CN107086770B - PFC circuit and variable frequency air conditioner - Google Patents

Abstract

The invention provides a PFC circuit and a variable frequency air conditioner.A rectifier module is formed by connecting two branches in parallel, wherein the branches comprise diodes and IGBT tubes with freewheeling diodes, the IGBT tubes are connected in series, the rectifier module is connected with the input end of an alternating current power supply, an electric reactor and the rectifier module are connected in series in an alternating current power supply loop, a first capacitor and a second capacitor are connected in series and then connected in parallel at the output end of the rectifier module, one end of a switch module is connected with the alternating current power supply loop, and the other end of the switch module is connected with a common contact of the first capacitor and the second capacitor. When the PFC circuit works, a current loop of the PFC circuit only passes through two diodes including the diode and the freewheeling diode of the IGBT at most, and compared with the prior art that the current loop needs to pass through each diode of two rectifier bridge stacks, the working quantity of the diodes is greatly reduced, so that the heating loss of the whole PFC circuit is reduced, and the energy waste is reduced.

Description

PFC circuit and variable frequency air conditioner

Technical Field

The invention relates to the field of PFC control, in particular to a PFC circuit and a variable frequency air conditioner.

Background

The conventional PFC (Power Factor Correction) circuit for driving a variable frequency compressor or a direct current motor under low voltage such as 100VAC (variable frequency Power supply) Power supply voltage generally adopts voltage-multiplying rectification and then outputs Power supply, the PFC circuit of the conventional voltage-multiplying rectification scheme comprises two rectifier bridge stacks, one of the two rectifier bridge stacks is used for voltage-multiplying rectification, and the other rectifier bridge stack is used for supplying Power to a PFC part after full-wave rectification, in the working process of the whole PFC circuit, each diode of the two bridge stacks has 8 total diodes which need to work, and the two bridge stacks generate heat greatly due to the large working current of the PFC circuit, so that great energy waste is caused. Moreover, the conventional PFC circuit can only operate in a voltage-doubling rectification mode, and has a problem of low conversion efficiency when a load operates in a low-power state, thereby causing energy waste.

Disclosure of Invention

The invention mainly aims to provide a PFC circuit and a variable frequency air conditioner, and aims to solve the problems that a bridge stack of the PFC circuit in the conventional voltage-multiplying rectification mode generates heat greatly and the conversion efficiency is low under low-power load.

In order to achieve the above object, the present invention provides a PFC circuit, which includes a reactor, a rectifier module, a switch module, a first capacitor, a second capacitor, a controller, and a driving module;

the reactor is connected with the input end of the alternating current power supply, and the reactor and the rectifying module are connected in series in an alternating current power supply loop;

the first capacitor and the second capacitor are connected in series and then connected in parallel at the output end of the rectifying module,

the driving module is connected with the output end of the rectifying module in parallel, the rectifying module rectifies input alternating current into direct current to provide a power supply for the driving module to work, the control end of the driving module is connected with the controller, and the controller controls the driving module to drive a load to operate;

the rectification module comprises a first rectification unit and a second rectification unit, the first rectification unit comprises a first diode and a first IGBT (insulated gate bipolar transistor), the second rectification unit comprises a second diode and a second IGBT, the first rectification unit and the second rectification unit are connected in parallel, the first rectification unit and the second rectification unit respectively comprise a branch formed by connecting a diode and an IGBT (insulated gate bipolar transistor) with a freewheeling diode in series, the control ends of the two IGBT of the rectification module are respectively connected with the controller, and the two IGBT of the rectification module are switched on and off under the control of the controller so as to correct the power factor of the direct current voltage and the direct current output by the rectification module;

switch module one end is connected alternating current power supply return circuit, the other end is connected the joint altogether of first electric capacity and second electric capacity, switch module's control end is connected the controller, the controller control switch module's break-make, in order to control by rectifier module with rectifier circuit realization full-bridge rectification and voltage doubling rectification switch are constituteed to first electric capacity and second electric capacity.

The positive electrode of the first diode is connected with the source electrode of the first IGBT tube, the positive electrode of the second diode is connected with the source electrode of the second IGBT tube, the negative electrode of the first diode is connected with the negative electrode of the second diode in parallel to serve as the positive electrode output end of the rectification module, and the drain electrode of the first IGBT tube is connected with the drain electrode of the second IGBT tube in parallel to serve as the negative electrode output end of the rectification module.

The positive electrode of the first diode is connected with the source electrode of the first IGBT tube, the positive electrode of the second diode is connected with the source electrode of the second IGBT tube, the source electrode of the first IGBT tube and the source electrode of the second IGBT tube are connected in parallel and used as the positive electrode output end of the rectification module, and the negative electrode of the first diode and the negative electrode of the second diode are connected in parallel and used as the negative electrode output end of the rectification module.

Preferably, one end of the switch module is connected to a zero line input end of the alternating voltage, and the other end of the switch module is connected to a common junction of the first capacitor and the second capacitor.

Preferably, one end of the switch module is connected to the live wire input end of the alternating voltage, and the other end of the switch module is connected to the common junction point of the first capacitor and the second capacitor.

Preferably, the device also comprises a current detection module,

the current detection module is connected in series with the alternating current loop, and the output end of the current detection module is connected with the controller so as to detect the alternating current value input by the alternating current power supply.

Preferably, the device also comprises a zero-crossing detection module,

the zero-crossing detection module is connected with the input end of the alternating current power supply in parallel, the output end of the zero-crossing detection module is connected with the controller so as to detect a voltage zero-crossing signal of the alternating current power supply, and the controller controls the switching states of the two IGBT tubes of the rectification module to be switched according to the voltage zero-crossing signal.

Preferably, the device also comprises a voltage detection module,

the voltage detection module is connected to the output end of the rectification module in parallel, and the output end of the voltage detection module is connected with the controller to detect the direct-current voltage value output by the rectification module.

Preferably, when the load is a compressor, the controller is further configured to:

judging the current frequency for controlling the operation of the compressor, and controlling the switch module to be conducted by the controller when the operation frequency is greater than a preset value so as to control the rectification module to work in a voltage-multiplying rectification mode; when the operating frequency is smaller than the preset value, the controller controls the second switch module to be switched off so as to control the rectifying module to work in a full-bridge rectifying mode.

In order to achieve the above object, the present invention further provides an inverter air conditioner, which includes the PFC circuit.

The PFC circuit provided by the invention is characterized in that two branches which are formed by connecting a diode and an IGBT (insulated gate bipolar transistor) tube with a freewheeling diode in series are arranged and connected in parallel to form a rectifying module, a reactor is connected with the input end of an alternating current power supply, the reactor and the rectifying module are connected in series in an alternating current power supply loop, a first capacitor and a second capacitor are connected in series and then connected in parallel at the output end of the rectifying module, one end of a switch module is connected with the alternating current power supply loop, and the other end of the switch module is connected with a common junction of the first capacitor and the second capacitor. When the PFC circuit works, a current loop of the PFC circuit only passes through two diodes including the diode and the freewheeling diode of the IGBT at most, and compared with the prior art that the current loop needs to pass through each diode of two rectifier bridge stacks, the working quantity of the diodes is greatly reduced, so that the heating loss of the whole PFC circuit is reduced, and the energy waste is reduced. Moreover, the switch module is used for realizing the switching between the full-bridge rectification mode and the voltage-multiplying rectification mode, so that the PFC circuit can still realize high conversion rate when the load works in a low-power state, and the problem of energy waste caused by low conversion efficiency of the PFC circuit in a single voltage-multiplying rectification mode in the prior art under the low-power condition is solved.

Drawings

Fig. 1 is a schematic circuit diagram of a PFC circuit according to a first embodiment of the present invention;

FIG. 2 is a schematic diagram of a current loop of the reactor during energy storage in the full-bridge rectification mode in the first embodiment;

FIG. 3 is a schematic diagram of a current loop for charging the first capacitor and the second capacitor in the first embodiment when operating in the full-bridge rectification mode;

FIG. 4 is a schematic diagram of another current loop of the first embodiment when reactor L is in energy storage under full-bridge rectification mode;

FIG. 5 is a schematic diagram of another current loop for charging the first capacitor and the second capacitor in the first embodiment when operating in the full-bridge rectification mode;

FIG. 6 is a schematic diagram of a current loop for charging the first capacitor in the voltage-doubling rectifying mode according to the first embodiment;

FIG. 7 is a schematic diagram of a current loop for charging the second capacitor in the voltage-doubler rectification mode according to the first embodiment;

fig. 8 is a schematic circuit diagram of a PFC circuit according to a second embodiment of the present invention;

FIG. 9 is a schematic diagram of a current loop for charging the second capacitor in the voltage-doubling rectifying mode according to the second embodiment;

FIG. 10 is a schematic diagram of a current loop for charging the first capacitor in the voltage-doubler rectification mode according to the second embodiment;

fig. 11 is a schematic circuit diagram of a PFC circuit according to a third embodiment of the present invention;

fig. 12 is a schematic circuit diagram of a PFC circuit according to a fourth embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

Referring to fig. 1, fig. 1 is a structural diagram of a PFC circuit according to a first embodiment of the present invention, and for convenience of description, only the parts related to the embodiment of the present invention are shown, and detailed descriptions are as follows:

the PFC circuit provided by the embodiment of the present invention includes a reactor L, a rectifier module 10, a switch module 20, a first capacitor E1, a second capacitor E2, a controller 30, and a driving module 40;

the reactor L is connected with the input end of the alternating current power supply, and the reactor L and the rectifying module 10 are connected in series in an alternating current power supply loop;

the first capacitor E1 and the second capacitor E2 are connected in series and then connected in parallel to the output end of the rectifier module 10,

the driving module 40 is connected in parallel to the output end of the rectifying module 10, the rectifying module 10 rectifies the input alternating current into direct current to provide a power supply for the operation of the driving module 40, the control end of the driving module 40 is connected with the controller 30, and the controller 30 controls the driving module 40 to drive the load to operate;

the rectifying module 10 includes a first rectifying unit 11 and a second rectifying unit 12, the first rectifying unit 11 includes a first diode D1 and a first IGBT Q1, the second rectifying unit 12 includes a second diode D2 and a second IGBT Q2, the first rectifying unit 11 and the second rectifying unit 12 are connected in parallel, the first rectifying unit 11 and the second rectifying unit 12 respectively include a branch formed by a diode and an IGBT (Insulated Gate Bipolar Transistor) with a freewheeling diode connected in series, control ends of two IGBT of the rectifying module 10 are respectively connected to the controller 30, and the two IGBT of the rectifying module 10 are switched under the control of the controller 30 to perform power factor correction on a direct current voltage and a direct current output by the rectifying module 10;

one end of the switch module 20 is connected with the alternating current power supply loop, the other end of the switch module is connected with the common connection point of the first capacitor E1 and the second capacitor E2, the control end of the switch module 20 is connected with the controller 30, and the controller 30 controls the on-off of the switch module 20 so as to control the rectifier circuit consisting of the rectifier module 10, the first capacitor E1 and the second capacitor E2 to realize the switching of full-bridge rectification and voltage-doubling rectification.

Specifically, the switch module 20 includes a switch K1 and a switch driving unit 1 for driving the switch K1, where the switch K1 is generally a relay, the switch driving unit is a corresponding circuit for driving the relay, and has a driving circuit formed by a triode, a control stage, i.e., a base, of the triode is a control end of the first switch module 20, two switch ends of the relay are two ends of the first switch module 20, and the controller 60, i.e., a control port of the MCU, controls on/off of the switch K1 through the switch driving unit via an output signal. Here, since the relay and the switch driving unit for driving the relay are related to the prior art, detailed circuits thereof are not described in detail.

The first rectifying unit 11 of the rectifying module 10 includes a first diode D1 and a first IGBT tube Q1, and the second rectifying unit 12 includes a second diode D2 and a second IGBT tube Q2;

the positive pole of first diode D1 is connected with the collector of first IGBT pipe Q1, and the positive pole of second diode D2 is connected with the collector of second IGBT pipe Q2, and the positive pole output of rectifier module 10 is connected in parallel as to the negative pole of first diode D1 and the negative pole of second diode D2, and the emitting pole of first IGBT pipe Q1 and the emitting pole of second IGBT pipe Q2 are connected in parallel as the negative pole output of rectifier module 10.

One end of the switch module 20 is connected to the zero line input end of the ac power supply, and the other end is connected to the common node of the first capacitor E1 and the second capacitor E2.

The PFC circuit of this embodiment further includes a zero-crossing detection module 60, the zero-crossing detection module 60 is connected in parallel to the input end of the ac power supply, the output end of the zero-crossing detection module 60 is connected to the controller 30 to detect a voltage zero-crossing signal of the ac power supply, and the controller controls the switching states of the two IGBT tubes of the rectification module 10 according to the voltage zero-crossing signal. The specific circuit of the zero-crossing detection module 60 can refer to the prior art, and is not described in detail here.

The PFC circuit of this embodiment further includes a current detection module 50, the current detection module 50 is connected in series to the ac loop, and in fig. 1, the current detection module 50 is connected in series to a live line end of the ac power source, or certainly, may be connected in series to a zero line end of the ac power source, and an output end of the current detection module 50 is connected to the controller 30 to detect an ac current value input by the ac power source. The current detection module 50 is composed of a current transformer T1 and an additional detection circuit, and the specific circuit of the current detection module 50 may refer to the prior art and is not described herein again.

The PFC circuit of this embodiment further includes a voltage detection module 70, wherein the voltage detection module 70 is connected in parallel to the output end of the rectification module 10, and the output end of the voltage detection module 70 is connected to the controller 30 to detect the dc voltage value output by the rectification module 10. The voltage detection module 70 may be formed by a simple circuit based on a resistor voltage division structure, and the detailed circuit may refer to the prior art and is not described herein again.

The working principle of the PFC circuit shown in this embodiment is as follows: when the switch module 20 is turned off, the rectifier module composed of the rectifier module 10, the first capacitor E1 and the second capacitor E2 operates in a full-bridge rectification mode. As shown in fig. 2, when the controller 30 controls the first IGBT Q1 to be turned on and the second IGBT Q2 to be turned off, at this time, the ac power supply current starts from the live line, i.e., L line, and returns to the zero line of the ac power supply, i.e., N line, through the reactor L, the collector and emitter of the first IGBT Q1, and the anode and cathode of the freewheeling diode D4 of the second IGBT Q2 to form a loop, so as to store energy in the reactor L; as shown in fig. 3, when the controller 30 controls the first IGBT Q1 to turn off, an induced electromotive force is generated in the reactor L, and the direction of the current flowing through the reactor L is the same as that before the first IGBT Q1 turns off, and at this time, the current generated by the induced electromotive force of the reactor L forms a current loop through the first diode D1, the first capacitor E1, the second capacitor E2, and the freewheeling diode D4 of the second IGBT Q2 to charge the first capacitor E1 and the second capacitor E2, thereby realizing power factor correction of the dc voltage and the current output from the rectifier module 10 when the ac power supply current starts from the L line. As shown in fig. 4, when the controller 30 controls the second IGBT Q2 to be turned on and the first IGBT Q1 to be turned off, at this time, the ac power supply current starts from the live line, i.e., the N line, and passes through the collector and emitter of the second IGBT Q2, the anode and cathode of the freewheeling diode D3 of the first IGBT Q1, and the reactor L returns to the zero line of the ac power supply, i.e., the L line, to form a loop, so as to store energy in the reactor L; as shown in fig. 5, when the controller 30 controls the second IGBT Q2 to be turned off, the reactor L generates induced electromotive force, the direction of the current flowing through the reactor L is consistent with the direction before the second IGBT Q2 is turned off, and the current generated by the induced electromotive force of the reactor L at this time flows through the second diode D2, the first capacitor E1, the second capacitor E2, and the freewheeling diode D3 of the first IGBT Q1 to form a current loop to charge the first capacitor E1 and the second capacitor E2, thereby achieving power factor correction of the dc voltage and the current output from the rectifier module 10 when the ac power supply current starts from the N line. In the process that the first capacitor E1 and the second capacitor E2 are charged by the induced electromotive force generated by the reactor L, the first diode D1, the second diode D2, the freewheeling diode D3 of the first IGBT Q1, and the freewheeling diode D4 of the second IGBT Q2 form a full-bridge rectification mode, and therefore, the controller respectively controls the first IGBT Q1 and the second IGBT Q2 to be alternately switched on and off, thereby realizing the power factor correction function in the full-bridge rectification mode.

When the switch module 20 is turned on, the rectifier module composed of the rectifier module 10, the first capacitor E1 and the second capacitor E2 operates in the voltage-doubler rectification mode. When the controller 30 controls the first IGBT tube Q1 to be turned on and the second IGBT tube Q2 to be turned off, a loop of the alternating current power supply current from the L line is the same as that in fig. 2, so that energy storage of the reactor L is realized; as shown in fig. 6, when the controller 30 controls the first IGBT Q1 to be turned off, an induced electromotive force is generated in the reactor L, and the direction of the current flowing through the reactor L is the same as that before the first IGBT Q1 is turned off, and at this time, the current generated by the induced electromotive force of the reactor L is looped through the first diode D1, the first capacitor E1, and the switch K1 to charge the first capacitor E1, thereby realizing power factor correction of the dc voltage and the current output from the rectifier module 10 when the ac power supply current starts from the L line. When the controller 30 controls the second IGBT tube Q2 to be turned on and the first IGBT tube Q1 to be turned off, a loop of the alternating current power supply current from the N line is the same as that in fig. 4, so that energy storage of the reactor L is realized; as shown in fig. 7, when the controller 30 controls the second IGBT Q2 to turn off, the reactor L generates induced electromotive force, and the direction of the current flowing through the reactor L is the same as that before the second IGBT Q2 is turned off, and at this time, the current generated by the induced electromotive force of the reactor L is in a current loop through the switch K1, the second capacitor E2, and the freewheeling diode D3 of the first IGBT Q1 to charge the second capacitor E2, thereby realizing power factor correction of the dc voltage and the current output from the rectifier module 10 when the ac power supply current starts from the N line. The induced electromotive forces with different polarities generated by the reactor L respectively charge the first capacitor E1 and the second capacitor E2, so that the voltages at the two ends of the first capacitor E1 and the second capacitor E2 are one time of the voltage on a single capacitor, and a voltage-doubling rectification mode is realized. Therefore, the controller respectively controls the first IGBT tube Q1 and the second IGBT tube Q2 to be switched on and off alternately, and the power factor correction function in the voltage-multiplying rectification mode is achieved.

In the PFC circuit shown in this embodiment, the load driven by the driving Module 40 includes a compressor or a motor, where the compressor or the motor is a permanent magnet synchronous motor, and the driving Module includes a circuit composed of an IPM Module (Intelligent Power Module), and the driving of the compressor or the motor is realized by inverting a direct current loaded on the IPM Module into an alternating current under the control of the controller 30. When the PFC circuit of this embodiment is in operation, because the input of the PFC circuit is an alternating current, it is necessary to ensure that a current is maintained when the first IGBT Q1 or the second IGBT Q2 operates to store energy in the reactor L, so that the controller needs to detect a zero-crossing signal of the alternating current through the zero detection module 60, and only after the zero-crossing, the first IGBT Q1 or the second IGBT is controlled to be turned on to ensure that the energy storage in the reactor L can be realized through a continuous current. In addition, during the working process of the PFC circuit, the controller 30 needs to obtain the current working current of the circuit through the current detection module 50, and if the working current of the load is found to be too high, which causes the too high working current of the PFC circuit, the controller 30 controls the two IGBT tubes to be turned off to turn off the PFC circuit to protect the whole PFC circuit. In the process of the PFC circuit of this embodiment, the controller 30 further needs to detect the dc voltage output by the rectifier module, i.e. the dc bus voltage, in real time through the voltage detection module 70, and when the dc bus voltage value is higher, the pulse width value of the first IGBT tube Q1 or the second IGBT tube may be adjusted to reduce the output dc bus voltage value, thereby achieving the stability of the dc bus voltage value.

As can be known from the above working process, when the PFC circuit of this embodiment operates in the full-bridge rectification mode, when the reactor L stores energy, the current loop only passes through the freewheeling diode of one of the IGBT tubes, and when the reactor L generates induced electromotive force to charge the first capacitor E1 and the second capacitor E2, the current loop only passes through one of the diodes and the freewheeling diode of one of the IGBT tubes; when the reactor L is operated in a voltage-multiplying rectification mode, when the reactor L stores energy, the current loop only passes through the freewheeling diode of one of the IGBT tubes, and when the reactor L generates induced electromotive force to charge the first capacitor E1 and the second capacitor E2, the current loop only passes through one of the diodes or the freewheeling diode of one of the IGBT tubes. Compared with the prior art that when the PFC circuit sampling two rectifier bridge stacks works, each diode of each bridge stack works, the PFC circuit of the embodiment of the invention greatly reduces the working number of the diodes when in work, thereby reducing the heating loss of the whole PFC circuit and reducing the energy waste.

When the rectifier module shown in this embodiment operates in the voltage-doubling rectification mode, the rectifier module is suitable for boosting the output dc voltage through voltage-doubling rectification when the input ac voltage is low, for example, the input ac voltage is 100V, taking a load as an example, and when the compressor operates in a high-power environment, because a relatively high voltage is required to drive the compressor to normally operate, the output dc bus voltage value needs to be boosted through voltage-doubling rectification. And under the low power load, if the compressor works in the low frequency state, for example, when the working frequency of the compressor is less than the preset value 20Hz, the working current of the circuit is low at this time, because the conversion efficiency of the PFC circuit in the voltage-doubling rectification mode is low at this time, and the compressor can not need a relatively high working voltage value at this time, the controller 30 controls the switch module 20 to be switched off, so that the rectification module works in the full-bridge rectification mode, because the conversion efficiency of the PFC circuit in the full-bridge rectification mode is improved, the efficiency of the whole PFC circuit can be improved at this time, and the energy waste can be reduced. Specifically, the controller 30 needs to obtain the current frequency of the compressor, and if the frequency of the compressor is smaller than the preset value, that is, the current working current of the compressor is low, the switch module 20 is controlled to be turned off, so that the rectifier module works in a full-bridge rectification mode to improve the conversion efficiency of the PFC circuit; if the frequency of the compressor is greater than the preset value, that is, the current working current of the compressor is increased, the switch module 20 is controlled to be switched on to enable the rectifier module to work in the voltage-doubling rectifier mode to increase the working voltage of the load so as to maintain the normal work of the load.

According to the PFC circuit provided by the embodiment of the invention, two branches which are formed by connecting diodes and IGBT tubes with freewheeling diodes in series are arranged and connected in parallel to form a rectifying module 10, a reactor L is connected with the input end of an alternating current power supply, the reactor L and the rectifying module 10 are connected in series in an alternating current power supply loop, a first capacitor E1 and a second capacitor E2 are connected in series and then connected in parallel at the output end of the rectifying module 10, one end of a switch module is connected with the alternating current power supply loop, and the other end of the switch module is connected with a common junction of the first capacitor E1 and the second capacitor E2. When the PFC circuit works, a current loop of the PFC circuit only passes through two diodes including the diode and the freewheeling diode of the IGBT at most, and compared with the prior art that the current loop needs to pass through each diode of two rectifier bridge stacks, the working quantity of the diodes is greatly reduced, so that the heating loss of the whole PFC circuit is reduced, and the energy waste is reduced. Moreover, the switch module is used for realizing the switching between the full-bridge rectification mode and the voltage-multiplying rectification mode, so that the PFC circuit can still realize high conversion rate when the load works in a low-power state, and the problem of energy waste caused by low conversion efficiency of the PFC circuit in a single voltage-multiplying rectification mode in the prior art under the low-power condition is solved.

Further, based on the first embodiment of the PFC circuit of the present invention, as shown in fig. 8, a second embodiment of the PFC circuit of the present invention is different from the first embodiment in a circuit connection manner of the switch module 20.

One end of the switch module 20 is connected to the live wire input end of the ac power supply, and the other end is connected to the common node of the first capacitor E1 and the second capacitor E2.

In the present embodiment, the switch module 20 is instead connected to the line terminal, i.e. the L terminal, of the near ac power source, specifically, connected in parallel between the reactor L and an ac input terminal of the rectifier module 20.

The operation principle of the PFC circuit of this embodiment is the same as that of the first embodiment when the switching module is turned off in the full-bridge rectification mode. When the switch module closed loop is in the voltage-multiplying rectification mode, when the first IGBT Q1 or the second IGBT Q2 is turned on so that the reactor L is in the energy storage state, the operating principle is the same as that of the first embodiment, except that when the first IGBT Q1 or the second IGBT Q2 is turned off so that the current loop formed by the induced electromotive force generated by the reactor L is different. As shown in fig. 9, when the first IGBT Q1 is turned off from on, an induced electromotive force is generated in the reactor L, and the direction of the current flowing through the reactor L is the same as that before the first IGBT Q1 is turned off, and at this time, the current generated by the induced electromotive force of the reactor L is looped through the switch K1, the second capacitor E2, and the freewheeling diode D4 of the second IGBT Q2 to charge the second capacitor E2, thereby realizing power factor correction of the dc voltage and the current output from the rectifier module 10 when the ac power supply current starts from the L line; as shown in fig. 10, when the second IGBT tube Q2 is turned off from on, an induced electromotive force is generated in the reactor L, and the direction of the current flowing through the reactor L is the same as that before the second IGBT tube Q2 is turned off, and the current generated by the induced electromotive force of the reactor L flows through the second diode D2, the first capacitor E1, and the switch K1 to form a loop to charge the first capacitor E1, thereby realizing power factor correction of the dc voltage and the current output from the rectifier module 10 when the ac power supply current starts from the N-line direction. The charging process only needs one diode, and compared with the prior art, the charging process needs to greatly reduce each diode passing through two rectifier bridge stacks, so that the heating loss of the whole PFC circuit is reduced.

Further, based on the first embodiment of the PFC circuit of the present invention, a PFC circuit according to a third embodiment of the present invention is shown in fig. 11, and is different from the first embodiment in a circuit structure of the rectifying module 10.

The positive pole of first diode is connected the collector of first IGBT pipe Q1, and the positive pole of second diode is connected the collector of second IGBT pipe Q2, and the positive pole output as rectifier module is parallelly connected with the negative pole of second diode to the first diode negative pole, and the emitting pole of first IGBT pipe Q1 and the emitting pole of second IGBT pipe Q2 are parallelly connected as rectifier module's negative pole output. That is, the connection positions of the diodes and the IGBT tubes in the first rectifying unit 11 and the second rectifying unit 12 are exchanged with respect to the first embodiment.

The PFC circuit of this embodiment is similar to the first embodiment in that when the first IGBT Q1 or the second IGBT Q2 of the PFC circuit is turned on, its current respectively passes through the freewheeling diode of one of the IGBT and the collector and emitter of the other IGBT in the current loop to store energy in the reactor L; when the first IGBT Q1 or the second IGBT Q2 is turned on and turned off, the induced electromotive force generated by the reactor L charges the first capacitor E1 and the second capacitor E2 in a full-bridge rectification and voltage-doubling rectification mode in which the switch module 20 is turned off and closed loop is formed, and the charging circuit thereof is the same as the diode of the first embodiment only through one diode and one freewheeling diode of the IGBT at most, so that the working number of the diode is greatly reduced as compared with the prior art, the heat loss of the entire PFC circuit is reduced, and the energy waste is reduced.

Further, based on the third embodiment of the PFC circuit of the present invention, as shown in fig. 12, the PFC circuit of the fourth embodiment of the present invention is different from the third embodiment in the circuit connection manner of the switch module 20. The connection mode of the switch module 20 is the same as the circuit connection mode of the switch module 20 in the second embodiment.

The principle of the PFC circuit of this embodiment is similar to that of the third embodiment, and in the working process of the PFC circuit, the number of diodes in the current loop is at most only one diode and one freewheeling diode of the IGBT, which is the same as that of the first embodiment, so that the number of diodes is greatly reduced compared with the prior art, the heat loss of the entire PFC circuit is reduced, and the energy waste is reduced.

The present invention further provides an inverter air conditioner, which comprises an indoor unit and an outdoor unit, wherein the outdoor unit comprises an inverter compressor, and the outdoor unit control circuit comprises the PFC circuit.

In the description herein, references to the description of the terms "first embodiment," "second embodiment," "example," etc., mean that a particular method, apparatus, or feature described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, methods, apparatuses, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims (10)

1. A power factor correction circuit is characterized by comprising a reactor, a rectifying module, a switch module, a first capacitor, a second capacitor, a controller and a driving module;

the reactor is connected with the input end of the alternating current power supply, and the reactor and the rectifying module are connected in series in an alternating current power supply loop;

the first capacitor and the second capacitor are connected in series and then connected in parallel at the output end of the rectifying module,

the driving module is connected with the output end of the rectifying module in parallel, the rectifying module rectifies input alternating current into direct current to provide a power supply for the driving module to work, the control end of the driving module is connected with the controller, and the controller controls the driving module to drive a load to operate;

the rectification module comprises a first rectification unit and a second rectification unit, the first rectification unit comprises a first diode and a first IGBT (insulated gate bipolar transistor), the second rectification unit comprises a second diode and a second IGBT, the first rectification unit and the second rectification unit are connected in parallel, the first rectification unit and the second rectification unit respectively comprise a branch formed by connecting a diode and an IGBT (insulated gate bipolar transistor) with a freewheeling diode in series, the control ends of the two IGBT of the rectification module are respectively connected with the controller, and the two IGBT of the rectification module are switched on and off under the control of the controller so as to correct the power factor of the direct current voltage and the direct current output by the rectification module;

switch module one end is connected alternating current power supply return circuit, the other end is connected the joint altogether of first electric capacity and second electric capacity, switch module's control end is connected the controller, the controller control switch module's break-make, in order to control by rectifier module with rectifier circuit realization full-bridge rectification and voltage doubling rectification switch are constituteed to first electric capacity and second electric capacity.

2. The power factor correction circuit of claim 1,

the positive electrode of the first diode is connected with the source electrode of the first IGBT tube, the positive electrode of the second diode is connected with the source electrode of the second IGBT tube, the negative electrode of the first diode is connected with the negative electrode of the second diode in parallel to serve as the positive electrode output end of the rectification module, and the drain electrode of the first IGBT tube is connected with the drain electrode of the second IGBT tube in parallel to serve as the negative electrode output end of the rectification module.

3. The power factor correction circuit of claim 1,

the positive electrode of the first diode is connected with the source electrode of the first IGBT tube, the positive electrode of the second diode is connected with the source electrode of the second IGBT tube, the source electrode of the first IGBT tube and the source electrode of the second IGBT tube are connected in parallel and used as the positive electrode output end of the rectification module, and the negative electrode of the first diode and the negative electrode of the second diode are connected in parallel and used as the negative electrode output end of the rectification module.

4. The power factor correction circuit of claim 1,

one end of the switch module is connected with the zero line input end of the alternating voltage, and the other end of the switch module is connected with the common junction of the first capacitor and the second capacitor.

5. The power factor correction circuit of claim 1,

one end of the switch module is connected with the live wire input end of the alternating voltage, and the other end of the switch module is connected with the common junction point of the first capacitor and the second capacitor.

6. The power factor correction circuit of claim 1, further comprising a current detection module,

the current detection module is connected in series with the alternating current power supply loop, and the output end of the current detection module is connected with the controller so as to detect the alternating current value input by the alternating current power supply.

7. The power factor correction circuit of claim 1, further comprising a zero crossing detection module,

the zero-crossing detection module is connected with the input end of the alternating current power supply in parallel, the output end of the zero-crossing detection module is connected with the controller to detect a voltage zero-crossing signal of the alternating current power supply, and the controller controls the switching states of two IGBT tubes of the rectification module to be switched according to the voltage zero-crossing signal.

8. The power factor correction circuit of claim 1, further comprising a voltage detection module,

the voltage detection module is connected in parallel with the output end of the rectification module, and the output end of the voltage detection module is connected with the controller so as to detect the direct-current voltage value output by the rectification module.

9. The power factor correction circuit of claim 1,

when the load is a compressor, the controller is further configured to:

judging the current frequency for controlling the operation of the compressor, and controlling the switch module to be conducted by the controller when the operation frequency is greater than a preset value so as to control the rectification module to work in a voltage-multiplying rectification mode; when the operating frequency is smaller than the preset value, the controller controls the second switch module to be switched off so as to control the rectifying module to work in a full-bridge rectifying mode.

10. An inverter air conditioner comprising the power factor correction circuit as claimed in any one of claims 1 to 9.

Images