Motor driving circuit, motor and electrical equipment

Abstract

The utility model discloses a motor drive circuit, a motor and electrical equipment, the drive circuit comprises a first voltage conversion circuit, the input end of the first voltage conversion circuit is connected with an alternating current power supply, and the first voltage conversion circuit is configured to convert first alternating current provided by the alternating current power supply into first direct current; the input end of the second voltage conversion circuit is connected with the output end of the first voltage conversion circuit, and the second voltage conversion circuit is configured to convert the first direct current into second direct current; the pre-charging circuit is arranged at the output end or the input end of the first voltage conversion circuit and is configured to pre-charge the second voltage conversion circuit; the input end of the third voltage conversion circuit is connected with the output end of the second voltage conversion circuit, the output end of the third voltage conversion circuit is connected with the motor, and the third voltage conversion circuit is configured to convert the second direct current into second alternating current to be provided for the motor. The driving circuit is wider in applicable input voltage range and higher in applicability.

Description

Technical Field

[0001] The utility model relates to the field of drive circuits, in particular to a motor drive circuit and a motor and electrical equipment. Background Art

[0002] In the design of various motor drive solutions, the withstand voltage of the switching device is one of the important indicators. The drive solution usually leaves a higher derating space to ensure the safe operation of the drive circuit. For example, the current IPM (Intelligent Power Module) and PIM (Power Integrated Module) drive solutions on the market usually use switching devices with a withstand voltage of 1200V to form the drive circuit to meet the safety requirements of most motors. However, these drive solutions are limited by the withstand voltage problem and the applicable input voltage scenarios are limited. For example, when facing higher voltage AC, such as 575V three-phase AC, the maximum voltage value of the bus voltage in the motor drive circuit can reach 976V, and the derating of the withstand voltage of 1200V is obviously low, which is prone to safety problems, making these drive solutions not very applicable. Utility Model Content

[0003] The utility model aims to solve one of the technical problems in the related art to at least a certain extent. To this end, the first purpose of the utility model is to propose a motor drive circuit, by setting a second voltage conversion circuit in the motor drive circuit to convert the first direct current input by the first voltage conversion circuit into a second direct current, and provide it to a third voltage conversion circuit, so that the bus voltage of the motor drive circuit is not affected by the AC power supply voltage, thereby making the input voltage range applicable to the motor drive circuit wider, and at the same time, by setting a pre-charging circuit in the motor drive circuit to pre-charge the second voltage conversion circuit, the possible oscillation current problem is avoided, thereby improving the applicability and safety of the motor drive circuit.

[0004] The second objective of the present invention is to provide a motor.

[0005] The third objective of the present invention is to provide an electrical device.

[0006] To achieve the above-mentioned purpose, the first embodiment of the utility model proposes a motor drive circuit, including: a first voltage conversion circuit, the input end of the first voltage conversion circuit is connected to an AC power supply, and is configured to convert a first AC power provided by the AC power supply into a first DC power; a second voltage conversion circuit, the input end of the second voltage conversion circuit is connected to the output end of the first voltage conversion circuit, and is configured to convert a first DC power into a second DC power; a pre-charging circuit, the pre-charging circuit is arranged at the output end or the input end of the first voltage conversion circuit, and is configured to pre-charge the second voltage conversion circuit; a third voltage conversion circuit, the input end of the third voltage conversion circuit is connected to the output end of the second voltage conversion circuit, the output end of the third voltage conversion circuit is connected to the motor, and is configured to convert the second DC power into a second AC power and provide it to the motor.

[0007] According to the motor drive circuit of the embodiment of the utility model, a second voltage conversion circuit is provided in the motor drive circuit to convert the first direct current input by the first voltage conversion circuit into a second direct current and provide it to the third voltage conversion circuit, so that the bus voltage of the motor drive circuit is not affected by the AC power supply voltage, thereby making the applicable input voltage range of the motor drive circuit wider. At the same time, a pre-charging circuit is provided in the motor drive circuit to pre-charge the second voltage conversion circuit, thereby avoiding possible oscillation current problems, thereby improving the applicability and safety of the motor drive circuit.

[0008] According to an embodiment of the present utility model, the first voltage conversion circuit is a three-phase uncontrolled rectifier circuit or a three-phase controlled rectifier circuit.

[0009] According to one embodiment of the utility model, the pre-charging circuit includes: a first pre-charging switch and a first pre-charging resistor, the first pre-charging switch is connected in series between the output end of the first voltage conversion circuit and the input end of the second voltage conversion circuit, and the first pre-charging resistor is connected in parallel with the first pre-charging switch.

[0010] According to one embodiment of the utility model, the AC power supply is a three-phase power supply, and the pre-charging circuit includes: a second pre-charging switch and a second pre-charging resistor, one end of the second pre-charging switch is connected to a one-phase input end of the AC power supply, the other end of the second pre-charging switch is connected to one end of the second pre-charging resistor, and the other end of the second pre-charging resistor is connected to the first input end of the first voltage conversion circuit; a third pre-charging switch, one end of the third pre-charging switch is connected to one end of the second pre-charging switch, and the other end of the third pre-charging switch is connected to the other end of the second pre-charging resistor; a fourth pre-charging switch, the fourth pre-charging switch is connected in series between the other phase input end of the AC power supply and the second input end of the first voltage conversion circuit.

[0011] According to one embodiment of the utility model, the second voltage conversion circuit includes: a first capacitor, a first controllable switch, a first diode and a first inductor, wherein one end of the first capacitor is connected to one end of the pre-charging circuit, the other end of the first capacitor is connected to the second output end of the first voltage conversion circuit, and the first output end of the first voltage conversion circuit is also connected to the other end of the pre-charging circuit; the first end of the first controllable switch is connected to one end of the first capacitor, and the second end of the first controllable switch is respectively connected to the cathode of the first diode and one end of the first inductor; the other end of the first inductor is connected to the first input end of the third voltage conversion circuit; the anode of the first diode is respectively connected to the other end of the first capacitor and the second input end of the third voltage conversion circuit.

[0012] According to one embodiment of the utility model, the third voltage conversion circuit includes: a second capacitor and a three-phase inverter circuit, wherein one end of the second capacitor is respectively connected to the first output end of the second voltage conversion circuit and the first input end of the three-phase inverter circuit, the other end of the second capacitor is respectively connected to the second output end of the second voltage conversion circuit and the second input end of the three-phase inverter circuit, and the output end of the three-phase inverter circuit is connected to the motor.

[0013] According to one embodiment of the utility model, the second voltage conversion circuit includes: a third capacitor, a fourth capacitor, a second controllable switch, a third controllable switch, a second diode, a third diode, a second inductor, a third inductor and a fifth capacitor, wherein one end of the third capacitor is connected to one end of the pre-charging circuit, the other end of the third capacitor is connected to one end of the fourth capacitor, the other end of the fourth capacitor is connected to the second output end of the first voltage conversion circuit, and the first output end of the first voltage conversion circuit is also connected to the other end of the pre-charging circuit; the first end of the second controllable switch is connected to one end of the third capacitor, and the second end of the second controllable switch is respectively connected to the cathode of the second diode and one end of the second inductor; the first end of the third controllable switch is connected to the other end of the fourth capacitor, the second end of the third controllable switch is respectively connected to the anode of the third diode and one end of the third inductor, and the cathode of the third diode is respectively connected to the anode of the second diode, the other end of the third capacitor and one end of the fourth capacitor; the other end of the second inductor is respectively connected to the first input end of the third voltage conversion circuit and one end of the fifth capacitor, and the other end of the fifth capacitor is connected to the other end of the third inductor.

[0014] According to an embodiment of the present invention, the third voltage conversion circuit includes a three-phase inverter circuit.

[0015] According to one embodiment of the present invention, the voltage of the first alternating current is 575V, 460V or 380V.

[0016] In order to achieve the above-mentioned object, a second embodiment of the present invention provides a motor, including the above-mentioned motor drive circuit.

[0017] According to the motor of the embodiment of the utility model, through the aforementioned motor driving circuit, the electrical equipment can be powered by a wide range of AC power, thereby improving the applicability of the motor and also improving the safety of the motor.

[0018] In order to achieve the above-mentioned purpose, a third aspect of the present invention provides an electrical device, including the aforementioned motor drive circuit, or the aforementioned motor.

[0019] According to the electrical equipment of the embodiment of the utility model, the electrical equipment can be powered by a wide range of AC power through the aforementioned motor drive circuit or the aforementioned motor, thereby improving the applicability of the electrical equipment and also improving the safety of the electrical equipment.

[0020] Additional aspects and advantages of the present invention will be given in part in the following description and in part will become apparent from the following description or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of a motor driving circuit according to an embodiment of the utility model;

[0022] Figure 2 is a structural schematic diagram of a motor driving circuit according to another embodiment of the utility model;

[0023] Figure 3 is a circuit diagram of a motor drive circuit according to an embodiment of the utility model;

[0024] Figure 4 is a circuit diagram of a motor driving circuit according to another embodiment of the utility model;

[0025] Figure 5 It is a structural schematic diagram of a motor according to an embodiment of the utility model;

[0026] Figure 6a-6b The figure is a schematic diagram of the structure of an electrical device according to an embodiment of the utility model. DETAILED DESCRIPTION

[0027] The embodiments of the present invention are described in detail below, and examples of the embodiments 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.

[0028] The motor drive circuit, motor and electrical equipment provided in the embodiments of the present invention are described below with reference to the accompanying drawings.

[0029] Figure 1 is a schematic diagram of a motor drive circuit according to an embodiment of the present invention, referring to Figure 1 As shown, the motor driving circuit 100 includes: a first voltage conversion circuit 110 , a second voltage conversion circuit 120 , a pre-charging circuit 130 and a third voltage conversion circuit 140 .

[0030] Among them, the input end of the first voltage conversion circuit 110 is connected to the AC power supply VAC, and is configured to convert the first AC power provided by the AC power supply VAC into a first DC power; the input end of the second voltage conversion circuit 120 is connected to the output end of the first voltage conversion circuit 110, and is configured to convert the first DC power into a second DC power; the pre-charging circuit 130 is provided at the output end of the first voltage conversion circuit 110, and is configured to pre-charge the second voltage conversion circuit 120; the input end of the third voltage conversion circuit 140 is connected to the output end of the second voltage conversion circuit 120, and the output end of the third voltage conversion circuit 140 is connected to the motor M, and is configured to convert the second DC power into a second AC power and provide it to the motor M.

[0031] Specifically, the first voltage conversion circuit 110 can convert the first alternating current inputted from the alternating current power source VAC into a first direct current, and input the first direct current into the second voltage conversion circuit 120. The second voltage conversion circuit 120 can perform step-up and step-down processing on the first direct current, convert the first direct current into a second direct current, and provide it to the third voltage conversion circuit 130. The third voltage conversion circuit 130 can convert the second direct current into a second alternating current and provide it to the motor M to drive the motor M to operate.

[0032] In the motor drive scheme of the related art, taking the PIM drive scheme as an example, the PIM drive scheme usually includes a topology of a rectifier bridge + PFC circuit + three-phase inverter circuit. In this topology, the bus voltage can reach up to 1.7 times the three-phase input voltage. Taking the 575v AC power supply voltage as an example, the theoretical maximum value of the bus voltage is 575*1.414*1.2=976V. The PIM drive scheme usually uses a switch device with a withstand voltage of 1200v. If it is used in a scenario where 575v three-phase AC is used as the AC power input, the derating is obviously low and the safe operation of the drive circuit cannot be ensured. Therefore, the PIM drive scheme is applicable to limited voltage scenarios and has poor applicability. If the above-mentioned PIM drive scheme chooses to increase the withstand voltage of the switch device, for example, when a switch tube with a withstand voltage of 1700v is selected as the switch device, the cost of the motor drive circuit will increase significantly, making the drive circuit less cost-effective. In the motor drive circuit 100 of the embodiment of the utility model, a second voltage conversion circuit 120 is provided. The second voltage conversion circuit 120 can convert the first DC power with uncertain input voltage into the second DC power with stable voltage. For example, the voltage of the second DC power can be about 400V, so that the bus voltage of the motor drive circuit 100 is not affected by the voltage of the AC power supply VAC, thereby making the motor drive circuit 100 with a fixed withstand voltage switch device applicable to a wider input voltage range, wherein the bus voltage of the motor drive circuit 100 refers to the voltage on the bus capacitor of the third voltage conversion circuit 140. For example, a switch device with a withstand voltage of 1200V can be applied to a variety of scenarios where the voltage of the AC power supply VAC is 380V, 460V or 575V, thereby improving the applicability of the motor drive circuit 100.

[0033] In addition, reference Figure 1 As shown, since the first voltage conversion circuit 110 and the second voltage conversion circuit 120 have bus capacitors to stabilize the voltage of the first direct current, and the bus capacitors are prone to generate oscillating currents when powered on, causing circuit damage. Therefore, the motor drive circuit 100 also has a pre-charging circuit 130. The pre-charging circuit 130 can pre-charge the second voltage conversion circuit 120 when the motor drive circuit 100 is powered on, so as to avoid the bus capacitors from generating large oscillating currents when the motor drive circuit 100 is powered on, so as to improve the safety of the motor drive circuit 100.

[0034] It should be noted that the reference Figure 2 As shown, the pre-charging circuit 130 can also be set at the input end of the first voltage conversion circuit 110. At this time, the pre-charging circuit 130 can also pre-charge the second voltage conversion circuit 120 to avoid the bus capacitor from generating a large oscillating current when the motor drive circuit 100 is powered on, thereby improving the safety of the motor drive circuit 100.

[0035] In the above embodiment, a second voltage conversion circuit is provided in the motor drive circuit to convert the first direct current input by the first voltage conversion circuit into a second direct current and provide it to the third voltage conversion circuit, so that the bus voltage of the motor drive circuit is not affected by the AC power supply voltage, thereby making the applicable input voltage range of the motor drive circuit wider. At the same time, a pre-charging circuit is provided in the motor drive circuit to pre-charge the second voltage conversion circuit, thereby avoiding possible oscillation current problems, thereby improving the applicability and safety of the motor drive circuit.

[0036] In some embodiments, the first voltage conversion circuit 110 can be a plurality of types of rectifier circuits, such as a three-phase controlled rectifier circuit or a three-phase uncontrolled rectifier circuit, etc., which can be determined according to actual needs and is not limited here. Figure 3 As shown, the first voltage conversion circuit 110 may include a three-phase uncontrolled rectifier circuit composed of six rectifier diodes (VD1-VD6), and the specific rectification principle is not expanded here. In addition, since the cost of diodes is relatively low, the first voltage conversion circuit 110 at this time also has a cost advantage.

[0037] In some embodiments, reference Figure 3 As shown, the pre-charging circuit 130 includes: a first pre-charging switch K1 and a first pre-charging resistor R1, the first pre-charging switch K1 is connected in series between the output end of the first voltage conversion circuit 110 and the input end of the second voltage conversion circuit 120, and the first pre-charging resistor R1 is connected in parallel with the first pre-charging switch K1.

[0038] Specifically, when the motor drive circuit 100 is powered on, the first pre-charge switch K1 is in the off state, and the AC power supply VAC pre-charges the bus capacitor in the second voltage conversion circuit 120 through the first voltage conversion circuit 110 and the first pre-charge resistor R1, wherein the first pre-charge resistor R1 can limit the current to ensure circuit safety. After the pre-charge is completed, the first pre-charge switch K1 is closed to short-circuit the first pre-charge resistor R1 to avoid the first pre-charge resistor R1 generating additional power consumption and reducing the overall efficiency of the motor drive circuit 100, thereby realizing the pre-charge function for the second voltage conversion circuit 120.

[0039] In other embodiments, reference Figure 4As shown, the AC power supply VAC is a three-phase power supply, and the pre-charging circuit 130 includes: a second pre-charging switch K2, a second pre-charging resistor R2, a third pre-charging switch K3 and a fourth pre-charging switch K4. Among them, one end of the second pre-charging switch K2 is connected to a one-phase input end of the AC power supply VAC, the other end of the second pre-charging switch K2 is connected to one end of the second pre-charging resistor R2, and the other end of the second pre-charging resistor R2 is connected to the first input end of the first voltage conversion circuit 110; one end of the third pre-charging switch K3 is connected to one end of the second pre-charging switch K2, and the other end of the third pre-charging switch K3 is connected to the other end of the second pre-charging resistor R2; the fourth pre-charging switch K4 is connected in series between the other phase input end of the AC power supply VAC and the second input end of the first voltage conversion circuit 110.

[0040] Specifically, refer to Figure 4 As shown, the three-phase AC power supply may include three-phase input terminals A, B, and C, wherein the A-phase input terminal is connected to one end of the second pre-charging switch K2 and one end of the third pre-charging switch K3, and the B-phase input terminal is connected to the fourth pre-charging switch K4. When the motor drive circuit 100 is powered on, the third pre-charging switch K3 and the fourth pre-charging switch K4 are disconnected, and the second pre-charging switch K2 is closed. At this time, the A-phase input terminal and the C-phase input terminal of the AC power supply are connected to the first voltage conversion circuit 110, so as to input the AC power limited by the second pre-charging resistor R2 to the first input terminal of the first voltage conversion circuit 110 through the second pre-charging switch K2 and the second pre-charging resistor R2, thereby pre-charging the bus capacitor in the second voltage conversion circuit 120 to avoid generating an oscillating current. When the pre-charging is completed, the second pre-charging switch K2 is disconnected and the third pre-charging switch K3 is turned on, thereby avoiding the second pre-charging resistor R2 from generating additional power consumption and reducing the overall efficiency of the motor drive circuit 100, thereby realizing the pre-charging function for the second voltage conversion circuit 120.

[0041] In some embodiments, reference Figure 3 As shown, the second voltage conversion circuit 120 includes: a first capacitor C1, a first controllable switch Q1, a first diode D1 and a first inductor L1, wherein one end of the first capacitor C1 is connected to one end of the pre-charging circuit 130, the other end of the first capacitor C1 is connected to the second output end of the first voltage conversion circuit 110, and the first output end of the first voltage conversion circuit 110 is also connected to the other end of the pre-charging circuit 130; the first end of the first controllable switch Q1 is connected to one end of the first capacitor C1, and the second end of the first controllable switch Q1 is respectively connected to the cathode of the first diode D1 and one end of the first inductor L1; the other end of the first inductor L1 is connected to the first input end of the third voltage conversion circuit 140; the anode of the first diode D1 is respectively connected to the other end of the first capacitor C1 and the second input end of the third voltage conversion circuit 140.

[0042] Specifically, refer to Figure 3As shown, the first capacitor C1, the first controllable switch Q1, the first diode D1 and the first inductor L1 constitute a typical BUCK circuit. By controlling the conduction and closing of the first controllable switch Q1, the first DC power with a higher voltage can be converted into the second DC power with a lower voltage to achieve a step-down function, so that the motor drive circuit 100 using a fixed withstand voltage switch device can be applied to various high-voltage scenarios. For example, the motor drive circuit 100 using a 1200V withstand voltage switch device is applied in a 575V high-voltage scenario, thereby improving the applicability of the motor drive circuit 100. The specific principle of BUCK is not elaborated here.

[0043] Furthermore, the third voltage conversion circuit 140 includes: a second capacitor C2 and a three-phase inverter circuit 141, wherein one end of the second capacitor C2 is respectively connected to the first output end of the second voltage conversion circuit 120 and the first input end of the three-phase inverter circuit 141, the other end of the second capacitor C2 is respectively connected to the second output end of the second voltage conversion circuit 120 and the second input end of the three-phase inverter circuit 141, and the output end of the three-phase inverter circuit 141 is connected to the motor M.

[0044] Specifically, the second capacitor C2 is mainly used as a bus capacitor to suppress the voltage and current fluctuations of the second DC power. The three-phase inverter circuit 141 is mainly used to invert the second DC power into the second AC power, wherein, Figure 3 As shown, the three-phase inverter circuit 141 may include six switch tubes (VT1-VT6) with freewheeling diodes. The second direct current can be inverted into the second alternating current output by controlling the conduction timing of the six switch tubes (VT1-VT6). The specific principle will not be expanded here.

[0045] In other embodiments, reference Figure 4As shown, the second voltage conversion circuit 120 includes: a third capacitor C3, a fourth capacitor C4, a second controllable switch Q2, a third controllable switch Q3, a second diode D2, a third diode D3, a second inductor L2, a third inductor L3 and a fifth capacitor C5, wherein one end of the third capacitor C3 is connected to one end of the pre-charging circuit 130, the other end of the third capacitor C3 is connected to one end of the fourth capacitor C4, the other end of the fourth capacitor C4 is connected to the second output end of the first voltage conversion circuit 110, and the first output end of the first voltage conversion circuit 110 is also connected to the other end of the pre-charging circuit 130; the first end of the second controllable switch Q2 is connected to one end of the third capacitor C3. The first end of the third controllable switch Q3 is connected to the other end of the fourth capacitor C4, the second end of the third controllable switch Q3 is connected to the anode of the third diode D3 and one end of the third inductor L3, the cathode of the third diode D3 is connected to the anode of the second diode D2, the other end of the third capacitor C3 and one end of the fourth capacitor C4; the other end of the second inductor L2 is connected to the first input terminal of the third voltage conversion circuit 140 and one end of the fifth capacitor C5, and the other end of the fifth capacitor C5 is connected to the other end of the third inductor L3.

[0046] Furthermore, the third voltage conversion circuit 140 includes a three-phase inverter circuit 141 .

[0047] Specifically, refer to Figure 4 As shown, the third capacitor C3, the fourth capacitor C4, the second controllable switch Q2, the third controllable switch Q3, the second diode D2, the third diode D3, the second inductor L2, the third inductor L3 and the fifth capacitor C5 constitute a typical three-level topology DCDC buck circuit. At this time, compared with the BUCK circuit in the above embodiment, the three-level topology DCDC buck circuit in the embodiment of the utility model can not only realize the buck function of converting the first DC power with a higher voltage into the second DC power with a lower voltage. At the same time, since the voltage stress borne by the second controllable switch Q2 and the third controllable switch Q3 during the step-down process is half of the bus voltage, the input voltage of the AC power supply VAC can be further reduced. The voltage resistance value limit of the switch device of the motor drive circuit 100, thereby further improving the applicability of the second voltage conversion circuit. In addition, since the fifth capacitor C5 in the second voltage conversion circuit 120 can be used as a bus capacitor to suppress voltage fluctuations, the third voltage conversion circuit 140 can only include a three-phase inverter circuit 141 to avoid device duplication.

[0048] It should be noted that the first capacitor C1, the second capacitor C2 and the fifth capacitor C5 in the above-mentioned utility model embodiment may include multiple capacitors connected in series, and the manner of connecting multiple capacitors in series can reduce the voltage resistance limit of each capacitor, and then multiple capacitors with low voltage resistance values ​​can be selected to form the motor drive circuit 100, so as to reduce the hardware cost of the motor drive circuit 100. In addition, the first to third controllable switches in the above-mentioned embodiments can be different types of switch tubes, such as MOS tubes, triodes, etc., which are not limited here.

[0049] In summary, according to the motor drive circuit of the embodiment of the utility model, a second voltage conversion circuit is set in the motor drive circuit to convert the first direct current input by the first voltage conversion circuit into a second direct current, and provide it to the third voltage conversion circuit, so that the bus voltage of the motor drive circuit is not affected by the AC power supply voltage, thereby making the applicable input voltage range of the motor drive circuit wider. At the same time, a pre-charging circuit is set in the motor drive circuit to pre-charge the second voltage conversion circuit, thereby avoiding possible oscillation current problems, thereby improving the applicability and safety of the motor drive circuit.

[0050] Corresponding to the above embodiment, the utility model embodiment also provides a motor, referring to Figure 5 As shown, the motor 1000 includes the aforementioned motor driving circuit 100 .

[0051] According to the motor of the embodiment of the utility model, through the aforementioned motor driving circuit, the electrical equipment can be powered by a wide range of AC power, thereby improving the applicability of the motor and also improving the safety of the motor.

[0052] Corresponding to the above embodiment, the utility model embodiment also provides an electrical device, referring to Figure 6a or Figure 6b As shown, the electrical device 2000 includes the aforementioned motor drive circuit 100 , or the aforementioned motor 1000 .

[0053] According to the electrical equipment of the embodiment of the utility model, the aforementioned motor driving circuit enables the electrical equipment to accept power supply from a wide range of AC power sources, thereby improving the applicability of the motor and also improving the safety of the motor.

[0054] It should be understood that the various parts of the utility model can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiment, multiple 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.

[0055] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" 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 utility model. 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 can be combined in any one or more embodiments or examples in a suitable manner.

[0056] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0057] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A motor drive circuit, characterized in that: include: A first voltage conversion circuit, wherein an input end of the first voltage conversion circuit is connected to an AC power source and is configured to convert a first AC power provided by the AC power source into a first DC power; a second voltage conversion circuit, wherein an input end of the second voltage conversion circuit is connected to an output end of the first voltage conversion circuit and is configured to convert the first direct current into a second direct current; a pre-charging circuit, the pre-charging circuit being provided at an output end or an input end of the first voltage conversion circuit and being configured to pre-charge the second voltage conversion circuit; A third voltage conversion circuit, wherein the input end of the third voltage conversion circuit is connected to the output end of the second voltage conversion circuit, and the output end of the third voltage conversion circuit is connected to the motor, is configured to convert the second direct current into a second alternating current and provide it to the motor.

2. The motor drive circuit according to claim 1, characterized in that: The first voltage conversion circuit is a three-phase uncontrolled rectifier circuit or a three-phase controlled rectifier circuit.

3. The motor drive circuit according to claim 1, characterized in that: The pre-charge circuit comprises: A first pre-charge switch and a first pre-charge resistor, wherein the first pre-charge switch is connected in series between the output end of the first voltage conversion circuit and the input end of the second voltage conversion circuit, and the first pre-charge resistor is connected in parallel with the first pre-charge switch.

4. The motor drive circuit according to claim 1, characterized in that: The AC power supply is a three-phase power supply, and the pre-charging circuit comprises: a second pre-charging switch and a second pre-charging resistor, wherein one end of the second pre-charging switch is connected to a phase input end of the AC power supply, the other end of the second pre-charging switch is connected to one end of the second pre-charging resistor, and the other end of the second pre-charging resistor is connected to the first input end of the first voltage conversion circuit; a third pre-charging switch, one end of the third pre-charging switch being connected to one end of the second pre-charging switch, and the other end of the third pre-charging switch being connected to the other end of the second pre-charging resistor; A fourth pre-charge switch, wherein the fourth pre-charge switch is connected in series between another phase input terminal of the AC power supply and the second input terminal of the first voltage conversion circuit.

5. The motor drive circuit according to any one of claims 1 to 4, characterized in that: The second voltage conversion circuit includes: a first capacitor, a first controllable switch, a first diode and a first inductor, wherein: One end of the first capacitor is connected to one end of the pre-charging circuit, the other end of the first capacitor is connected to the second output end of the first voltage conversion circuit, and the first output end of the first voltage conversion circuit is also connected to the other end of the pre-charging circuit; A first end of the first controllable switch is connected to one end of the first capacitor, and a second end of the first controllable switch is connected to a cathode of the first diode and one end of the first inductor respectively; The other end of the first inductor is connected to the first input end of the third voltage conversion circuit; The anode of the first diode is connected to the other end of the first capacitor and the second input end of the third voltage conversion circuit respectively.

6. The motor drive circuit according to claim 5, characterized in that: The third voltage conversion circuit includes: a second capacitor and a three-phase inverter circuit, wherein one end of the second capacitor is respectively connected to the first output end of the second voltage conversion circuit and the first input end of the three-phase inverter circuit, the other end of the second capacitor is respectively connected to the second output end of the second voltage conversion circuit and the second input end of the three-phase inverter circuit, and the output end of the three-phase inverter circuit is connected to the motor.

7. The motor drive circuit according to any one of claims 1 to 4, characterized in that: The second voltage conversion circuit includes: a third capacitor, a fourth capacitor, a second controllable switch, a third controllable switch, a second diode, a third diode, a second inductor, a third inductor and a fifth capacitor, wherein: One end of the third capacitor is connected to one end of the pre-charging circuit, the other end of the third capacitor is connected to one end of the fourth capacitor, the other end of the fourth capacitor is connected to the second output end of the first voltage conversion circuit, and the first output end of the first voltage conversion circuit is also connected to the other end of the pre-charging circuit; A first end of the second controllable switch is connected to one end of the third capacitor, and a second end of the second controllable switch is connected to a cathode of the second diode and one end of the second inductor respectively; A first end of the third controllable switch is connected to the other end of the fourth capacitor, a second end of the third controllable switch is respectively connected to the anode of the third diode and one end of the third inductor, and a cathode of the third diode is respectively connected to the anode of the second diode, the other end of the third capacitor and one end of the fourth capacitor; The other end of the second inductor is connected to the first input end of the third voltage conversion circuit and one end of the fifth capacitor respectively, and the other end of the fifth capacitor is connected to the other end of the third inductor.

8. The motor drive circuit according to claim 7, characterized in that: The third voltage conversion circuit includes a three-phase inverter circuit.

9. The motor drive circuit according to claim 1, characterized in that: The voltage of the first alternating current is 575V, 460V or 380V.

10. A motor, characterized in that: Comprising the motor drive circuit according to any one of claims 1-9.

11. An electrical device, characterized in that: It comprises the motor drive circuit according to any one of claims 1 to 9, or the motor according to claim 9.

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