PFC circuit and control method thereof, storage medium and refrigeration equipment

Abstract

The invention discloses a PFC circuit and a control method thereof, a storage medium and refrigeration equipment, and the control method of the PFC circuit comprises the steps: determining a zero crossing point of an input AC power supply; and at the beginning of the zero crossing point, controlling a switch tube in the PFC circuit to be in a turn-off state, and after a first preset time, controlling the switch tube to be alternately turned on and turned off. Therefore, according to the method, when the zero crossing point of the alternating current power supply is detected, the switching tube in the PFC circuit is controlled to continue to be in the turn-off state for the first preset time, and after the first preset time, in order to ensure that the current is output along with the voltage, the current is controlled to reach the current peak value at a high speed, so that the frequency doubling fluctuation of the input alternating current power supply frequency in the output power of the PFC circuit is reduced; the frequency doubling component of the input alternating current power supply frequency in the ripple current existing on the bus electrolytic capacitor is reduced, so that the purposes of reducing the heating of the bus electrolytic capacitor and prolonging the service life of the bus electrolytic capacitor are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of refrigeration equipment, and in particular to a control method of a PFC (Power Factor Correction) circuit, a computer-readable storage medium, a PFC circuit and a refrigeration equipment. Background Art

[0002] The compressor in the variable frequency air conditioner is usually driven and controlled by an AC-DC-AC inverter. The AC power is controlled by a rectifier bridge and a power factor correction circuit (PFC) to output a DC voltage, and then a stable DC voltage is provided to the inverter through an electrolytic capacitor, and then the inverter output AC voltage is controlled to drive the compressor. The current on the grid side of the inverter is synchronized with the grid voltage under the control of the power factor correction circuit, which causes the input power of the inverter to fluctuate greatly at twice the grid voltage frequency, while the output power of the compressor remains basically constant, resulting in a ripple current of twice the grid voltage frequency on the bus electrolytic capacitor, which increases the heat of the electrolytic capacitor and reduces the service life of the electrolytic capacitor. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the first object of the present invention is to propose a control method for a PFC circuit, when the zero crossing point of the AC power supply is detected, the switch tube in the PFC circuit is controlled to be in an off state for a first preset time, and after the first preset time, in order to ensure that the current follows the voltage output, the current is controlled to reach the current peak at a faster speed, thereby reducing the double frequency fluctuation of the input AC power frequency in the output power of the PFC circuit, reducing the double frequency component of the input AC power frequency in the ripple current on the bus electrolytic capacitor, thereby achieving the purpose of reducing the heating of the bus electrolytic capacitor and extending the service life of the bus electrolytic capacitor.

[0004] A second object of the present invention is to provide a computer-readable storage medium.

[0005] The third objective of the present invention is to provide a PFC circuit.

[0006] A fourth objective of the present invention is to provide a refrigeration device.

[0007] To achieve the above-mentioned purpose, a first aspect of the present invention provides a method for controlling a PFC circuit, the method comprising: determining a zero-crossing point of an input AC power supply; at the beginning of the zero-crossing point, controlling a switch tube in the PFC circuit to be in an off state, and after a first preset time, controlling the switch tube to be alternately turned on and off.

[0008] According to the control method of the PFC circuit of the embodiment of the present invention, the zero-crossing point of the input AC power supply is first determined, and then at the beginning of the zero-crossing point, the switch tube in the PFC circuit is controlled to be in the off state, and after the first preset time, the switch tube is controlled to be alternately turned on and off. When the zero-crossing point of the AC power supply is detected, the method controls the switch tube in the PFC circuit to be in the off state for the first preset time, so that after the first preset time, in order to ensure that the PFC circuit achieves current following voltage output, it is necessary to make the current reach the peak value at a faster speed, thereby reducing the double frequency fluctuation of the input AC power frequency in the output power of the PFC circuit, and reducing the double frequency component of the input AC power frequency in the ripple current of the bus electrolytic capacitor, thereby achieving the purpose of reducing the heating of the bus electrolytic capacitor and extending the service life of the bus electrolytic capacitor.

[0009] In addition, the control method of the PFC circuit according to the above embodiment of the present invention may also have the following additional technical features:

[0010] According to one embodiment of the present invention, determining the zero-crossing point of the input AC power source includes: acquiring at least one of an input voltage and an input current of a PFC circuit; and determining the zero-crossing point according to at least one of the input voltage and the input current.

[0011] According to an embodiment of the present invention, after acquiring at least one of an input voltage and an input current of the PFC circuit, the control method of the PFC circuit further includes: determining a change cycle of the input AC power supply according to at least one of the input voltage and the input current; and determining a first preset time according to the change cycle.

[0012] According to one embodiment of the present invention, the first preset time is determined by the following formula:

[0013] t=T×K

[0014] Wherein, t represents the first preset time, T represents the change period, and K represents the preset coefficient.

[0015] According to an embodiment of the present invention, the preset coefficient is greater than 0 and less than 0.25.

[0016] According to an embodiment of the present invention, a PWM (Pulse Width Modulation) signal with adjustable duty cycle is used to control the switch tube to be alternately turned on and off.

[0017] According to an embodiment of the present invention, the first preset time is an integer multiple of a carrier cycle of the PWM signal.

[0018] To achieve the above object, a second aspect of the present invention provides a computer-readable storage medium on which a control program of a PFC circuit is stored. When the control program of the PFC circuit is executed by a processor, the control method of the PFC circuit is implemented.

[0019] According to the computer-readable storage medium of the embodiment of the present invention, the control method of the PFC circuit is implemented when the control program of the PFC circuit is executed by the processor. Based on the control method of the PFC circuit, when the zero crossing point of the AC power source is detected, the switch tube in the PFC circuit is controlled to be in the off state for a first preset time, so that after the first preset time, in order to ensure that the PFC circuit achieves current following voltage output, the current value of the control current reaches the peak value at a faster speed, thereby reducing the double frequency fluctuation of the input AC power frequency in the output power of the PFC circuit, reducing the double frequency component of the input AC power frequency in the ripple current of the bus electrolytic capacitor, thereby achieving the purpose of reducing the heat generation of the bus electrolytic capacitor and extending the service life of the bus electrolytic capacitor.

[0020] To achieve the above-mentioned purpose, a third aspect of the present invention proposes a PFC circuit, including a memory, a processor, and a control program of the PFC circuit stored in the memory and executable on the processor. When the processor executes the control program of the PFC circuit, the control method of the PFC circuit is implemented.

[0021] According to the PFC circuit of the embodiment of the present invention, when the processor executes the control program of the PFC circuit, the control method of the PFC circuit is implemented. Based on the control method of the PFC circuit in the past, when the zero crossing point of the AC power is detected, the switch tube in the PFC circuit is controlled to be in the off state for a first preset time, so that after the first preset time, in order to ensure that the PFC circuit achieves current following voltage output, the current is controlled to reach the current peak at a faster speed, thereby reducing the double frequency fluctuation of the input AC power frequency in the output power of the PFC circuit, and reducing the double frequency component of the input AC power frequency in the ripple current of the bus electrolytic capacitor, thereby achieving the purpose of reducing the heat generation of the bus electrolytic capacitor and extending the service life of the bus electrolytic capacitor.

[0022] To achieve the above-mentioned purpose, the fourth aspect of the present invention proposes a refrigeration device, including: a PFC circuit; a control unit, used to determine the zero-crossing point of the input AC power supply, and at the beginning of the zero-crossing point, control the switch tube in the PFC circuit to be in an off state, and after a first preset time, control the switch tube to be alternately turned on and off.

[0023] According to the refrigeration device of the embodiment of the present invention, the control unit determines the zero-crossing point of the input AC power supply, and at the beginning of the zero-crossing point, controls the switch tube in the PFC circuit to be in the off state, and after the first preset time, controls the switch tube to be alternately turned on and off. When the refrigeration device detects the zero-crossing point of the AC power supply, the switch tube in the PFC circuit is controlled to remain in the off state for the first preset time, so that after the first preset time, in order to ensure that the PFC circuit achieves current following voltage output, the current is controlled to reach the current peak at a faster speed, thereby reducing the double frequency fluctuation rate of the input AC power frequency in the output power of the PFC circuit, and reducing the double frequency component of the input AC power frequency in the ripple current of the bus electrolytic capacitor, thereby achieving the purpose of reducing the heat generation of the bus electrolytic capacitor and extending the service life of the bus electrolytic capacitor.

[0024] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a flow chart of a control method of a PFC circuit according to an embodiment of the present invention;

[0026] Figure 2 A connection diagram of a PFC circuit according to an embodiment of the present invention;

[0027] Figure 3 is a waveform diagram of an input voltage or input current and a control signal of a PFC circuit according to an embodiment of the present invention;

[0028] Figure 4 is a flow chart of a control method of a PFC circuit according to an embodiment of the present invention;

[0029] Figure 5 is a block diagram of a PFC circuit according to an embodiment of the present invention;

[0030] Figure 6 FIG. 4 is a block diagram of a refrigeration device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0032] The following describes a control method for a PFC circuit, a computer-readable storage medium, a PFC circuit, and a refrigeration device provided in embodiments of the present invention with reference to the accompanying drawings.

[0033] Figure 1 FIG. 4 is a flow chart of a control method of a PFC circuit according to an embodiment of the present invention.

[0034] Reference Figure 1 As shown, the control method of the PFC circuit in the embodiment of the present invention may include:

[0035] S1, determine the zero-crossing point of the input AC power;

[0036] S2, at the beginning of the zero crossing, the switch tube in the PFC circuit is controlled to be in the off state, and after a first preset time, the switch tube is controlled to be alternately turned on and off.

[0037] Take the application of PFC circuit in motor drive as an example, see Figure 2 As shown, the AC source AC, the rectifier bridge 10, the PFC circuit 20, and the inverter 30 are connected in sequence, wherein the rectifier bridge 10 is used to convert the AC power provided by the AC source AC into a DC power output, and the PFC circuit 20 receives the DC power output by the rectifier bridge 10 and performs power factor correction, mainly by controlling the waveform of the input current by controlling the on and off of the switch tube Q1, so that the input current is synchronized with the input voltage waveform to improve the power factor and reduce the harmonic content, thereby solving the electromagnetic interference (EMl) and electromagnetic compatibility (EMC) problems caused by the serious distortion of the current waveform caused by the capacitive load. The electrolytic capacitor EC1 is connected in parallel to the output end of the PFC circuit 20, and the DC signal output by the PFC circuit 20 is filtered by the electrolytic capacitor EC1, and the stable DC signal is sent to the inverter 30, and the inverter 30 converts the received DC power into a three-phase power output by opening and closing the internal IGBT (Insulated Gate Bipolar Transistor) to drive the motor 40 to run.

[0038] Among them, the PFC circuit 20 is composed of an inductor L1, a diode D1 and a switch tube Q1. The control unit 59 adjusts the current waveform by controlling the on and off of the switch tube Q1 to compensate for the phase difference between the current and voltage, thereby achieving the following effect of the input current on the input voltage.

[0039] The current provided by the alternating current source AC is synchronized with the voltage waveform under the control of the PFC circuit 20, that is, the current and voltage are in the same phase and frequency, which causes the output power of the inverter 30 to fluctuate greatly at twice the voltage frequency. Since a stable DC signal is provided to the inverter 30, the fluctuation of twice the voltage frequency is absorbed by the electrolytic capacitor EC1, resulting in a ripple current of twice the voltage frequency on the electrolytic capacitor EC1, which increases the heat generation of the electrolytic capacitor EC1 and reduces the service life of the electrolytic capacitor EC1. In order to reduce the heat generation of the electrolytic capacitor EC1, the present application proposes a control method for a PFC circuit, which is as follows:

[0040] During the operation of the PFC circuit 10, the zero-crossing point of the output AC power of the input AC power source AC is detected. When the zero-crossing point is determined to start, the control unit 50 continuously outputs a low level for a first preset time, so that the switch tube Q1 is in an off state during the first preset time, and the PFC circuit 20 is controlled not to work during the first preset time, which is equivalent to the current value of the input current being continuously 0 during the first preset time. When it is determined that the first preset time has ended, the control unit 50 controls the switch tube Q1 to be turned on and off according to a preset rule to achieve the output of the current following the voltage. Further, when the switch tube Q1 is controlled to be continuously maintained in the off state, the current is cut off. When the switch tube Q1 is turned on again, the switch tube Q1 is controlled with a larger duty cycle, thereby accelerating the growth rate of the current, so that the current reaches the current peak at a faster speed from 0 to ensure the current following the voltage. The continuous shutdown for the first preset time causes the current to be cut off, so that the current waveform remains in a straight line state for a period of time within the first preset time, so as to reduce the double frequency fluctuation of the input AC power frequency in the output power of the PFC circuit 10, and reduce the double frequency component of the input AC power frequency in the ripple current on the bus electrolytic capacitor EC1, thereby reducing the heat generated by the electrolytic capacitor EC1 and ensuring the service life of the electrolytic capacitor EC1.

[0041] In one embodiment of the present invention, determining the zero-crossing point of the input AC power source includes: acquiring at least one of an input voltage and an input current of a PFC circuit; and determining the zero-crossing point according to at least one of the input voltage and the input current.

[0042] Continue with Figure 2 For example, the waveform of the voltage or current output to the PFC circuit 20 through the rectifier bridge 10, that is, the waveform of the input voltage or input current of the PFC circuit 20, is as follows: Figure 3 This embodiment detects the zero-crossing point of the voltage or current output by the rectifier bridge 10 to the PFC circuit 20, thereby determining the zero-crossing point of the input alternating current power source AC.

[0043] For example, the zero-crossing point can be determined according to the output voltage of the PFC circuit 20. The input voltage of the PFC circuit 20 can be sampled and obtained by the voltage detection unit 70, and the input voltage sampled and obtained in real time can be sent to the control unit 50. After the control unit 50 performs analog-to-digital conversion on the input voltage, it is compared with the preset voltage value. When the sampled input voltage is less than or equal to the preset voltage value, the moment is determined to be the zero-crossing point of the AC power supply. When the zero-crossing point is determined according to the output current of the PFC circuit 20, the input current of the PFC circuit 20 can be sampled and obtained by the current detection unit 60 connected in series between the negative input terminal of the PFC circuit 20 and the negative output terminal of the rectifier bridge 10. After the control unit 50 performs analog-to-digital conversion on the sampled input current, it is compared with the preset current value. When it is determined that the sampled input current is less than or equal to the preset current value, the moment is determined to be the zero-crossing point of the input AC power supply.

[0044] Combination Figure 2 and Figure 3 After determining that the input AC power source crosses the zero point at time t2, the control unit 50 outputs a low-level control signal to the control end of the switch tube Q1 during the time period t2-t3, thereby controlling the switch tube Q1 to maintain the disconnected state during the time period t2-t3. The time difference between t3 and t2 is the first preset time.

[0045] In one embodiment of the present invention, after acquiring at least one of an input voltage and an input current of the PFC circuit, the control method of the PFC circuit further includes: determining a change cycle of the input AC power source according to at least one of the input voltage and the input current; and determining a first preset time according to the change cycle.

[0046] In one embodiment of the present invention, the first preset time is determined by the following formula:

[0047] t=T×K (1)

[0048] Wherein, t represents the first preset time, T represents the change period, and K represents the preset coefficient.

[0049] Specifically, taking the acquisition of the input voltage of the PFC circuit as an example, after the input voltage of the PFC circuit is acquired, the peak value and the zero-crossing point of the corresponding input voltage can be determined according to the input voltage, and the time interval between adjacent peak values ​​or the time interval between adjacent zero-crossing points of the input voltage is used as the variation period, and then the variation period is substituted into formula (1) to calculate and determine the first preset time.

[0050] It should be noted that when the input AC source is stable, the voltage and current waveforms of the rectifier output (i.e. the input voltage and input current of the PFC circuit) are as follows: Figure 3As shown, the change period of the input AC power can be determined by the time interval between adjacent peaks and / or the time interval between adjacent zero crossings of the waveform. Figure 3 Schematic diagrams of two adjacent waveforms of the input voltage are shown. It is determined that the input voltage reaches the voltage peak at time t1 and time t4, and is a zero-crossing point at time t2 and time t5. According to time t1 and time t4, the change period 1 (T1=t4-t2) can be determined, and according to time t2 and time t5, the change period 2 (T2=t5-t2) can be determined. Among them, the change period 1 can be used as the change period of the input AC power supply, and the change period 2 can also be used as the change period of the input AC power supply. Alternatively, the average value of the change period 1 and the change period 2 can be used as the change period of the input AC power supply, and there is no limitation here.

[0051] After determining the variation cycle of the AC power supply, the first preset time is further determined according to the variation cycle of the input AC power supply. Under the premise of ensuring the normal operation of the PFC circuit and the following effect of the current on the voltage, the fluctuation component of the current is reduced, so as to achieve the purpose of reducing the ripple current fluctuation of the electrolytic capacitor and reduce the heat generated by the electrolytic capacitor.

[0052] In one embodiment of the present invention, the preset coefficient is greater than 0 and less than 0.25.

[0053] Specifically, the duration of the continuous shutdown of the switch tube within the change cycle is determined by selecting a preset coefficient. It can be understood that after the switch tube in the PFC circuit is controlled to be turned off for the first preset time, in order to ensure that the PFC circuit realizes current following voltage output, after the switch tube is controlled to be turned on again, the current will reach the current peak at a faster speed, and the current peak is greater than the initial current peak before the switch tube is turned off for the first preset time. The longer the first preset time, the greater the current peak reached after the switch tube is turned on again. In order to avoid overcurrent, the value range of the preset coefficient is set to (0, 0.25) to ensure that while reducing the heat generation of the bus electrolytic capacitor and extending the service life of the bus electrolytic capacitor, the overcurrent phenomenon is avoided and the working stability of the PFC circuit is ensured. The preset coefficient can be set according to the actual situation, and generally the corresponding moment when the current amplitude rises to half of the amplitude is selected.

[0054] In one embodiment of the present invention, a PWM signal with adjustable duty cycle is used to control the switch tube to be alternately turned on and off.

[0055] Specifically, continue with Figure 2 For example, the control unit 50 controls the on or off of the switch tube Q1 by outputting a PWM signal as a control signal. Figure 2In the embodiment, an NPN transistor is used. When the control unit 50 sends a high level to the control end of the switch tube Q1, the switch tube Q1 is turned on. When the control end of the phase switch tube Q1 sends a low level, the switch tube Q1 is turned off.

[0056] In one embodiment of the present invention, the first preset time is an integer multiple of the carrier cycle of the PWM signal, so as to facilitate the generation of the PWM signal and ensure the smooth progress of the control process.

[0057] As a specific embodiment of the present invention, Figure 4 As shown, the control method of the PFC circuit in the embodiment of the present invention may include the following steps:

[0058] S401, obtaining an input voltage of a PFC circuit;

[0059] S402, determining the zero-crossing point of the input voltage, and taking the time interval between adjacent zero-crossing points as the change cycle of the input AC power supply;

[0060] S403, determining a first preset time according to the change cycle;

[0061] S404, when the PFC circuit is running, a PWM signal with an adjustable duty cycle is used to control the switch tube to be turned on and off;

[0062] S405, determining whether the zero-crossing point of the input AC power source has started. If yes, executing step S406; if no, executing step S404.

[0063] S406, controlling the switch tube in the PFC circuit to remain in the off state.

[0064] S407, determining whether the duration of the switch tube being in the off state reaches a first preset time. If yes, executing step S404; if no, executing step S406.

[0065] In summary, according to the control method of the PFC circuit of the embodiment of the present invention, the zero-crossing point of the input AC power supply is first determined, and then at the beginning of the zero-crossing point, the switch tube in the PFC circuit is controlled to be in the off state, and after the first preset time, the switch tube is controlled to be alternately turned on and off. When the zero-crossing point of the AC power supply is detected, the method controls the switch tube in the PFC circuit to be in the off state for the first preset time, so that after the first preset time, in order to ensure that the PFC circuit realizes the current following the voltage output, it is necessary to make the current reach the peak value at a faster speed, thereby reducing the output power of the PFC circuit, reducing the double frequency fluctuation of the input AC power frequency in the output power of the PFC circuit, and reducing the double frequency component of the input AC power frequency in the ripple current on the bus electrolytic capacitor, thereby achieving the purpose of reducing the heating of the bus electrolytic capacitor and extending the service life of the bus electrolytic capacitor.

[0066] Corresponding to the above embodiment, the present invention also proposes a computer-readable storage medium.

[0067] The computer-readable storage medium of the embodiment of the present invention stores a control program of a PFC circuit, and the control program of the PFC circuit implements the above-mentioned control method of the PFC circuit when executed by a processor.

[0068] According to the computer-readable storage medium of the embodiment of the present invention, the control method of the PFC circuit is implemented when the control program of the PFC circuit is executed by the processor. Based on the control method of the PFC circuit, when the zero crossing point of the AC power source is detected, the switch tube in the PFC circuit is controlled to be in the off state for a first preset time, thereby reducing the output power of the PFC circuit, reducing the double frequency fluctuation of the input AC power frequency in the output power of the PFC circuit, and reducing the double frequency component of the input AC power frequency in the ripple current on the bus electrolytic capacitor, thereby achieving the purpose of reducing the heat generation of the bus electrolytic capacitor and extending the service life of the bus electrolytic capacitor.

[0069] Corresponding to the above embodiment, the present invention further proposes a PFC circuit.

[0070] Reference Figure 5 As shown, the PFC circuit 20 of the embodiment of the present invention includes a memory 21, a processor 22, and a control program of the PFC circuit stored in the memory 21 and executable on the processor 22. When the processor 22 executes the control program of the PFC circuit, the control method of the PFC circuit described above is implemented.

[0071] According to the PFC circuit of the embodiment of the present invention, when the processor executes the control program of the PFC circuit, the control method of the PFC circuit is implemented. Based on the control method of the PFC circuit in the past, when the zero crossing point of the AC power is detected, the switch tube in the PFC circuit is controlled to be in the off state for a first preset time, thereby reducing the output power of the PFC circuit, reducing the double frequency fluctuation of the input AC power frequency in the output power of the PFC circuit, and reducing the double frequency component of the input AC power frequency in the ripple current on the bus electrolytic capacitor, thereby achieving the purpose of reducing the heat generation of the bus electrolytic capacitor and extending the service life of the bus electrolytic capacitor.

[0072] Corresponding to the above embodiment, the present invention also proposes a refrigeration device.

[0073] like Figure 6 As shown, the refrigeration device 100 of the embodiment of the present invention includes: a PFC circuit 20 and a control unit 50. The control unit 50 is used to determine the zero-crossing point of the input AC power supply, and at the beginning of the zero-crossing point, control the switch tube in the PFC circuit 20 to be in the off state, and after the first preset time, control the switch tube to be alternately turned on and off.

[0074] According to the refrigeration device of the embodiment of the present invention, the control unit determines the zero-crossing point of the input AC power supply, and at the beginning of the zero-crossing point, controls the switch tube in the PFC circuit to be in the off state, and after the first preset time, controls the switch tube to be alternately turned on and off. When the refrigeration device detects the zero-crossing point of the AC power supply, the switch tube in the PFC circuit is controlled to remain in the off state for the first preset time, so that after the first preset time, in order to ensure that the PFC circuit achieves current following voltage output, it is necessary to make the current reach the peak value at a faster speed, thereby reducing the output power of the PFC circuit, reducing the double frequency fluctuation of the input AC power frequency in the output power of the PFC circuit, and reducing the double frequency component of the input AC power frequency in the ripple current on the bus electrolytic capacitor, thereby achieving the purpose of reducing the heat generation of the bus electrolytic capacitor and extending the service life of the bus electrolytic capacitor.

[0075] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0076] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0077] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0078] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0079] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0080] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A control method for a PFC circuit, characterized in that: The method comprises: Determine the zero-crossing point of the input AC power; At the beginning of the zero crossing, the switch tube in the PFC circuit is controlled to be in an off state, and after a first preset time, the switch tube is controlled to be alternately turned on and off.

2. The method according to claim 1, characterized in that Determine the zero-crossing point of the input AC power, including: Acquire at least one of an input voltage and an input current of the PFC circuit; The zero-crossing point is determined according to at least one of the input voltage and the input current.

3. The method according to claim 2, characterized in that After obtaining at least one of an input voltage and an input current of the PFC circuit, the method further includes: determining a variation period of the input AC power source according to at least one of the input voltage and the input current; The first preset time is determined according to the change cycle.

4. The method according to claim 2, characterized in that: The first preset time is determined by the following formula: t=T×K Wherein, t represents the first preset time, T represents the change period of the input AC power supply, and K represents a preset coefficient.

5. The method according to claim 4, characterized in that The preset coefficient is greater than 0 and less than 0.

25.

6. The method according to any one of claims 1 to 5, characterized in that A PWM signal with adjustable duty cycle is used to control the switch tube to be alternately turned on and off.

7. The method according to claim 6, characterized in that The first preset time is an integer multiple of a carrier period of the PWM signal.

8. A computer-readable storage medium, characterized in that: A control program of a PFC circuit is stored thereon, and when the control program of the PFC circuit is executed by a processor, a control method of a PFC circuit according to any one of claims 1 to 7 is implemented.

9. A PFC circuit, characterized in that: The invention comprises a memory, a processor and a control program of a PFC circuit which is stored in the memory and can be run on the processor. When the processor executes the control program of the PFC circuit, the control method of the PFC circuit according to any one of claims 1 to 7 is implemented.

10. A refrigeration device, characterized in that: include: PFC circuit; The control unit is used to determine the zero-crossing point of the input AC power supply, and at the beginning of the zero-crossing point, control the switch tube in the PFC circuit to be in an off state, and after a first preset time, control the switch tube to be alternately turned on and off.

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