Motor excitation loss fault detection method and device, vehicle, medium and program product

Abstract

The invention relates to a motor excitation loss fault detection method and device, a vehicle, a medium and a program product. The method comprises the steps of determining a plurality of first electrical angles in an electrical period of a current operation condition of a to-be-tested motor; for each first electrical angle, determining the first electrical angle as a rotor initial angle of the to-be-tested motor, executing a short-circuit operation to enable a winding of the to-be-tested motor to be in a short-circuit state, and obtaining a winding current final value corresponding to the rotor initial angle; and according to the winding current final value corresponding to each rotor initial angle, determining whether the to-be-tested motor has an excitation loss fault. Thus, the purpose of motor field loss fault detection can be achieved without arranging any additional sensor and directly measuring the back electromotive force information of the winding of the motor to be detected, the motor field loss fault detection operation is simplified, and the motor field loss fault detection efficiency is improved. In addition, the method can be applied to an integer slot pole ratio motor and a fractional slot pole ratio motor, and the applicability of motor field loss fault detection is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of equipment control technology, and in particular to a method, device, vehicle, medium and program product for detecting a motor demagnetization fault. Background Art

[0002] The permanent magnets in the rotor of a permanent magnet motor are important media for converting magnetic energy into kinetic energy. Permanent magnet materials have extremely high magnetic energy product and coercive force, and their rotor magnetic field can achieve higher magnetic induction intensity and higher power density than induction motors. However, permanent magnets are relatively fragile motor components. Under excessive external magnetic fields or excessively high rotor temperatures, demagnetization or even permanent demagnetization failures may occur. For example, under the impact of a magnetic field caused by a transient overcurrent, the eddy currents generated inside the magnet will quickly accumulate heat, which may cause partial demagnetization of the magnet or partial magnet breakage and fall off. From a protection perspective, the electromagnetic and mechanical properties of permanent magnet motors are more susceptible to the external environment. Considering the cost of permanent magnet materials, the cost of a permanent magnet motor is much higher than that of an induction motor. That is to say, permanent magnet motors face higher failure costs at a higher risk of failure. Therefore, it is necessary to monitor the real-time status of the permanent magnet motor rotor so as to timely evaluate the health status of the magnet according to the demagnetization of the rotor and maintain the safe and stable operation of the system. Summary of the invention

[0003] In order to overcome the problems existing in the related art, the present disclosure provides a method, device, vehicle, medium and program product for detecting a motor demagnetization fault.

[0004] According to a first aspect of an embodiment of the present disclosure, a method for detecting a motor demagnetization fault is provided, comprising:

[0005] Determining a plurality of first electrical angles within an electrical cycle of a current operating condition of the motor to be tested;

[0006] For each of the first electrical angles, the first electrical angle is determined as the initial rotor angle of the motor to be tested, and a short-circuit operation is performed to put the winding of the motor to be tested in a short-circuit state, and a final winding current value corresponding to the initial rotor angle is obtained, and the final winding current value is the winding current of the target winding when the short-circuit operation is terminated;

[0007] Whether a demagnetization fault occurs in the motor to be tested is determined according to the final value of the winding current corresponding to each of the initial angles of the rotor.

[0008] According to a second aspect of an embodiment of the present disclosure, a device for detecting a motor demagnetization fault is provided, comprising:

[0009] A first determination module is configured to determine a plurality of first electrical angles within an electrical cycle of a current operating condition of the motor to be tested;

[0010] a first acquisition module, configured to determine the first electrical angle as the rotor initial angle of the short-circuit operation of the motor to be tested for each of the first electrical angles, perform a short-circuit operation to put the winding of the motor to be tested in a short-circuit state, and obtain a winding current final value corresponding to the rotor initial angle, wherein the winding current final value is the winding current of the target winding when the short-circuit operation is terminated;

[0011] The second determination module is configured to determine whether the motor to be tested has a demagnetization fault according to a final value of the winding current corresponding to each of the initial angles of the rotor.

[0012] According to a third aspect of an embodiment of the present disclosure, there is provided an electronic device, including:

[0013] processor;

[0014] a memory for storing processor-executable instructions;

[0015] The processor is configured to execute the instructions to implement the steps of the method for detecting motor demagnetization fault described in the first aspect of the embodiment of the present disclosure.

[0016] According to a fourth aspect of an embodiment of the present disclosure, a computer-readable storage medium is provided, on which computer program instructions are stored. When the program instructions are executed by a processor, the steps of the method for detecting motor demagnetization fault described in the first aspect of the embodiment of the present disclosure are implemented.

[0017] According to a fifth aspect of an embodiment of the present disclosure, a computer program product is provided, comprising a computer program, which, when executed by a processor, implements the steps of the method for detecting motor demagnetization fault described in the first aspect of an embodiment of the present disclosure.

[0018] By adopting the above technical solution, first, multiple first electrical angles are determined within the electrical cycle of the current operating condition of the motor to be tested. Then, for each first electrical angle, the first electrical angle is determined as the rotor initial angle of the short-circuit operation of the motor to be tested, and the short-circuit operation is performed to obtain the final value of the winding current corresponding to the rotor initial angle, and then the final value of the winding current corresponding to different rotor initial angles under the short-circuit state can be obtained. Finally, according to the final value of the winding current corresponding to different rotor initial angles, it is determined whether the motor to be tested has a demagnetization fault. In this way, the purpose of detecting the motor demagnetization fault can be achieved without equipping any additional sensors or directly measuring the winding back electromotive force information of the motor to be tested, which simplifies the motor demagnetization fault detection operation and improves the efficiency of the motor demagnetization fault detection. In addition, the method can be applied to integer slot-pole ratio permanent magnet motors and fractional slot-pole ratio permanent magnet motors, which improves the applicability of motor demagnetization fault detection.

[0019] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0021] Figure 1 It is a schematic diagram of an application scenario of a method for detecting a motor demagnetization fault according to an exemplary embodiment.

[0022] Figure 2 The figure is a flow chart of a method for detecting a motor demagnetization fault according to an exemplary embodiment.

[0023] Figure 3A is a schematic diagram of an electric drive system when a winding is in a short-circuit state according to an exemplary embodiment.

[0024] Figure 3B According to an exemplary embodiment, Figure 3A The equivalent circuit diagram of the electric drive system shown.

[0025] Figure 4 is a schematic diagram showing a winding current and a final value of the winding current in a short-circuit response according to an exemplary embodiment.

[0026] Figure 5 is a waveform diagram of a phase a winding current according to an exemplary embodiment.

[0027] Fig. 6A is a schematic diagram showing an electric drive system in which a switch tube is in an off state according to an exemplary embodiment.

[0028] Figure 6B is an equivalent circuit diagram showing an electric drive system in the first stage according to an exemplary embodiment.

[0029] Figure 6C is an equivalent circuit diagram of a second-stage electric drive system according to an exemplary embodiment.

[0030] Figure 7 is a waveform of a winding current and a final value of the winding current according to an exemplary embodiment.

[0031] Figure 8 is another waveform diagram of the a-phase winding current according to an exemplary embodiment.

[0032] Fig. 9 is a schematic diagram showing a back-electromotive force estimation result and a back-electromotive force measurement result according to an exemplary embodiment.

[0033] Fig.10 The figure is a block diagram of a device for detecting a motor demagnetization fault according to an exemplary embodiment.

[0034] Fig.11 is a block diagram of a vehicle according to an exemplary embodiment. DETAILED DESCRIPTION

[0035] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0036] It should be noted that all actions of acquiring signals, information or data in the present disclosure are carried out in compliance with the relevant data protection laws and policies of the country where the device is located and with the authorization given by the owner of the corresponding device.

[0037] The root cause of the influence of partial rotor demagnetization on motor performance is that its asymmetric magnetic flux distribution causes the distortion of the winding back electromotive force. Generally speaking, asymmetric rotor faults will excite fractional harmonics in the back electromotive force, thereby causing harmonic distortion of torque and speed. In related technologies, the detection of motor demagnetization faults can be mainly divided into the following three methods: (1) Current signal characteristic analysis method. Fractional harmonics are the embodiment of the non-uniform magnetic flux state of the magnet. Therefore, for the detection of partial rotor demagnetization, the harmonic analysis method has been the most widely studied. The slot-pole matching characteristics of the motor determine whether fractional harmonics appear. The fractional harmonics of the integer slot-pole ratio motor will be offset due to the symmetry of the winding. That is, the current signal characteristic analysis method cannot be used to detect motor demagnetization faults for integer slot-pole ratio motors. In addition, when using the current signal characteristic analysis method for detection, it is necessary to add hardware equipment or change the motor structure. Adding hardware equipment or changing the motor structure is not feasible in some applications. Therefore, the accuracy and usability of this method are limited.

[0038] (2) Zero-sequence signal analysis method. The zero-sequence signal is the three-phase common mode parameter. Detecting demagnetization fault based on the zero-sequence signal can eliminate the influence of the three-phase current related items, thereby directly analyzing the magnetic characteristics. For example, the zero-sequence component of the faulty motor can be extracted based on the zero-sequence voltage monitoring method. In fact, the characteristics of the zero-sequence voltage reflect the characteristics of the common-mode back electromotive force of the magnet, and the common-mode back electromotive force of the motor with demagnetization fault will be greatly different from that of the healthy motor in amplitude and spectrum. Therefore, the zero-sequence voltage directly reflects the state of the magnet, and the zero-sequence voltage can be used as a monitoring indicator for partial demagnetization. However, since the zero-sequence voltage amplitude of a healthy motor is affected by factors such as temperature, it is unreliable to detect motor demagnetization fault based on the zero-sequence voltage amplitude. Since the zero-sequence voltage value is extremely small compared to the baseband signal, it is not easy to collect, and when collecting the zero-sequence voltage, it needs to be collected from the neutral point of the motor winding, and the neutral point is inside the motor, so the neutral point needs to be additionally drawn out, which is not available in conventional motors.

[0039] (3) Back-electromotive force analysis method. Back-electromotive force is a characteristic quantity that directly reflects the performance of the magnet. By studying the magnetic field state in the permanent magnet motor in detail and extracting the key characteristics of the back-electromotive force, the demagnetization fault of the permanent magnet motor can be described. For example, a pulsating magnetic field can be injected into the motor at different rotor angle positions through an inverter, and the current characteristics can be observed to detect local or uniform permanent magnet demagnetization faults when the motor is not rotating. For another example, the permanent magnet flux and the armature winding flux vector sum are monitored for each tooth slot of the armature through a search coil, and a variety of asymmetric faults are tested. Alternatively, the back-electromotive force is directly monitored to study the characteristics of the motor back-electromotive force under different demagnetization degrees. In this way, the method based on simulation analysis can reversely analyze the back-electromotive force characteristics of permanent magnet motors with different fault characteristics, and make a preliminary analysis of the fault degree based on the current harmonic situation. However, in conventional fault scenarios, the fault characteristics are unknown, and the degree of magnet fault cannot be accurately obtained based on the analysis of the current and other frequency spectrum characteristic values.

[0040] Considering that for permanent magnet motors, their rotor structures are not equipped with excitation windings and damping windings, and the conductivity of the magnet itself is much smaller than that of copper. Therefore, the rotor of the permanent magnet motor does not have the conditions to form a loop. In this state, the sudden change of the stator flux cannot induce a current response on the rotor, nor can it form an equivalent loop in which the stator winding and the rotor loop are coupled, which will not make the reactance of the non-periodic component in the initial stage of the short-circuit response much smaller than the steady-state synchronous reactance. Therefore, the three-phase short-circuit transient process of the permanent magnet motor will not have excessive current values, so the response current under the short-circuit state has the value of state monitoring.

[0041] In view of this, the present disclosure provides a method, device, vehicle, medium and program product for detecting a motor demagnetization fault, which obtains the final value of the winding current corresponding to different rotor initial angles under a short-circuit state, and determines whether a demagnetization fault occurs in the motor to be tested based on the final value of the winding current corresponding to different rotor initial angles. In this way, the purpose of detecting a motor demagnetization fault can be achieved without equipping any additional sensors or directly measuring the winding back electromotive force information of the motor to be tested, which simplifies the motor demagnetization fault detection operation and improves the efficiency of the motor demagnetization fault detection. In addition, the method can be applied to integer pole ratio permanent magnet motors and fractional slot pole ratio permanent magnet motors, which increases the scope of application of motor demagnetization fault detection.

[0042] Figure 1 FIG. 1 is a schematic diagram showing an application scenario of a method for detecting a motor demagnetization fault according to an exemplary embodiment. Figure 1 As shown, the electric control system includes a bus power supply Vdc, a motor to be tested and an inverter connected in sequence. The midpoints of the three bridge arms included in the inverter are respectively connected to the three-phase windings of the motor to be tested in a one-to-one correspondence. The upper bridge arm and the lower bridge arm of each bridge arm respectively include a set of parallel switch tubes and diodes. For example, in Figure 1 In the embodiment, the upper bridge arm of the first bridge arm includes a switch tube S1 and a diode D1 connected in parallel, the lower bridge arm includes a switch tube S2 and a diode D2 connected in parallel, the upper bridge arm of the second bridge arm includes a switch tube S3 and a diode D3 connected in parallel, the lower bridge arm includes a switch tube S4 and a diode D4 connected in parallel, the upper bridge arm of the third bridge arm includes a switch tube S5 and a diode D5 connected in parallel, and the lower bridge arm includes a switch tube S6 and a diode D6 connected in parallel.

[0043] exist Figure 1 In the figure, the midpoint of the first bridge arm is connected to the endpoint Ea of the a-phase winding, and the voltage at the endpoint Ea is recorded as Va. The midpoint of the second bridge arm is connected to the endpoint Eb of the b-phase winding, and the voltage at the endpoint Eb is recorded as Vb. The midpoint of the third bridge arm is connected to the endpoint Ec of the c-phase winding, and the voltage at the endpoint Ec is recorded as Vc.

[0044] During the control process of the electric drive system, the status of the motor body and the inverter used to control the motor can be dynamically obtained, so as to dynamically adjust the switching frequency of the inverter's switch tube, the inverter's current limit and the motor winding's current limit according to the overall performance of the electric drive system, which together constitute the operating constraints of the electric drive system, thereby ensuring that the electric drive system can operate healthily and stably.

[0045] Figure 2 FIG. 1 is a flow chart showing a method for detecting a motor demagnetization fault according to an exemplary embodiment. Figure 2 As shown, the method for detecting motor demagnetization fault may include the following steps.

[0046] In step S21, a plurality of first electrical angles are determined within an electrical cycle of a current operating condition of the motor to be tested.

[0047] Among them, in the motor, the electrical cycle refers to a complete cycle of stator current change, that is, 0-360 degrees of electrical angle, which is called an electrical cycle. For the motor, an electrical cycle can correspond to a certain angle of physical rotation of the motor rotor, which may be 360 ​​degrees, 180 degrees, 90 degrees or 60 degrees, etc., depending on the arrangement of the motor windings, the number of magnetic pole pairs and the operating conditions of the motor.

[0048] In the present disclosure, multiple first electrical angles can be randomly determined in an electrical cycle. For example, the electrical cycle can be 2π, and the multiple first electrical angles can be any value in 2π. Among them, within multiple first electrical cycles, the difference between any two adjacent first electrical angles can be the same or different, and the present disclosure does not make specific limitations on this.

[0049] In one embodiment, determining multiple first electrical angles within the electrical cycle of the current operating condition of the motor to be measured may include: dividing the electrical cycle of the current operating condition of the motor to be measured to obtain multiple electrical angle regions, determining the starting electrical angle of each electrical angle region as the first electrical angle, and obtaining multiple first electrical angles.

[0050] For example, the electrical cycle of the current operating condition of the motor to be tested can be divided according to fixed intervals to obtain multiple electrical cycle regions. For example, assuming that the electrical cycle of the current operating condition of the motor to be tested is 2π, and the fixed interval is 0.1π, the electrical angle can be divided into 20 regions, that is, 20 electrical angle regions are obtained, and the interval of the starting electrical angle of each electrical angle region is 0.1π. Afterwards, the starting electrical angle of each electrical angle region is determined as the first electrical angle, and 20 first electrical angles are obtained. Among them, the 20 first electrical angles include 0.1π, 0.2π, 0.3π, 0.4π, ..., 2π.

[0051] In step S22, for each first electrical angle, the first electrical angle is determined as the rotor initial angle of the short-circuit operation of the motor to be tested, and the short-circuit operation is performed to put the winding of the motor to be tested in a short-circuit state, and the final value of the winding current corresponding to the rotor initial angle is obtained.

[0052] The final value of the winding current is the winding current of the target winding when the short-circuit operation is terminated. The winding of the motor to be tested is in a short-circuit state, which means that the endpoints of the three-phase winding of the motor to be tested are connected.

[0053] For example, Figure 3A FIG. 1 is a schematic diagram of an electric drive system when a winding is in a short-circuit state according to an exemplary embodiment. Figure 3AAs shown, each end point of the three-phase winding of the motor M to be tested is connected to the negative pole of the bus power supply. For example, the end point Ea of the a-phase winding is connected to the negative pole of the bus power supply via the switch tube S2, the end point Eb of the b-phase winding is connected to the negative pole of the bus power supply via the switch tube S4, and the end point Ec of the c-phase winding is connected to the negative pole of the bus power supply via the switch tube S6.

[0054] Figure 3B According to an exemplary embodiment, Figure 3A The equivalent circuit diagram of the electric drive system is shown in Figure 1. Figure 3B As shown, each phase winding of the motor to be tested can be equivalent to an inductor, a resistor and an equivalent voltage source of back electromotive force connected in series. For example, the b-phase winding can be equivalent to an inductor L connected in series. s_b , resistor R s_b And the back electromotive force equivalent voltage source Ub_bemf.

[0055] In the present disclosure, for each first electrical angle, first, the first electrical angle is determined as the initial rotor angle of the motor to be tested, then a short-circuit operation is performed to put the winding of the motor to be tested in a short-circuit state, and finally, the final value of the winding current corresponding to the initial rotor angle is obtained.

[0056] In one possible manner, the winding current value can be collected in real time at the start of the short-circuit operation, and the current value is the current value of the short-circuit response, and the winding current value collected at the end of the short-circuit operation is determined as the final value of the winding current corresponding to the initial angle of the rotor.

[0057] In another possible manner, the winding current value may be collected only once at the end of the short-circuit operation, and the winding current value may be determined as the final value of the winding current corresponding to the initial angle of the rotor.

[0058] In the present disclosure, for each rotor initial angle, the duration of the winding being in the short-circuit state may be the same.

[0059] First of all, it should be understood that, considering that the magnitude of the current value on each phase winding is the same, there is only a difference in phase, therefore, in the present disclosure, the winding current value can be the current value collected on any winding in the motor to be tested, that is, the target winding can be any phase winding in the three-phase winding. In addition, the final value of the winding current can be collected by a current collection device set on the winding in the prior art, which will not be described in detail in the present disclosure.

[0060] Secondly, it should be understood that performing the short-circuit operation does not affect the normal rotation of the motor, that is, when the winding of the motor to be tested is in a short-circuit state, the rotor of the motor to be tested rotates normally from the initial angle of the rotor.

[0061] In step S23, it is determined whether a demagnetization fault occurs in the motor to be tested according to the final value of the winding current corresponding to each initial rotor angle.

[0062] Since the back electromotive force, an indicator for detecting motor demagnetization fault, can be called induced electromotive force, and the induced electromotive force changes with the final value of the winding current, it is possible to determine whether the motor to be tested has a demagnetization fault based on the final value of the winding current corresponding to different initial rotor angles.

[0063] By adopting the above technical solution, first, multiple first electrical angles are determined within the electrical cycle of the current operating condition of the motor to be tested. Then, for each first electrical angle, the first electrical angle is determined as the rotor initial angle of the short-circuit operation of the motor to be tested, and the short-circuit operation is performed to obtain the final value of the winding current corresponding to the rotor initial angle, and then the final value of the winding current corresponding to different rotor initial angles under the short-circuit state can be obtained. Finally, according to the final value of the winding current corresponding to different rotor initial angles, it is determined whether the motor to be tested has a demagnetization fault. In this way, the purpose of detecting the motor demagnetization fault can be achieved without equipping any additional sensors or directly measuring the winding back electromotive force information of the motor to be tested, which simplifies the motor demagnetization fault detection operation and improves the efficiency of the motor demagnetization fault detection. In addition, the method can be applied to integer slot-pole ratio permanent magnet motors and fractional slot-pole ratio permanent magnet motors, which improves the applicability of motor demagnetization fault detection.

[0064] In the present disclosure, step S23 determines whether a demagnetization fault occurs in the motor to be tested based on the final value of the winding current corresponding to each rotor initial angle, and may include: determining the winding back electromotive force information of the motor to be tested within the electrical cycle based on the final value of the winding current corresponding to each rotor initial angle; determining whether a demagnetization fault occurs in the motor to be tested based on the winding back electromotive force information of the motor to be tested.

[0065] As described above, the winding back electromotive force can be called the winding induced voltage, and the winding induced voltage is related to the winding current. Therefore, in the present disclosure, the winding back electromotive force information of the motor to be tested within the electrical cycle can be determined based on the final value of the winding current corresponding to each initial angle of the rotor, and then the demagnetization fault of the motor to be tested can be determined based on the winding back electromotive force information of the motor to be tested.

[0066] In this embodiment, considering that the winding back electromotive force can directly reflect the performance of the magnet, it is possible to further determine the winding back electromotive force information of the motor to be tested within the electrical cycle based on the final value of the winding current corresponding to each initial angle of the rotor, and then determine whether the motor to be tested has a demagnetization fault based on the winding back electromotive force information.

[0067] For example, if the winding back electromotive force information indicates that the winding back electromotive force has a non-sinusoidal characteristic, it is determined that a demagnetization fault occurs in the motor to be tested; otherwise, it is determined that a demagnetization fault does not occur in the motor to be tested.

[0068] By adopting the above technical solution, considering that the winding back electromotive force can directly reflect the performance of the magnet, after obtaining the final value of the winding current corresponding to each rotor initial angle, the winding back electromotive force information of the motor to be tested within the electrical cycle can be further determined according to the final value of the winding current corresponding to each rotor initial angle, and then based on the winding back electromotive force information, whether the motor to be tested has a demagnetization fault can be detected. In this way, the reliability of the motor demagnetization fault detection is improved.

[0069] In one embodiment, since the changing trend of the final value of the winding current with the initial angle of the rotor is the same as the changing trend of the back electromotive force with the initial angle of the rotor, there is only a phase deviation. Therefore, the changing trend of the final value of the winding current with the initial angle of the rotor can be determined according to the final value of the winding current corresponding to each initial angle of the rotor, and then the changing trend of the back electromotive force with the initial angle of the rotor can be determined. Therefore, in this embodiment, the winding back electromotive force information may include the changing trend of the winding back electromotive force. According to the final value of the winding current corresponding to each initial angle of the rotor, the winding back electromotive force information of the motor to be measured within the electrical cycle is determined, which may include: according to the final value of the winding current corresponding to each initial angle of the rotor, the changing trend of the final value of the winding current with the initial angle of the rotor within the electrical cycle is determined, and the changing trend is determined as the changing trend of the winding back electromotive force of the motor to be measured.

[0070] For example, according to Figure 2 After obtaining the final value of the winding current corresponding to each rotor initial angle in step S22, the final value of the winding current corresponding to each rotor initial angle can be plotted on the same graph, the horizontal axis of which is the rotor initial angle, to obtain the variation trend of the final value of the winding current with the rotor initial angle within the electrical cycle.

[0071] Figure 4 FIG. 1 is a schematic diagram showing a winding current and a final value of the winding current in a short-circuit response according to an exemplary embodiment. Figure 4 As shown in the left figure in , the winding current curves corresponding to different rotor initial angles can be plotted in the same coordinate system. For example, curve ① represents the winding current curve corresponding to the rotor initial angle 2π / N, curve ② represents the winding current curve corresponding to the rotor initial angle 4π / N, ..., curve N represents the winding current curve corresponding to the rotor initial angle 2π.

[0072] like Figure 4 As shown in the right figure in , the final value of the winding current corresponding to each initial rotor angle is plotted on a coordinate system with the same horizontal axis as the initial rotor angle to obtain a curve of the final value of the winding current changing with the initial rotor angle.

[0073] Since the curve of the final value of the winding current changing with the initial rotor angle and the curve of the winding back electromotive force changing with the initial rotor angle have the same changing trend but a phase difference, the changing trend of the final value of the winding current changing with the initial rotor angle is the changing trend of the winding back electromotive force.

[0074] Accordingly, determining whether a demagnetization fault occurs in the motor to be tested based on the winding back electromotive force information of the motor to be tested may include: if the variation trend of the winding back electromotive force does not present a sinusoidal variation trend, determining that a demagnetization fault occurs in the motor to be tested.

[0075] For example, if the variation trend of the winding back electromotive force presents a sinusoidal variation trend, it is determined that the motor to be tested has not suffered a demagnetization fault, and if the variation trend of the winding back electromotive force does not present a sinusoidal variation trend, it is determined that the motor to be tested has suffered a demagnetization fault.

[0076] By adopting the above technical solution, the changing trend of the final value of the winding current with the change of the initial angle of the rotor is determined as the changing trend of the winding back electromotive force of the motor to be tested, and whether the motor to be tested has a demagnetization fault is detected according to whether the changing trend of the winding back electromotive force presents a sinusoidal changing trend, which simplifies the motor demagnetization fault detection operation and improves the efficiency of the motor demagnetization fault detection. In addition, since both the integer slot pole ratio permanent magnet motor and the fractional slot pole ratio permanent magnet motor can obtain the final value of the winding current corresponding to each rotor initial angle, and then the changing trend of the winding back electromotive force can be determined for the integer slot pole ratio permanent magnet motor and the fractional slot pole ratio permanent magnet motor, and then it can be detected whether the motor has a demagnetization fault, therefore, the method can be applied to the integer slot pole ratio permanent magnet motor and the fractional slot pole ratio permanent magnet motor, and the applicability of the motor demagnetization fault detection is improved.

[0077] Due to the existence of the motor impedance angle, there will be a phase difference between the waveform of the final value of the winding current obtained based on the short-circuit operation as the rotor initial angle changes and the waveform of the winding back electromotive force as the rotor initial angle changes. But in fact, the angle deviation caused by the impedance angle does not affect the characterization of the waveform of the winding back electromotive force as the rotor initial angle changes. Theoretically, when the circuit response reaches a steady state, the phase difference between the voltage and current in the loop will be completely related to the impedance angle. However, during the transient response process, due to the characteristic that the winding magnetic flux cannot change suddenly, the non-periodic component of the current will be excited. In the initial stage of the response, the non-periodic component It will not decay sufficiently in a short time, so the non-periodic component will greatly affect the initial characteristics of the current transient response. When the final value of the winding current is analyzed with the initial position of the rotor as a variable, the expression of the winding current response characteristic equation can be converted from formula (1) to formula (2):

[0078]

[0079] in, U an represents the amplitude of the back electromotive force, w represents the speed of the motor to be tested, and R s and L s are the equivalent resistance and equivalent inductance of the motor winding to be tested. For example, R s and L s They can be the equivalent resistance and equivalent inductance of the target winding, or the total equivalent resistance and total equivalent inductance of the multi-phase windings connected in series. α represents the initial rotor angle of the motor to be tested. Characterizes the impedance angle of the motor under test, and t represents time, i a Characterizes the winding current value.

[0080] For example, if the motor to be tested is a surface-mounted permanent magnet synchronous motor, the equivalent resistance of each phase winding is the same, and the equivalent inductance of each phase winding is the same.

[0081] It should be understood that the equivalent resistance R of the motor winding to be tested s The equivalent resistance of each phase winding may be included, for example, the equivalent resistance R s The equivalent resistance R of the a-phase winding can be s_a , the equivalent resistance R of phase b winding s_b and the equivalent resistance R of the c-phase winding s_c Similarly, the equivalent inductance L s The equivalent inductance L of the a-phase winding can be included s_a , equivalent inductance L of phase b winding s_b and the equivalent inductance L of the c-phase winding s_c At least one of the following. Wherein, for each phase winding, a current response characteristic equation of the phase winding is calculated according to the equivalent resistance and equivalent inductance of the phase winding.

[0082] According to formula (2), compared with the initial value U of the back electromotive force that causes a short circuit response in the exciting winding circuit, an sin(α), the phase angle difference between the winding current that excites the winding circuit to respond to a short circuit and its Among them, ρ is related to the duration of the short-circuit operation. Selecting different durations of short-circuit operation will affect the amplitude and angle offset of the waveform of the final value of the winding current changing with the initial angle of the rotor, but the overall change trend characteristics will not be affected. Therefore, when the duration of the short-circuit operation is fixed, the winding current is only related to the amplitude of the back electromotive force and the equivalent parameters of the motor to be measured. In order to further obtain the complete waveform or function equation of the back electromotive force changing with the initial angle of the rotor, in addition to determining the change trend of the back electromotive force, it is also necessary to determine the amplitude of the back electromotive force. Among them, the amplitude of the back electromotive force refers to the maximum value of the back electromotive force.

[0083] In the present disclosure, since the winding back electromotive force is not easy to measure, but the voltage of the bus power supply is measurable, the amplitude of the back electromotive force can be inferred from the bus power supply. In other words, the amplitude of the back electromotive force is inferred based on the relationship between the voltage of the bus power supply and the amplitude of the winding back electromotive force and the known voltage of the bus power supply.

[0084] From the above content, it can be seen that when the speed of the motor to be tested is high, tends to positive infinity, that is, the impedance angle As the rotor's initial angle α approaches but does not reach 180°, the sine term will reach a peak before starting to decay, and the decay term The difference between the two will reach the peak value first and then begin to decrease. The short-circuit response winding current, which is the difference between the two items, has a waveform change trend as shown below: Figure 5 As shown in Figure 1, the current of phase a winding starts from zero and reaches the peak value first, then decreases to zero. When the winding current reaches zero again, the zero crossing point will satisfy Therefore, when determining the magnitude of the back electromotive force, the first electrical angle determined in step S21 includes at least one electrical angle whose value satisfies For the convenience of description, the initial angle of the rotor when crossing the zero point is recorded as the second electrical angle α0.

[0085] In one embodiment, in step S21, determining a plurality of first electrical angles within the electrical cycle of the current operating condition of the motor to be tested may include: estimating the motor impedance angle according to the rotation speed of the motor to be tested The value of and the angle ρ, where ω represents the speed of the motor to be tested, t represents the time, Characterize the equivalent parameters of the motor to be tested; The difference between the value of and the angle ρ is determined as the second electrical angle; within the electrical cycle of the motor to be measured, multiple first electrical angles are determined, and there is at least one second electrical angle α0 among the multiple first electrical angles.

[0086] Since the speed ω of the motor to be tested is relatively large, according to the formula Estimated motor impedance angle The value of is close to 90°, and the value of angle ρ is close to -90°. The difference between the value of and the angle ρ is determined as the second electrical angle, that is, the second electrical angle is close to but not equal to 180°. For example, the second electrical angle α0 can be a value slightly less than 180°. For example, the second electrical angle α0 can be 178°, 179°, etc. Among the determined multiple first electrical angles, there is at least one second electrical angle α0.

[0087] In one embodiment, the detection method provided by the present disclosure is applied to an electric drive system, which includes a bus power supply, the motor to be tested, and an inverter connected in sequence, wherein the midpoints of the three-phase bridge arms included in the inverter are connected one-to-one with the three-phase windings included in the motor to be tested, and the upper bridge arm and the lower bridge arm of each bridge arm respectively include a group of parallel switch tubes and diodes. The circuit diagram of the electric drive system is shown in FIG. Figure 1 or Figure 3A shown.

[0088] The winding back electromotive force information may include the amplitude of the winding back electromotive force. Accordingly, the winding back electromotive force information of the motor to be tested within the electrical cycle is determined according to the final value of the winding current corresponding to each initial angle of the rotor. It may also include: for the second electrical angle, when the short-circuit operation is terminated, each switch tube in the three-phase bridge arm is controlled to be in a disconnected state so that the three-phase winding forms a loop with the bus power supply through the diodes in the three-phase bridge arm; the amplitude of the winding back electromotive force is determined according to the current response function of the winding in the loop and the equivalent parameters of the motor to be tested in the loop.

[0089] In this embodiment, when the second electrical angle is the initial angle of the rotor, a short-circuit operation is performed so that the winding and the bus power supply are in an isolated state (eg Figure 3B As shown), the short-circuit response current is rapidly generated inside the winding. When the expected short-circuit duration is reached, that is, when the short-circuit operation duration is reached, the switches in the three-phase bridge arm are controlled to be disconnected, and the current that loses the original flow path will continue to flow through the diode in the bridge arm. Its mode is close to the reverse charging process of the bus capacitor in the prior art, and the current flows from the winding into the bus power supply according to the original flow direction.

[0090] Fig. 6A FIG. 1 is a schematic diagram showing an electric drive system in which a switch tube is in an off state according to an exemplary embodiment. Fig. 6A As shown, the current flows into the winding of the motor M to be tested through the diode D2 in the first bridge arm, and flows from the winding of the motor M to be tested into the bus power supply Vdc through the diode D3 in the second bridge arm and the diode D5 in the third bridge arm.

[0091] exist Fig. 6A In the electric drive system shown in FIG. 1 , there are three stages in which the three-phase current flows to the bus power supply Vdc. The first stage is the simultaneous flow of the three phases (i.e., Fig. 6AAs shown, all three bridge arms have freewheeling current), and the two-phase windings are in parallel. Figure 6B FIG. 1 is an equivalent circuit diagram of an electric drive system in the first stage according to an exemplary embodiment. Figure 6B As shown, in the first stage, the b-phase winding and the c-phase winding are connected in parallel. It should be understood that the present disclosure is not specifically limited to the two-phase windings in parallel.

[0092] like Figure 6B As shown, the current flows from the negative pole of the bus into the a-phase winding of the motor M to be tested, and then flows into the positive pole of the bus through the b-phase winding and the c-phase winding connected in parallel.

[0093] In a first implementation, the magnitude of the winding back electromotive force may be determined according to the current response function of the first stage. For example, according to the current response function of the winding in the loop and the equivalent parameters of the motor to be measured in the loop, the implementation method for determining the magnitude of the winding back electromotive force is:

[0094] First, in the first stage when freewheeling current exists in the three-phase windings, the first current response function of the winding in the first stage is determined according to the final value of the winding current corresponding to the second electrical angle.

[0095] In the first stage, when the three-phase currents are freewheeling through the diodes at the same time, the loop structure formed by the three-phase winding and the bus power supply is complex. The freewheeling characteristics can be analyzed based on the symmetrical three-phase winding loop. For the surface-mounted hidden-pole permanent magnet motor, considering the voltage equations of each three-phase winding loop, we can get:

[0096]

[0097] Among them, V j The loop voltage equation representing the j-phase winding, j ranges from a, b and c, R s_j Characterizes the equivalent resistance of the j-phase winding, i j Characterizes the current of the j-phase winding, L s_j Characterize the equivalent inductance of the j-phase winding, It represents the flux value of the rotor permanent magnet acting on the j-phase winding, and V0 represents the neutral voltage value.

[0098] The negative pole of the bus power supply is taken as the voltage reference point V N , adding the voltage equations of the three-phase windings gives:

[0099]

[0100] in, Characterizes the common mode of the three-phase winding back electromotive force, that is, the zero-sequence voltage component. It is mainly composed of the third harmonic of the back electromotive force. The amplitude is related to the motor structure and is generally within 1% of the back electromotive force fundamental amplitude. Based on the above analysis, it can be seen that the voltage value of the neutral point is determined by the connection between the three-phase winding end and the busbar. V aN 、V bN and V cN They are the negative pole voltages of the a-phase winding, b-phase winding and c-phase winding relative to the bus power supply, and Fig. 6A In the example, the voltages of each winding end to the negative pole of the bus are V aN =0, V bN =V dc , V cN =V dc Compared with the voltage of the bus power supply, the zero-sequence voltage amplitude of the back electromotive force is very small and can be ignored. Therefore, the potential difference V between the neutral point and the negative pole of the bus can be obtained. 0N =(2 / 3)V dc .

[0101] According to the connection between the three-phase end winding and the busbar, the neutral point voltage can be analyzed to obtain the voltage equation of each phase circuit, and then the current response equation can be constructed. Fig. 6A Taking the a-phase winding in the electric drive system shown in as an example, the first current response function equation of the a-phase winding in the freewheeling process can be obtained as shown in formula (5):

[0102]

[0103] Where, I represents the final value of the winding current of phase a. In formula (5), R s1 and L s1 Respectively represent the equivalent resistance and equivalent inductance of phase a winding, that is, R s1 =R s_a , L s1 =L s_a .

[0104] The bus power supply voltage V dc The related terms and back electromotive force U an By moving the related terms to both sides of the equation, we can get the proportional equation of bus voltage and winding back electromotive force:

[0105]

[0106] Next, according to the first current response function and the first equivalent parameter of the motor to be measured, a first relationship between the bus power supply voltage and the amplitude of the winding back electromotive force is determined. The first equivalent parameter is the equivalent parameter of the target winding. For example, if the target winding is a phase winding, the first equivalent parameter can be

[0107] The following describes a method for determining the equivalent parameters of the motor to be tested.

[0108] For example, the method may further include: determining the equivalent parameters of the motor to be tested by the following formula:

[0109]

[0110] Wherein, α0 represents the second electrical angle, t1 represents the duration of each short-circuit operation, and Δθ1 represents the position angle change of the motor to be tested in the short-circuit state.

[0111] As mentioned above, refer to Figure 5 As shown in the winding current waveform, the winding current starts from zero and reaches the peak value first, then decreases to zero. When the current reaches zero again, the zero crossing point will satisfy Right now,

[0112] in,

[0113] Assuming that the duration of the short circuit state is t1, ωt1 = Δθ1, we can get formula (7):

[0114]

[0115] In practical applications, the duration of the short-circuit state is about 100 μs. It can be approximately equivalent to Therefore, formula (7) can be converted into formula (8):

[0116]

[0117] So far, the is a quadratic equation with unknown quantities, and the coefficients of each term are all measurable parameters. Therefore, based on formula (8), Solve it exactly and get When R s =R s1 , L s =L s1 The first equivalent parameter can be obtained when

[0118] The first equivalent parameter of the motor to be tested is obtained in the above manner. Then, according to the first current response function and the first equivalent parameter of the motor to be tested, the first relationship between the bus power supply voltage and the amplitude of the winding back electromotive force is determined. Substituting into formula (6), the first relationship between the bus power supply voltage and the amplitude of the winding back electromotive force is obtained. The expression of the first relationship is shown in the following formula (9):

[0119]

[0120] Among them, U an Characterizes the magnitude of the winding back EMF, V dc represents the voltage value of the bus power supply, Δθ2 represents the position angle change of the motor to be tested in the first stage, Δθ1 represents the position angle change of the motor to be tested in the short-circuit state, t1 represents the duration of each short-circuit operation, t2 represents the duration of the first stage, α0 represents the second electrical angle, Characterize the first equivalent parameter of the motor to be tested, R s1 Characterizes the equivalent resistance of the target winding, L s1 Characterize the equivalent inductance of the target winding.

[0121] Afterwards, the first amplitude of the winding back electromotive force is determined according to the bus power supply voltage and the above first relationship. For example, the bus power supply voltage is substituted into formula (9) to obtain the first amplitude of the winding back electromotive force.

[0122] Finally, the first amplitude is determined as the amplitude of the winding back electromotive force.

[0123] In a second implementation, the magnitude of the winding back electromotive force can be determined according to the current response function of the second stage. For example, according to the current response function of the winding in the loop and the equivalent parameters of the motor to be measured in the loop, the implementation method for determining the magnitude of the winding back electromotive force is:

[0124] First, in the second stage when the freewheeling current exists in the two-phase windings, the second current response function of the windings in the second stage is determined according to the final value of the winding current corresponding to the second electrical angle.

[0125] After the first stage, the second stage begins. In the second stage, the current of one phase of the two-phase winding in parallel returns to zero and exits the loop. At this time, although the loop voltage equation of the remaining two-phase winding still satisfies formula (3), the terminal voltage of the phase winding that exits will no longer be determined by the voltage of the bus power supply, so the loop structure characteristics of the three-phase winding will change. Assuming that the c-phase winding exits the loop, the a-phase winding and the b-phase winding that are still in the freewheeling state are connected to the positive and negative poles of the bus power supply respectively, then the loop voltage equations of the a-phase winding and the b-phase winding are added to obtain formula (10):

[0126]

[0127] It can be seen that the voltage characteristics of the neutral point are affected by the bus voltage value and the back electromotive force of the c-phase winding. This makes the analysis method of the single-phase circuit more complicated. In fact, when the freewheeling of a phase winding ends and exits the circuit, and only two phases are in a continuous flow state, the two phase windings will jointly form a complete freewheeling path. Therefore, a two-phase series circuit can be selected for analysis. For example, Figure 6C FIG. 1 is an equivalent circuit diagram of a second-stage electric drive system according to an exemplary embodiment. Figure 6C As shown, the current of the c-phase winding returns to zero and exits the loop, and the a-phase winding and the b-phase winding form a series loop.

[0128] exist Figure 6C In the equation, the second current response function equation of the two-phase winding is as shown in formula (11):

[0129]

[0130] In the above formula 11, m represents the ratio of the winding current at the end of the first stage to the final value of the winding current corresponding to the second electrical angle, Characterize the second equivalent parameter of the motor under test. Figure 6C In, R s2 =R s_b , L s2 =L s_b .

[0131] The second equivalent parameter can be determined by referring to the above formulas (7) and (8). For example, R in the above formulas (7) and (8) s =R s1 +R s2 , L s =L s1 +L s2 , we can get the second equivalent parameter Among them, R s1 +R s2 Characterization Figure 6C The total equivalent resistance in the series circuit, L s1 +L s2 Characterization Figure 6C The total equivalent inductance in the series circuit in .

[0132] The second equivalent parameter of the motor to be tested is obtained in the above manner. Then, the second relationship between the bus power supply voltage and the amplitude of the winding back electromotive force is determined according to the second current response function and the second equivalent parameter of the motor to be tested. Substituting into formula (11), the second relationship between the bus power supply voltage and the amplitude of the winding back electromotive force is obtained. The expression of the second relationship is shown in the following formula (12):

[0133]

[0134] Among them, U an Characterizes the magnitude of the winding back EMF, V dc represents the voltage value of the bus power supply, α0 represents the second electrical angle, Δθ1 represents the position angle change of the motor to be tested in the short-circuit state, t1 represents the duration of each short-circuit operation, t3 represents the duration of the second stage, m represents the ratio of the winding current at the end of the first stage to the final value of the winding current corresponding to the second electrical angle, is the second equivalent parameter of the motor to be tested, R s1 +R s2 The sum of the equivalent resistances of the two-phase windings with freewheeling current, L s1 +L s2 Characterizes the sum of the equivalent inductances of the two-phase windings with freewheeling current.

[0135] Then, the second amplitude of the winding back electromotive force is determined according to the bus power supply voltage and the second relationship. For example, the bus power supply voltage is substituted into formula (12) to obtain the first amplitude of the winding back electromotive force.

[0136] Finally, the second amplitude is determined as the amplitude of the winding back electromotive force.

[0137] In a third embodiment, determining the amplitude of the back electromotive force of the winding according to the current response function of the winding in the loop and the equivalent parameters of the motor to be tested in the loop includes:

[0138] In the first stage when the freewheeling current exists in the three-phase windings, a first current response function of the winding in the first stage is determined according to the final value of the winding current corresponding to the second electrical angle;

[0139] Determining a first relationship between a bus power supply voltage and an amplitude of a winding back electromotive force according to the first current response function and a first equivalent parameter of the motor to be measured, wherein the first equivalent parameter is an equivalent parameter of the target winding;

[0140] Determining a first amplitude of a winding back electromotive force according to the bus power supply voltage and the first relationship;

[0141] In the second stage when the freewheeling current exists in the two-phase windings, determining the second current response function of the winding in the second stage according to the final value of the winding current corresponding to the second electrical angle;

[0142] Determine a second relationship between the bus power supply voltage and the amplitude of the winding back electromotive force according to the second current response function and a second equivalent parameter of the motor to be measured, wherein the second equivalent parameter is a total equivalent parameter of the two-phase winding with freewheeling current;

[0143] determining a second amplitude of the winding back electromotive force according to the bus power supply voltage and the second relationship;

[0144] The amplitude of the winding back electromotive force is determined according to the first amplitude and the second amplitude.

[0145] In this embodiment, the first amplitude is determined according to the first embodiment, and the second amplitude is determined according to the second embodiment, and then the amplitude of the winding back electromotive force is determined according to the first amplitude and the second amplitude. For example, the weights of the first amplitude and the second amplitude can be set, and the sum of the product of the first amplitude and the first amplitude weight and the product of the second amplitude and the second amplitude weight is determined as the amplitude of the winding back electromotive force. For example, when the respective weights are 0.5, the average value of the first amplitude and the second amplitude is determined as the amplitude of the winding back electromotive force.

[0146] In an embodiment in which the winding back-EMF information includes a changing trend of the winding back-EMF and an amplitude of the winding back-EMF, a specific implementation method for determining whether a demagnetization fault occurs in the motor to be tested based on the winding back-EMF information of the motor to be tested is as follows: determining a function of the winding back-EMF based on the changing trend of the winding back-EMF and the amplitude of the winding back-EMF; if the function of the winding back-EMF is not a sinusoidal function, it is determined that a demagnetization fault occurs in the motor to be tested.

[0147] In this embodiment, in order to obtain a complete back-electromotive force equation function, in addition to obtaining the changing trend of the winding back-electromotive force, the amplitude of the winding back-electromotive force can be further obtained, and then the function of the winding back-electromotive force can be determined according to the changing trend of the winding back-electromotive force and the amplitude of the winding back-electromotive force, and then whether the motor has a demagnetization fault can be detected according to whether the function of the winding back-electromotive force is a sinusoidal function.

[0148] For example, a five-pole label permanent magnet motor is used as a test prototype. The short-circuit state lasts for 100μs. One electrical cycle is divided into 32 electrical angle regions. The interval of the rotor initial angle in each electrical angle region is π / 16. The short-circuit response results corresponding to different rotor initial angles, that is, the final value of the winding current, are plotted on the same graph with the rotor initial angle as the horizontal coordinate, and the following can be obtained: Figure 7 The test results are shown in Figure 1. Among them, the short-circuit response result represents the change of winding current under short-circuit state, and the waveform fitting result represents the change of winding current final value with the initial angle of the rotor.

[0149] When the initial rotor angle is close to but not yet 180°, after the short-circuit operation is completed, each switch in the control bridge arm is disconnected, so that the current flows through the diode in the original direction. The current response characteristics of the a-phase winding are as follows: Figure 8As shown. Based on the current response at the characteristic position, for example, the initial rotor angle at the second zero crossing, the relevant parameters in the equivalent circuit can be calculated, and then the amplitude of the back electromotive force can be estimated. Based on the change trend of the final value of the winding current with the initial rotor angle, the complete back electromotive force waveform can be obtained, that is, the equation function of the back electromotive force can be obtained.

[0150] Fig. 9 is a schematic diagram showing a back electromotive force estimation result and a back electromotive force measurement result according to an exemplary embodiment. The back electromotive force estimation result refers to the result obtained based on the change area of ​​the final value of the winding current with the change of the initial angle of the rotor and the amplitude of the back electromotive force determined based on the voltage of the bus power supply. Fig. 9 In the embodiment, the back-EMF estimation result matches the back-EMF measurement result, that is to say, the back-EMF characterized based on the provided method matches the actually measured back-EMF. Thus, without any additional sensing equipment, the back-EMF can be accurately characterized based on the method provided in the present invention, thereby ensuring the reliability and accuracy of the motor demagnetization fault detection method provided in the present invention.

[0151] Based on the same inventive concept, the present disclosure also provides a device for detecting a motor demagnetization fault. Fig.10 FIG. 1 is a block diagram of a detection device for a motor demagnetization fault according to an exemplary embodiment. Fig.10 As shown, the motor demagnetization fault detection device 1000 may include:

[0152] A first determination module 1001 is configured to determine a plurality of first electrical angles within an electrical cycle of a current operating condition of the motor to be tested;

[0153] The first acquisition module 1002 is configured to determine the first electrical angle as the rotor initial angle of the short-circuit operation of the motor to be tested for each first electrical angle, perform a short-circuit operation to put the winding of the motor to be tested in a short-circuit state, and obtain a winding current final value corresponding to the rotor initial angle, wherein the winding current final value is the winding current of the target winding when the short-circuit operation is terminated;

[0154] The second determination module 1003 is configured to determine whether the motor to be tested has a demagnetization fault according to a final value of the winding current corresponding to each of the initial angles of the rotor.

[0155] Optionally, the second determining module 1003 may include:

[0156] A first determination submodule is configured to determine the winding back electromotive force information of the motor to be tested within the electrical cycle according to the final value of the winding current corresponding to each of the initial angles of the rotor;

[0157] The second determination submodule is configured to determine whether the motor to be tested has a demagnetization fault according to the winding back electromotive force information of the motor to be tested.

[0158] Optionally, the winding back electromotive force information includes a changing trend of the winding back electromotive force; the first determination submodule is configured to determine the changing trend of the winding current final value with the rotor initial angle during the electrical cycle according to the winding current final value corresponding to each of the rotor initial angles, and determine the changing trend as the changing trend of the winding back electromotive force of the motor to be tested.

[0159] Optionally, the second determination submodule is configured to determine that a demagnetization fault occurs in the motor to be tested if the change trend of the winding back electromotive force does not present a sinusoidal change trend.

[0160] Optionally, the first determining module 1001 may include:

[0161] The estimation submodule is configured to estimate the motor impedance angle according to the speed of the motor to be measured. The value of and the angle ρ, where ω represents the speed of the motor to be tested, t represents the time, Characterizing equivalent parameters of the motor to be tested;

[0162] The third determination submodule is configured to calculate the estimated resistance impedance angle The difference between the value of and the angle ρ is determined as the second electrical angle;

[0163] The fourth determination submodule is configured to determine a plurality of first electrical angles within an electrical cycle of the motor to be measured, wherein there is at least one second electrical angle among the plurality of first electrical angles.

[0164] Optionally, the winding back electromotive force information includes the amplitude of the winding back electromotive force; the detection method is applied to an electric drive system, the electric drive system includes a bus power supply, the motor to be tested and an inverter connected in sequence, the midpoints of the three-phase bridge arms included in the inverter are connected one-to-one with the three-phase winding included in the motor to be tested, and the upper bridge arm and the lower bridge arm of each bridge arm respectively include a group of parallel switching tubes and diodes; the first determination submodule is configured as: for the second electrical angle, when the short-circuit operation is terminated, each switching tube in the three-phase bridge arm is controlled to be in a disconnected state, so that the three-phase winding forms a loop with the bus power supply through the diode in the three-phase bridge arm; the amplitude of the winding back electromotive force is determined according to the current response function of the winding in the loop and the equivalent parameters of the motor to be tested in the loop.

[0165] Optionally, the first determination submodule is configured as follows: in the first stage when there is a freewheeling current in all three-phase windings, determine the first current response function of the winding in the first stage according to the final value of the winding current corresponding to the second electrical angle; determine the first relationship between the bus power supply voltage and the amplitude of the winding back electromotive force according to the first current response function and the first equivalent parameter of the motor to be measured, the first equivalent parameter being the equivalent parameter of the target winding; determine the first amplitude of the winding back electromotive force according to the bus power supply voltage and the first relationship; and determine the first amplitude as the amplitude of the winding back electromotive force.

[0166] Optionally, the first relationship between the bus power supply voltage and the amplitude of the winding back electromotive force is:

[0167]

[0168] Among them, U an Characterizes the magnitude of the winding back EMF, V dc represents the voltage value of the bus power supply, Δθ2 represents the position angle change of the motor to be tested in the first stage, Δθ1 represents the position angle change of the motor to be tested in the short-circuit state, t1 represents the duration of each short-circuit operation, t2 represents the duration of the first stage, α0 represents the second electrical angle, Characterize the first equivalent parameter of the motor to be tested, R s1 Characterizes the equivalent resistance of the target winding, L s1 Characterize the equivalent inductance of the target winding.

[0169] Optionally, the first determination submodule is configured to: in the second stage when there is a freewheeling current in the two-phase winding, determine the second current response function of the winding in the second stage according to the final value of the winding current corresponding to the second electrical angle; determine the second relationship between the bus power supply voltage and the amplitude of the winding back electromotive force according to the second current response function and the second equivalent parameter of the motor to be measured, the second equivalent parameter being the total equivalent parameter of the two-phase winding with the freewheeling current; determine the second amplitude of the winding back electromotive force according to the bus power supply voltage and the second relationship; and determine the second amplitude as the amplitude of the winding back electromotive force.

[0170] Optionally, the second relationship between the bus power supply voltage and the amplitude of the winding back electromotive force is:

[0171]

[0172] Among them, U an Characterizes the magnitude of the winding back EMF, V dcrepresents the voltage value of the bus power supply, α0 represents the second electrical angle, Δθ1 represents the position angle change of the motor to be tested in the short-circuit state, t1 represents the duration of each short-circuit operation, t3 represents the duration of the second stage, m represents the ratio of the winding current at the end of the first stage to the final value of the winding current corresponding to the second electrical angle, Characterize the second equivalent parameter of the motor under test, R s1 +R s2 The sum of the equivalent resistances of the two-phase windings with freewheeling current, L s1 +L s2 Characterizes the sum of the equivalent inductances of the two-phase windings with freewheeling current.

[0173] Optionally, the first determination submodule is configured as follows: in the first stage when there is a freewheeling current in all three-phase windings, determine the first current response function of the winding in the first stage according to the final value of the winding current corresponding to the second electrical angle; determine the first relationship between the bus power supply voltage and the amplitude of the winding back electromotive force according to the first current response function and the first equivalent parameter of the motor to be measured, the first equivalent parameter being the equivalent parameter of the target winding; determine the first amplitude of the winding back electromotive force according to the bus power supply voltage and the first relationship; in the second stage when there is a freewheeling current in the two-phase winding, determine the second current response function of the winding in the second stage according to the final value of the winding current corresponding to the second electrical angle; determine the second relationship between the bus power supply voltage and the amplitude of the winding back electromotive force according to the second current response function and the second equivalent parameter of the motor to be measured, the second equivalent parameter being the total equivalent parameter of the two-phase winding with the freewheeling current; determine the second amplitude of the winding back electromotive force according to the bus power supply voltage and the second relationship; determine the amplitude of the winding back electromotive force according to the first amplitude and the second amplitude.

[0174] Optionally, the second determination submodule is configured to: determine the function of the winding back electromotive force according to the changing trend of the winding back electromotive force and the amplitude of the winding back electromotive force; if the function of the winding back electromotive force is not a sinusoidal function, determine that the motor to be tested has a demagnetization fault.

[0175] Optionally, the motor demagnetization fault detection device 1000 may further include:

[0176] The third determination module is configured to determine the equivalent parameters of the motor to be tested by the following formula:

[0177]

[0178] Wherein, α0 represents the second electrical angle, t1 represents the duration of each short-circuit operation, and Δθ1 represents the position angle change of the motor to be tested in the short-circuit state.

[0179] Optionally, the first determination module 1001 is configured to: divide the electrical cycle of the current operating condition of the motor to be measured to obtain multiple electrical angle areas; determine the starting electrical angle of each electrical angle area as the first electrical angle to obtain multiple first electrical angles.

[0180] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0181] The present disclosure also provides a computer-readable storage medium having computer program instructions stored thereon. When the program instructions are executed by a processor, the steps of the method for detecting motor demagnetization fault provided by the present disclosure are implemented.

[0182] The present disclosure also provides an electronic device, comprising: a processor;

[0183] a memory for storing processor-executable instructions;

[0184] Wherein, the processor is configured to execute the instructions to implement the steps of the method for detecting motor demagnetization fault described in the present disclosure.

[0185] Illustratively, the electronic device may be a vehicle. Fig.11 1 is a block diagram of a vehicle according to an exemplary embodiment. For example, vehicle 1100 may be a hybrid vehicle, a non-hybrid vehicle, an electric vehicle, a fuel cell vehicle, or other types of vehicles. Vehicle 1100 may be an autonomous vehicle, a semi-autonomous vehicle, or a non-autonomous vehicle.

[0186] Reference Fig.11 , the vehicle 1100 may include various subsystems, such as an infotainment system 1110, a perception system 1120, a decision control system 1130, a drive system 1140, and a computing platform 1150. The vehicle 1100 may also include more or fewer subsystems, and each subsystem may include multiple components. In addition, each subsystem and each component of the vehicle 1100 may be interconnected by wire or wireless means.

[0187] In some embodiments, the infotainment system 1110 may include a communication system, an entertainment system, and a navigation system, etc.

[0188] The perception system 1120 may include several sensors for sensing information about the environment around the vehicle 1100. For example, the perception system 1120 may include a global positioning system (the global positioning system may be a GPS system, or a Beidou system or other positioning systems), an inertial measurement unit (IMU), a laser radar, a millimeter wave radar, an ultrasonic radar, and a camera.

[0189] The decision control system 1130 may include a computing system, a vehicle controller, a steering system, a throttle, and a braking system.

[0190] The drive system 1140 may include components that provide powered motion for the vehicle 1100. In one embodiment, the drive system 1140 may include an engine, an energy source, a transmission system, and wheels. The engine may be one or a combination of an internal combustion engine, an electric motor, and an air compression engine. The engine is capable of converting energy provided by the energy source into mechanical energy.

[0191] Some or all functions of the vehicle 1100 are controlled by a computing platform 1150. The computing platform 1150 may include at least one processor 1151 and a memory 1152, and the processor 1151 may execute instructions 1153 stored in the memory 1152.

[0192] The processor 1151 may be any conventional processor, such as a commercially available CPU. The processor may also include a graphics processor (Graphic Process Unit, GPU), a field programmable gate array (Field Programmable Gate Array, FPGA), a system on chip (System on Chip, SOC), an application specific integrated circuit (Application Specific Integrated Circuit, ASIC) or a combination thereof.

[0193] Memory 1152 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk or optical disk.

[0194] In addition to instructions 1153 , memory 1152 may also store data, such as road maps, route information, and data such as the location, direction, and speed of the vehicle. The data stored in memory 1152 may be used by computing platform 1150 .

[0195] In the embodiment of the present disclosure, the processor 1151 may execute instruction 1153 to complete all or part of the steps of the above-mentioned method for detecting motor demagnetization fault.

[0196] In another exemplary embodiment, a computer program product is further provided. The computer program product includes a computer program executable by a programmable device. The computer program has a code portion for executing the above-mentioned method for detecting motor demagnetization fault when executed by the programmable device.

[0197] In addition, the word "exemplary" is used herein to indicate serving as an example, instance, or diagram. Any aspect or design described as "exemplary" in this article is not necessarily understood to be advantageous compared to other aspects or designs. On the contrary, the use of the word exemplary is intended to present concepts in a specific way. As used herein, the term "or" is intended to represent an inclusive "or" rather than an exclusive "or". That is, unless otherwise specified or clear from the context, "X applies A or B" is intended to represent any one of the natural inclusive arrangements. That is, if X applies A; X applies B; or X applies both A and B, "X applies A or B" is satisfied under any of the aforementioned examples. In addition, unless otherwise specified or clearly pointed to a singular form from the context, the articles "one" and "an" as used in this application and the appended claims are generally understood to mean "one or more".

[0198] Likewise, although the present disclosure has been shown and described with respect to one or more implementations, equivalent variations and modifications will occur to those skilled in the art after reading and understanding the specification and drawings. The present disclosure includes all such modifications and variations and is limited only by the scope of the claims. In particular, with respect to the various functions performed by the components (e.g., elements, resources, etc.) described above, unless otherwise noted, the terms used to describe such components are intended to correspond to any component (functionally equivalent) that performs the specific functions of the described components, even if the structure is not equivalent to the disclosed structure. In addition, although the specific features of the present disclosure may have been disclosed with respect to only one of several implementations, such features may be combined with one or more other features of other implementations as may be desired and conducive to any given or specific application. In addition, with respect to "including", "having", "having", "having", or variations thereof used in the specific embodiments or claims, such terms are intended to be inclusive in a manner similar to the term "comprising".

[0199] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

[0200] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A method for detecting a motor demagnetization fault, characterized in that: include: Determining a plurality of first electrical angles within an electrical cycle of a current operating condition of the motor to be tested; For each of the first electrical angles, the first electrical angle is determined as the initial rotor angle of the motor to be tested, and a short-circuit operation is performed to put the winding of the motor to be tested in a short-circuit state, and a final winding current value corresponding to the initial rotor angle is obtained, and the final winding current value is the winding current of the target winding when the short-circuit operation is terminated; Whether a demagnetization fault occurs in the motor to be tested is determined according to the final value of the winding current corresponding to each of the initial angles of the rotor.

2. The method according to claim 1, characterized in that The step of determining whether a demagnetization fault occurs in the motor to be tested according to the final value of the winding current corresponding to each of the initial angles of the rotor comprises: Determining the winding back electromotive force information of the motor to be tested within the electrical cycle according to the final value of the winding current corresponding to each of the initial angles of the rotor; Determine whether a demagnetization fault occurs in the motor to be tested according to the back electromotive force information of the motor to be tested.

3. The method according to claim 2, characterized in that The winding back electromotive force information includes a change trend of the winding back electromotive force; the winding back electromotive force information of the motor to be tested within the electrical cycle is determined according to the final value of the winding current corresponding to each of the initial angles of the rotor, including: According to the final value of the winding current corresponding to each of the initial angles of the rotor, a variation trend of the final value of the winding current with the initial angle of the rotor within the electrical cycle is determined, and the variation trend is determined as a variation trend of the winding back electromotive force of the motor to be measured.

4. The method according to claim 3, characterized in that The step of determining whether a demagnetization fault occurs in the motor to be tested according to the back electromotive force information of the winding of the motor to be tested comprises: If the variation trend of the winding back electromotive force does not present a sinusoidal variation trend, it is determined that a demagnetization fault occurs in the motor to be tested.

5. The method according to claim 3, characterized in that: The step of determining a plurality of first electrical angles within an electrical cycle of a current operating condition of the motor to be tested comprises: According to the speed of the motor to be tested, the motor impedance angle is estimated The value of and the angle ρ, where ω represents the speed of the motor to be tested, t represents the time, Characterizing equivalent parameters of the motor to be tested; The estimated resistance impedance angle The difference between the value of and the angle ρ is determined as the second electrical angle; In an electrical cycle of the motor to be tested, a plurality of first electrical angles are determined, and there is at least one second electrical angle among the plurality of first electrical angles.

6. The method according to claim 5, characterized in that The winding back electromotive force information includes the amplitude of the winding back electromotive force; the detection method is applied to an electric drive system, the electric drive system includes a bus power supply, the motor to be tested and an inverter connected in sequence, the midpoints of the three-phase bridge arms included in the inverter are respectively connected to the three-phase windings included in the motor to be tested, and the upper bridge arm and the lower bridge arm of each bridge arm respectively include a group of parallel switch tubes and diodes; The step of determining the winding back electromotive force information of the motor to be tested within the electrical cycle according to the final value of the winding current corresponding to each of the initial angles of the rotor further includes: For the second electrical angle, when the short-circuit operation is terminated, each switch tube in the three-phase bridge arm is controlled to be in an off state, so that the three-phase winding forms a loop with the bus power supply through the diodes in the three-phase bridge arm; The amplitude of the back electromotive force of the winding is determined according to the current response function of the winding in the loop and the equivalent parameters of the motor to be measured in the loop.

7. The method according to claim 6, characterized in that Determining the amplitude of the back electromotive force of the winding according to the current response function of the winding in the loop and the equivalent parameters of the motor to be measured in the loop includes: In the first stage when the freewheeling current exists in the three-phase windings, a first current response function of the winding in the first stage is determined according to the final value of the winding current corresponding to the second electrical angle; Determining a first relationship between a bus power supply voltage and an amplitude of a winding back electromotive force according to the first current response function and a first equivalent parameter of the motor to be measured, wherein the first equivalent parameter is an equivalent parameter of the target winding; Determining a first amplitude of a winding back electromotive force according to the bus power supply voltage and the first relationship; The first amplitude is determined as the amplitude of the winding back electromotive force.

8. The method according to claim 7, characterized in that The first relationship between the bus supply voltage and the amplitude of the winding back electromotive force is: Among them, U an Characterizes the magnitude of the winding back EMF, V dc represents the voltage value of the bus power supply, Δθ2 represents the position angle change of the motor to be tested in the first stage, Δθ1 represents the position angle change of the motor to be tested in the short-circuit state, t1 represents the duration of each short-circuit operation, t2 represents the duration of the first stage, α0 represents the second electrical angle, Characterize the first equivalent parameter of the motor to be tested, R s1 Characterizes the equivalent resistance of the target winding, L s1 Characterize the equivalent inductance of the target winding.

9. The method according to claim 6, characterized in that Determining the amplitude of the back electromotive force of the winding according to the current response function of the winding in the loop and the equivalent parameters of the motor to be measured in the loop includes: In the second stage when the freewheeling current exists in the two-phase windings, determining the second current response function of the winding in the second stage according to the final value of the winding current corresponding to the second electrical angle; Determine a second relationship between the bus power supply voltage and the amplitude of the winding back electromotive force according to the second current response function and a second equivalent parameter of the motor to be measured, wherein the second equivalent parameter is a total equivalent parameter of the two-phase winding with freewheeling current; determining a second amplitude of the winding back electromotive force according to the bus power supply voltage and the second relationship; The second amplitude is determined as the amplitude of the winding back electromotive force.

10. The method according to claim 9, characterized in that The second relationship between the bus supply voltage and the amplitude of the winding back electromotive force is: Among them, U an Characterizes the magnitude of the winding back EMF, V dc represents the voltage value of the bus power supply, α0 represents the second electrical angle, Δθ1 represents the position angle change of the motor to be tested in the short-circuit state, t1 represents the duration of each short-circuit operation, t3 represents the duration of the second stage, m represents the ratio of the winding current at the end of the first stage to the final value of the winding current corresponding to the second electrical angle, Characterize the second equivalent parameter of the motor under test, R s1 +R s2 The sum of the equivalent resistances of the two-phase windings with freewheeling current, L s1 +L s2 Characterizes the sum of the equivalent inductances of the two-phase windings with freewheeling current.

11. The method according to claim 6, characterized in that Determining the amplitude of the back electromotive force of the winding according to the current response function of the winding in the loop and the equivalent parameters of the motor to be measured in the loop includes: In the first stage when the freewheeling current exists in the three-phase windings, a first current response function of the winding in the first stage is determined according to the final value of the winding current corresponding to the second electrical angle; Determining a first relationship between a bus power supply voltage and an amplitude of a winding back electromotive force according to the first current response function and a first equivalent parameter of the motor to be measured, wherein the first equivalent parameter is an equivalent parameter of the target winding; Determining a first amplitude of a winding back electromotive force according to the bus power supply voltage and the first relationship; In the second stage when the freewheeling current exists in the two-phase windings, determining the second current response function of the winding in the second stage according to the final value of the winding current corresponding to the second electrical angle; Determine a second relationship between the bus power supply voltage and the amplitude of the winding back electromotive force according to the second current response function and a second equivalent parameter of the motor to be measured, wherein the second equivalent parameter is a total equivalent parameter of the two-phase winding with freewheeling current; determining a second amplitude of the winding back electromotive force according to the bus power supply voltage and the second relationship; The amplitude of the winding back electromotive force is determined according to the first amplitude and the second amplitude.

12. The method according to any one of claims 6 to 11, characterized in that: The step of determining whether a demagnetization fault occurs in the motor to be tested according to the back electromotive force information of the winding of the motor to be tested comprises: Determining a function of the winding back electromotive force according to a variation trend of the winding back electromotive force and an amplitude of the winding back electromotive force; If the function of the winding back electromotive force is not a sinusoidal function, it is determined that a demagnetization fault occurs in the motor to be tested.

13. The method according to any one of claims 6 to 11, characterized in that: The method further comprises: The equivalent parameters of the motor to be tested are determined by the following formula: Wherein, α0 represents the second electrical angle, t1 represents the duration of each short-circuit operation, and Δθ1 represents the position angle change of the motor to be tested in the short-circuit state.

14. The method according to claim 1, characterized in that Determining multiple target electrical angles within the electrical cycle of the current operating condition of the motor to be tested includes: Divide the electrical cycle of the current operating condition of the motor to be measured to obtain multiple electrical angle regions; The starting electrical angle of each electrical angle region is determined as a first electrical angle to obtain a plurality of first electrical angles.

15. A detection device for motor demagnetization fault, characterized in that: include: A first determination module is configured to determine a plurality of first electrical angles within an electrical cycle of a current operating condition of the motor to be tested; a first acquisition module, configured to determine the first electrical angle as the rotor initial angle of the short-circuit operation of the motor to be tested for each of the first electrical angles, perform a short-circuit operation to put the winding of the motor to be tested in a short-circuit state, and obtain a winding current final value corresponding to the rotor initial angle, wherein the winding current final value is the winding current of the target winding when the short-circuit operation is terminated; The second determination module is configured to determine whether the motor to be tested has a demagnetization fault according to a final value of the winding current corresponding to each of the initial angles of the rotor.

16. An electronic device, characterized in that: include: processor; a memory for storing processor-executable instructions; The processor is configured to execute the instructions to implement the steps of the method for detecting motor demagnetization fault as described in any one of claims 1-14.

17. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for detecting a motor demagnetization fault as described in any one of claims 1 to 14 are implemented.

18. A computer program product, characterized in that The invention comprises a computer program, which, when executed by a processor, implements the steps of the method for detecting a motor demagnetization fault as claimed in any one of claims 1 to 14.

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