Torque control method and device based on permanent magnet synchronous motor and medium

Abstract

The application discloses a torque control method based on a permanent magnet synchronous motor, obtains a current stator temperature of a motor stator at a current moment; estimates a current rotor temperature of a motor rotor at the current moment according to the current stator temperature and a last moment rotor temperature of the motor rotor; obtains a target electromagnetic torque corresponding to a current Q-axis current from a first corresponding relation table of Q-axis currents and electromagnetic torques; obtains a torque compensation value according to the target electromagnetic torque and the current rotor temperature; and estimates an actual motor torque of the permanent magnet synchronous motor by using the torque compensation value. The torque control method based on the permanent magnet synchronous motor, the device and the medium can make the estimated current rotor temperature more accurate, so that the precision of the obtained torque of the permanent magnet synchronous motor is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a torque control method, device and medium based on a permanent magnet synchronous motor. Background Art

[0002] Because permanent magnet synchronous motors have a high proportion of electromagnetic torque, high efficiency and high power density, they are widely used in electric vehicle electric drive systems. Also because permanent magnet synchronous motors have a high proportion of electromagnetic torque, on-board electric drive systems usually use neodymium iron boron with higher magnetic properties to improve the efficiency of on-board electric drive systems.

[0003] However, the existing technologies all control the torque of the permanent magnet synchronous motor through the rotor flux at room temperature. Since the rotor temperature of the permanent magnet synchronous motor affects the rotor flux, thereby affecting the torque accuracy of the motor control, the flux parameters of the permanent magnet synchronous motor are greatly affected by temperature, resulting in low torque control accuracy of the existing technology. Therefore, there is an urgent need for a method that can accurately estimate the torque of the permanent magnet synchronous motor. Summary of the Invention

[0004] The embodiments of the present invention provide a torque control method, device, and medium based on a permanent magnet synchronous motor, which can make the estimated current rotor temperature more accurate, thereby improving the accuracy of the acquired torque of the permanent magnet synchronous motor.

[0005] A first aspect of an embodiment of the present invention provides a torque control method based on a permanent magnet synchronous motor, wherein the permanent magnet synchronous motor includes a motor stator and a motor rotor, and the method includes:

[0006] Obtaining the current stator temperature of the motor stator at the current moment;

[0007] estimating a current rotor temperature of the motor rotor at a current moment according to the current stator temperature and the rotor temperature of the motor rotor at a previous moment;

[0008] Obtaining a target electromagnetic torque corresponding to a current Q-axis current from a preset first correspondence table between Q-axis current and electromagnetic torque, wherein the current Q-axis current is the Q-axis current of the permanent magnet synchronous motor at the current moment;

[0009] Obtaining a torque compensation value according to the target electromagnetic torque and the current rotor temperature;

[0010] The actual motor torque of the permanent magnet synchronous motor is estimated using the torque compensation value.

[0011] Optionally, estimating the current rotor temperature of the motor rotor at the current moment based on the current stator temperature and the rotor temperature of the motor rotor at the previous moment includes:

[0012] Obtaining a stator-rotor heat transfer time constant of the motor stator and the motor rotor;

[0013] The current rotor temperature is obtained according to the stator heat transfer time constant, the current stator temperature and the rotor temperature at the previous moment.

[0014] Optionally, obtaining the current rotor temperature according to the stator heat transfer time constant, the current stator temperature, and the rotor temperature at the previous moment includes:

[0015] Obtaining a first temperature difference between the current stator temperature and the rotor temperature at the previous moment;

[0016] Obtaining a product of the first temperature difference and the inverse of the stator heat transfer time constant;

[0017] The sum of the product and the current stator temperature is taken as the current rotor temperature.

[0018] Optionally, obtaining a stator-rotor heat transfer time constant of the motor stator and the motor rotor includes:

[0019] Obtaining a motor torque stabilization time of the permanent magnet synchronous motor;

[0020] The stator and rotor heat transfer time constant is obtained according to the motor torque stabilization time.

[0021] Optionally, obtaining the target electromagnetic torque corresponding to the current Q-axis current from a preset first correspondence table between the Q-axis current and the electromagnetic torque includes:

[0022] A target Q-axis current matching the current Q-axis current is obtained from the first correspondence, and the electromagnetic torque corresponding to the target Q-axis current is obtained as the target electromagnetic torque, wherein the first correspondence table stores a correspondence between the Q-axis current and the electromagnetic torque when the set temperature and the D-axis current are 0.

[0023] Optionally, obtaining a torque compensation value according to the target electromagnetic torque and the current rotor temperature includes:

[0024] Obtaining a second temperature difference between the current rotor temperature and the set temperature;

[0025] The torque compensation value is obtained according to the second temperature difference, the target electromagnetic torque and the motor rotor flux variation coefficient.

[0026] Optionally, the estimating the actual motor torque of the permanent magnet synchronous motor by using the torque compensation value includes:

[0027] Obtaining a current D-axis current, wherein the current D-axis current is the D-axis current of the permanent magnet synchronous motor at a current moment;

[0028] Obtaining a specific electromagnetic torque corresponding to the current Q-axis current and the current D-axis current from a preset second correspondence table between DQ-axis current and electromagnetic torque;

[0029] The actual motor torque is estimated using the torque compensation value and the specific electromagnetic torque.

[0030] A second aspect of an embodiment of the present invention further provides a torque control device based on a permanent magnet synchronous motor, the device comprising:

[0031] a stator temperature acquisition unit, configured to acquire a current stator temperature of the motor stator of the permanent magnet synchronous motor at a current moment;

[0032] a rotor temperature estimating unit, configured to estimate a current rotor temperature of the motor rotor at a current moment based on the current stator temperature and the rotor temperature of the motor rotor of the permanent magnet synchronous motor at a previous moment;

[0033] an electromagnetic torque acquisition unit, configured to acquire a target electromagnetic torque corresponding to a current Q-axis current from a preset first correspondence table between Q-axis current and electromagnetic torque, wherein the current Q-axis current is the Q-axis current of the permanent magnet synchronous motor at a current moment;

[0034] a torque compensation value acquiring unit, configured to obtain a torque compensation value according to the target electromagnetic torque and the current rotor temperature;

[0035] The motor torque acquisition unit is used to estimate the actual motor torque of the permanent magnet synchronous motor by using the torque compensation value.

[0036] A third aspect of an embodiment of the present invention provides an electronic device comprising a memory and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by one or more processors to execute operating instructions corresponding to the one or more programs for performing the torque control method based on a permanent magnet synchronous motor as provided in the first aspect.

[0037] A fourth aspect of an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the program implements the steps corresponding to the torque control method based on a permanent magnet synchronous motor provided in the first aspect.

[0038] The above one or at least one technical solution in the embodiments of the present application has at least the following technical effects:

[0039] Based on the above technical solution, the current rotor temperature of the motor rotor at the current moment can be estimated based on the current stator temperature and the rotor temperature of the motor rotor at the previous moment, so that the accuracy of the estimated current rotor temperature is higher; and the target electromagnetic torque corresponding to the current Q-axis current is obtained from the first correspondence table, thereby ensuring that the accuracy of the obtained target electromagnetic torque will also be improved; in this way, on the basis of the improvement of the accuracy of the current rotor temperature and the target electromagnetic torque, the accuracy of the torque compensation value obtained based on the current rotor temperature and the target electromagnetic torque will also be improved. When the torque compensation value is used to estimate the actual motor torque of the permanent magnet synchronous motor, due to the high accuracy of the torque compensation value, the accuracy of the estimated actual motor torque of the permanent magnet synchronous motor is also improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A schematic flow chart of a torque control method based on a permanent magnet synchronous motor provided in an embodiment of the present application;

[0041] Figure 2 A schematic diagram of a process for obtaining rotor temperature provided in an embodiment of the present application;

[0042] Figure 3 A block diagram of a torque control device based on a permanent magnet synchronous motor provided in an embodiment of the present application;

[0043] Figure 4 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0044] The main implementation principles, specific implementation methods and corresponding beneficial effects of the technical solutions of the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0045] Example

[0046] Please refer to Figure 1 The embodiment of the present application provides a torque control method based on a permanent magnet synchronous motor, wherein the permanent magnet synchronous motor includes a motor stator and a motor rotor, and the method includes:

[0047] S101, obtaining the current stator temperature of the motor stator at the current moment;

[0048] S102, estimating a current rotor temperature of the motor rotor at a current moment based on the current stator temperature and the rotor temperature of the motor rotor at a previous moment;

[0049] S103, obtaining a target electromagnetic torque corresponding to a current Q-axis current from a preset first correspondence table between Q-axis current and electromagnetic torque, wherein the current Q-axis current is the Q-axis current of the permanent magnet synchronous motor at a current moment;

[0050] S104, obtaining a torque compensation value according to the target electromagnetic torque and the current rotor temperature;

[0051] S105 : Estimate the actual motor torque of the permanent magnet synchronous motor using the torque compensation value.

[0052] The torque control method based on the permanent magnet synchronous motor in the embodiments of this specification is generally used in a vehicle-mounted terminal. The vehicle-mounted terminal can be, for example, a vehicle computer or controller of a target vehicle, and the target vehicle can be a fuel vehicle, an electric vehicle, a hybrid vehicle, etc.

[0053] In the embodiments of this specification, the rotor temperature of the permanent magnet synchronous motor affects the rotor flux, thereby affecting the torque accuracy of the motor control. By accurately estimating the rotor temperature of the motor and, based on the accurate estimation of the rotor temperature, making a relatively accurate estimate of the actual motor torque based on the rotor temperature, the accuracy of the torque control of the permanent magnet synchronous motor is improved. Moreover, based on the accurate estimation of the rotor temperature, the probability of motor damage due to excessive rotor temperature can also be reduced, thereby increasing the service life of the motor. In addition, based on the improvement of the accuracy of the estimated actual motor torque, the probability of vehicle loss of control due to excessive deviation between the actual motor torque and the required torque can also be reduced.

[0054] In step S101, the stator temperature of the motor stator can be obtained in real time through a temperature measuring device, so that the current stator temperature at the current moment can be obtained. The temperature measuring device can be, for example, a temperature measuring instrument and a temperature sensor, etc., and this specification does not impose any specific restrictions.

[0055] After the current stator temperature is acquired, step S102 is executed.

[0056] In step S102, after obtaining the current stator temperature, it is also necessary to obtain the rotor temperature at the previous moment before the current moment, and then input the current stator temperature and the rotor temperature at the previous moment into the motor rotor temperature model to estimate the current rotor temperature of the motor rotor at the current moment, wherein the motor rotor temperature model can be trained based on the historical stator temperature and the historical rotor temperature.

[0057] In one embodiment, when obtaining the current rotor temperature, the stator-rotor heat transfer time constant of the motor stator and the motor rotor can be obtained; then the current rotor temperature is obtained based on the stator heat transfer time constant, the current stator temperature and the rotor temperature at the previous moment.

[0058] Specifically, a first temperature difference between the current stator temperature and the previous rotor temperature can be obtained; the product of the first temperature difference and the inverse of the stator heat transfer time constant can be obtained; and the sum of this product and the current stator temperature can be used as the current rotor temperature. Of course, the sum of the first temperature difference and the current stator temperature, multiplied by a weight, can also be used as the current rotor temperature, and this specification does not impose any specific limitations.

[0059] In one embodiment, when obtaining the motor rotor temperature model, since the motor rotor is heated mainly by the inward diffusion of stator heat during operation, and the motor rotor rotates synchronously with the motor stator, the eddy current effect can be ignored. Compared with the heat dissipation of the motor stator, the frictional heat can also be ignored. That is, the rotor temperature equation is:

[0060]

[0061] In formula 1, T s is the motor stator temperature, T r is the motor rotor temperature, R sr is the thermal resistance coefficient between the stator and rotor of the motor, C is the stator specific heat capacity, m is the stator mass, t is the time, dt is the operation cycle, dT r It is the change of the motor rotor temperature Tr within a single operation cycle.

[0062] Since the calculation of the rotor temperature by formula 1 is relatively large, formula 1 can be simplified to improve the calculation efficiency of obtaining the rotor temperature and improve the real-time performance of obtaining the rotor temperature. For example, Therefore, Formula 1 can be simplified into the following formulas in sequence. The simplification steps are as follows:

[0063] T snew -T rnew =(τ-1)(T rnew -T rold )

[0064] ∴T snew +(τ=1)*T rold =τ*T rnew

[0065] ∴

[0066] ∴

[0067] ∴

[0068] Through the above simplification steps, we can get Formula 2, where T rnew is the estimated value of the rotor temperature at the current moment, T rold is the estimated value of the rotor temperature at the previous moment, Ts The rotor temperature is estimated iteratively using the formula: where is the current stator temperature and τ is the stator-rotor heat transfer time constant. After obtaining the current stator temperature and the rotor temperature at the previous moment, these two values ​​are input into Equation 2 to obtain the current rotor temperature. At this point, Equation 2 represents the motor rotor temperature model.

[0069] In one embodiment, in order to obtain a higher accuracy of the stator and rotor heat transfer time constant, the motor torque stabilization time of the permanent magnet synchronous motor can be first obtained; and then the stator and rotor heat transfer time constant can be obtained based on the motor torque stabilization time.

[0070] Specifically, due to the heating of the motor stator, the temperature of the motor rotor increases, the magnetic flux decreases, and the electromagnetic torque of the motor decreases until the temperature of the motor system stabilizes and the motor torque remains basically unchanged. The motor torque stabilization time can be obtained by measurement as t total , the stator and rotor heat transfer time constant τ can be obtained as:

[0071]

[0072] In another embodiment, after obtaining the motor torque stabilization time t total Then, the stator and rotor heat transfer time constant τ can be It can also be The product of the weight is not specifically limited in this specification.

[0073] In one embodiment, when obtaining the rotor temperature at the previous moment, when the vehicle is just started, the temperature difference between the motor temperature and the controller temperature is less than 5°C. At this time, the motor rotor temperature and the motor stator temperature are equal, and the motor stator initial temperature is equal to the current motor rotor temperature. When the temperature difference between the motor temperature and the controller temperature is greater than 5°C, the vehicle is usually in a short sleep state after the previous driving period, and the motor system has not completely cooled down. At this time, the motor rotor temperature should be consistent with the rotor temperature before the sleep state. The motor rotor temperature is initialized by the above two methods. After the motor rotor temperature is initialized, the rotor temperature is updated using the discretized rotor temperature first-order model (Formula 2 above) to obtain the rotor temperature at the previous moment. As the calculated value of the discretized rotor temperature first-order model is updated, the error effect of the rotor temperature initialization will gradually decrease and will not accumulate, so that the accuracy of the estimated current rotor temperature will also increase over time.

[0074] In actual application, see Figure 2 First, execute step A1, program power-on initialization and hardware initialization, that is, perform hardware initialization after the motor controller is powered on.

[0075] After step A1 is performed, steps A2 and A3 are performed in sequence, wherein step A2 is stator initial temperature reading; step A3 is IGBT initial temperature reading, that is, after hardware initialization is completed, the motor stator temperature and the IGBT temperature (controller temperature) are measured, at this time, the IGBT is not working, and the temperature should be equal to the water temperature.

[0076] Next, step A4 is performed, that is, it is judged whether the temperature difference between the motor temperature and the controller temperature is less than 5℃; if the temperature difference is less than 5℃, step A5 is performed, that is, the current stator temperature is read as the current rotor temperature, at this time, since the temperature difference between the motor temperature and the controller temperature is less than 5℃, it is known that the vehicle is just started, so that the motor rotor temperature is equal to the motor stator temperature. If the temperature difference is greater than 5℃, step A6 is performed, that is, the motor rotor temperature saved in the EEPROM at power-off is read, wherein EEPROM is the abbreviation of Electrically Erasable Programmable Read-Only Memory, when the temperature difference is greater than 5℃, it can be confirmed that the vehicle has only short hibernation after the last driving, and the motor system has not been completely cooled. The motor rotor temperature should be consistent with the rotor temperature before hibernation.

[0077] After steps A5 and A6 are completed, step A7 is performed, that is, the motor rotor temperature first-order model calculation is performed, that is, the current rotor temperature is calculated through formula 2; and step A8 is performed at power-off, that is, the motor rotor temperature at power-off is saved into the EEPROM for standby for the next wake-up state.

[0078] After the current rotor temperature is obtained, step S103 is performed. Step S103 can be performed simultaneously with step S102, or step S103 can be performed first and then step S102 is performed.

[0079] In step S103, the current D-axis current and the current Q-axis current of the permanent magnet synchronous motor at the current time can be acquired by the shaft current monitoring device. After the current Q-axis current is acquired, the target Q-axis current matched with the current Q-axis current can be acquired from the first corresponding relationship, and the electromagnetic torque corresponding to the target Q-axis current is acquired as the target electromagnetic torque, wherein the first corresponding relationship table stores the corresponding relationship between the Q-axis current and the electromagnetic torque when the set temperature and the D-axis current are 0.

[0080] Specifically, after the current Q-axis current is acquired, the current Q-axis current can be taken as a search keyword to search in the first corresponding relationship table, and the target Q-axis current matched with the current Q-axis current is searched, and the electromagnetic torque corresponding to the target Q-axis current is acquired from the first corresponding relationship as the target electromagnetic torque. Wherein, the current Q-axis current and the target Q current are the same.

[0081] In the embodiments of this specification, the set temperature can be any temperature between 20°C and 27°C. Of course, it can also be lower than 20°C or higher than 27°C. The set temperature is usually 25°C as an example, where the set temperature refers to the motor rotor temperature.

[0082] In one embodiment, the historical Q-axis current, historical D-axis current and historical electromagnetic torque of the permanent magnet synchronous motor can be collected at a set temperature to establish a second correspondence table; the historical Q-axis current and historical electromagnetic torque of the permanent magnet synchronous motor can also be collected at a set temperature and when the D-axis current is 0 to establish a first correspondence table.

[0083] In this way, after establishing the first correspondence table and obtaining the current Q-axis current, the current Q-axis current can be directly searched in the first correspondence table to search for the target Q-axis current and the target electromagnetic torque. Since the first correspondence table is established by collecting the historical Q-axis current and the historical electromagnetic torque of the permanent magnet synchronous motor under the conditions of the set temperature and the D-axis current being 0, the accuracy of obtaining the target electromagnetic torque will also be higher. At this time, the target electromagnetic torque is the electromagnetic torque when the rotor temperature is the set temperature, and the motor rotor temperature at this time is the current rotor temperature, and the current rotor temperature is usually different from the set temperature. Therefore, the target electromagnetic torque needs to be adjusted according to the second temperature difference between the current rotor temperature and the set temperature, and then the torque compensation value is obtained, so that the torque compensation value is more accurate.

[0084] After the target electromagnetic torque is acquired, step S104 is executed.

[0085] In step S104, a second temperature difference between the current rotor temperature and the set temperature can be first obtained; then, a torque compensation value can be obtained based on the second temperature difference, the target electromagnetic torque and the motor rotor flux variation coefficient, wherein the motor rotor flux variation coefficient is usually related to the magnetic steel material of the motor rotor.

[0086] Furthermore, when the torque compensation value is obtained according to the second temperature difference, the target electromagnetic torque, and the motor rotor flux variation coefficient, a first product obtained by multiplying the second temperature difference, the target electromagnetic torque, and the motor rotor flux variation coefficient can be used as the torque compensation value. Taking the torque compensation value as ΔT as an example, the specific formula is as follows:

[0087]

[0088] In formula 4, α is the motor rotor flux variation coefficient, is the target electromagnetic torque, t1 is the current rotor temperature, and t0 is the set temperature. Thus, after obtaining the second temperature difference, the target electromagnetic torque, and the motor rotor flux variation coefficient, these values ​​are input into Equation 4 to obtain the torque compensation value ΔT.

[0089] In one embodiment, after obtaining the second temperature difference, the second temperature difference and the second product of the target electromagnetic torque can be directly used as the torque compensation value, or the second product and the third product of the weight can be used as the torque compensation value. This specification does not impose any specific restrictions.

[0090] After the torque compensation value is obtained, step S105 is executed.

[0091] In step S105, since the electromagnetic torque is the torque of electromechanical energy conversion, the torque generated by deducting losses such as friction from the electromagnetic torque is the motor torque of the permanent magnet synchronous motor. In this way, the motor torque of the permanent magnet synchronous motor can be obtained based on the electromagnetic torque. After obtaining the torque compensation value, the torque compensation value can be used to correct the actual electromagnetic torque of the permanent magnet synchronous motor, so that the accuracy of the corrected actual electromagnetic torque is higher, and the accuracy of the actual motor torque obtained based on the corrected actual electromagnetic torque will also be improved accordingly.

[0092] In one embodiment, when using the torque compensation value to estimate the actual motor torque of the permanent magnet synchronous motor, the current D-axis current can be obtained, wherein the current D-axis current is the D-axis current of the permanent magnet synchronous motor at the current moment; then, from a pre-set second correspondence table of DQ-axis current and electromagnetic torque, the specific electromagnetic torque corresponding to the current Q-axis current and the current D-axis current is obtained; and then, the torque compensation value and the specific electromagnetic torque are used to obtain the actual motor torque.

[0093] Specifically, when obtaining the actual motor torque, the torque compensation value can be used to correct the specific electromagnetic torque to obtain the actual electromagnetic torque; and then the actual motor torque can be obtained using the actual electromagnetic torque.

[0094] Specifically, when obtaining the specific electromagnetic torque from the second correspondence table, the specific electromagnetic torque is the electromagnetic torque at the set temperature, the Q-axis current is the current Q-axis current, and the D-axis current is the current D-axis current.

[0095] Specifically, after obtaining the torque compensation value and the specific electromagnetic torque, the actual electromagnetic torque at the current rotor temperature can be accurately obtained based on the torque compensation value and the specific electromagnetic torque, and then the actual motor torque can be estimated by subtracting the torque generated by losses such as friction from the actual electromagnetic torque; since the actual motor torque is estimated based on the actual electromagnetic torque, and the actual electromagnetic torque is obtained based on the torque compensation value and the specific electromagnetic torque, on the basis of the high accuracy of the torque compensation value and the specific electromagnetic torque, the accuracy of the actual electromagnetic torque will also be high, thereby prompting the accuracy of the estimated actual motor torque to be improved accordingly.

[0096] In one embodiment, after obtaining the current D-axis current and the current Q-axis current, Clark transformation and Park transformation can be performed on the current D-axis current and the current Q-axis current. The DQ-axis current obtained by the transformation is used to find the torque at the set temperature in the second correspondence table as the specific electromagnetic torque, and the current Q-axis current (when the current D-axis current is 0) is used to find the torque at the set temperature in the first correspondence table as the target electromagnetic torque. An error analysis is performed on the target electromagnetic torque to obtain the electromagnetic torque error (i.e., the torque compensation value) at the current rotor temperature. The torque compensation value is used to act on the specific electromagnetic torque for torque compensation to obtain the actual electromagnetic torque at the current rotor temperature.

[0097] The above one or at least one technical solution in the embodiments of the present application has at least the following technical effects:

[0098] Based on the above technical solution, the current rotor temperature of the motor rotor at the current moment can be estimated based on the current stator temperature and the rotor temperature of the motor rotor at the previous moment, so that the accuracy of the estimated current rotor temperature is higher; and the target electromagnetic torque corresponding to the current Q-axis current is obtained from the first correspondence table, thereby ensuring that the accuracy of the obtained target electromagnetic torque will also be improved; in this way, on the basis of the improvement of the accuracy of the current rotor temperature and the target electromagnetic torque, the accuracy of the torque compensation value obtained based on the current rotor temperature and the target electromagnetic torque will also be improved. When the torque compensation value is used to estimate the actual motor torque of the permanent magnet synchronous motor, due to the high accuracy of the torque compensation value, the accuracy of the estimated actual motor torque of the permanent magnet synchronous motor is also improved.

[0099] A torque control method based on a permanent magnet synchronous motor is provided in accordance with the above embodiment. The present application also provides a torque control device based on a permanent magnet synchronous motor. Figure 3 , the device comprises:

[0100] The stator temperature acquisition unit 301 is used to acquire the current stator temperature of the motor stator of the permanent magnet synchronous motor at a current moment;

[0101] a rotor temperature estimation unit 302 configured to estimate a current rotor temperature of a motor rotor of the permanent magnet synchronous motor at a current time according to the current stator temperature and a last time rotor temperature of the motor rotor;

[0102] an electromagnetic torque acquisition unit 303 configured to acquire a target electromagnetic torque corresponding to a current Q-axis current of the permanent magnet synchronous motor at the current time from a first correspondence relationship table of Q-axis currents and electromagnetic torques, wherein the current Q-axis current is the Q-axis current of the permanent magnet synchronous motor at the current time;

[0103] a torque compensation value acquisition unit 304 configured to obtain a torque compensation value according to the target electromagnetic torque and the current rotor temperature;

[0104] a motor torque acquisition unit 305 configured to estimate an actual motor torque of the permanent magnet synchronous motor by using the torque compensation value.

[0105] In an optional implementation, the rotor temperature estimation unit 302 is configured to acquire a stator-rotor heat transfer time constant of the motor stator and the motor rotor; and acquire the current rotor temperature according to the stator-rotor heat transfer time constant, the current stator temperature and the last time rotor temperature.

[0106] In an optional implementation, the rotor temperature estimation unit 302 is configured to acquire a first temperature difference value between the current stator temperature and the last time rotor temperature; acquire a product of the first temperature difference value and an inverse of the stator-rotor heat transfer time constant; and take a sum of the product and the current stator temperature as the current rotor temperature.

[0107] In an optional implementation, the rotor temperature estimation unit 302 is configured to acquire a motor torque stabilization time of the permanent magnet synchronous motor; and acquire the stator-rotor heat transfer time constant according to the motor torque stabilization time.

[0108] In an optional implementation, the electromagnetic torque acquisition unit 303 is configured to acquire a target Q-axis current matched with the current Q-axis current from the first correspondence relationship, and acquire an electromagnetic torque corresponding to the target Q-axis current as the target electromagnetic torque, wherein the first correspondence relationship table stores a correspondence relationship between Q-axis currents and electromagnetic torques when a set temperature and a D-axis current are 0.

[0109] In an optional implementation, the torque compensation value acquisition unit 304 is configured to acquire a second temperature difference value between the current rotor temperature and the set temperature; and obtain the torque compensation value according to the second temperature difference value, the target electromagnetic torque and a motor rotor flux linkage variation coefficient.

[0110] In an alternative implementation, the motor torque obtaining unit 305 is configured to obtain a current D-axis current, wherein the current D-axis current is a D-axis current of the permanent magnet synchronous motor at a current time; obtain a specific electromagnetic torque corresponding to the current Q-axis current and the current D-axis current from a pre-set second correspondence table of DQ-axis current and electromagnetic torque; and estimate the actual motor torque by using the torque compensation value and the specific electromagnetic torque.

[0111] With regard to the apparatus in the above embodiments, the specific manners in which the various modules perform operations have been described in detail in the embodiments of the method, and thus will not be described in detail here.

[0112] Figure 4 FIG. 8 is a block diagram of an electronic device 800 for a torque control method based on a permanent magnet synchronous motor according to an example embodiment. The electronic device 800 can be a mobile phone, a computer, a digital broadcast terminal, a messaging device, a game console, a tablet device, a medical device, a fitness device, a personal digital assistant, and the like, for example.

[0113] Referring to Figure 4 The electronic device 800 can include one or more of the following components: a processing component 802, a memory 804, a power supply component 806, a multimedia component 808, an audio component 810, an input / output (I / O) interface 812, a sensor component 814, and a communication component 816.

[0114] The processing component 802 generally controls the overall operation of the electronic device 800 such as operations associated with displaying, making phone calls, data communications, camera operations, and recording operations. The processing component 802 can include one or more processors 820 to execute instructions and manipulate data to complete all or a subset of the steps described in the above methods. Furthermore, the processing component 802 can include one or more modules to facilitate interaction between the processing component 802 and other components. For example, the processing component 802 can include a multimedia module to facilitate the interaction between the multimedia component 808 and the processing component 802.

[0115] The memory 804 is configured to store various types of data to support the operations of the electronic device 800. Examples of these data include instructions for any application or methods operating on the electronic device 800, contact data, phonebook data, messages, pictures, videos, and so on. The memory 804 can be implemented by any type of volatile or non-volatile storage devices or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk, or optical disk.

[0116] The power supply component 806 provides power to the various components of the electronic device 800. The power supply component 806 may include a power management system, one or more power supplies, and other components associated with generating, managing, and distributing power to the electronic device 800.

[0117] The multimedia component 808 includes a screen that provides a presentation interface between the electronic device 800 and the user. In some embodiments, the screen may include a liquid crystal display (LCD) and a touch panel (TP). If the screen includes a touch panel, the screen may be implemented as a touch screen to receive input signals from the user. The touch panel includes one or more touch sensors to sense touches, slides, and gestures on the touch panel. The touch sensor can not only sense the boundaries of the touch or slide action, but also detect the duration and pressure associated with the touch or slide operation. In some embodiments, the multimedia component 808 includes a front camera and / or a rear camera. When the device 800 is in an operating mode, such as a shooting mode or a video mode, the front camera and / or the rear camera can receive external multimedia data. Each front camera and rear camera can be a fixed optical lens system or have focal length and optical zoom capabilities.

[0118] The audio component 810 is configured to present and / or input audio signals. For example, the audio component 810 includes a microphone (MIC), which is configured to receive external audio signals when the electronic device 800 is in an operating mode, such as a call mode, a recording mode, and a voice recognition mode. The received audio signal can be further stored in the memory 804 or transmitted via the communication component 816. In some embodiments, the audio component 810 also includes a speaker for presenting audio signals.

[0119] I / O interface 812 provides an interface between processing component 802 and peripheral interface modules, such as a keyboard, click wheel, buttons, etc. These buttons may include but are not limited to: a home button, volume buttons, a start button, and a lock button.

[0120] The sensor assembly 814 includes one or more sensors for providing various aspects of status assessment for the electronic device 800. For example, the sensor assembly 814 can detect the open / closed state of the device 800, the relative positioning of components, such as the display and keypad of the electronic device 800. The sensor assembly 814 can also detect changes in the position of the electronic device 800 or a component of the electronic device 800, the presence or absence of user contact with the electronic device 800, the orientation or acceleration / deceleration of the electronic device 800, and temperature changes of the electronic device 800. The sensor assembly 814 may include a proximity sensor configured to detect the presence of nearby objects without any physical contact. The sensor assembly 814 may also include a light sensor, such as a CMOS or CCD image sensor, for use in imaging applications. In some embodiments, the sensor assembly 814 may also include an accelerometer, a gyroscope sensor, a magnetic sensor, a pressure sensor, or a temperature sensor.

[0121] The communication component 816 is configured to facilitate wired or wireless communication between the electronic device 800 and other devices. The electronic device 800 can access a wireless network based on a communication standard, such as WiFi, 2G or 3G, or a combination thereof. In an exemplary embodiment, the communication component 816 receives a broadcast signal or broadcast-related information from an external broadcast management system via a broadcast channel. In an exemplary embodiment, the communication component 816 also includes a near field communication (NFC) module to facilitate short-range communication. For example, the NFC module can be implemented based on radio frequency identification (RFID) technology, infrared data association (IrDA) technology, ultra-wideband (UWB) technology, Bluetooth (BT) technology and other technologies.

[0122] In an exemplary embodiment, the electronic device 800 may be implemented by one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components to perform the above methods.

[0123] In an exemplary embodiment, a non-transitory computer-readable storage medium including instructions is also provided, such as a memory 804 including instructions, and the instructions can be executed by the processor 820 of the electronic device 800 to perform the above method. For example, the non-transitory computer-readable storage medium can be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, etc.

[0124] Other embodiments of the present invention will readily occur to those skilled in the art after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

[0125] It should be understood that the present invention is not limited to the exact construction described above and shown in the accompanying drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0126] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A torque control method based on a permanent magnet synchronous motor, wherein the permanent magnet synchronous motor comprises a motor stator and a motor rotor, characterized in that: The method comprises: Obtaining the current stator temperature of the motor stator at the current moment; estimating a current rotor temperature of the motor rotor at a current moment according to the current stator temperature and the rotor temperature of the motor rotor at a previous moment; Obtaining a target electromagnetic torque corresponding to a current Q-axis current from a preset first correspondence table between Q-axis current and electromagnetic torque, wherein the current Q-axis current is the Q-axis current of the permanent magnet synchronous motor at the current moment; Obtaining a torque compensation value according to the target electromagnetic torque and the current rotor temperature; estimating the actual motor torque of the permanent magnet synchronous motor by using the torque compensation value; The estimating the current rotor temperature of the motor rotor at the current moment according to the current stator temperature and the rotor temperature of the motor rotor at the previous moment includes: Obtaining a stator-rotor heat transfer time constant of the motor stator and the motor rotor; Obtaining the current rotor temperature according to the stator-rotor heat transfer time constant, the current stator temperature, and the rotor temperature at the previous moment; The obtaining of the current rotor temperature according to the stator-rotor heat transfer time constant, the current stator temperature, and the rotor temperature at the previous moment includes: Obtaining a first temperature difference between the current stator temperature and the rotor temperature at the previous moment; Obtaining the product of the first temperature difference and the inverse of the stator and rotor heat transfer time constant; The sum of the product and the current stator temperature is taken as the current rotor temperature.

2. The control method according to claim 1, wherein: The obtaining of the stator-rotor heat transfer time constant of the motor stator and the motor rotor includes: Obtaining a motor torque stabilization time of the permanent magnet synchronous motor; The stator and rotor heat transfer time constants are obtained according to the motor torque stabilization time.

3. The control method according to claim 1, wherein: The step of obtaining the target electromagnetic torque corresponding to the current Q-axis current from a preset first correspondence table between the Q-axis current and the electromagnetic torque includes: A target Q-axis current matching the current Q-axis current is obtained from the first correspondence, and the electromagnetic torque corresponding to the target Q-axis current is obtained as the target electromagnetic torque, wherein the first correspondence table stores a correspondence between the Q-axis current and the electromagnetic torque when the set temperature and the D-axis current are 0.

4. The control method according to claim 3, wherein: Obtaining a torque compensation value according to the target electromagnetic torque and the current rotor temperature includes: Obtaining a second temperature difference between the current rotor temperature and the set temperature; The torque compensation value is obtained according to the second temperature difference, the target electromagnetic torque and the motor rotor flux variation coefficient.

5. The control method according to claim 4, wherein: The estimating the actual motor torque of the permanent magnet synchronous motor by using the torque compensation value includes: Obtaining a current D-axis current, wherein the current D-axis current is the D-axis current of the permanent magnet synchronous motor at a current moment; Obtaining the electromagnetic torque corresponding to the current Q-axis current and the current D-axis current from a preset second correspondence relationship table between DQ-axis current and electromagnetic torque; The actual motor torque is estimated using the torque compensation value and the corresponding electromagnetic torque.

6. A torque control device based on a permanent magnet synchronous motor, characterized in that: The device comprises: a stator temperature acquisition unit, configured to acquire a current stator temperature of the motor stator of the permanent magnet synchronous motor at a current moment; a rotor temperature estimating unit, configured to estimate a current rotor temperature of the motor rotor at a current moment based on the current stator temperature and the rotor temperature of the motor rotor of the permanent magnet synchronous motor at a previous moment; The rotor temperature estimation unit is further used to obtain a stator-rotor heat transfer time constant between the motor stator and the motor rotor; Obtaining the current rotor temperature according to the stator-rotor heat transfer time constant, the current stator temperature, and the rotor temperature at the previous moment; Obtaining a first temperature difference between the current stator temperature and the rotor temperature at the previous moment; Obtaining the product of the first temperature difference and the inverse of the stator and rotor heat transfer time constant; taking the sum of the product and the current stator temperature as the current rotor temperature; an electromagnetic torque acquisition unit, configured to acquire a target electromagnetic torque corresponding to a current Q-axis current from a preset first correspondence table between Q-axis current and electromagnetic torque, wherein the current Q-axis current is the Q-axis current of the permanent magnet synchronous motor at a current moment; a torque compensation value acquiring unit, configured to obtain a torque compensation value according to the target electromagnetic torque and the current rotor temperature; The motor torque acquisition unit is used to estimate the actual motor torque of the permanent magnet synchronous motor by using the torque compensation value.

7. An electronic device, characterized in that: The invention comprises a memory and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by one or more processors to execute the operation instructions corresponding to the control method according to any one of claims 1 to 5 contained in the one or more programs.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps corresponding to the control method according to any one of claims 1 to 5 are implemented.

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