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

Abstract

The invention discloses a motor driving circuit and a control method thereof, 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 the output end of the PFC unit, and the inverter is configured to drive a motor to work according to the bus voltage on the bus capacitor. The method comprises the steps of performing synchronous control on a PFC unit and an inverter, so that the PFC unit works in a charging state under the condition that the inverter works in a follow current state; and when the inverter works in the driving state, the PFC unit works in the discharging state. According to the method, the PFC unit and the inverter are synchronously controlled, so that the working state of the PFC unit is matched with the working state of the inverter, the energy loss on the bus capacitor is reduced, the capacitor ripple is reduced, and the capacitor with smaller capacity can be selected.

Description

Technical Field

[0001] The present application 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

[0002] At present, the driving circuit of the air conditioner outdoor unit usually adopts a driving circuit composed of a rectifier bridge, a Boost (boost) rectifier and a compressor inverter circuit. The PFC (Power Factor Correction) drive and the compressor drive in the related technology are not related, so the energy provided by the PFC and the energy required by the compressor inverter are independent. The independent control of energy leads to the need to charge and discharge the bus capacitor, which increases the capacitor ripple. Therefore, a capacitor with a larger capacity is required. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, the first object of the present invention is to provide a control method for a motor drive circuit, by synchronously controlling a PFC unit and an inverter, so that the working state of the PFC unit matches the working state of the inverter, reducing the energy loss on the bus capacitor, thereby reducing the capacitor ripple, and further selecting a capacitor with a smaller capacity.

[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 motor controller.

[0006] A fourth objective of the present invention is to provide a motor driving circuit.

[0007] A fifth objective of the present invention is to provide a household appliance.

[0008] To achieve the above-mentioned purpose, a control method for a motor drive circuit is proposed according to an embodiment of a first aspect of the present invention. 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 work 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 works in a freewheeling state, the PFC unit works in a charging state; when the inverter works in a driving state, the PFC unit works in a discharging state.

[0009] According to the control method of the motor drive circuit of the embodiment of the present invention, the PFC unit and the inverter are synchronously controlled so that when the inverter works in the freewheeling state, the PFC unit works in the charging state; when the inverter works in the driving state, the PFC unit works 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 work 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 working state of the PFC unit matches the working 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.

[0010] According to one embodiment of the present invention, the PFC unit and the inverter are synchronously controlled, including: controlling the upper bridge switch tubes in the inverter to be turned on at the same time and the lower bridge switch tubes to be turned off at the same time, and simultaneously controlling the switch tubes in the PFC unit to be turned on, so that the PFC unit operates in a charging state when the inverter operates in a freewheeling state.

[0011] According to one embodiment of the present invention, the PFC unit and the inverter are synchronously controlled, including: controlling the upper bridge switch tubes in the inverter to be turned off at the same time and the lower bridge switch tubes to be turned on at the same time, and simultaneously controlling the switch tube in the PFC unit to be turned on, so that the PFC unit operates in a charging state when the inverter operates in a freewheeling state.

[0012] According to one embodiment of the present invention, the PFC unit and the inverter are synchronously controlled, including: controlling one or two upper bridge switches in the inverter 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 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 PFC unit works in a discharging state when the inverter works in a driving state.

[0013] According to one embodiment of the present invention, when controlling the switch tube in the PFC unit, the method also includes: determining the ideal duty cycle and the required duty cycle of the switch tube; and determining the target duty cycle of the switch tube according to the relationship between the ideal duty cycle and the required duty cycle.

[0014] According to one embodiment of the present invention, the target duty cycle of the switch 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, 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.

[0015] According to one embodiment of the present invention, the target duty cycle of the switch tube is determined based on the relationship between the ideal duty cycle and the required duty cycle, and also includes: when the required duty cycle is increased, 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.

[0016] According to an embodiment of the present invention, determining the target duty cycle of the switch tube according to 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.

[0017] To achieve the above-mentioned purpose, according to a second aspect of the present invention, a computer-readable storage medium is provided, on which a control program for a motor drive circuit is stored. When the program is executed by a processor, a control method for a motor drive circuit according to any of the above-mentioned embodiments is implemented.

[0018] According to the computer-readable storage medium of the embodiment of the present invention, by executing the computer program of the control method of the 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 selecting a capacitor with a smaller capacity.

[0019] To achieve the above-mentioned purpose, according to an embodiment of the third aspect of the present invention, a motor controller is proposed, comprising: a memory, a processor, and a control program for a motor drive circuit stored in the memory and executable 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.

[0020] According to the motor controller of the embodiment of the present invention, a computer program of the control method of the motor drive circuit is executed by a processor, and the working state of 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 furthermore, a capacitor with a smaller capacity can be selected.

[0021] To achieve the above-mentioned purpose, according to a fourth aspect of the present invention, an embodiment is provided, 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 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 works in a freewheeling state, the PFC unit works in a charging state; when the inverter works in a driving state, the PFC unit works in a discharging state.

[0022] According to the motor drive circuit of the embodiment of the present invention, the controller synchronously controls the PFC unit and the inverter, so that when the inverter works in the freewheeling state, the PFC unit works in the charging state; when the inverter works in the driving state, the PFC unit works 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 work 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 discharge directly to the inverter, so that the working state of the PFC unit matches the working 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.

[0023] To achieve the above objective, a household appliance is proposed according to a fifth aspect of the present invention, comprising the aforementioned motor drive circuit.

[0024] According to the household appliance of the embodiment of the present invention, 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.

[0025] 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

[0026] Figure 1 is a circuit diagram of a motor drive according to an embodiment of the present invention;

[0027] Figure 2 is a waveform diagram of a driving signal of an inverter according to an embodiment of the present invention;

[0028] Figures 3 to 6 is a schematic diagram of current flow of an inverter in different working states according to an embodiment of the present invention;

[0029] Figure 7 is a flow chart of a control method of a motor drive circuit according to an embodiment of the present invention;

[0030] Figure 8 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 an embodiment of the present invention;

[0031] Fig. 9 is a schematic diagram of current flow when the inverter is in a (1.0.0) working state and the PFC unit is in a discharging state according to an embodiment of the present invention;

[0032] Fig.10 is a schematic diagram of current flow when the inverter is in a (1.1.0) working state and the PFC unit is in a discharging state according to an embodiment of the present invention;

[0033] Fig.11 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 an embodiment of the present invention;

[0034] Fig.12 is a waveform diagram of a driving signal of an inverter according to another embodiment of the present invention;

[0035] Fig.13 is a waveform diagram of an ideal duty cycle and a driving signal of an inverter according to an embodiment of the present invention;

[0036] Fig.14 is a waveform diagram of an ideal duty cycle and a required duty cycle according to an embodiment of the present invention;

[0037] Fig.15 is a waveform diagram of an ideal duty cycle and a required duty cycle according to another embodiment of the present invention;

[0038] Fig.16 is a flow chart of a method for determining a target duty cycle according to an embodiment of the present invention;

[0039] Fig.17 is a system schematic diagram of a motor controller according to an embodiment of the present invention;

[0040] Fig.18 is a system schematic diagram of a household appliance according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] 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.

[0042] It should be noted that this application is made based on the inventor's understanding and research of the following issues:

[0043] like Figure 1 As shown, the motor driving circuit includes a PFC unit 10, a bus capacitor C1 and an inverter 20. The bus capacitor C1 is arranged at the output end of the PFC unit 10. The inverter 20 is configured to drive the motor M to work according to the bus voltage on the bus capacitor C1.

[0044] The PFC unit 10 includes a first inductor L1, a seventh diode D7 and a seventh switch tube Q7, wherein one end of the first inductor L1 is suitable for connecting to the positive electrode of the DC power supply, the other end of the first inductor L1 is connected to the anode of the seventh diode D7, the cathode of the seventh diode D7 is connected to one end of the bus capacitor C1, the first end of the seventh switch tube Q7 is respectively connected to the other end of the first inductor L1 and the anode of the seventh diode D7, the second end of the seventh switch tube Q7 is connected to the other end of the bus capacitor C1, and is suitable for connecting to the negative electrode of the DC power supply. When the seventh switch tube Q7 is turned on, the PFC unit 10 works in a charging state, and when the seventh switch tube Q7 is turned off, the PFC unit 10 works in a discharging state.

[0045] Further, 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 a first diode D1 to a fourth diode D4, the anode of the first diode D1 is suitable for connecting 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 suitable for connecting 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, and the cathode of the fourth diode D4 is connected to the anode of the second diode D2.

[0046] The inverter 20 includes 6 switch tubes, namely the first switch tube Q1 to the sixth switch tube Q6. The first switch tube Q1 and the second switch tube Q2 are the first bridge arm of the inverter 20, the third switch tube Q3 and the fourth switch tube Q4 are the second bridge arm of the inverter 20, and the fifth switch tube Q5 and the sixth switch tube Q6 are the third bridge arm of the inverter 20. The upper bridge switch tube (Q1, Q3, Q5) and the lower bridge switch tube (Q2, Q4, Q6) of each bridge arm are complementary, that is, when the upper bridge switch tube (Q1, Q3, Q5) is turned on, the lower bridge switch tube (Q2, Q4, Q6) is turned off, and when the upper bridge switch tube (Q1, Q3, Q5) is turned off, the lower bridge switch tube (Q2, Q4, Q6) is turned on. Therefore, as long as the driving waveform of the upper bridge switch tube (Q1, Q3, Q5) is known, the driving waveform of the lower bridge switch tube (Q2, Q4, Q6) can be obtained. 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". Figure 2 As shown, 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 works in the (0.0.0) state, the current flow in the inverter 20 is as follows Figure 3 When the inverter 20 is operating in the (1.0.0) state, the current in the inverter 20 is as follows: Figure 4 When the inverter 20 is operating in the (1.1.0) state, the current in the inverter 20 is as follows: Figure 5 When the inverter 20 is operating in the (1.1.1) state, the current flow in the inverter 20 is as follows: Figure 6 When the inverter 20 works 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 works 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.

[0047] In the related art, the PFC unit 10 and the inverter 20 are controlled separately. When the PFC unit 10 is charged, if the inverter 20 is in the driving state, the bus capacitor C1 needs to be discharged; when the PFC unit 10 is discharged, if the inverter 20 is in the freewheeling state, the bus capacitor C1 needs to be charged, which increases the capacitor ripple. Therefore, when designing the circuit, a capacitor with a larger capacity needs to be selected.

[0048] Based on this, an embodiment of the present invention provides a motor drive circuit and a control method thereof, a motor controller, a household appliance, and a storage medium. 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 then a capacitor with a smaller capacity can be selected.

[0049] The motor driving circuit and control method thereof, the motor controller, the household appliance, and the storage medium according to the embodiments of the present invention are described below with reference to the accompanying drawings.

[0050] like Figure 1 As shown, the motor driving circuit includes a PFC unit 10, a bus capacitor C1 and an inverter 20. The bus capacitor C1 is arranged at the output end of the PFC unit 10. The inverter 20 is configured to drive the motor M to work according to the bus voltage on the bus capacitor C1.

[0051] Figure 7 FIG. 1 is a flow chart of a control method of a motor drive circuit according to an embodiment of the present invention. Figure 7 As shown, the control method of the motor drive circuit includes the following steps:

[0052] S101, synchronously control the PFC unit and the inverter so that

[0053] When the inverter works in the freewheeling state, the PFC unit works in the charging state;

[0054] When the inverter operates in a driving state, the PFC unit operates in a discharging state.

[0055] Specifically, Figure 8-Figure 11 As shown, Figure 8 and Fig.11 The current flow direction when the inverter 20 works in the freewheeling state and the PFC works in the charging state is shown. When the inverter 20 works in the freewheeling state, the bus capacitor C1 is not required to supply power. Therefore, the PFC unit 10 is controlled to work in the charging state, so that the energy on the bus capacitor C1 will not be lost. Fig. 9 and Fig.10 The figure shows the current flow when the inverter 20 works in the driving state and the PFC unit 10 works in the discharging state. When the inverter 20 works in the driving state, the bus capacitor C1 is required to supply power. Therefore, the PFC unit 10 is controlled to work in the discharging state so that the DC power supply and the PFC unit 10 can directly supply power to the motor M. In this way, the electric energy of the motor M can be obtained from the DC power supply, the PFC unit 10 and the bus capacitor C1, thereby reducing the energy loss on the bus capacitor C1.

[0056] In the above embodiment, the working state of the PFC unit is matched with the working state of the inverter, so that when the inverter is in the freewheeling state, the PFC unit works in the charging state, and when the inverter is in the driving state, the PFC unit works in the discharging state, thereby reducing the energy loss of the bus capacitor and thus reducing the ripple of the capacitor. In this way, when designing the circuit, a capacitor with a smaller capacity can be selected, thereby reducing the circuit cost.

[0057] In some embodiments, Figure 8 As shown, 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 at the same time and the lower bridge switches (Q2, Q4, Q6) to be turned off at the same time, and simultaneously controlling the switch Q7 in the PFC unit 10 to be turned on, so that the inverter 20 works in the freewheeling state and the PFC unit 10 works in the charging state.

[0058] Specifically, when the upper bridge switches (Q1, Q3, Q5) in the inverter 20 are turned on at the same time and the lower bridge switches (Q2, Q4, Q6) are turned off at the same time, the inverter 20 operates in the (0.0.0) state, and the inverter 20 operates in the freewheeling state. When the switch Q7 in the PFC unit 10 is turned on, the DC power supply charges the first inductor L1 in the PFC unit 10, and the PFC unit 10 operates in the charging state.

[0059] In some embodiments, Fig.11As shown, the PFC unit 10 and the inverter 20 are synchronously controlled, including: controlling the upper bridge switch tubes (Q1, Q3, Q5) in the inverter 20 to be turned off at the same time and the lower bridge switch tubes (Q2, Q4, Q6) to be turned on at the same time, and simultaneously controlling the switch tube Q7 in the PFC unit 10 to be turned on, so that the inverter 20 works in the freewheeling state and the PFC unit 10 works in the charging state.

[0060] That is, when the upper bridge switches (Q1, Q3, Q5) in the inverter 20 are turned off at the same time and the lower bridge switches (Q2, Q4, Q6) are turned on at the same time, the inverter 20 operates in the (1.1.1) state, and the inverter 20 operates in the freewheeling state. When the switch Q7 in the PFC unit 10 is turned on, the DC power supply charges the first inductor L1 in the PFC unit 10, and the PFC unit 10 operates in the charging state.

[0061] In some embodiments, Fig. 9 and Fig.10 As shown, 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, 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, and simultaneously controlling the switch Q7 in the PFC unit 10 to turn off, so that the PFC unit 10 works in a discharging state when the inverter 20 works in a driving state.

[0062] 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 be turned on and the remaining upper bridge switches to be turned off, and controlling the lower bridge switches corresponding to the turned-on upper bridge switches in the inverter 20 to be turned off and the lower bridge switches corresponding to the turned-off upper bridge switches to be turned on, the inverter 20 works in the remaining working states, and at the same time controls the switch Q7 in the PFC unit 10 to be turned 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.

[0063] For example, Fig. 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, Fig.10The current flow direction is shown 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.

[0064] It should be noted that, in actual applications, the waveform of the drive signal of the inverter 20 is not limited to Figure 2 The waveform shown may also be other waveforms.

[0065] To adopt when adopting Fig.12 Taking the waveform shown as an example, when the inverter 20 is controlled to work 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 work in the (1.0.0) and (1.0.1) states, the switch tube of the PFC unit 10 is controlled to be turned off.

[0066] 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 according to a relationship between the ideal duty cycle and the required duty cycle.

[0067] Specifically, the ideal duty cycle of the switch tube of the PFC unit is determined according to the drive signal of the inverter, such as Fig.13 As shown, 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 an ideal situation, the control period of the PFC unit is T pfc is the inverter control period T m The carrier frequency of the PFC unit is half of that of the inverter, that is, the carrier frequency of the PFC unit is twice that of the inverter. The required duty cycle is determined based on the bus voltage, bus voltage reference value, and switch tube current, and may differ from the waveform of the ideal duty cycle. Therefore, it is necessary to determine the target duty cycle of the switch tube based on the relationship between the ideal duty cycle and the required duty cycle.

[0068] In some embodiments, Fig.14 As shown, according to the relationship between the ideal duty cycle and the required duty cycle, the target duty cycle of the switch tube is determined, including: 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.

[0069] 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, the demand duty cycle needs to be gradually increased 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.

[0070] Furthermore, in some embodiments, the target duty cycle of the switch tube is determined based on the relationship between the ideal duty cycle and the required duty cycle, and it also includes: when the required duty cycle is increased, 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.

[0071] 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.

[0072] In some embodiments, Fig.14 As shown, according to the relationship between the ideal duty cycle and the required duty cycle, the target duty cycle of the switch tube is determined, and 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.

[0073] 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 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.

[0074] In an optional embodiment, if Fig.15As shown in FIG. 1 , 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, and 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 uses the high level stage of the ideal duty cycle as the boundary, 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, and 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 at a low level, the target duty cycle is also at a low level; and 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, and when the demand duty cycle is at a low level, the target duty cycle is also at a low level; and the duty cycle area of ​​the target duty cycle is the same as the duty cycle area of ​​the ideal duty cycle.

[0075] The technical solution of the present application is further described in detail below in conjunction with specific implementation methods:

[0076] like Fig.16 As shown, the method for determining the target duty cycle of the switch tube includes the following steps:

[0077] S201, determining an ideal duty cycle according to a driving signal of the inverter, and determining a required duty cycle according to a bus voltage, a bus voltage reference value, and a switch tube current.

[0078] S202, comparing the ideal duty cycle with the required duty cycle.

[0079] S203: If the required duty cycle is greater than or equal to the ideal duty cycle, execute step S204.

[0080] S204: Taking the ideal duty cycle as the target duty cycle.

[0081] S205: If the required duty cycle is less than the ideal duty cycle, execute step S206.

[0082] S206, increasing the required duty cycle and detecting the switch tube current of the PFC unit.

[0083] 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.

[0084] S208: Taking the current duty cycle as the target duty cycle.

[0085] S209, determine whether the current duty cycle reaches the ideal duty cycle. If the current duty cycle reaches the ideal duty cycle, execute step S210. If the current duty cycle does not reach the ideal duty cycle, return to step S206.

[0086] S210, taking the ideal duty cycle as the target duty cycle.

[0087] 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.

[0088] In summary, according to the control method of the motor drive circuit of the embodiment of the present invention, the PFC unit and the inverter are synchronously controlled so that when the inverter works in the freewheeling state, the PFC unit works in the charging state; when the inverter works in the driving state, the PFC unit works in the discharging state. When the inverter is in the freewheeling state, it will not obtain energy from the capacitor, therefore, the PFC unit is controlled to work 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 working state of the PFC unit matches the working 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.

[0089] Corresponding to the above embodiments, an embodiment of the present invention 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.

[0090] According to the computer-readable storage medium of the embodiment of the present invention, by executing the computer program of the control method of the 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 selecting a capacitor with a smaller capacity.

[0091] Corresponding to the above embodiment, the embodiment of the present invention further provides a motor controller. Fig.17As shown, the motor controller 100 includes: a memory 110, a processor 120, and a control program for the motor drive circuit stored in the memory 110 and executable on the processor 120. When the processor 120 executes the program, the control method for the motor drive circuit of any of the aforementioned embodiments is implemented.

[0092] According to the motor controller of the embodiment of the present invention, a computer program of the control method of the motor drive circuit is executed by a processor, and the working state of 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 furthermore, a capacitor with a smaller capacity can be selected.

[0093] Corresponding to the above embodiment, an embodiment of the present invention further provides a motor drive circuit. Figure 1 As shown, the motor driving circuit includes: a PFC unit 10, a bus capacitor C1, an inverter 20 and a controller (not shown).

[0094] The bus capacitor C1 is arranged at the output end of the PFC unit 10, and the inverter 20 is configured to drive the motor M to work 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 works in the freewheeling state, the PFC unit 10 works in the charging state; when the inverter 20 works in the driving state, the PFC unit 10 works in the discharging state.

[0095] In some embodiments, the controller is also 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.

[0096] In some embodiments, the controller is also 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.

[0097] 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, and control 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 control the switch Q7 in the PFC unit 10 to turn off, so that when the inverter 20 works in the driving state, the PFC unit 10 works in the discharging state.

[0098] In some embodiments, the controller is further configured to: determine the ideal duty cycle and 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.

[0099] In some embodiments, the controller is further configured to increase the demanded duty cycle when the demanded 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.

[0100] 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.

[0101] 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.

[0102] It should be noted that the specific implementation of the motor drive circuit in the embodiment of the present invention corresponds one to one with the specific implementation of the control method of the motor drive circuit in the aforementioned embodiment of the present invention, and will not be described in detail herein.

[0103] According to the motor drive circuit of the embodiment of the present invention, the controller synchronously controls the PFC unit and the inverter, so that when the inverter works in the freewheeling state, the PFC unit works in the charging state; when the inverter works in the driving state, the PFC unit works 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 work 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 discharge directly to the inverter, so that the working state of the PFC unit matches the working 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.

[0104] To achieve the above-mentioned purpose, a household appliance is provided according to a fifth embodiment of the present invention. Fig.18 As shown, the household appliance 300 includes the aforementioned motor driving circuit 200 .

[0105] According to the household appliance of the embodiment of the present invention, 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] In addition, the terms "first", "second", etc. used in the embodiments of the present invention 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 present embodiment. Therefore, the features defined by the terms "first", "second", etc. in the embodiments of the present invention can explicitly or implicitly indicate that the embodiment includes at least one of the features. In the description of the present invention, the word "multiple" means at least two or two or more, such as two, three, four, etc., unless otherwise clearly and specifically defined in the embodiments.

[0110] In the present invention, unless otherwise clearly specified or limited in the embodiments, the terms "installed", "connected", "connected" and "fixed" etc. in the embodiments should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integrated connection. It can be understood that 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 connection of two elements, or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific implementation situation.

[0111] 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 motor drive circuit, characterized in that: The motor drive circuit comprises 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 a bus voltage on the bus capacitor. The method comprises: 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 method according to claim 1, characterized in that 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 method according to claim 1, characterized in that: 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 method according to claim 1, characterized in that: 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 method according to any one of claims 1 to 4, characterized in that 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 method according to claim 5, characterized in that 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 method according to claim 6, characterized in that 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 method according to claim 5, characterized in that 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, characterized in that: A control program of the motor drive circuit is stored thereon, and when the program is executed by the processor, the control method of the motor drive circuit according to any one of claims 1-8 is implemented.

10. A motor controller, characterized in that: include: 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, characterized in that: include: 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, characterized in that: Comprising the motor driving circuit according to claim 11.

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