CN110311547B - PFC circuit and air conditioner - Google Patents

PFC circuit and air conditioner Download PDF

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Publication number
CN110311547B
CN110311547B CN201910622849.5A CN201910622849A CN110311547B CN 110311547 B CN110311547 B CN 110311547B CN 201910622849 A CN201910622849 A CN 201910622849A CN 110311547 B CN110311547 B CN 110311547B
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Prior art keywords
pfc
circuit
input
switch
output end
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CN110311547A (en
Inventor
胡荏
时崎久
王明明
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Midea Group Co Ltd
GD Midea Air Conditioning Equipment Co Ltd
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Midea Group Co Ltd
GD Midea Air Conditioning Equipment 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
    • H02M1/42—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

Abstract

The invention discloses a PFC circuit and an air conditioner, wherein the PFC circuit comprises: one end of the reactor is connected with a live wire end L of the alternating current power supply; the input end of the rectifying circuit is connected with the other end of the reactor; the PFC driving circuit outputs a corresponding PFC driving signal according to the received PFC control signal; the controlled end of the PFC switch circuit is connected with the output end of the PFC drive circuit, and the first input/output end of the PFC switch circuit is connected with the other end of the reactor; a second input/output end of the PFC switch circuit is connected with a zero line end N of the alternating current power supply; and the PFC switch circuit is used for outputting the power supply accessed by the first input/output end to the second input/output end according to the PFC driving signal or outputting the power supply accessed by the second input/output end to the first input/output end. The invention solves the problems of large loss and low energy efficiency of the PFC circuit.

Description

PFC circuit and air conditioner
Technical Field
The invention relates to the technical field of electronic circuits, in particular to a PFC circuit and an air conditioner.
Background
A Power Factor Correction (PFC) circuit is generally introduced into existing electronic Power equipment, so that on one hand, the utilization rate of a Power supply to mains supply can be improved when alternating current is converted into direct current through the PFC circuit, and the electric energy loss in the conversion process is reduced, so that energy can be saved; on the other hand, harmonic pollution in the power grid can be reduced through the PFC circuit.
At present, a PFC circuit generally adopts a bridge stack to convert alternating current into direct current, and then adopts a BOOST circuit to BOOST, so as to realize power factor correction, however, the bridge stack has a large volume and large on-state loss, which easily causes large loss and low energy efficiency of the PFC circuit.
Disclosure of Invention
The invention mainly aims to provide a PFC circuit and an air conditioner, and aims to solve the problems of high loss and low energy efficiency of the PFC circuit.
In order to achieve the above object, the present invention provides a PFC circuit, including:
one end of the reactor is connected with a live wire end of an alternating current power supply;
the input end of the rectifying circuit is connected with the other end of the reactor;
the PFC driving circuit outputs a corresponding PFC driving signal according to the received PFC control signal;
the controlled end of the PFC switch circuit is connected with the output end of the PFC driving circuit, and the first input/output end of the PFC switch circuit is connected with the other end of the reactor; a second input/output end of the PFC switch circuit is connected with a zero line end of the alternating current power supply; the PFC switch circuit is used for outputting the power supply accessed by the first input/output end to the second input/output end according to the PFC driving signal, or outputting the power supply accessed by the second input/output end to the first input/output end.
Optionally, the PFC driving circuit includes a first driving switch, a first resistor, a second resistor, and a signal isolation device, where a first end of the first resistor is a controlled end of the PFC driving circuit, and a second end of the first resistor is interconnected with the controlled end of the first driving switch and a first end of the second resistor; the input end of the first driving switch and the second end of the second resistor are connected with a first direct current power supply, the output end of the first driving switch is connected with the input end of the signal isolation device, and the output end of the signal isolation device is the output end of the PFC driving circuit.
Optionally, the PFC switch circuit includes a first switch tube and a first diode, the controlled end of the first switch tube is the controlled end of the PFC switch circuit, the input end of the first switch tube is the first input/output end of the PFC switch circuit, the output end of the first switch tube is connected to the anode of the first diode, and the cathode of the first diode is the second input/output end of the PFC switch circuit.
Optionally, the first switch tube is a MOS tube or an IGBT.
Optionally, the PFC switch circuit includes a second switch tube and a second diode, a controlled end of the second switch tube is a controlled end of the PFC switch circuit, an anode of the second diode is a first input/output end of the PFC switch circuit, and a cathode of the second diode is connected to an input end of the second switch tube; the output end of the second switch tube is a second input/output end of the PFC switch circuit.
Optionally, the second switch tube is a MOS tube or an IGBT.
Optionally, the PFC switch circuit includes a third switch tube and a fourth switch tube, a controlled end of the third switch tube and a controlled end of the fourth switch tube are connected to the output end of the PFC driver circuit, a first conductive end of the third switch tube is a first input/output end of the PFC switch circuit, a second conductive end of the third switch tube is connected to a first conductive end of the fourth switch tube, and a second conductive end of the fourth switch tube is a second input/output end of the PFC switch circuit.
Optionally, the PFC switch circuit further includes a third diode and a fourth diode, an anode of the third diode is connected to the first conductive terminal of the fourth switch tube, and a cathode of the third diode is connected to the reactor; and the anode of the fourth diode is connected with the second conductive end of the third switching tube, and the cathode of the fourth diode is connected with the live wire end of the alternating current power supply.
Optionally, the PFC circuit further includes a tank filter circuit, and an input end of the tank filter circuit is connected to an output end of the rectifier circuit.
The invention also provides an air conditioner which comprises the PFC circuit.
The PFC circuit outputs a corresponding PFC driving signal according to a received PFC control signal to drive the PFC switch circuit to work, and accesses the AC power output by the reactor through the first input/output end and then outputs the AC power to the second input/output end according to the PFC driving signal, or outputs the AC power accessed by the second input/output end to the first input/output end and the reactor, so that the waveform of the input current of the PFC circuit follows the waveform of the input voltage, and the power factor correction of the accessed AC power is realized. The invention does not need to arrange a rectifier bridge and corrects the power factor of the accessed alternating current power supply, thereby solving the problems of large volume of a bridge stack, large on-state loss, easy loss of a PFC circuit and low energy efficiency.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
Fig. 1 is a schematic diagram of functional modules of a PFC circuit according to an embodiment of the present invention;
fig. 2 is a schematic circuit diagram of another embodiment of a PFC circuit according to the present invention;
fig. 3 is a schematic circuit diagram of a PFC circuit according to another embodiment of the present invention;
fig. 4 is a schematic circuit diagram of a PFC circuit according to another embodiment of the present invention.
The reference numbers illustrate:
reference numerals Name (R) Reference numerals Name (R)
10 Rectifying circuit U1 First driving switch
20 PFC drive circuit U2 Signal isolation device
30 PFC switch circuit R1～R2 First to second resistors
40 Energy storage filter circuit Q1～Q4 First to fourth switching tubes
L1 Electric reactor D1～D4 First to fourth diodes
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
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.
It should be noted that, if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indications are changed accordingly.
In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is 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 at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
The invention provides a PFC circuit.
Referring to fig. 1, in an embodiment of the present invention, the PFC circuit includes:
a reactor L1, one end of the reactor L1 being connected to a live line terminal L of an ac power supply;
a rectifier circuit 10, an input end of which is connected to the other end of the reactor L1;
the PFC driving circuit 20 outputs a corresponding PFC driving signal according to the received PFC control signal;
a PFC switch circuit 30, a controlled terminal of the PFC switch circuit 30 being connected to the output terminal of the PFC drive circuit 20, and a first input/output terminal of the PFC switch circuit 30 being connected to the other terminal of the reactor L1; a second input/output end of the PFC switch circuit 30 is connected to a zero line end N of the ac power supply; the PFC switch circuit 30 is configured to output the power supply accessed by the first input/output terminal to the second input/output terminal according to the PFC driving signal, or output the power supply accessed by the second input/output terminal to the first input/output terminal.
In this embodiment, the reactor L1 and the PFC switch circuit 30 form a PFC main circuit, which may be a boost PFC circuit, a buck PFC circuit, or a boost PFC circuit, and this embodiment may be a low-frequency active boost PFC circuit. One end of the reactor L1 is connected to the live wire end of the ac input terminal, and the other end is connected to the rectifier circuit 10, and the live wire end of the ac input terminal is connected to the second input/output terminal of the PFC switch circuit 30, respectively. The PFC circuit can be applied to circuit modules such as a switching power supply and a frequency converter, correspondingly, the PFC circuit can be arranged on an electric control board of the switching power supply or the electric control board provided with the frequency converter so as to output electric energy to an inverter circuit in the frequency converter. The electric control board is also provided with a main controller MCU, the main controller MCU can be a main controller MCU for controlling the work of devices such as a compressor, a fan and the like in the outdoor unit of the air conditioner, or the main controller MCU is a main controller MCU specially used for the control of the PFC circuit, the main controller MCU drives the PFC circuit with low frequency in the power frequency period of the alternating current power supply, and the work frequency can be 1 time or a few times. The PFC driving circuit 20 in the PFC circuit outputs a corresponding PFC driving signal according to a PFC control signal output by the outdoor unit main controller MCU based on the control of the outdoor unit main controller MCU. The power supply voltage of the control chip on the electronic control board is usually 3.3V or 5V, the voltage of the output PFC control signal is also usually 3.3V or 5V, and the switching tube in the PFC circuit is usually set as a relay or a power tube, and requires a driving voltage of 9V, 12V or higher to drive, for this purpose, the PFC driving circuit 20 is set to amplify the received PFC control signal and output the amplified PFC control signal to the PFC switching circuit 30. Specifically, the main controller MCU may be a high-level pulse PFC control signal and a low-level pulse PFC control signal, and when receiving the high-level pulse PFC control signal, the PFC driving circuit 20 outputs a driving signal to drive the PFC switching circuit 30 to be turned on, and when receiving the low-level pulse PFC control signal, the PFC driving circuit 20 outputs a driving signal to drive the PFC switching circuit 30 to be turned off. Alternatively, when receiving the pulse PFC control signal of the low level, the PFC driving circuit 20 outputs a driving signal to drive the PFC switching circuit 30 to turn on, and when receiving the pulse PFC control signal of the high level, the PFC driving circuit 20 outputs a driving signal to drive the PFC switching circuit 30 to turn off.
When the PFC switch circuit 30 is turned on, in the positive half cycle of the ac power supply, the ac power is supplied from the live line of the ac input terminal, is stored in the energy by the reactor L1, and is then output to the first input/output terminal of the PFC switch circuit 30 and then to the second input/output terminal of the PFC switch circuit 30; and during the negative half cycle of the alternating current power supply, the alternating current is accessed to the second input/output end of the PFC switch circuit 30 from the zero line of the alternating current input end, the first input/output end of the PFC switch circuit 30 is output to the reactor L1, and is output to the live wire of the alternating current input end after being stored with energy by the reactor L1. Or, during the positive half cycle of the ac power supply, the ac power is switched in from the live wire of the ac input terminal, stored in energy by the reactor L1, and then output to the first input/output terminal of the PFC switch circuit 30, and then output through the second input/output terminal of the PFC switch circuit 30; on the other hand, in the negative half cycle of the ac power supply, the PFC switching circuit 30 is turned off, so that the ac power supply is output to the rectifier circuit 10 through the reactor L1. Alternatively, the PFC switch circuit 30 is in an off state at the positive half cycle of the ac power supply; during the positive half cycle of the alternating current power supply, the alternating current is connected to the second input/output end of the PFC switch circuit 30 from the zero line of the alternating current input end, the first input/output end of the PFC switch circuit 30 is output to the reactor L1, and is output to the live wire of the alternating current input end after being stored with energy by the reactor L1. By the arrangement, power factor correction of the accessed alternating current power supply can be realized without a rectifier bridge, and the reduction of the power consumption of the PFC circuit is facilitated.
The rectifier circuit 10 may be implemented by two diodes connected in series in sequence, or may be implemented by four diodes, four diodes are taken as an example in the present embodiment, and the four diodes are respectively labeled as D41, D42, D43, and D44; the diodes D41 and D42 are connected in series and then connected in parallel with the other two diodes D43 and D44 connected in series. The reactor L1 is connected to a common end of two groups of diodes connected in series, cathodes of the two groups of diodes D41 and D43 connected in parallel are connected to a dc bus, and anodes of the diodes D42 and D44 are connected to a zero line end of an ac input end.
According to the PFC circuit, the PFC driving circuit 20 outputs a corresponding PFC driving signal according to a received PFC control signal so as to drive the PFC switch circuit 30 to work, and accesses the alternating current power output by the reactor L1 through the first input/output end according to the PFC driving signal and then outputs the alternating current power to the second input/output end, or outputs the alternating current power accessed by the second input/output end to the first input/output end and the reactor L1, so that the waveform of the input current of the PFC circuit follows the waveform of the input voltage, and power factor correction is performed on the accessed alternating current power. The invention does not need to arrange a rectifier bridge and corrects the power factor of the accessed alternating current power supply, thereby solving the problems of large volume of a bridge stack, large on-state loss, easy loss of a PFC circuit and low energy efficiency.
Referring to fig. 2 to 4, in an embodiment, the PFC driving circuit 20 includes a first driving switch U1, a first resistor R1, a second resistor R2 and a signal isolation device U2, a first end of the first resistor R1 is a controlled end of the PFC driving circuit 20, and a second end of the first resistor R1 is interconnected with the controlled end of the first driving switch U1 and a first end of the second resistor R2; the input end of the first driving switch U1 and the second end of the second resistor R2 are connected with a first direct current power supply VCC1, the output end of the first driving switch U1 is connected with the input end of the signal isolation device U2, and the output end of the signal isolation device U2 is the output end of the PFC driving circuit 20.
In this embodiment, first drive switch U1 can adopt the triode, the switch tube of MOS pipe realizes, and first drive switch U1 of this embodiment adopts the PNP triode to realize, and signal isolation device U2 can adopt opto-coupler, diode, relay, sensor etc. can realize that the component of signal isolation realizes, and this embodiment is optional for the opto-coupler, and wherein, the collecting electrode and the positive pole of the luminous coupling emitting diode of PNP triode are connected. The collector of the opto-coupler phototriode is connected with a second direct current power supply VCC2, the emitter is connected with the controlled end of the PFC switch circuit 30, and the opto-coupler also provides a driving power supply for the PFC switch circuit 30. Of course, in other implementations, the first driving switch U1 may also be implemented by using an NPN transistor, and the NPN transistor is connected to the cathode of the optocoupler light emitting diode. The components and connection relationship of the PFC driving circuit 20 may be adaptively changed according to a specific scheme, and are not limited herein. The PNP transistor is turned on when receiving the PFC control signal of the low level, thereby driving the optocoupler to be turned on and outputting a corresponding driving signal to the PFC switch circuit 30. The PNP transistor is turned off when receiving the PFC control signal of high level, thereby driving the optocoupler to be turned off, and further stopping outputting the corresponding driving signal to the PFC switch circuit 30.
Referring to fig. 2, in an embodiment, the PFC switch circuit 30 includes a first switch Q1 and a first diode D1, the controlled terminal of the first switch Q1 is the controlled terminal of the PFC switch circuit 30, the input terminal of the first switch Q1 is the first input/output terminal of the PFC switch circuit 30, the output terminal of the first switch Q1 is connected to the anode of the first diode D1, and the cathode of the first diode D1 is the second input/output terminal of the PFC switch circuit 30. In this embodiment, the PFC switch circuit 30 further includes a resistor R21 and a resistor R22, wherein the resistor R21 is serially connected between the output terminal of the PFC driving circuit 20 and the controlled terminal of the first switch transistor Q1; the resistor R22 is serially connected between the controlled terminal and the input terminal of the first switch transistor Q1. The resistor R21 is a current limiting resistor, and the resistor R22 is a bias resistor.
Further, in the above embodiment, the first switching transistor Q1 is a MOS transistor or an IGBT.
In this embodiment, when receiving a PFC control signal output by the main controller MCU, the PFC switch circuit 30 drives and controls the MOS transistor or the IGBT in the main circuit to be turned on, and the diode D1 connected in series therewith is also turned on, during a positive half cycle, the voltage of the live wire at the ac input end is positive with respect to the voltage of the neutral wire, and the current path of the main circuit is the live wire at the ac input end-the reactor L1- (FUSE 1) -the IGBT device (or MOS transistor) Q1-the first diode D1-the neutral wire at the ac input end; in a positive half period, the voltage of the zero line of the alternating current input end is positive relative to the voltage of the live line, no matter whether the MOS tube or the IGBT is conducted or not, the first diode D1 is in a cut-off state, and the PFC circuit does not work. By adjusting the pulse width, pulse frequency, etc. of the first switching tube Q1 output by the PFC driving circuit 20, the on-time, on-frequency, etc. of the first switching tube Q1 are further controlled, so as to implement power factor correction on the accessed ac power supply.
Referring to fig. 3, in an embodiment, the PFC switch circuit 30 includes a second switch Q2 and a second diode D2, the controlled terminal of the second switch Q2 is the controlled terminal of the PFC switch circuit 30, the anode of the second diode D2 is the first input/output terminal of the PFC switch circuit 30, and the cathode of the second diode D2 is connected to the input terminal of the second switch Q2; the output terminal of the second switching tube Q2 is a second input/output terminal of the PFC switching circuit 30. In this embodiment, the PFC switch circuit 30 further includes a resistor R23 and a resistor R24, wherein the resistor R23 is serially connected between the output terminal of the PFC driving circuit 20 and the controlled terminal of the second switch Q2; the resistor R24 is serially connected between the controlled terminal and the input terminal of the second switch tube Q2. The resistor R23 is a current limiting resistor, and the resistor R24 is a bias resistor.
Further, the second switching tube Q2 is a MOS tube or an IGBT.
In this embodiment, when receiving a PFC control signal output by the main controller MCU, the PFC switch circuit 30 drives and controls the MOS or IGBT in the main circuit to be turned on, the second diode D2 connected in series therewith is also turned on, the voltage of the zero line at the ac input end is positive with respect to the voltage of the live line in the negative half cycle, and the current path of the main circuit is the zero line-IGBT device (or MOS) Q1-the second diode D2-the reactor L1- (FUSE 1) -the live line at the ac input end; in the positive half period, the voltage of the live wire at the alternating current input end is positive relative to the voltage of the zero wire, and no matter whether the MOS tube or the IGBT is conducted or not, the second diode D2 is in a cut-off state, and the PFC circuit does not work. The power factor correction of the accessed alternating current power supply is realized by adjusting the pulse width, the pulse frequency and the like of the second switching tube Q2 output by the PFC driving circuit 20, and further controlling the conduction time, the conduction frequency and the like of the second switching tube Q2.
Referring to fig. 4, in an embodiment, the PFC switch circuit 30 includes a third switch tube Q3 and a fourth switch tube Q4, the controlled terminal of the third switch tube Q3 and the fourth switch tube Q4 are connected to the output terminal of the PFC driver circuit 20, the first conductive terminal of the third switch tube Q3 is a first input/output terminal of the PFC switch circuit 30, the second conductive terminal of the third switch tube Q3 is connected to the first conductive terminal of the fourth switch tube Q4, and the second conductive terminal of the fourth switch tube Q4 is a second input/output terminal of the PFC switch circuit 30.
In this embodiment, the third switch transistor Q3 and the fourth switch transistor Q4 may be MOS transistors or IGBTs, and the MOS transistors do not need anti-parallel diodes (power type), so that the size of the circuit board can be reduced and the heat dissipation efficiency of the power transistors can be improved. In some high power applications, IGBT may be used. When the third switching tube Q3 and the fourth switching tube Q4 are implemented by using IGBTs, the third switching tube Q3 and the fourth switching tube Q4 are arranged oppositely, that is, the emitter of the third switching tube Q3 is connected with the emitter of the fourth switching tube Q4. In this embodiment, the PFC switch circuit 30 further includes a resistor R25, a resistor R26, a resistor R27, and a resistor R28, wherein the resistor R25 is serially connected between the output terminal of the PFC driver circuit 20 and the controlled terminal of the third switching tube Q3; the resistor R24 is arranged in series between the controlled end and the input end of the third switching tube Q3; the resistor R27 is serially connected between the output end of the PFC driving circuit 20 and the controlled end of the fourth switching tube Q4; the resistor R28 is serially connected between the controlled end and the input end of the fourth switch tube Q4. The resistors R25 and R27 are current limiting resistors, and the resistors R26 and R28 are bias resistors.
The PFC switch circuit 30 further includes a third diode D3 and a fourth diode D4, an anode of the third diode D3 is connected to the first conductive terminal of the fourth switch Q4, and a cathode of the third diode D3 is connected to the reactor L1; an anode of the fourth diode D4 is connected to the second conductive terminal of the third switching tube Q3, and a cathode of the fourth diode D4 is connected to a live line terminal L of an ac power supply. The third diode D3 is connected in anti-parallel with the third switch tube Q3, and the fourth diode D4 is connected in anti-parallel with the fourth switch tube Q4.
When the third switching tube Q3 and the fourth switching tube Q4 are implemented by using IGBTs, when receiving a PFC control signal output by the main controller MCU, the PFC switching circuit 30 drives and controls the conduction of the IGBTs in the PFC switching circuit 30 in the main loop, that is, the third switching tube Q3 and the fourth switching tube Q4 are driven to be conducted. In a positive half cycle, the voltage of the live wire at the alternating current input end is positive relative to the voltage of the zero line, at the moment, the IGBT corresponding to the fourth switching tube Q4 is in a cut-off state, the fourth diode D4 connected in parallel with the IGBT in an opposite direction is conducted, and the path of the main loop current is the live wire at the alternating current input end, namely the reactor L1- (FUSE FUSE1) -the third switching tube Q3-the fourth diode D4-the live wire at the alternating current input end; in a negative half cycle, the voltage of the zero line of the alternating current input end is positive relative to the voltage of the live line, at the moment, the IGBT corresponding to the third switching tube Q3 is in a cut-off state, and the path of conducting the main loop current by the third diode D3 in reverse parallel connection with the third switching tube is the zero line of the alternating current input end, the fourth switching tube Q4, the third diode D3, the reactor L1- (FUSE FUSE1) and the live line of the alternating current input end. By adjusting the pulse width, pulse frequency and the like of the third switching tube Q3 and the fourth switching tube Q4 output by the PFC driving circuit 20, the on-time, on-frequency and the like of the third switching tube Q3 and the fourth switching tube Q4 are further controlled, and power factor correction of the accessed alternating current power supply is realized.
Referring to fig. 2 to 4, in an embodiment, the PFC circuit further includes a tank filter circuit 40, and an input terminal of the tank filter circuit 40 is connected to an output terminal of the rectifier circuit 10.
In this embodiment, the energy storage filter circuit 40 is configured to store the output electric energy and filter the output voltage to stabilize the output voltage. Energy storage filter circuit 40 can adopt electric capacity (C1, C2) to realize, specifically can adopt two electric capacities that set up in series to realize, when adopting two electric capacities (C1, C2) to realize, two electric capacities (C1, C2) set up in series between two output of rectifier circuit 10, and the zero line of AC input end is connected with two filter capacitor's common terminal to realize voltage doubling rectification with rectifier circuit 10. I.e. the voltage value at the output of the rectifier circuit 10 is twice as large as at the input of the rectifier circuit 10.
The invention also provides an air conditioner which comprises the PFC circuit. The detailed structure of the PFC circuit can refer to the above embodiments, and is not described herein again; it can be understood that, because the air conditioner of the present invention uses the PFC circuit, the embodiment of the air conditioner of the present invention includes all technical solutions of all embodiments of the PFC circuit, and the achieved technical effects are also completely the same, and are not described herein again.
The above description is only an alternative embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (9)

1. A PFC circuit, comprising:
one end of the reactor is connected with a live wire end of an alternating current power supply;
the input end of the rectifying circuit is connected with the other end of the reactor;
the PFC driving circuit outputs a corresponding PFC driving signal according to the received PFC control signal;
the controlled end of the PFC switch circuit is connected with the output end of the PFC driving circuit, and the first input/output end of the PFC switch circuit is connected with the other end of the reactor; a second input/output end of the PFC switch circuit is connected with a zero line end of the alternating current power supply; the PFC switch circuit is used for outputting the power supply accessed by the first input/output end to the second input/output end according to the PFC driving signal, or outputting the power supply accessed by the second input/output end to the first input/output end;
the PFC driving circuit comprises a first driving switch, a first resistor, a second resistor and a signal isolation device, wherein a first end of the first resistor is a controlled end of the PFC driving circuit, and a second end of the first resistor is connected with the controlled end of the first driving switch and a first end of the second resistor; the input end of the first driving switch and the second end of the second resistor are connected with a first direct current power supply, the output end of the first driving switch is connected with the input end of the signal isolation device, and the output end of the signal isolation device is the output end of the PFC driving circuit;
the rectifying circuit comprises four diodes, wherein two of the diodes are connected in series and then connected in parallel with the other two diodes which are connected in series; and the other end of the reactor is connected to the common end of the two groups of diodes which are arranged in series.
2. The PFC circuit of claim 1, wherein the PFC switch circuit comprises a first switch tube and a first diode, the controlled terminal of the first switch tube is the controlled terminal of the PFC switch circuit, the input terminal of the first switch tube is the first input/output terminal of the PFC switch circuit, the output terminal of the first switch tube is connected to the anode of the first diode, and the cathode of the first diode is the second input/output terminal of the PFC switch circuit.
3. The PFC circuit of claim 2, wherein the first switching tube is a MOS tube or an IGBT.
4. The PFC circuit of claim 1, wherein the PFC switching circuit comprises a second switching tube and a second diode, the controlled terminal of the second switching tube is the controlled terminal of the PFC switching circuit, the anode of the second diode is the first input/output terminal of the PFC switching circuit, and the cathode of the second diode is connected with the input terminal of the second switching tube; the output end of the second switch tube is a second input/output end of the PFC switch circuit.
5. The PFC circuit of claim 4, wherein the second switching tube is a MOS tube or an IGBT.
6. The PFC circuit of claim 1, wherein the PFC switch circuit comprises a third switch tube and a fourth switch tube, the controlled end of the third switch tube and the controlled end of the fourth switch tube are connected with the output end of the PFC driving circuit, the first conductive end of the third switch tube is a first input/output end of the PFC switch circuit, the second conductive end of the third switch tube is connected with the first conductive end of the fourth switch tube, and the second conductive end of the fourth switch tube is a second input/output end of the PFC switch circuit.
7. The PFC circuit of claim 6, further comprising a third diode and a fourth diode, wherein an anode of the third diode is connected to the first conductive terminal of the fourth switching tube, and a cathode of the third diode is connected to the reactor; and the anode of the fourth diode is connected with the second conductive end of the third switching tube, and the cathode of the fourth diode is connected with the live wire end of the alternating current power supply.
8. The PFC circuit of any of claims 1 to 7, further comprising a tank filter circuit having an input connected to an output of the rectifier circuit.
9. An air conditioner characterized by comprising the PFC circuit according to any one of claims 1 to 8.
CN201910622849.5A 2019-07-09 2019-07-09 PFC circuit and air conditioner Active CN110311547B (en)

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