Maximum torque current ratio control method and controller for interior permanent magnet synchronous motor

Abstract

The application relates to a maximum torque current ratio control method of an interior permanent magnet synchronous motor, a motor controller, a motor system and a computer program product. The method comprises the following steps: acquiring real-time parameters of the IPMSM (interior permanent magnet synchronous motor), and calculating MTPA real-time control parameters corresponding to MTPA (maximum torque per ampere) through a voltage steady-state equation. The method further comprises the following steps: determining MTPA trajectory errors based on the MTPA real-time control parameters, a direct-axis current and a quadrature-axis current of the IPMSM. In addition, the method further comprises the following steps: determining closed-loop control reference values of the direct-axis current and / or the quadrature-axis current corresponding to MTPA through closed-loop control based on the MTPA trajectory errors. In this way, only part of parameters can be used to determine the reference current meeting the conditions, so that the control performance of MTPA can be improved. In addition, the method can be applied to maximum torque voltage ratio (MTPV) control, and the difference is only that different trajectory equations are used.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of interior permanent magnet synchronous motor control, and more particularly, to a maximum torque current ratio control method for an interior permanent magnet synchronous motor, a motor controller, a motor system and a computer program product. BACKGROUND

[0002] Interior Permanent Magnet Synchronous Motor (IPMSM) refers to a type of permanent magnet motor whose rotor permanent magnet installation method is different from that of surface-mounted permanent magnet synchronous motor. The rotor of the IPMSM has a large difference in the magnetic resistance of the magnetic circuit in the direct axis and the cross axis of the permanent magnet, which is manifested in the inductance as the direct axis inductance (L d ) and the cross axis inductance (L q ) being unequal. After the stator of the IPMSM applies a current, the inequality of L d and L q will generate a reluctance torque, i.e., the electromagnetic torque of the IPMSM is the result of the combined action of the permanent magnet torque and the reluctance torque. The sizes of the two torques are related to the cross axis current (i q ) and the direct axis current (i d ), and under the condition that the total stator current I s is constant, different i d and i q allocation strategies will produce different electromagnetic torques. By adjusting i d and i q , the motor can generate the maximum electromagnetic torque, which is the problem to be solved by the Maximum Torque Per Ampare (MTPA) control. Similarly, for the reluctance type IPMSM, the maximum voltage utilization problem needs to be solved in deep field weakening control under voltage limitation, and the Maximum Torque per Volt (MTPV) control also needs to reasonably allocate id and iq.

[0003] The traditional method for determining the MTPA and MTPV control currents of the IPMSM generally adopts direct motor parameter calculation, high-frequency signal injection, virtual signal injection, etc., all of which have their own problems, some have large errors after the motor parameters change, some are complex to calculate, and some have torque pulsation, etc. SUMMARY

[0004] Embodiments of the present application provide a maximum torque per ampere (MTPA) control method, a motor controller, a motor system and a computer program product for an interior permanent magnet synchronous motor (IPMSM). In embodiments of the present application, parameters required for MTPA control can be calculated by using a motor steady-state voltage equation based on real-time parameters and state variables of the IPMSM, so as to obtain a more accurate MTPA trajectory error. The direct-axis reference current and the quadrature-axis reference current of the motor are dynamically adjusted according to the MTPA trajectory error. In this way, the conditions that can be provided by the motor system can be fully utilized from the perspective of the motor system as a whole, and the reference current that meets the conditions can be determined by using only part of the parameters, so as to improve the control performance of the MTPA. In addition, no additional signal injection is required, and no torque fluctuation or noise is caused; nor is there a complex modulation and demodulation process, i.e., no large amount of operations such as modulation and demodulation, so as to simplify the implementation process and improve the calculation efficiency.

[0005] In a first aspect of the present application, a MTPA control method for an IPMSM is provided. The method comprises calculating MTPA real-time control parameters corresponding to MTPA by using a voltage steady-state equation based on real-time acquisition parameters of the IPMSM. The method further comprises determining a MTPA trajectory error based on the MTPA real-time control parameters, a direct-axis current and a quadrature-axis current of the IPMSM. In addition, the method further comprises determining a closed-loop control reference value of the direct-axis current and / or the quadrature-axis current corresponding to MTPA by closed-loop control based on the MTPA trajectory error.

[0006] In a second aspect of the present application, a MTPA control device for an IPMSM is provided. The device comprises a calculation unit configured to calculate MTPA real-time control parameters corresponding to MTPA by using a voltage steady-state equation based on real-time acquisition parameters of the IPMSM. The device further comprises a trajectory error determination unit configured to determine a MTPA trajectory error based on the MTPA real-time control parameters, a direct-axis current and a quadrature-axis current of the IPMSM. The device further comprises a closed-loop control unit configured to determine a closed-loop control reference value of the direct-axis current and / or the quadrature-axis current corresponding to MTPA by closed-loop control based on the MTPA trajectory error.

[0007] In a third aspect of the present application, a motor controller is provided. The motor controller comprises at least one processor; and a memory coupled to the at least one processor and having stored therein instructions that, when executed by the at least one processor, cause the motor controller to implement the method provided by the first aspect of the present application.

[0008] In a fourth aspect of the present application, a motor system is provided. The motor system comprises a permanent magnet synchronous motor and the motor controller provided by the third aspect of the present application.

[0009] In a fifth aspect of the present application, a computer readable storage medium is provided. The computer readable storage medium has stored thereon computer-executable instructions, wherein the computer-executable instructions, when executed by a processor, implement the method provided by the first aspect of the present application.

[0010] According to a sixth aspect of the present application, a computer program product is provided, comprising machine executable instructions that, when executed by a machine, cause the machine to perform the method provided by the first aspect of the present application.

[0011] It is to be understood that the description of the summary section is not intended to identify key or essential features of embodiments of the application, nor is it intended to limit the scope of the application. Other BRIEF DESCRIPTION OF DRAWINGS

[0012] The above and other features, aspects and advantages of embodiments of the present application will become more apparent from the following description of the embodiments when taken in conjunction with the accompanying drawings. In the drawings:

[0013] Figure 1 A schematic diagram showing an example environment in which embodiments of the present application can be implemented is shown;

[0014] Figure 2 A flow chart showing a maximum torque current ratio control method for an interior permanent magnet synchronous motor according to some embodiments of the present application is shown;

[0015] Figure 3 A trajectory diagram showing a maximum torque current ratio according to some embodiments of the present application is shown;

[0016] Figure 4 A trajectory diagram showing a maximum torque voltage ratio according to some embodiments of the present application is shown;

[0017] Figure 5 A diagram showing MTPA control and MTPV control of a motor drive system according to some embodiments of the present application is shown;

[0018] Figure 6 A diagram showing MTPA trajectory tracking according to some embodiments of the present application is shown;

[0019] Figure 7 A diagram showing MTPV trajectory tracking according to some embodiments of the present application is shown;

[0020] Figure 8 A block diagram showing a maximum torque current ratio control apparatus for an interior permanent magnet synchronous motor according to some embodiments of the present application is shown; and

[0021] Figure 9 A block diagram of a device that can implement several embodiments of the present invention is shown. Detailed Implementation

[0022] Embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While some embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the invention. It should be understood that the accompanying drawings and embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the invention.

[0023] In the description of embodiments of the present invention, the term "comprising" and similar terms should be understood as open-ended inclusion, i.e., "including but not limited to". The term "based on" should be understood as "at least partially based on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0024] As mentioned above, in a permanent magnet motor, the direction of the permanent magnet's magnetic field is defined as the direct axis (d-axis), and the direction perpendicular to the permanent magnet's magnetic field is defined as the quadrature axis (q-axis). In an integrated permanent magnet synchronous motor: in the direct axis state, the magnetic circuit passes through the permanent magnet; while in the quadrature axis state, the magnetic circuit only contains the iron core. This results in a difference in stator inductance between the two states. Due to the inconsistency between its direct and quadrature axis inductances, its output torque consists of two parts: one is the permanent magnet torque generated by the interaction of the permanent magnets, and the other is the reluctance torque caused by the unevenness of the rotor's magnetic reluctance. The magnitudes of both torques are related to the quadrature axis current and the direct axis current. Under the condition that the total stator current remains constant, different direct axis currents and quadrature axis currents will produce different electromagnetic torques. In motor control and drive systems, maximizing the motor's output torque is crucial, thus proposing control requirements for the maximum torque-to-current ratio and the maximum torque-to-voltage ratio.

[0025] There are many types of MTPA control methods, which can be divided into three categories based on whether or not motor parameters are used. One category relies entirely on motor parameters, such as the direct parameter calculation method. Another category does not require any motor parameters, such as the search method and the high-frequency signal injection method. The third category relies on some parameters, such as the virtual signal injection method. Methods that rely entirely on motor parameters suffer from increased control error after parameter changes. Methods that do not rely on motor parameters generally suffer from torque ripple problems. Furthermore, the virtual high-frequency signal injection method relies on some motor parameters, has a complex algorithm, and consumes significant processing time and space.

[0026] Based on this, embodiments of the present invention provide a method for maximum torque-to-current ratio control of an embedded permanent magnet synchronous motor. In embodiments of the present invention, some real-time motor parameters and corresponding state variables of the operating state can be obtained. Based on these real-time motor parameters and state variables, some unknown real-time parameters required for MTPA and MTPV control, such as direct-axis inductance, quadrature-axis inductance, and flux linkage, can be determined. Based on these unknown real-time parameters, direct-axis current, and quadrature-axis current, the MTPA trajectory error of the motor can be determined. Based on the MTPA trajectory error, through error closed-loop control, the direct-axis reference current and / or quadrature-axis reference current of MTPA and MTPV are determined.

[0027] In this way, considering the entire motor system, the available conditions are fully utilized. The reference current that meets the requirements can be determined using only a subset of parameters, thereby improving the control performance of MTPA and MTPV. Furthermore, no additional signal injection is needed, preventing torque fluctuations or noise; and there is no complex modulation / demodulation process, eliminating the need for extensive computations such as modulation and demodulation, thus simplifying the implementation and improving computational efficiency.

[0028] Figure 1 A schematic diagram of an example environment 100 in which various embodiments of the present invention may be implemented is shown. For example... Figure 1 As shown, in environment 100, the motor system includes a built-in permanent magnet synchronous motor 102 and a motor controller 104. The motor controller 104 can be a controller with computing capabilities, such as a digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), etc. In some embodiments, this motor system can be applied to any application scenario requiring a motor to provide power, such as, but not limited to, industrial automation, industrial robots, electric vehicles, CNC machine tools, aerospace, home appliances, etc.

[0029] like Figure 1 As shown, during the operation of motor 102, its parameters can be acquired in real time. For example, real-time parameters of motor 102 can be acquired through sensors or other devices. These real-time parameters may include the direct-axis current of motor 102. i d quadrature axis current i q Direct-axis voltage u d and quadrature axis voltage uq Stator Temperature t s The motor controller 104 can calculate the real-time control parameters required for MTPA and MTPV control through the steady-state voltage equation after obtaining the real-time acquisition parameters of the motor 102. For example, the parameters required for MTPA and MTPV control can be calculated by the MTPA real-time parameter calculation module 108 (or the MTPV real-time parameter calculation module), which can include but is not limited to flux linkage Ψ f ( t ), direct-axis inductance L d(t) and quadrature-axis inductance L q(t) , etc. After determining the parameters required for MTPA and MTPV control, the MTPA trajectory error calculation module 110 (or the MTPV trajectory error calculation module) of the motor controller 104 can determine the corresponding MTPA trajectory error (or MTPV trajectory error) based on part of the real-time acquisition parameters such as direct-axis current and quadrature-axis current, and the calculated real-time control parameters. The trajectory error tracking module 106 of the motor controller 104 can realize MTPA trajectory tracking control of the motor 102, which is essentially a closed-loop control process of current feedback→error calculation→closed-loop adjustment→reference current output, and the core goal is to dynamically correct the direct-axis reference current and / or the quadrature-axis reference current to make the motor always run in the optimal state of minimum current at the output target torque. For example, the trajectory error tracking module 106 can realize automatic tracking of the maximum torque current ratio trajectory by using a trajectory error regulator. The trajectory error regulator in the trajectory error tracking module 106 can be a proportional integral regulator, a model predictive control regulator, or other regulators, and the application does not limit the form of the trajectory error regulator. Taking the proportional integral regulator as an example, the MTPA trajectory error can be taken as the feedback input of the proportional integral regulator, and the proportional integral regulator outputs the direct-axis reference current or the quadrature-axis reference current. Based on the direct-axis reference current or the quadrature-axis reference current, the motor 102 is driven to run through the current control and space vector pulse width modulation (SVPWM) module 112. In this way, automatic tracking of the MTPA and MTPV trajectories can be realized through closed-loop control. For example, if the trajectory error is greater than a preset value, it indicates that the current deviates far from the MTPA trajectory (such as the positive error caused by the small direct-axis current), and the current adjustment amount needs to be increased (such as increasing the negative direct-axis reference current), so as to quickly reduce the deviation.

[0030] Furthermore, when motor 102 operates at high speed, the back electromotive force (EMF) increases with increasing speed. When the back EMF reaches a certain level, the speed cannot be further increased due to the limitation on the maximum voltage provided by motor controller 104. Therefore, to further increase the speed, field weakening control can be employed. This involves adjusting the direct-axis current to a negative value to weaken the air gap magnetic field, thereby reducing the back EMF and ensuring that the motor terminal voltage does not exceed the maximum voltage output by the controller. In the deep field weakening control region, prioritizing system stability and improving voltage utilization, MTPV control is a good choice. Similar to MTPA control, MTPV control can also be implemented by referring to the automatic trajectory tracking method of MTPA, which will not be elaborated further in this application.

[0031] Figure 2 A flowchart of a maximum torque-to-current ratio control method 200 for an embedded permanent magnet synchronous motor according to some embodiments of the present invention is shown. Method 200 can be derived from... Figure 1 The motor controller 104 executes this. For example... Figure 2 As shown in block 202, method 200 may include real-time acquisition parameters based on IPMSM, and calculate the real-time control parameters of MTPA corresponding to MTPA through voltage steady-state equation.

[0032] In some embodiments, real-time acquired parameters may include the direct-axis current and quadrature-axis current of the built-in permanent magnet synchronous motor. The direct-axis current and quadrature-axis current can be obtained by transforming the three-phase stator current. For example, the three-phase stator current of the motor can be acquired using current sensors (e.g., Hall effect sensors, sampling resistors + operational amplifiers, etc.). Based on this, the three-phase stator current can be converted into current components in a two-phase stationary αβ coordinate system, such as i... α and i βThe current components in the two-phase stationary αβ coordinate system can be converted to the coordinate system (dq coordinate system) rotating synchronously with the rotor magnetic field by Park transformation, so as to obtain the direct-axis current and the quadrature-axis current. In the conversion process, the current components need to be converted into the direct-axis current and the quadrature-axis current in the dq coordinate system according to the electrical angle of the rotor. In some embodiments, the electrical angle of the rotor can be determined by using an encoder (such as an optical encoder, a magnetic encoder) or a rotor position sensor, a position observer. In other embodiments, the real-time collected parameters can further include the direct-axis voltage and the quadrature-axis voltage of the IPMSM. For example, the three-phase stator voltage of the motor can be collected by a voltage sensor, and the direct-axis voltage and the quadrature-axis voltage can be determined based on Clark transformation and Park transformation. That is, the IPMSM can include three-phase stator voltage and / or three-phase stator current. On this basis, the parameters of the motor such as direct-axis inductance, quadrature-axis inductance or flux linkage can be estimated based on the voltage steady-state equation. The estimated motor parameters can be used as real-time control parameters required for MTPA or MTPV control. In some other embodiments, the real-time collected parameters can further include the stator temperature or the temperature of other motor components, which is not limited in the present application.

[0033] At block 204, the method 200 can include determining a MTPA locus error based on the MTPA real-time control parameter, the direct-axis current and the quadrature-axis current of the IPMSM. The torque of the IPMSM is generated by the permanent magnet torque and the reluctance torque. For the same output torque, different combinations of the direct-axis current and the quadrature-axis current will generate different stator current amplitudes. The control objective of MTPA is to minimize the required stator current amplitude of the motor while meeting the load torque requirement. The locus corresponding to the maximum torque current ratio is a curve formed by all the combinations of the quadrature-axis current and the direct-axis current satisfying the MTPA condition in the dq coordinate system plane. When the motor operates on this curve, for each torque value, the current amplitude is the smallest. It can be understood that the direct-axis current and the quadrature-axis current can uniquely define the current working point of the motor in the dq coordinate system. By comparing the position relationship between the current working point of the motor and the ideal MTPA locus, an error value representing the deviation degree can be determined, that is, the locus error is determined. In some embodiments, if the locus error is greater than 0, it indicates that the current direct-axis current is too small; if the locus error is less than 0, it indicates that the current direct-axis current is too large.

[0034] At block 206, the method 200 can include determining, by the closed-loop control, a closed-loop control reference value of the direct-axis current and / or the quadrature-axis current corresponding to the MTPA based on the MTPA trajectory error. The closed-loop control reference value can be a direct-axis reference current or a quadrature-axis reference current. Wherein, the direct-axis reference current of the motor is a desired current value of the motor on the direct axis. Similarly, the quadrature-axis reference current is a desired current value of the motor on the quadrature axis. The actual current (direct-axis current and quadrature-axis current) of the motor is adjusted by the current loop controller to track the reference current (direct-axis reference current and quadrature-axis reference current), so as to control the torque and magnetic field of the motor. That is, in order to make the motor efficiently output a given torque, thereby achieving efficient control of the motor, the motor controller can make the operating point of the motor automatically track the ideal trajectory of the maximum torque current ratio. That is, by calculating the trajectory error between the current operating point and the trajectory of the maximum torque current ratio in real time, the direct-axis current or the quadrature-axis current is adjusted to make the operating point approach the trajectory of the maximum torque current ratio, thereby realizing the control strategy of automatic tracking of the trajectory.

[0035] In some embodiments, different motor drive systems can have different system configurations. For example, the motor drive system 1 can be provided with various sensors such as a rotor position sensor (encoder, etc.) and a temperature sensor (for example, a temperature sensor near the stator); the motor drive system 2 can be provided with a temperature sensor and not provided with a rotor position sensor, which can be a system with online identification of the permanent magnet flux linkage; the motor drive system 3 can be provided with a motor parameter observer, which can be a system capable of online observation of the direct-axis inductance and the quadrature-axis inductance; the motor drive system 4 can be a system without any temperature detection or motor parameter estimation. Different motor drive systems can determine the required motor parameters in different ways. For example, the required motor parameters such as the direct-axis inductance, the quadrature-axis inductance, the flux linkage, etc. can be updated in real time in different ways. In some embodiments, the flux linkage of the motor can be obtained by real-time observation. In other embodiments, in order to avoid measurement noise and parameter error, the flux linkage of the motor can also be calculated based on the measurable temperature.

[0036] In actual applications, the resistance value of the stator winding (copper or aluminum) increases linearly with the increase of temperature, and there is a corresponding relationship between the resistance value and the temperature. Based on this, for the motor drive system 1, the real-time control parameters required for MTPA or MTPV control such as the flux linkage or the quadrature-axis inductance, the direct-axis inductance, etc. can be determined based on the acquired motor parameters. For example, the current stator resistance value can be calculated based on the measured stator temperature and the material (generally aluminum or copper) of the stator winding and the nominal value of the stator resistance at 25 degrees environment. For example, the stator resistance value can be calculated by using the following formula (1) R s t ​​

[0037] (1)

[0038] wherein, α r is the temperature coefficient of resistance of the stator winding material. When the stator winding material is copper wire (Cu), the temperature coefficient of resistance can be 0.00385 / K; when the stator winding material is aluminum wire (AL), the temperature coefficient of resistance can be 0.00400 / K.

[0039] The rotor temperature can be estimated according to the stator temperature and the temperature difference between the stator temperature and the rotor temperature. Wherein, the temperature difference ΔT between the stator and the rotor can be determined by the following formula (1): t s-r ( i s ,t ) can be determined by experience values or functions related to the motor thermal model, related to the motor heat dissipation structure, current and time. In some examples, the temperature difference can be obtained by querying a preset two-dimensional table, or can be calculated by a thermal inertia model. For example, the rotor temperature can be determined by using the following formula (2): t r :

[0040] (2)

[0041] After determining the rotor temperature, the permanent magnet flux linkage can be estimated according to the rotor temperature and the permanent magnet flux linkage value of the motor at 25 degrees. For example, the flux linkage of the motor can be determined by using the following formula (3): Ψ f ( t ):

[0042] (3)

[0043] wherein, Ψ f-25 ( t ) is the flux linkage of the motor at 25 degrees. α Br is the temperature coefficient of the residual magnetism of the permanent magnet. It is related to the permanent magnet material, for example, when the permanent magnet material is neodymium iron boron, α Br the coefficient (NdFeB) can be -0.11% / k; when the permanent magnet material is ferrite (Fe2O3), α Br the coefficient can be -0.18% / K.

[0044] On this basis, the direct-axis inductance and the quadrature-axis inductance of the motor can be determined by using the steady-state equation of the motor and the estimated stator resistance and the flux linkage of the motor. For example, the direct-axis inductance can be determined by using the following formula (4):L d ( t ) and quadrature axis inductance L q ( t ), wherein is the motor speed estimated or measured by the drive system:

[0045] (4)

[0046] That is, in the case that the motor drive system is provided with a temperature sensor, the direct axis inductance and the quadrature axis inductance of the motor can be estimated based on the stator temperature collected by the motor steady-state equation. In other embodiments, in the case that the motor drive system is not provided with a position sensor, i.e. for the motor drive system 2, the rotor temperature can be determined based on an online identification algorithm to determine the flux of the motor, and then the direct axis inductance and the quadrature axis inductance of the motor are determined. For example, the rotor temperature can be calculated by using the following equation (5) t r :

[0047] (5)

[0048] Based on this, the stator temperature can be determined according to the determined rotor temperature and the temperature difference between the stator and the rotor. For example, the stator temperature can be determined by using t s According to the stator temperature and the stator resistance value at 25 degrees of the environment, the stator resistance can be determined. For example, the stator resistance can be determined by using the following equation (6) R s ( t ):

[0049] (6)

[0050] In some embodiments, based on the determined stator resistance, the real-time estimated permanent magnet flux, the direct axis inductance and the quadrature axis inductance of the motor are determined by using the motor steady-state voltage equation. For example, referring to equation (4), the direct axis inductance and the quadrature axis inductance of the motor can be determined by using the following equation (7):

[0051] (7)

[0052] Similarly, in the case that the motor drive system can estimate the direct axis inductance and the quadrature axis inductance in real time online, i.e. for the motor drive system 3, the permanent magnet flux can be determined by using the observed direct axis inductance and the quadrature axis inductance. Based on the real-time estimated motor parameters such as the permanent magnet flux, the direct axis inductance and the quadrature axis inductance, the trajectory error corresponding to the maximum torque current ratio or the maximum torque voltage ratio is determined. For example, the permanent magnet flux of the motor can be calculated by using the following equation (8):​

[0053] (8)

[0054] In other embodiments, where the motor drive system lacks additional sensors or online identification algorithms, the required motor parameters can be determined using nominal parameters and voltage equations. For example, the nominal resistance of the motor drive system at 25°C can be directly utilized. R s-25 Nominal direct-axis inductance L d-25 Based on the voltage equation, the quadrature-axis inductance and permanent magnet flux linkage can be determined in real time. For example, the quadrature-axis inductance and permanent magnet flux linkage can be determined using the following equation (9):

[0055] (9)

[0056] In this way, different parameter update strategies can be adopted according to different system configurations (sensors and identification capabilities), thereby achieving adaptive control under different cost and control accuracy requirements, and improving the robustness and accuracy of MTPA / MTPV control. In other words, the motor drive system does not use fixed motor parameters, but calculates and updates key motor parameters in real time based on the system hardware capabilities, thus making MTPA / MTPV trajectory tracking more accurate.

[0057] Figure 3 A schematic diagram of the trajectory for the maximum torque-current ratio provided according to some embodiments of the present invention is shown. For example... Figure 3 As shown, a two-dimensional coordinate system is constructed with the direct-axis current as the horizontal axis and the quadrature-axis current as the vertical axis. All points (i) on the same constant torque curve (or constant torque curve) are considered. d i q The electromagnetic torque produced by all points on the same circle (which can be called the current-limiting circle) is exactly the same. The total current magnitude I is the same at all points on the same circle. s They are the same. For any constant torque line, the optimal point of MTPA can be determined based on the intersection of the constant torque line and the current limiting circle (i.e., the point of tangency between the constant torque line and the current limiting circle), which is the operating point where the stator current amplitude is minimized under the current torque.

[0058] In some embodiments, the MTPA trajectory is the current vector trajectory that maximizes the output torque. The MTPV trajectory, on the other hand, is the current vector trajectory that maximizes the output torque under voltage limitations. By adjusting the values ​​of id and iq, i.e., the direction of the current vector, the motor can output maximum torque under certain voltage limitations. The maximum torque-to-voltage ratio curve refers to the relationship between the maximum torque that the motor can provide at different speeds within the motor's operating range and the corresponding voltage.

[0059] Figure 4 A schematic diagram of the trajectory for the maximum torque-voltage ratio provided according to some embodiments of the present invention is shown. For example... Figure 4 As shown, a two-dimensional coordinate system can be constructed with the direct-axis current as the horizontal axis and the quadrature-axis current as the vertical axis. All points (i) on the same constant torque curve (or constant torque curve) d i q The electromagnetic torque produced by all points on the same circle (which can be called the voltage limit circle) is exactly the same. The total voltage magnitude is the same at all points on the same circle. For any line of constant torque, the optimal point of the MTPV can be determined based on the intersection of the line of constant torque and the voltage limit circle (the point of tangency between the voltage limit circle and a certain line of constant torque). Based on this, the MTPV trajectory can be determined by connecting the optimal points of the MTPV for each line of constant torque.

[0060] Figure 5 Schematic diagrams of MTPA control and MTPV control of a motor drive system according to some embodiments of the present invention are shown. Figure 5 As shown, in the motor drive system 500 (in this motor drive system, the motor is a built-in permanent magnet synchronous motor), the three-phase current i of the motor is collected. a i b and i c The Clark converter module can convert the three-phase current i of the motor a i b and i c Transformed into a two-phase orthogonal coordinate system αβ, current i α and i β The Park transformation module will transform i α and i β Transforming to the dq coordinate system oriented by the rotor permanent magnet, the direct-axis current i is obtained. d and cross-axis current i q It can be understood that the direct-axis current and quadrature-axis current here are the real-time current values ​​of the motor. Direct-axis current i d and cross-axis current i q Input can be sent to the parameter and status measurement and identification module. This module can then calculate other required motor parameters based on the measured motor parameters. For example, in a motor drive system with rotor position detection, the speed signal can be directly measured, and the parameter and status measurement and identification module can identify the direct-axis inductance L based on the measured speed signal. d and cross-axis inductance L q .

[0061] like Figure 5 As shown, the stator voltage equation of the motor drive system 500 in the two-phase dq coordinate system with rotor permanent magnet orientation is as follows (10):

[0062] (10)

[0063] wherein, u d , u q , i d , i q and L d , L q are the d-axis and q-axis voltages, currents and inductances, respectively; ω r is the angular frequency of the rotor, R s is the stator resistance, Ψ f is the permanent magnet flux linkage.

[0064] When the motor is in steady state, the current differential term can be ignored, and the stator voltage equation can be simplified as the following formula (11):

[0065] (11)

[0066] In some embodiments, in the MTPV control scenario under high-speed deep field weakening, the resistance voltage drop can be ignored, and the stator voltage equation can be further simplified as the following formula (12):

[0067] (12)

[0068] In some embodiments, the torque equation of the IPMSM drive system at steady state is represented as the following formula (13):

[0069] (13)

[0070] wherein, T e is the electromagnetic torque, T L is the load torque. Wherein, when the motor is in steady state T e is equal to T L . In addition, n p is the number of rotor pole pairs.

[0071] In the two-phase dq coordinates, the current amplitude i s and the voltage amplitude u s The relationship between the dq-axis current and voltage is the following formula (14):

[0072] (14)

[0073] For convenience of description, the solving method of MTPA and MTPV is unified, and the MTPA and MTPV control trajectory is solved by using the Lagrange extreme value equation. In another aspect, the MTPA can be equivalently described as using the minimum current i s that meets the load requirement, and the MTPV can be described as using the minimum voltage u s that meets the load requirement. In some embodiments, the optimization method of MTPA control can be represented as the following formula (15):

[0074] (15)

[0075] On this basis, the constructed MTPA Lagrange extreme value equation is as the following formula (16):

[0076] (16)

[0077] Based on this, the trajectory equation of MTPA obtained by solving is where . It can be known that the condition for the MTPA trajectory equation to have a solution is .

[0078] Similarly, the optimization method of MTPV control can be represented as the following formula (17):

[0079] (17)

[0080] On this basis, the constructed MTPV Lagrange extreme value equation can be:

[0081]

[0082] In some embodiments, the trajectory equation of MTPV obtained by solving based on the above Lagrange extreme value equation is where . The condition for the MTPV trajectory equation to have a solution can be In some embodiments, the trajectory calculation and trajectory error calculation of MTPA and MTPV need to rely on motor parameters such as motor flux, direct-axis inductance or quadrature-axis inductance. In the case of fixed motor parameters, in order to save calculation cost, the nominal parameters of the motor at 25° can be directly used; in the scene of high temperature or high load, the motor flux and the direct-axis inductance and the quadrature-axis inductance can be determined in real time through temperature sensors or parameter identification, so as to improve the accuracy of the trajectory error.

[0083] In some embodiments, the MTPA trajectory error function can be constructed according to the MTPA control trajectory equation, which can be an error function of the MTPA control trajectory equation and an ideal trajectory equation ΔTr A , ΔTr A The following formula (18) can be used to determine:

[0084] (18)

[0085] Similarly, the MTPV trajectory error function can also be constructed according to the MTPV control trajectory equation as the following formula (19):

[0086] (19)

[0087] On this basis, the MTPA trajectory error function and the MTPV trajectory error function can be input to a proportional integral (PI) regulator of a motor drive system. For example, the proportional integral regulator can use the following formula (20) to determine the direct-axis current reference value i d-MTPA (MTPA control corresponding direct-axis reference current):

[0088] (20)

[0089] wherein, k p-MTPA and k i-MTPA are the proportional coefficient and the integral coefficient of the proportional integral regulator under the MTPA control scenario, respectively.

[0090] Similarly, under the MTPV control scenario, the proportional integral regulator can use the following formula (21) to determine the direct-axis reference current i p-MTPA (MTPV control corresponding direct-axis reference current):

[0091] (21)

[0092] wherein, k p-MTPV and k i-MTPV are the proportional coefficient and the integral coefficient of the proportional integral regulator under the MTPV control scenario, respectively.

[0093] In some embodiments, to ensure stable motor control, the reference current can be limited. For example, the range of the direct-axis reference current can be determined based on the solvability of the trajectory (to avoid demagnetization of the permanent magnet) and hardware safety conditions (such as the maximum permissible direct-axis current of the motor or the maximum output current of the inverter). For example, the range of the direct-axis reference current can be determined using the following formula:

[0094]

[0095] like Figure 5 As shown, after determining the direct-axis reference current, the motor drive system 500 can use some motor parameters provided by the parameter and state measurement and estimation module, combined with the voltage equation, to calculate and update some control parameters required for MTPA and MTPV trajectory tracking in real time. Ψ f (t), Ld(t) or Lq(t) and if1 and if2. In some embodiments, during the current control cycle (or sampling cycle), the direct-axis voltage and quadrature-axis voltage are converted into inverter switching signals by space vector pulse width modulation (SVPWM) to drive the motor; at the same time, the direct-axis current and quadrature-axis current are re-acquired in the next control cycle, and the above process is repeated to achieve continuous tracking of the MTPA trajectory.

[0096] Figure 6 A schematic diagram of MTPA trajectory tracking provided according to some embodiments of the present invention is shown. For example... Figure 6 As shown, in the motor drive system 600, closed-loop regulation of MTPA control can be achieved, ensuring that the direct-axis current and quadrature-axis current of the motor always track the optimal MTPA trajectory, thus achieving efficient motor operation. Based on the acquired direct-axis current and quadrature-axis current of the built-in permanent magnet synchronous motor, the MTPA trajectory error can be determined. The adjustment objective of the PI controller can be to adjust the direct-axis current so that the MTPA trajectory error is the same as a preset value (e.g., 0). For example, the PI controller can convert the trajectory error into a direct-axis reference current. It is understood that due to hardware current limitations or stability range limitations of the motor and inverter, the direct-axis reference current output by the PI controller needs to be limited to avoid overcurrent or demagnetization of the permanent magnet. Afterwards, the direct-axis reference current can be converted into a motor drive signal to complete the closed-loop regulation of MTPA control. After the motor starts running, the three-phase current is re-acquired and converted into direct-axis and quadrature-axis currents, which are then input into the trajectory error calculation module, forming a complete closed loop of error → regulation → execution → feedback. Similarly, as... Figure 7 As shown, closed-loop regulation of MTPV control can also be achieved in the motor drive system 700. That is, closed-loop control enables the motor current combination (direct-axis current, quadrature-axis current) to track the optimal MTPV trajectory, avoiding inverter voltage saturation, thereby extending the high-speed operating range of the motor.

[0097] Figure 8 A block diagram of a maximum torque per current control device for an interior permanent magnet synchronous motor is shown in accordance with some embodiments of the present application. The device 800 includes a calculation unit 802 configured to calculate, based on real-time acquisition parameters of the IPMSM, a MTPA real-time control parameter corresponding to the MTPA by a voltage steady-state equation. The device 800 further includes a trajectory error determination unit 804 configured to determine a MTPA trajectory error based on the MTPA real-time control parameter, a direct-axis current and a quadrature-axis current of the IPMSM. The device 800 further includes a closed-loop control unit 806 configured to determine, based on the MTPA trajectory error, a closed-loop control reference value of the direct-axis current and / or the quadrature-axis current corresponding to the MTPA by a closed-loop control.

[0098] It can be appreciated that with the device 800 of the present application, at least one of the many advantages as can be achieved by the method or process described above can be achieved. For example, the device 800 can reduce copper loss and improve driving efficiency of the motor driving system.

[0099] In some embodiments, the MTPA real-time control parameter includes an equivalent excitation current of the IPMSM, and the trajectory error determination unit 804 is further configured to determine the equivalent excitation current based on a flux of the IPMSM, a direct-axis inductance and a quadrature-axis inductance of the IPMSM, and determine the MTPA trajectory error based on the direct-axis current, the quadrature-axis current and the equivalent excitation current.

[0100] In some embodiments, the MTPA real-time control parameter includes a flux of the IPMSM, and the calculation unit 802 is further configured to determine a stator resistance based on a stator temperature of the IPMSM, determine a rotor temperature based on a temperature difference between the stator temperature and the rotor temperature and the stator temperature, and determine the flux of the IPMSM based on the rotor temperature.

[0101] In some embodiments, the MTPA real-time control parameter includes a flux of the IPMSM, and the calculation unit 802 is further configured to determine a stator resistance based on a stator temperature of the IPMSM, determine a rotor temperature based on a temperature difference between the stator temperature and the rotor temperature and the stator temperature, and determine the flux of the IPMSM based on the rotor temperature.

[0102] In some embodiments, the calculation unit 802 is further configured to determine a rotor temperature of the IPMSM based on a flux of the IPMSM, determine a stator temperature and a stator resistance based on the rotor temperature and a temperature difference between the rotor temperature and the stator temperature, and determine a direct-axis inductance and a quadrature-axis inductance of the IPMSM by a motor steady-state equation based on the flux and the stator resistance.

[0103] In some embodiments, the closed-loop control unit 806 is further configured to determine, by a proportional-integral controller of the motor, a closed-loop control reference value of the direct-axis current and / or the quadrature-axis current corresponding to the MTPA trajectory error based on the MTPA trajectory error.

[0104] In some embodiments, the closed-loop control unit 806 is further configured to determine, in maximum torque per voltage (MTPV) control, a MTPV trajectory error based on the real-time control parameter, the direct-axis current and the quadrature-axis current; and determine, based on the MTPA trajectory error and / or the MTPV trajectory error, the closed-loop control reference value of the direct-axis current and / or the quadrature-axis current of the IPMSM.

[0105] In some embodiments, the apparatus 800 further comprises an updating unit configured to determine the closed-loop control reference value as a target control current of the IPMSM to implement the driving control of the IPMSM; and update an operating state of the IPMSM based on the closed-loop control reference value.

[0106] Figure 9 A schematic block diagram of an example device 900 that can be used to implement embodiments of the present application is shown. As shown, the device 900 includes a computing unit (CPU) 901 that can perform various suitable actions and processes in accordance with computer program instructions stored in a read-only memory (ROM) 902 or computer program instructions loaded from a storage unit 908 into a random access memory (RAM) 903. Various programs and data used by the device 900, in addition to the computer program instructions, can also be stored in the RAM 903. The CPU 901, the ROM 902, and the RAM 903 are connected to each other by a bus 904. An input / output (I / O) interface 905 is also connected to the bus 904.

[0107] A plurality of components in the device 900 are connected to the I / O interface 905, including: an input unit 906, such as a keyboard, a mouse, etc.; an output unit 907, such as various types of displays, a speaker, etc.; a storage unit 908, such as a magnetic disk, an optical disk, etc.; and a communication unit 909, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 909 allows the device 900 to exchange information / data with other devices through a computer network, such as the Internet, and / or various telecommunication networks.

[0108] The CPU 901 can be various general-purpose and / or special-purpose processing components having processing and computing capabilities. Some examples of the CPU 901 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various specialized artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The CPU 901 executes various methods and processes described above, such as the method 200. For example, in some embodiments, the method 200 can be implemented as a computer software program tangibly embodied in a machine-readable medium, such as the storage unit 908. In some embodiments, part or all of the computer program can be loaded and / or installed onto the device 900 via the ROM 902 and / or the communication unit 909. When the computer program is loaded onto the RAM 903 and executed by the computing unit 901, one or more steps of the method 200 described above can be performed. Alternatively, in other embodiments, the computing unit 901 can be configured to perform the method 200 by other any appropriate means, such as by means of firmware.

[0109] The functions described above in this document can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include field programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), system-on-a-chip systems (SOCs), complex programmable logic devices (CPLDs), etc.

[0110] Program code for carrying out methods of the present application can be written in any combination of one or more programming languages. This program code can be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the program code, when executed by the processor or controller, produces a means for implementing the functions / acts specified in the flowcharts and / or block diagrams. The program code can execute entirely on a machine, partly on a machine, as a stand-alone software package, partly on a machine and partly on a remote machine or entirely on a remote machine or server.

[0111] In the context of the present application, a machine-readable medium can be a tangible medium that contains or stores a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can include but is not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a machine-readable storage medium will include one or more lines of electrical connections, portable computer disks, hard disk drives, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or Flash memory), optical fiber, portable compact disc read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination of the foregoing. Further, while operations are depicted in a particular, chronological sequence, this should not be understood as requiring such order or sequence of operations, or that all illustrated operations be performed to achieve desirable results. In certain circumstances, multitasking and parallel processing can be advantageous. Likewise, while specific implementations are discussed herein, the scope of the present application is not limited to the specific details and representations herein. Some features described in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination.

[0112] Although the subject matter has been described in language specific to structural features and / or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A method for controlling the maximum torque-to-current ratio (MTPA) of an integrated permanent magnet synchronous motor (IPMSM), characterized in that, include: Based on the real-time acquisition parameters of the IPMSM, the real-time control parameters of the MTPA corresponding to the MTPA are calculated through the voltage steady-state equation. Based on the MTPA real-time control parameters, the direct-axis current and quadrature-axis current of the IPMSM, the MTPA trajectory error is determined, and the trajectory error is a function of... , ,in i d , i q and L d , L q These are the direct-axis current, the quadrature-axis current, the direct-axis inductance, and the quadrature-axis inductance, respectively. ψ f For permanent magnet flux linkage; as well as Based on the MTPA trajectory error, the closed-loop control reference value of the direct-axis current corresponding to the MTPA is determined through closed-loop control.

2. The method according to claim 1, characterized in that, The real-time control parameters of the MTPA include the equivalent excitation current of the IPMSM, and based on the real-time control parameters of the MTPA, the direct-axis current and quadrature-axis current of the IPMSM, the MTPA trajectory error is determined to include: Based on the flux linkage, direct-axis inductance, and quadrature-axis inductance of the IPMSM, determine the equivalent excitation current; and The MTPA trajectory error is determined based on the direct-axis current, the quadrature-axis current, and the equivalent excitation current.

3. The method according to claim 1, characterized in that, The real-time control parameters of the MTPA include the flux linkage of the IPMSM, and based on the real-time acquired parameters of the IPMSM, the real-time control parameters of the MTPA corresponding to the MTPA are calculated through the voltage steady-state equation, including: The stator resistance is determined based on the stator temperature of the IPMSM; The rotor temperature is determined based on the temperature difference between the stator temperature and the rotor temperature of the IPMSM, and the stator temperature; and The flux linkage of the IPMSM is determined based on the rotor temperature.

4. The method according to claim 3, characterized in that, The real-time control parameters of MTPA also include the direct-axis inductance and quadrature-axis inductance of the IPMSM, and the real-time control parameters of MTPA corresponding to the MTPA calculated based on the real-time acquired parameters of the IPMSM through the voltage steady-state equation also include: Based on the flux linkage and stator resistance of the IPMSM, the direct-axis inductance and quadrature-axis inductance of the IPMSM are calculated using the motor steady-state voltage equation.

5. The method according to claim 1, characterized in that, Based on the real-time acquired parameters of the IPMSM, the real-time control parameters of the MTPA corresponding to the MTPA are calculated through the voltage steady-state equation, including: The rotor temperature of the IPMSM is determined based on the magnetic flux linkage of the IPMSM. Based on the rotor temperature and the temperature difference between the rotor and stator temperatures, the stator temperature and stator resistance are determined; and Based on the magnetic flux and the stator resistance, the direct-axis inductance and quadrature-axis inductance of the IPMSM are determined by the motor steady-state equation.

6. The method according to claim 1, characterized in that, Based on the MTPA trajectory error, the closed-loop control reference value for the direct-axis current corresponding to the MTPA is determined through closed-loop control, including: The proportional-integral controller of the motor determines the closed-loop control reference value of the direct-axis current corresponding to MTPA based on the MTPA trajectory error.

7. The method according to claim 1, characterized in that, Also includes: Based on the real-time control parameters, direct-axis current, and quadrature-axis current, the MTPV trajectory error is determined in the maximum torque-voltage ratio (MTPV) control. as well as Based on the MTPA trajectory error and / or the MTPV trajectory error, the closed-loop control reference value of the direct-axis current of the IPMSM is determined.

8. The method according to claim 1, characterized in that, Also includes: The closed-loop control reference value is determined as the target control current of the IPMSM to achieve drive control of the IPMSM; as well as The operating status of the IPMSM is updated based on the closed-loop control reference value.

9. A motor controller, comprising: At least one processor; as well as A memory coupled to the at least one processor and having instructions stored thereon, which, when executed by the at least one processor, cause the motor controller to perform the method according to any one of claims 1-8.

10. An electric motor system, comprising: Built-in permanent magnet synchronous motor; as well as The motor controller according to claim 9.

11. A computer program product, characterized in that, Includes machine-executable instructions that, when executed, cause the machine to perform the method according to any one of claims 1-8.

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