft start device of the PFC circuit in the present application. Fig. 3 shows waveforms of the bus voltage, the input inductor current filter envelope, and the input ac voltage during soft start of an embodiment of a soft start apparatus of a PFC circuit.
The control process of the soft start of the PFC circuit is described in detail with reference to fig. 2 and 3.
The control processes described below are all performed by the processing module.
In the application, the first phase, the second phase and the third phase of the soft start of the PFC circuit are divided according to the test effect.
First stage
In the first stage, the control voltage outer ring and the current inner ring are both opened, and the bus voltage and the input inductive current are controlled according to the set first bus voltage instruction and the calculated duty ratio instruction.
Wherein the duty cycle command is associated with the first bus voltage command.
The input end of the voltage outer loop receives the first bus voltage command and the sum of bus voltage negative feedback, wherein the bus voltage negative feedback is the negative feedback of the sampled bus voltage.
The input end of the current inner loop receives the sum of the output quantity of the voltage outer loop output by the voltage outer loop and the negative feedback of the input current, wherein the negative feedback of the input current is the negative feedback of the sampled input inductive current.
Setting a first bus voltage thresholdV 1 And a second bus voltage thresholdV 2 Defining a bus voltage of a first stage and setting a peak value of an input inductor current to be equal to or greater than a first current threshold valueI 1 And is less than or equal to the second current thresholdI 2 。
In this phase, the bus voltage is at a first bus voltage thresholdV 1 And a second bus voltage thresholdV 2 The input inductance current is non-sinusoidal half-wave current with peak value of the half-wave current being equal to or less than the first current threshold valueI 1 Gradually and slowly increasing but less than the second current thresholdI 2 。
In the stage, the system is completely in an open-loop state, the duty ratio is directly controlled through the first bus voltage command and the calculated duty ratio command, the impact of large pulse current caused by the closed-loop system is prevented, and the dynamic response process in the stage can have large signal adjustment.
In this phase, the first bus voltage commandV ref Determined according to the following formula:
Figure 202355DEST_PATH_IMAGE001
。
V 1 andV 2 respectively the minimum and maximum values of the bus voltage in the first phase,t 1 is the duration of the first stage and is,tindicating the time to enter the first phase.
The duty command D is determined according to the following formula:
Figure 963900DEST_PATH_IMAGE002
whereinV ref Is the value obtained in the first bus voltage command as described above.
Figure 573873DEST_PATH_IMAGE003
The rectified input voltage may be sampled by a voltage sampling unit for an average value of the rectified input voltage, and the sampled input voltage may be calculatedV ac Average value of (a).
I ac To input the instantaneous value of the inductor current, the current in the loop may be sampled by a current sampling unit.
The current sampling unit may be a resistor (e.g., R in fig. 1) for detecting current connected in series with the PFC circuitS）。
Figure 806271DEST_PATH_IMAGE004
The average value of the input inductive current can be calculated by calculating the average value after samplingI ac Obtaining the average value of (a).
The duty ratio instruction is input to the pulse carrier modulation module, and a modulation PWM signal is output, wherein the PWM signal is a pulse signal for controlling the on/off of a switch tube in the PFC circuit.
In the phase, the duty ratio output is controlled within a controllable range by setting the first bus voltage instruction, and the current cannot have large current impact.
In the stage, the voltage outer ring and the current inner ring are in a full open loop state, and the bus voltage is controlled to reach a second bus voltage threshold valueV 2 The PFC circuit then enters the second stage.
In the second stage, the effective value (or average value) of the inductor current will increase, i.e. the peak value of the corresponding inductor current will also increaseBut peak limited to the second current threshold in the second phaseI 2 And a third current thresholdI 3 And ensuring that no large current can occur.
If the load decreases, the effective (or average) value of the inductor current decreases to the first current thresholdI 1 When, or bus voltage decreases to the first bus voltage thresholdV 1 And when the starting is finished, the soft start process of the PFC circuit is closed, and the PFC circuit enters a pre-start state.
It should be noted that, in the following description,V 1 andV 2 respectively a first bus voltage threshold and a second bus voltage threshold set for the bus voltage in the first phase.
First bus voltage thresholdV 1 Second bus voltage thresholdV 2 First current thresholdI 1 And a second current thresholdI 2 Can be adjusted by testing the effect.
The bus voltage can be obtained through a voltage sampling unit, and the voltage sampling unit can be designed into a voltage division circuit.
Second stage
In the second stage, the voltage outer ring is controlled to be open and the current inner ring is controlled to be closed, and the bus voltage and the input inductive current are controlled according to the set input current instruction.
Setting a second bus voltage thresholdV 2 And a third bus voltage thresholdV 3 The bus voltage in the second stage is defined, and as described above, the peak values of the input inductor currents are set to be greater than or equal to the first current threshold valueI 1 And is less than or equal to the second current thresholdI 2 。
In this phase, the bus voltage is from the second bus voltage thresholdV 2 Gradually increasing to a third bus voltage thresholdV 3 。
This stage is aimed at a strict control of the inductor current, setting a second current thresholdI 2 And a third current thresholdIThe peak value of the inductive current is at the second current threshold valueI 2 And a third current thresholdI 3 To change between.
In this stage, the system is in a single-current inner loop closed loop state, and the input current command is set to control the bus voltage and the input inductive current.
Wherein the input end of the voltage outer loop receives bus voltage negative feedback, wherein the bus voltage negative feedback is negative feedback of the sampled bus voltage.
The input end of the current inner loop receives the sum of an input current command and input current negative feedback, wherein the input current negative feedback is the negative feedback of the sampled input inductance current.
The input current command is set as follows.
Figure 109076DEST_PATH_IMAGE005
，
Figure 590873DEST_PATH_IMAGE006
。
Wherein,f 0 in order to input the frequency of the power supply,θ 1 the phase deviation of the alternating current power supply voltage entering the second stage;k 1 is a current command coefficient, and is a second current thresholdI 2 And a third current thresholdI 3 The current of (a) is linearly set to a value,t 2 the duration of the second phase is the duration of the second phase,tindicating the time to enter the second phase.
The purpose of the stage is to make the input inductive current execute according to the input current instruction strictly, so that the input inductive current is a sinusoidal half-wave current following the input current instruction, and the peak value is lower than a third current threshold valueI 3 。
In the second stage, the input inductive current is a half-wave current of sine wave, and the bus voltage is still a fluctuating direct current voltage.
The third stage
In the third stage, the voltage outer ring and the current inner ring are controlled to be closed, the circuit enters double closed-loop control, and the bus voltage and the input inductive current are controlled according to the set second bus voltage instruction.
In the second phase, the input inductor current is already sinusoidal with a half-wave current, and thus, in the third phase, no current threshold is set.
The purpose of this stage is to strictly control the bus voltage, setting a third bus voltage thresholdV 3 And a fourth bus voltage thresholdV 4 The bus voltage of the third stage is defined.
Since this stage is in a dual closed loop control system, a bus voltage command must be set to control the bus voltage and the input inductor current.
The input end of the voltage outer loop receives the sum of the second bus voltage command and bus voltage negative feedback, wherein the bus voltage negative feedback is negative feedback of the sampled bus voltage.
The input end of the current inner loop receives the output quantity of the voltage outer loop output by the voltage outer loop and the negative feedback of the input inductive current, wherein the negative feedback of the input inductive current is the negative feedback of the sampled input inductive current.
The second bus voltage command satisfies the following equation:
Figure 4537DEST_PATH_IMAGE007
；
wherein,V ref ' is a third bus voltage thresholdV 3 To a fourth bus voltage thresholdV 4 A linear voltage set-point in between,t 3 the duration of the third phase is the duration of the third phase,tindicating the time to enter the third phase.
In this stage, as the load increases, the input inductive current sinusoidal degree increases, the power factor also increases, and the bus voltage is a dc voltage that is more stable following the second bus voltage command, so that the PFC circuit can be started slowly, and the PFC circuit is transitioned slowly to a stable state.
When the bus voltage reaches a fourth bus voltage thresholdV 4 At this point, the soft start process of the PFC circuit ends.
After the third stage, the input inductor current is a half-wave current of sine, and the bus voltage is a stable direct current voltage.
In the present application, the first bus voltage thresholdV 1 Second bus voltage thresholdV 2 Third bus voltage thresholdV 3 And a fourth bus voltage thresholdV 4 The voltage is approximately linearly increased and is set by the voltage setting unit.
First current thresholdI 1 A second current thresholdI 2 And a third current thresholdI 3 Also increases linearly and the magnitude is set by the current setting unit.
The soft start device realizes the soft start of the PFC circuit by setting different control instructions in three stages in sequence, and the soft start device in the first stage is according to a first bus voltage instructionV ref And duty cycle commandDStarting, in the second stage according to the input current instructionI ref Starting up, in the third stage according to the second bus voltage instructionV ref 'And starting, the bus voltage and the input inductive current are controlled in stages, stable bus voltage and sinusoidal input inductive current are slowly realized, large pulse current is prevented from being generated in the starting process of the PFC circuit, and damage to a rectifier and a switching tube is reduced.
The soft start device can realize the soft start of the PFC circuit without starting a resistor and a relay, thereby reducing the cost of the circuit and improving the reliability of the control circuit.
The invention also provides a PFC circuit corresponding to the soft start device of the PFC, which comprises the soft start device of the PFC circuit.
The PFC circuit can realize soft start, and the hardware circuit has low input cost and maintenance cost, so that the power factor is improved, large pulse current can be prevented from being generated when the PFC circuit is started, and the damage to a rectifier and a switching tube is reduced.
The application also provides an electric appliance corresponding to the PFC circuit, which comprises the PFC circuit.
In the present application, the appliance may be an air conditioner, a refrigerator, an electric water heater, a washing machine, a television, or the like.
By arranging the PFC circuit, the power factor of the electric appliance can be improved, so that the utilization efficiency of the electric energy of the power grid is improved.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions.

Claims (10)

1. A soft start device for a PFC circuit, comprising:
the processing module sequentially starts the PFC circuit according to the set first stage, second stage, and third stage, and is specifically configured to:
in the first stage, a control voltage outer ring and a current inner ring are respectively opened, and the open loop control of the bus voltage and the input inductive current is carried out according to a set first bus voltage instruction and a calculated duty ratio instruction, wherein the duty ratio instruction is related to the first bus voltage instruction;
in the second stage, the voltage outer ring is controlled to be open-loop, and the bus voltage and the input inductive current are controlled through the current inner ring according to a set input current instruction;
and in the third stage, the bus voltage and the input inductive current are controlled through the voltage outer ring and the current inner ring according to a second bus voltage setting instruction.
2. The soft start apparatus of claim 1,
the first bus voltage command is:
Figure DEST_PATH_IMAGE002
；
the duty ratio command D is:
Figure DEST_PATH_IMAGE004
；
Figure DEST_PATH_IMAGE006
is the average value of the rectified input voltage,I ac in order to input the instantaneous value of the inductor current,
Figure DEST_PATH_IMAGE008
is the average value of the input inductor current,V 1 andV 2 respectively the minimum and maximum values of the bus voltage in the first phase,t 1 is the duration of the first phase and is,tindicating the time to enter the first phase.
3. The soft-start apparatus of claim 2, further comprising:
a current setting unit for setting a first current thresholdI 1 A second current thresholdI 2 And a third current thresholdI 3 ；
A voltage setting unit for settingV 1 、V 2 Bus voltage thresholdV 3 And bus voltage thresholdV 4 ；
Wherein in the first phase, the peak value of the input inductance current is greater than or equal toI 1 And is less thanI 2 And the bus voltage is greater than or equal toV 1 And is less thanV 2 ；
Wherein in the second stage, the peak value of the input inductive current is greater than or equal toI 2 And is less thanI 3 And the bus voltage is greater than or equal toV 2 And is less thanV 3 ；
Wherein in the third stage, the peak value of the input inductive current is greater than or equal toI 3 And the bus voltage is greater than or equal toV 3 And is less thanV 4 。
4. A soft start apparatus as claimed in claim 3,
the input current command is:
Figure DEST_PATH_IMAGE010
，
Figure DEST_PATH_IMAGE012
；
wherein,f 0 in order to input the frequency of the power supply,θ 1 the phase deviation of the alternating current power supply voltage entering the second stage;t 2 is the duration of the second phase and is,tindicating the time of entry into the second phase.
5. A soft start apparatus as claimed in claim 3,
the second bus voltage command is:
Figure DEST_PATH_IMAGE014
；
wherein,t 3 is the duration of the third phase,twhen entering the third stageAnd (3) removing the solvent.
6. The soft start apparatus of any one of claims 1 to 5, further comprising:
a current sampling unit for sampling an input inductor current;
a first voltage sampling unit for sampling the rectified input voltage;
the second voltage sampling unit is used for sampling the bus voltage;
the current sampling unit, the first voltage sampling unit and the second voltage sampling unit have the same sampling time and sampling period.
7. The soft-start apparatus of claim 3, wherein the processing module is further configured to:
at the input inductance current is reduced toI 1 When, or the bus voltage is reduced toV 1 And when the PFC circuit is started, the PFC circuit is forbidden to be started.
8. A PFC circuit comprising a soft start apparatus as claimed in any one of claims 1 to 7.
9. An electrical appliance comprising the PFC circuit of claim 8.
10. The electric appliance according to claim 9, characterized in that it comprises: air conditioner, refrigerator, electric water heater, washing machine, TV set.
CN202110255133.3A 2021-03-09 2021-03-09 Soft start device of PFC circuit, PFC circuit and electrical apparatus Active CN113037071B (en)

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CN104158244A (en) * 2014-08-06 2014-11-19 上海凌阳科技有限公司 First-order constant current mode charging circuit and constant current-constant voltage mode switchable charging circuit
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WO2023141899A1 (en) * 2022-01-27 2023-08-03 Redisem Ltd. Power converter control circuit and method

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