Control method of permanent magnet auxiliary synchronous reluctance motor and related assembly

Abstract

The invention discloses a control method of a permanent magnet auxiliary synchronous reluctance motor and a related assembly, and relates to the field of motor control, the target torque current of the permanent magnet auxiliary synchronous reluctance motor is determined, and the torque current of the permanent magnet auxiliary synchronous reluctance motor is adjusted to be the target torque current; adjustment of the excitation current of the motor is divided into a constant torque operation area and a weak magnetic operation area, when the motor is in the constant torque operation area, the excitation current is adjusted to be the target excitation current corresponding to the maximum torque current ratio, and it is guaranteed that the output voltage of the motor is smaller on the premise that the working condition is not affected; the control of the motor is more efficient and energy-saving; and when the motor is in the weak magnetic operation area, jointly adjusting the excitation current according to the target excitation current and the excitation current increment so as to control the direct-current voltage in the steady-state equation of the permanent magnet auxiliary synchronous reluctance, ensure that the output voltage of the motor is constant, and realize high-dynamic response in the weak magnetic operation area.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and particularly to a control method for a permanent magnet assisted synchronous reluctance motor and related components. Background Art

[0002] A permanent magnet assisted synchronous reluctance motor is a motor that utilizes the reluctance characteristic to assist the operation of a synchronous motor. Due to its advantages of high power density, high power factor, strong overload capacity, and high efficiency, the permanent magnet assisted synchronous reluctance motor has been gradually widely used. However, there are few mature and stable control strategies for permanent magnet assisted synchronous reluctance motors on the market. Summary of the Invention

[0003] The object of the present invention is to provide a control method for a permanent magnet assisted synchronous reluctance motor and related components, which can achieve maximum torque current ratio control in the constant torque operation region and high dynamic response control in the field weakening operation region while realizing stable control of the permanent magnet assisted synchronous reluctance motor, making the control of the motor more efficient and energy-saving.

[0004] To solve the above technical problems, the present invention provides a control method for a permanent magnet assisted synchronous reluctance motor, including:

[0005] Determine the target torque current of the permanent magnet assisted synchronous reluctance motor, and adjust the torque current of the permanent magnet assisted synchronous reluctance motor to the target torque current;

[0006] Determine the target field current when the permanent magnet assisted synchronous reluctance motor reaches the maximum torque current ratio;

[0007] When the permanent magnet assisted synchronous reluctance motor is in the constant torque operation region, adjust the field current of the permanent magnet assisted synchronous reluctance motor to the target field current;

[0008] When the permanent magnet assisted synchronous reluctance motor is in the field weakening operation region, determine the field current increment of the permanent magnet assisted synchronous reluctance motor, and adjust the field current according to the field current increment and the target field current to control the DC voltage in the steady-state equation of the permanent magnet assisted synchronous reluctance.

[0009] Optionally, the determining the target field current when the permanent magnet assisted synchronous reluctance motor reaches the maximum torque current ratio includes: determining the target field current based on the maximum torque current ratio determination formula; the maximum torque current ratio determination formula is:

[0010]

[0011] Wherein, is the target field current, ψ m is the permanent magnet flux linkage, Ld is the direct-axis inductance of the permanent magnet assisted synchronous reluctance motor, L q is the quadrature-axis inductance of the permanent magnet assisted synchronous reluctance motor, i d * is the target torque current.

[0012] Optionally, the determination process of the maximum torque current ratio determination formula includes:

[0013] Based on the relationship between the stator current amplitude of the permanent magnet assisted synchronous reluctance motor and the direct-axis current, and the relationship between the stator current amplitude and the quadrature-axis current, determine the relationship between the torque of the permanent magnet assisted synchronous reluctance motor and the current vector angle;

[0014] Based on the partial derivative of the relationship between the torque of the permanent magnet assisted synchronous reluctance motor and the current vector angle with respect to the current vector angle, determine the maximum torque current ratio determination formula.

[0015] Optionally, it further includes:

[0016] When the permanent magnet assisted synchronous reluctance motor is in the constant torque operation region and it is determined that the target excitation current is less than the preset excitation current threshold, adjust the excitation current of the permanent magnet assisted synchronous reluctance motor to the preset excitation current threshold.

[0017] Optionally, it further includes:

[0018] When the permanent magnet assisted synchronous reluctance motor is in the no-load operation state and the rotor position of the permanent magnet assisted synchronous reluctance motor is determined by using the sensorless algorithm, increase the excitation current to the preset target excitation current.

[0019] Optionally, determining the excitation current increment of the permanent magnet assisted synchronous reluctance motor includes:

[0020] Input the voltage difference obtained by subtracting the actual output voltage from the maximum output voltage of the permanent magnet assisted synchronous reluctance motor into the voltage regulator, and determine the excitation current increment according to the output of the voltage regulator.

[0021] Optionally, determining the excitation current increment according to the output of the voltage regulator includes:

[0022] When the output of the voltage regulator is negative and the output is not less than the preset output threshold, use the output of the voltage regulator as the excitation current increment;

[0023] When the output of the voltage regulator is negative and the output is less than the preset output threshold, use the preset output as the excitation current increment.

[0024] To solve the above technical problems, the present application also provides a control system for a permanent magnet assisted synchronous reluctance motor, including:

[0025] A torque current regulation unit, configured to determine a target torque current of the permanent magnet assisted synchronous reluctance motor and regulate the torque current of the permanent magnet assisted synchronous reluctance motor to the target torque current;

[0026] A target field current determination unit, configured to determine a target field current when the permanent magnet assisted synchronous reluctance motor reaches the maximum torque current ratio;

[0027] A first field current regulation unit, configured to regulate the field current of the permanent magnet assisted synchronous reluctance motor to the target field current when the permanent magnet assisted synchronous reluctance motor is in the constant torque operation region;

[0028] A second field current regulation unit, configured to determine an increment of the field current of the permanent magnet assisted synchronous reluctance motor when the permanent magnet assisted synchronous reluctance motor is in the field weakening operation region, and regulate the field current according to the increment of the field current and the target field current to control the DC voltage in the steady-state equation of the permanent magnet assisted synchronous reluctance.

[0029] To solve the above technical problems, the present application also provides a control device for a permanent magnet assisted synchronous reluctance motor, including:

[0030] A memory, configured to store a computer program;

[0031] A processor, configured to implement the steps of the control method for the permanent magnet assisted synchronous reluctance motor according to any one of the above when executing the computer program.

[0032] To solve the above technical problems, the present application also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the control method for the permanent magnet assisted synchronous reluctance motor according to any one of the above are implemented.

[0033] The beneficial effects of the present application are as follows: A control method and related components for a permanent magnet assisted synchronous reluctance motor are provided. The target torque current of the permanent magnet assisted synchronous reluctance motor is determined, and the torque current of the permanent magnet assisted synchronous reluctance motor is adjusted to the target torque current. The adjustment of the excitation current of the motor is divided into two parts: the constant torque operation area and the field weakening operation area. When the motor is in the constant torque operation area, the excitation current is adjusted to the target excitation current corresponding to the maximum torque current ratio, ensuring a smaller output voltage of the motor without affecting the working conditions, making the control of the motor more efficient and energy-saving. When the motor is in the field weakening operation area, the excitation current is jointly adjusted according to the target excitation current and the excitation current increment to control the DC voltage in the steady-state equation of the permanent magnet assistance synchronous reluctance, ensuring a constant output voltage of the motor and achieving a high dynamic response in the field weakening operation area. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the prior art and the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0035] Figure 1 It is a flowchart of a control method for a permanent magnet assisted synchronous reluctance motor provided by the present application;

[0036] Figure 2 It is a main circuit topology diagram of a frequency converter driving a permanent magnet assisted synchronous reluctance motor provided by the present application;

[0037] Figure 3 It is a control block diagram of a permanent magnet assisted synchronous reluctance motor provided by the present application;

[0038] Figure 4 It is a control block diagram of the field weakening operation area of a permanent magnet assisted synchronous reluctance motor provided by the present application;

[0039] Figure 5 It is a target excitation current calculation block diagram of a permanent magnet assisted synchronous reluctance motor provided by the present application;

[0040] Figure 6 It is a structure block diagram of a control system of a permanent magnet assisted synchronous reluctance motor provided by the present application;

[0041] Figure 7 It is a structure block diagram of a control device of a permanent magnet assisted synchronous reluctance motor provided by the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The core of the present invention is to provide a control method and related components for a permanent magnet assisted synchronous reluctance motor, which can achieve stable control of the permanent magnet assisted synchronous reluctance motor while realizing maximum torque current ratio control in the constant torque operation region and high dynamic response control in the field weakening operation region, making the control of the motor more efficient and energy-saving.

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0044] Please refer to Figure 1 , Figure 1 which is a flowchart of a control method for a permanent magnet assisted synchronous reluctance motor provided in this application. The control method includes:

[0045] S1: Determine the target torque current of the permanent magnet assisted synchronous reluctance motor and adjust the torque current of the permanent magnet assisted synchronous reluctance motor to the target torque current;

[0046] S2: Determine the target field current when the permanent magnet assisted synchronous reluctance motor reaches the maximum torque current ratio;

[0047] S3: When the permanent magnet assisted synchronous reluctance motor is in the constant torque operation region, adjust the field current of the permanent magnet assisted synchronous reluctance motor to the target field current;

[0048] S4: When the permanent magnet assisted synchronous reluctance motor is in the field weakening operation region, determine the field current increment of the permanent magnet assisted synchronous reluctance motor, and adjust the field current according to the field current increment and the target field current to control the DC voltage in the steady-state equation of the permanent magnet assisted synchronous reluctance.

[0049] The control object of the control method provided in this application is a permanent magnet assisted synchronous reluctance motor. The permanent magnet assisted synchronous reluctance motor is a new type of motor that combines the advantages of permanent magnet synchronous motors and synchronous reluctance motors. However, there are many differences between the permanent magnet assisted synchronous reluctance motor and permanent magnet synchronous motors and synchronous reluctance motors, including but not limited to aspects such as structure, and the established steady-state voltage equation and electromagnetic torque equation, etc. Therefore, the control method for the permanent magnet assisted synchronous reluctance motor is also different from that of other motors. This application first analyzes the principle of the permanent magnet assisted synchronous reluctance motor (hereinafter referred to as the motor), and based on the proportion of the output voltage during the operation of the motor, proposes to use the quadrature-axis current as the excitation current to control the magnetic field of the motor by adjusting the excitation current; uses the direct-axis current as the torque current to control the output of the motor by adjusting the torque current, as well as the specific control strategy methods for the torque current and excitation current of the motor. Finally, it can achieve the maximum torque current ratio control and field weakening control of the motor, making the control of the motor more energy-efficient and improving the dynamic response performance of the motor during high-speed operation.

[0050] Specifically, the steady-state voltage equation of the permanent magnet assisted synchronous reluctance motor in the synchronous rotating coordinate system is as follows:

[0051]

[0052] Among them, u d is the direct-axis voltage of the motor, u q is the quadrature-axis voltage of the motor, i d is the direct-axis current, i q is the quadrature-axis current, R is the stator resistance, ω e is the synchronous angular frequency, L d is the direct-axis inductance, L q is the quadrature-axis inductance, ψ m is the permanent magnet flux linkage. The direct axis of the permanent magnet assisted synchronous reluctance motor is the direction with small magnetic reluctance of the motor, and this direction is 90 degrees ahead of the permanent magnet flux linkage direction. Therefore, in the steady-state voltage equation, the permanent magnet back electromotive force term is reflected in the equation corresponding to the direct-axis voltage.

[0053] The electromagnetic torque equation of the permanent magnet assisted synchronous reluctance motor is as follows:

[0054]

[0055] Among them, T e is the electromagnetic torque, N p is the number of pole pairs. The electromagnetic torque is the result of the interaction between current and magnetic field. It can be seen from the above electromagnetic torque equation that adjusting the quadrature-axis current can change the strength of the motor magnetic field, and adjusting the direct-axis current can change the magnitude of the motor output torque.

[0056] This application further considers that the structural characteristics of the permanent magnet assisted synchronous reluctance motor determine that its direct-axis inductance is much larger than its quadrature-axis inductance (about 4 times or more). When the motor runs at high speed, ω e L d i d will be the dominant term in the motor output voltage. If the direct-axis current of the motor is used as the excitation current, a relatively high output voltage is required to maintain the excitation current when the motor runs at high speed and no-load, resulting in the occupied adjustment space of the torque current and reducing the load-carrying capacity and speed regulation range of the motor. Therefore, this application uses the direct-axis current of the motor as the torque current and the quadrature-axis current of the motor as the excitation current.

[0057] On this basis, when this application adjusts and controls the torque current of the motor, first, the target torque current is determined according to the actual motor speed and the given motor speed of the motor, and then the torque current of the motor is adjusted to the target torque current. For example, after obtaining the actual motor speed and the given motor speed of the motor, the motor speed difference obtained by subtracting the actual motor speed from the given motor speed is input into the ASR (Automatic Speed Regulator), and the output of the speed regulator is used as the target torque current. Among them, the speed regulator can be any one of the proportional-integral link, proportional link, integral link, and proportional-integral-derivative link, and this application does not make special limitations on this.

[0058] When this application adjusts and controls the excitation current of the motor, it distinguishes between two situations where the motor is in the constant torque operation region and the motor is in the field weakening operation region. When the motor is in the constant torque operation region, this application takes achieving the maximum torque current ratio as the control target. Therefore, first, the target excitation current when the motor reaches the maximum torque current ratio is determined, and then when the motor is in the constant torque operation region, the excitation current of the motor is adjusted to the target excitation current. When the motor achieves the maximum torque current ratio, it can make the output voltage of the motor smaller and more energy-efficient on the premise of ensuring the working conditions.

[0059] When the motor is in the field weakening operation region, due to the limitation of the grid voltage, the output voltage capacity of the motor reaches the upper limit. If the voltage drop on the stator resistance is ignored, the total output voltage of the motor can be expressed as:

[0060]

[0061] where, u s is the total output voltage, u d is the direct-axis voltage of the motor, u q is the quadrature-axis voltage of the motor, i d is the direct-axis current, i q is the quadrature-axis current, L d is the direct-axis inductance, L qis the quadrature-axis inductance, and ψ m is the permanent magnet flux linkage. Since the direct-axis inductance of the motor is much larger than the quadrature-axis inductance, L d i d is the main part of the total output voltage of the motor. Considering from the perspective of control efficiency, reducing the direct-axis current is the fastest way to reduce the total output voltage. However, reducing the direct-axis current will cause a rapid drop in the output torque, resulting in fluctuations in the operating speed of the motor, and there is a problem of conflict with the torque current regulation. Based on the above considerations, in this application, when the motor is in the field-weakening operation region, the quadrature-axis current, that is, the field current, is selected to regulate the motor. While using the maximum torque current ratio control, this application combines the field current increment of the permanent magnet assisted synchronous reluctance motor to control the motor, so as to control the DC voltage in the steady-state equation of the permanent magnet assisted synchronous reluctance motor and reduce the back electromotive force ω e L q i q in the direct-axis voltage, thus ensuring a constant output voltage of the motor and completing the constant voltage field-weakening speed expansion function.

[0062] In summary, this application provides a control method for a permanent magnet assisted synchronous reluctance motor, which takes the direct-axis current of the permanent magnet assisted synchronous reluctance motor as the torque current and the quadrature-axis current of the motor as the field current; according to the actual motor speed and the given motor speed of the motor, the torque current is adjusted to the target torque current; the adjustment of the field current of the motor is divided into two parts: the constant torque operation region and the field-weakening operation region. When the motor is in the constant torque operation region, the field current is adjusted to the target field current value corresponding to the maximum torque current ratio, the target field current, to ensure a smaller output voltage of the motor without affecting the working conditions, making the control of the motor more efficient and energy-saving; when the motor is in the field-weakening operation region, the field current of the motor is adjusted based on the target field current and the field current increment, and the output voltage of the motor is ensured to be constant by reducing the field current, realizing a high dynamic response in the field-weakening operation region. Moreover, when using the control method provided by this application to control the motor, no additional hardware circuit and measuring instrument are required, which has strong engineering practical value.

[0063] Based on the above embodiments:

[0064] As an optional embodiment, determining the target field current when the permanent magnet assisted synchronous reluctance motor reaches the maximum torque current ratio includes:

[0065] Based on the maximum torque current ratio determination formula, determine the target field current; the maximum torque current ratio determination formula is:

[0066]

[0067] where is the target field current, ψm is the permanent magnet flux linkage, L d is the direct-axis inductance of the permanent magnet assisted synchronous reluctance motor, L q is the quadrature-axis inductance of the permanent magnet assisted synchronous reluctance motor, i d * is the target torque current.

[0068] Furthermore, the determination process of the maximum torque current ratio determination formula includes:

[0069] Based on the relationship between the stator current amplitude and the direct-axis current of the permanent magnet assisted synchronous reluctance motor, and the relationship between the stator current amplitude and the quadrature-axis current, determine the relationship between the torque and the current vector angle of the permanent magnet assisted synchronous reluctance motor;

[0070] Based on the partial derivative of the relationship between the torque and the current vector angle of the permanent magnet assisted synchronous reluctance motor with respect to the current vector angle, determine the maximum torque current ratio determination formula.

[0071] In order to achieve the control objective of the maximum torque current ratio when controlling the motor, in this embodiment, the target excitation current is determined by the maximum torque current ratio determination formula. First, the relationship between the stator current amplitude and the direct-axis current and the quadrature-axis current of the permanent magnet assisted synchronous reluctance motor is: where, i d is the direct-axis current, i q is the quadrature-axis current, I s is the stator current amplitude, β is the current vector angle. Substitute the above relationship between the stator current amplitude and the direct-axis current into the electromagnetic torque equation of the motor, and the relationship between the torque and the current vector angle of the motor is obtained as:

[0072] where, T e is the electromagnetic torque, N p is the number of pole pairs, L d is the direct-axis inductance, L q is the quadrature-axis inductance, I s is the stator current amplitude, β is the current vector angle, ψ m is the permanent magnet flux linkage. It can be seen that when the stator current amplitude is constant, different current vector angles correspond to different output torques. Determine the partial derivative of the above relationship between the torque and the current vector angle of the motor with respect to the current vector angle, and obtain:

[0073]

[0074] In order to obtain the maximum value of the electromagnetic torque, let The maximum torque current ratio determination formula is obtained as follows:

[0075]

[0076] wherein, is the target field current, ψ m is the permanent magnet flux linkage, L d is the direct-axis inductance of the permanent magnet assisted synchronous reluctance motor, L q is the quadrature-axis inductance of the permanent magnet assisted synchronous reluctance motor, i d * is the target torque current.

[0077] In addition, in order to ensure the reliable operation of the permanent magnet assisted synchronous reluctance motor without a position sensor, the field current needs to be maintained within a certain range. Therefore, in this embodiment, when the permanent magnet assisted synchronous reluctance motor is in the constant torque operation region and the target field current is less than the preset field current threshold, the preset field current threshold is used as the target to adjust the field current. The preset field current threshold can be the product of a preset adjustable gain value and the rated current of the permanent magnet assisted synchronous reluctance motor, wherein the preset adjustable gain value is a positive number less than 1.

[0078] In summary, when the permanent magnet assisted synchronous reluctance motor is in the constant torque operation region, the control strategy for the field current can be expressed as: where k is the preset adjustable gain value, i n is the rated current of the motor, and max represents the operation of taking the maximum value.

[0079] As an alternative embodiment, determining the field current increment of the permanent magnet assisted synchronous reluctance motor includes:

[0080] Inputting the voltage difference obtained by subtracting the actual output voltage from the maximum output voltage of the permanent magnet assisted synchronous reluctance motor into a voltage regulator, and determining the field current increment according to the output of the voltage regulator.

[0081] In this embodiment, when the motor is in the field weakening operation region, the voltage difference obtained by subtracting the actual output voltage from the maximum output voltage of the motor is input into the voltage regulator, and the field current increment is determined according to the output of the voltage regulator, so as to adjust the field current of the motor by combining the field current increment and the target field current. The voltage regulator can be any one of a proportional integral link, a proportional link, an integral link, and a proportional integral derivative link, and the present application does not make a special limitation on this. In order to reduce the back electromotive force ω e L q i q, to ensure that the output voltage of the motor is constant. In this embodiment, the value of the excitation current increment is negative, and the excitation current increment is also limited in this embodiment. Therefore, the specific implementation method for determining the excitation current increment in this embodiment is as follows: input the voltage difference obtained by subtracting the actual output voltage from the maximum output voltage of the permanent magnet assisted synchronous reluctance motor into the voltage regulator; when the output of the voltage regulator is negative and the output is not less than the preset output threshold, use the output of the voltage regulator as the excitation current increment; if the output of the voltage regulator is negative and the output is less than the preset output threshold, use the preset output as the excitation current increment; thus ensuring that the output voltage of the motor is constant, completing the constant voltage field weakening speed regulation function, and improving the reliability of the motor control.

[0082] As an alternative embodiment, it further includes:

[0083] When the permanent magnet assisted synchronous reluctance motor is in no-load operation and the rotor position of the permanent magnet assisted synchronous reluctance motor is determined by using a sensorless algorithm, increase the excitation current to a preset target excitation current.

[0084] Considering that when using a sensorless algorithm to obtain the rotor position of the permanent magnet assisted synchronous reluctance motor, the rotor flux linkage is required to complete the field orientation. However, when the motor is in no-load operation, the output current of the motor is relatively small, and it is easy to have the problem of field orientation failure due to too low signal-to-noise ratio. Therefore, in this embodiment, when the permanent magnet assisted synchronous reluctance motor is in no-load operation and the rotor position of the permanent magnet assisted synchronous reluctance motor is determined by using a sensorless algorithm, increase the excitation current to a preset target excitation current. The preset target excitation current can be k*i n (k < 1), which is used to establish the magnetic field, improve the current signal-to-noise ratio, and enhance the orientation accuracy of the sensorless algorithm.

[0085] Please refer to Figure 2 and Figure 3 , Figure 2 which is the main circuit topology diagram of a frequency converter driving a permanent magnet assisted synchronous reluctance motor provided by this application, Figure 3 and Figure 2 is the control block diagram of a permanent magnet assisted synchronous reluctance motor provided by this application. Figure 3 In * , the left circuit of the permanent magnet assisted synchronous reluctance motor is a frequency converter, and the frequency converter is used to drive the PMaSynRM (Permanent Magnet assisted Synchronous Reluctance Motor). Figure 3 In * f * is the given motor speed of the motor, f is the actual motor speed of the motor, and ASR, that is, the speed regulator, determines the target torque current i d* . In the loop for controlling the torque current of the motor, the difference between the target torque current \(i\) d * and the actual direct-axis current \(i\) of the motor d is input into the ACR (Automatic Current Regulator), and the ACR outputs the direct-axis voltage \(u\) of the motor d ; in the loop for controlling the field current of the motor, first, based on the target torque current \(i\) d * the target field current is obtained Figure 3 For the control block diagram of the " calculation" unit, please refer to Figure 5 , Figure 5 which is the target field current calculation block diagram of a permanent magnet assisted synchronous reluctance motor provided by this application. The difference between the target field current and the actual quadrature-axis current \(i\) of the motor q is input into the ACR, and the ACR outputs the quadrature-axis voltage \(u\) q . Then, the direct-axis voltage \(u\) d and the quadrature-axis voltage \(u\) q are subjected to coordinate transformation, from the dq axis to the αβ axis, and are input into the three-phase PWM inverter through SVPWM (Space Vector Pulse Width Modulation), and the three-phase currents (\(i\) u \(i\) v \(i\) w ) of the permanent magnet assisted synchronous reluctance motor are adjusted. The feedback loop of the current loop for controlling the torque current and the field current mainly performs two coordinate transformations on the three-phase currents again and feeds them back to the ACR, which will not be elaborated in this application. The feedback loop of the speed loop for controlling the speed of the motor is to obtain the rotor position of the motor (the method includes but is not limited to the method of determining the rotor position by using the sensorless method mentioned in this application), and then based on the rotor angle \(\theta\), the actual motor speed \(f\) of the motor is determined and compared with the given motor speed \(f\) * .

[0086] Figure 3 For the control block diagram of the field weakening controller in Figure 4 , Figure 4 which is the field weakening operation area control block diagram of a permanent magnet assisted synchronous reluctance motor provided by this application. Figure 4 Based on the direct-axis voltage \(u\) d and the quadrature-axis voltage \(u\) q after coordinate transformation, the voltages \(u\) α and \(u\) β are used to determine the actual output voltage \(u\) of the motors , subtract the actual output voltage u of the motor from the maximum output voltage u of the motor max and input the obtained voltage difference into a voltage regulator AVR (Automatic Voltage Regulation). Moreover, in this application, the limiter unit only uses the output of the voltage regulator as the excitation current increment △i when the output of the voltage regulator is negative s . And if the output of the voltage regulator is less than the preset output threshold, the preset output is used as the excitation current increment △i q . q .

[0087] In addition, it can be found from the above embodiments that in this application, the same loop structure is adopted when the motor is in the no-load operation state, the constant torque operation region, and the field-weakening operation region, without the need for switching, and the switching transition states of each operation state are good. Moreover, the control method provided in this application can be applied to both the motoring operation state and the generating operation state of the motor

[0088] Please refer to Figure 6 , Figure 6 , which is a structural block diagram of a control system for a permanent magnet assisted synchronous reluctance motor provided in this application. The control system for the permanent magnet assisted synchronous reluctance motor includes:

[0089] A torque current regulation unit 11, configured to determine a target torque current of the permanent magnet assisted synchronous reluctance motor and regulate the torque current of the permanent magnet assisted synchronous reluctance motor to the target torque current

[0090] A target field current determination unit 12, configured to determine a target field current when the permanent magnet assisted synchronous reluctance motor reaches the maximum torque current ratio

[0091] A first field current regulation unit 13, configured to regulate the field current of the permanent magnet assisted synchronous reluctance motor to the target field current when the permanent magnet assisted synchronous reluctance motor is in the constant torque operation region

[0092] A second field current regulation unit 14, configured to determine an excitation current increment of the permanent magnet assisted synchronous reluctance motor and regulate the field current according to the excitation current increment and the target field current to control the DC voltage in the steady-state equation of the permanent magnet assisted synchronous reluctance

[0093] For a detailed introduction to the control system for a permanent magnet assisted synchronous reluctance motor provided in this application, please refer to the embodiments of the control method for the permanent magnet assisted synchronous reluctance motor above, and this application will not elaborate here

[0094] Based on the above embodiments:

[0095] As an alternative embodiment, the target excitation current determination unit 12 is specifically configured to:

[0096] Determine the target excitation current based on the maximum torque current ratio determination formula; the maximum torque current ratio determination formula is:

[0097]

[0098] Wherein, is the target excitation current, ψ m is the permanent magnet flux linkage, L d is the direct-axis inductance of the permanent magnet assisted synchronous reluctance motor, L q is the quadrature-axis inductance of the permanent magnet assisted synchronous reluctance motor, i d * is the target torque current.

[0099] As an alternative embodiment, it further includes:

[0100] A target excitation current limiting unit, configured to adjust the excitation current of the permanent magnet assisted synchronous reluctance motor to a preset excitation current threshold when the permanent magnet assisted synchronous reluctance motor is in the constant torque operation region and it is determined that the target excitation current is less than the preset excitation current threshold.

[0101] As an alternative embodiment, it further includes:

[0102] An no-load excitation current control unit, configured to increase the excitation current to a preset target excitation current when the permanent magnet assisted synchronous reluctance motor is in the no-load operation state and the rotor position of the permanent magnet assisted synchronous reluctance motor is determined by using a sensorless algorithm.

[0103] As an alternative embodiment, the second excitation current regulation unit 14 includes:

[0104] An excitation current increment determination unit, configured to input the voltage difference obtained by subtracting the actual output voltage from the maximum output voltage of the permanent magnet assisted synchronous reluctance motor into a voltage regulator when the permanent magnet assisted synchronous reluctance motor is in the field weakening operation region, and determine the excitation current increment according to the output of the voltage regulator;

[0105] A second excitation current regulation subunit, configured to regulate the excitation current according to the excitation current increment and the target excitation current to control the DC voltage in the steady-state equation of the permanent magnet assisted synchronous reluctance.

[0106] As an alternative embodiment, the excitation current increment determination unit includes:

[0107] A first determination unit, configured to use the output of the voltage regulator as the excitation current increment when the output of the voltage regulator is negative and not less than a preset output threshold;

[0108] A second determination unit, configured to use a preset output as an excitation current increment when an output of a voltage regulator is negative and the output is less than a preset output threshold.

[0109] Please refer to Figure 7 , Figure 7 FIG. is a structural block diagram of a control device for a permanent magnet assisted synchronous reluctance motor provided by the present application. The control device for the permanent magnet assisted synchronous reluctance motor includes:

[0110] A memory 21, configured to store a computer program;

[0111] A processor 22, configured to implement the steps of any one of the above control methods for a permanent magnet assisted synchronous reluctance motor when executing the computer program.

[0112] For a detailed introduction to a control device for a permanent magnet assisted synchronous reluctance motor provided by the present application, please refer to the embodiments of the above control method for a permanent magnet assisted synchronous reluctance motor, and details are not described herein again.

[0113] The present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of any one of the above control methods for a permanent magnet assisted synchronous reluctance motor are implemented.

[0114] For a detailed introduction to a computer-readable storage medium provided by the present application, please refer to the embodiments of the above control method for a permanent magnet assisted synchronous reluctance motor, and details are not described herein again.

[0115] In the present specification, the embodiments are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0116] It should also be noted that in this specification, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0117] The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for a permanent magnet assisted synchronous reluctance motor, characterized in that Including: Determine the target torque current of the permanent magnet assisted synchronous reluctance motor, and adjust the torque current of the permanent magnet assisted synchronous reluctance motor to the target torque current; Determine the target excitation current when the permanent magnet assisted synchronous reluctance motor reaches the maximum torque current ratio; When the permanent magnet assisted synchronous reluctance motor is in the constant torque operation region, adjust the excitation current of the permanent magnet assisted synchronous reluctance motor to the target excitation current; When the permanent magnet assisted synchronous reluctance motor is in the field weakening operation region, determine the excitation current increment of the permanent magnet assisted synchronous reluctance motor, and adjust the excitation current according to the excitation current increment and the target excitation current to control the DC voltage in the steady-state equation of the permanent magnet assisted synchronous reluctance motor.

2. The control method of the permanent magnet assisted synchronous reluctance motor according to claim 1, characterized in that The determining the target excitation current when the permanent magnet assisted synchronous reluctance motor reaches the maximum torque current ratio includes: determining the target excitation current based on the maximum torque current ratio determination formula; the maximum torque current ratio determination formula is: Among them, is the target excitation current, ψ m is the permanent magnet flux linkage, L d is the direct-axis inductance of the permanent magnet assisted synchronous reluctance motor, L q is the quadrature-axis inductance of the permanent magnet assisted synchronous reluctance motor, i d * is the target torque current.

3. The control method of the permanent magnet assisted synchronous reluctance motor according to claim 2, wherein, The determination process of the maximum torque current ratio determination formula includes: Based on the relationship between the stator current amplitude of the permanent magnet assisted synchronous reluctance motor and the direct-axis current, and the relationship between the stator current amplitude and the quadrature-axis current, determine the relationship between the torque of the permanent magnet assisted synchronous reluctance motor and the current vector angle; Based on the partial derivative of the relationship between the torque of the permanent magnet assisted synchronous reluctance motor and the current vector angle with respect to the current vector angle, determine the maximum torque current ratio determination formula.

4. The control method of the permanent magnet assisted synchronous reluctance motor according to claim 1, characterized in that Also including: When the permanent magnet assisted synchronous reluctance motor is in the constant torque operation region and it is determined that the target excitation current is less than the preset excitation current threshold, adjust the excitation current of the permanent magnet assisted synchronous reluctance motor to the preset excitation current threshold.

5. The control method of the permanent magnet assisted synchronous reluctance motor according to claim 1, characterized in that, Also including: When the permanent magnet assisted synchronous reluctance motor is in the no-load operation state and the rotor position of the permanent magnet assisted synchronous reluctance motor is determined by using the sensorless algorithm, increase the excitation current to the preset target excitation current.

6. The control method of the permanent magnet assisted synchronous reluctance motor according to claim 1, characterized in that The determining the excitation current increment of the permanent magnet assisted synchronous reluctance motor includes: Input the voltage difference obtained by subtracting the actual output voltage from the maximum output voltage of the permanent magnet assisted synchronous reluctance motor into a voltage regulator, and determine the excitation current increment according to the output of the voltage regulator.

7. The control method of the permanent magnet assisted synchronous reluctance motor according to claim 6, characterized in that, The determining the excitation current increment according to the output of the voltage regulator includes: When the output of the voltage regulator is negative and the output is not less than the preset output threshold, use the output of the voltage regulator as the excitation current increment; When the output of the voltage regulator is negative and the output is less than the preset output threshold, use the preset output as the excitation current increment.

8. A control system for a permanent magnet assisted synchronous reluctance motor, characterized in that, Including: A torque current adjustment unit, configured to determine the target torque current of the permanent magnet assisted synchronous reluctance motor, and adjust the torque current of the permanent magnet assisted synchronous reluctance motor to the target torque current; A target excitation current determination unit, configured to determine the target excitation current when the permanent magnet assisted synchronous reluctance motor reaches the maximum torque current ratio; A first field current regulating unit, configured to regulate the field current of the permanent magnet assisted synchronous reluctance motor to the target field current when the permanent magnet assisted synchronous reluctance motor is in the constant torque operation region; A second field current regulating unit, configured to determine an increment of the field current of the permanent magnet assisted synchronous reluctance motor and regulate the field current according to the increment of the field current and the target field current when the permanent magnet assisted synchronous reluctance motor is in the field weakening operation region, so as to control the DC voltage in the steady-state equation of the permanent magnet assisted synchronous reluctance motor.

9. A control device for a permanent magnet assisted synchronous reluctance motor, characterized in that, Comprising: A memory, configured to store a computer program; A processor, configured to implement the steps of the control method of the permanent magnet assisted synchronous reluctance motor according to any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that, A computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the steps of the control method of the permanent magnet assisted synchronous reluctance motor according to any one of claims 1 to 7 are implemented.

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