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CN-122001269-A - SRM harmonic closed-loop torque ripple suppression method based on current square

CN122001269ACN 122001269 ACN122001269 ACN 122001269ACN-122001269-A

Abstract

The invention discloses a current square-based SRM harmonic closed-loop torque ripple suppression method which comprises the steps of (1) constructing an expression of electromagnetic torque containing current square and solving a current square harmonic model with optimal torque ripple, (2) obtaining an optimal current square bias value of the current square and an optimal current square model with optimal torque ripple, (3) generating a fundamental wave amplitude reference value of the current square model with optimal torque ripple, obtaining an actual current square excitation model of an actual injection motor and an actual current square model of an output motor, (4) performing a correction process for an auxiliary channel to realize closed-loop suppression of the torque ripple, and (5) compensating transient torque peaks in a specific electric angle range to complete harmonic closed-loop torque ripple suppression and realize a torque ripple optimal scheme. The invention realizes systematic suppression of the torque pulsation of the switched reluctance motor by constructing a double-layer compensation framework based on current square harmonic injection and torque real-time feedback.

Inventors

  • SUN QINGGUO
  • CAO YUXIN
  • YUAN YE

Assignees

  • 河北工业大学

Dates

Publication Date
20260508
Application Date
20260213

Claims (10)

  1. 1. A method for restraining SRM harmonic closed-loop torque pulsation based on current square, which is characterized by comprising the following steps: Step 1, introducing current square as an intermediate control variable, deducing an expression of electromagnetic torque T e 'containing current square according to a simplified three-phase inductance model, and then reversely solving the expression of electromagnetic torque T e ' containing current square to obtain a current square harmonic model with optimal torque pulsation; Step2, according to the current square harmonic model with optimal torque ripple obtained in the step1, solving non-negative constraint of the current square harmonic model to obtain a current square optimal direct current bias value; Step 3, acquiring the position electric angle of a rotor of the switch reluctance motor in real time through a position sensor, calculating the actual rotating speed of the motor, calculating the rotating speed error between the actual rotating speed and the set rotating speed, then processing the rotating speed error through a rotating speed ring to generate a fundamental wave amplitude reference value of a current square model with optimal torque pulsation in the step 2, substituting the fundamental wave amplitude reference value into the current square model with optimal torque pulsation in the step 2 to obtain a current square excitation model actually injected into the motor, setting the current square excitation model as a control current square model of a main channel, and generating a corresponding main channel control signal through a hysteresis current controller to control the switch reluctance motor to obtain an actual current square model of the output motor; Step 4, in order to realize closed-loop suppression of torque pulsation, an auxiliary channel performs the following processes of collecting and extracting harmonic amplitude values in an actual current square model of the output motor in step 3 in real time, comparing the harmonic amplitude values in the actual current square model of the output motor with the harmonic amplitude values in an actual injection motor in step 3 to calculate harmonic compensation quantity, injecting the harmonic compensation quantity into the current square excitation model in the actual injection motor in step 3 to realize correction of the harmonic amplitude values in the actual current square model of the output motor in step 3, setting a convergence threshold value for the harmonic compensation quantity, and judging that the correction is completed and stopping updating when the harmonic compensation quantity is lower than the convergence threshold value; And 5, compensating dynamic disturbance which is not covered by the closed loop correction in the step 4, namely, an instantaneous torque peak which appears in a specific electric angle range, and completing harmonic closed loop torque ripple suppression to realize a torque ripple optimal scheme.
  2. 2. The SRM harmonic closed-loop torque ripple suppression method based on current square as claimed in claim 1, wherein in step 1, the specific step of deriving the expression of the electromagnetic torque T e ' containing the current square is: S11, defining an initial sinusoidal excitation current waveform, modeling the inductance of the switched reluctance motor to obtain a three-phase inductance model, and then obtaining an expression of electromagnetic torque T e of the traditional switched reluctance motor according to the initial sinusoidal excitation current waveform and the three-phase inductance model; s12, simplifying the three-phase inductance model in the step S11 to obtain a simplified three-phase inductance model; S13, introducing current square as an intermediate control variable, and taking the current square and the simplified three-phase inductance model in the step S12 into an expression between the electromagnetic torque T e of the traditional switched reluctance motor and the initial sinusoidal excitation current to obtain an expression of the electromagnetic torque T e ' containing the current square.
  3. 3. The SRM harmonic closed-loop torque ripple suppression method based on current square as claimed in claim 2, wherein in step S11, an initial sinusoidal excitation current waveform is defined as follows: (1) In the formula (1), i a 、i b 、i c respectively represents an initial sinusoidal excitation current waveform of the switched reluctance motor, i 0 represents a direct current component in the initial sinusoidal excitation current waveform of the switched reluctance motor, i m represents an m-order harmonic component in the initial sinusoidal excitation current waveform of the switched reluctance motor, θ e is a rotor position electrical angle, and the invention assumes that a rotor position corresponding to the superposition of a-phase stator salient poles and rotor salient pole central axes is an initial position 0 degree of the rotor position electrical angle; In step S11, the three-phase inductance model is represented by a sine function: (2) In the formula (2), L a 、L b 、L c represents three-phase inductance in a three-phase inductance model of the switched reluctance motor, L 0 represents direct current component in the three-phase inductance model, and L n represents n-order inductance harmonic component in the three-phase inductance model; In step S11, the expression for obtaining the electromagnetic torque T e of the traditional switched reluctance motor is specifically that for the three-phase switched reluctance motor, under the static abc coordinate system, the expression between the electromagnetic torque T e of the traditional switched reluctance motor and the initial sinusoidal excitation current is as follows: (3) In the formula (3), T e is electromagnetic torque of a traditional switch reluctance motor, and N r is the number of poles of a rotor; Then, the initial sinusoidal excitation current waveform and the three-phase inductance model are brought into formula (3), and an expression of electromagnetic torque T e of the traditional switched reluctance motor is obtained: (4) in the formula (4), i m 、i m1 、i m2 is the m-th and m 1 、m 2 -th harmonic components in the three-phase initial excitation current waveform.
  4. 4. The SRM harmonic closed-loop torque ripple suppression method based on current square as claimed in claim 2, wherein step S12 is specifically to preserve only the significant inductive harmonic components, i.e. the fundamental, secondary and fourth inductive harmonic components in the three-phase inductive model, according to the set amplitude threshold, and consider the remaining inductive harmonic components as modeling disturbances in a unified way, to obtain a simplified three-phase inductive model: (5) in the formula (5), L 1 、L 2 、L 4 represents a fundamental inductance harmonic component, a secondary inductance harmonic component, and a fourth inductance harmonic component in a three-phase inductance model of the switched reluctance motor, respectively.
  5. 5. The SRM harmonic closed-loop torque ripple suppression method based on current square as claimed in claim 2, wherein in step S13, the current square model is: (6) In the formula (5), i a ' represents an a-phase current square model, i 0 ' represents a direct current component in the a-phase current square model, and i m ' represents a harmonic component of the m-th a-phase current square model; In step S13, the electromagnetic torque T e ' including the current square is expressed as: (7) in the formula (7), T e 'is an electromagnetic torque including a current square, and i 1 '、i 2 '、i 4 '、i 3m+1 '、i 3m+2 ' represents a fundamental current square harmonic component, a second current square harmonic component, a fourth current square harmonic component, and 3m+1, 3m+2 current square harmonic components.
  6. 6. The SRM harmonic closed-loop torque ripple suppression method based on current square according to claim 5, wherein in step 1, an expression of the electromagnetic torque T e ' including the current square is solved in an inverse manner to obtain a current square harmonic model with optimal torque ripple, specifically: The general expression of the A11 current square harmonic model is as follows: (8) to avoid the instability of the system caused by the coupling of the higher-order current square harmonic component in the formula (8) and the inductance harmonic component in the simplified three-phase inductance model, only the first two-order current square harmonic component in the formula (8) is reserved, and the simplified expression of the electromagnetic torque T e ' containing the current square is as follows: (9) A12, let the reluctance torque in the simplified expression containing the electromagnetic torque T e '' with current square obtained in the step A11 be 0, so as to determine the calculation formula of the second harmonic amplitude in the current square harmonic model with optimal torque pulsation as follows: (10) A13, introducing the calculation result of the formula (10) into the formula (6), and solving a current square harmonic model with optimal torque ripple, wherein the current square harmonic model is obtained as follows: (11)。
  7. 7. The SRM harmonic closed-loop torque ripple suppression method based on current square as claimed in claim 1, wherein in step 2, the solving process of the current square optimal dc offset value is as follows: because the sinusoidal exciting current is three-phase symmetrical, the current square direct current offset of the A phase is calculated only and can be applied to the other two phases as the universal current square direct current offset, and the current square model with optimal torque pulsation is assumed as follows: (12) and then converting the non-negative constraint problem of the current square model with optimal torque pulsation into a solution function extremum problem, wherein the solution function extremum problem is as follows: (13) and then carrying out variable replacement on the formula (13), enabling cos theta e =u, converting the trigonometric function solving problem into a unitary quadratic equation, and further solving the corresponding current square optimal direct current offset value: (14); In step 2, the result of the equation (14) is taken into the equation (12), and a current square model with optimal torque ripple is obtained as follows: (15)。
  8. 8. The SRM harmonic closed-loop torque ripple suppression method based on current square as claimed in claim 1, wherein in step 4, the calculation of the harmonic compensation quantity is specifically implemented by collecting data of one complete period of an actual current square model of the output motor in step 3 in real time, extracting each subharmonic component amplitude in the actual current square model of the output motor in step 3 through harmonic analysis, comparing each obtained subharmonic component amplitude with the harmonic amplitude in an actual current square excitation model of the input motor in step 3 to obtain each difference value of each subharmonic component, and determining the corresponding difference value as the harmonic compensation quantity of the subharmonic component to obtain the harmonic compensation quantity of each subharmonic component; In the step 4, the correction process is as follows, when the next period of the current square excitation model in the actual injection motor in the step 3 starts, the harmonic compensation quantity of each subharmonic component is injected into the current square excitation model in the actual injection motor in the step 3, the process iterates in a unit cycle of one period of the current square excitation model in the actual injection motor in the step 3, the actual current square model of the output motor in the step 3 is enabled to continuously approach the current square excitation model in the actual injection motor in the step 3, meanwhile, a harmonic compensation quantity convergence criterion is introduced for improving the efficiency of closed loop suppression of torque pulsation, when the harmonic compensation quantity is lower than a convergence threshold value, the fact that the harmonic compensation quantity of the subharmonic component is corrected is judged, otherwise, the harmonic compensation quantity is calculated continuously and injected into the current square excitation model in the actual injection motor in the step 3 until the convergence condition is met.
  9. 9. The SRM harmonic closed-loop torque ripple suppression method based on current square as claimed in claim 1, wherein the step 5 specifically comprises the steps of: S51, acquiring actual output torque T real of each phase of a torque sensor in the running process of the switched reluctance motor, and determining a specific electric angle range in which an instantaneous torque peak appears; S52, according to the expression of the electromagnetic torque T e ' containing the current square in the step 1, an expression of the average torque T ave is obtained, and then the instantaneous torque peak appearing in a specific electric angle range is compared with the average torque T ave to obtain the real-time torque compensation quantity in the specific electric angle range of the actual output torque T real of each phase; and S53, carrying out inverse solution on the torque real-time compensation quantity in the step S52 to obtain a current square compensation quantity, and compensating the current square compensation quantity to respective corresponding phases of the current square excitation model in the actual injection motor in the step 3 to realize real-time compensation of the torque in a specific electric angle range.
  10. 10. The SRM harmonic closed-loop torque ripple suppression method based on current square as claimed in claim 9, wherein in step S52, the expression of the average torque T ave is: (16) to ensure the effectiveness of injection torque compensation, only the fundamental component in the current square harmonic model of the torque ripple optimization of step 1 and the simplified three-phase inductance model of step 1 employed in equation (16) is reserved; In step S53, the current square compensation amount is obtained by solving the equation (17) in reverse: (17) In the formula (17), T ave represents an average torque, T real represents an actual output torque of the switched reluctance motor, and i' represents a current square compensation amount of an instantaneous torque spike.

Description

SRM harmonic closed-loop torque ripple suppression method based on current square Technical Field The invention belongs to the technical field of motor control, and particularly relates to a SRM harmonic closed-loop torque ripple suppression method based on current square. Background The switched reluctance motor (Switched Reluctance Motor, SRM) has potential in the fields of electric automobiles, aerospace, industrial driving and the like because of the simple structure of the rotor, firmness and durability, lower cost and strong adaptability. However, the inherent doubly salient structure and conventional square wave current control strategy can result in a large number of harmonics in the phase currents, which in turn can cause significant torque ripple, vibration and noise. This problem has become a key bottleneck for further popularization and application of SRM in occasions with high requirements on running stability. In order to reduce torque pulsation of the switched reluctance motor and improve system operation stability, current researches are mainly developed around two aspects of motor body structural optimization and advanced control strategies. In the aspect of motor body structure optimization, researchers generally improve magnetic circuit characteristics by adjusting the pole numbers of stator and rotor, optimizing pole shoes and tooth arc structures, adopting a diagonal pole design and the like, so that vibration and noise are restrained to a certain degree. However, such structural optimization is often accompanied by increased design and manufacturing costs, and its optimization effect is also often limited to specific operating conditions, is difficult to adapt over a wide operating range, and is not capable of completely eliminating current harmonics introduced by the control system and torque ripple during commutation. In terms of control strategies, the primary methods currently include direct torque control and indirect torque control. The direct torque control has the advantages of simple structure and quick response, but has the problems of larger torque pulsation, unstable switching frequency and the like. The indirect torque control realizes the indirect regulation and control of the torque by improving the control performance of a current closed loop or a flux linkage closed loop. In particular, the indirect instantaneous torque control is generally implemented by using a torque distribution function to generate a phase torque command, so that the torque output in the phase change process is stabilized, and the optimized control effect is realized by selecting the corresponding distribution function according to different application scenes. Part of researches are used for referencing the control concept of an alternating current motor, but the traditional torque distribution function is generally defined only based on an ideal electromagnetic torque generation interval, so that the time delay of the rising and falling processes of phase current in an actual system is not fully considered, the torque pulsation suppression effect is limited, and the motor output torque still has instability. In addition to the above method, a harmonic current injection method is also used to suppress torque ripple of the switched reluctance motor. According to the method, based on a mathematical model of motor torque, a theoretical optimal current waveform capable of reducing torque pulsation is obtained by reversely solving a torque equation, and then corresponding multiple harmonic components are injected into basic reference current, so that targeted inhibition is realized. However, most harmonic current injection methods only can ensure that the initial excitation waveform is consistent with a theoretical target, and do not fully consider whether the current waveform actually applied to the motor can maintain the expected form under the actions of a nonlinear motor structure and a power converter. In other words, the conventional current injection strategy is mostly implemented based on an open loop framework, but has a simple structure, but is difficult to ensure the effectiveness of the injection current in actual operation, and has limited effect of suppressing torque ripple. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a SRM harmonic closed-loop torque ripple suppression method based on current square. The technical scheme for solving the technical problems is that the invention provides a SRM harmonic closed-loop torque ripple suppression method based on current square, which is characterized by comprising the following steps: Step 1, introducing current square as an intermediate control variable, deducing an expression of electromagnetic torque T e 'containing current square according to a simplified three-phase inductance model, and then reversely solving the expression of electromagnetic torque T e' containing current square to obtain a curre