Three-phase four-wire system motor controller compatible with three-phase operation and two-phase operation and control system

Abstract

The invention discloses a three-phase four-wire system motor controller compatible with three-phase and two-phase operation and a control system, the three-phase four-wire system motor controller comprises a middle-line bridge arm, a three-phase bridge arm, a capacitor assembly, a middle bridge arm control module and a three-phase bridge arm control module, the output of the middle-line bridge arm is electrically connected with the neutral point of a three-phase four-wire system motor; three paths of outputs of the three-phase bridge arm are electrically connected with three-phase windings of the three-phase four-wire system motor respectively; the capacitor assembly is electrically connected with the positive electrode and the negative electrode of a direct current bus corresponding to the three-phase four-wire system motor controller. The middle bridge arm control module is used for controlling a middle line bridge arm; the three-phase bridge arm control module is used for controlling a three-phase bridge arm. When one phase of the three-phase four-wire system motor breaks down, the three-phase four-wire system motor can work in a two-phase operation mode by introducing the middle-line bridge arm and leading out the neutral point of the motor, so that the three-phase four-wire system motor can be compatible with the three-phase operation mode and the two-phase operation mode; therefore, safe redundancy of stable torque can be provided for the electric driving system.

Description

Technical Field

[0001] The present application relates to the field of motor technology, and in particular to a three-phase four-wire motor controller and control system that is compatible with three-phase and two-phase operation. Background Art

[0002] At present, the mainstream AC drive system adopts a three-phase three-wire system, that is, the inverter output and the motor input are both symmetrical three-phase AC, so the neutral line can be omitted. The existence of symmetrical three-phase AC is a prerequisite for the three-phase electric drive system to operate stably or output smooth torque. When a three-phase AC drive system has a phase failure, it cannot maintain stable operation, which is manifested as the motor cannot maintain a stable torque output. When a three-phase system has a phase failure, due to the constraint that the sum of the remaining two-phase winding currents is 0, the stator winding cannot generate a continuously rotating magnetomotive force wave in space. When a two-phase phase failure occurs, the third phase cannot work either.

[0003] With the widespread application of electric drive systems in intelligent equipment, such as self-driving cars or intelligent robots, the reliability requirements for electric drive systems are getting higher and higher, such as in application environments such as wire-controlled steering, wire-controlled braking, and safe operation intelligent robotic arms. If a three-phase electric drive system fails due to a phase failure, the result is often catastrophic. To address this problem, the mainstream solution in industry or academia is to increase the number of motor phases, such as an electric drive system consisting of a five-phase motor or a six-phase (dual three-phase) motor. However, more phases mean more power semiconductor device requirements and relatively complex electronic control systems, which greatly increases the cost of the system.

[0004] Therefore, how to increase the safety redundancy of the three-phase electric drive system in a low-cost manner is a problem that needs to be solved urgently. Summary of the invention

[0005] The main purpose of this application is to provide a three-phase four-wire motor controller and control system that is compatible with three-phase and two-phase operation, aiming to solve the technical problem of increasing the safety redundancy of a three-phase electric drive system in a low-cost manner.

[0006] To achieve the above object, the present application provides a three-phase four-wire motor controller compatible with three-phase and two-phase operation, and the three-phase four-wire motor controller compatible with three-phase and two-phase operation includes:

[0007] A neutral bridge arm, the output of which is electrically connected to the neutral point of the three-phase four-wire motor;

[0008] A three-phase bridge arm, wherein three outputs of the three-phase bridge arm are electrically connected to the three-phase windings of the three-phase four-wire motor respectively;

[0009] A capacitor assembly, wherein the capacitor assembly is electrically connected to a positive electrode and a negative electrode of a DC bus corresponding to the three-phase four-wire motor controller respectively;

[0010] An intermediate bridge arm control module, used for controlling the middle line bridge arm;

[0011] A three-phase bridge arm control module, used to control the three-phase bridge arm;

[0012] The three-phase four-wire motor controller compatible with three-phase and two-phase operation includes two topology solutions.

[0013] Furthermore, in the topology solution 1, the neutral bridge arm includes a first power switch tube and a second power switch tube, and the capacitor component includes a DC bus capacitor;

[0014] The drain of the first power switch tube is electrically connected to the source of the second power switch tube, the source of the first power switch tube is electrically connected to the positive electrode of the DC bus, and the drain of the second power switch tube is electrically connected to the negative electrode of the DC bus;

[0015] The neutral bridge arm is directly output to the neutral point, that is, the connection point between the drain of the first power switch tube and the source of the second power switch tube is electrically connected to the neutral point;

[0016] The DC bus capacitor is electrically connected to the positive electrode and the negative electrode of the DC bus respectively.

[0017] Furthermore, in the second topology solution, the neutral bridge arm includes a first power switch tube and a second power switch tube, and the capacitor component includes an upper and lower series capacitor formed by a first capacitor and a second capacitor;

[0018] The drain of the first power switch tube is electrically connected to the source of the second power switch tube, the source of the first power switch tube is electrically connected to the positive electrode of the DC bus, and the drain of the second power switch tube is electrically connected to the negative electrode of the DC bus;

[0019] The first capacitor of the upper and lower series capacitors is electrically connected to the positive electrode of the DC bus, and the second capacitor is electrically connected to the negative electrode of the DC bus;

[0020] The neutral bridge arm is output to the neutral point through the neutral inductor, that is, the connection point between the drain of the first power switch tube and the source of the second power switch tube is electrically connected to one end of the neutral inductor, the other end of the neutral inductor is electrically connected to the neutral point, and the connection point between the first capacitor and the second capacitor is electrically connected to the neutral point.

[0021] Further, the three-phase bridge arm includes a third power switch tube, a fourth power switch tube, a fifth power switch tube, a sixth power switch tube, a seventh power switch tube and an eighth power switch tube;

[0022] The drain of the third power switch tube is electrically connected to the source of the fourth power switch tube, the drain of the fifth power switch tube is electrically connected to the source of the sixth power switch tube, and the drain of the seventh power switch tube is electrically connected to the source of the eighth power switch tube;

[0023] The connection point between the drain of the third power switch tube and the source of the fourth power switch tube is electrically connected to the U-phase winding of the three-phase four-wire motor, the connection point between the drain of the fifth power switch tube and the source of the sixth power switch tube is electrically connected to the V-phase winding of the three-phase four-wire motor, and the connection point between the drain of the seventh power switch tube and the source of the eighth power switch tube is electrically connected to the W-phase winding of the three-phase four-wire motor;

[0024] The source electrode of the third power switch tube, the source electrode of the fifth power switch tube and the source electrode of the seventh power switch tube are electrically connected to the positive electrode of the DC bus respectively;

[0025] The drain of the fourth power switch tube, the drain of the sixth power switch tube and the drain of the eighth power switch tube are electrically connected to the negative electrode of the DC bus respectively.

[0026] Furthermore, when the three-phase four-wire motor is in a three-phase operation mode,

[0027] The middle bridge arm control module controls the first power switch tube and the second power switch tube to be in a closed state;

[0028] The three-phase bridge arm control module adopts vector control or direct torque control to control the three-way output of the three-phase bridge arm to drive the three-phase four-wire motor to operate in a three-phase operation mode.

[0029] Furthermore, in the topology scheme 1, when the three-phase four-wire motor is in the two-phase operation mode,

[0030] The intermediate bridge arm control module controls the first power switch tube and the second power switch tube of the neutral bridge arm through open-loop control or closed-loop control to control the voltage balance between the first average voltage and the second average voltage, wherein the first average voltage is the average voltage between the source and the drain of the first power switch tube, and the second average voltage is the average voltage between the source and the drain of the second power switch tube;

[0031] The three-phase bridge arm control module controls two outputs in the three-phase bridge arm to drive the three-phase four-wire motor to operate in a two-phase operation mode.

[0032] Furthermore, in the second topology scheme, when the three-phase four-wire motor is in the two-phase operation mode,

[0033] The intermediate bridge arm control module controls the first power switch tube and the second power switch tube of the neutral bridge arm through open-loop control or closed-loop control to control the voltage balance between the first capacitor and the second capacitor;

[0034] The three-phase bridge arm control module controls two outputs in the three-phase bridge arm to drive the three-phase four-wire motor to operate in a two-phase operation mode.

[0035] Furthermore, the three-phase four-wire motor controller compatible with three-phase and two-phase operation also includes a control module and a drive module;

[0036] The control module includes the middle bridge arm control module, the three-phase bridge arm control module and the phase loss detection module, which are used to control the three-phase four-wire motor to operate in a three-phase operation mode or a two-phase operation mode, and control the speed, torque, current, flux linkage and voltage of the three-phase four-wire motor;

[0037] The phase loss detection module is used to detect and determine the operation mode of the three-phase four-wire motor controller or the three-phase four-wire motor, and the operation mode includes a three-phase operation mode or a two-phase operation mode;

[0038] The driving module is electrically connected to the control module, the neutral bridge arm and the three-phase bridge arm respectively, and is used to receive a first driving signal for the neutral bridge arm and a second driving signal for the three-phase bridge arm output by the control module, amplify the driving power of the first driving signal and adjust the waveform of the first driving signal, output the obtained first target driving signal to the neutral bridge arm, amplify the driving power of the second driving signal and adjust the waveform of the second driving signal, and output the obtained second target driving signal to the three-phase bridge arm.

[0039] Further, when the three-phase four-wire motor runs forward and works in the three-phase operation mode, a symmetrical three-phase current is passed, and the V-phase current lags the U-phase current by 120°, and the W-phase current lags the U-phase current by 120°; when the three-phase four-wire motor runs negatively and works in the three-phase operation mode, a symmetrical three-phase current is passed, and the V-phase current leads the U-phase current by 120°, and the W-phase current leads the U-phase current by 120°;

[0040] When the three-phase four-wire motor runs forward and works in the two-phase operation mode, if the W-phase winding fails, the V-phase current needs to lag the U-phase current by 60°; if the U-phase winding fails, the W-phase current needs to lag the V-phase current by 60°; if the V-phase winding fails, the U-phase current needs to lag the W-phase current by 60°; when the three-phase four-wire motor runs negatively and works in the two-phase operation mode, if the W-phase winding fails, the V-phase current needs to lead the U-phase current by 60°; if the U-phase winding fails, the W-phase current needs to lead the V-phase current by 60°; if the V winding phase fails, the U-phase current needs to lead the W-phase current by 60°.

[0041] In addition, to achieve the above-mentioned purpose, the present application also provides a three-phase four-wire motor control system compatible with three-phase and two-phase operation, wherein the three-phase four-wire motor control system compatible with three-phase and two-phase operation includes a three-phase four-wire motor and the aforementioned three-phase four-wire motor controller compatible with three-phase and two-phase operation;

[0042] The three-phase four-wire motor leads out the neutral point, including four power lead wires of U, V, W and neutral line.

[0043] The three-phase four-wire motor proposed in the present application works exactly the same as a traditional three-phase motor when there is no phase loss fault. When one phase of the three-phase four-wire motor fails, the neutral line voltage is controlled by introducing a neutral line bridge arm control, so that the remaining two-phase currents of the three-phase four-wire motor can be independently controlled, and the two outputs in the three-phase bridge arm are controlled by the three-phase bridge arm control module so that the remaining two-phase current forms a rotating magnetomotive force wave, which can make the three-phase four-wire motor work in a two-phase operation mode and achieve a smooth torque output of the motor, thereby making the three-phase four-wire motor compatible with the three-phase operation mode and the two-phase operation mode, thereby providing safety redundancy for the electric drive system.

[0044] Compared with the existing three-phase electric drive system, the three-phase four-wire motor controller and three-phase four-wire motor proposed in this application are compatible with three-phase and two-phase operation. Only the neutral line is led out on the motor side, and only a half-bridge arm is added on the inverter side, which does not make much change to the existing three-phase system. In the three-phase operation mode, the performance is completely consistent with the existing three-phase electric drive system and a two-phase operation redundant mode that can output smooth torque is provided, with good safety redundancy performance.

[0045] Compared with the existing five-phase and six-phase (dual three-phase) electric drive systems, the three-phase four-wire motor controller and three-phase four-wire motor proposed in this application can greatly reduce the material and processing costs in both the controller and the motor, and have a high cost advantage. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0047] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0048] Figure 1 A schematic diagram of the circuit structure provided for the topology scheme 1 of the three-phase four-wire motor controller embodiment compatible with three-phase and two-phase operation of the present application;

[0049] Figure 2 A schematic diagram of the circuit structure provided for topology scheme 2 of the three-phase four-wire motor controller embodiment compatible with three-phase and two-phase operation of the present application;

[0050] Figure 3 A schematic diagram of the wiring of the three-phase four-wire motor windings in an embodiment of a three-phase four-wire motor control system compatible with three-phase and two-phase operation of the present application;

[0051] Figure 4 A schematic diagram of the three-phase operation results of a three-phase four-wire motor in topology solution 1 or 2 of an embodiment of the present application;

[0052] Figure 5 This is a schematic diagram of the two-phase control result of a three-phase four-wire motor in topology solution 1 of an embodiment of the present application;

[0053] Figure 6 This is a schematic diagram of the two-phase control result of a three-phase four-wire motor in topology solution 1 of an embodiment of the present application;

[0054] Figure 7 This is a schematic diagram of the two-phase control result of a three-phase four-wire motor in topology solution 2 of an embodiment of the present application;

[0055] Figure 8 This is a schematic diagram of the two-phase control results of the three-phase four-wire motor in topology scheme 2 of the embodiment of the present application.

[0056] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0057] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0058] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0059] In order to solve the technical problem of increasing the safety redundancy of the three-phase electric drive system in a low-cost manner, the main solution of the present application is: the output of the neutral bridge arm is electrically connected to the neutral point of the three-phase four-wire motor; the three outputs of the three-phase bridge arm are respectively electrically connected to the three-phase windings of the three-phase four-wire motor; the capacitor assembly is respectively electrically connected to the positive and negative poles of the DC bus corresponding to the three-phase four-wire motor controller; the intermediate bridge arm control module is used to control the neutral bridge arm; and the three-phase bridge arm control module is used to control the three-phase bridge arm.

[0060] At present, the mainstream AC drive system adopts a three-phase three-wire system, that is, the inverter output and the motor input are both symmetrical three-phase AC, so the neutral line can be omitted. The existence of symmetrical three-phase AC is a prerequisite for the three-phase electric drive system to operate stably or output smooth torque. When a three-phase AC drive system has a phase failure, it cannot maintain stable operation, which is manifested as the motor cannot maintain a stable torque output. When a three-phase system has a phase failure, due to the constraint that the sum of the remaining two-phase currents is 0, the stator winding cannot generate a continuously rotating magnetic motive force wave in space. When a two-phase phase failure occurs, the third phase cannot work either.

[0061] With the widespread application of electric drive systems in intelligent equipment, such as self-driving cars or intelligent robots, the reliability requirements of electric drive systems are getting higher and higher, such as in application environments such as wire-controlled steering, wire-controlled braking, and safe operation intelligent robotic arms. If a three-phase electric drive system fails due to a phase loss, the result is often catastrophic. To address this problem, the mainstream solution in industry or academia is to increase the number of motor phases, such as an electric drive system consisting of a five-phase motor or a six-phase (dual three-phase) motor. However, more phases mean more power semiconductor device requirements and relatively complex electronic control systems, which greatly increases the cost of the system. Therefore, how to make three-phase and two-phase operating modes compatible in a three-phase four-wire motor is a problem that needs to be solved urgently.

[0062] When one phase of a three-phase four-wire motor fails, the present application controls the neutral line voltage by introducing a neutral line bridge arm control, so that the remaining two-phase currents of the three-phase four-wire motor can be independently controlled, and controls the two outputs in the three-phase bridge arm through the three-phase bridge arm control module so that the remaining two-phase current forms a rotating magnetomotive force wave, which can make the three-phase four-wire motor operate in a two-phase operation mode and achieve smooth torque output of the motor, thereby making the three-phase four-wire motor compatible with the three-phase operation mode and the two-phase operation mode, thereby providing safety redundancy for the electric drive system.

[0063] Theoretical analysis 1: Synthetic rotating magnetomotive force wave of three-phase symmetrical winding and two-phase winding with a phase difference of 120°:

[0064] For a three-phase AC motor, if the U, V and W phases of the symmetrical winding of the three-phase AC motor differ by 120° in space, and the V and W phases lead by 120° and 240° respectively in space, then a symmetrical three-phase positive sequence AC current is passed through the three-phase winding of the motor:

[0065]

[0066] Among them, I φ is the current amplitude, ω is the current frequency, is the initial phase of the U-phase current, and the V-phase current and the W-phase current lag 120° respectively, which corresponds to the spatial consistency characteristics of "space advance and time lag" in the AC motor. The magnetic motive force formed by the three-phase winding can be superimposed by the magnetic motive force generated by each of the three-phase currents, and a pulsating magnetic motive force will be generated for the U-phase current.

[0067]

[0068] Among them, N s is the total number of series turns per phase, k d is the distribution factor, k p is the short distance factor, p is the pole pair number, is the spatial distribution angle, let

[0069]

[0070] Then the magnetomotive force generated by the U-phase winding can also be described by a space vector, which can be expressed as:

[0071]

[0072] Among them, e j0° It is spatially phase-consolidated with the U-phase winding.

[0073] Similarly, the magnetomotive force generated by the currents of phases V and W can also be described by space vectors:

[0074]

[0075] Among them, e j120° and e j240° It means that the V phase and W phase lead the U phase by 120° and 240° respectively in space, then the magnetomotive force of the three-phase winding is:

[0076]

[0077] Then we can get:

[0078]

[0079] Therefore, the synthetic magnetomotive force generated by the three-phase winding is a positive rotating magnetomotive force wave, whose rotation frequency is the excitation frequency of the current, and is used in the application scenario of the motor's positive rotation. Similarly, if the three-phase winding is passed with a negative sequence current, a negative rotating magnetomotive force wave is generated, which can be used in the application scenario of the motor's negative rotation.

[0080] If a three-phase motor has a phase failure, only two phases of windings are left, and the phase difference between the remaining two phases is still 120°. The magnetomotive force generated is analyzed below. Assume that the W phase has a fault and the current passing through the three-phase motor is as follows:

[0081]

[0082] Among them, θ is the phase difference between the V-phase current and the U-phase current. The W-phase is the fault phase, and its current is 0. The U-phase current is still fixed to the spatial position of the U-phase, and the V-phase current is still fixed to the spatial position of the V-phase. The magnetic motive force generated by the currents of the U-phase and V-phase can be expressed as:

[0083]

[0084] At this time, the magnetomotive force of the U and V phase windings is:

[0085]

[0086] Similar to the three-phase case, we expect f s (t) is a positive rotating magnetomotive force wave, which is used in the application scenario of the motor rotating in the forward direction. Partially offset each other, that is, it is necessary to meet:

[0087] e j0° +e j(120°-θ) =0;

[0088] Therefore, θ=-60°, that is, the V-phase current lags the U-phase current by 60°. At this time:

[0089]

[0090] It can be seen that the amplitude of the synthetic rotating magnetomotive force wave of the two-phase winding with a current difference of 60° is reduced compared with the symmetrical three-phase winding and the synthetic rotating magnetomotive force. times. If you want to achieve the same magnetomotive force effect, you need to increase the current of the two-phase winding by As expected f s (t) is a positive rotating magnetomotive force wave, then θ = 60°, making the positive rotating They cancel each other out and are used in applications where the motor rotates in the negative direction.

[0091] Similarly, if we expect f s(t) is a positive rotating magnetomotive force wave. If a fault occurs in the U phase, the W phase current must lag behind the V phase current by 60°; if a fault occurs in the V phase, the U phase current must lag behind the W phase current by 60°. s (t) is a negative rotating magnetomotive force wave. If a fault occurs in the U phase, the W phase current must lead the V phase current by 60°; if a fault occurs in the V phase, the U phase current must lead the W phase current by 60°. The current phase difference between the two-phase windings is 60°, which is an asymmetric current, so the sum of the two-phase current is not 0.

[0092] Therefore, the two-phase current cannot be controlled by using the traditional motor control topology.

[0093] Theoretical Analysis 2: Coordinate Transformation of Three-Phase Winding and Two-Phase Winding with 120° Phase Difference

[0094] The three-phase current of the three-phase motor is AC, which is not easy to analyze and control, so coordinate transformation is needed. After Clark transformation, the three-phase current of the ABC axis system is transformed into the two-phase current of the αβ axis system, which is:

[0095]

[0096] Among them, i α is the phase current corresponding to the α axis, i β is the phase current corresponding to the β axis, and then the two-phase current of the αβ axis system is:

[0097]

[0098] The magnetic field synchronously rotates the MT motion axis system, where the spatial angle between the MT motion axis system and the αβ orthogonal axis system is θ M It can be obtained by integration:

[0099] θ M =∫ωdt+ρ0;

[0100] Among them, ρ0 is the initial phase angle of the MT coordinate system relative to the stationary coordinate system. Then there is Park transformation:

[0101]

[0102] In the sinusoidal steady state, the MT axis rotates at a constant speed, θ M =ωt+ρ0, we can get:

[0103]

[0104] The above formula shows that i M and i MIt has been converted into a DC quantity, that is, through Clark transformation and Park transformation, the three-phase current of the ABC axis system can be transformed into the magnetic field synchronous rotating MT axis system, and the symmetrical sinusoidal current in the stator three-phase winding has been transformed into a constant DC in the stator two-phase winding of the MT axis system. When the three-phase current is negative sequence, the DC current of the MT axis system can also be obtained by coordinate transformation.

[0105] When a phase failure occurs, the coordinate transformation relationship of the two-phase winding with a phase difference of 120° is as follows:

[0106] Assuming that a fault occurs in phase W, the three-phase motor current is:

[0107]

[0108] And then:

[0109]

[0110] After further Park transformation, we have:

[0111]

[0112] Therefore, the two-phase current of the two-phase winding with a phase difference of 120° can also be obtained through Clark transformation and Park transformation to obtain the constant DC in the two-phase winding of the MT shaft system stator. If the V-phase current leads the W-phase current by 60°, the DC current of the MT shaft system can also be obtained by coordinate transformation. The same analysis method can be used to analyze the situation of phase loss of U phase and V phase.

[0113] Theoretical Analysis 3: Torque Equation

[0114] According to the vector equation of torque, that is, the electromagnetic torque is equal to the product of the orthogonal components of the stator and rotor flux, it can also be converted into the vector product (cross product) of the stator flux vector and the current vector. In the MT coordinate system,

[0115]

[0116] The magnetic flux expression can be expressed as:

[0117] ψ M =L M i M +L Mm i m ;

[0118] ψ T =L T i T +L Tt i t ;

[0119] Among them, i M, iT is the equivalent excitation current on the rotor side, L M , L T is the self-inductance of the stator in the MT coordinate system, L Mm , L Tt are the mutual inductance of the stator and rotor on the M axis and T axis in the MT coordinate system. M , L T and mutual inductance L Mm , L Tt It is not the excitation inductance between physical coils in the actual sense, but a "virtual" inductance obtained after mathematical transformation, also known as "synchronous inductance".

[0120] Further, the basic equation of the motor torque can be obtained:

[0121] t e =(L M -L T )i M i T +L Mm i m i T -L Tt i t i M ;

[0122] Consider a three-phase motor application, the torque equation is:

[0123]

[0124] Among them, 3 / 2 is the coefficient introduced by the change of magnetic common energy after the three-phase transformation of the two phases, and p0 is the number of pole pairs. It can be seen that in the MT coordinate system, the torque of the motor can be expressed as the relationship between the synchronous inductance and the current. Similarly, in the case of a two-phase winding difference, the torque equation can be expressed as:

[0125] t e = p0[(L M -L T )i M i T +L Mm i m i T -L Tt i t i M ];

[0126] From the torque equation (considering i M 、i T When the rotor excitation is consistent, compared with the three-phase, the torque of the two-phase winding motor with a phase difference of 120° is also reduced compared with the torque of the three-phase winding motor with the same stator AC current amplitude. times, which is consistent with the reduction in the amplitude of the magnetomotive force. If the rotor has a salient pole effect, then L M ≠LT, there is reluctance torque. If the rotor is a hidden pole rotor, then L M =L T , the reluctance torque phase is 0. For salient pole rotors or non-salient pole rotors, the above phase loss analysis process is applicable.

[0127] Implementation Example: Topology Solution

[0128] Based on this, the present application proposes two topology solutions of the three-phase four-wire motor controller compatible with three-phase and two-phase operation of the first embodiment, please refer to Figure 1 as well as Figure 2 , a three-phase four-wire motor controller compatible with three-phase and two-phase operation includes: a neutral bridge arm, a three-phase bridge arm, a capacitor component, an intermediate bridge arm control module and a three-phase bridge arm control module;

[0129] The output of the neutral bridge arm is electrically connected to the neutral point of the three-phase four-wire motor; the three outputs of the three-phase bridge arm are respectively electrically connected to the three-phase windings of the three-phase four-wire motor; the capacitor components are respectively electrically connected to the positive and negative electrodes of the DC bus corresponding to the three-phase four-wire motor controller; the intermediate bridge arm control module is used to control the neutral bridge arm; and the three-phase bridge arm control module is used to control the three-phase bridge arm.

[0130] Furthermore, if Figure 1 As shown, in topology scheme 1 of a three-phase four-wire motor controller compatible with three-phase and two-phase operation, the neutral bridge arm includes a first power switch tube S1 and a second power switch tube S2, and the capacitor component includes a DC bus capacitor C.

[0131] The drain of the first power switch tube S1 is electrically connected to the source of the second power switch tube S2, the source of the first power switch tube S1 is electrically connected to the positive electrode DC+ of the DC bus, and the drain of the second power switch tube S2 is electrically connected to the negative electrode DC- of the DC bus. Figure 1 As shown, the neutral bridge arm is directly output to the neutral point N, the connection point between the drain of the first power switch tube S1 and the source of the second power switch tube S2 is electrically connected to the neutral point N, and the connection line between the connection point and the neutral point N is the neutral line. The DC bus capacitor C is electrically connected to the positive electrode DC+ and the negative electrode DC- of the DC bus respectively, so that the DC bus capacitor C is directly connected across the positive and negative electrodes of the DC bus.

[0132] Furthermore, in the implementation example topology solution 1, as Figure 1As shown, the neutral bridge arm includes the first power switch tube S1 and the second power switch tube S2, and the three-phase bridge arm includes the third power switch tube S3, the fourth power switch tube S4, the fifth power switch tube S5, the sixth power switch tube S6, the seventh power switch tube S7 and the eighth power switch tube S8. Among them, the three-phase four-wire motor leads the neutral point, including four power lead wires of U, V, W and neutral line, for example, Figure 3 As shown, the neutral point is led out to form a neutral line (power lead line) N, and the U phase, V phase, and W phase are led out to form a U phase power lead line, a V phase power lead line, and a W phase power lead line, respectively.

[0133] The neutral point N is the center connection point N of the three-phase four-wire motor or is electrically connected to the center connection point N.

[0134] Among them, the power switch tubes S1~S8 can be power triodes, gate turn-off thyristors (GTOs), power transistors (GTRs), power field effect transistors (MOSFETs), and insulated gate bipolar transistors (IGBTs); the power switch tubes S1~S8 have their own reverse power diodes, or reverse power diodes are connected in parallel.

[0135] The drain of the third power switch tube S3 is electrically connected to the source of the fourth power switch tube S4, the drain of the fifth power switch tube S5 is electrically connected to the source of the sixth power switch tube S6, and the drain of the seventh power switch tube S7 is electrically connected to the source of the eighth power switch tube S8.

[0136] like Figure 1 and Figure 3 As shown, the connection point of the drain of the third power switch tube S3 and the source of the fourth power switch tube S4 is electrically connected to the U-phase winding of the three-phase four-wire motor, the connection point of the drain of the fifth power switch tube S5 and the source of the sixth power switch tube S6 is electrically connected to the V-phase winding of the three-phase four-wire motor, and the connection point of the drain of the seventh power switch tube S7 and the source of the eighth power switch tube S8 is electrically connected to the W-phase winding of the three-phase four-wire motor.

[0137] The source of the third power switch tube S3, the source of the fifth power switch tube S5 and the source of the seventh power switch tube S7 are respectively connected to the positive electrode DC+ of the DC bus; the drain of the fourth power switch tube S4, the drain of the sixth power switch tube S6 and the drain of the eighth power switch tube S8 are respectively connected to the negative electrode DC+ of the DC bus.

[0138] Furthermore, in the implementation example topology solution 1, as Figure 1As shown, when the three-phase four-wire motor is in the three-phase operation mode, the middle bridge arm control module controls the first power switch tube S1 and the second power switch tube S2 to be in the off state; the three-phase bridge arm control module adopts vector control or direct torque control to control the three-way output of the three-phase bridge arm to drive the three-phase four-wire motor to operate in the three-phase operation mode. Specifically, the three-phase bridge arm control module adopts vector control or direct torque control to control the third power switch tube S3 to the eighth power switch tube S8, and drives the three-phase motor to operate in the three-phase operation mode through the three-way output of the three-phase bridge arm.

[0139] When the three-phase four-wire motor is in the two-phase operation mode, the middle bridge arm control module controls the first power switch tube S1 and the second power switch tube S2 of the middle bridge arm through open-loop control or closed-loop control to control the voltage balance between the first average voltage and the second average voltage, wherein the first average voltage is the average voltage between the source and the drain of the first power switch tube S1, and the second average voltage is the average voltage between the source and the drain of the second power switch tube S2.

[0140] The three-phase bridge arm control module controls the two outputs in the three-phase bridge arm to drive the three-phase four-wire motor to operate in a two-phase operation mode. Specifically, the three-phase bridge arm control module controls the third power switch tube S3 to the eighth power switch tube S8, and drives the three-phase motor to operate in a two-phase operation mode through the two outputs of the three-phase bridge arm.

[0141] Among them, when the three-phase four-wire motor runs forward and works in the three-phase operation mode, a symmetrical three-phase current is passed, and the V-phase current lags the U-phase current by 120°, and the W-phase current lags the U-phase current by 120°; when the three-phase four-wire motor runs forward and works in the two-phase operation mode, if the W-phase winding fails, the V-phase current needs to lag the U-phase current by 60°; if the U-phase winding fails, the W-phase current needs to lag the V-phase current by 60°; if the V-phase winding fails, the U-phase current needs to lag the W-phase current by 60°.

[0142] When the three-phase four-wire motor runs in the negative direction and works in the three-phase operation mode, a symmetrical three-phase current is passed through, and the V-phase current leads the U-phase current by 120°, and the W-phase current leads the U-phase current by 120°; when the three-phase four-wire motor runs in the negative direction and works in the two-phase operation mode, if the W-phase winding fails, the V-phase current must lead the U-phase current by 60°; if the U-phase winding fails, the W-phase current must lead the V-phase current by 60°; if the V winding phase fails, the U-phase current must lead the W-phase current by 60°.

[0143] Furthermore, if Figure 2As shown, in topology scheme 2 of a three-phase four-wire motor controller compatible with three-phase and two-phase operation, the neutral bridge arm includes a first power switch tube S1 and a second power switch tube S2, and the capacitor component includes an upper and lower series capacitor formed by a first capacitor C1 and a second capacitor C2.

[0144] The drain of the first power switch tube S1 is electrically connected to the source of the second power switch tube S2, the source of the first power switch tube S1 is electrically connected to the positive electrode DC+ of the DC bus, and the drain of the second power switch tube S2 is electrically connected to the negative electrode DC- of the DC bus.

[0145] The first capacitor C1 of the upper and lower series capacitors is electrically connected to the positive pole DC+ of the DC bus, and the second capacitor C2 is electrically connected to the negative pole DC- of the DC bus, that is, the first capacitor C1 is connected across the positive pole DC+ of the DC bus and the neutral line, and the second capacitor C2 is connected across the neutral line and the negative pole DC- of the DC bus.

[0146] like Figure 2 As shown, the neutral bridge arm is output to the neutral point through the neutral inductor, that is, the connection point between the drain of the first power switch tube S1 and the source of the second power switch tube S2 is electrically connected to one end of the neutral inductor L, and the other end of the neutral inductor L is electrically connected to the neutral point.

[0147] like Figure 2 As shown, the neutral bridge arm includes the first power switch tube S1 and the second power switch tube S2, and the three-phase bridge arm includes the third power switch tube S3, the fourth power switch tube S4, the fifth power switch tube S5, the sixth power switch tube S6, the seventh power switch tube S7 and the eighth power switch tube S8. Among them, the three-phase four-wire motor leads the neutral point, including four power lead wires of U, V, W and neutral line, for example, Figure 3 As shown, the neutral point is led out to form a neutral line (power lead line) N, and the U phase, V phase, and W phase are led out to form a U phase power lead line, a V phase power lead line, and a W phase power lead line, respectively.

[0148] Among them, the drain of the third power switch tube S3 is electrically connected to the source of the fourth power switch tube S4, the drain of the fifth power switch tube S5 is electrically connected to the source of the sixth power switch tube S6, and the drain S7 of the seventh power switch tube is electrically connected to the source of the eighth power switch tube S8.

[0149] like Figure 3 As shown, the connection point of the drain of the third power switch tube S3 and the source of the fourth power switch tube S4 is electrically connected to the U-phase winding of the three-phase four-wire motor, the connection point of the drain of the fifth power switch tube S5 and the source of the sixth power switch tube S6 is electrically connected to the V-phase winding of the three-phase four-wire motor, and the connection point of the drain of the seventh power switch tube S7 and the source of the eighth power switch tube S8 is electrically connected to the W-phase winding of the three-phase four-wire motor.

[0150] The source of the third power switch tube S3, the source of the fifth power switch tube S5 and the source of the seventh power switch tube S7 are respectively connected to the positive electrode DC+ of the DC bus; the drain of the fourth power switch tube S4, the drain of the sixth power switch tube S6 and the drain of the eighth power switch tube S8 are respectively connected to the negative electrode DC+ of the DC bus.

[0151] Among them, the power switch tubes S1~S8 can be power triodes, gate turn-off thyristors (GTOs), power transistors (GTRs), power field effect transistors (MOSFETs), and insulated gate bipolar transistors (IGBTs); the power switch tubes S1~S8 have their own reverse power diodes, or reverse power diodes are connected in parallel.

[0152] Further, in the implementation example topology solution 2, if Figure 2 As shown, when the three-phase four-wire motor is in the three-phase operation mode, the middle bridge arm control module controls the first power switch tube S1 and the second power switch tube S2 to be in the off state; the three-phase bridge arm control module adopts vector control or direct torque control to control the three-way output of the three-phase bridge arm to drive the three-phase four-wire motor to operate in the three-phase operation mode. Specifically, the three-phase bridge arm control module adopts vector control or direct torque control to control the third power switch tube S3 to the eighth power switch tube S8, and drives the three-phase motor to operate in the three-phase operation mode through the three-way output of the three-phase bridge arm.

[0153] like Figure 2 As shown, when the three-phase four-wire motor is in the two-phase operation mode, the middle bridge arm control module controls the first power switch tube S1 and the second power switch tube S2 of the middle bridge arm through open-loop control or closed-loop control to control the voltage balance between the first capacitor C1 and the second capacitor C2. The three-phase bridge arm control module controls the two outputs in the three-phase bridge arm to drive the three-phase four-wire motor to work in the two-phase operation mode. Specifically, the three-phase bridge arm control module controls the third power switch tube S3 to the eighth power switch tube S8, and drives the three-phase motor to work in the two-phase operation mode through the two outputs of the three-phase bridge arm.

[0154] Among them, when the three-phase four-wire motor runs forward and works in the three-phase operation mode, it is passed with symmetrical three-phase current, and the V-phase current lags the U-phase current by 120°, and the W-phase current lags the U-phase current by 120°; when the three-phase four-wire motor runs negatively and works in the three-phase operation mode, it is passed with symmetrical three-phase current, and the V-phase current leads the U-phase current by 120°, and the W-phase current leads the U-phase current by 120°;

[0155] When the three-phase four-wire motor runs forward and works in the two-phase operation mode, if the W-phase winding fails, the V-phase current needs to lag behind the U-phase current by 60°; if the U-phase winding fails, the W-phase current needs to lag behind the V-phase current by 60°; if the V-phase winding fails, the U-phase current needs to lag behind the W-phase current by 60°; when the three-phase four-wire motor runs negatively and works in the two-phase operation mode, if the W-phase winding fails, the V-phase current needs to lead the U-phase current by 60°; if the U-phase winding fails, the W-phase current needs to lead the V-phase current by 60°; if the V winding fails, the U-phase current needs to lead the W-phase current by 60°.

[0156] Furthermore, in a feasible implementation manner, the three-phase four-wire motor controller compatible with three-phase and two-phase operation also includes a control module and a drive module.

[0157] The control module includes an intermediate bridge arm control module, a three-phase bridge arm control module and a phase loss detection module. The control module is used to control the three-phase four-wire motor to operate in a three-phase operation mode or a two-phase operation mode, and to control the speed, torque, current, flux linkage and voltage of the three-phase four-wire motor.

[0158] The phase loss detection module is used to detect and determine the operation mode of the three-phase four-wire motor controller or the three-phase four-wire motor, and the operation mode includes a three-phase operation mode or a two-phase operation mode.

[0159] The driving module is electrically connected to the control module, the neutral bridge arm and the three-phase bridge arm, respectively. The driving module is used to receive the first driving signal for the neutral bridge arm and the second driving signal for the three-phase bridge arm output by the control module. The driving module amplifies the driving power of the first driving signal and adjusts the waveform of the first driving signal, and outputs the obtained first target driving signal to the neutral bridge arm. The driving module is also used to receive the second driving signal for the three-phase bridge arm output by the control module. The driving module amplifies the driving power of the second driving signal and adjusts the waveform of the second driving signal, and outputs the obtained second target driving signal to the three-phase bridge arm. Furthermore, if any one of the U, V, and W phases of the three-phase four-wire motor fails in phase loss, the three-phase four-wire motor can be driven to enter a two-phase state for operation.

[0160] The three-phase four-wire motor controller proposed in this embodiment is compatible with three-phase and two-phase operation. When one phase of the three-phase four-wire motor fails, the neutral bridge arm is controlled by the middle bridge arm control module and the three-phase bridge arm is controlled by the three-phase bridge arm control module. By introducing the neutral bridge arm and the neutral point of the motor neutral line, the remaining two-phase currents can be controlled independently, so that the three-phase four-wire motor can operate in the two-phase operation mode and achieve smooth torque output of the motor, thereby making the three-phase four-wire motor compatible with the three-phase operation mode and the two-phase operation mode, thereby providing safety redundancy for the electric drive system.

[0161] Compared with the existing three-phase electric drive system, the present application is compatible with three-phase four-wire motors under three-phase and two-phase three-phase four-wire motor controllers. In the three-phase operation mode, the performance is completely consistent with the existing three-phase electric drive system. Compared with the existing five-phase and six-phase (dual three-phase) electric drive systems, the present application only leads out the neutral line on the motor side and only adds a half-bridge arm on the inverter side, which has a lower implementation cost.

[0162] Implementation example: Computer simulation

[0163] The following takes a three-phase four-wire electric drive based on a permanent magnet synchronous motor as an example. For a permanent magnet synchronous motor, i m =0,ψ f =L Tt i t is the permanent magnet flux, then the torque equation of the three-phase operation of the permanent magnet synchronous motor is:

[0164]

[0165] The torque equation for two-phase operation is:

[0166] t e = p0[(L M -L T )i M i T +ψ f i T ];

[0167] The parameters of permanent magnet synchronous motor are as follows:

[0168] Table 1: Parameters of permanent magnet synchronous motor

[0169]

[0170] The three-phase operation of the three-phase four-wire motor in the topology scheme 1 or 2 of the embodiment of the present application adopts the traditional vector control method, and the three-phase operation result is as follows: Figure 4 Its torque control target is 200Nm. Under traditional vector control, the motor torque can quickly reach the torque target, and the motor speed quickly reaches 3900rpm. Figure 4 (a) and 4(b). Traditional vector control has good current tracking capability, such as Figure 4 (c) and 4(d), the corresponding MT axis voltage is as follows: Figure 4 As shown in (e), the T-axis voltage is mainly used to balance the induced electromotive force caused by the increase in motor speed. In the three-phase operation mode, the neutral line is in a closed state, so the neutral line current is 0, such as Figure 4 (f) The transient current of the three-phase balance is as follows Figure 4(g) and 4(h), the current amplitude at this time reaches 400A. The control voltage of the three-phase balance is as follows Figure 4 As shown in (i) and 4(j), the control voltage using vector control is a saddle wave with an amplitude of 90V.

[0171] Assuming that a fault occurs in phase W, the two-phase control result of topology scheme 1 is as follows: Figure 5 and Figure 6 Its torque control target is still 200Nm. Under two-phase control, the motor torque can also quickly reach the torque target, and the motor speed quickly reaches 3900rpm, as shown in Figure 2. Figure 5 (a) and 4(b). The AC current in the two-phase control mode is shown as Figure 5 (c) to (f), it can be seen that the two-phase AC current control also has a good current tracking capability. The amplified three-phase instantaneous current is as follows Figure 6 (h) where i V Current ratio i U The current phase lags by 60°, which is consistent with the above theoretical analysis. V and i U The current reaches 600A, then the neutral current is i V with i U After the current. The three-phase control voltage is as follows Figure 6 (i) and 6(k), the required voltage amplitude is 200 V. The neutral line control of scheme 1 is open-loop control, and its duty cycle is 0.5, as shown in Figure 6 (1). The neutral voltage (after filtering) is as follows Figure 6 As shown in (k), the neutral voltage can achieve a good voltage balance.

[0172] Assuming that phase W fails, the two-phase control result of topology scheme 2 is as follows: Figure 7 and Figure 8 Its torque control target is still 200Nm. Under two-phase control, the motor torque can also quickly reach the torque target, and the motor speed quickly reaches 3900rpm, as shown in Figure 2. Figure 7 (a) and 7(b). The AC current in the two-phase control mode is shown as Figure 7 (c) to 7(f), it can be seen that the two-phase AC current control also has a good current tracking capability. The amplified three-phase instantaneous current is as follows Figure 8 (h) shown in which i V Current ratio i U The current phase lags by 60°, which is consistent with the above theoretical analysis. V and i U The current reaches 600A, then the neutral current is i V with i UAfter the current. The three-phase control voltage is as follows Figure 8 (i) and 8(k), the required voltage amplitude is 200 V. The neutral line control of Scheme 2 is a closed-loop voltage control, and its duty cycle fluctuates around 0.5, such as Figure 6 (l). The neutral voltage is Figure 6 As shown in (k), the neutral voltage can achieve a good voltage balance.

[0173] Comparing the results of the three-phase operation mode and the two-phase operation mode, it can be seen that to produce the same torque, the two-phase mode needs to pay more current. According to the results of the magnetomotive force analysis, the required current amplitude in the two-phase mode should be However, considering the existence of magnetic resistance torque, the actual required current amplitude in two-phase mode is about 1.5 times that in three-phase mode, which is reasonable. And the voltage in two-phase operation mode is much higher than that in single-phase mode.

[0174] Comparing the operation modes of topology scheme 1 and topology scheme 2, it can be seen that topology scheme 1 does not use neutral line inductance, and adopts open-loop control of the neutral line bridge arm to have a better neutral line balanced voltage (this voltage is the filtered voltage). Topology scheme 2 uses neutral line inductance and closed-loop neutral line voltage control, and the voltage amplitude is slightly larger (this voltage is the real voltage).

[0175] The present invention also proposes a three-phase four-wire motor, which includes a three-phase four-wire motor and a three-phase four-wire motor controller compatible with three-phase and two-phase operation. The specific structure of the three-phase four-wire motor controller compatible with three-phase and two-phase operation refers to the above embodiment. Since the three-phase four-wire motor adopts all the technical solutions of all the above embodiments, it also has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here one by one.

[0176] Among them, Figure 3 As shown, the three-phase four-wire motor leads out the neutral point, including four power lead lines U, V, W, and neutral line N.

[0177] It should be noted that the technical solutions of the various embodiments of the present invention can be combined with each other, but it must be based on the fact that technical personnel in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0178] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A three-phase four-wire motor controller compatible with three-phase and two-phase operation, characterized in that: The three-phase four-wire motor controller compatible with three-phase and two-phase operation includes: A neutral bridge arm, the output of which is electrically connected to the neutral point of the three-phase four-wire motor; A three-phase bridge arm, wherein three outputs of the three-phase bridge arm are electrically connected to the three-phase windings of the three-phase four-wire motor respectively; A capacitor assembly, wherein the capacitor assembly is electrically connected to a positive electrode and a negative electrode of a DC bus corresponding to the three-phase four-wire motor controller respectively; An intermediate bridge arm control module, used for controlling the middle line bridge arm; The three-phase bridge arm control module is used to control the three-phase bridge arm.

2. The three-phase four-wire motor controller compatible with three-phase and two-phase operation as claimed in claim 1, characterized in that: The neutral bridge arm includes a first power switch tube and a second power switch tube, and the capacitor assembly includes a DC bus capacitor; The drain of the first power switch tube is electrically connected to the source of the second power switch tube, the source of the first power switch tube is electrically connected to the positive electrode of the DC bus, and the drain of the second power switch tube is electrically connected to the negative electrode of the DC bus; The neutral bridge arm is directly output to the neutral point, that is, the connection point between the drain of the first power switch tube and the source of the second power switch tube is electrically connected to the neutral point; The DC bus capacitor is electrically connected to the positive electrode and the negative electrode of the DC bus respectively.

3. The three-phase four-wire motor controller compatible with three-phase and two-phase operation as claimed in claim 1, characterized in that: The midline bridge arm includes a first power switch tube and a second power switch tube, and the capacitor assembly includes an upper and lower series capacitor formed by a first capacitor and a second capacitor; The drain of the first power switch tube is electrically connected to the source of the second power switch tube, the source of the first power switch tube is electrically connected to the positive electrode of the DC bus, and the drain of the second power switch tube is electrically connected to the negative electrode of the DC bus; The first capacitor of the upper and lower series capacitors is electrically connected to the positive electrode of the DC bus, and the second capacitor is electrically connected to the negative electrode of the DC bus; The neutral bridge arm is output to the neutral point through the neutral inductor, that is, the connection point between the drain of the first power switch tube and the source of the second power switch tube is electrically connected to one end of the neutral inductor, and the other end of the neutral inductor is electrically connected to the neutral point; A connection point between the first capacitor and the second capacitor is electrically connected to the neutral point.

4. The three-phase four-wire motor controller compatible with three-phase and two-phase operation as claimed in claim 2 or 3, characterized in that: The three-phase bridge arm includes a third power switch tube, a fourth power switch tube, a fifth power switch tube, a sixth power switch tube, a seventh power switch tube and an eighth power switch tube; The drain of the third power switch tube is electrically connected to the source of the fourth power switch tube, the drain of the fifth power switch tube is electrically connected to the source of the sixth power switch tube, and the drain of the seventh power switch tube is electrically connected to the source of the eighth power switch tube; The connection point between the drain of the third power switch tube and the source of the fourth power switch tube is electrically connected to the U-phase winding of the three-phase four-wire motor, the connection point between the drain of the fifth power switch tube and the source of the sixth power switch tube is electrically connected to the V-phase winding of the three-phase four-wire motor, and the connection point between the drain of the seventh power switch tube and the source of the eighth power switch tube is electrically connected to the W-phase winding of the three-phase four-wire motor; The source electrode of the third power switch tube, the source electrode of the fifth power switch tube and the source electrode of the seventh power switch tube are electrically connected to the positive electrode of the DC bus respectively; The drain of the fourth power switch tube, the drain of the sixth power switch tube and the drain of the eighth power switch tube are electrically connected to the negative electrode of the DC bus respectively.

5. The three-phase four-wire motor controller compatible with three-phase and two-phase operation as claimed in claim 2 or 3, characterized in that: When the three-phase four-wire motor is in a three-phase operation mode, The middle bridge arm control module controls the first power switch tube and the second power switch tube to be in a closed state; The three-phase bridge arm control module adopts vector control or direct torque control to control the three-way output of the three-phase bridge arm to drive the three-phase four-wire motor to operate in a three-phase operation mode.

6. The three-phase four-wire motor controller compatible with three-phase and two-phase operation as claimed in claim 2, characterized in that: When the three-phase four-wire motor is in a two-phase operation mode, The intermediate bridge arm control module controls the first power switch tube and the second power switch tube of the neutral bridge arm through open-loop control or closed-loop control to control the voltage balance between the first average voltage and the second average voltage, wherein the first average voltage is the average voltage between the source and the drain of the first power switch tube, and the second average voltage is the average voltage between the source and the drain of the second power switch tube; The three-phase bridge arm control module controls two outputs in the three-phase bridge arm to drive the three-phase four-wire motor to operate in a two-phase operation mode.

7. The three-phase four-wire motor controller compatible with three-phase and two-phase operation as claimed in claim 3, characterized in that: When the three-phase four-wire motor is in a two-phase operation mode, The intermediate bridge arm control module controls the first power switch tube and the second power switch tube of the neutral bridge arm through open-loop control or closed-loop control to control the voltage balance between the first capacitor and the second capacitor; The three-phase bridge arm control module controls two outputs in the three-phase bridge arm to drive the three-phase four-wire motor to operate in a two-phase operation mode.

8. The three-phase four-wire motor controller compatible with three-phase and two-phase operation according to any one of claims 1 to 7, characterized in that: The three-phase four-wire motor controller compatible with three-phase and two-phase operation also includes a control module and a drive module; The control module includes the middle bridge arm control module, the three-phase bridge arm control module and the phase loss detection module, which are used to control the three-phase four-wire motor to operate in a three-phase operation mode or a two-phase operation mode, and control the speed, torque, current, flux linkage and voltage of the three-phase four-wire motor; The phase loss detection module is used to detect and determine the operation mode of the three-phase four-wire motor controller or the three-phase four-wire motor, and the operation mode includes a three-phase operation mode or a two-phase operation mode; The driving module is electrically connected to the control module, the neutral bridge arm and the three-phase bridge arm respectively, and is used to receive a first driving signal for the neutral bridge arm and a second driving signal for the three-phase bridge arm output by the control module, amplify the driving power of the first driving signal and adjust the waveform of the first driving signal, output the obtained first target driving signal to the neutral bridge arm, amplify the driving power of the second driving signal and adjust the waveform of the second driving signal, and output the obtained second target driving signal to the three-phase bridge arm.

9. The three-phase four-wire motor controller compatible with three-phase and two-phase operation as claimed in claim 8, characterized in that: When the three-phase four-wire motor runs forward and works in the three-phase operation mode, a symmetrical three-phase current is passed, and the V-phase current lags the U-phase current by 120°, and the W-phase current lags the U-phase current by 120°; when the three-phase four-wire motor runs negatively and works in the three-phase operation mode, a symmetrical three-phase current is passed, and the V-phase current leads the U-phase current by 120°, and the W-phase current leads the U-phase current by 120°; When the three-phase four-wire motor runs forward and works in the two-phase operation mode, if the W-phase winding fails, the V-phase current needs to lag the U-phase current by 60°; if the U-phase winding fails, the W-phase current needs to lag the V-phase current by 60°; if the V-phase winding fails, the U-phase current needs to lag the W-phase current by 60°; when the three-phase four-wire motor runs negatively and works in the two-phase operation mode, if the W-phase winding fails, the V-phase current needs to lead the U-phase current by 60°; if the U-phase winding fails, the W-phase current needs to lead the V-phase current by 60°; if the V winding phase fails, the U-phase current needs to lead the W-phase current by 60°.

10. A three-phase four-wire motor control system compatible with three-phase and two-phase operation, characterized in that: The three-phase four-wire motor control system compatible with three-phase and two-phase operation comprises a three-phase four-wire motor and a three-phase four-wire motor controller compatible with three-phase and two-phase operation according to any one of claims 1 to 9; The three-phase four-wire motor leads out the neutral point, including four power lead-out lines of U, V, W and neutral line.

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