A method and apparatus for controlling a motor

Abstract

The application discloses a motor control method and device to avoid damage to the motor controller and other components caused by excessive counter electromotive force when the motor is in a towed state. The method is applied to a motor controller, and the method comprises the following steps: obtaining the current time electrical angle of the motor, the q-axis current and the d-axis current at the previous time when the motor is in the towed state; calculating the q-axis voltage and the d-axis voltage at the current time according to the current time electrical angle, the q-axis current and the d-axis current at the previous time, and a preset bus voltage limit; and controlling the voltage acting on the direct current bus of the motor according to the q-axis voltage and the d-axis voltage at the current time. The method limits the bus voltage to inhibit the effect of excessive counter electromotive force.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automation control, in particular to a motor control method and device. BACKGROUND

[0002] With the development of the automobile industry, permanent magnet synchronous motors are widely used in vehicles. The permanent magnet synchronous motor generates a back electromotive force when it is running, and the back electromotive force increases with the increase of the rotating speed. The excessive back electromotive force can increase the bus voltage, thereby causing damage to the motor controller and other components.

[0003] At present, the motor controller controls the output target torque value, gradually reduces the motor electromagnetic torque to the target torque value, dynamically controls the motor rotating speed, and thereby reduces the increase amplitude of the electromotive force.

[0004] However, the above method is only applicable to the scenario where the motor rotating speed can be actively controlled. In some scenarios where the vehicle is towed due to vehicle failure, such as the case where a passenger car, a bus, a logistics vehicle, etc. is towed due to failure, the motor rotating speed of the towed vehicle (i.e. the failure vehicle) is not controlled by the failure vehicle, but is determined by the towing vehicle (i.e. the wrecker). Therefore, the above method is not applicable to the application scenario of the vehicle failure being towed, and cannot meet the user demand. SUMMARY

[0005] Based on the above problems, the present application provides a motor control method and device to avoid damage to the motor controller and other components caused by excessive back electromotive force when in a towed vehicle state.

[0006] The present application discloses the following technical solutions:

[0007] The first aspect of the present application provides a motor control method applied to a motor controller, the method comprising:

[0008] When in a towed vehicle state, the current time electrical angle of the motor, the q-axis current and the d-axis current of the previous time are obtained;

[0009] According to the current time electrical angle, the q-axis current and the d-axis current of the previous time, and the preset bus voltage limit value, the q-axis voltage and the d-axis voltage of the current time are calculated;

[0010] According to the q-axis voltage and the d-axis voltage of the current time, the voltage acting on the DC bus of the motor is controlled.

[0011] In one possible implementation, the q-axis voltage and the d-axis voltage of the current time are calculated by the following formula:

[0012]

[0013] Wherein, U d(k) , U q(k) are d-axis target voltage value and q-axis target voltage value at k moment, U aim is preset bus voltage limit value, i d(k-1) , i q(k-1) are direct-axis current and quadrature-axis current of three-phase current value transformed to rotating coordinate system at k-1 moment, k is greater than or equal to 1; ω e(k) is electrical angle at current k moment; n is pole pair number of the towed motor; T is set torque limit value; R is stator resistance; and λ is Lagrange multiplier.

[0014] In one possible implementation, the method further includes:

[0015] acquiring connection state between the motor controller and the low-voltage storage battery, connection state between the motor controller and the power battery, and current motor speed;

[0016] when the connection between the motor controller and the low-voltage storage battery is connected, the connection between the motor controller and the power battery is disconnected, and the current motor speed is greater than a threshold value, controlling entering the towed vehicle state.

[0017] In one possible implementation, the method further includes:

[0018] when the indication signal of entering the towed vehicle state is received, acquiring connection state between the motor controller and the low-voltage storage battery, and connection state between the motor controller and the power battery; the indication signal of entering the towed vehicle state is sent by the button of controlling entering the towed vehicle state in response to being pressed;

[0019] when the connection between the motor controller and the low-voltage storage battery is connected, and the connection between the motor controller and the power battery is disconnected, controlling entering the towed vehicle state.

[0020] In one possible implementation, the acquiring of the electrical angle at the current moment, the q-axis current and the d-axis current of the motor includes: acquiring the electrical angle at the current moment, the q-axis current and the d-axis current of the motor collected by a sensing device.

[0021] The second aspect of the present application provides a motor control device, including:

[0022] an acquiring unit, configured to acquire the electrical angle at the current moment, the q-axis current and the d-axis current of the motor when in the towed vehicle state;

[0023] a calculating unit, configured to calculate the q-axis voltage and the d-axis voltage at the current moment according to the electrical angle at the current moment, the q-axis current and the d-axis current at the previous moment, and the preset bus voltage limit value;

[0024] a control unit configured to control a voltage applied to a DC bus of the motor according to a q-axis voltage and a d-axis voltage at the current time.

[0025] In one possible implementation, the control unit is configured to calculate the q-axis voltage and the d-axis voltage at the current time according to the following formulae:

[0026]

[0027] wherein U d(k) , U q(k) are a d-axis target voltage value and a q-axis target voltage value at the kth time, U aim is a preset bus voltage limit value, i d(k-1) , i q(k-1) are a direct-axis current and a quadrature-axis current of three-phase current values at the (k-1)th time transformed to a rotating coordinate system, k is greater than or equal to 1; ω e(k) is an electrical angle at the current kth time; n is a pole pair number of the towed motor; T is a set torque limit value; R is a stator resistance; and λ is a Lagrange multiplier.

[0028] In one possible implementation, the device further includes:

[0029] a second acquisition unit configured to acquire a connection state between a motor controller and a low-voltage storage battery, a connection state between the motor controller and a power battery, and a current motor speed;

[0030] a second control unit configured to control entering a towed vehicle state when the connection between the motor controller and the low-voltage storage battery is connected, the connection between the motor controller and the power battery is disconnected, and the current motor speed is greater than a threshold value.

[0031] In one possible implementation, the device further includes:

[0032] a third acquisition unit configured to acquire the connection state between the motor controller and the low-voltage storage battery and the connection state between the motor controller and the power battery when an instruction signal for entering the towed vehicle state is received, the instruction signal being sent by a button for controlling entering the towed vehicle state in response to a pressing operation;

[0033] a third control unit configured to control entering the towed vehicle state when the connection between the motor controller and the low-voltage storage battery is connected and the connection between the motor controller and the power battery is disconnected.

[0034] In one possible implementation, the acquisition unit is specifically configured to acquire an electrical angle of the motor at the current time, a q-axis current and a d-axis current at a previous time collected by a sensing device.

[0035] Compared with the prior art, the application has the following beneficial effects:

[0036] The motor control method provided in the application obtains the current time electrical angle of the motor, the q-axis current and the d-axis current of the previous time when the motor is in the towed vehicle state; calculates the q-axis voltage and the d-axis voltage of the current time according to the current time electrical angle, the q-axis current and the d-axis current of the previous time and the preset bus voltage limit; and controls the voltage acting on the DC bus of the motor according to the q-axis voltage and the d-axis voltage of the current time. By limiting the bus voltage, the effect of the excessive back electromotive force is inhibited. In the vehicle towed vehicle scene, the damage of the excessive back electromotive force of the motor to the motor controller and other components can be avoided. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0038] Figure 1 A motor control method flow chart provided in the embodiments of the present application;

[0039] Figure 2 A hardware structure diagram of the motor control system provided in the embodiments of the present application;

[0040] Figure 3 A motor control device structure diagram provided in the embodiments of the present application. DETAILED DESCRIPTION

[0041] As described above, the current method for solving the problem of excessive back electromotive force of the motor is that the motor controller controls the output target torque value, gradually reduces the motor electromagnetic torque to the target torque value, dynamically controls the motor speed, and thereby reduces the increase amplitude of the electromotive force.

[0042] However, in the application scene of towing the vehicle due to vehicle failure, the motor speed of the towed vehicle (i.e. the failure vehicle) is not controlled by the failure vehicle, but is determined by the towing vehicle (i.e. the wrecker). Therefore, the above method is not applicable to the application scene of towing the vehicle due to vehicle failure, and cannot meet the user demand.

[0043] The embodiment of the application provides a motor control method, which is applied to a motor controller. When being in a towed vehicle state, an electric angle of a current moment of the motor, q-axis current and d-axis current of a previous moment are acquired. According to the electric angle of the current moment, the q-axis current and the d-axis current of the previous moment and a preset bus voltage limit value, q-axis voltage and d-axis voltage of the current moment are calculated. According to the q-axis voltage and the d-axis voltage of the current moment, a voltage acting on a direct current bus of the motor is controlled. By limiting the bus voltage, the effect of excessive counter electromotive force is inhibited. In the towed vehicle scene, the motor controller and other components are prevented from being damaged by the excessive counter electromotive force of the motor.

[0044] In order for those skilled in the art to better understand the scheme of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0045] Referring to Figure 1 , the figure is a flow chart of a motor control method provided by the embodiment of the present application. The method is applied to a motor controller. As shown in Figure 1 , the method comprises the following steps.

[0046] S110, when being in a towed vehicle state, acquiring an electric angle of a current moment of the motor, q-axis current and d-axis current of a previous moment.

[0047] When being in the towed vehicle state, the whole vehicle is powered by low voltage.

[0048] In the magnetic field rotating coordinate system, the d-axis is a direct axis, and the q-axis is a quadrature axis.

[0049] S120, according to the electric angle of the current moment, the q-axis current and the d-axis current of the previous moment and a preset bus voltage limit value, calculating q-axis voltage and d-axis voltage of the current moment.

[0050] Since large counter electromotive force can pull up the bus voltage and cause damage to electronic devices, in order to make the bus voltage meet the expectation of not causing damage, the preset bus voltage limit value is in the expected range, so that the bus voltage generated by the motor controller output voltage added to the motor is less than the preset bus voltage limit value.

[0051] In some embodiments, the q-axis voltage and the d-axis voltage of the current moment are calculated by the following formula:

[0052]

[0053] wherein, U d(k) , Uq(k) D-axis target voltage value, Q-axis target voltage value at k moment, respectively, U aim is bus voltage limit value, i d(k-1) , i q(k-1) is the direct-axis current, quadrature-axis current of three-phase current value transformed to rotating coordinate system at k-1 moment, k is greater than or equal to 1; ω e(k) is the current k moment electrical angle; n is the number of pairs of poles of the dragged motor; T is the set torque limit value; R is the stator resistance; λ is the Lagrange multiplier.

[0054] The specific calculation process of the above formula is briefly introduced as follows:

[0055] In order to limit the bus voltage, the target function about the current moment q-axis voltage and d-axis voltage and the preset bus voltage limit value is established:

[0056]

[0057] Among them, U d(k) , U q(k) D-axis target voltage value, Q-axis target voltage value at k moment, respectively, U aim is the preset bus voltage limit value, k is greater than or equal to 1.

[0058] The constraint condition of the motor in the dragged state is selected:

[0059]

[0060] Among them, U d(k) , U q(k) D-axis target voltage value, Q-axis target voltage value at k moment, respectively, U aim is the bus voltage limit value, i d(k-1) , i q(k-1) is the direct-axis current, quadrature-axis current of three-phase current value transformed to rotating coordinate system at k-1 moment, k is greater than or equal to 1; ω e(k) is the current k moment electrical angle; n is the number of pairs of poles of the dragged motor; T is the set torque limit value; R is the stator resistance.

[0061] Combined with the above target function, constraint condition and Lagrange multiplier method, the expression can be constructed:

[0062]

[0063] The first order derivative of the expression H is calculated. The solution of the first order derivative of H(U d(k) , U q(k) , λ) is equal to zero, that is:

[0064]

[0065] wherein, U d(k) , U q(k) are the D-axis target voltage value and the Q-axis target voltage value at the k time, respectively, U aim is the bus voltage limit value, i d(k-1) , i q(k-1) are the direct-axis current and the quadrature-axis current of the three-phase current value at the k-1 time transformed to the rotating coordinate system, k is greater than or equal to 1; ω e(k) is the electrical angle at the current k time; n is the pole pair number of the motor being towed; T is the set torque limit value; R is the stator resistance; and λ is the Lagrange multiplier.

[0066] The q-axis voltage and the d-axis voltage at the current time can be obtained through the above calculation formula.

[0067] S130, according to the q-axis voltage and the d-axis voltage at the current time, control the voltage acting on the DC bus of the motor.

[0068] The motor control method provided by the embodiments of the present application, when in the towed vehicle state, obtains the electrical angle at the current time of the motor, the q-axis current and the d-axis current at the previous time; according to the electrical angle at the current time, the q-axis current and the d-axis current at the previous time, and the preset bus voltage limit value, calculates the q-axis voltage and the d-axis voltage at the current time; according to the q-axis voltage and the d-axis voltage at the current time, controls the voltage acting on the DC bus of the motor. By limiting the bus voltage, the effect of the overlarge back electromotive force is suppressed. The damage of the motor controller and other components caused by the overlarge back electromotive force of the motor in the towed vehicle scene is avoided.

[0069] In one example, the control method further comprises monitoring the three-phase current, the motor temperature, the motor controller temperature and the motor controller hardware state information, and prompting the state of the motor system during the towing process according to the monitoring result. When the motor temperature, the motor controller temperature is greater than the corresponding preset temperature threshold, and / or the motor hardware state information is abnormal, the towing driver is prompted, so as to realize the safe monitoring of the state of the motor system.

[0070] When the vehicle fails and needs to be towed, the motor controller of the failed vehicle can switch to the control logic of the towed vehicle state in two ways: manually pressing the button to enter the towed vehicle state, and automatically switching under the condition of meeting the towed vehicle.

[0071] In some embodiments, the way of automatically switching under the condition of meeting the towed vehicle is as follows:

[0072] Obtain the connection state between the motor controller and the low-voltage storage battery, the connection state between the motor controller and the power battery, and the current motor speed;

[0073] When the connection between the motor controller and the low-voltage battery is connected, the connection between the motor controller and the power battery is disconnected, and the current speed of the motor is greater than a threshold, the control enters the towed vehicle state.

[0074] In some embodiments, the way of manually pressing the button to enter the towed vehicle state is as follows:

[0075] When receiving an indication signal of entering the towed vehicle state, the connection state between the motor controller and the low-voltage battery and the connection state between the motor controller and the power battery are acquired; the indication signal of entering the towed vehicle state is sent by the button of controlling entering the towed vehicle state in response to the operation of being pressed.

[0076] When the connection between the motor controller and the low-voltage battery is connected, the connection between the motor controller and the power battery is disconnected, the control enters the towed vehicle state.

[0077] Referring to Figure 2 , the figure is a hardware structure schematic diagram of a motor control system provided by the embodiment of the application. The system applies the motor control method provided by the embodiment of the application to control the motor when entering the towed vehicle state.

[0078] As Figure 2 shown, the motor control system comprises a low-voltage battery, a power battery, and a button for manually operating to enter the towed vehicle state.

[0079] The power supply switch K3 of the low-voltage battery and the motor controller is controlled by the pass signal 3 of the button, and the button state signal passes through the signal line 4 as the motor controller control signal input; the motor controller controls the signal lamp and the buzzer on the instrument through the signal line 2, the green lamp represents normal operation, the yellow lamp prompts to drive at a low speed and the buzzer sounds, the red lamp represents parking and the buzzer sounds, and the sound is different from that when the lamp is yellow; the signal line 1 is the resolver line between the motor controller and the motor, including the motor temperature, the rotor position and other signals; the motor controller acquires the closing or opening state of the power supply switches K1 and K2 of the power battery and the motor controller through the signal line 5, and the state can be directly recognized by the motor controller or recognized by other controllers and then forwarded to the motor controller. The motor controller controls the motor through the three-phase line.

[0080] The motor controller can enter the towed vehicle state when the button is manually pressed or the towed vehicle condition is automatically judged, and after entering the towed vehicle state, the motor is controlled by applying the motor control method provided by the embodiment of the application.

[0081] In one example, before the trailer is towed, the person manually presses the rocker button, the low-voltage battery is closed with the power supply switch K3 of the motor controller, that is, the low-voltage power supply. And the motor controller receives the signal of the rocker button being pressed, obtains the switch state of the switches K1 and K2, if the switches 1 and 2 are not closed at the same time, the instrument green light is on, prompting entering the towed vehicle state; if the switches 1 and 2 are closed at the same time, the towed vehicle state is prohibited, the instrument red light is on, and the buzzer emits an alarm.

[0082] In one example, the motor controller automatically determines that it is in a low-voltage power supply state, that the obtained absolute value of the motor speed is greater than a preset threshold, and that the obtained switches K1 and K2 are not closed at the same time, and automatically enters the towed vehicle state.

[0083] In some embodiments, obtaining the current time electrical angle of the motor, the q-axis current and the d-axis current at the previous time, comprises: obtaining the current time electrical angle of the motor, the q-axis current and the d-axis current at the previous time collected by a sensing device. For example, the sensing device can be a speed sensor, a current sensor.

[0084] Referring to Figure 3 , the figure is a structure diagram of a motor control device provided by the embodiment of the application. As Figure 3 shown, the device comprises:

[0085] The obtaining unit 310 is configured to, when in the towed vehicle state, obtain the current time electrical angle of the motor, the q-axis current and the d-axis current at the previous time;

[0086] The calculation unit 320 is configured to calculate the q-axis voltage and the d-axis voltage at the current time according to the current time electrical angle, the q-axis current and the d-axis current at the previous time, and a preset bus voltage limit value;

[0087] The control unit 330 is configured to control the voltage acting on the direct current bus of the motor according to the q-axis voltage and the d-axis voltage at the current time.

[0088] In some embodiments, the calculation unit calculates the q-axis voltage and the d-axis voltage at the current time according to the following formula:

[0089]

[0090] wherein, U d(k) , U q(k) are the D-axis target voltage value and the Q-axis target voltage value at k time, U aim is the bus voltage limit value, i d(k-1) , i q(k-1) are the direct-axis current and the quadrature-axis current of the three-phase current value at k-1 time transformed to the rotating coordinate system, and k is greater than or equal to 1; ω e(k)is the electrical angle at the current k moment; n is the pole pair number of the motor; T is the set torque limit value; R is the stator resistance; and λ is the Lagrange multiplier.

[0091] In some embodiments, the device further comprises a monitoring unit for monitoring the motor temperature, the motor controller temperature and the motor controller hardware state information, and prompting the state of the motor system during the towing process according to the monitoring result.

[0092] In some embodiments, the conditions in the towing state include:

[0093] The motor controller is connected with the low-voltage storage battery, and the motor controller is disconnected with the power battery.

[0094] In some embodiments, the obtaining unit is specifically configured to obtain the electrical angle of the motor at the current moment, the q-axis current and the d-axis current at the previous moment collected by the sensing device.

[0095] Those skilled in the art can understand that the motor control device provided by the embodiments of the present application can also implement other methods as described in the motor control method provided by the embodiments of the present application, which will not be repeated here.

[0096] The motor control device provided by the embodiments of the present application, when in the towing state, obtains the electrical angle of the motor at the current moment, the q-axis current and the d-axis current at the previous moment; calculates the q-axis voltage and the d-axis voltage at the current moment according to the electrical angle at the current moment, the q-axis current and the d-axis current at the previous moment, and the preset bus voltage limit value; and controls the voltage acting on the DC bus of the motor according to the q-axis voltage and the d-axis voltage at the current moment. By limiting the bus voltage, the effect of excessive back electromotive force is suppressed. In the towing scene of the vehicle, the damage of the motor controller and other components caused by the excessive back electromotive force of the motor is avoided.

[0097] It should be noted that each of the embodiments in the present specification is described in a progressive manner, and the same and similar parts of each embodiment can be referred to each other, and each embodiment focuses on the difference from other embodiments. Especially, for the device and system embodiments, since they are basically similar to the method embodiments, they are described more simply, and the relevant parts can be referred to the part of the description of the method embodiments. The above-described device and system embodiments are only illustrative, and the units described as separate components can be or can not be physically separated, and the components described as units can be or can not be physical units, that is, they can be located in one place, or can be distributed on multiple network units. According to the actual needs, part or all of the modules can be selected to achieve the purpose of the present embodiment scheme. Those skilled in the art can understand and implement without creative labor.

[0098] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A motor control method, characterized in that, Applied to a motor controller, the method includes: When in a towed state, obtain the current electrical angle of the motor, the q-axis current and the d-axis current of the previous moment; Calculate the q-axis voltage and d-axis voltage at the current moment based on the electrical angle at the current moment, the q-axis current and d-axis current at the previous moment, and the preset bus voltage limit. Based on the current q-axis voltage and d-axis voltage, control the voltage applied to the DC bus of the motor; The q-axis voltage and d-axis voltage at the current moment are calculated using the following formulas: in, , These represent the target voltage values ​​along the d-axis and q-axis at time k, respectively. To preset the bus voltage limit, , These are the direct-axis current and quadrature-axis current of the three-phase current at time k-1, transformed into the rotating coordinate system, where k is greater than or equal to 1; is the electrical angle at time k; n is the number of pole pairs of the driven motor; T is the set torque limit. Stator resistance; It is a Lagrange multiplier.

2. The method according to claim 1, characterized in that, The method further includes: Obtain the connection status between the motor controller and the low-voltage battery, the connection status between the motor controller and the power battery, and the current motor speed; When the connection between the motor controller and the low-voltage battery is established, the connection between the motor controller and the power battery is disconnected, and the current motor speed is greater than the threshold, the control enters the towing state.

3. The method according to claim 1, characterized in that, The method further includes: Upon receiving an indication signal to enter the towing state, the system acquires the connection status between the motor controller and the low-voltage battery, and the connection status between the motor controller and the power battery; the indication signal to enter the towing state is sent by the button controlling the entry into the towing state in response to being pressed. When the connection between the motor controller and the low-voltage battery is established, and the connection between the motor controller and the power battery is disconnected, the control enters the towing state.

4. The method according to claim 1, characterized in that, The acquisition of the current electrical angle of the motor, the q-axis current and the d-axis current of the previous moment includes: acquiring the current electrical angle of the motor, the q-axis current and the d-axis current of the previous moment collected by the sensing device.

5. A motor control device, characterized in that, include: The first acquisition unit is used to acquire the current electrical angle of the motor, the q-axis current and the d-axis current of the previous moment when the motor is in a towed state. The calculation unit is used to calculate the q-axis voltage and d-axis voltage at the current moment based on the electrical angle at the current moment, the q-axis current and d-axis current at the previous moment, and the preset bus voltage limit. The first control unit is used to control the voltage applied to the DC bus of the motor based on the q-axis voltage and d-axis voltage at the current moment. The calculation unit calculates the q-axis voltage and d-axis voltage at the current moment according to the following formula: in, , These represent the target voltage values ​​on the q-axis and d-axis at time k, respectively. To preset the bus voltage limit, , These are the direct-axis current and quadrature-axis current of the three-phase current at time k-1, transformed into the rotating coordinate system, where k is greater than or equal to 1; is the electrical angle at time k; n is the number of pole pairs of the driven motor; T is the set torque limit. Stator resistance; It is a Lagrange multiplier.

6. The apparatus according to claim 5, characterized in that, The device further includes: The second acquisition unit is used to acquire the connection status between the motor controller and the low-voltage battery, the connection status between the motor controller and the power battery, and the current motor speed. The second control unit is used to connect the motor controller to the low-voltage battery, disconnect the motor controller from the power battery, and control the vehicle to enter the towing state when the current motor speed is greater than a threshold.

7. The apparatus according to claim 5, characterized in that, The device further includes: The third acquisition unit is used to acquire the connection status between the motor controller and the low-voltage battery, and the connection status between the motor controller and the power battery when it receives the indication signal for entering the towing state; the indication signal for entering the towing state is sent by the button controlling the entry into the towing state in response to the operation of being pressed. The third control unit is used to connect the motor controller to the low-voltage battery and to disconnect the motor controller from the power battery, thereby controlling the vehicle to enter the towing state.

8. The apparatus according to claim 5, characterized in that, The acquisition unit is specifically used to acquire the current electrical angle of the motor, the q-axis current and the d-axis current of the previous moment, which are collected by the sensing device.

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