WO2016192160A1

WO2016192160A1 - Device and method for protecting voltage surge of pec circuit in variable-frequency household electric apparatus

Info

Publication number: WO2016192160A1
Application number: PCT/CN2015/082870
Authority: WO
Inventors: 盛爽
Original assignee: 广东美的制冷设备有限公司; 美的集团股份有限公司
Priority date: 2015-05-29
Filing date: 2015-06-30
Publication date: 2016-12-08
Also published as: CN104967301B; CN104967301A

Abstract

A device and method for protecting a voltage surge of a PEC circuit in a variable-frequency household electric apparatus, the device comprising: a first voltage detection module (30) used to detect an input voltage of the PEC circuit; a current detection module (40) used to detect an input current of the PEC circuit; a second voltage detection module (50) used to detect an output voltage of the PEC circuit; a protection module (60) used to compare the input voltage and the output voltage and generate a first comparison result and compare the input current and a preset maximum allowable current to generate a second compare result and respectively control, according to the first compare result and the second compare result, the PEC circuit via a PEC control module (10) and a motor via a motor controller (20). The protection device can prevent the PEC circuit from being damaged and the machine from stopping when a voltage surge occurs.

Description

Voltage surge protection device and method for PFC circuit in frequency conversion household appliance

Technical field

The invention relates to the technical field of air conditioning systems, in particular to a voltage surge protection device for a PFC (Power Factor Correction) circuit in a frequency conversion household electrical appliance and a voltage swell of a PFC circuit used in a frequency conversion household electrical appliance Protection method.

Background technique

Frequency conversion is gradually becoming the trend of household appliances, especially air conditioners, refrigerators and washing machines. The frequency conversion technology can greatly save the electricity consumption of household appliances, and has the advantages of low noise and high performance.

Since the frequency conversion requires DC power supply, and the general commercial power is 220V AC power, it is necessary to convert the AC power into DC power through the rectifier circuit and the boost circuit to supply power to the load. In addition, in order to reduce the current harmonics and reactive power generated during the operation of the household electrical appliance, a PFC circuit is generally used to satisfy the boost function and the power factor correction function.

In the frequency conversion household electrical equipment, the PFC circuit is usually a Boost type PFC circuit, and the circuit mainly includes an inductor, a fast recovery diode and a power switching device. Among them, the power switching device is an important device for realizing the boost function and the power factor correction function. However, if the current when the power switching device is turned on is too large or the voltage when the power is turned off is too large, the power switching device is easily damaged, and therefore, it needs to be protected.

There are many reasons for the overvoltage or overcurrent of the power switching device. For example, the quality of the power supply used is one of the important aspects. When the power supply used, such as the mains voltage, is disturbed (the power supply voltage drops instantaneously or suddenly rises), or the software control algorithm is unreasonable or the processing is not timely (slow response), the power switching device may over-current or over-voltage, resulting in power switching. The device is damaged.

In the related art, the load power supply is disconnected by directly turning on the protection function to protect the power switching device. However, this method is suitable for terminal power grids or distributed power grids, such as township and rural power grids, because the grid voltage is unstable and the disturbance is frequent, and the household electrical appliances are difficult to work normally, especially the frequency conversion household appliances, and it is easy to frequently start and stop. It does not play a role in saving electricity, but also greatly affects the user's comfort and experience.

Summary of the invention

The present invention aims to solve at least one of the technical problems in the related art to some extent.

Therefore, an object of the present invention is to provide a voltage surge protection device for a PFC circuit in a frequency conversion household appliance, which can ensure that the PFC circuit is not damaged when the voltage is suddenly increased, and at the same time ensure that the frequency conversion household appliance does not stop running.

Another object of the present invention is to provide a voltage swell protection method for a PFC circuit in a frequency conversion household electrical appliance. law.

In order to achieve the above object, an embodiment of the present invention provides a voltage surge protection device for a PFC circuit in a frequency conversion home appliance, the frequency conversion home appliance including the PFC circuit, and controlling the PFC circuit to be turned on and off. a PFC control module, a motor, and a motor controller, the voltage swell protection device includes: a first voltage detecting module, the first voltage detecting module is configured to detect an input voltage of the PFC circuit; and a current detecting module, the current a detection module is configured to detect an input current of the PFC circuit; a second voltage detection module, the second voltage detection module is configured to detect an output voltage of the PFC circuit; and a protection module, wherein the protection module respectively a voltage detecting module, the current detecting module, the second voltage detecting module, the PFC control module and the motor controller are connected, wherein the protection module is configured to compare the input voltage and the output voltage Generating a first comparison result, and comparing the input current with a preset maximum allowable current to generate a second comparison result, to And for controlling said motor through said motor controller controls the PFC circuit according to the first comparison result and the second comparison result, respectively, by the PFC control module.

A voltage swell protection device for a PFC circuit in a frequency conversion household electrical appliance according to an embodiment of the present invention detects an input voltage of a PFC circuit through a first voltage detecting module, and detects an input current of the PFC circuit through the current detecting module, and passes the second The voltage detecting module detects an output voltage of the PFC circuit, and the protection module compares the input voltage and the output voltage to generate a first comparison result, and compares the input current with a preset maximum allowable current to generate a second comparison result, and according to the A comparison result and a second comparison result respectively control the PFC circuit through the PFC control module and control the motor through the motor controller, thereby effectively preventing the PFC circuit from being damaged when the voltage is swelled, and ensuring that the motor does not stop working and improves The reliability and user experience of frequency conversion home appliances.

According to an embodiment of the present invention, when the input voltage is greater than or equal to the output voltage and the input current is greater than or equal to the preset maximum allowable current, the protection module outputs a first protection signal to the The PFC control module is configured to cause the PFC control module to control the PFC circuit to be turned off, and output a second protection signal to the motor controller to cause the motor controller to control the motor to operate in a down frequency.

According to an embodiment of the present invention, the protection module outputs a first protection signal to the PFC control when the input voltage is greater than or equal to the output voltage and the input current is less than the preset maximum allowable current a module, wherein the PFC control module turns off the PFC circuit, and when the inductance L in the PFC circuit is less than a first preset inductance or the switching frequency of the PFC circuit is greater than a first preset frequency The motor controller controls the motor to run down in advance.

Or, when the input voltage is greater than or equal to the output voltage and the input current is less than the preset maximum allowable current, the protection module outputs a first protection signal to the PFC control module, so that the PFC control mode Blocking the PFC circuit, and controlling, by the motor controller, when the inductance L in the PFC circuit is greater than or equal to a first predetermined inductance and the switching frequency of the PFC circuit is less than or equal to a first preset frequency The motor operates normally at the preset frequency.

The first preset inductance may be 0.5-1 mH, and the first preset frequency may be 15-25 KHz.

According to an embodiment of the present invention, the protection module outputs a first protection signal to the PFC control when the input voltage is less than the output voltage and the input current is greater than or equal to the preset maximum allowable current And a module, wherein the PFC control module controls the PFC circuit to be turned off, and outputs a second protection signal to the motor controller to cause the motor controller to control the motor to operate in a down frequency.

According to an embodiment of the present invention, when the input voltage is less than the output voltage and the input current is less than the preset maximum allowable current, the PFC control module controls the PFC circuit to be turned on, the motor control The motor controls the motor to operate normally at a preset frequency.

In order to achieve the above object, another embodiment of the present invention provides a voltage swell protection method for a PFC circuit in a frequency conversion home appliance, the frequency conversion home appliance including the PFC circuit, and controlling the PFC circuit to be turned on and off. The PFC control module, the motor, the motor controller, the voltage swell protection method includes the steps of: detecting an input voltage of the PFC circuit, and detecting an input current of the PFC circuit; detecting an output voltage of the PFC circuit; And comparing the input voltage and the output voltage to generate a first comparison result, and comparing the input current with a preset maximum allowable current to generate a second comparison result, and according to the first comparison result And the second comparison result respectively controlling the PFC circuit by the PFC control module and controlling the motor by the motor controller.

A voltage swell protection method for a PFC circuit in a frequency conversion household appliance according to an embodiment of the present invention first detects an input voltage of a PFC circuit, detects an input current of the PFC circuit, and detects an output voltage of the PFC circuit, and then inputs the voltage and output The voltages are compared to generate a first comparison result, and the input current is compared with a preset maximum allowable current to generate a second comparison result, and the PFC circuit is respectively performed by the PFC control module according to the first comparison result and the second comparison result respectively Control and control the motor through the motor controller, which can effectively avoid the damage of the PFC circuit when the voltage rises, and ensure that the motor does not stop working, improving the reliability and user experience of the frequency conversion household appliances.

According to an embodiment of the present invention, when the input voltage is greater than or equal to the output voltage and the input current is greater than or equal to the preset maximum allowable current, outputting a first protection signal to the PFC control module, The PFC control module is configured to control the PFC circuit to be turned off, and output a second protection signal to the motor controller to cause the motor controller to control the motor to operate in a down frequency.

According to an embodiment of the invention, when the input voltage is greater than or equal to the output voltage and the input current When the preset maximum allowable current is less than the preset maximum allowable current, the first protection signal is output to the PFC control module, so that the PFC control module turns off the PFC circuit, and the inductance L in the PFC circuit is smaller than the first pre- The motor controller controls the motor to perform an early frequency down operation when the inductance or the switching frequency of the PFC circuit is greater than the first preset frequency.

Or when the input voltage is greater than or equal to the output voltage and the input current is less than the preset maximum allowable current, outputting a first protection signal to the PFC control module, so that the PFC control module is turned off. The PFC circuit, and when the inductance L in the PFC circuit is greater than or equal to a first preset inductance and the switching frequency of the PFC circuit is less than or equal to a first preset frequency, the motor controller controls the motor to follow Set the frequency to operate normally.

According to an embodiment of the present invention, when the input voltage is less than the output voltage and the input current is greater than or equal to the preset maximum allowable current, outputting a first protection signal to the PFC control module, so that The PFC control module controls the PFC circuit to be turned off, and outputs a second protection signal to the motor controller to cause the motor controller to control the motor to run down.

DRAWINGS

1 is a block diagram showing a voltage surge protection device for a PFC circuit in a frequency conversion household appliance according to an embodiment of the present invention;

2 is an equivalent circuit diagram of a power switching device IGBT (Insulated Gate Bipolar Transistor) turned on according to an embodiment of the present invention;

3 is an equivalent circuit diagram of a power switching device IGBT when turned off according to an embodiment of the present invention;

4 is a waveform diagram of an input current in one switching cycle when an input voltage is less than an output voltage according to an embodiment of the present invention;

5 is a waveform diagram of voltage and current of a PFC circuit under normal conditions, in accordance with an embodiment of the present invention;

6 is a waveform diagram of an input current in one switching period when an input voltage is greater than or equal to an output voltage, according to an embodiment of the present invention;

7 is a waveform diagram of voltage and current of a PFC circuit when a voltage of a FPC circuit is swelled according to an embodiment of the present invention;

8 is a waveform diagram of voltage and current of a PFC circuit protected by a voltage swell protection device when a voltage of a FPC circuit is swelled according to an embodiment of the present invention;

9 is a flow chart of a voltage swell protection method for a PFC circuit in a frequency conversion household appliance according to an embodiment of the present invention.

detailed description

The embodiments of the present invention are described in detail below, and the examples of the embodiments are illustrated in the drawings, wherein the same or similar reference numerals are used to refer to the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are intended to be illustrative of the invention and are not to be construed as limiting.

A voltage swell protection device for a PFC circuit in a frequency conversion home appliance and a voltage swell protection method for a PFC circuit in a frequency conversion home appliance according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

1 is a block schematic diagram of a voltage swell protection device for a PFC circuit in a frequency conversion household appliance according to an embodiment of the present invention, wherein the frequency conversion household appliance includes a PFC circuit, a PFC control module 10 that controls opening and closing of the PFC circuit, and a motor M, motor controller 20. As shown in FIG. 1, the voltage swell protection device for the PFC circuit in the inverter household electrical appliance includes a first voltage detecting module 30, a current detecting module 40, a second voltage detecting module 50, and a protection module 60.

The first voltage detecting module 30 is configured to detect an input voltage of the PFC circuit. The current detecting module 40 is configured to detect an input current of the PFC circuit. The second voltage detecting module 50 is configured to detect an output voltage of the PFC circuit. The protection module 60 is respectively connected to the first voltage detecting module 30, the current detecting module 40, the second voltage detecting module 50, the PFC control module 10 and the motor controller 20. The protection module 60 is configured to compare the input voltage and the output voltage to generate a first comparison result, and comparing the input current with the preset maximum allowable current to generate a second comparison result, and controlling the PFC circuit and passing the motor through the PFC control module 10 according to the first comparison result and the second comparison result, respectively The controller 20 controls the motor M.

It should be noted that when the frequency conversion household appliance is an air conditioner, the motor M is a compressor.

In an embodiment of the invention, the preset maximum allowable current can be calibrated according to actual conditions.

According to an embodiment of the invention, when the input voltage is greater than or equal to the output voltage and the input current is greater than or equal to the preset maximum allowable current, the protection module 60 outputs the first protection signal to the PFC control module 10 to cause the PFC control module 10 to control. The PFC circuit is turned off and a second protection signal is output to the motor controller 20 to cause the motor controller 20 to control the motor M to operate down.

According to an embodiment of the invention, when the input voltage is greater than or equal to the output voltage and the input current is less than the preset maximum allowable current, the protection module 60 outputs the first protection signal to the PFC control module 10 to cause the PFC control module 10 to turn off the PFC circuit. And when the inductance L in the PFC circuit is less than the first preset inductance or the switching frequency of the PFC circuit is greater than the first preset frequency, the motor M is controlled by the motor controller 20 to perform the frequency reduction operation in advance.

Alternatively, when the input voltage is greater than or equal to the output voltage and the input current is less than the preset maximum allowable current, the protection module 60 outputs a first protection signal to the PFC control module 10 to cause the PFC control module 10 to turn off the PFC circuit, and When the inductance L in the PFC circuit is greater than or equal to the first preset inductance and the switching frequency of the PFC circuit is less than or equal to the first preset frequency, the motor M is controlled by the motor controller 20 to operate normally according to the preset frequency. Among them, the preset frequency can be calibrated according to the actual situation.

In an embodiment of the invention, the first preset inductance may be 0.5-1 mH, and the first preset frequency may be 15-25 KHz. Preferably, the first preset inductance may be 1 mH, and the first preset frequency may be 20 kHz.

According to an embodiment of the invention, when the input voltage is less than the output voltage and the input current is greater than or equal to the preset maximum allowable current, the protection module 60 outputs the first protection signal to the PFC control module 10 to cause the PFC control module 10 to control the PFC circuit. The second protection signal is turned off and output to the motor controller 20 to cause the motor controller 20 to control the motor M to operate down.

According to an embodiment of the invention, when the input voltage is less than the output voltage and the input current is less than the preset maximum allowable current, the PFC control module 10 controls the PFC circuit to be turned on, and the motor controller 20 controls the motor M to operate normally according to the preset frequency.

It can be understood that the opening and closing of the PFC circuit refers to the opening and closing of a power switching device such as an IGBT in the PFC circuit.

Specifically, the Boost type PFC circuit shown in FIG. 1 mainly includes an inductor L, a fast recovery diode D1, a power switching device IGBT, and an electrolytic capacitor EC. The protection module 60 determines the switching state of the power switching device IGBT according to the input voltage V _in detected by the first voltage detecting module 30, the input current I _in detected by the current detecting module 40, and the output voltage V _out detected by the second voltage detecting module 50. The operating state of the motor M.

When the power switching device IGBT is in the on state, the equivalent circuit is shown in FIG. 2, and the voltage on the inductor L is the voltage output by the AC power source after being rectified by the diode rectifier bridge, that is, the input voltage detected by the first voltage detecting module 30. V _in . Since the input voltage V _{in is} always greater than zero, the current flowing through the inductor L gradually rises, that is, the input current I _in detected by the current detecting module 40 gradually increases; when the power switching device IGBT is in the off state, the equivalent circuit thereof 3, the voltage on the inductance L of the difference between the input voltage V _in the PFC circuit and the output voltage V _out. Since the Boost type PFC circuit only has a boost function, under normal operating conditions, the input voltage V _{in of the} PFC circuit is smaller than the output voltage V _out , and the voltage on the inductor L is reversed. At this time, the current flowing through the inductor L will gradually The falling, that is, the input current I _in detected by the current detecting module 40 gradually decreases. Therefore, in one switching cycle of the power switching device IGBT, the waveform of the input current I _in is as shown _in FIG. 4 , when the power switching device IGBT is turned on, the rising slope of the input current I _in is tan α=V _in /L ₀ ; When the power switching device IGBT is turned off, the falling slope of the input current I _in is tan β=(V _out −V _in )/L ₀ , where L ₀ is the inductance value of the inductor L.

When the AC power supply voltage is normal, by controlling the power switching device and the IGBT is turned off so that the input voltage V _in and the input current I _in the same phase, while ensuring output voltage V _out to meet the operational requirements of the motor M, at this time, the input The waveforms of the voltage V _in , the input current I _{in ,} and the output voltage V _out are as shown in FIG. 5.

When the AC power supply voltage suddenly rises, the input voltage V _in may exceed the output voltage V _out . At this time, even if the control power switching device IGBT is turned off, since the voltage on the inductor L (V _in -V _out ) is greater than zero, the flow The current through inductor L will continue to rise, as shown in Figure 6. Further, due to the presence of the electrolytic capacitor EC, so that the output voltage V _out can not rise immediately, this time, the current flowing through the inductor L rises rapidly until the over-current, as shown in FIG. It should be noted that the time interval t ₁ -t ₂ shown in FIG. 7 is a time interval in which the input voltage V _{in is} greater than the output voltage V _out , and in this time interval, if the power switching device IGBT is in an on state, the input current is input. I _in will rise faster.

In order to solve the overcurrent phenomenon in the current flowing through the inductor L caused by the sudden rise of the AC power supply voltage, the input voltage V _in the Boost-type PFC circuit is greater than the output voltage V _out , in the embodiment of the present invention, the protection module 60 is The input voltage V _in which the voltage detecting module 30 detects _in real time, the input current I _in detected by the current detecting module 40 in real time, and the output voltage V _out detected by the second voltage detecting module 50 in real time perform protection control on the PFC circuit and the motor M.

Specifically, the protection module 60 compares the detected input voltage V _in with the output voltage V _out to output a first protection signal PFC_PRT_FLAG to the PFC control module 10, and the PFC control module 10 pairs the power switching device IGBT according to the first protection signal PFC_PRT_FLAG. Take control. Wherein, when the input voltage V _{in is} greater than or equal to the output voltage V _out , the protection of the power switching device IGBT is turned on, and the first protection signal PFC_PRT_FLAG is set to 1, and the duty signal of the driving signal of the power switching device IGBT output by the PFC control module 10 is occupied. When the ratio D is 0, the PFC circuit is turned off; when the input voltage V _{in is} smaller than the output voltage V _out , the protection of the power switching device IGBT is turned off, and the first protection signal PFC_PRT_FLAG is cleared, and the driving signal of the power switching device IGBT is controlled by the PFC control module. 10 controls. Meanwhile, in order to prevent an overcurrent phenomenon from occurring due to an excessive input current I _in , the protection module 60 also determines the input current I _in and outputs a second protection signal MTR_PRT_FLAG to the motor controller 20, and the motor controller 20 according to the second The protection signal MTR_PRT_FLAG controls the motor M. Wherein, when the input current I _{in is} greater than or equal to the preset maximum allowable current I _max , the speed of the motor M is reduced to reduce the load, thereby reducing the input current I _{in to} ensure that the motor M does not stop running; when the input current When I _{in is} less than the preset maximum allowable current I _max , the motor M returns to the normal speed and operates at the original load. It should be noted that when the input current I _{in is} greater than or equal to the preset maximum allowable current I _max , in order to prevent damage when the power switching device IGBT is turned on, whether the input voltage V _in is greater than the output voltage V _{out is} required to be ensured. The power switching device IGBT is in an off state.

In an embodiment of the present invention, the protective module 60 according to the control logic shown in Table 1, and the motor M for controlling a PFC circuit to ensure PFC circuit can effectively reduce the input current I _in at AC power source voltage suddenly rises, so as to ensure The PFC circuit does not flow, and at the same time ensures that the motor M does not stop running.

Table 1

Table 1 will be described in detail below with reference to specific examples.

(1) V _out >V _in and I _in <I _max

This state is the normal operating state of the Boost type PFC circuit. Boost function of Boost PFC circuit so that the output voltage V _out is greater than the input voltage V _in, and, input current I _in normal operating conditions is less than the predetermined maximum permissible current I _max The maximum allowed current of the power switching devices of IGBT, the When the PFC circuit is normally turned on, the motor M operates normally according to the preset frequency.

(2) V _out ≤ V _in and I _in < I _max

When the AC power supply voltage suddenly rises as the grid voltage is unstable, the rise of the output voltage V _out lags behind the input voltage V _in due to the presence of the electrolytic capacitor EC, and therefore, the output voltage V _{out is} less than the input voltage V _in , At this time, the voltage on the inductor L is positive, and the current flowing through the inductor L will always rise regardless of whether the power switching device IGBT is turned off, but since the current flowing through the inductor L cannot be abruptly changed, therefore, when the Boost type PFC when the circuit enters the normal operating state by the over-voltage condition, the input current I _in is less than the predetermined maximum permissible current I _max.

Assuming that the power switching device IGBT is in an on state, the amount of current rise in one switching cycle of the power switching device IGBT satisfies the following formula (1):

Where f is the switching frequency and D is the IGBT turn-on duty.

Since the AC power source voltage suddenly rises, the input voltage V _in magnitude | V _in | much greater than the difference between the magnitude of the input voltage V _in and the output voltage V _out of | V _in -V _out |, and therefore, input current I _in is increased fast. In order to prevent the input current I _{in from} rising too fast while protecting the power switching device IGBT from damage, the power switching device IGBT needs to be turned off in this state, and the current rise amount in one switching cycle of the power switching device IGBT satisfies the following Formula (2):

It can be seen from the above formula (1) and formula (2) that when the power switching device IGBT is in the off state, the input current I _in rises relatively slowly, and at this time, the motor M can be controlled to be down-converted by the motor controller 20 in advance. Or operate normally at the preset frequency. Wherein, when the inductance of the inductor L is less than 1 mH, for example, L0 is 1 uH-1 mH (ie, L0 is small, the overcurrent phenomenon is more likely to occur), the motor M is required to be controlled by the motor controller 20 to be down-converted in advance, or when the PFC circuit is When the switching frequency of the IGBT is greater than 20KHz, for example, 20-100KHz (ie, the switching frequency is higher, L0 is smaller, and the overcurrent phenomenon is more likely to occur), the motor M is required to be controlled by the motor controller 20 to reduce the frequency in advance; and when the inductance of the inductor L is When the amount is greater than or equal to 1 mH and the switching frequency of the PFC circuit, ie, the IGBT, is less than or equal to 20 KHz, the motor M is controlled by the motor controller 20 to operate normally according to the preset frequency.

Specifically, when the inductance value of the inductor L is relatively small (for example, when the switching frequency of the PFC circuit is greater than 20 kHz when the high frequency PFC circuit is used), even if the power switching device IGBT is always turned off, the rising speed of the input current I _in is also Will be very fast. Further, when a relatively large electrolytic capacitor EC, the rising speed of the output voltage V _out is relatively slow, it is possible to output voltage V _out will be less than the input voltage V _in a long period of time, when required by the motor controller 20 controls the motor M Run down in advance to avoid overcurrent.

In addition to the above, in order to avoid the motor M frequency down operation (such as air conditioning cooling effect is worse) affecting the user experience, electricity The machine controller 20 can control the normal operation of the motor M according to a preset frequency.

(3) V _out ≤ V _in and I _in ≥ I _max

If the output voltage V _{out has} not risen above the input voltage V _in and the input current I _in has exceeded the preset maximum allowable current I _max , for example, when the grid voltage suddenly rises by more than 100V, and the inductance of the inductor L is relatively small, The capacitance of the electrolytic capacitor EC is large, and this situation is very likely to occur. At this time, the PFC control module 10 is required to control the PFC circuit to be turned off, and the motor controller 20 is controlled to reduce the frequency of the motor M, thereby ensuring that the power switching device IGBT is not damaged, and on the other hand, the diode rectifier bridge and the fast recovery diode D1 and the like. The overcurrent capability is much larger than that of the power switching device IGBT. Therefore, the motor M can be operated for a further period of time by down-conversion operation. If the input current I _in continues to rise, the power supply needs to be disconnected to protect the variable frequency home appliance.

(4) V _out >V _in and I _in ≥I _max

If the output voltage V _out has risen above the input voltage V _in but the input current I _{in has} not recovered to the normal value, in order to protect the power switching device IGBT, it is necessary to ensure that the power switching device IGBT is always in the off state. At this time, since the output voltage V _{out is} greater than the input voltage V _in , the voltage on the inductor L is reversed, so that the current flowing through the inductor L gradually decreases, and the current reduction amount in one switching cycle of the power switching device IGBT satisfies The following formula (3):

At the same time, in order to quickly restore the input current I _in to a normal value, the motor controller 20 is required to control the motor M to operate down.

The waveforms of the input voltage V _in , the input current I _{in ,} and the output voltage V _out of the protected PFC circuit are as shown in FIG. Comparison with FIG. 7, when the AC power supply voltage rises abruptly, can effectively reduce the input current I _in current and power switching devices of IGBT, and to ensure non-stop operation.

Further, in order to protect the safety of the device other than the power switching device IGBT and prevent the device from being damaged, a first current threshold I _max2 may be added, which is set according to the maximum allowable current of the diode rectifier bridge and the fast recovery diode D1. set. Since the overcurrent capability of the diode rectifier bridge and the fast recovery diode D1 is much larger than that of the power switching device IGBT, the first current threshold I _{max2 is} greater than the maximum allowable current of the power switching device IGBT, that is, the preset maximum allowable current I _max .

The control logic of the protection module 60 is as shown in Table 2.

Table 2

When V _out >V _in and I _in <I _max , it is the normal working state of the Boost type PFC circuit, and at this time, the motor M is controlled by the motor controller 20 to operate normally according to the preset frequency.

When V _out ≤ V _in and I _in < I _max , the PFC circuit protection module 10 controls the PFC circuit to be turned off, and the motor controller 20 controls the motor M to operate normally according to a preset frequency or to perform a frequency reduction operation in advance. Wherein, when the inductance value of the inductor L is relatively small and the capacitance value of the electrolytic capacitor EC is relatively large, the motor M is controlled to be down-converted by the motor controller 20, otherwise, the motor M is controlled by the motor controller 20 to operate normally according to the preset frequency. .

When V _out >V _in and I _max ≤I _in <I _max2 , the power switching device IGBT is first turned off to protect it from damage. In addition, since the output voltage V _{out is} greater than the input voltage V _in such that the voltage on the inductor L is reversed, the input current I _in will gradually drop to a normal value, and the motor M can be down-converted by reducing the rotational speed command ω ^* to The input current I _in can be quickly restored to a normal value.

When V _out ≤ V _in and I _max ≤ I _in < I _max2 , the control mode of the motor down- _{conversion operation} is further determined by the preset intermediate current threshold I _max21 . When V _out ≤V _in and I _max ≤I _in <I _max21 , the power switching device IGBT is turned off to protect it from damage, and the motor M is down- _converted by reducing the rotational speed command ω ^* ; when V _out ≤V _In and I _{max21 ≤I} _in <I _max2 , the power switching device IGBT is first turned off to protect it from damage, and in addition, although the input current I _{in has} not reached the first current threshold I _max2 , it is already close to the first current threshold I _max2 , and the response speed of the current regulation loop is much faster than the response speed of the speed regulation loop. Therefore, the electromagnetic torque generated by the motor M can be quickly reduced by changing the current command I _q ^* to achieve fast frequency reduction. purpose.

When I _in ≥ I _max2 , regardless of whether the input voltage V _in is greater than the output voltage V _out , the input current I _in has exceeded the capability of the device in the variable frequency household electrical appliance, and therefore must be powered off.

In summary, the voltage swell protection device for the PFC circuit in the frequency conversion household appliance according to the embodiment of the present invention detects the input voltage of the PFC circuit through the first voltage detection module, and detects the input current of the PFC circuit through the current detection module. And detecting, by the second voltage detecting module, an output voltage of the PFC circuit, the protection module comparing the input voltage and the output voltage to generate a first comparison result, and comparing the input current with a preset maximum allowable current to generate a second comparison As a result, and according to the first comparison result and the second comparison result, the PFC circuit and the motor are respectively controlled by the PFC control module and the motor controller, thereby effectively preventing the current from being excessively damaged and damaging the power switching device IGBT and the like when the voltage is swelled. The device, and in the case of ensuring that the device is not damaged, ensures that the PFC circuit works normally, avoids stopping the motor due to excessive protection, and improves the reliability and user experience of the frequency conversion home appliance.

9 is a flow chart of a voltage swell protection method for a PFC circuit in a frequency conversion household appliance according to an embodiment of the present invention, wherein the frequency conversion household appliance includes a PFC circuit, a PFC control module that controls opening and closing of the PFC circuit, a motor, and a motor. Controller. As shown in FIG. 9, the voltage swell protection method for the PFC circuit in the frequency conversion household appliance includes the following steps:

S1, detecting the input voltage of the PFC circuit and detecting the input current of the PFC circuit.

S2, detecting the output voltage of the PFC circuit.

S3, comparing the input voltage and the output voltage to generate a first comparison result, comparing the input current with a preset maximum allowable current to generate a second comparison result, and respectively passing the first comparison result and the second comparison result respectively The PFC control module controls the PFC circuit and controls the motor through the motor controller.

It should be noted that when the frequency conversion household appliance is an air conditioner, the motor is a compressor.

According to an embodiment of the present invention, when the input voltage is greater than or equal to the output voltage and the input current is greater than or equal to the preset maximum allowable current, the first protection signal is output to the PFC control module, so that the PFC control module controls the PFC circuit to be turned off. And outputting a second protection signal to the motor controller to cause the motor controller to control the motor to run down.

According to an embodiment of the present invention, when the input voltage is greater than or equal to the output voltage and the input current is less than the preset maximum allowable current, the first protection signal is output to the PFC control module, so that the PFC control module turns off the PFC circuit, and When the inductance L in the PFC circuit is less than the first preset inductance or the switching frequency of the PFC circuit is greater than the first preset frequency, the motor controller controls the motor to perform the frequency reduction operation in advance.

Or, when the input voltage is greater than or equal to the output voltage and the input current is less than the preset maximum allowable current, outputting the first protection signal to the PFC control module, so that the PFC control module turns off the PFC circuit, and in the PFC circuit The motor controller controls the motor to operate normally according to a preset frequency when the inductance L is greater than or equal to the first preset inductance and the switching frequency of the PFC circuit is less than or equal to the first preset frequency.

The first preset inductance may be 0.5-1 mH, and the first preset frequency may be 15-25 KHz. Preferably, the first preset inductance may be 1 mH, and the first preset frequency may be 20 kHz.

According to an embodiment of the invention, when the input voltage is less than the output voltage and the input current is greater than or equal to the preset maximum allowable current, the first protection signal is output to the PFC control module, so that the PFC control module controls the PFC circuit to be turned off, and outputs The second protection signal is sent to the motor controller to cause the motor controller to control the motor to run down.

According to an embodiment of the invention, when the input voltage is less than the output voltage and the input current is less than the preset maximum allowable current, the PFC control module controls the PFC circuit to be turned on, and the motor controller controls the motor to operate normally according to the preset frequency.

According to a specific example of the present invention, as shown in FIG. 1, the Boost type PFC circuit mainly includes an inductor L, a fast recovery diode D1, a power switching device IGBT, and an electrolytic capacitor EC. In the circuit, the input voltage V _in and the output voltage V _{out of the} PFC circuit can be respectively obtained by a resistor voltage division method, and the input current I _{in of the} PFC circuit is obtained by the resistance sampling method, and according to the input voltage V _{in the} obtained PFC circuit The input current I _in and the output voltage V _{out are} used to determine the switching state of the power switching device IGBT and the operating state of the motor.

When the power switching device IGBT is in the on state, the equivalent circuit is shown in Figure 2. The voltage on the inductor L is the voltage output by the AC power source after being rectified by the diode rectifier bridge, that is, the input voltage V _in . Since the input voltage V _{in is} always greater than zero, the current flowing through the inductor L gradually rises, that is, the input current I _in gradually increases; when the power switching device IGBT is in the off state, the equivalent circuit thereof is as shown in FIG. 3 . voltage across the inductor L is the difference between the input voltage of the PFC circuit and the V _in the output voltage V _out. Since the Boost type PFC circuit only has a boost function, under normal operating conditions, the input voltage V _{in of the} PFC circuit is smaller than the output voltage V _out , and the voltage on the inductor L is reversed. At this time, the current flowing through the inductor L will gradually The drop, that is, the input current I _in gradually decreases. Therefore, in one switching cycle of the power switching device IGBT, the waveform of the input current I _in is as shown _in FIG. 4 , when the power switching device IGBT is turned on, the rising slope of the input current I _in is tan α=V _in /L ₀ ; When the power switching device IGBT is turned off, the falling slope of the input current I _in is tan β=(V _out −V _in )/L ₀ , where L ₀ is the inductance value of the inductor L.

When the AC power supply voltage is normal, by controlling the power switching device and the IGBT is turned off so that the input voltage V _in and the input current I _in the same phase, while ensuring output voltage V _out to meet the operational requirements of the motor case, the input voltage The waveform of V _in , the input current I _{in ,} and the output voltage V _out is as shown in FIG. 5.

In order to solve the overcurrent phenomenon in the current flowing through the inductor L caused by the sudden rise of the AC power supply voltage, the input voltage V _{in of} the Boost-type PFC circuit is greater than the output voltage V _out , in the embodiment of the present invention, the input according to the real-time detection The voltage V _in , the input current I _{in ,} and the output voltage V _out provide protection control for the PFC circuit and the motor.

Specifically, the detected input voltage V _{in is} compared with the output voltage V _out to output a first protection signal PFC_PRT_FLAG to the PFC control module, and the PFC control module controls the power switching device IGBT according to the first protection signal PFC_PRT_FLAG. Wherein, when the input voltage V _{in is} greater than or equal to the output voltage V _out , the protection of the power switching device IGBT is turned on, the first protection signal PFC_PRT_FLAG is set to 1, and the duty ratio of the driving signal of the power switching device IGBT output by the PFC control module at this time D is 0, the PFC circuit is turned off; when the input voltage V _{in is} smaller than the output voltage V _out , the protection of the power switching device IGBT is turned off, and the first protection signal PFC_PRT_FLAG is cleared, and the driving signal of the power switching device IGBT is controlled by the PFC control module. . Meanwhile, in order to prevent excessive input current I _in and cause an overcurrent occurs, the input current I _in is also judged, and outputs the second MTR_PRT_FLAG protection signal to the motor controller, the motor controller according to a second motor protection signal MTR_PRT_FLAG Take control. Wherein, when the input current I _{in is} greater than or equal to the preset maximum allowable current I _max , the input speed I _{in is} reduced by reducing the rotational speed of the motor, thereby ensuring that the motor does not stop running; when the input current I _in When it is less than the preset maximum allowable current I _max , the motor returns to the normal speed and runs at the original load. It should be noted that when the input current I _{in is} greater than or equal to the preset maximum allowable current I _max , in order to prevent damage when the power switching device IGBT is turned on, whether the input voltage V _in is greater than the output voltage V _{out is} required to be ensured. The power switching device IGBT is in an off state.

In an embodiment of the present invention, the PFC circuit, and controls the motor according to the control logic shown in Table 1, to ensure that the PFC circuit can effectively reduce the input current I _in flowing through the power switching device when the AC power supply voltage rises abruptly The current of the IGBT ensures that the PFC circuit does not flow, and the motor is not stopped. Table 1 will be described in detail below with reference to specific examples.

(1) V _out >V _in and I _in <I _max

This state is the normal operating state of the Boost type PFC circuit. Boost function of Boost PFC circuit so that the output voltage V _out is greater than the input voltage V _in, and, input current I _in normal operating conditions is less than the predetermined maximum permissible current I _max The maximum allowed current of the power switching devices of IGBT, the When the PFC circuit is normally turned on, the motor operates normally according to the preset frequency.

(2) V _out ≤ V _in and I _in < I _max

Assuming that the power switching device IGBT is in an on state, the amount of current rise in one switching cycle of the power switching device IGBT satisfies the above formula (1). Since the AC power source voltage suddenly rises, the input voltage V _in magnitude | V _in | much greater than the difference between the magnitude of the input voltage V _in and the output voltage V _out of | V _in -V _out |, and therefore, input current I _in is increased fast. In order to prevent the input current I _{in from} rising too fast and protecting the power switching device IGBT from damage, the power switching device IGBT needs to be turned off in this state, and the current rise amount in one switching cycle of the power switching device IGBT satisfies the above formula. (2).

It can be seen from the above formula (1) and formula (2) that when the power switching device IGBT is in the off state, the input current I _in rises relatively slowly. At this time, the motor controller can be used to control the motor to run down in advance or according to The preset frequency is operating normally. Wherein, when the inductance of the inductor L is less than 1 mH, for example, L0 is 1 uH-1 mH (ie, L0 is small, the more likely the overcurrent phenomenon occurs), the motor controller is required to control the motor to perform early frequency down operation, or when the PFC circuit is an IGBT. When the switching frequency is greater than 20KHz, for example, 20-100KHz (ie, the switching frequency is higher, L0 is smaller, the more likely the overcurrent phenomenon occurs), the motor controller needs to control the motor to reduce the frequency in advance; and when the inductance of the inductor L is greater than or equal to 1mH When the switching frequency of the PFC circuit, ie, the IGBT, is less than or equal to 20 KHz, the motor controller controls the motor to operate normally according to the preset frequency.

Specifically, when the inductance value of the inductor L is relatively small (for example, when the switching frequency of the PFC circuit is greater than 20 kHz when the high frequency PFC circuit is used), even if the power switching device IGBT is always turned off, the rising speed of the input current I _in is also Will be very fast. Further, when a relatively large electrolytic capacitor EC, the rising speed of the output voltage V _out is relatively slow, it is possible to output voltage V _out will be less than the input voltage V _in a long period of time, this time is necessary to control the motor in advance by lowering the motor controller Frequency operation to avoid overcurrent phenomena.

In addition to the above, in order to avoid the motor frequency reduction operation (such as air conditioning cooling effect is worse) affecting the user experience, the motor controller can control the normal operation of the motor according to the preset frequency.

(3) V _out ≤ V _in and I _in ≥ I _max

If the output voltage V _{out has} not risen above the input voltage V _in and the input current I _in has exceeded the preset maximum allowable current I _max , for example, when the grid voltage suddenly rises by more than 100V, and the inductance of the inductor L is relatively small, The capacitance of the electrolytic capacitor EC is large, and this situation is very likely to occur. At this time, the PFC control module is required to control the PFC circuit to be turned off, and the motor controller is controlled to reduce the frequency of the motor. On the one hand, the power switching device IGBT is not damaged, and on the other hand, the device is overcurrent due to the diode rectifier bridge and the fast recovery diode D1. The capability is much larger than the power switching device IGBT, so the motor can be operated for a further period of time by down-conversion operation. If the input current I _in continues to rise, the power supply needs to be disconnected to protect the variable frequency home appliance.

(4) V _out >V _in and I _in ≥I _max

If the output voltage V _out has risen above the input voltage V _in but the input current I _{in has} not recovered to the normal value, in order to protect the power switching device IGBT, it is necessary to ensure that the power switching device IGBT is always in the off state. At this time, since the output voltage V _{out is} greater than the input voltage V _in , the voltage on the inductor L is reversed, so that the current flowing through the inductor L gradually decreases, and the current reduction amount in one switching cycle of the power switching device IGBT satisfies The above formula (3). At the same time, in order to quickly restore the input current I _in to the normal value, the motor controller is required to control the motor to reduce the frequency.

Further, in order to protect the safety of the device other than the power switching device IGBT and prevent the device from being damaged, a first current threshold I _max2 may be added, which is set according to the maximum allowable current of the diode rectifier bridge and the fast recovery diode D1. set. Since the overcurrent capability of the diode rectifier bridge and the fast recovery diode D1 is much larger than that of the power switching device IGBT, the first current threshold I _{max2 is} greater than the maximum allowable current of the power switching device IGBT, that is, the preset maximum allowable current I _max . Its control logic is shown in Table 2 above.

When V _out >V _in and I _in <I _max , it is the normal working state of the Boost type PFC circuit. At this time, the motor controller controls the motor to operate normally according to the preset frequency.

When V _out ≤V _in and I _in <I _max , the PFC circuit protection module controls the PFC circuit to be turned off, and the motor controller controls the motor to operate normally according to the preset frequency or to perform the frequency reduction operation in advance. Wherein, when the inductance value of the inductor L is relatively small and the capacitance value of the electrolytic capacitor EC is relatively large, the motor controller controls the motor to perform the frequency reduction operation in advance, otherwise, the motor controller controls the motor to operate normally according to the preset frequency.

When V _out >V _in and I _max ≤I _in <I _max2 , the power switching device IGBT is first turned off to protect it from damage. In addition, since the output voltage V _{out is} greater than the input voltage V _in such that the voltage on the inductor L is reversed, the input current I _in will gradually drop to a normal value, and the motor can be down-converted by reducing the rotational speed command ω ^* so that The input current I _in can quickly return to normal.

When V _out ≤ V _in and I _max ≤ I _in < I _max2 , the control mode of the motor down- _{conversion operation} is further determined by the preset intermediate current threshold I _max21 . When V _out ≤V _in and I _max ≤I _in <I _max21 , the power switching device IGBT is turned off to protect it from damage, and the motor is down- _converted by reducing the rotational speed command ω ^* ; when V _out ≤V _in And when I _{max21 ≤I} _in <I _max2 , the power switching device IGBT is first turned off to protect it from damage, and in addition, although the input current I _{in has} not reached the first current threshold I _max2 , it is already close to the first current threshold I _Max2 , and the response speed of the current regulation loop is much faster than the response speed of the speed regulation loop. Therefore, the electromagnetic torque generated by the motor can be quickly reduced by changing the current command I _q ^* to achieve fast frequency reduction.

A voltage swell protection method for a PFC circuit in a frequency conversion household appliance according to an embodiment of the present invention first detects an input voltage of a PFC circuit, detects an input current of the PFC circuit, and detects an output voltage of the PFC circuit, and then inputs the input The voltage and the output voltage are compared to generate a first comparison result, and the input current is compared with a preset maximum allowable current to generate a second comparison result, and the PFC control module pair is respectively passed according to the first comparison result and the second comparison result respectively The PFC circuit controls and controls the motor through the motor controller, thereby effectively preventing the current switching device from IGBT and other devices when the voltage is suddenly increased, and ensuring the PFC while ensuring that the device is not damaged. The circuit works normally to avoid the motor from being stopped due to excessive protection, which improves the reliability and user experience of the frequency conversion household appliances.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " After, "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inside", "Outside", "Clockwise", "Counterclockwise", "Axial", The orientation or positional relationship of the "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the drawings, and is merely for convenience of description of the present invention and simplified description, and does not indicate or imply the indicated device or component. It must be constructed and operated in a particular orientation, and is not to be construed as limiting the invention.

Moreover, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, features defining "first" or "second" may include at least one of the features, either explicitly or implicitly. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless specifically defined otherwise.

In the present invention, the terms "installation", "connected", "connected", "fixed" and the like shall be understood broadly, and may be either a fixed connection or a detachable connection, unless explicitly stated and defined otherwise. , or integrated; can be mechanical or electrical connection; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction of two elements, unless otherwise specified Limited. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood on a case-by-case basis.

In the present invention, the first feature "on" or "under" the second feature may be a direct contact of the first and second features, or the first and second features may be indirectly through an intermediate medium, unless otherwise explicitly stated and defined. contact. Moreover, the first feature "above", "above" and "above" the second feature may be that the first feature is directly above or above the second feature, or merely that the first feature level is higher than the second feature. The first feature "below", "below" and "below" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely that the first feature level is less than the second feature.

In the description of the present specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means a specific feature described in connection with the embodiment or example. A structure, material or feature is included in at least one embodiment or example of the invention. In this specification, a schematic representation of the above terms It is not necessary to be directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, various embodiments or examples described in the specification, as well as features of various embodiments or examples, may be combined and combined.

Although the embodiments of the present invention have been shown and described, it is understood that the above-described embodiments are illustrative and are not to be construed as limiting the scope of the invention. The embodiments are subject to variations, modifications, substitutions and variations.

Claims

A voltage surge protection device for a power factor correction PFC circuit in a frequency conversion household appliance, characterized in that the frequency conversion household appliance comprises the PFC circuit, a PFC control module that controls opening and closing of the PFC circuit, a motor, The motor controller, the voltage swell protection device comprises:

a first voltage detecting module, wherein the first voltage detecting module is configured to detect an input voltage of the PFC circuit;

a current detecting module, wherein the current detecting module is configured to detect an input current of the PFC circuit;

a second voltage detecting module, wherein the second voltage detecting module is configured to detect an output voltage of the PFC circuit;

a protection module, wherein the protection module is respectively connected to the first voltage detection module, the current detection module, the second voltage detection module, the PFC control module, and the motor controller, where the protection module is used Comparing the input voltage and the output voltage to generate a first comparison result, and comparing the input current with a preset maximum allowable current to generate a second comparison result, and according to the first comparison result and The second comparison result controls the PFC circuit through the PFC control module and controls the motor through the motor controller.
The voltage swell protection device for a power factor correction PFC circuit in a frequency conversion household appliance according to claim 1, wherein when said input voltage is greater than or equal to said output voltage and said input current is greater than or equal to The protection module outputs a first protection signal to the PFC control module when the preset maximum allowable current is described, so that the PFC control module controls the PFC circuit to be turned off, and outputs a second protection signal to the motor control And causing the motor controller to control the motor to operate in a down frequency.
The voltage swell protection device for a power factor correction PFC circuit in a frequency conversion household appliance according to claim 1, wherein when said input voltage is greater than or equal to said output voltage and said input current is less than said When the maximum allowable current is set, the protection module outputs a first protection signal to the PFC control module, so that the PFC control module turns off the PFC circuit, and the inductance L in the PFC circuit is smaller than the first pre- When the inductance or the switching frequency of the PFC circuit is greater than the first preset frequency, the motor is controlled to perform the frequency reduction operation by the motor controller.
The voltage swell protection device for a power factor correction PFC circuit in a frequency conversion household appliance according to claim 1, wherein when said input voltage is greater than or equal to said output voltage and said input current is less than said When the maximum allowable current is set, the protection module outputs a first protection signal to the PFC control module, so that the PFC control module turns off the PFC circuit, and the inductance L in the PFC circuit is greater than or equal to the first The motor is controlled to operate normally according to the preset frequency by the motor controller when the inductance is preset and the switching frequency of the PFC circuit is less than or equal to the first preset frequency.
A voltage swell protection device for a power factor correction PFC circuit in a frequency conversion household appliance according to claim The protection module outputs a first protection signal to the PFC control module when the input voltage is less than the output voltage and the input current is greater than or equal to the preset maximum allowable current. The PFC control module is configured to control the PFC circuit to be turned off, and output a second protection signal to the motor controller to cause the motor controller to control the motor to operate in a down frequency.
The voltage swell protection device for a power factor correction PFC circuit in a variable frequency household electrical appliance according to claim 1, wherein when said input voltage is less than said output voltage and said input current is less than said predetermined When the maximum allowable current, the PFC control module controls the PFC circuit to be turned on, and the motor controller controls the motor to operate normally according to a preset frequency.
The voltage swell protection device for a power factor correction PFC circuit in a frequency conversion household electrical appliance according to claim 3 or 4, wherein the first predetermined inductance is 0.5-1 mH, the first preset The frequency is 15-25KHz.
A voltage surge protection method for a power factor correction PFC circuit in a frequency conversion household appliance, characterized in that the frequency conversion household appliance comprises the PFC circuit, a PFC control module that controls opening and closing of the PFC circuit, a motor, The motor controller, the voltage swell protection method comprises the following steps:

Detecting an input voltage of the PFC circuit and detecting an input current of the PFC circuit;

Detecting an output voltage of the PFC circuit;

Comparing the input voltage and the output voltage to generate a first comparison result, and comparing the input current with a preset maximum allowable current to generate a second comparison result, and according to the first comparison result and The second comparison result controls the PFC circuit through the PFC control module and controls the motor through the motor controller.
The voltage swell protection method for a power factor correction PFC circuit in a variable frequency household electrical appliance according to claim 8, wherein when said input voltage is greater than or equal to said output voltage and said input current is greater than or equal to Outputting a first protection signal to the PFC control module when the preset maximum allowable current is applied, so that the PFC control module controls the PFC circuit to be turned off, and outputs a second protection signal to the motor controller, so that The motor controller controls the motor to operate in a down frequency.
A voltage swell protection method for a power factor correction PFC circuit in a frequency conversion household appliance according to claim 8, wherein when said input voltage is greater than or equal to said output voltage and said input current is less than said When the maximum allowable current is set, the first protection signal is output to the PFC control module, so that the PFC control module turns off the PFC circuit, and the inductance L in the PFC circuit is smaller than the first preset inductance or The motor controller controls the motor to perform an early frequency down operation when the switching frequency of the PFC circuit is greater than the first preset frequency.
A voltage swell protection method for a power factor correction PFC circuit in a frequency conversion household appliance according to claim 8, wherein when said input voltage is greater than or equal to said output voltage and said input current is less than said a maximum allowable current, outputting a first protection signal to the PFC control module, so that the PFC control module turns off the PFC circuit, and an inductance L in the PFC circuit is greater than or equal to a first preset inductance And the motor controller controls the motor to operate normally according to the preset frequency when the switching frequency of the PFC circuit is less than or equal to the first preset frequency.
A voltage swell protection method for a power factor correction PFC circuit in a variable frequency household electrical appliance according to claim 8, wherein said input voltage is less than said output voltage and said input current is greater than or equal to said pre- a maximum allowable current, outputting a first protection signal to the PFC control module to cause the PFC control module to control the PFC circuit to be turned off, and outputting a second protection signal to the motor controller to cause the A motor controller controls the motor to operate in a down frequency.
The method of claim 8, wherein the input voltage is less than the output voltage and the input current is less than the preset When the maximum allowable current, the PFC control module controls the PFC circuit to be turned on, and the motor controller controls the motor to operate normally according to a preset frequency.
The method of claim 10 or 11, wherein the first preset inductance is 0.5-1 mH, the first preset The frequency is 15-25KHz.