AC-DC conversion circuit of motor

Abstract

The present application provides an AC-DC conversion circuit for a motor, including a three-phase current source, an input mode switching circuit, a control circuit, a rectifier circuit, and an auxiliary power supply circuit, wherein the control circuit is used to control the adjustment of the input mode of the input mode switching circuit; the rectifier circuit is used to provide a target voltage range so that the auxiliary power supply circuit satisfies both a first circuit condition and a second circuit condition, wherein the first circuit condition refers to V_ctr being greater than a first preset voltage threshold, and the second circuit condition refers to V_ctr being less than a second preset voltage threshold, and the target voltage range corresponds to V_bus_min_ref and V_bus_max_ref of the bus voltage V_bus. The AC-DC conversion circuit for the motor of the present application can achieve a stable startup function in both a three-phase input mode and a single-phase input mode.

Description

Technical Field

[0001] The present application relates to the technical field related to an AC / DC converter of an electromechanical converter of a motor, and in particular to an AC / DC conversion circuit of a motor. Background Art

[0002] The control circuit in the AC / DC converter of the motor is powered by the auxiliary power supply circuit. Usually, the auxiliary power supply circuit is a flyback circuit, and its input voltage is the bus voltage V_bus of the AC / DC converter, that is, the bus voltage V_bus supplies power to the load and the auxiliary power supply circuit at the same time. For a fixed auxiliary power supply circuit, the allowable bus voltage V_bus range is fixed. When the motor is on standby, the bus voltage V_bus is determined by the uncontrolled rectifier voltage of the three-phase input of the AC / DC converter. Therefore, the activation requirement of the auxiliary power supply circuit can be met by setting the upper and lower limits of the three-phase input phase voltage.

[0003] For AC / DC converters with adjustable input modes, the current standby startup voltage design mechanism can no longer meet user needs. Summary of the invention

[0004] An embodiment of the present application provides an AC-DC conversion circuit of a motor, which can achieve a stable startup function for an auxiliary power supply circuit in both a three-phase input mode and a single-phase input mode standby state.

[0005] In a first aspect, an embodiment of the present application provides an AC-DC conversion circuit for a motor, including a three-phase current source, an input mode switching circuit, a control circuit, a rectifier circuit, and an auxiliary power supply circuit, wherein:

[0006] The three-phase current source is connected to the input mode switching circuit, the input mode switching circuit is connected to the rectifier circuit, the rectifier circuit is connected to the auxiliary power supply circuit, the auxiliary power supply circuit is connected to the control circuit and supplies power to the control circuit, and the control circuit is connected to the input mode switching circuit;

[0007] The control circuit is used to control the adjustment of the input mode of the input mode switching circuit, the input mode includes a three-phase input mode and a single-phase input mode, the three-phase input mode corresponds to the three-phase power supply mode of the three-phase current source, and the single-phase input mode corresponds to the single-phase power supply mode of the three-phase current source;

[0008] The rectifier circuit is used to provide a voltage within a target voltage range for the auxiliary power supply circuit so that the auxiliary power supply circuit satisfies a first circuit condition and a second circuit condition at the same time. The first circuit condition refers to that the output voltage V_ctr of the auxiliary power supply circuit is greater than a first preset voltage threshold, and the second circuit condition refers to that V_ctr is less than a second preset voltage threshold. The first preset voltage threshold is the minimum supply voltage for maintaining the normal operation of the control circuit, and the second preset voltage threshold is the maximum excitation voltage for maintaining the normal operation of the field effect transistor of the auxiliary power supply circuit. The target voltage range corresponds to a reference minimum value V_bus_min_ref and a reference maximum value V_bus_max_ref of the bus voltage V_bus of the rectifier circuit. V_bus_min_ref corresponds to the first circuit condition, and V_bus_max_ref corresponds to the second circuit condition.

[0009] In a possible implementation, the input mode switching circuit includes a first switch K1, a second switch K2, a third switch K3, a fourth switch K4, a fifth switch K5, and a sixth switch K6, wherein:

[0010] The first end K31 of the third switch K3 is connected to the A phase of the three-phase current source, and the second end K32 of the third switch K3 is connected to the A phase rectifier bridge arm of the rectifier circuit.

[0011] The first end K11 of the first switch K1 is connected to the B phase of the three-phase current source, the second end K12 of the first switch K1 is connected to the first end K61 of the sixth switch K6, the second end K62 of the sixth switch K6 is connected to the N line of the three-phase current source, the third end K13 of the first switch K1 is connected to the first end K41 of the fourth switch K4, the second end K42 of the fourth switch K4 is connected to the B phase rectifier bridge arm of the rectifier circuit,

[0012] The first end K21 of the second switch K2 is connected to the C phase of the three-phase current source, the second end K22 of the second switch K2 is connected to the first end K61 of the sixth switch K6, the third end K23 of the second switch K2 is connected to the first end K51 of the fifth switch K5, and the second end K52 of the fifth switch K5 is connected to the C phase rectifier bridge arm of the rectifier circuit.

[0013] In one possible implementation,

[0014] The switch action state of the input mode switching circuit corresponding to the three-phase power supply mode is: the first end K11 of the first switch K1 is turned on, the first end K21 of the second switch K2 is turned on, the third switch K3, the fourth switch K4, and the fifth switch K5 are turned on, and the sixth switch K6 is turned off;

[0015] The single-phase power supply mode includes AN single-phase power supply mode, BN single-phase power supply mode and CN single-phase power supply mode, wherein:

[0016] The switch action state of the input mode switching circuit corresponding to the AN single-phase power supply mode is: the third switch K3, the fourth switch K4, the second end K12 of the first switch K1, and the sixth switch K6 are turned on, the first end K21 of the second switch K2 is turned on, and the fifth switch K5 is turned off, or the third switch K3, the fifth switch K5, the second end K22 of the second switch K2, and the sixth switch K6 are turned on, the first end K11 of the first switch K1 is turned on, and the fourth switch K4 is turned off;

[0017] The switch action state of the input mode switching circuit corresponding to the BN single-phase power supply mode is: the first end K11 of the first switch K1, the fourth switch K4, the fifth switch K5, the second end K22 of the second switch K2, and the sixth switch K6 are turned on, and the third switch K3 is turned off;

[0018] The switch action state of the input mode switching circuit corresponding to the CN single-phase power supply mode is: the first end K21 of the second switch K2, the fifth switch K5, the fourth switch K4, the second end K12 of the first switch K1, and the sixth switch K6 are turned on, and the third switch K3 is turned off.

[0019] In a possible implementation manner, the bus voltage V_bus of the rectifier circuit is determined by the uncontrolled rectifier voltage input by the three-phase current source in the three-phase power supply mode or the single-phase power supply mode; wherein,

[0020] The maximum value V_in_max_3 and the minimum value V_in_min_3 of the input phase voltage of the three-phase current source in the three-phase power supply mode are respectively:

[0021] V_in_max_3 = V_bus_max_3 / (√2 × √3), where the √ in √2 and √3 represents the square root operator;

[0022] V_in_min_3=V_bus_min_3 / (√2×√3);

[0023] Wherein, V_bus_max_3 is the real maximum value of the bus voltage V_bus of the rectifier circuit in the three-phase power supply mode, and V_bus_min_3 is the real minimum value of the bus voltage V_bus of the rectifier circuit in the three-phase power supply mode;

[0024] The maximum value V_in_max_1 and the minimum value V_in_min_1 of the input phase voltage of the three-phase current source in the single-phase power supply mode are respectively:

[0025] V_in_max_1=V_bus_max_1 / √2;

[0026] V_in_min_1=V_bus_min_1 / √2;

[0027] Among them, V_bus_max_1 is the real maximum value of the bus voltage V_bus of the rectifier circuit in the single-phase power supply mode, and V_bus_min_1 is the real minimum value of the bus voltage V_bus of the rectifier circuit in the single-phase power supply mode.

[0028] In a possible implementation, if V_in_max_3=V_in_max_1, V_in_min_3=V_in_min_1,

[0029] Then V_bus_max_ref=V_in_max_3×√2×√3, V_bus_min_ref=V_in_min_1×√2.

[0030] In a possible implementation manner, the rectifier circuit is a Vienna rectifier circuit, and the Vienna rectifier circuit includes a first capacitor C1 and a second capacitor C2 connected in series.

[0031] In a possible implementation, the input mode switching circuit includes a first switch K1, a second switch K2, a third switch K3, a fourth switch K4, a fifth switch K5, a sixth switch K6 and a seventh switch K7, wherein:

[0032] The first end K31 of the third switch K3 is connected to the A phase of the three-phase current source, and the second end K32 of the third switch K3 is connected to the A phase rectifier bridge arm of the rectifier circuit.

[0033] The first end K11 of the first switch K1 is connected to the B phase of the three-phase current source, the second end K12 of the first switch K1 is connected to the first end K61 of the sixth switch K6, the second end K62 of the sixth switch K6 is connected to the N line of the three-phase current source, the third end K13 of the first switch K1 is connected to the first end K41 of the fourth switch K4, the second end K42 of the fourth switch K4 is connected to the B phase rectifier bridge arm of the rectifier circuit,

[0034] The first end K21 of the second switch K2 is connected to the C phase of the three-phase current source, the second end K22 of the second switch K2 is connected to the first end K61 of the sixth switch K6, the third end K23 of the second switch K2 is connected to the first end K51 of the fifth switch K5, and the second end K52 of the fifth switch K5 is connected to the C phase rectifier bridge arm of the rectifier circuit;

[0035] The first end of the seventh switch K7 is connected to the first end K61 of the sixth switch K6, and the second end K72 of the seventh switch K7 is connected to any circuit point between the middle lines of the first capacitor C1 and the second capacitor C2.

[0036] In one possible implementation,

[0037] The switch action state of the input mode switching circuit corresponding to the three-phase power supply mode is: the first end K11 of the first switch K1 is turned on, the first end K21 of the second switch K2 is turned on, the third switch K3, the fourth switch K4, and the fifth switch K5 are turned on, and the sixth switch K6 and the seventh switch K7 are turned off;

[0038] The single-phase power supply mode includes AN single-phase power supply mode, BN single-phase power supply mode and CN single-phase power supply mode, wherein:

[0039] The switch action state of the input mode switching circuit corresponding to the AN single-phase power supply mode is: the third switch K3, the fourth switch K4, the second end K12 of the first switch K1, the seventh switch K7, and the sixth switch K6 are turned on, the first end K21 of the second switch K2 is turned on, and the fifth switch K5 is turned off, or the third switch K3, the fifth switch K5, the second end K22 of the second switch K2, the seventh switch K7, and the sixth switch K6 are turned on, the first end K11 of the first switch K1 is turned on, and the fourth switch K4 is turned off;

[0040] The switch action state of the input mode switching circuit corresponding to the BN single-phase power supply mode is: the first end K11 of the first switch K1, the fourth switch K4, the fifth switch K5, the second end K22 of the second switch K2, the seventh switch K7, and the sixth switch K6 are turned on, and the third switch K3 is turned off;

[0041] The switch action state of the input mode switching circuit corresponding to the CN single-phase power supply mode is: the first end K21 of the second switch K2, the fifth switch K5, the fourth switch K4, the second end K12 of the first switch K1, the seventh switch K7, and the sixth switch K6 are turned on, and the third switch K3 is turned off.

[0042] In a possible implementation manner, the bus voltage V_bus of the rectifier circuit is determined by the uncontrolled rectifier voltage input by the three-phase current source in the three-phase power supply mode or the single-phase power supply mode; wherein,

[0043] The maximum value V_in_max_3 and the minimum value V_in_min_3 of the input phase voltage of the three-phase current source in the three-phase power supply mode are respectively:

[0044] V_in_max_3 = V_bus_max_3 / (√2 × √3), where the √ in √2 and √3 represents the square root operator;

[0045] V_in_min_3=V_bus_min_3 / (√2×√3);

[0046] Wherein, V_bus_max_3 is the real maximum value of the bus voltage V_bus of the rectifier circuit in the three-phase power supply mode, and V_bus_min_3 is the real minimum value of the bus voltage V_bus of the rectifier circuit in the three-phase power supply mode;

[0047] The maximum value V_in_max_1 and the minimum value V_in_min_1 of the input phase voltage of the three-phase current source in the single-phase power supply mode are respectively:

[0048] V_in_max_1=V_bus_max_1 / √2;

[0049] V_in_min_1=V_bus_min_1 / 2√2;

[0050] Among them, V_bus_max_1 is the real maximum value of the bus voltage V_bus of the rectifier circuit in the single-phase power supply mode, and V_bus_min_1 is the real minimum value of the bus voltage V_bus of the rectifier circuit in the single-phase power supply mode.

[0051] In a possible implementation, if V_in_max_3=V_in_max_1, V_in_min_3=V_in_min_1,

[0052] Then V_bus_max_ref=V_in_max_3×√2×√3, V_bus_min_ref=V_in_min_1×2√2.

[0053] It can be seen that in the embodiment of the present application, the AC-DC conversion circuit of the motor includes a three-phase current source, an input mode switching circuit, a control circuit, a rectifier circuit and an auxiliary power supply circuit. The control circuit is used to control the adjustment of the input mode of the input mode switching circuit. The input mode includes a three-phase input mode and a single-phase input mode. The three-phase input mode corresponds to the three-phase power supply mode of the three-phase current source, and the single-phase input mode corresponds to the single-phase power supply mode of the three-phase current source. Since the rectifier circuit provides the auxiliary power supply circuit with a voltage within the target voltage range so that the auxiliary power supply circuit satisfies the first circuit condition and the second circuit condition at the same time, the first circuit condition refers to the auxiliary The output voltage V_ctr of the power supply circuit is greater than the first preset voltage threshold, and the second circuit condition means that V_ctr is less than the second preset voltage threshold. The first preset voltage threshold is the minimum supply voltage to maintain the normal operation of the control circuit, and the second preset voltage threshold is the maximum excitation voltage to maintain the normal operation of the field effect tube of the auxiliary power supply circuit. The target voltage range corresponds to the reference minimum value V_bus_min_ref and the reference maximum value V_bus_max_ref of the bus voltage V_bus of the rectifier circuit. V_bus_min_ref corresponds to the first circuit condition, and V_bus_max_ref corresponds to the second circuit condition. It can be seen that the AC-DC conversion circuit of the motor can meet the first and second circuit conditions in both the three-phase input mode and the single-phase input mode, thereby achieving stable startup of the auxiliary power supply circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a circuit diagram of an AC-DC conversion circuit 10 of a motor provided in the present application;

[0055] Figure 2 is a circuit diagram of an input mode switching circuit 110 provided by the present application;

[0056] Figure 3 This is a circuit diagram of an AC-DC conversion circuit of a motor provided by the present application, in which the rectifier circuit 130 is a Vienna rectifier circuit;

[0057] Figure 4 It is a circuit diagram of another input mode switching circuit 110 of a motor provided in the present application. DETAILED DESCRIPTION

[0058] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described below in conjunction with the accompanying drawings.

[0059] The "embodiment" mentioned in this article means that the specific features, structures or characteristics described in conjunction with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It can be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0060] In the present application, "at least one (item)" means one or more, "more than one" means two or more, "at least two (items)" means two or three and more than three, and "and / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. "Or" means that two relationships may exist, such as only A exists, only B exists; when A and B are not mutually exclusive, it can also mean that there are three relationships, such as only A exists, only B exists, and A and B exist at the same time. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c".

[0061] It should be noted that the connections between the circuit units and circuit devices described in this application are all electrical connection relationships, and the specific implementation methods of the electrical connection relationships can be various, such as connection between contacts, wire connection, socket connection, etc., which are not limited here.

[0062] like Figure 1 As shown, the embodiment of the present application provides an AC-DC conversion circuit 10 for a motor, including a three-phase current source 100, an input mode switching circuit 110, a control circuit 120, a rectifier circuit 130, an auxiliary power supply circuit 140, and a load circuit 150, wherein:

[0063] The three-phase current source 100 is connected to the input mode switching circuit 110, the input mode switching circuit 110 is connected to the rectifier circuit 130, the rectifier circuit 130 is connected to the auxiliary power supply circuit 140, the auxiliary power supply circuit 140 is connected to the control circuit 120 and supplies power to the control circuit 120, and the control circuit 120 is connected to the input mode switching circuit 110;

[0064] The rectifier circuit 130 is connected to the load circuit 150 to supply power to the load circuit 150. The auxiliary power supply circuit 140 is a flyback circuit, wherein the bus voltage V_bus of the rectifier circuit 130 supplies power to the load and the auxiliary power supply circuit at the same time.

[0065] The control circuit 120 is used to control the adjustment of the input mode of the input mode switching circuit 110, the input mode includes a three-phase input mode and a single-phase input mode, the three-phase input mode corresponds to the three-phase power supply mode of the three-phase current source, and the single-phase input mode corresponds to the single-phase power supply mode of the three-phase current source;

[0066] The rectifier circuit 130 is used to provide a voltage within a target voltage range for the auxiliary power supply circuit 140 so that the auxiliary power supply circuit 140 satisfies a first circuit condition and a second circuit condition at the same time. The first circuit condition refers to that the output voltage V_ctr of the auxiliary power supply circuit 140 is greater than a first preset voltage threshold, and the second circuit condition refers to that V_ctr is less than a second preset voltage threshold. The first preset voltage threshold is the minimum supply voltage for maintaining the normal operation of the control circuit 120, and the second preset voltage threshold is the maximum excitation voltage for maintaining the normal operation of the field effect transistor of the auxiliary power supply circuit 140. The target voltage range corresponds to a reference minimum value V_bus_min_ref and a reference maximum value V_bus_max_ref of the bus voltage V_bus of the rectifier circuit 130. V_bus_min_ref corresponds to the first circuit condition, and V_bus_max_ref corresponds to the second circuit condition.

[0067] It can be seen that in the embodiment of the present application, the AC-DC conversion circuit 10 of the motor includes a three-phase current source 100, an input mode switching circuit 110, a control circuit 120, a rectifier circuit 130 and an auxiliary power supply circuit 140. The control circuit 120 is used to control the adjustment of the input mode of the input mode switching circuit 110. The input mode includes a three-phase input mode and a single-phase input mode. The three-phase input mode corresponds to the three-phase power supply mode of the three-phase current source 100, and the single-phase input mode corresponds to the single-phase power supply mode of the three-phase current source. Since the rectifier circuit 130 provides the auxiliary power supply circuit 140 with a voltage within the target voltage range so that the auxiliary power supply circuit satisfies the first circuit condition and the second circuit condition at the same time, The first circuit condition means that the output voltage V_ctr of the auxiliary power supply circuit 140 is greater than the first preset voltage threshold, and the second circuit condition means that V_ctr is less than the second preset voltage threshold. The first preset voltage threshold is the minimum supply voltage for maintaining the normal operation of the control circuit 120, and the second preset voltage threshold is the maximum excitation voltage for maintaining the normal operation of the field effect tube of the auxiliary power supply circuit 140. The target voltage range corresponds to the reference minimum value V_bus_min_ref and the reference maximum value V_bus_max_ref of the bus voltage V_bus of the rectifier circuit 130. V_bus_min_ref corresponds to the first circuit condition, and V_bus_max_ref corresponds to the second circuit condition. It can be seen that the AC-DC conversion circuit 10 of the motor can meet the first and second circuit conditions in both the three-phase input mode and the single-phase input mode, thereby achieving stable startup of the auxiliary power supply circuit 140.

[0068] In one possible example, Figure 2 , a circuit diagram of an input mode switching circuit 110 is shown, the input mode switching circuit 110 includes a first switch K1, a second switch K2, a third switch K3, a fourth switch K4, a fifth switch K5, and a sixth switch K6, wherein:

[0069] The first end K31 of the third switch K3 is connected to the A phase of the three-phase current source 100, and the second end K32 of the third switch K3 is connected to the A phase rectifier bridge arm of the rectifier circuit 130.

[0070] The first end K11 of the first switch K1 is connected to the B phase of the three-phase current source 100, the second end K12 of the first switch K1 is connected to the first end K61 of the sixth switch K6, the second end K62 of the sixth switch K6 is connected to the N line of the three-phase current source, the third end K13 of the first switch K1 is connected to the first end K41 of the fourth switch K4, the second end K42 of the fourth switch K4 is connected to the B phase rectifier bridge arm of the rectifier circuit 130,

[0071] The first end K21 of the second switch K2 is connected to the C phase of the three-phase current source 100, the second end K22 of the second switch K2 is connected to the first end K61 of the sixth switch K6, the third end K23 of the second switch K2 is connected to the first end K51 of the fifth switch K5, and the second end K52 of the fifth switch K5 is connected to the C phase rectifier bridge arm of the rectifier circuit 130.

[0072] The third switch K3, the fourth switch K4, the fifth switch K5 and the sixth switch K6 are unidirectional switches such as unidirectional relays, which are used to connect the circuit branches of the single-phase and the corresponding rectifier bridge arm, and the disconnected state can be used to avoid surge voltage when the single-phase power supply state is switched;

[0073] The first switch K1 or the second switch K2 is a bidirectional switch such as a parallel relay, which is used to select the connection relationship between the rectifier bridge arm corresponding to a single phase and the single phase or N line, thereby cooperating to realize the switching between the three-phase input mode and the single-phase input mode.

[0074] It can be seen that in this example, for the connection mode of the input mode switching circuit 110 and the rectifier circuit 130 in non-bypass mode, the adjustable control of the three-phase input mode and the single-phase input mode is achieved through the cooperation of the first switch K1 to the sixth switch K6, thereby improving the flexibility of the power supply of the AC-DC conversion circuit 10 of the motor.

[0075] In a possible example, the switch action state of the input mode switching circuit 110 corresponding to the three-phase power supply mode is: the first end K11 of the first switch K1 is turned on, the first end K21 of the second switch K2 is turned on, the third switch K3, the fourth switch K4, and the fifth switch K5 are turned on, and the sixth switch K6 is turned off;

[0076] The single-phase power supply mode includes AN single-phase power supply mode, BN single-phase power supply mode and CN single-phase power supply mode, wherein:

[0077] The switch action state of the input mode switching circuit 110 corresponding to the AN single-phase power supply mode is: the third switch K3, the fourth switch K4, the second end K12 of the first switch K1, and the sixth switch K6 are turned on, the first end K21 of the second switch K2 is turned on, and the fifth switch K5 is turned off, or the third switch K3, the fifth switch K5, the second end K22 of the second switch K2, and the sixth switch K6 are turned on, the first end K11 of the first switch K1 is turned on, and the fourth switch K4 is turned off;

[0078] The switch action state of the input mode switching circuit 110 corresponding to the BN single-phase power supply mode is: the first end K11 of the first switch K1, the fourth switch K4, the fifth switch K5, the second end K22 of the second switch K2, and the sixth switch K6 are turned on, and the third switch K3 is turned off;

[0079] The switch action state of the input mode switching circuit 110 corresponding to the CN single-phase power supply mode is: the first end K21 of the second switch K2, the fifth switch K5, the fourth switch K4, the second end K12 of the first switch K1, and the sixth switch K6 are turned on, and the third switch K3 is turned off.

[0080] It can be seen that in this example, the input mode switching circuit 110 can flexibly and accurately realize the control of the three-phase input mode and the single-phase input mode by adjusting the action states of the first switch K1 to the sixth switch K6, thereby improving the stability and flexibility of the three-phase power supply mode and the single-phase power supply mode control of the motor's AC-DC conversion circuit 10.

[0081] In a possible example, the bus voltage V_bus of the rectifier circuit 130 is determined by the uncontrolled rectifier voltage input by the three-phase current source 100 in the three-phase power supply mode or the single-phase power supply mode; wherein,

[0082] The maximum value V_in_max_3 and the minimum value V_in_min_3 of the input phase voltage of the three-phase current source 100 in the three-phase power supply mode are respectively:

[0083] V_in_max_3 = V_bus_max_3 / (√2 × √3), where the √ in √2 and √3 represents the square root operator;

[0084] V_in_min_3=V_bus_min_3 / (√2×√3);

[0085] Wherein, V_bus_max_3 is the real maximum value of the bus voltage V_bus of the rectifier circuit 130 in the three-phase power supply mode, and V_bus_min_3 is the real minimum value of the bus voltage V_bus of the rectifier circuit 130 in the three-phase power supply mode;

[0086] The maximum value V_in_max_1 and the minimum value V_in_min_1 of the input phase voltage of the three-phase current source 100 in the single-phase power supply mode are respectively:

[0087] V_in_max_1=V_bus_max_1 / √2;

[0088] V_in_min_1=V_bus_min_1 / √2;

[0089] Among them, V_bus_max_1 is the actual maximum value of the bus voltage V_bus of the rectifier circuit 130 in the single-phase power supply mode, and V_bus_min_1 is the actual minimum value of the bus voltage V_bus of the rectifier circuit 130 in the single-phase power supply mode.

[0090] It can be seen that in this example, by analyzing the true maximum value and true minimum value of the bus voltage V_bus in the AC-DC conversion circuit 10 of the motor in the three-phase power supply mode and the single-phase power supply mode, the correlation between the critical values ​​of the first circuit condition and the second circuit condition required for the stable starting control circuit 120 and each true maximum value and each true minimum value can be accurately determined, and the controlled boundary value range of the bus voltage V_bus can be determined based on the correlation, thereby improving the feasibility of the starting control circuit 120.

[0091] In one possible example, if V_in_max_3=V_in_max_1, V_in_min_3=V_in_min_1,

[0092] Then V_bus_max_ref=V_in_max_3×√2×√3, V_bus_min_ref=V_in_min_1×√2.

[0093] It can be seen that in this example, when the input mode switching circuit 110 is in the non-bypass connection mode, the critical value of the first circuit condition is V_in_min_1×√2 in the single-phase power supply mode, and the critical value of the second circuit condition is V_in_max_3×√2×√3 in the three-phase power supply mode. Correspondingly, it is only necessary to determine V_in_max_3 in the three-phase power supply mode according to the aforementioned critical value relationship and the preset V_bus_max_ref, and to determine V_bus_min_ref in the single-phase mode according to the aforementioned critical value relationship and V_bus_min_ref, so as to achieve stable starting of the AC-DC conversion circuit 10 of the motor in different modes.

[0094] In one possible example, Figure 3 The circuit diagram of the AC-DC conversion circuit 10 of the motor in which the rectifier circuit 130 is a Vienna rectifier circuit is shown. The rectifier circuit 130 is a Vienna rectifier circuit, and the Vienna rectifier circuit includes a first capacitor C1 and a second capacitor C2 connected in series.

[0095] Among them, the Vienna rectifier circuit also includes a first inductor L1, a second inductor L2, and a third inductor L3, and the three-phase bridge arm includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, and a sixth diode D6 that play a clamping role, and a first bidirectional switch tube Q1, a second bidirectional switch tube Q2, a third bidirectional switch tube Q3, a fourth bidirectional switch tube Q4, a fifth bidirectional switch tube Q5, and a sixth bidirectional switch tube Q6 for controlling the charging and discharging of the inductor.

[0096] Among them, the first end of the first inductor L1 is connected to the second end K32 of the third switch K3, the second end of the first inductor L1 is connected to the anode of the first diode D1, the cathode of the second diode D2 and the first end of the first bidirectional switch tube Q1, the first end of the second inductor L2 is connected to the second end K42 of the fourth switch K4, the second end of the second inductor L2 is connected to the anode of the third diode D3, the cathode of the fourth diode D4 and the first end of the third bidirectional switch tube Q3, the first end of the third inductor L3 is connected to the second end of the fifth switch K5, the second end of the third inductor L3 is connected to the anode of the fifth diode D5, the cathode of the sixth diode D6 and the first end of the fifth bidirectional switch tube Q5, the cathode of the first diode D1, the cathode of the third diode D3 and the cathode of the fifth diode D5 are connected to the first end of the first capacitor C1, and the cathode of the first capacitor C1 is connected to the cathode of the fifth diode D5. The two ends are connected to the second end of the second bidirectional switch tube Q2, the second end of the fourth bidirectional switch tube Q4, the second end of the sixth bidirectional switch tube Q6 and the first end of the second capacitor C2, the second end of the second capacitor C2 is connected to the anode of the second diode D2, the anode of the fourth diode D4 and the anode of the sixth diode D6, the second end of the first bidirectional switch tube Q1 is connected to the first end of the second bidirectional switch tube Q2, the second end of the third bidirectional switch tube Q3 is connected to the first end of the fourth bidirectional switch tube Q4, the second end of the fifth bidirectional switch tube Q5 is connected to the first end of the sixth bidirectional switch tube Q6, and the first bidirectional switch tube Q1, the second bidirectional switch tube Q2, the third bidirectional switch tube Q3, the fourth bidirectional switch tube Q4, the fifth bidirectional switch tube Q5 and the sixth bidirectional switch tube Q6 all include parallel diodes and triodes, and the diodes and triodes are arranged in opposite directions.

[0097] Among them, the first inductor L1, the first bidirectional switch tube Q1, and the second bidirectional switch tube Q2 constitute the bridge arm corresponding to A in the rectifier bridge, the second inductor L2, the third bidirectional switch tube Q3, and the fourth bidirectional switch tube Q4 constitute the bridge arm corresponding to B in the rectifier bridge, and the third inductor L3, the fifth bidirectional switch tube Q5, and the sixth bidirectional switch tube Q6 constitute the rectifier bridge corresponding to C in the rectifier bridge. The purpose of the rectifier bridge is to make the phase of the input current and the input voltage of the rectifier circuit 130 consistent. Specifically, the control circuit 120 samples the input voltage of the three-phase AC power supply in real time, and performs closed-loop control according to the state relationship between the input voltage and the output voltage.

[0098] The first end of the first inductor L1 is connected to the second end K32 of the third switch K3, the second end of the first inductor L1 is connected to the anode of the first diode D1, the cathode of the second diode D2 and the first end of the first bidirectional switch tube Q1 (the first end of the first bidirectional switch tube Q1 corresponds to the cathode of the diode of the first bidirectional switch tube Q1 and the drain of the MOS tube of the first bidirectional switch tube Q1 in the figure), and the second end of the first bidirectional switch tube Q1 (corresponding to the anode of the diode of the first bidirectional switch tube Q1 and the source of the MOS tube of the first bidirectional switch tube Q1 in the figure) is connected to the first end of the second bidirectional switch tube Q2 (corresponding to the anode of the diode of the second bidirectional switch tube Q2 and the source of the MOS tube of the second bidirectional switch tube Q2 in the figure) The first end of the second inductor L2 is connected to the second end K42 of the fourth switch K4, the second end of the second inductor L2 is connected to the anode of the third diode D3, the cathode of the fourth diode D4 and the first end of the third bidirectional switch Q3 (the first end of the third bidirectional switch Q3 corresponds to the cathode of the diode of the third bidirectional switch Q3 and the drain of the MOS of the third bidirectional switch Q3 in the figure), and the second end of the third bidirectional switch Q3 (corresponding to the anode of the diode of the third bidirectional switch Q3 and the drain of the MOS of the third bidirectional switch Q3 in the figure) is connected to the first end of the fourth bidirectional switch Q4 (corresponding to the cathode of the diode of the third bidirectional switch Q3 and the drain of the MOS of the third bidirectional switch Q4 in the figure) The first end of the third inductor L3 is connected to the second end K52 of the fifth switch K5, the second end of the third inductor L3 is connected to the anode of the fifth diode D5, the cathode of the sixth diode D6 and the first end of the fifth bidirectional switch Q5 (the first end of the fifth bidirectional switch Q5 corresponds to the cathode of the diode of the fifth bidirectional switch Q5 and the drain of the MOS of the fifth bidirectional switch Q5 in the figure), and the second end of the fifth bidirectional switch Q5 (corresponding to the anode of the diode of the fifth bidirectional switch Q5 and the drain of the MOS of the fifth bidirectional switch Q5 in the figure) is connected to the first end of the sixth bidirectional switch Q6 (corresponding to the cathode of the diode of the fifth bidirectional switch Q5 and the drain of the MOS of the fifth bidirectional switch Q5 in the figure) The cathode of the first diode D1, the cathode of the third diode D3 and the cathode of the fifth diode D5 are connected to the first end of the first capacitor C1, the second end of the first capacitor C1 is connected to the second end of the second bidirectional switch tube Q2 (corresponding to the cathode of the diode of the second bidirectional switch tube Q2 and the drain of the MOS tube of the second bidirectional switch tube Q2 in the figure), the second end of the fourth bidirectional switch tube Q4 (corresponding to the cathode of the diode of the fourth bidirectional switch tube Q4 and the drain of the MOS tube of the fourth bidirectional switch tube Q4 in the figure), the second end of the sixth bidirectional switch tube Q6 (corresponding to the cathode of the diode of the sixth bidirectional switch tube Q6 and the drain of the MOS tube of the sixth bidirectional switch tube Q6 in the figure) and the first end of the second capacitor C2, and the second end of the second capacitor C2 is connected to the anode of the second diode D2, the anode of the fourth diode D4 and the anode of the sixth diode D6.

[0099] Since the Vienna circuit is a commonly used circuit, the circuit structure and control mode of the circuit are only examples here and are not limited to the only ones.

[0100] It can be seen that in this example, the rectifier circuit 130 can be a Vienna rectifier circuit, so that stable power control can be achieved in the three-phase power supply mode and the single-phase power supply mode.

[0101] In one possible example, Figure 4 FIG. 1 is a circuit diagram of another input mode switching circuit 110 of a motor AC-DC conversion circuit 10, wherein the input mode switching circuit 110 includes a first switch K1, a second switch K2, a third switch K3, a fourth switch K4, a fifth switch K5, a sixth switch K6 and a seventh switch K7, wherein:

[0102] The first end K31 of the third switch K3 is connected to the A phase of the three-phase current source 100, and the second end K32 of the third switch K3 is connected to the A phase rectifier bridge arm of the rectifier circuit 130.

[0103] The first end K11 of the first switch K1 is connected to the B phase of the three-phase current source 100, the second end K12 of the first switch K1 is connected to the first end K61 of the sixth switch K6, the second end K62 of the sixth switch K6 is connected to the N line of the three-phase current source, the third end K13 of the first switch K1 is connected to the first end K41 of the fourth switch K4, the second end K42 of the fourth switch K4 is connected to the B phase rectifier bridge arm of the rectifier circuit 130,

[0104] The first end K21 of the second switch K2 is connected to the C phase of the three-phase current source 100, the second end K22 of the second switch K2 is connected to the first end K61 of the sixth switch K6, the third end K23 of the second switch K2 is connected to the first end K51 of the fifth switch K5, and the second end K52 of the fifth switch K5 is connected to the C phase rectifier bridge arm of the rectifier circuit 130;

[0105] The first end of the seventh switch K7 is connected to the first end K61 of the sixth switch K6, and the second end K72 of the seventh switch K7 is connected to any circuit point between the middle lines of the first capacitor C1 and the second capacitor C2.

[0106] In a possible example, the switch action state of the input mode switching circuit 110 corresponding to the three-phase power supply mode is: the first end K11 of the first switch K1 is turned on, the first end K21 of the second switch K2 is turned on, the third switch K3, the fourth switch K4, and the fifth switch K5 are turned on, and the sixth switch K6 and the seventh switch K7 are turned off;

[0107] The single-phase power supply mode includes AN single-phase power supply mode, BN single-phase power supply mode and CN single-phase power supply mode, wherein:

[0108] The switch action state of the input mode switching circuit 110 corresponding to the AN single-phase power supply mode is: the third switch K3, the fourth switch K4, the second end K12 of the first switch K1, the seventh switch K7, and the sixth switch K6 are turned on, the first end K21 of the second switch K2 is turned on, and the fifth switch K5 is turned off, or the third switch K3, the fifth switch K5, the second end K22 of the second switch K2, the seventh switch K7, and the sixth switch K6 are turned on, the first end K11 of the first switch K1 is turned on, and the fourth switch K4 is turned off;

[0109] The switch action state of the input mode switching circuit 110 corresponding to the BN single-phase power supply mode is: the first end K11 of the first switch K1, the fourth switch K4, the fifth switch K5, the second end K22 of the second switch K2, the seventh switch K7, and the sixth switch K6 are turned on, and the third switch K3 is turned off;

[0110] The switch action state of the input mode switching circuit 110 corresponding to the CN single-phase power supply mode is: the first end K21 of the second switch K2, the fifth switch K5, the fourth switch K4, the second end K12 of the first switch K1, the seventh switch K7, and the sixth switch K6 are turned on, and the third switch K3 is turned off.

[0111] It can be seen that, in this example, the seventh switch K7 in the input mode switching circuit 110 realizes the bypass connection mode with the rectifier circuit 130 .

[0112] In a possible example, the bus voltage V_bus of the rectifier circuit 130 is determined by the uncontrolled rectifier voltage input by the three-phase current source 100 in the three-phase power supply mode or the single-phase power supply mode; wherein,

[0113] The maximum value V_in_max_3 and the minimum value V_in_min_3 of the input phase voltage of the three-phase current source 100 in the three-phase power supply mode are respectively:

[0114] V_in_max_3 = V_bus_max_3 / (√2 × √3), where the √ in √2 and √3 represents the square root operator;

[0115] V_in_min_3=V_bus_min_3 / (√2×√3);

[0116] Wherein, V_bus_max_3 is the real maximum value of the bus voltage V_bus of the rectifier circuit 130 in the three-phase power supply mode, and V_bus_min_3 is the real minimum value of the bus voltage V_bus of the rectifier circuit 130 in the three-phase power supply mode;

[0117] The maximum value V_in_max_1 and the minimum value V_in_min_1 of the input phase voltage of the three-phase current source 100 in the single-phase power supply mode are respectively:

[0118] V_in_max_1=V_bus_max_1 / √2;

[0119] V_in_min_1=V_bus_min_1 / 2√2;

[0120] Among them, V_bus_max_1 is the actual maximum value of the bus voltage V_bus of the rectifier circuit 130 in the single-phase power supply mode, and V_bus_min_1 is the actual minimum value of the bus voltage V_bus of the rectifier circuit 130 in the single-phase power supply mode.

[0121] Among them, see Figure 4 , taking the AN phase single-phase power supply mode, and the switch state conditions are: the third switch K3, the fifth switch K5, the second end K22 of the second switch K2, the seventh switch K7, the sixth switch K6 are turned on, the first end K11 of the first switch K1 is turned on, and the fourth switch K4 is turned off as an example, the uncontrolled rectifier voltage in this mode is respectively charged by the positive and negative half bus bars, and the specific circuit process principle analysis is as follows:

[0122] In standby mode, the control mode of the bidirectional switch tubes of the rectifier bridge arms of the three phases A, B, and C, namely, the first bidirectional switch tube Q1, the second bidirectional switch tube Q2, the third bidirectional switch tube Q3, the fourth bidirectional switch tube Q4, the fifth bidirectional switch tube Q5, and the sixth bidirectional switch tube Q6, are all turned off; and,

[0123] In the positive half cycle of the AN current source power supply, the A phase has a high potential, the N line has a low potential, the first diode D1 is turned on, the upper electrode of the first capacitor C1 (the electrode connected to the cathode of the first diode D1) maintains a high potential with the A phase via the first diode D1, the first inductor L1, and the third switch K3, the lower electrode of the first capacitor C1 (the electrode connected to the second end K72 of the seventh switch K7) maintains a low potential with the N line via the seventh switch K7 and the sixth switch K6, and the upper electrode of the second capacitor C2 (the electrode connected to the first capacitor C2) maintains a low potential with the N line. 1) is kept at a low potential with the N line via the seventh switch K7 and the sixth switch K6, and the lower electrode of the second capacitor C2 (referring to the electrode connected to the anode of the second diode D2) is kept at a low potential with the N line via the sixth diode D6, the third inductor L3, the fifth switch K5, the second switch K2, and the sixth switch K6. It can be seen that the first capacitor C1 is charged, and the second capacitor C2 is not charged. The voltage on the first capacitor C1 that is charged alone is equal to the peak value of V_AN, that is, √2×V_AN (the effective value of the AN phase current source); and,

[0124] In the negative half cycle of the AN current source power supply, the A phase is at a low potential, the N line is at a high potential, the second diode D2 is turned on, the upper electrode of the second capacitor C2, the lower electrode of the charged first capacitor C1, the seventh switch K7, the sixth switch K6 and the N line maintain a high potential, the lower electrode of the second capacitor C2 maintains a low potential with the A phase through the second diode D2, the first inductor L1, the third switch K3, the second capacitor C2 is charged, and the voltage on the second capacitor C2 that is charged alone is equal to the peak value of V_AN, that is, √2×V_AN (effective value);

[0125] It can be known that the first capacitor C1 and the second capacitor C2 have been charged separately, and there is a time point in a single cycle that makes the superimposed voltage of the first capacitor C1 / the second capacitor C2 2×√2×V_AN.

[0126] Therefore, the single-phase input voltage required to reach the lower limit V_bus_min_1 of the bus voltage V_bus is: V_bus_min_1=2×√2×V_AN.

[0127] In one possible example, if V_in_max_3=V_in_max_1, V_in_min_3=V_in_min_1,

[0128] Then V_bus_max_ref=V_in_max_3×√2×√3, V_bus_min_ref=V_in_min_1×2√2.

[0129] It can be seen that in this example, in the bypass connection mode of the input mode switching circuit 110 and the rectifier circuit 130, due to the voltage boost effect of V_bus_min_1 relative to the non-bypass mode, in the bypass connection mode circuit system of this embodiment, the input side voltage in the single-phase power supply mode only needs half of the input side voltage in the non-bypass mode to achieve the same starting function, thereby increasing the use range of the effective working voltage allowed by the AC-DC conversion circuit 10 of the motor and improving the scenario applicability of the circuit system.

Claims

1. An AC-DC conversion circuit for a motor, characterized in that: It includes a three-phase current source, an input mode switching circuit, a control circuit, a rectifier circuit and an auxiliary power supply circuit, wherein: The three-phase current source is connected to the input mode switching circuit, the input mode switching circuit is connected to the rectifier circuit, the rectifier circuit is connected to the auxiliary power supply circuit, the auxiliary power supply circuit is connected to the control circuit and supplies power to the control circuit, and the control circuit is connected to the input mode switching circuit; The control circuit is used to control the adjustment of the input mode of the input mode switching circuit, the input mode includes a three-phase input mode and a single-phase input mode, the three-phase input mode corresponds to the three-phase power supply mode of the three-phase current source, and the single-phase input mode corresponds to the single-phase power supply mode of the three-phase current source; The rectifier circuit is used to provide a voltage within a target voltage range for the auxiliary power supply circuit so that the auxiliary power supply circuit satisfies a first circuit condition and a second circuit condition at the same time. The first circuit condition refers to that the output voltage V_ctr of the auxiliary power supply circuit is greater than a first preset voltage threshold, and the second circuit condition refers to that V_ctr is less than a second preset voltage threshold. The first preset voltage threshold is the minimum supply voltage for maintaining the normal operation of the control circuit, and the second preset voltage threshold is the maximum excitation voltage for maintaining the normal operation of the field effect transistor of the auxiliary power supply circuit. The target voltage range corresponds to a reference minimum value V_bus_min_ref and a reference maximum value V_bus_max_ref of the bus voltage V_bus of the rectifier circuit. V_bus_min_ref corresponds to the first circuit condition, and V_bus_max_ref corresponds to the second circuit condition.

2. The AC-DC conversion circuit of the motor according to claim 1, characterized in that: The input mode switching circuit includes a first switch K1, a second switch K2, a third switch K3, a fourth switch K4, a fifth switch K5, and a sixth switch K6, wherein: The first end K31 of the third switch K3 is connected to the A phase of the three-phase current source, and the second end K32 of the third switch K3 is connected to the A phase rectifier bridge arm of the rectifier circuit. The first end K11 of the first switch K1 is connected to the B phase of the three-phase current source, the second end K12 of the first switch K1 is connected to the first end K61 of the sixth switch K6, the second end K62 of the sixth switch K6 is connected to the N line of the three-phase current source, the third end K13 of the first switch K1 is connected to the first end K41 of the fourth switch K4, the second end K42 of the fourth switch K4 is connected to the B phase rectifier bridge arm of the rectifier circuit, The first end K21 of the second switch K2 is connected to the C phase of the three-phase current source, the second end K22 of the second switch K2 is connected to the first end K61 of the sixth switch K6, the third end K23 of the second switch K2 is connected to the first end K51 of the fifth switch K5, and the second end K52 of the fifth switch K5 is connected to the C phase rectifier bridge arm of the rectifier circuit.

3. The AC-DC conversion circuit of the motor according to claim 2, characterized in that: The switch action state of the input mode switching circuit corresponding to the three-phase power supply mode is: the first end K11 of the first switch K1 is turned on, the first end K21 of the second switch K2 is turned on, the third switch K3, the fourth switch K4, and the fifth switch K5 are turned on, and the sixth switch K6 is turned off; The single-phase power supply mode includes AN single-phase power supply mode, BN single-phase power supply mode and CN single-phase power supply mode, wherein: The switch action state of the input mode switching circuit corresponding to the AN single-phase power supply mode is: the third switch K3, the fourth switch K4, the second end K12 of the first switch K1, and the sixth switch K6 are turned on, the first end K21 of the second switch K2 is turned on, and the fifth switch K5 is turned off, or the third switch K3, the fifth switch K5, the second end K22 of the second switch K2, and the sixth switch K6 are turned on, the first end K11 of the first switch K1 is turned on, and the fourth switch K4 is turned off; The switch action state of the input mode switching circuit corresponding to the BN single-phase power supply mode is: the first end K11 of the first switch K1, the fourth switch K4, the fifth switch K5, the second end K22 of the second switch K2, and the sixth switch K6 are turned on, and the third switch K3 is turned off; The switch action state of the input mode switching circuit corresponding to the CN single-phase power supply mode is: the first end K21 of the second switch K2, the fifth switch K5, the fourth switch K4, the second end K12 of the first switch K1, and the sixth switch K6 are turned on, and the third switch K3 is turned off.

4. The AC-DC conversion circuit of the motor according to claim 3, characterized in that: The bus voltage V_bus of the rectifier circuit is determined by the uncontrolled rectifier voltage input by the three-phase current source in the three-phase power supply mode or the single-phase power supply mode; wherein, The maximum value V_in_max_3 and the minimum value V_in_min_3 of the input phase voltage of the three-phase current source in the three-phase power supply mode are respectively: V_in_max_3 = V_bus_max_3 / (√2 × √3), where the √ in √2 and √3 represents the square root operator; V_in_min_3=V_bus_min_3 / (√2×√3); Wherein, V_bus_max_3 is the real maximum value of the bus voltage V_bus of the rectifier circuit in the three-phase power supply mode, and V_bus_min_3 is the real minimum value of the bus voltage V_bus of the rectifier circuit in the three-phase power supply mode; The maximum value V_in_max_1 and the minimum value V_in_min_1 of the input phase voltage of the three-phase current source in the single-phase power supply mode are respectively: V_in_max_1=V_bus_max_1 / √2; V_in_min_1=V_bus_min_1 / √2; Among them, V_bus_max_1 is the real maximum value of the bus voltage V_bus of the rectifier circuit in the single-phase power supply mode, and V_bus_min_1 is the real minimum value of the bus voltage V_bus of the rectifier circuit in the single-phase power supply mode.

5. The AC-DC conversion circuit of the motor according to claim 4, characterized in that: If V_in_max_3=V_in_max_1, V_in_min_3=V_in_min_1, Then V_bus_max_ref=V_in_max_3×√2×√3, V_bus_min_ref=V_in_min_1×√2.

6. The AC-DC conversion circuit of a motor according to claim 1, characterized in that: The rectifier circuit is a Vienna rectifier circuit, and the Vienna rectifier circuit includes a first capacitor C1 and a second capacitor C2 connected in series.

7. The AC-DC conversion circuit of the motor according to claim 6, characterized in that: The input mode switching circuit includes a first switch K1, a second switch K2, a third switch K3, a fourth switch K4, a fifth switch K5, a sixth switch K6 and a seventh switch K7, wherein: The first end K31 of the third switch K3 is connected to the A phase of the three-phase current source, and the second end K32 of the third switch K3 is connected to the A phase rectifier bridge arm of the rectifier circuit. The first end K11 of the first switch K1 is connected to the B phase of the three-phase current source, the second end K12 of the first switch K1 is connected to the first end K61 of the sixth switch K6, the second end K62 of the sixth switch K6 is connected to the N line of the three-phase current source, the third end K13 of the first switch K1 is connected to the first end K41 of the fourth switch K4, the second end K42 of the fourth switch K4 is connected to the B phase rectifier bridge arm of the rectifier circuit, The first end K21 of the second switch K2 is connected to the C phase of the three-phase current source, the second end K22 of the second switch K2 is connected to the first end K61 of the sixth switch K6, the third end K23 of the second switch K2 is connected to the first end K51 of the fifth switch K5, and the second end K52 of the fifth switch K5 is connected to the C phase rectifier bridge arm of the rectifier circuit; The first end of the seventh switch K7 is connected to the first end K61 of the sixth switch K6, and the second end K72 of the seventh switch K7 is connected to any circuit point between the middle lines of the first capacitor C1 and the second capacitor C2.

8. The AC-DC conversion circuit of the motor according to claim 7, characterized in that: The switch action state of the input mode switching circuit corresponding to the three-phase power supply mode is: the first end K11 of the first switch K1 is turned on, the first end K21 of the second switch K2 is turned on, the third switch K3, the fourth switch K4, and the fifth switch K5 are turned on, and the sixth switch K6 and the seventh switch K7 are turned off; The single-phase power supply mode includes AN single-phase power supply mode, BN single-phase power supply mode and CN single-phase power supply mode, wherein: The switch action state of the input mode switching circuit corresponding to the AN single-phase power supply mode is: the third switch K3, the fourth switch K4, the second end K12 of the first switch K1, the seventh switch K7, and the sixth switch K6 are turned on, the first end K21 of the second switch K2 is turned on, and the fifth switch K5 is turned off, or the third switch K3, the fifth switch K5, the second end K22 of the second switch K2, the seventh switch K7, and the sixth switch K6 are turned on, the first end K11 of the first switch K1 is turned on, and the fourth switch K4 is turned off; The switch action state of the input mode switching circuit corresponding to the BN single-phase power supply mode is: the first end K11 of the first switch K1, the fourth switch K4, the fifth switch K5, the second end K22 of the second switch K2, the seventh switch K7, and the sixth switch K6 are turned on, and the third switch K3 is turned off; The switch action state of the input mode switching circuit corresponding to the CN single-phase power supply mode is: the first end K21 of the second switch K2, the fifth switch K5, the fourth switch K4, the second end K12 of the first switch K1, the seventh switch K7, and the sixth switch K6 are turned on, and the third switch K3 is turned off.

9. The AC-DC conversion circuit of the motor according to claim 8, characterized in that: The bus voltage V_bus of the rectifier circuit is determined by the uncontrolled rectifier voltage input by the three-phase current source in the three-phase power supply mode or the single-phase power supply mode; wherein, The maximum value V_in_max_3 and the minimum value V_in_min_3 of the input phase voltage of the three-phase current source in the three-phase power supply mode are respectively: V_in_max_3 = V_bus_max_3 / (√2 × √3), where the √ in √2 and √3 represents the square root operator; V_in_min_3=V_bus_min_3 / (√2×√3); Wherein, V_bus_max_3 is the real maximum value of the bus voltage V_bus of the rectifier circuit in the three-phase power supply mode, and V_bus_min_3 is the real minimum value of the bus voltage V_bus of the rectifier circuit in the three-phase power supply mode; The maximum value V_in_max_1 and the minimum value V_in_min_1 of the input phase voltage of the three-phase current source in the single-phase power supply mode are respectively: V_in_max_1=V_bus_max_1 / √2; V_in_min_1=V_bus_min_1 / 2√2; Among them, V_bus_max_1 is the real maximum value of the bus voltage V_bus of the rectifier circuit in the single-phase power supply mode, and V_bus_min_1 is the real minimum value of the bus voltage V_bus of the rectifier circuit in the single-phase power supply mode.

10. The AC-DC conversion circuit of the motor according to claim 9, characterized in that: If V_in_max_3=V_in_max_1, V_in_min_3=V_in_min_1, Then V_bus_max_ref = V_in_max_3 × √2 × √3, and V_bus_min_ref = V_in_min_1 × 2√2.

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