阅读说明：本技术 功率因数校正电路、外机控制器及空调器 (Power factor correction circuit, outer unit controller and air conditioner ) 是由 刘军 游剑波 陈志强 周振威 于 2020-12-30 设计创作，主要内容包括：本发明提供了一种功率因数校正电路、外机控制器及空调器,该电路包括：整流电路及功率因数校正开关电路；整流电路包括整流桥,整流桥的输入端连接交流工作电压,整流桥的直流输出正极连接功率因数校正开关电路；功率因数校正开关电路包括碳化硅金氧半场效晶体管、串联的电感及碳化硅肖特基二极管；碳化硅金氧半场效晶体管的漏极连接至电感与碳化硅肖特基二极管之间,源极与整流桥的直流输出负极连接,栅极与栅极驱动器集成电路连接。本发明采用SiC器件代替原有电路中的Si器件,可以提高开关频率以及间接减少其他器件例如电感、散热器的体积,降低整个控制器的体积,使得控制器效率提高且体积减小。(The invention provides a power factor correction circuit, an external unit controller and an air conditioner, wherein the circuit comprises: a rectification circuit and a power factor correction switching circuit; the rectifying circuit comprises a rectifying bridge, the input end of the rectifying bridge is connected with alternating-current working voltage, and the direct-current output positive electrode of the rectifying bridge is connected with the power factor correction switching circuit; the power factor correction switch circuit comprises a silicon carbide metal-oxide-semiconductor field effect transistor, an inductor and a silicon carbide Schottky diode which are connected in series; the drain electrode of the silicon carbide gold oxygen semi-field effect transistor is connected between the inductor and the silicon carbide Schottky diode, the source electrode of the silicon carbide gold oxygen semi-field effect transistor is connected with the direct current output negative electrode of the rectifier bridge, and the grid electrode of the silicon carbide gold oxygen semi-field effect transistor is connected with the grid driver integrated circuit. The invention adopts SiC device to replace Si device in original circuit, which can improve switch frequency and indirectly reduce the volume of other devices such as inductance and radiator, and reduce the volume of the whole controller, so as to improve the efficiency and reduce the volume of the controller.)

1. A power factor correction circuit is applied to an air conditioner and comprises the following components: a rectification circuit and a power factor correction switching circuit;

the rectifying circuit comprises a rectifying bridge, the input end of the rectifying bridge is connected with alternating-current working voltage, and the direct-current output positive electrode of the rectifying bridge is connected with the power factor correction switching circuit;

the power factor correction switch circuit comprises a silicon carbide metal oxide semiconductor field effect transistor, an inductor and a silicon carbide Schottky diode which are connected in series;

the drain electrode of the silicon carbide gold oxygen semi-field effect transistor is connected between the inductor and the silicon carbide Schottky diode, the source electrode of the silicon carbide gold oxygen semi-field effect transistor is connected with the direct current output negative electrode of the rectifier bridge, and the grid electrode of the silicon carbide gold oxygen semi-field effect transistor is connected with the grid driver integrated circuit.

2. The power factor correction circuit of claim 1, further comprising a protection circuit;

the protection circuit comprises a first resistor and a one-way conduction element which are connected in series;

the first resistor and the one-way conduction element are connected in series and then connected in parallel with the inductor and the silicon carbide Schottky diode which are connected in series;

the conduction direction of the one-way conduction element is the same as that of the silicon carbide Schottky diode.

3. The power factor of claim 2Correction circuit characterized in that the maximum current in the power factor correction circuit is I_maxA first total resistance R of the inductor and the SiC Schottky diode_{General 1}A second total resistance R of the resistor and the unidirectional conducting element_{General 2}Peak current maximum value I of the silicon carbide Schottky diode_SBD，R_{General 1}And R_{General 2}The following conditions are satisfied:

I_maxR_{general 2}/(R_{General 1}+R_{General 2})≤I_SBD。

4. The power factor correction circuit of claim 2, wherein a maximum current in the power factor correction circuit is I_maxA first total resistance R of the inductor and the SiC Schottky diode_{General 1}A second total resistance R of the resistor and the unidirectional conducting element_{General 2}Peak current maximum value I of the silicon carbide Schottky diode_{Protection of}，R_{General 1}And R_{General 2}The following conditions are satisfied:

I_maxR_{general 1}/(R_{General 1}+R_{General 2})≤I_{Protection of}。

5. The PFC circuit of any one of claims 1-4, wherein the one-way conduction element is a rectifier diode or a one-way thyristor.

6. The power factor correction circuit of any of claims 1-4, further comprising a filter capacitor;

the filter capacitor is connected between the direct current output positive electrode and the direct current output negative electrode.

7. The power factor correction circuit of any of claims 1-4, further comprising an electrolytic capacitor;

the electrolytic capacitor is connected between the cathode of the silicon carbide Schottky diode and the ground.

8. The power factor correction circuit of any of claims 1-4, further comprising a second resistor and a protection capacitor;

the second resistor and the protective capacitor are connected in series and then connected in parallel with the silicon carbide Schottky diode.

9. An outdoor unit controller, for use in an air conditioner, comprising the power factor correction circuit as claimed in any one of claims 1 to 8.

10. An air conditioner characterized by comprising the outdoor unit controller according to claim 9.

Technical Field

The invention relates to the technical field of air conditioners, in particular to a power factor correction circuit, an external unit controller and an air conditioner.

Background

In the current air conditioner, a Power Factor Correction (PFC) circuit on an external unit controller uses an Insulated Gate Bipolar Transistor (IGBT) and a silicon Fast Recovery Diode (FRD) made of a silicon Si material.

The conventional PFC circuit based on the Si device has low switching frequency, large inductance and large volume of PFC inductor, so that the controller has large volume and low efficiency.

Disclosure of Invention

The invention solves the problems that the switching frequency of the conventional PFC circuit based on the Si device is low, and the inductance and the volume of the PFC inductor are large, so that the size and the efficiency of a controller are low.

In order to solve the above problems, the present invention provides a power factor correction circuit applied to an air conditioner, comprising: a rectification circuit and a power factor correction switching circuit; the rectifying circuit comprises a rectifying bridge, the input end of the rectifying bridge is connected with alternating-current working voltage, and the direct-current output positive electrode of the rectifying bridge is connected with the power factor correction switching circuit; the power factor correction switch circuit comprises a silicon carbide metal oxide semiconductor field effect transistor, an inductor and a silicon carbide Schottky diode which are connected in series; the drain electrode of the silicon carbide gold oxygen semi-field effect transistor is connected between the inductor and the silicon carbide Schottky diode, the source electrode of the silicon carbide gold oxygen semi-field effect transistor is connected with the direct current output negative electrode of the rectifier bridge, and the grid electrode of the silicon carbide gold oxygen semi-field effect transistor is connected with the grid driver integrated circuit.

The invention adopts SiC device to replace Si device in original circuit, which can improve switch frequency and indirectly reduce the volume of other devices such as inductance and radiator, and reduce the volume of the whole controller, so as to improve the efficiency and reduce the volume of the controller.

Optionally, a protection circuit is further included; the protection circuit comprises a first resistor and a one-way conduction element which are connected in series; the first resistor and the one-way conduction element are connected in series and then connected in parallel with the inductor and the silicon carbide Schottky diode which are connected in series; the conduction direction of the one-way conduction element is the same as that of the silicon carbide Schottky diode.

The invention provides a protection circuit for power grid fluctuation, can avoid damage of SiC SBD and other controller devices, and improves reliability.

Optionally, the maximum current in the power factor correction circuit is I_maxA first total resistance R of the inductor and the SiC Schottky diode_{General 1}A second total resistance R of the resistor and the unidirectional conducting element_{General 2}Peak current maximum value I of the silicon carbide Schottky diode_SBD，R_{General 1}And R_{General 2}The following conditions are satisfied:

I_maxR_{general 2}/(R_{General 1}+R_{General 2})≤I_SBD。

The invention limits the relation between the resistor and the one-way conduction element in the protection circuit and the resistor between the SiC SBD and the inductor in the power factor correction switch circuit, and can ensure that the devices are not damaged by surge current.

Optionally, the maximum current in the power factor correction circuit is I_maxA first total resistance R of the inductor and the SiC Schottky diode_{General 1}A second total resistance R of the resistor and the unidirectional conducting element_{General 2}Peak current maximum value I of the silicon carbide Schottky diode_{Protection of}，R_{General 1}And R_{General 2}The following conditions are satisfied:

I_maxR_{general 1}/(R_{General 1}+R_{General 2})≤I_{Protection of}。

The invention limits the relation between the resistor and the one-way conduction element in the protection circuit and the resistor between the SiC SBD and the inductor in the power factor correction switch circuit, and can ensure that the devices are not damaged by surge current.

Optionally, the unidirectional conducting element is a rectifier diode or a unidirectional thyristor.

The invention provides a specific type of the one-way conduction element, which can play a role in protecting controller devices such as SiC SBDs and the like.

Optionally, a filter capacitor is further included; the filter capacitor is connected between the direct current output positive electrode and the direct current output negative electrode.

The circuit provided by the invention comprises a filter capacitor of a rectifying filter circuit, and is used for high-frequency filtering and realizing the function of controlling the input current waveform of a PFC circuit.

Optionally, an electrolytic capacitor is also included; the electrolytic capacitor is connected between the cathode of the silicon carbide Schottky diode and the ground.

The circuit provided by the invention comprises an electrolytic capacitor and is used for realizing the function of controlling the input current waveform of the PFC circuit.

Optionally, the device further comprises a second resistor and a protection capacitor; the second resistor and the protective capacitor are connected in series and then connected in parallel with the silicon carbide Schottky diode.

The circuit provided by the invention also comprises devices such as a resistor, a capacitor and the like, and is used for realizing the function of controlling the input current waveform of the PFC circuit.

The invention provides an external unit controller, which is applied to an air conditioner and comprises the power factor correction circuit.

The invention provides an air conditioner, which comprises the outdoor unit controller.

The external machine controller and the air conditioner can achieve the same technical effect as the power factor correction circuit.

Drawings

Fig. 1 is a schematic structural diagram of a power factor correction circuit according to an embodiment of the present invention.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

In this embodiment, SiC devices are used instead of Si devices, including: silicon carbide SiC Metal-Oxide-Semiconductor Field-Effect transistors (MOSFETs) are used instead of Si IGBT devices, and SiC Schottky diodes (SBDs) are used instead of Si FRDs. The SiC MOSFET has the characteristics of high voltage resistance, low impedance, high frequency, low loss, high temperature resistance and the like; the SiC SBD has very short reverse recovery time, very small reverse current, and also has the characteristics of high voltage resistance, low impedance, high frequency, low loss, high temperature resistance and the like.

Fig. 1 is a schematic diagram of a power factor correction circuit according to the present invention, which is applied to an air conditioner and shows a rectifier circuit 100 and a power factor correction switching circuit 200.

The rectifier circuit 100 includes a rectifier bridge BG, input terminals 2 and 3 of which are connected to an ac operating voltage, and a dc output anode 1 of which is connected to a power factor correction switching circuit 200.

The PFC switch circuit 200 includes a SiC MOSFET, a series inductor L₁And a silicon carbide schottky diode SiC SBD.

Further, the drain D of the SiC MOSFET is connected to the inductor L₁And a source S is connected with a direct current output cathode 2 of the rectifier bridge and a grid G is connected with a grid driver integrated circuit IC between the silicon carbide Schottky diode SiC SBD.

According to the power factor correction circuit provided by the embodiment, the SiC device is adopted to replace a Si device in an original circuit, so that the switching frequency can be improved, the volumes of other devices such as an inductor and a radiator can be indirectly reduced, the volume of the whole controller is reduced, and the efficiency of the controller is improved and the volume is reduced.

It is considered that although SiC SBD has a very significant advantage compared to Si FRD, SiC SBD has poor surge current resistance. The maximum surge current resistance value of the SiC SBD is much lower than that of the Si FRD of silicon, so that when the voltage drops due to power grid fluctuation, a large surge current is generated, which impacts devices on PFC circuits such as the SiC SBD and a rectifier circuit, and damages the SiC SBD or reduces the service life of the devices.

The problem that the voltage drops due to the fluctuation of the power grid, and then the device on the controller is damaged or the service life is influenced is often ignored. The phenomenon often appears in daily life, and the illuminating lamp becomes dark suddenly and then returns to normal; this is also the case in many industrial parks, where the local grid quality is poor, because there are many small companies in the industrial park, which have many power devices of different sizes, starting them individually without interruption, and the large and small power device starts causing fluctuations in the grid voltage, and voltage drops caused by the grid voltage fluctuations, which actually cause surge currents, impact is caused to the devices on the air conditioner controller, the service life of the devices is influenced or the devices are directly damaged, has great influence on the quality of a local power grid, not only has large harmonic content and unstable voltage, that is to say, the actual use environment of the air conditioner is worse, therefore, for frequent fluctuations of the grid, when SiC SBD devices are used instead of Si FRDs, because the maximum surge current resistance value of the SiC SBD is much lower than that of the Si FRD, a protection circuit for resisting surge current must be designed, so that the damage of devices is avoided, and the reliability is improved.

For the above reasons, the power factor correction circuit of the present embodiment also designs a protection circuit for SiC SBD. As shown in FIG. 1, the protection circuit 300 includes a first resistor R connected in series₁And a unidirectional conducting element D₁。

A first resistor R₁And a unidirectional conducting element D₁Inductor L connected in series₁Is connected with a silicon carbide Schottky diode SiC SBD in parallel; one-way conduction element D₁The conduction direction of (b) is the same as the conduction direction of the silicon carbide schottky diode SiC SBD. Optionally, the one-way conducting element D₁Is a rectifier diode or a one-way thyristor. The protection circuit can avoid damage of controller devices such as SiC SBD and the like, and reliability is improved.

When the voltage of the power grid is normal, the PFC circuit works normally, the voltage at the point A is about 310V, and the voltage at the point B is about 380V, namely the potential at the left side of the SiC SBD is low, and the potential at the right side is high, so that the SiC SBD cannot be conducted, and the current cannot flow through the D₁And R₁When MOSFET is usedWhen the MOSFET is switched on, the current passes through the path (II) and the path (III) to store energy for the inductor, and when the MOSFET is switched off, the current flows through the path (II) and the path (III) to supply energy to the electrolytic capacitor E₁And E₂Charging and boosting the voltage to the inductor L₁To E₁And E₂In (1). At this time, the surge current surge protection circuit (i.e., D)₁And R₁Series circuit) does not participate in the operation.

When the voltage of the power grid fluctuates to cause voltage drop, namely the voltage at the point A drops, the voltage at the point B is continuously consumed by the load, and the voltage drops, for example, the voltage at the point B drops from 380V to 200V. If the grid voltage returns to normal, the voltage at the point A returns to about 310V, and the voltage at the point B returns to 200V. At the moment, the voltage at the point A is higher than that at the point B, and a voltage difference of 310V-200V-110V is added to the PFC inductor L₁And the two ends of the SiC SBD, and the circuit impedance is very low at this moment if no surge current surge protection circuit (namely D) exists₁And R₁Series circuit), then the instantaneous heavy current all passes through route three, just easily surpasss the anti-surge repetitive peak current maximum value of SiC SBD, causes SiC SBD to damage, but adds anti-surge current surge protection circuit, just can shunt through route (r), namely passes through D₁And R₁Shunting, thereby avoiding SiC SBD damage.

The shunt proportion of the path I and the path III is related to the type selection of devices on the two paths and the routing of the step plate, and when different routing of the step plate are carried out, the parasitic inductance and the parasitic capacitance on the lines are different, and the parameters of the devices are also different.

R₁And D₁Can be flexibly adjusted according to actual board laying wiring and actual measurement results, and selects proper R₁And D₁Can effectively ensure the reasonable proportion of the path I and the path III and ensure D₁And SiC SBDs are not damaged by surge currents.

Alternatively, if the maximum current in the power factor correction circuit is I_maxFirst total resistance R of inductor and silicon carbide Schottky diode_{General 1}Second total resistance R of resistor and one-way conducting element_{General 2}Peak current maximum I of silicon carbide schottky diode_SBD，R_{General 1}And R_{General 2}The following conditions are satisfied:

I_maxR_{general 2}/(R_{General 1}+R_{General 2})≤I_SBD。

Optionally, the maximum current in the power factor correction circuit is I_maxFirst total resistance R of inductor and silicon carbide Schottky diode_{General 1}Second total resistance R of resistor and one-way conducting element_{General 2}Peak current maximum I of silicon carbide schottky diode_{Protection of}，R_{General 1}And R_{General 2}The following conditions are satisfied:

I_maxR_{general 1}/(R_{General 1}+R_{General 2})≤I_{Protection of}。

As shown in fig. 1, the PFC circuit further includes a filter capacitor C₁For high-frequency filtering, the filter capacitor C₁Connected between the direct current output anode 1 and the direct current output cathode 4.

Also shown in fig. 1 is the inclusion of two electrolytic capacitors E in the PFC circuit₁、E₂Two electrolytic capacitors E₁、E₂And the power supply is connected between the cathode of the SiC SBD and the ground GND for charging and discharging.

Also shown in FIG. 1 are a plurality of second resistors R₂-R₇And a protective capacitor C₂(ii) a And the second resistors and the protective capacitors are connected in series and then connected in parallel with the SiC SBD for protecting the SiC SBD.

Also shown in fig. 1 is a variable resistor R₈Voltage reducing resistor R₉And a protective capacitor C₃And the function of controlling the input current waveform of the PFC circuit is realized.

Because the SiC SBD has the advantages of very short reverse recovery time, very small reverse leakage current and the like, the SiC SBD is suitable for controllers of air conditioners and the like, but the surge current resistance of the SiC SBD is weak, and the SiC SBD can reliably work and avoid damage caused by surge current no matter the power grid environment by designing a protection circuit for resisting surge current impact.

Furthermore, the surge current impact resistant protection circuit can be calculated in theory and combined with the realThe boundary wiring board is wired and the actual measurement result is obtained, and the resistance R is flexibly adjusted₁And a rectifier diode D₁The value of (c) can effectively ensure that the path (I) and the path (III) are shunted according to a reasonable proportion and ensure D₁And SiC SBDs are not damaged by surge currents.

The embodiment of the invention also provides an external unit controller which is applied to an air conditioner and comprises the power factor correction circuit.

The embodiment of the invention also provides an air conditioner which comprises the outdoor unit controller.

Of course, those skilled in the art will understand that all or part of the processes in the methods of the above embodiments may be implemented by instructing the control device to perform operations through a computer, and the programs may be stored in a computer-readable storage medium, and when executed, the programs may include the processes of the above method embodiments, where the storage medium may be a memory, a magnetic disk, an optical disk, and the like.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.