Motor torque control method and device, vehicle and storage medium

Abstract

The invention relates to the technical field of motor control, in particular to a motor torque control method and device, a vehicle and a storage medium, and the method comprises the steps that first reactive power and second reactive power of a motor are acquired, and the calculation modes of the first reactive power and the second reactive power are different; calculating a power ratio of the first reactive power to the second reactive power, and determining a first rotor time constant of the motor according to the power ratio and a pre-calibrated reference value; and determining a second rotor time constant as a feed-forward value according to the current temperature of the motor rotor, superposing the first rotor time constant and the second rotor time constant, and controlling the output torque of the motor according to a field orientation angle calculated according to the superposed value. Therefore, the problems that the rotor time constant cannot be accurately estimated and the control precision of the motor torque is reduced due to the influence of voltage harmonic waves and parameter mismatch on the identification precision in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a motor torque control method, device, vehicle and storage medium. Background Art

[0002] With the advancement of power and digital technology, motors have been widely used and developed. They have the advantages of simple structure, high power factor, high efficiency, low noise, and low maintenance cost. Among them, the motor adopts indirect vector control, and the magnetic field orientation angle for completing vector control is obtained based on the rotor time constant. This parameter directly affects the control performance of the asynchronous motor. The motor is affected by many factors, which will cause the rotor time constant to change, so that the rotor time constant used to calculate the magnetic field orientation angle is inconsistent with the actual value, resulting in a deviation between the requested torque issued by the control unit and the actual torque generated by the motor, and the torque accuracy is reduced.

[0003] In the related art, Publication No. (CN107896079A) proposes a rotor time constant identification method based on an extended state observer. The patent uses the output of the state observer as a reference model, the current flux method as an adjustable model, and uses a model reference adaptive method to achieve parameter identification. This method has a certain degree of robustness, but the extended state observer involves multiple adjustment parameters, and the setting is relatively complicated. Publication No. (CN105227022A) proposes an improved rotor time constant identification scheme for reactive power. The scheme uses the reactive power calculated from the d and q axis voltages and currents as a reference model, and the reactive power calculated from the current and synchronous speed as an adjustable model. The rotor time constant is solved by a model reference adaptive method. The scheme is simple and reliable.

[0004] However, the nonlinearity of the inverter in the related technology will cause harmonics in the voltage. These harmonics will cause the calculated reactive power value to deviate from the theoretical value, thus affecting the identification accuracy. The initial rotor time constant value in the model reference adaptation is a fixed value. When the motor rotor time constant changes greatly, the estimated value converges slowly. Summary of the invention

[0005] One of the objects of the present invention is to provide a motor torque control method to solve the problem in the prior art that the rotor time constant cannot be accurately estimated due to the influence of voltage harmonics and parameter mismatch on the identification accuracy, thereby reducing the control accuracy of the motor torque; the second object is to provide a motor torque control device; the third object is to provide a vehicle; the fourth object is to provide a computer-readable storage medium.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A motor torque control method comprises the following steps: obtaining a first reactive power and a second reactive power of a motor, wherein the first reactive power and the second reactive power are calculated in different ways; calculating a power ratio of the first reactive power and the second reactive power, and determining a first rotor time constant of the motor according to the power ratio and a pre-calibrated reference value; determining a second rotor time constant as a feedforward value according to a current temperature of the motor rotor, superimposing the first rotor time constant and the second rotor time constant, and controlling the motor output torque according to a magnetic field orientation angle calculated according to the superimposed value.

[0008] According to the above-mentioned technical means, the embodiment of the present application can calculate the first reactive power and the second reactive power, calculate the reactive power ratio according to the first reactive power and the second reactive power, and determine the rotor time constant with the pre-calibrated reactive power ratio reference value. Since the reactive power ratio is not affected by voltage harmonics and parameter mismatch on the identification accuracy, the rotor time constant can be determined online according to the reactive power ratio and the calibrated value of the power ratio fed back by the system in real time, and then the magnetic field orientation angle of the asynchronous motor can be accurately obtained according to the constant, thereby improving the accuracy of the motor torque control, and the control method is simple and easy to implement digitally. At the same time, the feedforward value of the rotor time constant is determined according to the rotor temperature, thereby accelerating the convergence speed of the online identification process, and can avoid the current loop out of control caused by excessive adjustment of the rotor time constant.

[0009] Further, the method of determining the second rotor time constant as a feedforward value based on the current temperature of the motor rotor also includes: acquiring a corresponding relationship between the rotor temperature and the rotor time constant; and determining the second rotor time constant as a feedforward value based on the current temperature of the motor rotor and the corresponding relationship.

[0010] According to the above-mentioned technical means, the embodiment of the present application can obtain the feedforward value of the rotor time constant through real-time table lookup based on the correspondence between the rotor temperature and the rotor time constant, thereby accelerating the convergence speed of the online identification process, and utilizing the temperature information of the motor during operation to avoid current loop out of control caused by excessive adjustment of the rotor time constant.

[0011] Further, determining the rotor time constant of the motor according to the power ratio and a pre-calibrated reference value includes: calculating a first difference according to the power ratio and the pre-calibrated reference value; and performing proportional-integral adjustment on the first difference to obtain the first rotor time constant.

[0012] According to the above-mentioned technical means, the embodiment of the present application can obtain a first difference value by subtracting the ratio of the first reactive power to the second reactive power from a pre-calibrated reference value, and correct the first rotor time constant online through proportional-integral adjustment. The difference value is used as a judgment condition for the accuracy of the rotor time constant representation, which can effectively overcome the influence of voltage harmonics and parameter mismatch on the identification accuracy.

[0013] Furthermore, before determining the rotor time constant of the motor according to the power ratio and a pre-calibrated reference value, it also includes: obtaining the actual torque and observed torque of the motor during the calibration process; if the second difference between the actual torque and the observed torque is within the allowable error range, the calibration of the reference value is completed, otherwise the reference value of the ratio is recalibrated.

[0014] According to the above-mentioned technical means, the embodiment of the present application can subtract the actual torque obtained by vector control from the observed torque to obtain a second difference. If the second difference is within the error range, the reference value calibration is completed, otherwise it is recalibrated, so that a suitable reference value can be calibrated to avoid affecting the final rotor time constant identification result.

[0015] Further, the calculation formula of the observed torque is:

[0016]

[0017] Among them, P represents the number of pole pairs, L m Represents mutual inductance, L r Represents the rotor inductance, I d represents the d-axis current, I q represents the q-axis current, C s is the rotor time constant, T observed represents the observed value of torque, Ψ d represents the d-axis magnetic flux.

[0018] According to the above technical means, the embodiment of the present application can calculate the magnitude of the observed torque to determine whether the rotor time constant identification is accurate.

[0019] Furthermore, before determining the rotor time constant of the motor according to the power ratio and a pre-calibrated reference value, the method further includes: acquiring a filtering time constant; and filtering the power ratio according to the filtering time constant.

[0020] According to the above technical means, the embodiment of the present application can perform low-pass filtering on the ratio of the first reactive power to the second reactive power according to the filtering time constant, thereby preventing interference from voltage harmonics and noise and effectively improving torque accuracy.

[0021] Further, the obtaining of the first reactive power and the second reactive power of the motor includes: obtaining the current voltage, the current current and the current speed of the motor; calculating the first reactive power of the motor according to the current voltage and the current current, and calculating the second reactive power of the motor according to the current current and the current speed.

[0022] According to the above technical means, the embodiment of the present application can calculate the first reactive power through the current voltage and current current, and calculate the second reactive power through the current current and current speed. It utilizes the characteristic information of the motor itself at the working point and introduces two reactive power calculation models.

[0023] Further, the calculation formula of the first reactive power and the second reactive power is:

[0024]

[0025] Among them, U d represents the d-axis voltage, U q represents the q-axis voltage, I dref Indicates the given current of d axis, I qref Indicates the given current on the q axis, ω e is the synchronous speed, σ is the leakage inductance coefficient, L s represents the stator inductance, ΔQ represents the bias component, Q1 represents the first reactive power, and Q2 represents the second reactive power.

[0026] According to the above technical means, the embodiment of the present application can add a bias component when calculating the first reactive power and the second reactive power, and the bias component is much smaller than the second reactive power. At the same time, the current is replaced by the given current of the d and q axes, thereby expanding the scope of use of reactive power.

[0027] Furthermore, before superimposing the first rotor time constant and the second rotor time constant, the method further includes: performing proportional-integral adjustment on the first rotor time constant.

[0028] According to the above technical means, the embodiment of the present application can perform proportional-integral adjustment on the first rotor time constant, complete the correction of the rotor time constant through control theory, thereby obtaining the correction amount of the rotor time constant and reducing the deviation.

[0029] A motor torque control device comprises: an acquisition module, used to acquire a first reactive power and a second reactive power of a motor, wherein the first reactive power and the second reactive power are calculated in different ways; a calculation module, used to calculate a power ratio of the first reactive power and the second reactive power, and determine a first rotor time constant of the motor according to the power ratio and a pre-calibrated reference value; a control module, used to determine a second rotor time constant as a feedforward value according to a current temperature of the motor rotor, superimpose the first rotor time constant and the second rotor time constant, and control the motor output torque according to a magnetic field orientation angle calculated according to the superimposed value.

[0030] Furthermore, the control module is further used to: obtain the corresponding relationship between the rotor temperature and the rotor time constant; and determine a second rotor time constant as a feedforward value according to the current temperature of the motor rotor and the corresponding relationship.

[0031] A vehicle comprises: a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the motor torque control method as described in the above embodiment.

[0032] A computer-readable storage medium stores a computer program, which is executed by a processor to implement the motor torque control method as described in the above embodiment.

[0033] Beneficial effects of the present invention:

[0034] (1) In the embodiment of the present application, different calculation methods can be used to calculate the first reactive power and the second reactive power, and the reactive power ratio can be calculated according to the first reactive power and the second reactive power, and the rotor time constant can be determined with the pre-calibrated reactive power ratio reference value. Since the reactive power ratio is not affected by the voltage harmonics and the parameter mismatch on the identification accuracy, the rotor time constant can be determined online according to the reactive power ratio and the calibrated value of the power ratio fed back by the system in real time, and then the magnetic field orientation angle of the asynchronous motor can be accurately obtained according to the constant, thereby improving the accuracy of the motor torque control, and the control method is simple and easy to implement digitally;

[0035] (2) The embodiment of the present application can obtain the feedforward value of the rotor time constant by looking up the table in real time based on the corresponding relationship between the rotor temperature and the rotor time constant, thereby accelerating the convergence speed of the online identification process and avoiding the current loop out of control caused by excessive adjustment of the rotor time constant;

[0036] (3) In the embodiment of the present application, the first reactive power and the second reactive power can be obtained by subtracting the obtained value from a pre-calibrated reference value to obtain a first difference value, and the first rotor time constant can be corrected online through proportional-integral regulation;

[0037] (4) In the embodiment of the present application, the actual torque obtained by vector control and the observed torque can be subtracted to obtain a second difference. If the second difference is within the error range, the reference value calibration is completed. Otherwise, the calibration is performed again, so that a suitable reference value can be calibrated. The calibration of the reference value can effectively overcome the influence of voltage harmonics and parameter mismatch on the identification accuracy.

[0038] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A flow chart of a motor torque control method provided by an embodiment of the present invention;

[0040] Figure 2 The parameter K provided by one embodiment of the present invention is set Flow chart of calibration;

[0041] Figure 3 A block diagram of a rotor time constant identification control provided by one embodiment of the present invention;

[0042] Figure 4 A block diagram of a motor torque control device provided by an embodiment of the present invention;

[0043] Figure 5 A schematic structural diagram of a vehicle provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The following will describe the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention, not for limiting the scope of protection of the present invention.

[0045] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0046] Asynchronous motors are widely used in the field of electric vehicles due to their low cost, simple structure and high reliability. Asynchronous motors usually use indirect vector control, and the magnetic field orientation angle for vector control is obtained based on the rotor time constant. This parameter directly affects the control performance of the asynchronous motor. Factors such as temperature rise, skin effect, and electromagnetic saturation of the asynchronous motor will cause the rotor time constant to change, so that the rotor time constant used to calculate the magnetic field orientation angle is inconsistent with the actual value, resulting in a deviation between the requested torque issued by the control unit and the actual torque generated by the motor, and a decrease in torque accuracy. In order to improve the torque accuracy of the asynchronous motor, it is necessary to effectively identify this parameter and act on the motor control loop.

[0047] The related technology does not take into account the following problems: the nonlinearity of the inverter will cause harmonics in the voltage, and these harmonics will cause the calculated reactive power value to deviate from the theoretical value, thus affecting the identification accuracy; the initial rotor time constant value in the model reference adaptation is a fixed value, and when the motor rotor time constant changes greatly, the estimated value converges slowly; in addition, the scheme does not provide an accurate judgment method for the rotor time constant identification.

[0048] To solve the above problems, the embodiment of the present application can use the ratio of the two reactive power calculation models as the feedback quantity, make a difference with the set value, and then obtain the rotor time constant through the proportional integral controller (PI). The set value is based on the principle of minimizing the error between the calculated torque and the measured torque, and is judged to overcome the influence of voltage harmonics and parameter mismatch on the identification accuracy. In addition, the rotor resistance is obtained by temperature estimation as the initial rotor time constant value within a control cycle, which can improve the convergence rate of the estimation result.

[0049] Specifically, Figure 1 A flow chart of a motor torque control method provided in an embodiment of the present application.

[0050] like Figure 1 As shown, the motor torque control method includes the following steps:

[0051] In step S101, a first reactive power and a second reactive power of a motor are acquired, wherein the first reactive power and the second reactive power are calculated in different ways.

[0052] The motor may be an asynchronous motor, etc. The following embodiments take an asynchronous motor as an example.

[0053] It can be understood that the embodiment of the present application can calculate the first reactive power and the second reactive power, which is convenient for the subsequent calculation of the reactive power ratio through the first reactive power and the second reactive power.

[0054] In an embodiment of the present application, obtaining the first reactive power and the second reactive power of the motor includes: obtaining the current voltage, the current current and the current speed of the motor; calculating the first reactive power of the motor according to the current voltage and the current current, and calculating the second reactive power of the motor according to the current current and the current speed.

[0055] The current voltage may be a d-axis voltage and a q-axis voltage, the current current may be a d-axis current and a q-axis current, and the current rotational speed may be a mechanical rotational speed measured by a speed sensor.

[0056] It can be understood that the embodiment of the present application can calculate the first reactive power through the current voltage and current current, and calculate the second reactive power through the current current and current speed, utilizing the characteristic information of the motor itself at the working point and introducing two reactive power calculation models.

[0057] In the embodiment of the present application, the calculation formulas of the first reactive power and the second reactive power are:

[0058]

[0059] Among them, U d represents the d-axis voltage, U q represents the q-axis voltage, I dref Indicates the given current of d axis, I qref Indicates the given current on the q axis, ω e is the synchronous speed, σ is the leakage inductance coefficient, L s represents the stator inductance, ΔQ represents the bias component, Q1 represents the first reactive power, and Q2 represents the second reactive power.

[0060] It can be understood that the embodiment of the present application can add a bias component when calculating the first reactive power and the second reactive power, and the bias component is much smaller than the second reactive power. At the same time, the current is replaced by the given current of the d and q axes, thereby expanding the scope of use of reactive power.

[0061] In step S102, a power ratio of the first reactive power to the second reactive power is calculated, and a first rotor time constant of the motor is determined according to the power ratio and a pre-calibrated reference value.

[0062] The pre-calibrated reference value may be a pre-set value of the ratio of the first reactive power to the second reactive power, and may be specifically calibrated, for example, 1 or 0.8.

[0063] It can be understood that the embodiment of the present application can calculate the reactive power ratio based on the first reactive power and the second reactive power, and determine the rotor time constant with the pre-calibrated reactive power ratio reference value. Since the power ratio is not affected by voltage harmonics and parameter mismatch on the identification accuracy, the rotor time constant can be accurately determined online based on the power ratio subsequently.

[0064] In an embodiment of the present application, the rotor time constant of the motor is determined based on the power ratio and a pre-calibrated reference value, including: calculating a first difference based on the power ratio and the pre-calibrated reference value; and performing proportional-integral adjustment on the first difference to obtain a first rotor time constant.

[0065] It can be understood that the embodiment of the present application can obtain a first difference based on the ratio of the first reactive power to the second reactive power and a pre-calibrated reference value, and the first rotor time constant is corrected online through proportional-integral adjustment. The difference is used as a judgment condition for the accuracy of the rotor time constant representation, which can effectively overcome the influence of voltage harmonics and parameter mismatch on the identification accuracy.

[0066] In an embodiment of the present application, before determining the rotor time constant of the motor based on the power ratio and a pre-calibrated reference value, it also includes: obtaining the actual torque and observed torque of the motor during the calibration process; if the second difference between the actual torque and the observed torque is within the allowable error range, the calibration of the reference value is completed, otherwise the reference value of the ratio is recalibrated.

[0067] Among them, the error range can be specifically calibrated.

[0068] It can be understood that the embodiment of the present application can make a difference between the actual torque obtained by vector control and the observed torque to obtain a second difference. If the second difference is within the error range, the reference value calibration is completed, otherwise it is recalibrated, so that a suitable reference value can be calibrated to avoid affecting the final rotor time constant identification result.

[0069] Specifically, the parameter K in the embodiment of the present application set The calibration process is as follows Figure 2 As shown, including the following:

[0070] Given an initialization K set value, the identification model is based on the set value K set The corresponding rotor time constant is identified. The magnetic field orientation angle is calculated based on the identified rotor time constant. The asynchronous motor performs vector control according to the angle to output torque. The torque sensor collects the K set The torque T corresponding to the value measured At the same time, the observed torque T is calculated based on the current command and the d-axis flux observed , observe whether the difference ΔT between the two is less than [ΔT] designed , if less than [ΔT] designed , which is the parameter K that enables accurate magnetic field orientation set The identified rotor time constant is also accurate. If the condition is not met, update K set Recalibrate the value.

[0071] In the embodiment of the present application, the calculation formula of the observed torque is:

[0072]

[0073] Among them, P represents the number of pole pairs, L m Represents mutual inductance, L r Represents the rotor inductance, I d represents the d-axis current, I q represents the q-axis current, C s is the rotor time constant, T observed represents the observed value of torque, Ψ d represents the d-axis magnetic flux.

[0074] It is understandable that the embodiment of the present application can calculate the magnitude of the observed torque to determine whether the rotor time constant identification is accurate.

[0075] In an embodiment of the present application, before determining the rotor time constant of the motor according to the power ratio and a pre-calibrated reference value, it also includes: obtaining a filtering time constant; and filtering the power ratio according to the filtering time constant.

[0076] Among them, the filtering can be a low-pass filtering, etc., which can be specifically calibrated.

[0077] It can be understood that the embodiment of the present application can perform low-pass filtering on the ratio of the first reactive power to the second reactive power according to the filtering time constant, thereby preventing interference from voltage harmonics and noise and effectively improving torque accuracy.

[0078] In step S103, the second rotor time constant as a feedforward value is determined according to the current temperature of the motor rotor, the first rotor time constant and the second rotor time constant are superimposed, and the magnetic field orientation angle calculated according to the superimposed value controls the motor output torque.

[0079] Here, superposition means adding the first time constant value to the second time constant.

[0080] It can be understood that the embodiment of the present application can determine the rotor time constant online based on the reactive power ratio and the calibrated value of the power ratio fed back by the system in real time, and then accurately obtain the magnetic field orientation angle of the asynchronous motor based on the constant, thereby improving the accuracy of the motor torque control, and the control method is simple and easy to implement digitally.

[0081] In an embodiment of the present application, determining a second rotor time constant as a feedforward value based on the current temperature of the motor rotor also includes: obtaining the correspondence between the rotor temperature and the rotor time constant; and determining the second rotor time constant as a feedforward value based on the current temperature of the motor rotor and the correspondence.

[0082] It can be understood that the embodiment of the present application can obtain the feedforward value of the rotor time constant through real-time table lookup based on the correspondence between the rotor temperature and the rotor time constant, thereby accelerating the convergence speed of the online identification process, and utilizing the temperature information of the motor during operation to avoid current loop out of control caused by excessive adjustment of the rotor time constant.

[0083] In the embodiment of the present application, before superimposing the first rotor time constant and the second rotor time constant, it also includes: performing proportional-integral adjustment on the first rotor time constant.

[0084] It is understandable that the embodiment of the present application can perform proportional-integral adjustment on the first rotor time constant, complete the correction of the rotor time constant through control theory, thereby obtaining a correction amount of the rotor time constant and reducing the deviation.

[0085] According to the motor torque control method proposed in the embodiment of the present application, the power ratio is obtained by calculating the first reactive power and the second reactive power, and the rotor time constant is determined with a pre-calibrated reference value. Since the power ratio is not affected by voltage harmonics and parameter mismatches on the identification accuracy, the rotor time constant can be determined online based on the reactive power ratio and the calibrated value of the power ratio fed back by the system in real time, and then the motor output torque can be accurately determined based on the rotor time constant. This solves the problem in the prior art that the rotor time constant cannot be accurately estimated due to the influence of voltage harmonics and parameter mismatches on the identification accuracy, thereby reducing the control accuracy of the motor torque.

[0086] The motor torque control method of the embodiment of the present application is described below by a specific embodiment, comprising the following steps:

[0087] S101: Get the magnetic field orientation angle of the asynchronous motor for coordinate transformation:

[0088] θ=∫ω e dt=∫ω m +ω s dt (1)

[0089] Among them, ω e is the synchronous speed, ω m =P same T , is the mechanical angular frequency, P is the number of motor pole pairs, ω T , is the mechanical speed of the motor, which can be measured by a speed sensor, ω s =I q / (CI d ) is the slip angular frequency between the stator and rotor, I d ,I q Indicates d and q axis current, C = L r / R r is the rotor time constant, L r, R r are the rotor inductance and rotor resistance respectively.

[0090] S102: It can be seen from formula (1) that the rotor time constant will affect the magnetic field orientation angle, thereby causing the asynchronous motor output torque to be inconsistent with the requested torque. In order to accurately identify the rotor time constant, the reactive power of the asynchronous motor needs to be calculated, as shown below:

[0091]

[0092] Among them, U d , U q To represent the d and q axis voltage, σ=1-L m 2 / L r / L s is the leakage inductance coefficient, L m , L s They represent mutual inductance and stator inductance respectively. Q1 and Q2 represent reactive power models based on voltage and current and reactive power models based on synchronous speed and current respectively.

[0093] S103: The nonlinearity of the inverter and the motor body will cause harmonics in the voltage and current, and the leakage inductance coefficient will also differ from the true value. These factors will cause the reactive power calculation model to deviate from the theoretical value. At the same time, the input of the correction model based on reactive power is power, and the output is the rotor time constant. The dimensions are different, which brings difficulties to the PI controller parameter setting. In order to overcome the above problems, the ratio of the two reactive powers is selected as the feedback of the identification model, as shown below:

[0094]

[0095] S104: To avoid the zero division problem in equation (3), the feedback current in equation (1) is replaced by the current reference, and the bias component is added to the denominator. Equation (2) can be rewritten as:

[0096]

[0097] Among them, I dref ,I qref It represents the given current of d and q axes, which can be obtained by looking up the table according to the requested torque. The given current 2 is the added bias component.

[0098] S105: To further prevent interference from harmonics and noise, low-pass filtering is performed on the feedback:

[0099]

[0100] Where τ represents the filtering time constant.

[0101] S106: The feedback of the identification model is obtained through step S103, and the input of the PI correction model is obtained by subtracting the set value from the feedback. The correction of the rotor time constant is obtained by adjusting the PI controller:

[0102]

[0103] Among them, K set It represents the set value of the ratio of two reactive powers. This value will be calibrated in combination with the experiment. kpower Indicates the error between the set value and the feedback value, K P , K i Respectively represent the proportional and integral terms of the PI controller, C PI Represents the rotor time constant component corrected by the reactive power model.

[0104] S107: The rotor time constant of the asynchronous motor is proportional to the inverse of the rotor resistance, and the resistance has a corresponding relationship with the rotor temperature. Therefore, the rotor time constant can be roughly obtained by obtaining the rotor temperature. The obtained value is used as the feedforward of the PI controller, and then the parameter is corrected in combination with the reactive power model:

[0105]

[0106] Among them, C temp represents the rotor time constant component obtained by looking up the rotor temperature table, f(T) represents the table function relationship between temperature and rotor time constant, and C0 represents the corrected rotor time constant.

[0107] S108: The rotor time constant component after PI correction and the rotor time constant component obtained by temperature table lookup are superimposed to obtain an identified rotor time constant value, which will be used for slip calculation of vector control.

[0108] S109: To determine whether the rotor time constant identification is accurate, it is necessary to observe the torque output. The torque observation value T observed , calculated by the following formula:

[0109]

[0110] Where P represents the pole pair number, Ψ d represents the d-axis magnetic flux.

[0111] S110: Combining formula (6), it can be seen that the identification result of the rotor time constant is consistent with K set The selection of this value will affect the final rotor time constant identification result and the final torque output. If there is no harmonic in the control loop and the parameters are completely accurate, K setThe theoretical value is 1. However, due to voltage harmonics and parameter mismatch, it is difficult to strictly guarantee that this value is 1. Therefore, this value needs to be experimentally calibrated according to the situation, and the calibration result will be stored in the controller for call. set , introduce the following judgment conditions:

[0112] |ΔT|<[ΔT] designed (9)

[0113] Where ΔT = T measured -T observed The output value T representing the actual torque of the asynchronous motor measured and the torque observation value T observed Deviation, [ΔT] designed Indicates the allowable error between the actual torque and the observed torque value.

[0114] S111: If the parameter identification is accurate, the actual d-axis and q-axis coordinate systems of the asynchronous motor completely coincide with the theoretical coordinate system, and the d-axis flux has no component on the q-axis. The torque value calculated by equation (8) should be consistent with the actual torque output value. Therefore, the K can be calculated according to equation (9). set Experimental calibration.

[0115] In specific applications, such as Figure 3 As shown in the figure, the rotor time constant identification process includes: the voltage and current signals are passed through the reactive power calculation module to obtain Q1, and the current and synchronous speed are passed through the reactive power calculation module to obtain Q2. The two are compared to obtain the feedback value K of the identification model. power , the feedback value is filtered and the given value K set The difference is used as the input of the PI controller, and the correction value C of the rotor time constant is obtained through the adjustment of the controller. PI ; At the same time, the controller uses the rotor time constant from the rotor temperature table as the feedforward of the identification model, and superimposes it with the correction value to obtain the final identification result C0; the rotor time constant and the d and q axis currents are used to calculate the slip angular frequency, and the slip angular frequency is superimposed on the mechanical angular frequency to obtain the synchronous speed. The synchronous speed passes through the integration module to obtain the magnetic field orientation angle of the asynchronous motor.

[0116] In summary, the reference value required by the embodiment of the present application can be calibrated according to the accuracy of identification, and the calibration amount is the ratio of two reactive powers, which utilizes the characteristic information of the motor at the working point itself; and combined with the control theory, the calibration amount and the information of real-time feedback from the system are PI-adjusted, and the correction of the rotor time constant is completed through the control scheme; the temperature information of the motor during operation is utilized, and the rotor time constant feedforward is obtained through the rotor temperature, which effectively avoids the current loop out of control caused by excessive adjustment of the rotor time constant; therefore, compared with the scheme of using physical quantities such as voltage, current, and speed in the related technology, the embodiment of the present application proposes a multi-dimensional scheme of control correction + temperature feedforward + motor calibration, which is more comprehensive than the single-dimensional scheme and is of great significance to improving the control performance of the asynchronous motor.

[0117] Next, the motor torque control device proposed according to the embodiment of the present application is described with reference to the accompanying drawings.

[0118] Figure 4 It is a block diagram of a motor torque control method device according to an embodiment of the present application.

[0119] like Figure 4 As shown, the motor torque control method device 10 includes: an acquisition module 100 , a calculation module 200 and a control module 300 .

[0120] Among them, the acquisition module 100 is used to: acquire the first reactive power and the second reactive power of the motor, wherein the calculation methods of the first reactive power and the second reactive power are different; the calculation module 200 is used to: calculate the power ratio of the first reactive power and the second reactive power, and determine the first rotor time constant of the motor according to the power ratio and a pre-calibrated reference value; the control module 300 is used to: determine the second rotor time constant as a feedforward value according to the current temperature of the motor rotor, superimpose the first rotor time constant and the second rotor time constant, and control the output torque of the motor according to the magnetic field orientation angle calculated according to the superimposed value.

[0121] In the embodiment of the present application, the control module 300 is further used to: obtain the corresponding relationship between the rotor temperature and the rotor time constant; and determine the second rotor time constant as a feedforward value according to the current temperature of the motor rotor and the corresponding relationship.

[0122] It should be noted that the above explanation of the motor torque control method embodiment is also applicable to the motor torque control device of this embodiment, and will not be repeated here.

[0123] According to the motor torque control device proposed in the embodiment of the present application, the power ratio is obtained by calculating the first reactive power and the second reactive power, and the rotor time constant is determined with a pre-calibrated reference value. Since the power ratio is not affected by the voltage harmonics and the parameter mismatch on the identification accuracy, the rotor time constant can be determined online according to the reactive power ratio and the calibrated value of the power ratio fed back by the system in real time, and then the motor output torque can be accurately determined according to the rotor time constant, thereby solving the problem in the prior art that the rotor time constant cannot be accurately estimated due to the influence of voltage harmonics and parameter mismatch on the identification accuracy, thereby reducing the control accuracy of the motor torque.

[0124] Figure 5 A schematic diagram of the structure of a vehicle provided in an embodiment of the present application. The vehicle may include:

[0125] A memory 501 , a processor 502 , and a computer program stored in the memory 501 and executable on the processor 502 .

[0126] When the processor 502 executes the program, the motor torque control method provided in the above embodiment is implemented.

[0127] Furthermore, the vehicle also includes:

[0128] The communication interface 503 is used for communication between the memory 501 and the processor 502 .

[0129] The memory 501 is used to store computer programs that can be executed on the processor 502 .

[0130] The memory 501 may include a high-speed RAM (Random Access Memory) memory, and may also include a non-volatile memory, such as at least one disk memory.

[0131] If the memory 501, the processor 502 and the communication interface 503 are implemented independently, the communication interface 503, the memory 501 and the processor 502 can be connected to each other through a bus and communicate with each other. The bus can be an ISA (Industry Standard Architecture) bus, a PCI (Peripheral Component Interconnect) bus or an EISA (Extended Industry Standard Architecture) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 5 Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0132] Optionally, in a specific implementation, if the memory 501, the processor 502 and the communication interface 503 are integrated on a chip, the memory 501, the processor 502 and the communication interface 503 can communicate with each other through an internal interface.

[0133] The processor 502 may be a CPU (Central Processing Unit), or an ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of the present application.

[0134] An embodiment of the present application also provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the motor torque control method as described above is implemented.

[0135] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0136] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0137] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0138] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiment, the N steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array, a field programmable gate array, etc.

[0139] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0140] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A motor torque control method, characterized in that: The following steps are involved: Acquire a first reactive power and a second reactive power of the motor, wherein the first reactive power and the second reactive power are calculated in different ways; Calculating a power ratio of the first reactive power to the second reactive power, and determining a first rotor time constant of the motor according to the power ratio and a pre-calibrated reference value; A second rotor time constant as a feedforward value is determined according to the current temperature of the motor rotor, the first rotor time constant and the second rotor time constant are superimposed, and the motor output torque is controlled according to the magnetic field orientation angle calculated according to the superimposed value.

2. The motor torque control method according to claim 1, characterized in that: The method of determining a second rotor time constant as a feedforward value according to the current temperature of the motor rotor further includes: Obtain the corresponding relationship between rotor temperature and rotor time constant; A second rotor time constant serving as a feedforward value is determined according to the current temperature of the motor rotor and the corresponding relationship.

3. The motor torque control method according to claim 1, characterized in that: Determining the rotor time constant of the motor according to the power ratio and a pre-calibrated reference value includes: Calculating a first difference value according to the power ratio value and the pre-calibrated reference value; The first rotor time constant is obtained by performing proportional-integral adjustment on the first difference.

4. The motor torque control method according to claim 1, characterized in that: Before determining the rotor time constant of the motor according to the power ratio and the pre-calibrated reference value, the method further includes: Obtaining the actual torque and observed torque of the motor during the calibration process; If the second difference between the actual torque and the observed torque is within the allowable error range, the calibration of the reference value is completed; otherwise, the reference value of the ratio is recalibrated.

5. The motor torque control method according to claim 4, characterized in that: The calculation formula of the observed torque is: Among them, P represents the number of pole pairs, L m Represents mutual inductance, L r Represents the rotor inductance, I d represents the d-axis current, I q represents the q-axis current, C s is the rotor time constant, T observed represents the observed value of torque, Ψ d represents the d-axis magnetic flux.

6. The motor torque control method according to claim 1, characterized in that: Before determining the rotor time constant of the motor according to the power ratio and the pre-calibrated reference value, the method further includes: Get the filter time constant; The power ratio is filtered according to the filtering time constant.

7. The motor torque control method according to claim 1, characterized in that: The obtaining of the first reactive power and the second reactive power of the motor comprises: Get the current voltage, current and speed of the motor; The first reactive power of the motor is calculated according to the current voltage and the current current, and the second reactive power of the motor is calculated according to the current current and the current rotation speed.

8. The motor torque control method according to claim 7, characterized in that: The calculation formulas of the first reactive power and the second reactive power are: Among them, U d represents the d-axis voltage, U q represents the q-axis voltage, I dref Indicates the given current of d axis, I qref Indicates the given current on the q axis, ω e is the synchronous speed, σ is the leakage inductance coefficient, L s represents the stator inductance, ΔQ represents the bias component, Q1 represents the first reactive power, and Q2 represents the second reactive power.

9. The motor torque control method according to claim 1, characterized in that: Before superimposing the first rotor time constant and the second rotor time constant, the method further includes: The first rotor time common sense is adjusted proportionally and integrally.

10. A motor torque control device, characterized in that: include: An acquisition module, used for acquiring a first reactive power and a second reactive power of the motor, wherein the first reactive power and the second reactive power are calculated in different ways; a calculation module, configured to calculate a power ratio of the first reactive power to the second reactive power, and determine a first rotor time constant of the motor according to the power ratio and a pre-calibrated reference value; A control module is used to determine a second rotor time constant as a feedforward value according to a current temperature of a motor rotor, superimpose the first rotor time constant and the second rotor time constant, and control the motor output torque according to a magnetic field orientation angle calculated according to the superimposed value.

11. The motor torque control device according to claim 10, characterized in that: The control module is further used to: obtain the corresponding relationship between the rotor temperature and the rotor time constant; and determine a second rotor time constant as a feedforward value according to the current temperature of the motor rotor and the corresponding relationship.

12. A vehicle, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the motor torque control method according to any one of claims 1 to 9.

13. A computer-readable storage medium having a computer program stored thereon, characterized in that: The program is executed by a processor to implement the motor torque control method as described in any one of claims 1 to 9.

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