Motor control method, device, motor, storage medium and processor

Abstract

The present invention discloses a control method, device, motor, storage medium and processor of a motor, the method comprising: obtaining the current speed and given speed of the motor; obtaining the voltage limit value of the inverter in the motor power supply, and obtaining the stator voltage amplitude of the motor; and, according to the current speed, the given speed, the voltage limit value and the stator voltage amplitude, performing weak magnetic compensation and limiting processing, and then predicting the torque and flux of the motor in the future set period to obtain the predicted torque and predicted flux; according to the predicted torque and the predicted flux, constructing an equivalent stator voltage reference vector, and determining the target vector according to the constructed equivalent stator voltage reference vector, so as to control the motor according to the target vector. This scheme can improve the control effect of predicted torque control by simplifying the value function construction method and performing weak magnetic limitation.

Description

Technical Field

[0001] The present invention belongs to the field of motor technology, and specifically relates to a motor control method, device, motor, storage medium and processor, and more particularly to a permanent magnet synchronous motor control method, device, motor, storage medium and processor. Background Art

[0002] Motors (such as permanent magnet synchronous motors) have the advantages of high power density, high output torque, and good dynamic performance, and have been widely used in actual industrial production. Predictive torque control can improve the dynamic performance of motor drive systems (such as permanent magnet synchronous motor drive systems) by predicting the torque and flux at the next moment. Therefore, it has attracted the attention and further research of scholars at home and abroad.

[0003] Considering that the requirements for the speed regulation performance of motors (such as permanent magnet synchronous motors) in industrial applications are gradually increasing, the rapid response capability of motor drive systems (such as permanent magnet synchronous motor drive systems) also needs to be further improved. Predictive torque control can achieve faster response and dynamic effects by predicting the state of the controlled quantity at the next moment. In the model predictive torque control in the relevant scheme, the value function is constructed. The value function is composed of controlled quantities such as torque and magnetic flux. The proportional relationship between the controlled quantities is adjusted by the weight coefficient, so as to achieve the optimization of the comprehensive performance of the motor system (such as the permanent magnet synchronous motor system) by minimizing the value function. However, for the value function, the weight coefficient setting is more complicated, which is not conducive to practical use.

[0004] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0005] The object of the present invention is to provide a motor control method, device, motor, storage medium and processor to solve the problem that in the model predictive torque control of the motor (such as a permanent magnet synchronous motor), a value function is constructed, and the value function is composed of controlled quantities such as torque and magnetic flux, and the value function is complex in structure, which affects the control effect of the predicted torque control. The effect of improving the control effect of the predicted torque control can be achieved by simplifying the value function construction method and performing weak magnetic limitation.

[0006] The present invention provides a method for controlling a motor, comprising: obtaining a current rotational speed and a given rotational speed of the motor; obtaining a voltage limit value of an inverter in a power supply for the motor, and obtaining a stator voltage amplitude of the motor; and, performing magnetic weakening compensation and amplitude limiting processing according to the current rotational speed, the given rotational speed, the voltage limit value, and the stator voltage amplitude, and then predicting the torque and flux of the motor in a future set period to obtain a predicted torque and a predicted flux; constructing an equivalent stator voltage reference vector according to the predicted torque and the predicted flux, and determining a target vector according to the constructed equivalent stator voltage reference vector, so as to control the motor according to the target vector.

[0007] In some embodiments, weak magnetic field compensation and limiting processing are performed according to the current speed, the given speed, the voltage limit value and the stator voltage amplitude, and then the torque and flux of the motor in a future set period are predicted to obtain predicted torque and predicted flux, including: performing PI processing on the difference between the current speed and the given speed to obtain the q-axis reference current of the motor; performing weak magnetic field compensation and out-of-control limiting and compensation processing on the q-axis reference current according to the voltage limit value and the stator voltage amplitude, and calculating the torque reference value and flux reference value of the motor; based on the torque reference value and the flux reference value, using a preset torque-flux prediction model, predicting the torque and flux of the motor in a future set period to obtain predicted torque and predicted flux.

[0008] In some embodiments, the q-axis reference current is subjected to weak magnetic field compensation and out-of-control limiting and compensation processing according to the voltage limit value and the stator voltage amplitude, and the torque reference value and the flux reference value of the motor are calculated, including: the difference between the voltage limit value and the stator voltage amplitude is subjected to PI processing to obtain the weak magnetic field compensation current; wherein the stator voltage amplitude takes the absolute value; the q-axis reference current is subjected to MTPA processing to obtain the d-axis current; the d-axis current is compensated using the weak magnetic field compensation current to obtain the weak magnetic field current; the torque reference value and the flux reference value of the motor are calculated after the weak magnetic field current is subjected to out-of-control limiting and compensation processing.

[0009] In some embodiments, after the weak magnetic current is subjected to out-of-control limiting and compensation processing, the torque reference value and the flux reference value of the motor are calculated, including: after the weak magnetic current is subjected to voltage limit circle limiting processing, the characteristic current clamped at the motor is recorded as the minimum value of the weak magnetic current; the difference between the weak magnetic current and the minimum value of the weak magnetic current is used as the compensation value of the q-axis; after further weakening the weak magnetic current, a further weak magnetic current is obtained; after the minimum value of the weak magnetic current and the further weak magnetic current are subjected to current limit circle limiting, the out-of-control limiting and compensated current values ​​are obtained; and the out-of-control limiting and compensated current values ​​are calculated using a preset torque flux calculation module to obtain the torque reference value and the flux reference value of the motor.

[0010] In some embodiments, an equivalent stator voltage reference vector is constructed according to the predicted torque and the predicted flux, and a target vector is determined according to the constructed equivalent stator voltage reference vector, including: calculating the predicted values ​​of the current d-axis current and q-axis current of the motor at the next sampling moment, i.e., the d-axis current and q-axis current at the next sampling moment, according to the three-phase stator current of the motor; calculating the predicted values ​​of the torque and flux of the motor at the next sampling moment, i.e., the torque and flux at the next sampling moment, according to the d-axis current and q-axis current at the next sampling moment; After the torque and flux at the next sampling moment are beat compensated, the predicted values ​​after the next two sampling moments, i.e., the torque and flux at the next two sampling moments, are obtained; the torque and flux at the next two sampling moments are integrated into an error term between the basic voltage vector and the current stator voltage vector reference value according to the set voltage-current relationship; the error term is used as a value function value for evaluating the torque and flux control performance, and is substituted into the basic voltage vector in the alternative vector set for rolling optimization calculation and evaluation, and the basic voltage vector with the lowest error vector amplitude is selected as the optimal basic voltage vector, i.e., the target vector.

[0011] Matching the above method, the present invention provides a control device for a motor on the other hand, comprising: an acquisition unit, configured to acquire the current speed and given speed of the motor; acquire the voltage limit value of the inverter in the motor power supply, and acquire the stator voltage amplitude of the motor; and a control unit, configured to perform weak magnetic compensation and limiting processing according to the current speed, the given speed, the voltage limit value and the stator voltage amplitude, and then predict the torque and flux of the motor in a future set period to obtain predicted torque and predicted flux; the control unit is also configured to construct an equivalent stator voltage reference vector according to the predicted torque and the predicted flux, and determine a target vector according to the constructed equivalent stator voltage reference vector, so as to control the motor according to the target vector.

[0012] In some embodiments, the control unit performs weak magnetic field compensation and limiting processing according to the current speed, the given speed, the voltage limit value and the stator voltage amplitude, and then predicts the torque and flux of the motor in a future set period to obtain predicted torque and predicted flux, including: performing PI processing on the difference between the current speed and the given speed to obtain the q-axis reference current of the motor; performing weak magnetic field compensation and out-of-control limiting and compensation processing on the q-axis reference current according to the voltage limit value and the stator voltage amplitude, and calculating the torque reference value and flux reference value of the motor; based on the torque reference value and the flux reference value, using a preset torque-flux prediction model to predict the torque and flux of the motor in a future set period to obtain predicted torque and predicted flux.

[0013] In some embodiments, the control unit performs weak magnetic field compensation and out-of-control limiting and compensation processing on the q-axis reference current according to the voltage limit value and the stator voltage amplitude, and calculates the torque reference value and the flux reference value of the motor, including: performing PI processing on the difference between the voltage limit value and the stator voltage amplitude to obtain the weak magnetic field compensation current; wherein the stator voltage amplitude takes the absolute value; performing MTPA processing on the q-axis reference current to obtain the d-axis current; using the weak magnetic field compensation current, compensating the d-axis current to obtain the weak magnetic field current; performing out-of-control limiting and compensation processing on the weak magnetic current, and calculating the torque reference value and the flux reference value of the motor.

[0014] In some embodiments, the control unit calculates the torque reference value and flux reference value of the motor after performing out-of-control limiting and compensation processing on the weak magnetic current, including: after performing voltage limit circle limiting processing on the weak magnetic current, the characteristic current clamped at the motor is recorded as the minimum value of the weak magnetic current; using the difference between the weak magnetic current and the minimum value of the weak magnetic current as the compensation value of the q-axis; after further weakening the weak magnetic current, a further weak magnetic current is obtained; after performing current limit circle limiting on the minimum value of the weak magnetic current and the further weak magnetic current, the out-of-control limiting and compensated current values ​​are obtained; using a preset torque flux calculation module to calculate the out-of-control limiting and compensated current values ​​to obtain the torque reference value and flux reference value of the motor.

[0015] In some embodiments, the control unit constructs an equivalent stator voltage reference vector according to the predicted torque and the predicted flux, and determines a target vector according to the constructed equivalent stator voltage reference vector, including: calculating predicted values ​​of the current d-axis current and q-axis current of the motor at the next sampling moment, i.e., the d-axis current and q-axis current at the next sampling moment, according to the three-phase stator current of the motor; calculating predicted values ​​of the torque and flux of the motor at the next sampling moment, i.e., the torque and flux at the next sampling moment, according to the d-axis current and q-axis current at the next sampling moment; After performing beat compensation on the torque and flux at the next sampling moment, the predicted values ​​after the next two sampling moments, i.e., the torque and flux at the next two sampling moments, are obtained; the torque and flux at the next two sampling moments are integrated into an error term between the basic voltage vector and the current stator voltage vector reference value according to the set voltage-current relationship; the error term is used as a value function value for evaluating the torque and flux control performance, and is substituted into the basic voltage vector in the alternative vector set for rolling optimization calculation and evaluation, and the basic voltage vector with the lowest error vector amplitude is selected as the optimal basic voltage vector, i.e., the target vector.

[0016] Matching the above device, the present invention further provides a motor, including: the control device of the motor described above.

[0017] In accordance with the above method, the present invention provides a storage medium on another aspect, wherein the storage medium includes a stored program, wherein when the program is executed, the device where the storage medium is located is controlled to execute the above-mentioned motor control method.

[0018] In accordance with the above method, the present invention provides a processor on another aspect, wherein the processor is used to run a program, wherein the above motor control method is executed when the program is run.

[0019] Therefore, the scheme of the present invention controls the motor (such as a permanent magnet synchronous motor) by constructing a stator voltage reference vector equivalent to the predicted torque and magnetic flux, judging the optimal vector by comparing the distance between the stator voltage reference vector and the basic voltage vector, and performing weak magnetic limitation; thereby, by simplifying the value function construction method and performing weak magnetic limitation, the control effect of the predicted torque control can be improved.

[0020] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention.

[0021] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1A schematic flow chart of an embodiment of a method for controlling a motor of the present invention;

[0023] Figure 2 A flow chart of an embodiment of the method of the present invention, in which weak magnetic field compensation and amplitude limiting processing are performed according to the current speed, the given speed, the voltage limit value and the stator voltage amplitude, and then the torque and flux of the motor in a future set period are predicted to obtain predicted torque and predicted flux;

[0024] Figure 3 A flow chart of an embodiment of the method of the present invention for calculating the torque reference value and flux linkage reference value of the motor after performing magnetic weakening compensation and out-of-control limiting and compensation processing on the q-axis reference current according to the voltage limit value and the stator voltage amplitude;

[0025] Figure 4 A flow chart of an embodiment of calculating a torque reference value and a flux linkage reference value of the motor after performing out-of-control limiting and compensation processing on the weak magnetic current in the method of the present invention;

[0026] Figure 5 A flow chart of an embodiment of constructing an equivalent stator voltage reference vector according to the predicted torque and the predicted flux linkage, and determining a target vector according to the constructed equivalent stator voltage reference vector in the method of the present invention;

[0027] Figure 6 A schematic structural diagram of an embodiment of a control device for a motor of the present invention;

[0028] Figure 7 It is the coordinate diagram of the current limit circle and the voltage limit ellipse;

[0029] Figure 8 It is a structural schematic diagram of an embodiment of a reference torque and flux generation module;

[0030] Fig. 9 The present invention is a schematic diagram of an overall control flow of an embodiment of a control method for a motor (such as a permanent magnet synchronous motor).

[0031] In conjunction with the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:

[0032] 102 - acquisition unit; 104 - control unit. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] According to an embodiment of the present invention, a method for controlling a motor is provided. Figure 1 The flow chart of an embodiment of the method of the present invention is shown in FIG. The motor control method may include: steps S110 to S130.

[0035] In step S110, the current speed and the given speed of the motor are obtained. The current speed is the motor speed ω fed back by the motor encoder. r , given speed such as given speed ω r * The voltage limit value of the inverter in the motor power supply is obtained, and the stator voltage amplitude of the motor is obtained. The voltage limit value is such as the voltage limit value u of the inverter. max , the stator voltage amplitude is such as the stator voltage amplitude u ref .as well as,

[0036] In step S120, weak magnetic field compensation and amplitude limiting processing are performed according to the current speed, the given speed, the voltage limit value and the stator voltage amplitude, and then the torque and flux of the motor in a future set period are predicted to obtain the predicted torque and predicted flux.

[0037] In some embodiments, in combination Figure 2 The method of the present invention shown in the figure performs weak magnetic compensation and limiting processing according to the current speed, the given speed, the voltage limit value and the stator voltage amplitude, and then predicts the torque and flux of the motor in a future set period to obtain the predicted torque and predicted flux, which further illustrates the specific process of performing weak magnetic compensation and limiting processing according to the current speed, the given speed, the voltage limit value and the stator voltage amplitude, and then predicting the torque and flux of the motor in a future set period to obtain the predicted torque and predicted flux in step S120, including: steps S210 to S230.

[0038] Step S210, after PI processing, the difference between the current speed and the given speed is processed to obtain the q-axis reference current of the motor, such as the q-axis reference current i q * .

[0039] Step S220, according to the voltage limit value and the stator voltage amplitude, the q-axis reference current is subjected to weak magnetic compensation, loss of control limiting and compensation processing, and the torque reference value and flux linkage reference value of the motor are calculated. e * , the flux reference value is as follows s * .

[0040] In some embodiments, in combination Figure 3 The method of the present invention is shown as a flow chart of an embodiment of calculating the torque reference value and flux reference value of the motor after performing weak magnetic compensation and out-of-control limiting and compensation processing on the q-axis reference current according to the voltage limit value and the stator voltage amplitude. It further illustrates the specific process of calculating the torque reference value and flux reference value of the motor after performing weak magnetic compensation and out-of-control limiting and compensation processing on the q-axis reference current according to the voltage limit value and the stator voltage amplitude in step S220, including: steps S310 to S340.

[0041] Step S310, after performing PI processing on the difference between the voltage limit value and the stator voltage amplitude, a weak magnetic compensation current is obtained, such as a weak magnetic compensation current Wherein, the stator voltage amplitude is an absolute value.

[0042] Step S320, after performing MTPA processing on the q-axis reference current, a d-axis current is obtained, such as the d-axis current

[0043] Step S330, using the weak magnetic field compensation current to compensate the d-axis current to obtain a weak magnetic field current, such as a weak magnetic field current

[0044] Step S340 , after performing out-of-control limiting and compensation processing on the weak magnetic current, a torque reference value and a flux linkage reference value of the motor are calculated.

[0045] Figure 7 The coordinate diagram of the current limit circle and the voltage limit ellipse. For a specific motor (such as a permanent magnet synchronous motor) control system, its parameters are fixed, so it has its corresponding voltage limit ellipse and current limit circle model. For the convenience of analysis, Figure 7 The figure shows that the two are placed in the same coordinate system. Figure 7 As shown in the figure, the current limit circle amplitude is a constant value, that is, I max , and the radius of the voltage limit ellipse decreases as the motor speed increases. Point C is the center of the voltage limit ellipse. The current value here is the characteristic current value I of the motor (such as permanent magnet synchronous motor) c. As the motor speed increases, the motor (such as a permanent magnet synchronous motor) control system enters a state of deep magnetic weakening area. When the motor (such as a permanent magnet synchronous motor) speed rises to the point where the voltage limit ellipse and the current limit circle are only tangent at point A, the motor (such as a permanent magnet synchronous motor) speed is ω1, and the motor (such as a permanent magnet synchronous motor) control system is in a critical state. When the motor (such as a permanent magnet synchronous motor) speed is further increased to ω2, the voltage limit ellipse is further reduced. At this time, there is no intersection between the current limit circle and the voltage limit ellipse. At this time, point A is always on the left side of the voltage limit ellipse. In this way, there will be a large error between the actual current of the motor (such as a permanent magnet synchronous motor) and the reference current of the given torque and flux generation module of the motor (such as a permanent magnet synchronous motor) control system. The calculated torque and flux reference values ​​are inaccurate. When the given torque and flux reference values ​​are inaccurate, the control of the motor (such as a permanent magnet synchronous motor) control system will be inaccurate or even out of control. Therefore, the above situation should be avoided in the actual control system.

[0046] In the scheme of the present invention, the problem of current runaway caused by excessive weak magnetic current in the weak magnetic speed-up method is taken into consideration, so it is necessary to limit it. Different from the weak magnetic control in the related scheme, in order to avoid the current runaway caused by the current not following in the deep weak magnetic area, the scheme of the present invention adopts a weak magnetic limiting method to prevent the d-axis current from appearing on the left side of the characteristic current, and at the same time adopts a segmented weak magnetic method, and the difference before and after the d-axis current is limited is used as the weak magnetic compensation value of the q-axis current, so as to realize the second step of weak magnetic and achieve the purpose of speed increase.

[0047] Figure 8 It is a structural schematic diagram of an embodiment of a reference torque and flux generation module. Figure 8 The reference torque and flux generation module is shown in FIG. 1 , which is mainly composed of three parts: the weak magnetic compensation module, the loss of control limit and compensation module and the final torque flux calculation module. In the weak magnetic compensation module, the voltage limit value u max and the stator voltage amplitude u ref The absolute value of the comparison is passed through the PI controller to generate a weak magnetic compensation current q-axis reference current i q * After MTPA (maximum torque current ratio control) calculation, the d-axis current is obtained Through the weak magnetic compensation current After compensation, the weak magnetic current can be obtained At this time, the out-of-control limiting and compensation module is entered.

[0048] In some embodiments, in combination Figure 4The method of the present invention is shown as a flowchart of an embodiment of calculating the torque reference value and the flux reference value of the motor after the weak magnetic current is subjected to out-of-control limiting and compensation processing, further illustrating the specific process of calculating the torque reference value and the flux reference value of the motor after the weak magnetic current is subjected to out-of-control limiting and compensation processing in step S340, including: steps S410 to S450.

[0049] Step S410, after the weak magnetic current is subjected to voltage limit circle limiting processing, it is clamped to the characteristic current of the motor, such as the characteristic current I c , recorded as the minimum value of the weak magnetic current, such as

[0050] Step S420, using the difference between the weak magnetic current and the minimum value of the weak magnetic current as the compensation value of the q axis, such as Δi q .

[0051] Step S430, further weakening the magnetic field current to obtain a further magnetic field weakening current, that is, a second magnetic field weakening current.

[0052] Step S440, after the minimum value of the weakening magnetic current and the further weakening magnetic current are limited by the current limit circle, the out-of-control limiting and compensation current values ​​are obtained.

[0053] Step S450, using a preset torque flux calculation module to calculate the current value of the out-of-control limiting and compensation, to obtain a torque reference value and a flux reference value of the motor.

[0054] See also Figure 8 In the example shown, in the out-of-control limiting and compensation module, the field weakening current After being limited, it is clamped at the characteristic current I c , which is recorded as As the speed increases, the weak magnetic current decreases to its minimum value. At this time, the d-axis current cannot change any more, and the q-axis current can be reversely compensated to continue with magnetic weakening. Figure 8 As shown in With the weak magnetic current after limiting Make a difference and get the compensation value Δi of the q axis q Since the d-axis current in weak magnetic control is always negative, Δi q is also a negative value, that is, further weak magnetic control is achieved by reducing the q-axis current value. cThe method of limiting the d-axis current makes the current command of the motor (such as a permanent magnet synchronous motor) control system to the right of the characteristic current point throughout the whole process, that is, to ensure that the motor (such as a permanent magnet synchronous motor) control system will not be unstable. The characteristic current is an inherent parameter of the motor (such as a permanent magnet synchronous motor) system, which can be obtained by a variety of methods, which will not be repeated here.

[0055] There is a calculation and a limiting process in this branch, where the calculation process is: according to the d-axis weak magnetic current The current iq of the q axis at the same moment is obtained, and its calculation formula is:

[0056]

[0057] Where, T e_fw is the maximum torque that the system can output under weak magnetic conditions, p is the number of pole pairs, ψ f is the rotor permanent magnet flux, L d , L q is the d and q axis inductance, and according to this formula, i q After that, after the first level of limiting, that is, the current limit circle limiting, according to the previous discussion, it can be known that no matter how the current changes, its d and q axis currents must meet the current limit circle limit. The current limit circle formula here is: In the formula, I max is the maximum current value allowed by the motor, that is Figure 7 Medium current limit circle radius value.

[0058] Depend on Figure 8 As shown in the example, the voltage and current in the control system of the motor (such as a permanent magnet synchronous motor) need to meet the corresponding voltage limit ellipse and current limit circle limits. The current value generated in the out-of-control limit and compensation module is input into the torque and flux calculation module to calculate the reference value T of the torque and flux. e * and ψ s * .

[0059] Step S230, predicting the torque and flux of the motor in a future set period according to the torque reference value and the flux reference value using a preset torque-flux prediction model to obtain a predicted torque and a predicted flux.

[0060] Considering the actual use characteristics of motors (such as permanent magnet synchronous motors), they are often required to operate in a wider range of speed regulation. As the speed of the motor (such as permanent magnet synchronous motor) increases, the back electromotive force of the motor (such as permanent magnet synchronous motor) will be limited by the DC side voltage of the inverter, so the predictive torque control method in the relevant scheme cannot achieve the purpose of speed expansion. In order to enable the motor (such as permanent magnet synchronous motor) to operate stably in a wider speed range, the motor system (such as permanent magnet synchronous motor system) needs to adopt a weak magnetic control method to achieve weak magnetic speed increase and widen its speed regulation range.

[0061] That is to say, as the motor speed increases, the predicted torque control method in the relevant scheme cannot meet its speed regulation requirements, so it is necessary to adopt weak magnetic field control to increase its operating speed through the method of weak magnetic field speed increase. In the weak magnetic field control in the relevant scheme, if the given current is large and the motor system (such as a permanent magnet synchronous motor system) is in a deep weak magnetic field area, if the current trajectory planning is unreasonable, it is easy to cause the actual current to fail to follow the given current, that is, the current is out of control, which will also cause the motor system (permanent magnet synchronous motor system) to be unstable.

[0062] Considering that in the predictive torque control method, as the speed increases, the control system needs to enter the deep magnetic weakening area, and as the current vector moves on the current limit circle, the current is prone to not follow, resulting in system out of control or even a runaway situation. The solution of the present invention adopts a magnetic weakening control method in the model predictive torque control method, compares the equivalent synthesized stator voltage reference value with the inverter withstand voltage threshold, generates a magnetic weakening compensation current after passing through the PI regulator, compensates the d-axis current, and realizes magnetic weakening control.

[0063] In this way, compared with the model prediction torque control method in the related schemes, the scheme of the present invention adopts a weak magnetic speed increase method, in which the stator voltage reference value synthesized by the torque and magnetic flux equivalent is compared with the inverter withstand voltage threshold, and a weak magnetic compensation current is generated after passing through the PI regulator (i.e., proportional-integral regulator) to compensate the d-axis current and realize weak magnetic control.

[0064] In step S130, an equivalent stator voltage reference vector is constructed according to the predicted torque and the predicted flux, and a target vector is determined according to the constructed equivalent stator voltage reference vector to control the motor according to the target vector.

[0065] The solution of the present invention proposes a model predictive torque control method, that is, a method for suppressing weak magnetic field out of control based on model predictive torque control. A weak magnetic field control method is adopted in the model predictive torque control method, and the control method can realize weak magnetic field compensation by means of voltage signal feedback, and adopt a limiting method and a segmented weak magnetic field method to achieve the purpose of weak magnetic field speed increase, which can improve the control effect of predictive torque control of motors (such as permanent magnet synchronous motors).

[0066] In some embodiments, in combination Figure 5 The method of the present invention shown is a flow chart of an embodiment of constructing an equivalent stator voltage reference vector according to the predicted torque and the predicted magnetic flux, and determining the target vector according to the constructed equivalent stator voltage reference vector, further illustrating the specific process of constructing an equivalent stator voltage reference vector according to the predicted torque and the predicted magnetic flux, and determining the target vector according to the constructed equivalent stator voltage reference vector in step S130, including: steps S510 to S540.

[0067] Step S510, based on the three-phase stator current of the motor, calculate the predicted values ​​of the current d-axis current and q-axis current of the motor at the next sampling time, that is, the d-axis current and q-axis current at the next sampling time, such as i dq (k+1).

[0068] Step S520, based on the d-axis current and the q-axis current at the next sampling moment, calculate the predicted values ​​of the torque and flux of the motor at the next sampling moment, that is, the torque and flux at the next sampling moment, such as T e (k+1) and ψ s (k+1); After performing beat compensation on the torque and flux at the next sampling moment, the predicted values ​​after the next two sampling moments are obtained, that is, the torque and flux at the next two sampling moments, such as T e (k+2) and ψ s (k+2).

[0069] The predicted current value at time k+1 can be obtained from the mathematical equation of the motor and Euler's formula. Based on the predicted current value at time k+1, the predicted torque and flux at time k+1 can be calculated. At this point, based on the deadbeat principle (the deadbeat principle is to make the current reference value equal to the predicted value at the next moment), the predicted torque and flux at time k+2 after two sampling moments are obtained.

[0070] Step S530, integrating the torque and flux at the next two sampling moments into an error term between the basic voltage vector and the current stator voltage vector reference value according to the set voltage-current relationship, so as to construct an equivalent stator voltage reference vector.

[0071] Step S540, taking the error term as the value function value for evaluating the torque and flux control performance, substituting it into the basic voltage vector in the candidate vector set for rolling optimization calculation and evaluation, and selecting the basic voltage vector with the lowest error vector amplitude as the optimal basic voltage vector, i.e., the target vector.

[0072] Considering that in the prediction torque control of permanent magnet synchronous motor in the related scheme, the value function is complex to construct, involves many controlled quantities, and the weight coefficient setting is complex. The scheme of the present invention adopts a new value function construction method to construct an equivalent stator voltage reference vector with predicted torque and flux, and judges the optimal vector by comparing the distance between the stator voltage reference vector and the basic voltage vector to control the motor (such as permanent magnet synchronous motor).

[0073] Thus, compared with the model prediction torque control method in the related schemes, the scheme of the present invention adopts a new value function construction method, which synthesizes the stator voltage reference vector by torque and magnetic flux equivalent, and judges the optimal vector by comparing the distance between the voltage reference vector and the basic voltage vector to control the motor (such as a permanent magnet synchronous motor).

[0074] Fig. 9 FIG. 1 is a schematic diagram of an overall control flow of an embodiment of a control method for a motor (such as a permanent magnet synchronous motor). Fig. 9 As shown, the motor encoder feeds back the motor speed ω r , with the given speed ω r * Comparison, after passing through the PI regulator, generates the q-axis reference current i q * , and then by Figure 8 The reference torque and flux generation module shown generates reference values ​​T of torque and flux. e * and ψ s * . Sample the three-phase current i from the motor system A,B,C , combined with the position signal θ output by the encoder r , after coordinate transformation, the current signal i in the rotating coordinate system is obtained d,q Considering the signal delay in the digital system, deadbeat compensation is introduced here to compensate the signal of one sampling cycle and obtain the current signal i after one cycle. d,q (k+1). According to the prediction model of torque and flux, the predicted value T of torque and flux after two cycles is obtained. e (k+2) and ψ d,q (k+2), these two predicted values ​​can be equivalently synthesized into the stator voltage vector u ref , analyze and compare the stator voltage vector u refThe error relationship between the stator voltage vector and the basic voltage vector can be used to obtain the optimal vector to act on the inverter and control the motor system. ref The absolute value is fed back to the weak magnetic field compensation module to generate weak magnetic field compensation current.

[0075] See also Fig. 9 In the example shown, a control method of a permanent magnet synchronous motor proposed by the solution of the present invention, more specifically a method for suppressing magnetic field loss based on model predictive torque control, comprises:

[0076] Step 1: First sample the three-phase stator current, and transform the current from the three-phase ABC stationary axis system to the dq rotating axis system through coordinate transformation to obtain i d and i q Through the Euler forward formula, the predicted values ​​i of the current d-axis current and q-axis current at the next sampling time are obtained. dq (k+1), expressed as:

[0077]

[0078] This formula is calculated from the motor system voltage equation and the forward Euler formula, where i d( k+1) and i q (k+1) are the dq axis current values ​​at time k+1, i d( k) and i q (k) are the dq axis current values ​​at time k, T s is the sampling period, R s is the stator resistance, L d , L q are the d-axis and q-axis inductance values, respectively, v d (k) and v q (k) are the dq axis voltage values ​​at time k, ψ f is the rotor permanent magnet flux, ω r is the motor electrical angular velocity.

[0079] Step 2: According to the current i dq (k+1) and the torque and flux equations, the predicted values ​​of torque and flux at the next sampling time T can be obtained. e (k+1) and ψ s (k+1), in order to compensate for the delay of the digital system, according to the deadbeat principle, the current reference value is equal to the predicted value at the next sampling moment. Combined with the aforementioned one-beat prediction control, the motor (such as a permanent magnet synchronous motor) can control the current value T of the control system. e * and ψ s * Equal to the predicted value T after two sampling moments e (k+2) and ψs (k+2).

[0080] The one-shot predictive control mentioned above refers to the calculation process of obtaining the torque and flux prediction values ​​at time k+1 from the current at time k+1 shown in formula (1) and the torque and flux calculation formula. The final result is the torque and flux prediction value T at time k+1. e (k+1) and ψ s (k+1).

[0081] Step 3: The predicted values ​​of torque and flux T e (k+2) and ψ s (k+2), according to the voltage-current relationship, is integrated into the error term between the basic voltage vector and the current stator voltage vector reference value, which is represented by V err Indicates that V err =|u ref -V i |.

[0082] Among them, u ref is the predicted value of torque and flux T e (k+2) and ψ s (k+2) equivalent synthesized stator reference voltage vector, V i is the basic voltage vector, then V err That is, as the value function value for evaluating the torque and flux control performance, when selecting the basic voltage vector, it can be substituted into the basic voltage vector in the candidate vector set for rolling optimization calculation and evaluation to select the error vector V err The basic voltage vector with the lowest amplitude is the optimal basic voltage vector.

[0083] Step 4: When the speed is further increased, the motor (such as a permanent magnet synchronous motor) control system enters the weak magnetic field region, and the equivalent reference vector u ref The amplitude is taken and fed back to the weak magnetic module. After being compared with the maximum voltage threshold of the inverter, the weak magnetic compensation current is obtained through the PI regulator. The speed information fed back by the encoder is compared with the given speed, and then the q-axis current reference value is obtained through the PI regulator. Then, the MTPA calculation is combined with the weak magnetic compensation current to obtain the weak magnetic d-axis current. The limiting module limits the d-axis current according to the parameters of the motor (such as permanent magnet synchronous motor) control system, that is, the characteristic current I c It is limited, and the weak magnetic current is obtained after limiting The difference before and after the limit is used as the weak magnetic compensation value of the q-axis current, that is, the compensation value Δi q Since the d-axis current in weak magnetic control is always negative, Δi qIt is also a negative value, that is, further weak magnetic control is achieved by reducing the q-axis current value, and the weak magnetic q-axis current is obtained.

[0084] Step 5. After obtaining the d-axis current and q-axis current after weak magnetic field, the d-axis current and q-axis current must meet the restrictions of the current limit circle. Then the reference values ​​of the torque and flux linkage can be calculated. The calculation formula for the electromagnetic torque of the permanent magnet synchronous motor is:

[0085]

[0086] This formula is the torque calculation formula of permanent magnet synchronous motor, where T e * represents electromagnetic torque, p represents the number of motor pole pairs, ψ d and ψ q They represent the stator flux components of the dq axis respectively, i d and i q Represent the dq axis current components respectively.

[0087] Among them, according to the reference values ​​of torque and flux obtained in step 5, combined with the prediction and zero-beat calculation in step 2, a new round of torque and flux prediction values ​​can be obtained, and then the motor (such as permanent magnet synchronous motor) control system can be controlled.

[0088] Step 6. According to the calculation relationship between the motor stator current, torque and flux mentioned above, the flux expression is:

[0089]

[0090] in:

[0091]

[0092] This formula is based on the calculation formula of magnetic flux, and is used to calculate the dq-axis magnetic flux for the variables in the model. It represents the d-axis weak magnetic current after being limited by the limit value. According to the torque calculation formula, Calculated q-axis current.

[0093] In formula (4), when calculating the d-axis and q-axis flux linkages, the d-axis and q-axis current values ​​after magnetic weakening are used, and the d-axis current uses the magnetic weakening current after amplitude limiting. Figure 8 It is intuitively reflected in the structure.

[0094] The scheme of the present invention adopts a method of limiting and compensating for loss of control in the weak magnetic speed-up link of the model predictive torque control, wherein the stator voltage feedback value of the weak magnetic compensation module is the stator voltage amplitude equivalent to the predicted torque and the predicted magnetic flux in the model predictive torque control. On the one hand, the equivalent stator voltage vector is used as a value function to screen the basic voltage vector for driving the motor system. On the other hand, its amplitude is taken as the voltage feedback value and fed back to the weak magnetic compensation module to perform weak magnetic compensation on the d-axis current. After the weak magnetic compensation of the d-axis current, in order to limit it from being too large, a method of limiting the d-axis current value by characteristic current is adopted to strictly limit the d-axis current value to the right side of the characteristic current value, so as to ensure the stability of the system. The difference before and after the limiting is used as the weak magnetic compensation value of the q-axis current to achieve the second step of weak magnetic field and weak magnetic speed-up.

[0095] After a large number of experimental verifications, the technical solution of this embodiment is adopted, by constructing an equivalent stator voltage reference vector with predicted torque and flux linkage, judging the optimal vector by comparing the distance between the stator voltage reference vector and the basic voltage vector, and performing weak magnetic restriction to control the motor (such as a permanent magnet synchronous motor). Therefore, by simplifying the value function construction method and performing weak magnetic restriction, the control effect of predicted torque control can be improved.

[0096] According to an embodiment of the present invention, a motor control device corresponding to the motor control method is also provided. Figure 6 The schematic diagram of the structure of an embodiment of the device of the present invention is shown. The control device of the motor may include: an acquisition unit 102 and a control unit 104.

[0097] The acquisition unit 102 is configured to acquire the current speed and the given speed of the motor, the current speed being the motor speed ω fed back by the motor encoder. r , given speed such as given speed ω r * The voltage limit value of the inverter in the motor power supply is obtained, and the stator voltage amplitude of the motor is obtained. The voltage limit value is such as the voltage limit value u of the inverter. max , the stator voltage amplitude is such as the stator voltage amplitude u ref The specific functions and processing of the acquisition unit 102 refer to step S110. And,

[0098] The control unit 104 is configured to perform weak magnetic field compensation and limit processing according to the current speed, the given speed, the voltage limit value and the stator voltage amplitude, and then predict the torque and flux of the motor in a future set period to obtain the predicted torque and predicted flux. The specific functions and processing of the control unit 104 refer to step S120.

[0099] In some implementations, the control unit 104 performs magnetic field weakening compensation and amplitude limiting processing according to the current speed, the given speed, the voltage limit value, and the stator voltage amplitude, and then predicts the torque and flux of the motor in a future set period to obtain the predicted torque and predicted flux, including:

[0100] The control unit 104 is further configured to perform PI processing on the difference between the current speed and the given speed to obtain a q-axis reference current of the motor, such as the q-axis reference current i q * The specific functions and processing of the control unit 104 can also be found in step S210.

[0101] The control unit 104 is further configured to calculate the torque reference value and flux linkage reference value of the motor after performing magnetic field weakening compensation, loss of control limiting and compensation processing on the q-axis reference current according to the voltage limit value and the stator voltage amplitude. e * , the flux reference value is as follows s * The specific functions and processing of the control unit 104 can also be found in step S220.

[0102] In some implementations, the control unit 104 performs magnetic weakening compensation and out-of-control limiting and compensation processing on the q-axis reference current according to the voltage limit value and the stator voltage amplitude, and calculates the torque reference value and the flux linkage reference value of the motor, including:

[0103] The control unit 104 is further configured to perform PI processing on the difference between the voltage limit value and the stator voltage amplitude to obtain a weak magnetic compensation current, such as a weak magnetic compensation current The stator voltage amplitude is an absolute value. The specific functions and processing of the control unit 104 are also shown in step S310.

[0104] The control unit 104 is further configured to perform MTPA processing on the q-axis reference current to obtain a d-axis current, such as the d-axis current The specific functions and processing of the control unit 104 also refer to step S320.

[0105] The control unit 104 is further configured to compensate the d-axis current using the weak magnetic compensation current to obtain a weak magnetic current, such as a weak magnetic current The specific functions and processing of the control unit 104 also refer to step S330.

[0106] The control unit 104 is further configured to calculate the torque reference value and flux linkage reference value of the motor after performing out-of-control limiting and compensation processing on the weak magnetic current. The specific functions and processing of the control unit 104 are also shown in step S340.

[0107] Figure 7 The coordinate diagram of the current limit circle and the voltage limit ellipse. For a specific motor (such as a permanent magnet synchronous motor) control system, its parameters are fixed, so it has its corresponding voltage limit ellipse and current limit circle model. For the convenience of analysis, Figure 7 The figure shows that the two are placed in the same coordinate system. Figure 7 As shown in the figure, the current limit circle amplitude is a constant value, that is, I max , and the radius of the voltage limit ellipse decreases as the motor speed increases. Point C is the center of the voltage limit ellipse. The current value here is the characteristic current value I of the motor (such as permanent magnet synchronous motor) c . As the motor speed increases, the motor (such as a permanent magnet synchronous motor) control system enters a state of deep magnetic weakening area. When the motor (such as a permanent magnet synchronous motor) speed rises to the point where the voltage limit ellipse and the current limit circle are only tangent at point A, the motor (such as a permanent magnet synchronous motor) speed is ω1, and the motor (such as a permanent magnet synchronous motor) control system is in a critical state. When the motor (such as a permanent magnet synchronous motor) speed is further increased to ω2, the voltage limit ellipse is further reduced. At this time, there is no intersection between the current limit circle and the voltage limit ellipse. At this time, point A is always on the left side of the voltage limit ellipse. In this way, there will be a large error between the actual current of the motor (such as a permanent magnet synchronous motor) and the reference current of the given torque and flux generation module of the motor (such as a permanent magnet synchronous motor) control system. The calculated torque and flux reference values ​​are inaccurate. When the given torque and flux reference values ​​are inaccurate, the control of the motor (such as a permanent magnet synchronous motor) control system will be inaccurate or even out of control. Therefore, the above situation should be avoided in the actual control system.

[0108] In the scheme of the present invention, the problem of current runaway caused by excessive weak magnetic current in the weak magnetic speed-up device is taken into consideration, so it is necessary to limit it. Different from the weak magnetic control in the related scheme, in order to avoid the current runaway caused by the current not following in the deep weak magnetic area, the scheme of the present invention adopts a weak magnetic limiting device to prevent the d-axis current from appearing on the left side of the characteristic current, and at the same time adopts the segmented weak magnetic method, and the difference before and after the d-axis current is limited is used as the weak magnetic compensation value of the q-axis current, so as to realize the second step of weak magnetic and achieve the purpose of speed increase.

[0109] Figure 8 It is a structural schematic diagram of an embodiment of a reference torque and flux generation module. Figure 8The reference torque and flux generation module is shown in FIG. 1 , which is mainly composed of three parts: the weak magnetic compensation module, the loss of control limit and compensation module and the final torque flux calculation module. In the weak magnetic compensation module, the voltage limit value u max and the stator voltage amplitude u ref The absolute value of the comparison is passed through the PI controller to generate a weak magnetic compensation current q-axis reference current i q * After MTPA (maximum torque current ratio control) calculation, the d-axis current is obtained Through the weak magnetic compensation current After compensation, the weak magnetic current can be obtained At this time, the out-of-control limiting and compensation module is entered.

[0110] In some implementations, the control unit 104 calculates the torque reference value and the flux linkage reference value of the motor after performing out-of-control limiting and compensation processing on the weak magnetic current, including:

[0111] The control unit 104 is further configured to clamp the weak magnetic current to the characteristic current of the motor after performing voltage limit circle limiting processing, such as the characteristic current I c , recorded as the minimum value of the weak magnetic current, such as The specific functions and processing of the control unit 104 also refer to step S410.

[0112] The control unit 104 is further configured to use the difference between the weak magnetic current and the minimum value of the weak magnetic current as the compensation value of the q axis, such as Δi q The specific functions and processing of the control unit 104 can also be found in step S420.

[0113] The control unit 104 is further configured to further weaken the magnetic field of the magnetic field current to obtain a further magnetic field weakening current, that is, a second magnetic field weakening current. The specific functions and processing of the control unit 104 are also shown in step S430.

[0114] The control unit 104 is further configured to obtain the current value of the out-of-control limit and compensation after the minimum value of the weak magnetic current and the further weak magnetic current are limited by the current limit circle. The specific functions and processing of the control unit 104 are also shown in step S440.

[0115] The control unit 104 is further configured to use a preset torque flux calculation module to calculate the current value of the loss-of-control limit and compensation to obtain the torque reference value and flux reference value of the motor. The specific functions and processing of the control unit 104 are also shown in step S450.

[0116] See also Figure 8 In the example shown, in the out-of-control limiting and compensation module, the field weakening current After being limited, it is clamped at the characteristic current I c , which is recorded as As the speed increases, the weak magnetic current decreases to its minimum value. At this time, the d-axis current cannot change any more, and the q-axis current can be reversely compensated to continue with magnetic weakening. Figure 8 As shown in With the weak magnetic current after limiting Make a difference and get the compensation value Δi of the q axis q Since the d-axis current in weak magnetic control is always negative, Δi q is also a negative value, that is, further weak magnetic control is achieved by reducing the q-axis current value. c The device for limiting the d-axis current makes the current command of the motor (such as a permanent magnet synchronous motor) control system to the right of the characteristic current point throughout the whole process, that is, to ensure that the motor (such as a permanent magnet synchronous motor) control system will not be unstable. The characteristic current is an inherent parameter of the motor (such as a permanent magnet synchronous motor) system, which can be obtained by a variety of devices and will not be described here.

[0117] Depend on Figure 8 As shown in the example, the voltage and current in the control system of the motor (such as a permanent magnet synchronous motor) need to meet the corresponding voltage limit ellipse and current limit circle limits. The current value generated in the out-of-control limit and compensation module is input into the torque and flux calculation module to calculate the reference value T of the torque and flux. e * and ψ s * .

[0118] The control unit 104 is further configured to predict the torque and flux of the motor in a future set period according to the torque reference value and the flux reference value using a preset torque flux prediction model to obtain a predicted torque and a predicted flux. The specific functions and processing of the control unit 104 are also shown in step S230.

[0119] Considering the actual use characteristics of motors (such as permanent magnet synchronous motors), they are often required to operate in a wider range of speed regulation. As the speed of the motor (such as permanent magnet synchronous motor) increases, the back electromotive force of the motor (such as permanent magnet synchronous motor) will be limited by the DC side voltage of the inverter, so the predictive torque control device in the relevant scheme cannot achieve the purpose of speed expansion. In order to enable the motor (such as permanent magnet synchronous motor) to operate stably in a wider speed range, the motor system (such as permanent magnet synchronous motor system) needs to adopt a weak magnetic control device to achieve weak magnetic speed increase and widen its speed regulation range.

[0120] That is to say, as the motor speed increases, the predicted torque control device in the relevant scheme cannot meet its speed regulation requirements, so it is necessary to adopt weak magnetic field control to increase its operating speed through a weak magnetic field speed-up device. In the weak magnetic field control in the relevant scheme, if the given current is large and the motor system (such as a permanent magnet synchronous motor system) is in a deep weak magnetic field area, if the current trajectory planning is unreasonable, it is easy to cause the actual current to fail to follow the given current, that is, the current is out of control, which will also cause the motor system (permanent magnet synchronous motor system) to be unstable.

[0121] Considering that in the predictive torque control device, as the speed increases, the control system needs to enter the deep magnetic weakening area, and as the current vector moves on the current limit circle, the current is prone to not follow, resulting in system out of control or even a runaway situation. The solution of the present invention adopts a magnetic weakening control device in the model predictive torque control device, compares the equivalent synthesized stator voltage reference value with the inverter withstand voltage threshold, generates a magnetic weakening compensation current after passing through the PI regulator, compensates the d-axis current, and realizes magnetic weakening control.

[0122] In this way, compared with the model prediction torque control device in the related scheme, the scheme of the present invention adopts a weak magnetic speed-up device, which compares the stator voltage reference value synthesized by the torque and magnetic flux equivalent with the inverter withstand voltage threshold, and generates a weak magnetic compensation current after passing through the PI regulator (i.e., proportional-integral regulator) to compensate the d-axis current and realize weak magnetic control.

[0123] The control unit 104 is further configured to construct an equivalent stator voltage reference vector according to the predicted torque and the predicted flux, determine a target vector according to the constructed equivalent stator voltage reference vector, and control the motor according to the target vector. The specific functions and processing of the control unit 104 are also shown in step S130.

[0124] The solution of the present invention proposes a model predictive torque control method, that is, a method for suppressing weak magnetic field out of control based on model predictive torque control. A weak magnetic field control method is adopted in the model predictive torque control method, and the control method can realize weak magnetic field compensation by means of voltage signal feedback, and adopt a limiting method and a segmented weak magnetic field method to achieve the purpose of weak magnetic field speed increase, which can improve the control effect of predictive torque control of motors (such as permanent magnet synchronous motors).

[0125] In some implementations, the control unit 104 constructs an equivalent stator voltage reference vector according to the predicted torque and the predicted flux, and determines a target vector according to the constructed equivalent stator voltage reference vector, including:

[0126] The control unit 104 is further configured to calculate the predicted values ​​of the current d-axis current and q-axis current of the motor at the next sampling moment according to the three-phase stator current of the motor, that is, the d-axis current and q-axis current at the next sampling moment, such as i dq (k+1). The specific functions and processing of the control unit 104 also refer to step S510.

[0127] The control unit 104 is further configured to calculate the predicted values ​​of the torque and flux of the motor at the next sampling moment, that is, the torque and flux at the next sampling moment, according to the d-axis current and the q-axis current at the next sampling moment, such as T e (k+1) and ψ s (k+1); After performing beat compensation on the torque and flux at the next sampling moment, the predicted values ​​after the next two sampling moments are obtained, that is, the torque and flux at the next two sampling moments, such as T e (k+2) and ψ s (k+2). The specific functions and processing of the control unit 104 also refer to step S520.

[0128] The control unit 104 is further configured to integrate the torque and flux at the next two sampling moments into an error term between the basic voltage vector and the current stator voltage vector reference value according to the set voltage-current relationship, so as to construct an equivalent stator voltage reference vector. The specific functions and processing of the control unit 104 are also shown in step S530.

[0129] The control unit 104 is further configured to use the error term as a value function value for evaluating torque and flux control performance, substitute it into the basic voltage vector in the candidate vector set for rolling optimization calculation and evaluation, and select the basic voltage vector with the lowest error vector amplitude as the optimal basic voltage vector, i.e., the target vector. The specific functions and processing of the control unit 104 are also shown in step S540.

[0130] Considering that in the prediction torque control of permanent magnet synchronous motor in the related scheme, the value function is complex to construct, involves many controlled quantities, and the weight coefficient setting is complex. The scheme of the present invention adopts a new value function construction device to construct an equivalent stator voltage reference vector with predicted torque and flux, and judges the optimal vector by comparing the distance between the stator voltage reference vector and the basic voltage vector to control the motor (such as permanent magnet synchronous motor).

[0131] Thus, compared with the model prediction torque control device in the related schemes, the scheme of the present invention adopts a new value function construction device, which synthesizes the stator voltage reference vector by torque and magnetic flux equivalent, and judges the optimal vector by comparing the distance between the voltage reference vector and the basic voltage vector to control the motor (such as a permanent magnet synchronous motor).

[0132] Fig. 9 FIG. 1 is a schematic diagram of an overall control flow of an embodiment of a control device for a motor (such as a permanent magnet synchronous motor). Fig. 9 As shown, the motor encoder feeds back the motor speed ω r , with the given speed ω r * Comparison, after passing through the PI regulator, generates the q-axis reference current i q * , and then by Figure 8 The reference torque and flux generation module shown generates reference values ​​T of torque and flux. e * and ψ s * . Sample the three-phase current i from the motor system A,B,C , combined with the position signal θ output by the encoder r , after coordinate transformation, the current signal i in the rotating coordinate system is obtained d,q Considering the signal delay in the digital system, deadbeat compensation is introduced here to compensate the signal of one sampling cycle and obtain the current signal i after one cycle. d,q (k+1). According to the prediction model of torque and flux, the predicted value T of torque and flux after two cycles is obtained. e (k+2) and ψ d,q (k+2), these two predicted values ​​can be equivalently synthesized into the stator voltage vector u ref , analyze and compare the stator voltage vector u ref The error relationship between the stator voltage vector and the basic voltage vector can be used to obtain the optimal vector to act on the inverter and control the motor system. ref The absolute value is fed back to the weak magnetic field compensation module to generate weak magnetic field compensation current.

[0133] See also Fig. 9 In the example shown, the solution of the present invention provides a control device for a permanent magnet synchronous motor, more specifically a weak magnetic runaway suppression device based on model predictive torque control, comprising:

[0134] Step 1: First sample the three-phase stator current, and transform the current from the three-phase ABC stationary axis system to the dq rotating axis system through coordinate transformation to obtain i d and i q Through the Euler forward formula, the predicted values ​​i of the current d-axis current and q-axis current at the next sampling time are obtained. dq (k+1), expressed as:

[0135]

[0136] Step 2: According to the current idq (k+1) and the torque and flux equations, the predicted values ​​of torque and flux at the next sampling time T can be obtained. e (k+1) and ψ s (k+1), in order to compensate for the delay of the digital system, according to the deadbeat principle, the current reference value is equal to the predicted value at the next sampling moment. Combined with the aforementioned one-beat prediction control, the motor (such as a permanent magnet synchronous motor) can control the current value T of the control system. e * and ψ s * Equal to the predicted value T after two sampling moments e (k+2) and ψ s (k+2).

[0137] Step 3: The predicted values ​​of torque and flux T e (k+2) and ψ s (k+2), according to the voltage-current relationship, is integrated into the error term between the basic voltage vector and the current stator voltage vector reference value, which is represented by V err Indicates that V err =|u ref -V i |.

[0138] Among them, u ref is the predicted value of torque and flux T e (k+2) and ψ s (k+2) equivalent synthesized stator reference voltage vector, V i is the basic voltage vector, then V err That is, as the value function value for evaluating the torque and flux control performance, when selecting the basic voltage vector, it can be substituted into the basic voltage vector in the candidate vector set for rolling optimization calculation and evaluation to select the error vector V err The basic voltage vector with the lowest amplitude is the optimal basic voltage vector.

[0139] Step 4: When the speed is further increased, the motor (such as a permanent magnet synchronous motor) control system enters the weak magnetic field region, and the equivalent reference vector u ref The amplitude is taken and fed back to the weak magnetic module. After being compared with the maximum voltage threshold of the inverter, the weak magnetic compensation current is obtained through the PI regulator. The speed information fed back by the encoder is compared with the given speed, and then the PI regulator is used to obtain the q-axis current reference value. Then, the MTPA calculation is performed and the d-axis current after magnetic weakening is obtained in combination with the magnetic weakening compensation current. The limiting module limits the d-axis current according to the parameters of the motor (such as permanent magnet synchronous motor) control system, that is, the characteristic current I c It is limited, and the weak magnetic current is obtained after limiting The difference before and after the limit is used as the weak magnetic compensation value of the q-axis current, that is, the compensation value Δi q Since the d-axis current in weak magnetic control is always negative, Δi q It is also a negative value, that is, further weak magnetic control is achieved by reducing the q-axis current value, and the weak magnetic q-axis current is obtained.

[0140] Step 5. After obtaining the d-axis current and q-axis current after weak magnetic field, the d-axis current and q-axis current must meet the restrictions of the current limit circle. Then the reference values ​​of the torque and flux linkage can be calculated. The calculation formula for the electromagnetic torque of the permanent magnet synchronous motor is:

[0141]

[0142] Among them, according to the reference values ​​of torque and flux obtained in step 5, combined with the prediction and zero-beat calculation in step 2, a new round of torque and flux prediction values ​​can be obtained, and then the motor (such as permanent magnet synchronous motor) control system can be controlled.

[0143] Step 6. According to the calculation relationship between the motor stator current, torque and flux mentioned above, the flux expression is:

[0144]

[0145] in:

[0146]

[0147] In formula (4), when calculating the d-axis and q-axis flux linkages, the d-axis and q-axis current values ​​after magnetic weakening are used, and the d-axis current uses the magnetic weakening current after amplitude limiting. Figure 8 It is intuitively reflected in the structure.

[0148] The scheme of the present invention adopts an out-of-control limiting and compensation device in the weak magnetic speed-up link of the model predictive torque control, wherein the stator voltage feedback value of the weak magnetic compensation module is the stator voltage amplitude equivalent to the predicted torque and the predicted magnetic flux in the model predictive torque control. On the one hand, the equivalent stator voltage vector is used as a value function to screen the basic voltage vector for driving the motor system. On the other hand, its amplitude is taken as the voltage feedback value and fed back to the weak magnetic compensation module to perform weak magnetic compensation on the d-axis current. After the weak magnetic compensation of the d-axis current, in order to limit it from being too large, a device using characteristic current limiting is used to strictly limit the d-axis current value to the right side of the characteristic current value, so as to ensure the stability of the system. The difference before and after the limiting is used as the weak magnetic compensation value of the q-axis current to achieve the second step of weak magnetic and weak magnetic speed-up.

[0149] Since the processing and functions implemented by the device of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments, and no further elaboration will be made here.

[0150] After a large number of experimental verifications, the technical solution of the present invention is adopted to simplify the value function construction process by constructing an equivalent stator voltage reference vector based on predicted torque and magnetic flux, judging the optimal vector by comparing the distance between the stator voltage reference vector and the basic voltage vector, and performing weak magnetic limitation to control the motor (such as a permanent magnet synchronous motor).

[0151] According to an embodiment of the present invention, a motor corresponding to a control device of the motor is also provided. The motor may include: the control device of the motor described above.

[0152] Since the processing and functions implemented by the motor of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned device, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0153] A large number of experiments have verified that the technical solution of the present invention is adopted, by constructing a stator voltage reference vector equivalent to the predicted torque and magnetic flux, judging the optimal vector by comparing the distance between the stator voltage reference vector and the basic voltage vector, and performing weak magnetic limitation to control the motor (such as a permanent magnet synchronous motor), so as to achieve weak magnetic speed increase.

[0154] According to an embodiment of the present invention, a storage medium corresponding to the motor control method is also provided, wherein the storage medium includes a stored program, wherein when the program is executed, the device where the storage medium is located is controlled to execute the motor control method described above.

[0155] Since the processing and functions implemented by the storage medium of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments, and no further elaboration will be made here.

[0156] A large number of experiments have verified that the technical solution of the present invention is adopted, by constructing a stator voltage reference vector equivalent to the predicted torque and magnetic flux, judging the optimal vector by comparing the distance between the stator voltage reference vector and the basic voltage vector, and performing weak magnetic limitation to control the motor (such as a permanent magnet synchronous motor), so as to avoid current runaway caused by excessive weak magnetic current.

[0157] According to an embodiment of the present invention, a processor corresponding to the motor control method is also provided, and the processor is used to run a program, wherein the motor control method described above is executed when the program is run.

[0158] Since the processing and functions implemented by the processor of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0159] After a large number of experimental verifications, the technical solution of the present invention is adopted, by constructing an equivalent stator voltage reference vector based on predicted torque and magnetic flux, judging the optimal vector by comparing the distance between the stator voltage reference vector and the basic voltage vector, and performing weak magnetic limitation, to control the motor (such as a permanent magnet synchronous motor) and improve the control accuracy of the motor (such as a permanent magnet synchronous motor).

[0160] In summary, it is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0161] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A method for controlling a motor, characterized in that: include: Obtaining the current speed and given speed of the motor; Obtaining a voltage limit value of an inverter in the motor power supply, and obtaining a stator voltage amplitude of the motor; as well as, According to the current speed, the given speed, the voltage limit value and the stator voltage amplitude, weak magnetic field compensation and amplitude limiting processing are performed, and then the torque and flux of the motor in a future set period are predicted to obtain predicted torque and predicted flux; constructing an equivalent stator voltage reference vector according to the predicted torque and the predicted flux, and determining a target vector according to the constructed equivalent stator voltage reference vector to control the motor according to the target vector; According to the current speed, the given speed, the voltage limit value and the stator voltage amplitude, weak magnetic compensation and amplitude limiting processing are performed, and then the torque and flux of the motor in a future set period are predicted to obtain the predicted torque and predicted flux, including: The difference between the current speed and the given speed is processed by PI to obtain a q-axis reference current of the motor; According to the voltage limit value and the stator voltage amplitude, the q-axis reference current is subjected to magnetic weakening compensation and out-of-control limiting and compensation processing, and the torque reference value and flux linkage reference value of the motor are calculated; wherein, in the out-of-control limiting and compensation module, the magnetic weakening current i d * _fw After being limited, it is clamped at the characteristic current I c , denoted as i d * _fw_lim ; As the speed increases, the weak magnetic current decreases to its minimum value i d * _fw_lim At this time, the d-axis current no longer changes, and the q-axis current is reversely compensated to continue the weak magnetic field; the weak magnetic field current i d * _fw and the weak magnetic current i after limiting d * _fw_lim Make a difference and get the compensation value Δi of the q axis q ; According to the torque reference value and the flux linkage reference value, a preset torque flux linkage prediction model is used to predict the torque and flux linkage of the motor in a future set period to obtain a predicted torque and a predicted flux linkage.

2. The motor control method according to claim 1, characterized in that: According to the voltage limit value and the stator voltage amplitude, after performing magnetic field weakening compensation and out-of-control limiting and compensation processing on the q-axis reference current, a torque reference value and a flux linkage reference value of the motor are calculated, including: After PI processing is performed on the difference between the voltage limit value and the stator voltage amplitude, a weak magnetic compensation current is obtained; wherein the stator voltage amplitude is an absolute value; After performing MTPA processing on the q-axis reference current, a d-axis current is obtained; Using the weak magnetic field compensation current to compensate the d-axis current to obtain a weak magnetic field current; After the out-of-control limiting and compensation processing is performed on the weak magnetic current, the torque reference value and the flux linkage reference value of the motor are calculated.

3. The motor control method according to claim 2, characterized in that: After the weak magnetic current is subjected to out-of-control limiting and compensation processing, a torque reference value and a flux linkage reference value of the motor are calculated, including: After the weak magnetic current is subjected to voltage limit circle limiting processing, the characteristic current clamped at the motor is recorded as the minimum value of the weak magnetic current; Using the difference between the weak magnetic current and the minimum value of the weak magnetic current as a compensation value of the q-axis; After further weakening the magnetic field of the magnetic field weakening current, a further magnetic field weakening current is obtained; After the minimum value of the weak magnetic current and the further weak magnetic current are limited by the current limit circle, the current value of out-of-control limiting and compensation is obtained; The preset torque flux calculation module is used to calculate the current value of the out-of-control limiting and compensation to obtain the torque reference value and flux reference value of the motor.

4. The method for controlling a motor according to any one of claims 1 to 3, characterized in that: According to the predicted torque and the predicted flux, an equivalent stator voltage reference vector is constructed, and a target vector is determined according to the constructed equivalent stator voltage reference vector, including: According to the three-phase stator current of the motor, the predicted values ​​of the current d-axis current and q-axis current of the motor at the next sampling moment are calculated, that is, the d-axis current and q-axis current at the next sampling moment; According to the d-axis current and the q-axis current at the next sampling moment, the predicted values ​​of the torque and flux of the motor at the next sampling moment, i.e., the torque and flux at the next sampling moment, are calculated; after performing beat compensation on the torque and flux at the next sampling moment, the predicted values ​​after the next two sampling moments, i.e., the torque and flux at the next two sampling moments, are obtained; Integrate the torque and flux at the next two sampling moments into an error term between the basic voltage vector and the current stator voltage vector reference value according to a set voltage-current relationship; The error term is used as the value function value for evaluating the torque and flux control performance, and is substituted into the basic voltage vector in the candidate vector set for rolling optimization calculation and evaluation, and the basic voltage vector with the lowest error vector amplitude is selected as the optimal basic voltage vector, i.e., the target vector.

5. A motor control device, characterized in that: include: An acquisition unit, configured to acquire a current rotation speed and a given rotation speed of the motor; Obtaining a voltage limit value of an inverter in the motor power supply, and obtaining a stator voltage amplitude of the motor; as well as, A control unit is configured to perform magnetic field weakening compensation and amplitude limiting processing according to the current speed, the given speed, the voltage limit value and the stator voltage amplitude, and then predict the torque and flux of the motor in a future set period to obtain a predicted torque and a predicted flux; The control unit is further configured to construct an equivalent stator voltage reference vector according to the predicted torque and the predicted flux, determine a target vector according to the constructed equivalent stator voltage reference vector, and control the motor according to the target vector; The control unit performs magnetic field weakening compensation and amplitude limiting processing according to the current speed, the given speed, the voltage limit value and the stator voltage amplitude, and then predicts the torque and flux of the motor in a future set period to obtain the predicted torque and predicted flux, including: The difference between the current speed and the given speed is processed by PI to obtain a q-axis reference current of the motor; According to the voltage limit value and the stator voltage amplitude, the q-axis reference current is subjected to magnetic weakening compensation and out-of-control limiting and compensation processing, and the torque reference value and flux linkage reference value of the motor are calculated; wherein, in the out-of-control limiting and compensation module, the magnetic weakening current i d * _fw After being limited, it is clamped at the characteristic current I c , denoted as i d * _fw_lim ; As the speed increases, the weak magnetic current decreases to its minimum value i d * _fw_lim At this time, the d-axis current no longer changes, and the q-axis current is reversely compensated to continue the weak magnetic field; the weak magnetic field current i d * _fw and the weak magnetic current i after limiting d * _fw_lim Make a difference and get the compensation value Δi of the q axis q ; According to the torque reference value and the flux linkage reference value, a preset torque flux linkage prediction model is used to predict the torque and flux linkage of the motor in a future set period to obtain a predicted torque and a predicted flux linkage.

6. The motor control device according to claim 5, characterized in that: The control unit calculates the torque reference value and flux linkage reference value of the motor after performing magnetic weakening compensation and out-of-control limiting and compensation processing on the q-axis reference current according to the voltage limit value and the stator voltage amplitude, including: After PI processing is performed on the difference between the voltage limit value and the stator voltage amplitude, a weak magnetic compensation current is obtained; wherein the stator voltage amplitude is an absolute value; After performing MTPA processing on the q-axis reference current, a d-axis current is obtained; Using the weak magnetic field compensation current to compensate the d-axis current to obtain a weak magnetic field current; After the weak magnetic current is subjected to out-of-control limiting and compensation processing, a torque reference value and a flux linkage reference value of the motor are calculated and obtained.

7. The control device for a motor according to claim 6, characterized in that: The control unit calculates a torque reference value and a flux linkage reference value of the motor after performing out-of-control limiting and compensation processing on the weak magnetic current, including: After the weak magnetic current is subjected to voltage limit circle limiting processing, the characteristic current clamped at the motor is recorded as the minimum value of the weak magnetic current; Using the difference between the weak magnetic current and the minimum value of the weak magnetic current as a compensation value of the q-axis; After further weakening the magnetic field of the magnetic field weakening current, a further magnetic field weakening current is obtained; After the minimum value of the weak magnetic current and the further weak magnetic current are limited by the current limit circle, the current value of out-of-control limiting and compensation is obtained; The preset torque flux calculation module is used to calculate the current value of the out-of-control limiting and compensation to obtain the torque reference value and flux reference value of the motor.

8. The control device for a motor according to any one of claims 5 to 7, characterized in that: The control unit constructs an equivalent stator voltage reference vector according to the predicted torque and the predicted flux linkage, and determines a target vector according to the constructed equivalent stator voltage reference vector, including: According to the three-phase stator current of the motor, the predicted values ​​of the current d-axis current and q-axis current of the motor at the next sampling moment are calculated, that is, the d-axis current and q-axis current at the next sampling moment; According to the d-axis current and the q-axis current at the next sampling moment, the predicted values ​​of the torque and flux of the motor at the next sampling moment, i.e., the torque and flux at the next sampling moment, are calculated; after performing beat compensation on the torque and flux at the next sampling moment, the predicted values ​​after the next two sampling moments, i.e., the torque and flux at the next two sampling moments, are obtained; Integrate the torque and flux at the next two sampling moments into an error term between the basic voltage vector and the current stator voltage vector reference value according to a set voltage-current relationship; The error term is used as the value function value for evaluating the torque and flux control performance, and is substituted into the basic voltage vector in the candidate vector set for rolling optimization calculation and evaluation, and the basic voltage vector with the lowest error vector amplitude is selected as the optimal basic voltage vector, i.e., the target vector.

9. A motor, characterized in that: include: A control device for an electric motor as claimed in any one of claims 5 to 8.

10. A storage medium, characterized in that: The storage medium includes a stored program, wherein when the program is executed, the device where the storage medium is located is controlled to execute the motor control method according to any one of claims 1 to 4.

11. A processor, characterized in that: The processor is used to run a program, wherein the program executes the motor control method according to any one of claims 1 to 4 when running.

Images