Motor driving circuit and control method therefor, motor controller, and household appliance

Abstract

A motor driving circuit and a control method therefor, a motor controller, and a household appliance. The motor driving circuit comprises a PFC unit, a bus capacitor, and an inverter; the bus capacitor is arranged at an output end of the PFC unit; and the inverter is configured to drive a motor to work on the basis of a bus voltage on the bus capacitor. The method comprises: synchronously controlling a PFC unit and an inverter, such that the PFC unit works in a charging state when the inverter works in a follow current state, and the PFC unit works in a discharging state when the inverter works in a driving state.

Description

Motor drive circuit and control method thereof, motor controller, and household appliance

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims priority to Chinese patent application No. 2023108039013, filed on June 30, 2023, entitled “Motor drive circuit and control method thereof, motor controller, and household appliance,” the entire contents of which are incorporated by reference into this disclosure. Technical Field

[0003] The present disclosure relates to the field of motor control technology, and in particular to a motor drive circuit and a control method thereof, a motor controller, and a household appliance. Background Art

[0004] Currently, the drive circuit for an air conditioner outdoor unit typically utilizes a rectifier bridge, a boost rectifier, and a compressor inverter circuit. The PFC (Power Factor Correction) drive and compressor drive in related technologies are unrelated, so the energy provided by the PFC and the energy required by the compressor inverter are independent. This independent energy control requires charging and discharging the busbar capacitor, increasing capacitor ripple and requiring larger capacitors.

[0005] Public content

[0006] The present disclosure aims to at least partially address one of the technical issues in the related art. To this end, a first object of the present disclosure is to provide a control method for a motor drive circuit that synchronizes the PFC unit and the inverter to ensure that the operating state of the PFC unit matches the operating state of the inverter, thereby reducing energy loss in the bus capacitor and thereby reducing capacitor ripple, thereby enabling the selection of smaller capacitors.

[0007] A second object of the present disclosure is to provide a computer-readable storage medium.

[0008] The third objective of the present disclosure is to provide a motor controller.

[0009] A fourth objective of the present disclosure is to provide a motor drive circuit.

[0010] A fifth objective of the present disclosure is to provide a household appliance.

[0011] To achieve the above-mentioned objectives, according to an embodiment of the first aspect of the present disclosure, a control method for a motor drive circuit is proposed. The motor drive circuit includes a PFC unit, a bus capacitor and an inverter. The bus capacitor is arranged at the output end of the PFC unit. The inverter is configured to drive the motor to operate according to the bus voltage on the bus capacitor. The method includes: synchronously controlling the PFC unit and the inverter so that when the inverter operates in a freewheeling state, the PFC unit operates in a charging state; when the inverter operates in a driving state, the PFC unit operates in a discharging state.

[0012] According to the control method of the motor drive circuit of the embodiment of the present disclosure, the PFC unit and the inverter are synchronously controlled so that when the inverter operates in the freewheeling state, the PFC unit operates in the charging state; when the inverter operates in the driving state, the PFC unit operates in the discharging state. When the inverter is in the freewheeling state, it does not obtain energy from the capacitor. Therefore, the PFC unit is controlled to operate in the charging state; when the inverter is in the driving state, it obtains energy from the capacitor. Therefore, the PFC unit is controlled to directly discharge the inverter, so that the operating state of the PFC unit matches the operating state of the inverter, reducing the energy loss on the bus capacitor, thereby reducing the capacitor ripple. In this way, a capacitor with a smaller capacity can be selected, thereby reducing the cost of the motor drive circuit.

[0013] According to one embodiment of the present disclosure, synchronous control of the PFC unit and the inverter includes: controlling the upper bridge switches in the inverter to be turned on and the lower bridge switches to be turned off simultaneously, and simultaneously controlling the switches in the PFC unit to be turned on, so that the inverter operates in a freewheeling state while the PFC unit operates in a charging state.

[0014] According to one embodiment of the present disclosure, synchronous control of the PFC unit and the inverter includes: controlling the upper bridge switches in the inverter to be turned off and the lower bridge switches to be turned on simultaneously, and simultaneously controlling the switches in the PFC unit to be turned on, so that the inverter operates in a freewheeling state while the PFC unit operates in a charging state.

[0015] According to one embodiment of the present disclosure, synchronous control of a PFC unit and an inverter includes: controlling one or two upper bridge switches in the inverter to turn on and the remaining upper bridge switches to turn off, controlling the lower bridge switches corresponding to the turned-on upper bridge switches in the inverter to turn off and the lower bridge switches corresponding to the turned-off upper bridge switches to turn on, and simultaneously controlling the switches in the PFC unit to turn off, so that the inverter operates in a driving state while the PFC unit operates in a discharging state.

[0016] According to one embodiment of the present disclosure, when controlling the switch tube in the PFC unit, the method further includes: determining an ideal duty cycle and a required duty cycle of the switch tube; and determining a target duty cycle of the switch tube based on the relationship between the ideal duty cycle and the required duty cycle.

[0017] According to one embodiment of the present disclosure, a target duty cycle of the switching tube is determined based on the relationship between the ideal duty cycle and the required duty cycle, including: when the required duty cycle is less than the ideal duty cycle, increasing the required duty cycle, and when the switching tube current of the PFC unit is greater than or equal to a preset current threshold, using the current duty cycle as the target duty cycle.

[0018] According to one embodiment of the present disclosure, determining the target duty cycle of the switching tube based on the relationship between the ideal duty cycle and the required duty cycle also includes: when the required duty cycle is increased, if the switching tube current of the PFC unit is less than a preset current threshold, then when the current duty cycle is greater than or equal to the ideal duty cycle, using the ideal duty cycle as the target duty cycle.

[0019] According to an embodiment of the present disclosure, determining the target duty cycle of the switch tube based on the relationship between the ideal duty cycle and the required duty cycle also includes: when the required duty cycle is greater than or equal to the ideal duty cycle, using the ideal duty cycle as the target duty cycle.

[0020] To achieve the above objectives, according to the second embodiment of the present disclosure, a computer-readable storage medium is proposed, on which a control program for a motor drive circuit is stored. When the program is executed by a processor, the control method for the motor drive circuit of any of the aforementioned embodiments is implemented.

[0021] According to the computer-readable storage medium of the embodiment of the present disclosure, by executing a computer program of the control method of the motor drive circuit, the PFC unit and the inverter are synchronously controlled so that the operating state of the PFC unit matches the operating state of the inverter, thereby reducing energy loss on the bus capacitor, thereby reducing capacitor ripple, and further allowing the selection of capacitors with smaller capacitance.

[0022] To achieve the above-mentioned purpose, according to an embodiment of the third aspect of the present disclosure, a motor controller is proposed, comprising: a memory, a processor, and a control program for a motor drive circuit stored in the memory and runnable on the processor. When the processor executes the program, the control method for the motor drive circuit of any of the aforementioned embodiments is implemented.

[0023] According to the motor controller of the embodiment of the present disclosure, a computer program of the control method of the motor drive circuit is executed by a processor, and the operating state of the PFC unit and the inverter are synchronously controlled to match the operating state of the PFC unit, thereby reducing the energy loss on the bus capacitor, thereby reducing the capacitor ripple, and further allowing the selection of capacitors with smaller capacity.

[0024] To achieve the above-mentioned objectives, according to an embodiment of the fourth aspect of the present disclosure, a motor drive circuit is proposed, comprising: a PFC unit, a bus capacitor and an inverter, wherein the bus capacitor is arranged at the output end of the PFC unit, and the inverter is configured to drive the motor to operate according to the bus voltage on the bus capacitor; a controller is configured to synchronously control the PFC unit and the inverter so that when the inverter operates in a freewheeling state, the PFC unit operates in a charging state; and when the inverter operates in a driving state, the PFC unit operates in a discharging state.

[0025] According to the motor drive circuit of the embodiment of the present disclosure, the controller synchronously controls the PFC unit and the inverter so that when the inverter operates in the freewheeling state, the PFC unit operates in the charging state; when the inverter operates in the driving state, the PFC unit operates in the discharging state. When the inverter is in the freewheeling state, it does not obtain energy from the capacitor, so the PFC unit is controlled to operate in the charging state; when the inverter is in the driving state, it obtains energy from the capacitor, so the PFC unit is controlled to directly discharge the inverter, so that the operating state of the PFC unit matches the operating state of the inverter, reducing the energy loss on the bus capacitor, thereby reducing the capacitor ripple, so that a capacitor with a smaller capacity can be selected, thereby reducing the cost of the motor drive circuit.

[0026] To achieve the above-mentioned objective, according to a fifth aspect of the present disclosure, a household appliance is proposed, comprising the aforementioned motor drive circuit.

[0027] According to the household appliance of the embodiment of the present disclosure, by adopting the above-mentioned motor drive circuit, the PFC unit and the inverter are synchronously controlled so that the working state of the PFC unit matches the working state of the inverter, thereby reducing the energy loss on the bus capacitor, thereby reducing the capacitor ripple, and further allowing the selection of a capacitor with a smaller capacity.

[0028] Additional aspects and advantages of the present disclosure will be given in part in the description below and in part will be obvious from the description below, or will be learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG1 is a circuit diagram of a motor drive according to one embodiment of the present disclosure;

[0030] FIG2 is a waveform diagram of a driving signal of an inverter according to an embodiment of the present disclosure;

[0031] 3 to 6 are schematic diagrams of current flow of an inverter in different working states according to an embodiment of the present disclosure;

[0032] FIG7 is a flow chart of a method for controlling a motor drive circuit according to an embodiment of the present disclosure;

[0033] FIG8 is a schematic diagram of current flow when the inverter is in a (0.0.0) working state and the PFC unit is in a charging state according to one embodiment of the present disclosure;

[0034] FIG9 is a schematic diagram of current flow when the inverter is in the (1.0.0) working state and the PFC unit is in the discharging state according to one embodiment of the present disclosure;

[0035] FIG10 is a schematic diagram of current flow when the inverter is in the (1.1.0) working state and the PFC unit is in the discharging state according to one embodiment of the present disclosure;

[0036] FIG11 is a schematic diagram of current flow when the inverter is in the (1.1.1) working state and the PFC unit is in the charging state according to one embodiment of the present disclosure;

[0037] FIG12 is a waveform diagram of a driving signal of an inverter according to another embodiment of the present disclosure;

[0038] FIG13 is a waveform diagram of an ideal duty cycle and a driving signal of an inverter according to one embodiment of the present disclosure;

[0039] FIG14 is a waveform diagram of an ideal duty cycle and a required duty cycle according to one embodiment of the present disclosure;

[0040] FIG15 is a waveform diagram of an ideal duty cycle and a required duty cycle according to another embodiment of the present disclosure;

[0041] FIG16 is a flow chart of a method for determining a target duty cycle according to an embodiment of the present disclosure;

[0042] FIG17 is a system diagram of a motor controller according to one embodiment of the present disclosure;

[0043] FIG18 is a system diagram of a household appliance according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0044] The following describes in detail embodiments of the present disclosure, 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 disclosure, and should not be construed as limiting the present disclosure.

[0045] It should be noted that the present disclosure is based on the inventor's understanding and research of the following issues:

[0046] As shown in FIG1 , the motor drive circuit includes a PFC unit 10 , a bus capacitor C1 and an inverter 20 . The bus capacitor C1 is provided at the output end of the PFC unit 10 . The inverter 20 is configured to drive the motor M to operate according to the bus voltage on the bus capacitor C1 .

[0047] The PFC unit 10 includes a first inductor L1, a seventh diode D7, and a seventh switch Q7. One end of the first inductor L1 is connected to the positive electrode of a DC power source, the other end of the first inductor L1 is connected to the anode of the seventh diode D7, and the cathode of the seventh diode D7 is connected to one end of a bus capacitor C1. A first end of the seventh switch Q7 is connected to the other end of the first inductor L1 and the anode of the seventh diode D7, respectively. A second end of the seventh switch Q7 is connected to the other end of the bus capacitor C1 and is connected to the negative electrode of the DC power source. When the seventh switch Q7 is on, the PFC unit 10 operates in a charging state. When the seventh switch Q7 is off, the PFC unit 10 operates in a discharging state.

[0048] Furthermore, the motor drive circuit also includes a rectifier unit 30, which is configured to convert the AC power supply AC into a DC power supply and provide the DC power supply to the PFC unit 10. The rectifier unit 30 includes first to fourth diodes D1 to D4. The anode of the first diode D1 is adapted to be connected to the positive electrode of the AC power supply AC. The cathode of the first diode D1 is respectively connected to the cathode of the second diode D2 and one end of the first inductor L1. The anode of the second diode D2 is adapted to be connected to the negative electrode of the AC power supply AC. The cathode of the third diode D3 is connected to the anode of the first diode D1. The anode of the third diode D3 is respectively connected to the anode of the fourth diode D4 and the second end of the seventh switch tube Q7. The cathode of the fourth diode D4 is connected to the anode of the second diode D2.

[0049] Inverter 20 includes six switches, namely, first switch Q1 to sixth switch Q6. First switch Q1 and second switch Q2 form the first arm of inverter 20, third switch Q3 and fourth switch Q4 form the second arm of inverter 20, and fifth switch Q5 and sixth switch Q6 form the third arm of inverter 20. The upper bridge switches (Q1, Q3, Q5) and lower bridge switches (Q2, Q4, Q6) of each arm are complementary. That is, when the upper bridge switches (Q1, Q3, Q5) are on, the lower bridge switches (Q2, Q4, Q6) are off, and when the upper bridge switches (Q1, Q3, Q5) are off, the lower bridge switches (Q2, Q4, Q6) are on. Therefore, as long as the driving waveforms of the upper bridge switches (Q1, Q3, Q5) are known, the driving waveforms of the lower bridge switches (Q2, Q4, Q6) can be derived. When the driving signal of the switch tube is at a high level, the switch tube is turned on, which is recorded as "1"; when the driving signal of the switch tube is at a low level, the switch tube is turned off, which is recorded as "0". As shown in Figure 2, taking the motor drive in sector I as an example, the inverter 20 will have four working states, namely (0.0.0), (1.0.0), (1.1.0) and (1.1.1). When the inverter 20 operates in the (0.0.0) state, the current flow in the inverter 20 is shown in Figure 3; when the inverter 20 operates in the (1.0.0) state, the current flow in the inverter 20 is shown in Figure 4; when the inverter 20 operates in the (1.1.0) state, the current flow in the inverter 20 is shown in Figure 5; when the inverter 20 operates in the (1.1.1) state, the current flow in the inverter 20 is shown in Figure 6. When the inverter 20 operates in the (0.0.0) and (1.1.1) states, the inverter 20 is in the freewheeling state, and the motor M does not obtain energy from the bus capacitor C1. When the inverter 20 operates in the (1.0.0) and (1.1.0) states, the inverter 20 is in the driving state, and the motor M obtains energy from the capacitor.

[0050] In related art, the PFC unit 10 and inverter 20 are controlled separately. When the PFC unit 10 is charging, if the inverter 20 is in the driving state, the bus capacitor C1 needs to discharge. When the PFC unit 10 is discharging, if the inverter 20 is in the freewheeling state, the bus capacitor C1 needs to charge, which increases the capacitor ripple. Therefore, when designing the circuit, a larger capacitor is required.

[0051] Based on this, the embodiments of the present disclosure provide a motor drive circuit and its control method, a motor controller, a household appliance, and a storage medium. By adopting the above-mentioned motor drive circuit and synchronously controlling the PFC unit and the inverter, the working state of the PFC unit and the working state of the inverter are matched, thereby reducing the energy loss on the bus capacitor, thereby reducing the capacitor ripple, and further allowing the selection of capacitors with smaller capacity.

[0052] The following describes a motor drive circuit and control method thereof, a motor controller, a home appliance, and a storage medium according to embodiments of the present disclosure with reference to the accompanying drawings.

[0053] As shown in FIG1 , the motor drive circuit includes a PFC unit 10 , a bus capacitor C1 and an inverter 20 . The bus capacitor C1 is provided at the output end of the PFC unit 10 . The inverter 20 is configured to drive the motor M to operate according to the bus voltage on the bus capacitor C1 .

[0054] FIG7 is a flow chart of a method for controlling a motor drive circuit according to an embodiment of the present disclosure. As shown in FIG7 , the method for controlling a motor drive circuit includes the following steps:

[0055] S101, synchronously control the PFC unit and the inverter to make

[0056] When the inverter is working in the freewheeling state, the PFC unit is working in the charging state;

[0057] When the inverter operates in the driving state, the PFC unit operates in the discharging state.

[0058] Specifically, as shown in Figures 8 to 11, Figures 8 and 11 illustrate the current flow when the inverter 20 operates in the freewheeling state and the PFC operates in the charging state. When the inverter 20 operates in the freewheeling state, the bus capacitor C1 is not required to provide power. Therefore, the PFC unit 10 is controlled to operate in the charging state so that energy on the bus capacitor C1 is not lost. Figures 9 and 10 illustrate the current flow when the inverter 20 operates in the driving state and the PFC unit 10 operates in the discharging state. When the inverter 20 operates in the driving state, the bus capacitor C1 is required to provide power. Therefore, the PFC unit 10 is controlled to operate in the discharging state so that the DC power supply and the PFC unit 10 can directly power the motor M. In this way, the electrical energy of the motor M can be obtained from the DC power supply, the PFC unit 10, and the bus capacitor C1, reducing energy loss on the bus capacitor C1.

[0059] In the above embodiment, the operating state of the PFC unit is matched with the operating state of the inverter, so that when the inverter is in the freewheeling state, the PFC unit operates in the charging state, and when the inverter is in the driving state, the PFC unit operates in the discharging state. This reduces the energy loss of the bus capacitor and thus reduces the capacitor ripple. In this way, when designing the circuit, a capacitor with a smaller capacity can be selected, thereby reducing the circuit cost.

[0060] In some embodiments, as shown in FIG8 , the PFC unit 10 and the inverter 20 are synchronously controlled, including: controlling the upper bridge switches (Q1, Q3, Q5) in the inverter 20 to be turned on simultaneously and the lower bridge switches (Q2, Q4, Q6) to be turned off simultaneously, and simultaneously controlling the switch Q7 in the PFC unit 10 to be turned on, so that the inverter 20 operates in a freewheeling state while the PFC unit 10 operates in a charging state.

[0061] Specifically, when the upper-bridge switches (Q1, Q3, and Q5) of inverter 20 are simultaneously turned on and the lower-bridge switches (Q2, Q4, and Q6) are simultaneously turned off, inverter 20 operates in the (0.0.0) state and the freewheeling state. When switch Q7 of PFC unit 10 is turned on, the DC power supply charges the first inductor L1 of PFC unit 10, and PFC unit 10 operates in the charging state.

[0062] In some embodiments, as shown in FIG11 , the PFC unit 10 and the inverter 20 are synchronously controlled, including: controlling the upper bridge switches (Q1, Q3, Q5) in the inverter 20 to be turned off simultaneously and the lower bridge switches (Q2, Q4, Q6) to be turned on simultaneously, and simultaneously controlling the switch Q7 in the PFC unit 10 to be turned on, so that the inverter 20 operates in a freewheeling state while the PFC unit 10 operates in a charging state.

[0063] That is, when the upper-bridge switches (Q1, Q3, Q5) in inverter 20 are simultaneously turned off and the lower-bridge switches (Q2, Q4, Q6) are simultaneously turned on, inverter 20 operates in state (1.1.1), meaning it operates in the freewheeling state. When switch Q7 in PFC unit 10 is turned on, the DC power supply charges first inductor L1 in PFC unit 10, and PFC unit 10 operates in the charging state.

[0064] In some embodiments, as shown in FIG9 and FIG10 , the PFC unit 10 and the inverter 20 are synchronously controlled, including: controlling one or two upper bridge switches in the inverter 20 to turn on and the remaining upper bridge switches to turn off, controlling the lower bridge switches corresponding to the turned-on upper bridge switches in the inverter 20 to turn off and the lower bridge switches corresponding to the turned-off upper bridge switches to turn on, and simultaneously controlling the switch Q7 in the PFC unit 10 to turn off, so that the inverter 20 operates in a driving state while the PFC unit 10 operates in a discharging state.

[0065] Specifically, the inverter 20 has a total of 8 working states, among which the (0.0.0) and (1.1.1) states are freewheeling states, and the remaining 6 working states are driving states. Therefore, by controlling one or two upper bridge switches in the inverter 20 to turn on and the remaining upper bridge switches to turn off, and controlling the lower bridge switches corresponding to the turned-on upper bridge switches in the inverter 20 to turn off and the lower bridge switches corresponding to the turned-off upper bridge switches to turn on, the inverter 20 operates in the remaining working states, and at the same time controls the switch Q7 in the PFC unit 10 to turn off, so that the DC power supply and the first inductor L1 in the PFC unit 10 can directly power the motor M, and the motor M obtains electrical energy from the DC power supply, the first inductor L1 in the PFC unit 10, and the bus capacitor C1, thereby reducing the loss of the bus capacitor C1.

[0066] For example, Figure 9 shows the current flow when the inverter 20 operates in the (1.0.0) state and the PFC unit 10 operates in the discharge state, and Figure 10 shows the current flow when the inverter 20 operates in the (1.1.0) state and the PFC unit 10 operates in the discharge state. The motor M obtains electrical energy from the DC power supply, the first inductor L1 in the PFC unit 10, and the bus capacitor C1, thereby reducing the loss of the bus capacitor C1.

[0067] It should be noted that, in actual applications, the waveform of the driving signal of the inverter 20 is not limited to the waveform shown in FIG. 2 , and may also be other waveforms.

[0068] Taking the waveform shown in Figure 12 as an example, when the inverter 20 is controlled to operate in the (0.0.0) and (1.1.1) states, the switch tube of the PFC unit 10 is controlled to be turned on; when the inverter 20 is controlled to operate in the (1.0.0) and (1.0.1) states, the switch tube of the PFC unit 10 is controlled to be turned off.

[0069] In some embodiments, when controlling the switch tube in the PFC unit, the method further includes: determining an ideal duty cycle and a required duty cycle of the switch tube; and determining a target duty cycle of the switch tube based on a relationship between the ideal duty cycle and the required duty cycle.

[0070] Specifically, the ideal duty cycle of the switch tube of the PFC unit is determined according to the drive signal of the inverter. As shown in FIG13 , t1-t6 is a control cycle T of the inverter. m , t1, t2 and t3 are a control cycle T of the PFC unit pfc , t4, t5 and t6 are the next control cycle T of the PFC unit pfc , so in ideal conditions, the control period of the PFC unit is T pfc is the inverter control period T mHalf the carrier frequency of the PFC unit, meaning the carrier frequency of the inverter is twice the carrier frequency of the inverter. The required duty cycle is determined based on the bus voltage, bus voltage reference value, and switch current. This waveform may differ from the ideal duty cycle. Therefore, the target duty cycle of the switch needs to be determined based on the relationship between the ideal and required duty cycles.

[0071] In some embodiments, as shown in FIG14 , a target duty cycle of the switch tube is determined based on a relationship between an ideal duty cycle and a demand duty cycle, including: when the demand duty cycle is less than the ideal duty cycle, increasing the demand duty cycle; and when the switch tube current of the PFC unit is greater than or equal to a preset current threshold, using the current duty cycle as the target duty cycle.

[0072] It can be understood that the demand duty cycle is less than the ideal duty cycle, which usually occurs at the voltage peak of the AC power supply. If the ideal duty cycle is used to control the switch tube of the PFC unit, the switch tube current may exceed the preset current threshold. Therefore, it is necessary to gradually increase the demand duty cycle until the switch tube current corresponding to the increased demand duty cycle is greater than or equal to the preset current threshold, and the current duty cycle is used as the target duty cycle.

[0073] Furthermore, in some embodiments, the target duty cycle of the switching tube is determined based on the relationship between the ideal duty cycle and the required duty cycle, and the method further includes: when the required duty cycle is increased, if the switching tube current of the PFC unit is less than a preset current threshold, then when the current duty cycle is greater than or equal to the ideal duty cycle, the ideal duty cycle is used as the target duty cycle.

[0074] That is to say, if the current duty cycle is greater than the ideal duty cycle, and the switch tube current corresponding to the current duty cycle is less than the preset current threshold, the switch tube current corresponding to the ideal duty cycle will not exceed the preset current threshold. Therefore, the ideal duty cycle can be directly used as the target duty cycle.

[0075] In some embodiments, as shown in FIG14 , determining the target duty cycle of the switch tube based on the relationship between the ideal duty cycle and the required duty cycle also includes: when the required duty cycle is greater than or equal to the ideal duty cycle, using the ideal duty cycle as the target duty cycle.

[0076] It can be understood that the demand duty cycle is greater than or equal to the ideal duty cycle, which usually occurs at the zero crossing point of the AC power supply. If the demand duty cycle is greater than or equal to the ideal duty cycle, the switching tube current corresponding to the ideal duty cycle will not exceed the preset current threshold. Therefore, the ideal duty cycle can be directly used as the target duty cycle.

[0077] In an optional embodiment, as shown in FIG15 , when there is a difference between the ideal duty cycle and the required duty cycle, the carrier frequency of the PFC unit can be increased so that the carrier frequency of the PFC unit is greater than twice the carrier frequency of the inverter. The increased carrier frequency of the PFC unit is the target duty cycle. When the required duty cycle is less than the ideal duty cycle, the target duty cycle is bounded by the high-level phase of the ideal duty cycle. That is, when the ideal duty cycle changes from a low level to a high level, the target duty cycle changes from a low level to a high level; when the ideal duty cycle changes from a high level to a low level, the target duty cycle changes from a high level to a low level; and when the ideal duty cycle is low, the target duty cycle is also low. Furthermore, the duty cycle area of ​​the target duty cycle is the same as the duty cycle area of ​​the required duty cycle. When the demand duty cycle is greater than or equal to the ideal duty cycle, the target duty cycle uses the high level stage of the demand duty cycle as the boundary, that is, when the demand duty cycle changes from a low level to a high level, the target duty cycle changes from a low level to a high level, and when the demand duty cycle changes from a high level to a low level, the target duty cycle changes from a high level to a low level. When the demand duty cycle is low, the target duty cycle is also low. Moreover, the duty cycle area of ​​the target duty cycle is the same as the duty cycle area of ​​the ideal duty cycle.

[0078] The technical solution of the present disclosure is further described in detail below in conjunction with specific implementation methods:

[0079] As shown in FIG16 , the method for determining the target duty cycle of the switch tube includes the following steps:

[0080] S201, determining an ideal duty cycle according to a driving signal of an inverter, and determining a required duty cycle according to a bus voltage, a bus voltage reference value, and a switch tube current.

[0081] S202 : Compare the ideal duty cycle with the required duty cycle.

[0082] S203: If the required duty cycle is greater than or equal to the ideal duty cycle, execute step S204.

[0083] S204: Taking the ideal duty cycle as the target duty cycle.

[0084] S205: If the required duty cycle is less than the ideal duty cycle, execute step S206.

[0085] S206: Increase the required duty cycle and detect the switch current of the PFC unit.

[0086] S207, determine whether the switch tube current is greater than or equal to the preset current threshold. If the switch tube current is greater than or equal to the preset current threshold, execute step S208; if the switch tube current is less than the preset current threshold, execute step S209.

[0087] S208: Taking the current duty cycle as the target duty cycle.

[0088] S209, determining whether the current duty cycle reaches the ideal duty cycle. If the current duty cycle reaches the ideal duty cycle, executing step S210; if the current duty cycle does not reach the ideal duty cycle, returning to step S206.

[0089] S210: Taking the ideal duty cycle as the target duty cycle.

[0090] In the above embodiment, if the required duty cycle is greater than or equal to the ideal duty cycle, the switch tube current corresponding to the ideal duty cycle will not exceed the preset current threshold, and the ideal duty cycle can be directly used as the target duty cycle; when the required duty cycle is less than the ideal duty cycle, if the switch tube current corresponding to the ideal duty cycle will exceed the preset current threshold, the required duty cycle needs to be increased to obtain the target duty cycle. If the switch tube current corresponding to the ideal duty cycle will not exceed the preset current threshold, the ideal duty cycle can be used as the target duty cycle.

[0091] In summary, according to the control method of the motor drive circuit of the embodiment of the present disclosure, the PFC unit and the inverter are synchronously controlled so that when the inverter operates in the freewheeling state, the PFC unit operates in the charging state; when the inverter operates in the driving state, the PFC unit operates in the discharging state. When the inverter is in the freewheeling state, it does not obtain energy from the capacitor. Therefore, the PFC unit is controlled to operate in the charging state; when the inverter is in the driving state, it obtains energy from the capacitor. Therefore, the PFC unit is controlled to discharge directly to the inverter, so that the operating state of the PFC unit matches the operating state of the inverter, reducing the energy loss on the bus capacitor, thereby reducing the capacitor ripple. In this way, a capacitor with a smaller capacity can be selected, thereby reducing the cost of the motor drive circuit.

[0092] Corresponding to the above embodiments, an embodiment of the present disclosure further provides a computer-readable storage medium on which a control program for a motor drive circuit is stored. When the program is executed by a processor, the control method for a motor drive circuit of any of the above embodiments is implemented.

[0093] According to the computer-readable storage medium of the embodiment of the present disclosure, by executing a computer program of the control method of the motor drive circuit, the PFC unit and the inverter are synchronously controlled so that the operating state of the PFC unit matches the operating state of the inverter, thereby reducing energy loss on the bus capacitor, thereby reducing capacitor ripple, and further allowing the selection of capacitors with smaller capacitance.

[0094] Corresponding to the above embodiments, embodiments of the present disclosure further provide a motor controller. As shown in FIG17 , the motor controller 100 includes a memory 110 , a processor 120 , and a motor drive circuit control program stored in the memory 110 and executable on the processor 120 . When the processor 120 executes the program, the motor drive circuit control method of any of the above embodiments is implemented.

[0095] According to the motor controller of the embodiment of the present disclosure, a computer program of the control method of the motor drive circuit is executed by a processor, and the operating state of the PFC unit and the inverter are synchronously controlled to match the operating state of the PFC unit, thereby reducing the energy loss on the bus capacitor, thereby reducing the capacitor ripple, and further allowing the selection of capacitors with smaller capacity.

[0096] Corresponding to the above embodiment, the embodiment of the present disclosure further provides a motor drive circuit. As shown in FIG1 , the motor drive circuit includes: a PFC unit 10 , a bus capacitor C1 , an inverter 20 and a controller (not shown).

[0097] The bus capacitor C1 is provided at the output end of the PFC unit 10, and the inverter 20 is configured to drive the motor M to operate according to the bus voltage on the bus capacitor C1. The controller is configured to synchronously control the PFC unit 10 and the inverter 20 so that when the inverter 20 operates in the freewheeling state, the PFC unit 10 operates in the charging state; and when the inverter 20 operates in the driving state, the PFC unit 10 operates in the discharging state.

[0098] In some embodiments, the controller is further configured to: control the upper bridge switches (Q1, Q3, Q5) in the inverter 20 to be turned on at the same time and the lower bridge switches (Q2, Q4, Q6) to be turned off at the same time, and simultaneously control the switch Q7 in the PFC unit 10 to be turned on, so that the inverter 20 operates in the freewheeling state and the PFC unit 10 operates in the charging state.

[0099] In some embodiments, the controller is further configured to: control the upper bridge switches (Q1, Q3, Q5) in the inverter 20 to be turned off at the same time and the lower bridge switches (Q2, Q4, Q6) to be turned on at the same time, and simultaneously control the switch Q7 in the PFC unit 10 to be turned on, so that the inverter 20 operates in the freewheeling state and the PFC unit 10 operates in the charging state.

[0100] In some embodiments, the controller is further configured to: control one or two upper bridge switches in the inverter 20 to turn on and the remaining upper bridge switches to turn off, control the lower bridge switches corresponding to the turned-on upper bridge switches in the inverter 20 to turn off, and control the lower bridge switches corresponding to the turned-off upper bridge switches to turn on, and simultaneously control the switch Q7 in the PFC unit 10 to turn off, so that the inverter 20 operates in a driving state and the PFC unit 10 operates in a discharging state.

[0101] In some embodiments, the controller is further configured to: determine the ideal duty cycle and the required duty cycle of the switch tube Q7 when controlling the switch tube Q7 in the PFC unit 10; and determine the target duty cycle of the switch tube Q7 based on the relationship between the ideal duty cycle and the required duty cycle.

[0102] In some embodiments, the controller is further configured to: increase the required duty cycle when the required duty cycle is less than the ideal duty cycle, and use the current duty cycle as the target duty cycle when the switch current of the PFC unit 10 is greater than or equal to a preset current threshold.

[0103] In some embodiments, the controller is further configured to: when the required duty cycle is increased, if the switch current of the PFC unit 10 is less than a preset current threshold, then when the current duty cycle is greater than or equal to the ideal duty cycle, use the ideal duty cycle as the target duty cycle.

[0104] In some embodiments, the controller is further configured to: when the required duty cycle is greater than or equal to the ideal duty cycle, use the ideal duty cycle as the target duty cycle.

[0105] It should be noted that the specific implementation of the motor drive circuit of the embodiment of the present disclosure corresponds one-to-one to the specific implementation of the control method of the motor drive circuit of the aforementioned embodiment of the present disclosure, and will not be repeated here.

[0106] According to the motor drive circuit of the embodiment of the present disclosure, the controller synchronously controls the PFC unit and the inverter so that when the inverter operates in the freewheeling state, the PFC unit operates in the charging state; when the inverter operates in the driving state, the PFC unit operates in the discharging state. When the inverter is in the freewheeling state, it does not obtain energy from the capacitor, so the PFC unit is controlled to operate in the charging state; when the inverter is in the driving state, it obtains energy from the capacitor, so the PFC unit is controlled to directly discharge the inverter, so that the operating state of the PFC unit matches the operating state of the inverter, reducing the energy loss on the bus capacitor, thereby reducing the capacitor ripple, so that a capacitor with a smaller capacity can be selected, thereby reducing the cost of the motor drive circuit.

[0107] To achieve the above objectives, a home appliance is provided according to a fifth embodiment of the present disclosure. As shown in FIG18 , the home appliance 300 includes the aforementioned motor drive circuit 200 .

[0108] According to the household appliance of the embodiment of the present disclosure, by adopting the above-mentioned motor drive circuit, the PFC unit and the inverter are synchronously controlled so that the working state of the PFC unit matches the working state of the inverter, thereby reducing the energy loss on the bus capacitor, thereby reducing the capacitor ripple, and further allowing the selection of a capacitor with a smaller capacity.

[0109] It should be noted that the logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device), or in conjunction with such instruction execution system, apparatus, or device. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transmit a program for use by an instruction execution system, apparatus, or device, or in conjunction with such instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of computer-readable media include the following: an electrical connection portion having one or more wires (electronic device), a portable computer disk cartridge (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and portable compact disc read-only memory (CDROM). Furthermore, 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 it in another suitable manner if necessary, and then storing it in a computer memory.

[0110] It should be understood that various parts of the present disclosure can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used to implement: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0111] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0112] In addition, the terms "first" and "second" used in the embodiments of the present disclosure are only used for descriptive purposes and should not be understood as indicating or implying relative importance, or implicitly indicating the number of technical features indicated in the embodiments. Therefore, the features defined in the embodiments of the present disclosure with terms such as "first" and "second" can explicitly or implicitly indicate that the embodiment includes at least one such feature. In the description of the present disclosure, the word "plurality" means at least two or two or more, such as two, three, four, etc., unless otherwise clearly and specifically defined in the embodiments.

[0113] In this disclosure, unless otherwise clearly specified or limited in the embodiments, the terms "installed," "connected," "connect," and "fixed" appearing in the embodiments should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integral connection. It can also be a mechanical connection, an electrical connection, etc.; of course, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication between two elements, or the interaction between two elements. For those skilled in the art, the specific meanings of the above terms in this disclosure can be understood based on the specific implementation.

[0114] Although the embodiments of the present disclosure have been shown and described above, it is understood that the above embodiments are illustrative and are not to be construed as limitations on the present disclosure. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present disclosure.

Claims

1. A control method for a motor drive circuit, the motor drive circuit comprising a PFC unit, a bus capacitor and an inverter, the bus capacitor being arranged at an output end of the PFC unit, the inverter being configured to drive the motor to work according to a bus voltage on the bus capacitor, the method comprising: The PFC unit and the inverter are synchronously controlled so that When the inverter operates in the freewheeling state, the PFC unit operates in the charging state; When the inverter operates in a driving state, the PFC unit operates in a discharging state.

2. The control method of the motor drive circuit according to claim 1, wherein: The PFC unit and the inverter are synchronously controlled, comprising: The upper bridge switch tubes in the inverter are controlled to be turned on at the same time and the lower bridge switch tubes are controlled to be turned off at the same time, and the switch tubes in the PFC unit are controlled to be turned on at the same time, so that when the inverter operates in the freewheeling state, the PFC unit operates in the charging state.

3. The control method of the motor drive circuit according to claim 1, wherein: The PFC unit and the inverter are synchronously controlled, comprising: The upper bridge switch tubes in the inverter are controlled to be turned off and the lower bridge switch tubes are controlled to be turned on at the same time, and the switch tubes in the PFC unit are controlled to be turned on at the same time, so that when the inverter operates in the freewheeling state, the PFC unit operates in the charging state.

4. The control method of the motor drive circuit according to claim 1, wherein: The PFC unit and the inverter are synchronously controlled, comprising: Control one or two upper bridge switches in the inverter to turn on and the remaining upper bridge switches to turn off, control the lower bridge switches corresponding to the turned-on upper bridge switches in the inverter to turn off, control the lower bridge switches corresponding to the turned-off upper bridge switches to turn on, and simultaneously control the switches in the PFC unit to turn off, so that when the inverter works in a driving state, the PFC unit works in a discharging state.

5. The control method of the motor drive circuit according to any one of claims 1 to 4, wherein: When controlling the switch tube in the PFC unit, the method further includes: Determining an ideal duty cycle and a required duty cycle of the switch tube; According to the relationship between the ideal duty cycle and the required duty cycle, the target duty cycle of the switch tube is determined.

6. The control method of the motor drive circuit according to claim 5, wherein: Determining a target duty cycle of the switch tube according to a relationship between the ideal duty cycle and the required duty cycle includes: When the required duty cycle is less than the ideal duty cycle, the required duty cycle is increased, and when the switch tube current of the PFC unit is greater than or equal to a preset current threshold, the current duty cycle is used as the target duty cycle.

7. The control method of the motor drive circuit according to claim 6, wherein: Determining a target duty cycle of the switch tube according to a relationship between the ideal duty cycle and the required duty cycle also includes: In the case of increasing the required duty cycle, if the switch tube current of the PFC unit is less than a preset current threshold, then when the current duty cycle is greater than or equal to the ideal duty cycle, the ideal duty cycle is used as the target duty cycle.

8. The control method of the motor drive circuit according to claim 5, wherein: Determining a target duty cycle of the switch tube according to a relationship between the ideal duty cycle and the required duty cycle also includes: When the required duty cycle is greater than or equal to the ideal duty cycle, the ideal duty cycle is used as the target duty cycle.

9. A computer-readable storage medium storing a control program of a motor drive circuit, wherein the program, when executed by a processor, implements the control method of the motor drive circuit according to any one of claims 1 to 8.

10. A motor controller, comprising: A memory, a processor, and a control program for a motor drive circuit stored in the memory and executable on the processor, wherein when the processor executes the program, a control method for a motor drive circuit according to any one of claims 1 to 8 is implemented.

11. A motor drive circuit, comprising: A PFC unit, a bus capacitor and an inverter, wherein the bus capacitor is arranged at an output end of the PFC unit, and the inverter is configured to drive the motor to work according to the bus voltage on the bus capacitor; A controller is configured to synchronously control the PFC unit and the inverter so that When the inverter operates in the freewheeling state, the PFC unit operates in the charging state; When the inverter operates in a driving state, the PFC unit operates in a discharging state.

12. A household appliance comprising the motor driving circuit according to claim 11.

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