A three-phase power conversion circuit, a household electrical appliance, a control method and a device

Abstract

Embodiments of the present application disclose a three-phase power conversion circuit, a household electrical appliance, a control method and a device, including: the three-phase AC input end of a power rectification module is connected to a three-phase power supply, and the positive and negative DC output ends are connected in parallel with a first capacitor and a second capacitor connected in series with each other; both ends of the first capacitor are connected in parallel with a first half-bus load, and the discharge module includes at least one of the following: a second discharge module connected in parallel at both ends of the second capacitor, a third discharge module connected in parallel at the positive and negative DC output ends; the discharge module is used to operate in a discharge state to control the voltage of the first capacitor and / or the second capacitor to be reduced to less than a second voltage threshold. In this way, by configuring a discharge module for the second capacitor without a connected load, it is possible to perform a discharge operation when the voltage of the second capacitor rises, reduce the voltage of the second capacitor, avoid overvoltage problems when the half-bus load operates alone, and ensure the safe operation of the half-bus load.

Description

Technical Field

[0001] The present application relates to air conditioning control technology, and in particular to a three-phase power conversion circuit, household appliance, control method and device. Background Art

[0002] In a high-efficiency variable frequency air-conditioning system powered by a three-phase power supply, in addition to the variable frequency compressor load, there is also a DC fan load. Some air-conditioning systems have one DC fan, and some systems have two DC fans or even more.

[0003] The three-phase power supply outputs a high-voltage DC bus voltage after passing through the rectifier circuit. The compressor load is connected to the high-voltage DC bus voltage. The fan load is not powered by the high-voltage DC bus voltage, but is powered by another independent phase voltage after rectification. The use of an independent phase voltage rectifier to supply power to the fan load causes the load of this phase to be higher than the other two phases, and the current harmonics of this phase are significantly larger, resulting in an unbalanced three-phase current and difficulty in meeting the harmonic requirements of the International Electrotechnical Commission (IEC). Summary of the invention

[0004] In order to solve the above technical problems, the embodiments of the present application hope to provide a three-phase power conversion circuit, household appliance, control method and device.

[0005] The technical solution of this application is implemented as follows:

[0006] In a first aspect, a three-phase power conversion circuit is provided, comprising: a three-phase power supply, a power rectifier module, a first capacitor, a second capacitor, a first half bus load and a discharge module; wherein,

[0007] The three-phase AC input end of the power rectifier module is connected to the three-phase power supply, and the positive and negative DC output ends are connected in parallel to the first capacitor and the second capacitor which are connected in series with each other;

[0008] The first half bus load is connected in parallel to both ends of the first capacitor.

[0009] The discharge module includes at least one of the following: a second discharge module connected in parallel at both ends of the second capacitor, and a third discharge module connected in parallel at the positive and negative DC output ends;

[0010] The discharge module is used to control the discharge module to operate in a discharge state when the voltage of the first capacitor and / or the second capacitor is greater than or equal to a first voltage threshold, so as to control the voltage of the first capacitor and / or the second capacitor to decrease to less than a second voltage threshold;

[0011] Wherein, the first voltage threshold is greater than or equal to the second voltage threshold.

[0012] In the above solution, the discharge module also includes a first discharge module connected in parallel at both ends of the first capacitor.

[0013] In the above solution, the three-phase power conversion circuit further includes a second half-bus load, and the second half-bus load is connected in parallel to both ends of the second capacitor;

[0014] The discharge module comprises any two of: a first discharge module connected in parallel at both ends of the first capacitor, a second discharge module connected in parallel at both ends of the second capacitor, and a third discharge module connected in parallel at the positive and negative DC output ends;

[0015] Alternatively, the discharge module includes: a third discharge module connected in parallel with the positive and negative DC output terminals.

[0016] In the above solution, the three-phase power conversion circuit also includes a full bus load, and the positive and negative DC output terminals are connected in parallel with the full bus load.

[0017] In the above solution, the power rectifier module includes: a three-phase rectifier bridge and a bidirectional switch component,

[0018] The three-phase rectifier bridge includes a first bridge arm, a second bridge arm and a third bridge arm connected in parallel; the bidirectional switch assembly includes a first bidirectional switch, a second bidirectional switch and a third bidirectional switch, one end of the first bidirectional switch is connected to the midpoint of the first bridge arm, one end of the second bidirectional switch is connected to the midpoint of the second bridge arm, and one end of the third bidirectional switch is connected to the midpoint of the third bridge arm;

[0019] The other end of the first bidirectional switch, the other end of the second bidirectional switch, and the other end of the third bidirectional switch are all connected to a common end between the first capacitor and the second capacitor.

[0020] In the above solution, the three-phase power conversion circuit further includes: a controller, the discharge module includes a power switch tube and a power consumption device connected in series;

[0021] The controller is connected to the control end of the power switch tube, and is used to adjust the duty cycle of the power switch tube when the voltage of the first capacitor and / or the voltage of the second capacitor is greater than a voltage threshold, and control the power switch tube to be in a closed state, so that the power-consuming device works.

[0022] In the above solution, the power switch tube includes one of a metal-oxide semiconductor field effect transistor, an insulated gate bipolar transistor, a triode, and a thyristor;

[0023] The power-consuming device includes at least one of a resistor, a motor, and a compressor.

[0024] In a second aspect, a household appliance is provided, wherein the household appliance comprises the three-phase power conversion circuit as described in any one of the first aspects.

[0025] In a third aspect, a control method for a three-phase power conversion circuit is provided, wherein the three-phase power conversion circuit includes the three-phase power conversion circuit as described in any one of the first aspects above; the method includes:

[0026] Obtaining a target capacitor voltage; wherein the target capacitor is the first capacitor and / or the second capacitor in the three-phase power conversion circuit,

[0027] The target capacitor voltage is greater than or equal to a first voltage threshold, generating a start control signal;

[0028] According to the start control signal, the discharge module is controlled to operate in a discharge state to control the target capacitor voltage to decrease to less than a second voltage threshold; wherein the first voltage threshold is greater than or equal to the second voltage threshold.

[0029] In the above solution, the discharge module includes a power switch tube and a power consumption device connected in series;

[0030] The target capacitor voltage is greater than or equal to a first voltage threshold, and a start control signal is generated, comprising:

[0031] The target capacitor voltage is greater than or equal to the first voltage threshold, and the duty cycle of the switch module of the discharge module is set according to the voltage range of the target capacitor voltage to generate the start control signal;

[0032] The step of controlling the discharge module to operate in a discharge state according to the start control signal includes:

[0033] According to the start control signal, the power switch tube is controlled to be in a closed state.

[0034] In the above solution, the target capacitor is the first capacitor or the second capacitor in the three-phase power conversion circuit that is not connected to the half-bus load;

[0035] When the target capacitance is the first capacitance, the first capacitance threshold is set according to the withstand voltage value of the first capacitance or the upper limit value of the full bus voltage;

[0036] When the target capacitance is the second capacitance, the first capacitance threshold is set according to the withstand voltage of the second capacitance or the upper limit value of the full bus voltage.

[0037] In the above scheme, the three-phase power conversion circuit also includes a full bus load, and the positive and negative DC output terminals are connected in parallel with the full bus load;

[0038] The method further comprises:

[0039] When the full bus load is turned on and the first half bus load is turned off, the discharge circuit is controlled to be in a closed state, or the discharge circuit is controlled to be in a low-power working state.

[0040] In a fourth aspect, a control device for a three-phase power conversion circuit is provided, comprising: a processor and a memory configured to store a computer program that can be run on the processor,

[0041] Wherein, the processor is configured to execute the steps of the aforementioned method when running the computer program.

[0042] In a fifth aspect, a computer storage medium is provided, on which a computer program is stored, wherein the computer program implements the steps of the aforementioned method when executed by a processor.

[0043] In the embodiment of the present application, a three-phase power conversion circuit, household appliance, control method and device are provided, including: a three-phase power supply, a power rectifier module, a first capacitor, a second capacitor, a first half-bus load, a discharge module and a controller; wherein the three-phase AC input end of the power rectifier module is connected to the three-phase power supply, the positive and negative DC output ends are connected in parallel to the first capacitor and the second capacitor connected in series with each other; the two ends of the first capacitor are connected in parallel to the first half-bus load, and the discharge module includes at least one of the following: a second discharge module connected in parallel to the two ends of the second capacitor, and a third discharge module connected in parallel to the positive and negative DC output ends; the discharge module is used to control the discharge module to work in a discharge state when the voltage of the first capacitor and / or the second capacitor is greater than or equal to the first voltage threshold, so as to control the voltage of the first capacitor and / or the second capacitor to be reduced to less than the second voltage threshold. In this way, by configuring a discharge module for the second capacitor that is not connected to the load, a discharge operation can be performed when the voltage of the second capacitor rises, the voltage of the second capacitor can be reduced, and the overvoltage problem when the half-bus load is running alone can be avoided, thereby ensuring the safe operation of the half-bus load. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A first topology diagram of a three-phase power conversion circuit in an embodiment of the present application;

[0045] Figure 2 A second topology diagram of the three-phase power conversion circuit in an embodiment of the present application;

[0046] Figure 3 A third topology diagram of the three-phase power conversion circuit in the embodiment of the present application;

[0047] Figure 4 A fourth topology diagram of the three-phase power conversion circuit in the embodiment of the present application;

[0048] Figure 5A fifth topology diagram of the three-phase power conversion circuit in the embodiment of the present application;

[0049] Figure 6 A sixth topology diagram of the three-phase power conversion circuit in the embodiment of the present application;

[0050] Figure 7 A first topological diagram of the discharge module in an embodiment of the present application;

[0051] Figure 8 A second topological diagram of the discharge module in the embodiment of the present application;

[0052] Fig. 9 The third topological diagram of the discharge module in the embodiment of the present application;

[0053] Fig.10 The seventh topology diagram of the three-phase power conversion circuit in the embodiment of the present application;

[0054] Fig.11 The eighth topological diagram of the three-phase power conversion circuit in the embodiment of the present application;

[0055] Fig.12 This is a first flow chart of a control method for a three-phase power conversion circuit in an embodiment of the present application;

[0056] Fig.13 A second flow chart of the control method of the three-phase power conversion circuit in the embodiment of the present application;

[0057] Fig.14 Schematic diagram of the composition structure of the control device of the three-phase power conversion circuit in the embodiment of the present application. DETAILED DESCRIPTION

[0058] In order to enable a more detailed understanding of the features and technical contents of the embodiments of the present application, the implementation of the embodiments of the present application is described in detail below in conjunction with the accompanying drawings. The attached drawings are for reference only and are not used to limit the embodiments of the present application.

[0059] Figure 1 is a first topology diagram of the three-phase power conversion circuit in the embodiment of the present application, such as Figure 1 As shown, the three-phase power conversion circuit includes: a three-phase power supply 10, a power rectifier module 11, a first capacitor 12, a second capacitor 13, a first half bus load 14 and a discharge module; wherein,

[0060] The three-phase AC input end of the power rectifier module 11 is connected to the three-phase power supply 10, and the positive and negative DC output ends are connected in parallel to the first capacitor 12 and the second capacitor 13 which are connected in series with each other;

[0061] The first half bus load 14 is connected in parallel to both ends of the first capacitor 12;

[0062] The discharge module includes at least one of the following: a second discharge module 151 connected in parallel to both ends of the second capacitor, and a third discharge module 152 connected in parallel to the positive and negative DC output ends;

[0063] The discharge module is used to control the discharge module to operate in a discharge state when the voltage of the first capacitor 12 and / or the second capacitor 13 is greater than a voltage threshold, so as to control the voltage of the first capacitor 12 and / or the second capacitor 13 to decrease to less than the voltage threshold;

[0064] Wherein, the first voltage threshold is greater than or equal to the second voltage threshold.

[0065] exist Figure 1 In this embodiment, the three-phase AC source of the three-phase power supply 10 is connected to the three-phase AC input terminal of the rectifier module 11 through the inductors L1 , L2 and L3 respectively.

[0066] exist Figure 1 In this embodiment, the power rectifier module 11 includes: a three-phase rectifier bridge and a bidirectional switch component,

[0067] The three-phase rectifier bridge includes a first bridge arm, a second bridge arm and a third bridge arm connected in parallel; the bidirectional switch assembly includes a first bidirectional switch, a second bidirectional switch and a third bidirectional switch, one end of the first bidirectional switch is connected to the midpoint of the first bridge arm, one end of the second bidirectional switch is connected to the midpoint of the second bridge arm, and one end of the third bidirectional switch is connected to the midpoint of the third bridge arm;

[0068] The other end of the first bidirectional switch, the other end of the second bidirectional switch, and the other end of the third bidirectional switch are all connected to the common end between the first capacitor and the second capacitor. By controlling the on and off of each bidirectional switch in the bidirectional switch assembly, the charging and discharging operations of the inductor are realized.

[0069] The first bridge arm includes a first diode D1 and a second diode D2, the second bridge arm includes a third diode D3 and a fourth diode D4, and the third bridge arm includes a fifth diode D5 and a sixth diode D6.

[0070] The first bidirectional switch, the second bidirectional switch and the third bidirectional switch in the bidirectional switch assembly may each include two power switch tubes connected in reverse series, and both power switch tubes are connected in reverse parallel with a diode. Exemplarily, the first bidirectional switch includes a first IGBT module T1 and a second IGBT module T2, the second bidirectional switch includes a third IGBT module T3 and a fourth IGBT module T4, and the third bidirectional switch includes a fifth IGBT module T5 and a sixth IGBT module T6.

[0071] The positive and negative DC output terminals specifically include a positive bus terminal and a negative bus terminal, and the positive bus terminal is connected to the negative bus terminal through a first capacitor C1 and a second capacitor C2 in sequence.

[0072] It should be noted that the full bus in the embodiment of the present application refers to the positive and negative busbars ( Figure 1 Between point P and point N), half bus refers to the midpoint of the two-stage capacitor series connection in the high-voltage DC bus filter circuit ( Figure 1 Point O) and positive busbar ( Figure 1 The upper busbar is between the middle point of the two-stage capacitor and the negative busbar ( Figure 1 The middle point of the first capacitor C1 and the second capacitor C2 is the lower half bus, and the upper half bus and the lower half bus are both half bus. Exemplarily, the middle point of the first capacitor C1 and the second capacitor C2 connected in series and the positive bus terminal is the upper half bus, and the middle point of the first capacitor C1 and the second capacitor C2 connected in series and the negative bus terminal is the lower half bus.

[0073] It should be noted that Figure 1 The first capacitor C1 is the upper bus capacitor, the first half bus load is the upper bus load, and the second capacitor C2 is the lower bus capacitor. Figure 1 It is not used to limit the connection position of the capacitors in the present application. In the embodiment of the present application, the first capacitor C1 can also be connected to the lower bus as a lower bus capacitor, and the second capacitor C2 can also be connected to the upper bus as an upper bus capacitor, that is, the bus end is connected to the negative bus end through the second capacitor C2 and the first capacitor C1 in sequence.

[0074] In some embodiments, when a first half-bus load is connected in parallel at both ends of the first capacitor, the discharge modules can be selected and set in the following order: (1) a second discharge module 151 is connected in parallel at both ends of the second capacitor 13 not connected to the half-bus load; (2) a third discharge module 152 (such as Figure 2 (3) connecting a second discharge module 151 in parallel at both ends of the second capacitor 13 not connected to the half-bus load, and connecting a third discharge module 152 (as shown) in parallel at the positive and negative DC output ends. Figure 2 shown).

[0075] When the first half bus load 14 is running alone, the second capacitor inevitably has a slow voltage rise, and the limit of its voltage rise is the full bus voltage value when the rectification is not controlled (in the case of 380V effective value input, the value is 537V, which is greater than the maximum allowable voltage of the existing commonly used electrolytic capacitor 450V). Therefore, 1) when the full bus load is not working or fails to work, the first half bus load cannot operate for a long time; 2) when the full bus load is suddenly closed or changes rapidly, the voltage of the first capacitor is difficult to control in time, which may cause the second capacitor to overvoltage or even fail. Therefore, by adding a discharge module, it is possible to perform a discharge operation when the second capacitor voltage rises, thereby reducing the second capacitor voltage to a safe voltage range, avoiding overvoltage, and not being affected by the full bus load.

[0076] In some embodiments, the discharge module further includes a first discharge module 153 connected in parallel across the first capacitor. That is, the discharge module may include at least two of the first discharge module 153 , the second discharge module 151 and the third discharge module 152 .

[0077] like Figure 4 As shown, in some embodiments, the three-phase power conversion circuit further includes a second half-bus load 16 , and the second half-bus load 16 is connected in parallel to both ends of the second capacitor 13 .

[0078] When the three-phase power conversion circuit includes the first half bus load 14 and the second half bus load 16, the discharge module can be selected and set in the following order: (1) the discharge module includes a first discharge module 153 connected in parallel at both ends of the first capacitor 12 and a second discharge module 151 connected in parallel at both ends of the second capacitor 13, such as Figure 4 As shown. (2) The discharge module includes a second discharge module 151, which is used to simultaneously control the first capacitor voltage and the second capacitor voltage to be within a safe voltage range. (3) The discharge module includes: a first discharge module 153 and a third discharge module 152; (4) The discharge module includes: a second discharge module 151 and a third discharge module 152.

[0079] It should be noted that when the three-phase power conversion circuit includes the first half bus load and the second half bus load at the same time, the selection priorities of the third and fourth types are the same.

[0080] In some embodiments, the three-phase power conversion circuit further includes a full bus load 17, and the positive and negative DC output terminals are connected in parallel to the full bus load 17. Figure 5 shown.

[0081] In some embodiments, the first capacitor C1 can also be connected to the lower bus as the lower bus capacitor, and the second capacitor C2 can also be connected to the upper bus as the upper bus capacitor, that is, the bus terminal is sequentially connected to the negative bus terminal through the second capacitor C2 and the first capacitor C1. As Figure 6 shown, the first half-bus load 14 is connected in parallel across the two ends of the first capacitor 12 as the lower bus load. And Figures 1 to 5 the positions of the first capacitor and the second capacitor in can be swapped, that is, the first capacitor C1 is the lower bus capacitor and the second capacitor C2 is the upper bus capacitor. It should be understood that the terms first, second, third, etc. are used to describe various information, but this information should not be limited to these terms.

[0082] Exemplarily, the above three-phase power conversion circuit is applied to an air conditioner. The half-bus load can be a DC fan and is powered by rectifying an independent phase voltage. The full-bus load can be a DC compressor and is connected to the high-voltage DC bus voltage. In one embodiment, the DC fan is the load of the lower bus capacitor of the air conditioner.

[0083] In some embodiments, the discharge module includes a power switch tube and a power-consuming device connected in series with each other (as Figure 7 shown); the power-consuming device is controlled to work by controlling the on / off of the power switch tube, and when the power-consuming device works, the discharge module is in the discharge state.

[0084] In practical applications, the power-consuming device can be any one or more power-consuming devices in the air conditioner. When multiple power-consuming devices are included, the multiple power-consuming devices are connected in series or in parallel.

[0085] Exemplarily, the power switch tube includes one of a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), an Insulated Gate Bipolar Transistor (IGBT), a triode, and a thyristor; the power-consuming device includes at least one of a resistor, a motor, and a compressor. As Figure 8 shown, the power-consuming device is a resistor. As Fig. 9 shown, the power-consuming device is a motor or a compressor.

[0086] Figures 7 to 9 In, terminal 1 and terminal 2 are the two ends of the discharge module, and 3 is the control terminal of the power switch tube.

[0087] As Fig.10 shown, the three-phase power conversion circuit of the present application further includes: a controller 18,

[0088] The controller 18 is connected to the control end of the power switch tube, and is used to adjust the duty cycle of the power switch tube when the voltage of the first capacitor and / or the voltage of the second capacitor is greater than a voltage threshold, and control the power switch tube to be in a closed state so that the power-consuming device works.

[0089] Fig.10 The fan load is powered by the lower bus capacitor C2, the discharge module is powered by the upper bus capacitor C1, and the compressor load is powered by the full bus capacitor. When the voltage of C1 rises above the maximum withstand voltage of C1 (i.e., the first voltage threshold corresponding to C1), the discharge module is in a discharge state, thereby lowering the voltage of C1.

[0090] Fig.10 The middle full bus load includes a power switch tube (i.e., an intelligent power module (IPM1) and a compressor, and the first half bus load includes a power switch tube (i.e., IPM2) and a fan. The controller is also connected to the control ends of IPM1 and IPM2, and controls the start and shut down of the fan and the compressor by controlling IPM1 and IPM2.

[0091] In actual applications, the controller 18 is also connected to the control ends of the IGBT modules T1 to T6, and is used to calculate the duty cycle of each phase power switch tube (such as the IGBT module) based on the upper bus capacitor voltage value U1, the lower bus capacitor voltage U2, the phase current Iabc, the phase voltage Uabc, the full bus reference voltage Udcref, and the lower bus capacitor reference voltage U1ref (or the upper bus capacitor reference voltage U2ref), thereby controlling the action of the three-phase switch.

[0092] like Fig.11 As shown, the fan load is powered by the lower bus capacitor C2, the compressor load is powered by the full bus capacitor, or there is no compressor load, and the discharge module (i.e., the third discharge module) is powered by the full bus capacitor. When the voltage of C1 rises above the maximum withstand voltage of C1 (i.e., the first voltage threshold corresponding to C1), the discharge module is in a discharge state, thereby lowering the voltage of C1.

[0093] In some embodiments, at least one mapping relationship between a voltage range and a duty cycle can be pre-set, and the target voltage range in which the target capacitor voltage is located can be determined according to the pre-set at least one voltage range; and the target duty cycle corresponding to the target voltage range can be determined according to the mapping relationship. In this way, the duty cycle can be flexibly set according to the degree of capacitor voltage rise, with a higher voltage rise corresponding to a higher duty cycle and a lower voltage rise corresponding to a lower duty cycle, thereby improving the control accuracy of the discharge module.

[0094] By adopting the above-mentioned three-phase power conversion circuit and configuring a discharge module for the second capacitor not connected to the load, a discharge operation can be performed when the voltage of the second capacitor rises, thereby reducing the voltage of the second capacitor, avoiding overvoltage problems when the half-bus load operates alone, and ensuring the safe operation of the half-bus load.

[0095] The embodiment of the present application further provides a household appliance, comprising: any one of the above three-phase power conversion circuits. The household appliance may be an air conditioner, a refrigerator or other equipment.

[0096] Based on any of the above three-phase power conversion circuits, the embodiment of the present application further provides a control method for a three-phase power conversion circuit, wherein the three-phase power conversion circuit is any of the three-phase power conversion circuits in the embodiment of the present application, such as Fig.12 As shown, the method includes:

[0097] Step 1201: Obtain a target capacitor voltage; wherein the target capacitor is a first capacitor and / or a second capacitor in the three-phase power conversion circuit;

[0098] Step 1202: The target capacitor voltage is greater than or equal to a first voltage threshold, and a start control signal is generated;

[0099] Here, if the target capacitor voltage is less than the first voltage threshold, the target capacitor voltage continues to be monitored.

[0100] In some embodiments, the target capacitor is the first capacitor or the second capacitor in the three-phase power conversion circuit that is not connected to a half-bus load; when the target capacitor is the first capacitor, the first capacitor threshold is set according to the withstand voltage value of the first capacitor, or the upper limit value of the full bus voltage; when the target capacitor is the second capacitor, the first capacitor threshold is set according to the withstand voltage value of the second capacitor, or the upper limit value of the full bus voltage.

[0101] It should be noted that the full bus in the embodiment of the present application refers to the positive and negative busbars ( Figure 1 Between point P and point N) is included in the high-voltage DC bus filter circuit using two-stage capacitors in series. The midpoint of the two-stage capacitors in series ( Figure 1 Point O) and positive busbar ( Figure 1 The upper busbar is between the middle point of the two-stage capacitor and the negative busbar ( Figure 1 The middle point of the first capacitor C1 and the second capacitor C2 is the lower half bus, and the upper half bus and the lower half bus are both half bus. Exemplarily, the middle point of the first capacitor C1 and the second capacitor C2 connected in series and the positive bus terminal is the upper half bus, and the middle point of the first capacitor C1 and the second capacitor C2 connected in series and the negative bus terminal is the lower half bus.

[0102] It should be noted that Figure 1The first capacitor C1 is the upper bus capacitor, the first half bus load is the upper bus load, and the second capacitor C2 is the lower bus capacitor. Figure 1 It is not used to limit the connection position of the capacitors in the present application. In the embodiment of the present application, the first capacitor C1 can also be connected to the lower bus as a lower bus capacitor, and the second capacitor C2 can also be connected to the upper bus as an upper bus capacitor, that is, the bus end is connected to the negative bus end through the second capacitor C2 and the first capacitor C1 in sequence.

[0103] That is to say, when monitoring the target capacitor voltage, the upper bus capacitor reference voltage U1ref and the upper bus capacitor actual voltage U1 can be compared to determine whether the upper bus capacitor is over-voltage, and the lower bus capacitor reference voltage U2ref and the lower bus capacitor actual voltage U2 can be compared to determine whether the lower bus capacitor is over-voltage, thereby controlling the discharge module.

[0104] When the lower half bus has a half bus load (which can be understood as the second capacitor being connected in parallel with the second half bus load), the actual voltage U1 of the upper bus capacitor and the upper and lower limits of the upper bus capacitor voltage (or the upper and lower limits of the target full bus voltage) can be compared to control the discharge module.

[0105] Similarly, when the upper half bus has a half bus load (which can be understood as the first capacitor being connected in parallel with the first half bus load), the actual voltage U2 of the lower bus capacitor and the upper and lower limits of the lower bus capacitor voltage (or the upper and lower limits of the target full bus voltage) can be compared to control the discharge module.

[0106] Here, the start control signal is used to control the discharge module to be in a discharge state.

[0107] In some embodiments, the discharge module includes a power switch tube and a power consumption device connected in series;

[0108] The target capacitor voltage is greater than or equal to a first voltage threshold, and a start control signal is generated, comprising:

[0109] The target capacitor voltage is greater than or equal to the first voltage threshold, and the duty cycle of the switch module of the discharge module is set according to the voltage range of the target capacitor voltage to generate the start control signal;

[0110] The step of controlling the discharge module to operate in a discharge state according to the start control signal includes:

[0111] According to the start control signal, the power switch tube is controlled to be in a closed state.

[0112] That is to say, the switch duty cycle of the discharge module is calculated by the reference voltage and the actual value of the half-bus capacitor not connected to the half-bus load, thereby controlling the on-off of the switch of the discharge circuit.

[0113] Exemplarily, when the voltage of the half-bus capacitor not connected to the half-bus load exceeds the upper limit of the reference voltage, the switch duty cycle of the discharge module is calculated by the reference voltage and actual value of the half-bus capacitor not connected to the half-bus load, thereby controlling the on and off of the switch of the discharge circuit until the capacitor voltage is less than the lower limit of the reference voltage.

[0114] Alternatively, when the voltage of the half-bus capacitor not connected to the half-bus load exceeds the upper limit of the reference voltage, the on-off of the switch of the discharge circuit is controlled by a preset duty cycle.

[0115] Step 1203: According to the start control signal, control the discharge module to operate in a discharge state to control the target capacitor voltage to be reduced to less than a second voltage threshold; wherein the first voltage threshold is greater than or equal to the second voltage threshold.

[0116] That is to say, the discharge module is used to provide overvoltage protection for the half-bus capacitor.

[0117] In some embodiments, the three-phase power conversion circuit also includes a full bus load, and the positive and negative DC output terminals are connected in parallel with the full bus load; the method also includes: when the full bus load is turned on and the first half bus load is turned off, controlling the discharge circuit to be in a closed state, or controlling the discharge circuit to be in a low-power working state.

[0118] Here, when the full bus load is turned on and the half bus load is turned off, the discharge loop is turned off or its power is adjusted to the lowest state to reduce the power consumption of the system.

[0119] In practical applications, when the full bus load is on, the half bus load is on, the ratio of the full bus load power to the half bus load is lower than the value K1, or when the full bus load is off and the half bus load is working, the duty cycle of the power switch of the discharge circuit can be calculated based on the actual voltage U1 of the upper bus capacitor (or the actual voltage U2 of the lower bus capacitor).

[0120] In some embodiments, when the full bus load is determined to be turned on and the power is sufficient, the full bus load can be used to replace the discharge module to control the voltage of the half bus capacitor that is not connected to the half bus load.

[0121] The step of setting the duty cycle of the switch module of the discharge module according to the voltage range of the target capacitor voltage includes:

[0122] Determining a target voltage range in which the target capacitor voltage is located according to at least one preset voltage range;

[0123] According to the mapping relationship between the voltage range and the duty cycle, a target duty cycle corresponding to the target voltage range is determined.

[0124] In some embodiments, any of the above control methods can be specifically applied when the first half-bus load is turned on, the full bus load is turned on, and the ratio of the full bus load to the first half-bus load is lower than a preset ratio, or when the first half-bus load is turned on and the full bus load is turned off.

[0125] Here, the execution subject of step 1201 to step 1203 may be a processor of the controller.

[0126] Below Figure 2 and Figure 3 This three-phase power conversion circuit is used as an example to illustrate the control method. At this time, the upper bus capacitor is connected to the load, and the lower bus capacitor is not connected to the load. When the upper bus load is running, the voltage of the lower bus capacitor rises, such as Fig.13 As shown, the control method may specifically include:

[0127] Step 1301: Obtain the lower bus capacitor voltage;

[0128] Step 1302: Is the lower bus capacitor voltage greater than or equal to the first voltage threshold? If yes, execute step 1303; if no, return to step 1301;

[0129] Here, the first voltage threshold may be determined according to the withstand voltage value of the upper bus capacitor, or according to the maximum voltage value of the full bus voltage value, or a preset default value.

[0130] Step 1303: Generate a start control signal and control the discharge module to operate in a discharge state.

[0131] It should be noted that the upper bus capacitor is not connected to a load, and the lower bus capacitor is connected to a load. When the lower bus load is running, the voltage of the lower bus capacitor rises. Step 1301 is replaced by obtaining the voltage of the upper bus capacitor, and step 1302 is replaced by determining whether the voltage of the upper bus capacitor is greater than or equal to a first voltage threshold. The first voltage threshold at this time can be determined according to the withstand voltage value of the upper bus capacitor, or according to the maximum voltage value of the full bus voltage value, or a preset default value.

[0132] It should be noted that the discharge module can also be replaced by a third discharge module connected in parallel with the positive and negative DC output terminals. The third discharge module can provide overvoltage protection for capacitors not connected to a load, and can also provide overvoltage protection for capacitors connected to a load at the other terminal.

[0133] To implement the method of the embodiment of the present application, based on the same inventive concept, the embodiment of the present application also provides a control device for a three-phase power conversion circuit, the control device is used to control any three-phase power conversion circuit in the embodiment of the present application to realize power supply voltage conversion, such as Fig.14As shown, the control device includes: a processor 1401 and a memory 1402 configured to store a computer program that can be run on the processor;

[0134] The processor 1401 is configured to execute the method steps in the aforementioned embodiment when running a computer program.

[0135] Of course, in practical applications, Fig.14 As shown, the various components in the device are coupled together via a bus system 1403. It is understood that the bus system 1403 is used to realize the connection and communication between these components. In addition to the data bus, the bus system 1403 also includes a power bus, a control bus, and a status signal bus. However, for the sake of clarity, Fig.14 Various buses are labeled as bus system 1403.

[0136] In practical applications, the processor may be at least one of an application-specific integrated circuit (ASIC), a digital signal processing device (DSPD), a programmable logic device (PLD), a field-programmable gate array (FPGA), a controller, a microcontroller, and a microprocessor. It is understandable that for different devices, the electronic device used to implement the functions of the processor may also be other, and the embodiments of the present application do not specifically limit this.

[0137] The above-mentioned memory can be a volatile memory (volatile memory), such as a random access memory (RAM); or a non-volatile memory (non-volatile memory), such as a read-only memory (ROM), a flash memory, a hard disk (HDD) or a solid-state drive (SSD); or a combination of the above-mentioned types of memory, and provide instructions and data to the processor.

[0138] The device can be applied to household electrical appliances equipped with the above-mentioned three-phase power conversion circuit, such as air conditioners, refrigerators and other equipment.

[0139] In an exemplary embodiment, the embodiment of the present application also provides a computer-readable storage medium, such as a memory including a computer program, and the computer program can be executed by a processor of a household appliance to complete the steps of the control method of the aforementioned three-phase power conversion circuit.

[0140] It should be understood that the terms used in the present application are only for the purpose of describing specific embodiments, but are not intended to limit the present application. The singular forms of "a", "said" and "the" used in the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used in this article refers to and includes any or all possible combinations of one or more associated listed items. The expressions "having", "may have", "include" and "include", or "may include" and "may include" in this application can be used to indicate the presence of corresponding features (e.g., elements such as numerical values, functions, operations or components), but the presence of additional features is not excluded.

[0141] It should be understood that although the terms first, second, third, etc. may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other and are not necessarily used to describe a specific order or sequence. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information.

[0142] The technical solutions described in the embodiments of the present application can be combined arbitrarily without conflict.

[0143] In the several embodiments provided in the present application, it should be understood that the disclosed methods, devices and equipment can be implemented in other ways. The embodiments described above are only schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.

[0144] The units described above as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0145] In addition, all functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may be a separate unit, or two or more units may be integrated into one unit; the above-mentioned integrated units may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0146] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A three-phase power conversion circuit, characterized in that, it includes: a three-phase power source, a power rectification module, a first capacitor, a second capacitor, a first half-bus load, and a discharge module; wherein, the three-phase AC input terminals of the power rectification module are connected to the three-phase power source, and the positive and negative DC output terminals are connected in parallel with the first capacitor and the second capacitor connected in series with each other; both ends of the first capacitor are connected in parallel with the first half-bus load, the discharge module includes any two of: a first discharge module connected in parallel across the first capacitor, a second discharge module connected in parallel across the second capacitor, and a third discharge module connected in parallel across the positive and negative DC output terminals; the discharge module is used to control the discharge module to operate in a discharge state when the voltage of the first capacitor and / or the second capacitor is greater than or equal to a first voltage threshold, so as to control the voltage of the first capacitor and / or the second capacitor to drop below a second voltage threshold; wherein, the first voltage threshold is greater than or equal to the second voltage threshold.

2. The three-phase power conversion circuit according to claim 1, characterized in that, the discharge module further includes a first discharge module connected in parallel across the first capacitor.

3. The three-phase power conversion circuit according to claim 1, characterized in that, the three-phase power conversion circuit further includes a second half-bus load, and both ends of the second capacitor are connected in parallel with the second half-bus load; the discharge module includes: a third discharge module connected in parallel across the positive and negative DC output terminals.

4. The three-phase power conversion circuit according to claim 1, characterized in that, the three-phase power conversion circuit further includes a full-bus load, and the positive and negative DC output terminals are connected in parallel with the full-bus load.

5. The three-phase power conversion circuit according to claim 1, characterized in that, the power rectification module includes: a three-phase rectifier bridge and a bidirectional switch assembly, the three-phase rectifier bridge includes a first bridge arm, a second bridge arm, and a third bridge arm connected in parallel with each other; the bidirectional switch assembly includes a first bidirectional switch, a second bidirectional switch, and a third bidirectional switch. One end of the first bidirectional switch is connected to the midpoint of the first bridge arm, one end of the second bidirectional switch is connected to the midpoint of the second bridge arm, and one end of the third bidirectional switch is connected to the midpoint of the third bridge arm; the other ends of the first bidirectional switch, the second bidirectional switch, and the third bidirectional switch are all connected to the common terminal between the first capacitor and the second capacitor.

6. The three-phase power conversion circuit according to any one of claims 1-5, characterized in that, the three-phase power conversion circuit further includes: a controller, and the discharge module includes a power switch tube and a power-consuming device connected in series; the controller is connected to the control terminal of the power switch tube, and is used to adjust the duty cycle of the power switch tube and control the power switch tube to be in a closed state when the voltage of the first capacitor and / or the voltage of the second capacitor is greater than a voltage threshold, so that the power-consuming device works.

7. The three-phase power conversion circuit according to claim 6, characterized in that, The power switch tube includes one of a metal-oxide semiconductor field effect transistor, an insulated gate bipolar transistor, a triode, and a thyristor; The power-consuming device includes at least one of a resistor, a motor, and a compressor.

8. An appliance device, characterized in that, the appliance device includes the three-phase power conversion circuit according to any one of claims 1-7.

9. A control method for a three-phase power conversion circuit, characterized in that, the three-phase power conversion circuit includes the three-phase power conversion circuit according to any one of claims 1-7; the method includes: Obtaining a target capacitor voltage; wherein, the target capacitor is the first capacitor and / or the second capacitor in the three-phase power conversion circuit, when the target capacitor voltage is greater than or equal to a first voltage threshold, generating a start control signal; According to the start control signal, controlling the discharge module to work in a discharge state to control the target capacitor voltage to drop below a second voltage threshold; wherein, the first voltage threshold is greater than or equal to the second voltage threshold.

10. The method according to claim 9, characterized in that, the discharge module includes a power switch tube and a power-consuming device connected in series; when the target capacitor voltage is greater than or equal to a first voltage threshold, generating a start control signal, including: when the target capacitor voltage is greater than or equal to the first voltage threshold, setting the duty ratio of the switch module of the discharge module according to the voltage range where the target capacitor voltage is located, and generating the start control signal; according to the start control signal, controlling the discharge module to work in a discharge state, including: According to the start control signal, controlling the power switch tube to be in a closed state.

11. The method according to claim 9, characterized in that, the target capacitor is the first capacitor or the second capacitor in the three-phase power conversion circuit that is not connected to a half-bus load; when the target capacitor is the first capacitor, the first capacitor threshold is set according to the withstand voltage value of the first capacitor or the upper limit value of the full-bus voltage; when the target capacitor is the second capacitor, the first capacitor threshold is set according to the withstand voltage value of the second capacitor or the upper limit value of the full-bus voltage.

12. The method according to claim 9, characterized in that, the three-phase power conversion circuit further includes a full-bus load, and the positive and negative DC output terminals are connected in parallel with the full-bus load; the method further includes: when the full-bus load is turned on and the first half-bus load is turned off, controlling the discharge module to be in a closed state or controlling the discharge module to be in a low-power working state.

13. A control device for a three-phase power conversion circuit, characterized in that, the control device includes: a processor and a memory configured to store a computer program that can run on the processor, wherein, when the processor is configured to run the computer program, it executes the steps of the method according to any one of claims 9 to 12.

14. A computer-readable storage medium, on which a computer program is stored, characterized in that, when the computer program is executed by a processor, it implements the steps of the method according to any one of claims 9 to 12.

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