A Method for Suppressing Torque Ripple of Electromechanical Drive Motors Based on Number Field Control

Abstract

The present application proposes a method for suppressing torque ripple of an electromechanical drive motor based on number field control, belonging to the technical field of motor control. The method includes the following steps: constructing a look-up table; calculating the excitation phase torque and the demagnetization phase torque by using the look-up table, and constructing a torque distribution function; predicting the phase flux linkage values and the rotor positions at all times starting from the next moment respectively, and calculating the predicted values of the phase currents at the corresponding times; calculating the differences between the predicted values of the phase currents and the actual values of the phase currents at each time respectively to obtain the phase current error values at the corresponding times, and obtaining the phase current compensation values at the corresponding times through a feedforward neural network respectively; using the predicted values of the phase currents and the phase current compensation values at each time to obtain the torque values at the corresponding times in the look-up table, thereby constructing the cost function at each time, and respectively finding and using the switching states of all the cost functions to achieve the purpose of suppressing torque ripple. The present application can effectively reduce torque ripple while reducing copper loss.

Description

Technical Field

[0001] The present application relates to the field of motor control technology, and in particular to a method for suppressing torque pulsation of an electromechanical drive motor based on digital domain control. Background Art

[0002] As the core component of servo systems, actuators and speed regulators, electromechanical drive motors play a key role in many application fields such as manned spaceflight, hypersonic vehicles and space stations, and have far-reaching significance for the sustainable development of the national economy and the successful implementation of major projects. In order to meet the complex and changing working environment, electromechanical drive motors must have excellent performance including high speed, high torque, low torque pulsation, high efficiency, good electromagnetic compatibility and long life to meet different environmental requirements.

[0003] However, the existing electromechanical drive motors have the following disadvantages: First, under wide operating conditions, the high saturation phenomenon of the electromagnetic field will seriously affect the performance of the electromechanical drive motor; Second, the controller will generate harmonic currents during the switching process, and these harmonic currents will have a negative impact on the electromechanical drive motor and other equipment, resulting in reduced work efficiency; Third, the electromechanical drive motor generally adopts a double-pole structure design with intermittent working characteristics. Therefore, during the operation of the electromechanical drive motor, a large torque pulsation will be generated, which affects the stability of the electromechanical drive motor. In order to overcome the various defects of the above-mentioned electromechanical drive motors, the strategy of planning the current waveform is generally used to suppress the torque pulsation of the electromechanical drive motor. However, this strategy has the following disadvantages:

[0004] First, this strategy loses time information when performing pure frequency domain analysis of the electromagnetic field, and thus cannot reflect the digital domain characteristic signals of the drive control, resulting in excessive torque pulsation of the electromechanical drive motor;

[0005] Secondly, when this strategy is used to suppress the torque pulsation of the electromechanical drive motor, the operating efficiency of the electromechanical drive motor is affected due to the high copper loss.

[0006] Therefore, it is necessary to propose a solution to improve one or more problems existing in the above-mentioned related technical solutions.

[0007] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present application, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0008] The present application provides a method for suppressing torque pulsation of an electromechanical drive motor based on digital domain control, comprising the following steps:

[0009] A current-flux-rotor position lookup table and a current-torque-rotor position lookup table of the electromechanical drive motor are constructed based on a feedforward neural network, wherein the current-flux-rotor position lookup table includes the rotor position at all times and the phase flux value corresponding to the phase current value, and the current-torque-rotor position lookup table includes the rotor position at all times and the torque value corresponding to the phase current value;

[0010] Calculating the excitation phase torque and the demagnetization phase torque in sequence by using the current-flux-rotor position lookup table and the current-torque-rotor position lookup table, and constructing a torque allocation function by using the excitation phase torque and the demagnetization phase torque;

[0011] Discretizing the voltage balance equation, respectively predicting the phase flux linkage values ​​and the rotor positions at all moments from the next moment, and calculating the phase current prediction values ​​at the corresponding moment according to the predicted phase flux linkage prediction values ​​and the rotor prediction positions at all moments;

[0012] The difference between the predicted value of the phase current and the actual value of the phase current at each moment is calculated respectively to obtain the phase current error value at the corresponding moment, the phase current error values ​​at the previous moments are input into the feedforward neural network respectively, and the phase current compensation values ​​at the corresponding moments are obtained respectively using the output results of the feedforward neural network;

[0013] Using the phase current prediction value and the phase current compensation value at each moment, respectively obtain the torque value at the corresponding moment in the current-torque-rotor position lookup table;

[0014] The torque values ​​at all moments are used to construct cost functions at corresponding moments respectively, and the switching states when the cost function at each moment is closest to the torque distribution function are found respectively, and the switching states at all moments are used to control the electromechanical drive motor, thereby suppressing torque pulsation.

[0015] In an exemplary embodiment of the present application, the feedforward neural network is a back-propagation neural network.

[0016] In an exemplary embodiment of the present application, the steps of using the current-flux-rotor position lookup table and the current-torque-rotor position lookup table to sequentially calculate the excitation phase torque and the demagnetization phase torque, and using the excitation phase torque and the demagnetization phase torque to construct a torque allocation function include:

[0017] Calculating a commutation overlap angle according to relevant parameters of the electromechanical drive motor;

[0018] Using the torque value and the rotor position at the current moment, sequentially searching for the corresponding phase flux value in the current-torque-rotor position lookup table and the current-flux-rotor position lookup table;

[0019] Calculating the excitation phase flux using the phase flux value and the rotor position at the current moment, and sequentially searching for the corresponding excitation phase torque using the current-flux-rotor position lookup table and the current-torque-rotor position lookup table;

[0020] Calculating the demagnetization phase torque using the excitation phase torque;

[0021] The torque distribution function is constructed using the excitation phase torque and the demagnetization phase torque.

[0022] In an exemplary embodiment of the present application, the expression of the commutation overlap angle is:

[0023] (1)

[0024] in, It indicates the angle of the overlapping part of the two phases when the two adjacent phases of the electromechanical drive motor are switching the phase current, that is, the commutation overlap angle. represents the rotor pole pitch of the electromechanical drive motor, represents the stator pole arc of the electromechanical drive motor, Represents the rotor pole arc of an electromechanical drive motor;

[0025] The expression of the excitation phase flux is:

[0026] (2)

[0027] in, represents the excitation phase flux, It represents the slope of the excitation phase flux, , represents the reference phase flux, represents the opening angle, Indicates the rotor position at the current moment.

[0028] In an exemplary embodiment of the present application, the expression of the excitation phase torque is:

[0029] (3)

[0030] in, represents the excitation phase torque, Indicates about The function of ;

[0031] The expression of the demagnetization phase torque is:

[0032] (4)

[0033] in, represents the demagnetization phase torque, Indicates the load torque of the electromechanical drive motor;

[0034] The expression of the torque distribution function is:

[0035] (5)

[0036] in, Indicates the rotor position The corresponding torque distribution function is: represents the cut-off angle, represents the rotor period angle.

[0037] In an exemplary embodiment of the present application, the expression of the phase flux prediction value is:

[0038] ψ ph k +1 = ψ ph k + T s [ u ph k - R ph i ph ( k )] (6)

[0039] in, Indicates The predicted value of phase flux at time Indicates The phase flux value at the moment, represents the sampling step length, Indicates The phase voltage value at the moment, Indicates the resistance value of the phase resistor, Indicates Phase current value at the moment;

[0040] The expression of the predicted rotor position is:

[0041] (7)

[0042] in, Indicates The predicted rotor position at time , Indicates The rotor position at time, Indicates The speed of the electromechanical drive motor at that moment.

[0043] In an exemplary embodiment of the present application, the expression of the phase current prediction value is:

[0044] i ph k +1 = i [ ψ ph k +1 , θ ph k +1 ] (8)

[0045] in, Indicates The predicted phase current value at time i [ ψ ph k +1 , θ ph k +1 ] Represents the corresponding phase current value in the current-flux-rotor position lookup table.

[0046] In an exemplary embodiment of the present application, the steps of respectively calculating the difference between the predicted value of the phase current and the actual value of the phase current at each moment to obtain the phase current error value at the corresponding moment, respectively inputting the phase current error values ​​at the previous moments into the feedforward neural network, and respectively obtaining the phase current compensation values ​​at the corresponding moments using the output results of the feedforward neural network include:

[0047] The phase current error values ​​at the previous several moments are respectively input into the feedforward neural network, and by adjusting the weights of the nodes between the multiple neurons, the output result of the feedforward neural network is made close to the actual phase current error value of the electromechanical drive motor, and the phase current compensation value at the corresponding moment is calculated by using the actual phase current error value at each moment;

[0048] The expression of the phase current compensation value is:

[0049] (9)

[0050] in, Indicates Phase current compensation value at time Indicates The actual error value of the phase current at the moment, Indicates The predicted phase current at time.

[0051] In an exemplary embodiment of the present application, the expression of the torque value is:

[0052] (10)

[0053] in, Indicates The torque value at the moment, Represents the corresponding torque value in the current-torque-rotor position lookup table, Indicates The predicted rotor position at time.

[0054] In an exemplary embodiment of the present application, the step of using the torque values ​​at all times to construct the cost functions at the corresponding times, and finding the switch state when the cost function at each time is closest to the torque distribution function, and using the switch state at all times to control the electromechanical drive motor, thereby suppressing torque pulsation includes:

[0055] Constructing the cost functions at all moments respectively, and finding the switch state when the cost function at each moment is closest to the torque distribution function respectively;

[0056] Controlling the electromechanical drive motor using the switch state at all times, and calculating the minimum torque pulsation in the control process at each moment, so as to suppress the torque pulsation;

[0057] The expression of the cost function is:

[0058] H = α [ ∑ x =1 n T share - ∑ x =1 n T p ( k +1)] 2 + β ∑ x =1 n [ i p k +1 ] 2 (11)

[0059] in, represents the cost function, represents the weight coefficient of torque ripple in the cost function, represents the weight coefficient of copper loss, Indicates the electromechanical drive motor Mutually, represents the number of phases of the electromechanical drive motor, represents the torque distribution function, Indicates The torque value at the moment, Indicates Phase current compensation value at the moment.

[0060] Beneficial effects:

[0061] The present application provides a method for suppressing torque pulsation of an electromechanical drive motor based on digital domain control, which has at least the following beneficial effects:

[0062] (1) The present application constructs a torque allocation function by using a current-flux-rotor position lookup table and a current-torque-rotor position lookup table; calculates a phase current error value by using a phase current prediction value and a phase current actual value, obtains a corresponding phase current compensation value in a feedforward neural network by using the phase current error value, and thereby finds a corresponding torque value; constructs a cost function by using the torque value, and finds the switching state when the cost function is close to the torque allocation function, thereby suppressing the torque pulsation of the motor drive motor, solving the problem that information is lost in pure frequency domain analysis of the electromagnetic field and the number domain characteristic signal of the drive control cannot be reflected, thereby improving the adaptability of the electromechanical drive motor to the signal;

[0063] (2) The present application utilizes the torque values ​​at all times to construct the cost functions at the corresponding times, thereby obtaining the optimal voltage vector control power converter, which effectively reduces the torque pulsation while reducing the copper loss, thereby improving the operating efficiency and performance of the electromechanical drive motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0065] Figure 1 A schematic diagram showing the steps of a method for suppressing torque pulsation of an electromechanical drive motor based on digital domain control in an exemplary embodiment of the present application;

[0066] Figure 2 A schematic flow chart showing a method for suppressing torque pulsation of an electromechanical drive motor based on digital domain control in an exemplary embodiment of the present application is shown;

[0067] Figure 3 A schematic diagram showing a comparison between a method for suppressing torque pulsation based on number domain control of the present application and a method for suppressing torque pulsation based on number domain control of the present application in an exemplary embodiment of the present application;

[0068] Figure 4 A schematic diagram showing the effect of using a particle swarm algorithm to perform single-objective optimization on phase current in an exemplary embodiment of the present application;

[0069] Figure 5 A schematic diagram showing the effect of using a particle swarm algorithm to perform single-objective optimization on torque ripple in an exemplary embodiment of the present application;

[0070] Figure 6 A schematic diagram showing the effect of using a particle swarm algorithm to perform multi-objective optimization in an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0071] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more comprehensive and complete and fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0072] In addition, the accompanying drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0073] This example embodiment provides a method for suppressing torque pulsation of an electromechanical drive motor based on digital domain control, such as Figure 1 and Figure 2 As shown, the method may include the following steps:

[0074] Step S101: constructing a current-flux-rotor position lookup table and a current-torque-rotor position lookup table of the electromechanical drive motor based on a feedforward neural network, wherein the current-flux-rotor position lookup table includes phase flux values ​​corresponding to rotor positions and phase current values ​​at all times, and the current-torque-rotor position lookup table includes torque values ​​corresponding to rotor positions and phase current values ​​at all times;

[0075] Step S102: using the current-flux-rotor position lookup table and the current-torque-rotor position lookup table, the excitation phase torque and the demagnetization phase torque are calculated in sequence, and the torque allocation function is constructed using the excitation phase torque and the demagnetization phase torque;

[0076] Step S103: discretizing the voltage balance equation, respectively predicting the phase flux linkage values ​​and rotor positions at all times from the next moment, and calculating the phase current prediction value at the corresponding moment according to the predicted phase flux linkage prediction values ​​and rotor prediction positions at all times;

[0077] Step S104: Calculate the difference between the predicted phase current value and the actual phase current value at each moment to obtain the phase current error value at the corresponding moment, input the phase current error values ​​at the previous moments into the feedforward neural network, and use the output results of the feedforward neural network to obtain the phase current compensation values ​​at the corresponding moments;

[0078] Step S105: using the phase current prediction value and the phase current compensation value at each moment, respectively obtaining the torque value at the corresponding moment in the current-torque-rotor position lookup table;

[0079] Step S106: Use the torque values ​​at all moments to construct the cost functions at the corresponding moments, and find the switching state when the cost function at each moment is closest to the torque distribution function, and use the switching state at all moments to control the electromechanical drive motor to suppress torque pulsation.

[0080] The embodiment of the present application proposes a method for suppressing torque pulsation of an electromechanical drive motor based on digital domain control, which has at least the following beneficial effects:

[0081] (1) The present application constructs a torque allocation function by using a current-flux-rotor position lookup table and a current-torque-rotor position lookup table; calculates a phase current error value by using a phase current prediction value and a phase current actual value, obtains a corresponding phase current compensation value in a feedforward neural network by using the phase current error value, and thereby finds a corresponding torque value; constructs a cost function by using the torque value, and finds the switching state when the cost function is close to the torque allocation function, thereby suppressing the torque pulsation of the motor drive motor, solving the problem that information is lost in pure frequency domain analysis of the electromagnetic field and the number domain characteristic signal of the drive control cannot be reflected, thereby improving the adaptability of the electromechanical drive motor to the signal;

[0082] (2) The present application utilizes the torque values ​​at all times to construct the cost functions at the corresponding times, thereby obtaining the optimal voltage vector control power converter, which effectively reduces the torque pulsation while reducing the copper loss, thereby improving the operating efficiency and performance of the electromechanical drive motor.

[0083] Next, a method for suppressing torque pulsation of an electromechanical drive motor based on number domain control proposed in this example embodiment will be described in more detail.

[0084] In step S101 of the present embodiment, a current-flux-rotor position lookup table and a current-torque-rotor position lookup table of the electromechanical drive motor are constructed based on a feedforward neural network. The current-flux-rotor position lookup table includes the phase flux values ​​corresponding to the rotor positions and phase current values ​​at all times, and the current-torque-rotor position lookup table includes the torque values ​​corresponding to the rotor positions and phase current values ​​at all times.

[0085] Furthermore, in this embodiment, the feedforward neural network is preferably a back propagation (BP) neural network, that is, a BP neural network, which is a multi-layer feedforward neural network trained according to an error back propagation algorithm.

[0086] In step S102 of this embodiment, the excitation phase torque and the demagnetization phase torque are calculated in sequence using the current-flux-rotor position lookup table and the current-torque-rotor position lookup table, and the torque allocation function is constructed using the excitation phase torque and the demagnetization phase torque. Step S102 of this embodiment may include the following sub-steps:

[0087] Sub-step S1021: Calculate the commutation overlap angle according to relevant parameters of the electromechanical drive motor.

[0088] Furthermore, the expression of the commutation overlap angle is:

[0089] (1)

[0090] in, It indicates the angle of the overlapping part of the two phases when the two adjacent phases of the electromechanical drive motor are switching the phase current, that is, the commutation overlap angle. represents the rotor pole pitch of the electromechanical drive motor, represents the stator pole arc of the electromechanical drive motor, Represents the rotor pole arc of an electromechanical drive motor.

[0091] In this embodiment, a 1.65KW three-phase 12 / 8 electromechanical drive motor is selected, and the speed is 1000r / min. The rotor pole pitch of the three-phase 12 / 8 electromechanical drive motor is 45°, stator pole arc The rotor pole arc is 12.8° is 14.7°. Therefore, the commutation overlap angle is:

[0092]

[0093] Sub-step S1022: using the torque value and rotor position at the current moment, search for the corresponding phase flux value in the current-torque-rotor position lookup table and the current-flux-rotor position lookup table in turn.

[0094] In this embodiment, the load torque of the electromechanical drive motor is is 1Nm, so the reference phase flux is found It is 0.0036Wb.

[0095] Sub-step S1023: Calculate the excitation phase flux using the current phase flux value and rotor position, and sequentially use the current-flux-rotor position lookup table and the current-torque-rotor position lookup table to find the corresponding excitation phase torque.

[0096] Furthermore, the expression of the excitation phase flux is:

[0097] (2)

[0098] in, represents the excitation phase flux, It represents the slope of the excitation phase flux, , represents the reference phase flux, represents the opening angle, Indicates the rotor position at the current moment.

[0099] In this embodiment, .

[0100] Furthermore, the expression of the excitation phase torque is:

[0101] (3)

[0102] in, represents the excitation phase torque, Indicates about The function of .

[0103] Sub-step S1024: Calculate the demagnetization phase torque using the excitation phase torque.

[0104] Furthermore, the expression of the demagnetization phase torque is:

[0105] (4)

[0106] in, represents the demagnetization phase torque, Represents the load torque of the electromechanical drive motor.

[0107] Sub-step S1025: constructing a torque distribution function using the excitation phase torque and the demagnetization phase torque.

[0108] Furthermore, the expression of the torque distribution function is:

[0109] (5)

[0110] in, Indicates the rotor position The corresponding torque distribution function is: represents the cut-off angle, represents the rotor period angle.

[0111] In step S103 of this embodiment, the voltage balance equation is discretized, and the phase flux values ​​and rotor positions at all times from the next moment are predicted respectively, and the phase current prediction value at the corresponding moment is calculated based on the predicted phase flux prediction values ​​and rotor prediction positions at all times.

[0112] Furthermore, the voltage balance equation is expressed as:

[0113] ψ ph k = ∫ [ u ph ( k ) - R ph i ph ( k )] dt

[0114] in, Indicates Phase flux value at the moment.

[0115] Furthermore, the expression of the phase flux prediction value is:

[0116] ψ ph k +1 = ψ ph k + T s [ u ph k - R ph i ph ( k )] (6)

[0117] in, Indicates The predicted value of phase flux at time Indicates The phase flux value at the moment, represents the sampling step length, Indicates The phase voltage value at the moment, Indicates the resistance value of the phase resistor, Indicates Phase current value at the moment.

[0118] Furthermore, in the phase-changing conduction region, only the switching states of the two phases being switched are predicted. In order to avoid generating negative torque, the switching states of the remaining phases are as shown in Table 1 below. The nine switching states in the phase-changing conduction region are as shown in Table 1 below:

[0119] Table 1: Nine switching states in the commutation conduction region

[0120]

[0121] It can be seen from Table 1 that in this embodiment, a three-phase (i.e., phase A, phase B, and phase C) 12 / 8 electromechanical drive motor is used as an example for explanation. Each phase includes three states: excitation is represented by "1", freewheeling is represented by "0", and demagnetization is represented by "-1".

[0122] In the single-phase conduction area, only the conduction phase has three states: "1", "0" and "-1", and the other two phases are both in the "-1" state, so there are three states in the single-phase conduction area.

[0123] In the commutation conduction region, the two phases of commutation have three states of "1", "0" and "-1", and the demagnetization phase is in the "-1" state, so the commutation conduction region has a total of 3×3=9 states.

[0124] The expression for the predicted rotor position is:

[0125] (7)

[0126] in, Indicates The predicted rotor position at time , Indicates The rotor position at time, Indicates The speed of the electromechanical drive motor at that moment.

[0127] Furthermore, the expression of the phase current prediction value is:

[0128] i ph k +1 = i [ ψ ph k +1 , θ ph k +1 ] (8)

[0129] in, Indicates The predicted phase current value at time i [ ψ ph k +1 , θ ph k +1 ] Represents the corresponding phase current value in the current-flux-rotor position lookup table.

[0130] In step S104 of this embodiment, the difference between the predicted phase current value and the actual phase current value at each moment is calculated to obtain the phase current error value at the corresponding moment, the phase current error values ​​at the previous moments are respectively input into the feedforward neural network, and the output results of the feedforward neural network are used to obtain the phase current compensation values ​​at the corresponding moments. Step S104 of this embodiment may include:

[0131] The phase current error values ​​at several previous moments are respectively input into the feedforward neural network, and by adjusting the weights of the nodes between multiple neurons, the output result of the feedforward neural network is made close to the actual error value of the phase current of the electromechanical drive motor, and the actual error value of the phase current at each moment is used to calculate the phase current compensation value at the corresponding moment.

[0132] Furthermore, the expression of the phase current compensation value is:

[0133] (9)

[0134] in, Indicates Phase current compensation value at time Indicates The actual error value of the phase current at the moment, Indicates The predicted phase current at time.

[0135] In step S105 of this embodiment, the torque value at the corresponding moment is obtained in the current-torque-rotor position lookup table by using the phase current prediction value and the phase current compensation value at each moment.

[0136] Furthermore, the expression of torque value is:

[0137] (10)

[0138] in, Indicates The torque value at the moment, Represents the corresponding torque value in the current-torque-rotor position lookup table, Indicates The predicted rotor position at time.

[0139] In step S106 of this embodiment, Figure 3 As shown, the cost functions of the corresponding moments are constructed using the torque values ​​at all moments, and the switch states when the cost functions at each moment are closest to the torque distribution function are found, and the switch states at all moments are used to control the electromechanical drive motor, thereby suppressing torque pulsation. In this embodiment, step S106 may include the following sub-steps:

[0140] Furthermore, the cost function is expressed as:

[0141] H = α [ ∑ x =1 n T share - ∑ x =1 n T p ( k +1)] 2 + β ∑ x =1 n [ k +1 ] 2 (11)

[0142] in, represents the cost function, represents the weight coefficient of torque ripple in the cost function, represents the weight coefficient of copper loss, Indicates the electromechanical drive motor Mutually, represents the number of phases of the electromechanical drive motor, represents the torque distribution function, Indicates The torque value at the moment, Indicates Phase current compensation value at the moment.

[0143] Figure 3 In the screening, the main goal is to suppress torque pulsation by using the cost function, and the secondary goal is to reduce copper loss. Figure 3 The torque without new digital domain control means that the torque pulsation suppression method based on digital domain control of this application is not adopted, and the previous curve is performed before 0.05s. Figure 3 The torque based on the new data control refers to the torque pulsation suppression method based on digital domain control adopted in this application, and the latter curve is performed after 0.05s.

[0144] Depend on Figure 3 By comparing the two curves before and after, it can be seen that the torque pulsation suppression method based on digital domain control of the present application can significantly reduce the torque pulsation of the electromechanical drive motor.

[0145] like Figure 4 and Figure 5As shown in the figure, after the cost function is constructed, the torque pulsation and phase current of the electromechanical drive motor need to be optimized for a single objective. By adjusting the turn-on angle and modifying the turn-off angle accordingly, the commutation conduction area is made symmetrical, and the torque pulsation and phase current of the electromechanical drive motor are recorded. Here, the third-order Fourier series fitting curve is used, and the particle swarm optimization (PSO) algorithm is used to perform single-objective optimization on the torque pulsation and phase current, respectively.

[0146] Furthermore, the expression of torque ripple is:

[0147]

[0148] in, represents the torque ripple obtained by single-objective optimization, represents the maximum value of all torque ripples of the electromechanical drive motor, represents the minimum value of all torque ripples of the electromechanical drive motor, Represents the average value of all torque ripples of the electromechanical drive motor.

[0149] Depend on Figure 4 It can be seen that when the number of iterations is 15, the phase current is the minimum, which is 8.8508A, and then the effective value of the phase current no longer changes. At this time, the minimum phase current represents the minimum value of the fitting function of the phase current according to the opening angle change.

[0150] Depend on Figure 5 It can be seen that when the number of iterations is 6, the torque pulsation is the smallest, which is 0.3968. After that, as the number of iterations increases, the torque pulsation no longer decreases.

[0151] Furthermore, if Figure 6 As shown in the figure, on the basis of single-objective optimization, a multi-objective optimization function is set, which is about the opening angle The multi-peak function of is 2.7311°, that is Figure 6 When the black dot in the figure is located, the multi-objective optimization function achieves the minimum value, which further improves the control performance of the electromechanical drive motor, thereby reducing the copper loss while reducing the torque pulsation. Here, it is necessary to adjust the turn-on angle until the multi-objective optimization function reaches the minimum, and change the turn-off angle synchronously to make the commutation conduction area symmetrical.

[0152] The expression of the multi-objective optimization function is:

[0153]

[0154] And meet: .

[0155] in, represents the multi-objective optimization function, represents the weight coefficient of the phase current of the electromechanical drive motor, represents the weight coefficient of torque ripple in the multi-objective optimization function, represents the phase current obtained by single objective optimization, The minimum value of phase current obtained by single objective optimization, represents the torque ripple obtained by single-objective optimization, represents the minimum value of torque ripple obtained by single-objective optimization, express The index of .

[0156] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0157] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0158] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed in the present application, and these modifications or substitutions should be included in the protection scope of the present application.

[0159] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary technical means in the art that are not disclosed in the present application.

Claims

1. A method for suppressing torque pulsation of an electromechanical drive motor based on digital domain control, characterized in that: The following steps are involved: A current-flux-rotor position lookup table and a current-torque-rotor position lookup table of the electromechanical drive motor are constructed based on a feedforward neural network, wherein the current-flux-rotor position lookup table includes the rotor position at all times and the phase flux value corresponding to the phase current value, and the current-torque-rotor position lookup table includes the rotor position at all times and the torque value corresponding to the phase current value; Calculating the excitation phase torque and the demagnetization phase torque in sequence by using the current-flux-rotor position lookup table and the current-torque-rotor position lookup table, and constructing a torque allocation function by using the excitation phase torque and the demagnetization phase torque; Discretizing the voltage balance equation, respectively predicting the phase flux linkage values ​​and the rotor positions at all moments from the next moment, and calculating the phase current prediction values ​​at the corresponding moment according to the predicted phase flux linkage prediction values ​​and the rotor prediction positions at all moments; The difference between the predicted value of the phase current and the actual value of the phase current at each moment is calculated respectively to obtain the phase current error value at the corresponding moment, the phase current error values ​​at the previous moments are input into the feedforward neural network respectively, and the phase current compensation values ​​at the corresponding moments are obtained respectively using the output results of the feedforward neural network; Using the phase current prediction value and the phase current compensation value at each moment, respectively obtain the torque value at the corresponding moment in the current-torque-rotor position lookup table; The torque values ​​at all moments are used to construct cost functions at corresponding moments respectively, and the switching states when the cost function at each moment is closest to the torque distribution function are found respectively, and the switching states at all moments are used to control the electromechanical drive motor, thereby suppressing torque pulsation.

2. The method for suppressing torque pulsation of an electromechanical drive motor based on digital domain control according to claim 1, characterized in that: The feedforward neural network is a back propagation neural network.

3. The method for suppressing torque pulsation of an electromechanical drive motor based on digital domain control according to claim 1, characterized in that: The steps of using the current-flux-rotor position lookup table and the current-torque-rotor position lookup table to sequentially calculate the excitation phase torque and the demagnetization phase torque, and using the excitation phase torque and the demagnetization phase torque to construct a torque allocation function include: Calculating a commutation overlap angle according to relevant parameters of the electromechanical drive motor; Using the torque value and the rotor position at the current moment, sequentially searching for the corresponding phase flux value in the current-torque-rotor position lookup table and the current-flux-rotor position lookup table; Calculating the excitation phase flux using the phase flux value and the rotor position at the current moment, and sequentially searching for the corresponding excitation phase torque using the current-flux-rotor position lookup table and the current-torque-rotor position lookup table; Calculating the demagnetization phase torque using the excitation phase torque; The torque distribution function is constructed using the excitation phase torque and the demagnetization phase torque.

4. The method for suppressing torque pulsation of an electromechanical drive motor based on digital domain control according to claim 3 is characterized in that: The expression of the commutation overlap angle is: (1) in, It indicates the angle of the overlapping part of the two phases when the two adjacent phases of the electromechanical drive motor are switching the phase current, that is, the commutation overlap angle. represents the rotor pole pitch of the electromechanical drive motor, represents the stator pole arc of the electromechanical drive motor, Represents the rotor pole arc of an electromechanical drive motor; The expression of the excitation phase flux is: (2) in, represents the excitation phase flux, It represents the slope of the excitation phase flux, , represents the reference phase flux, represents the opening angle, Indicates the rotor position at the current moment.

5. The method for suppressing torque pulsation of an electromechanical drive motor based on digital domain control according to claim 4 is characterized in that: The expression of the excitation phase torque is: (3) in, represents the excitation phase torque, Indicates about The function of ; The expression of the demagnetization phase torque is: (4) in, represents the demagnetization phase torque, Indicates the load torque of the electromechanical drive motor; The expression of the torque distribution function is: (5) in, Indicates the rotor position The corresponding torque distribution function is: represents the cut-off angle, represents the rotor period angle.

6. The method for suppressing torque pulsation of an electromechanical drive motor based on digital domain control according to claim 1, characterized in that: The expression of the phase flux prediction value is: (6) in, Indicates The predicted value of phase flux at time Indicates The phase flux value at the moment, represents the sampling step length, Indicates The phase voltage value at the moment, Indicates the resistance value of the phase resistor, Indicates Phase current value at the moment; The expression of the predicted rotor position is: (7) in, Indicates The predicted rotor position at time , Indicates The rotor position at time, Indicates The speed of the electromechanical drive motor at that moment.

7. The method for suppressing torque pulsation of an electromechanical drive motor based on digital domain control according to claim 6, characterized in that: The expression of the phase current prediction value is: (8) in, Indicates The predicted phase current value at time Represents the corresponding phase current value in the current-flux-rotor position lookup table.

8. The method for suppressing torque pulsation of an electromechanical drive motor based on digital domain control according to claim 1, characterized in that: The steps of respectively calculating the difference between the phase current prediction value and the phase current actual value at each moment to obtain the phase current error value at the corresponding moment, respectively inputting the phase current error values ​​at the previous moments into the feedforward neural network, and respectively obtaining the phase current compensation values ​​at the corresponding moments using the output results of the feedforward neural network include: The phase current error values ​​at the previous several moments are respectively input into the feedforward neural network, and by adjusting the weights of the nodes between the multiple neurons, the output result of the feedforward neural network is made close to the actual phase current error value of the electromechanical drive motor, and the phase current compensation value at the corresponding moment is calculated by using the actual phase current error value at each moment; The expression of the phase current compensation value is: (9) in, Indicates Phase current compensation value at time Indicates The actual error value of the phase current at the moment, Indicates The predicted phase current at time.

9. The method for suppressing torque pulsation of an electromechanical drive motor based on digital domain control according to claim 8, characterized in that: The expression of the torque value is: (10) in, Indicates The torque value at the moment, Represents the corresponding torque value in the current-torque-rotor position lookup table, Indicates The predicted rotor position at time.

10. The method for suppressing torque ripple of an electromechanical drive motor based on digital domain control according to claim 1, characterized in that: The steps of constructing cost functions at corresponding moments respectively using the torque values ​​at all moments, finding the switch state when the cost function at each moment is closest to the torque distribution function, and controlling the electromechanical drive motor using the switch state at all moments to suppress torque pulsation include: Constructing the cost functions at all moments respectively, and finding the switch state when the cost function at each moment is closest to the torque distribution function respectively; Controlling the electromechanical drive motor using the switch state at all times, and calculating the minimum torque pulsation in the control process at each moment, so as to suppress the torque pulsation; The expression of the cost function is: (11) in, represents the cost function, represents the weight coefficient of torque ripple in the cost function, represents the weight coefficient of copper loss, Indicates the electromechanical drive motor Mutually, represents the number of phases of the electromechanical drive motor, represents the torque distribution function, Indicates The torque value at the moment, Indicates Phase current compensation value at the moment.

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