阅读说明：本技术 一种变磁通永磁电机带速重投控制方法及系统 (Variable flux permanent magnet motor belt speed re-throwing control method and system ) 是由 陈俊桦 曲荣海 于 2020-03-24 设计创作，主要内容包括：本发明公开了一种变磁通永磁电机带速重投控制方法及系统,属于变磁通永磁电机驱动控制领域。包括：变磁通永磁电机在旋转状态下的重投时刻注入q轴脉冲电压；脉冲电压加载结束时,根据变磁通永磁电机的dq轴感应电流和电磁同步转速,估计变磁通永磁电机的d轴增量电感；根据电机饱和效应导致的增量电感与变磁通永磁电机永磁磁链的关系曲线,以估计的d轴增量电感反演变磁通永磁电机的永磁磁链；基于反演的变磁通永磁电机的永磁磁链,进行重投过程中的反电势补偿。本发明提供的q轴脉冲电压注入方法,该方法注入当前转速下的最大反电势电压,避免负d轴电流产生,保护永磁体不被退磁。(The invention discloses a method and a system for controlling the belt speed re-throw of a variable flux permanent magnet motor, and belongs to the field of drive control of the variable flux permanent magnet motor. The method comprises the following steps: injecting q-axis pulse voltage into the variable flux permanent magnet motor at the time of re-throwing in the rotating state; when the pulse voltage loading is finished, estimating a d-axis incremental inductance of the variable flux permanent magnet motor according to the dq-axis induction current and the electromagnetic synchronous rotating speed of the variable flux permanent magnet motor; according to a relation curve of incremental inductance and variable flux permanent magnet flux linkage of the variable flux permanent magnet motor caused by motor saturation effect, inverting the permanent magnet flux linkage of the variable flux permanent magnet motor by the estimated d-axis incremental inductance; and performing back electromotive force compensation in the re-casting process based on the inverted permanent magnetic flux linkage of the variable flux permanent magnet motor. According to the q-axis pulse voltage injection method provided by the invention, the maximum back electromotive voltage at the current rotating speed is injected, so that the generation of negative d-axis current is avoided, and the permanent magnet is protected from demagnetization.)

1. A variable flux permanent magnet motor strip speed re-throw control method is characterized in that a low coercive force permanent magnet is adopted by the variable flux permanent magnet motor, and residual magnetism of the low coercive force permanent magnet is changed through armature current, and the method comprises the following steps:

s1, injecting q-axis pulse voltage into a variable flux permanent magnet motor at a re-throwing moment in a rotating state;

s2, when the pulse voltage loading is finished, estimating a d-axis incremental inductance of the variable flux permanent magnet motor according to the dq-axis induction current and the electromagnetic synchronous rotating speed of the variable flux permanent magnet motor;

s3, inverting the permanent magnet flux linkage of the variable flux permanent magnet motor by the estimated d-axis incremental inductance according to a relation curve of the incremental inductance and the permanent magnet flux linkage of the variable flux permanent magnet motor caused by the motor saturation effect;

and S4, carrying out back electromotive force compensation in the re-casting process based on the inverted permanent magnetic flux linkage of the variable flux permanent magnet motor.

2. The method of claim 1, wherein the q-axis pulse voltage is a maximum back-emf voltage at a current electromagnetic synchronous speed.

3. The method of claim 2, wherein the maximum back-emf voltage is a product of a maximum permanent magnet flux linkage of the variable flux permanent magnet motor and a current electromagnetic speed of the motor.

4. A method according to any one of claims 1 to 3, wherein the width of the pulses is from one PWM period to ten PWM periods.

5. The method of any one of claims 1 to 4, wherein the d-axis incremental inductance of the variable flux permanent magnet motor is estimated according to the dq-axis induced current and the electromagnetic synchronous speed of the variable flux permanent magnet motor by the following formula:

wherein, L d_iRepresenting d-axis incremental inductance, w₁Indicating electromagnetically synchronous rotational speed, L_qRepresenting the q-axis apparent inductance, I_qRepresenting the q-axis induced current, R, of a variable flux permanent magnet machine_aRepresenting armature resistance, I_dRepresenting the d-axis induced current of a variable flux permanent magnet motor.

6. The method according to any one of claims 1 to 5, wherein back electromotive force compensation in the re-projection process is performed based on the permanent magnetic flux linkage of the inverted variable flux permanent magnet motor, and the specific formula is as follows:

E＝w₁*Φ_est

wherein, w₁Indicating electromagnetically synchronous speed, phi_estRepresenting the permanent magnet flux linkage of a variable flux permanent magnet motor.

7. A speed-changing re-throwing control system of a variable flux permanent magnet motor, which is characterized by adopting the speed-changing re-throwing control method of the variable flux permanent magnet motor according to any one of claims 1 to 6.

Technical Field

The invention belongs to the field of variable flux permanent magnet motor drive control, and particularly relates to a variable flux permanent magnet motor strip speed re-throw control method and system.

Background

The variable flux permanent magnet motor is a special permanent magnet motor and is characterized in that the permanent magnet adopted by the motor is a low-coercivity permanent magnet, and the control of the magnetic field of a motor rotor can be realized through online magnetizing and demagnetizing control. The variable flux permanent magnet motor has the advantages that when the motor runs in a high-speed interval, the back electromotive force of the motor is lower than the limit of bus voltage through demagnetization operation, so that continuous weak magnetic current is eliminated, and the efficiency of the motor in the high-speed interval is improved.

Similarly, the variable flux permanent magnet motor also has the problem of controlling the tape speed re-throw. The particularity of the variable flux permanent magnet motor with fast re-throw is that compared with the traditional permanent magnet motor, the rotor magnetic field of the variable flux permanent magnet motor is not fixed, and the impact current can not be restrained by adopting a compensation method of the counter potential of the fixed magnetic linkage in the traditional method. Because the stator current is zero during the free rotation of the variable flux permanent magnet motor, the stator current cannot be observed in an observer mode.

The control of the speed of the permanent magnet motor with variable magnetic flux also requires attention, and the possible impact current generated at the moment of the re-throw risks the demagnetization of the motor. Although a variable flux permanent magnet motor can perform the recovery of the magnetic field by re-magnetization, the motor control accuracy during the demagnetization state will be severely affected. At present, no relevant research focuses on the problem of the tape speed re-throwing of the variable flux permanent magnet motor.

Disclosure of Invention

Aiming at the defects and the improvement requirements of the prior art, the invention provides a strip speed re-throwing control method and a strip speed re-throwing control system for a variable flux permanent magnet motor, and aims to provide the strip speed re-throwing control system for the variable flux permanent magnet motor, which is used for inhibiting impact current in the strip speed re-throwing process of the variable flux permanent magnet motor and preventing demagnetization of the variable flux permanent magnet motor in the re-throwing process.

To achieve the above object, according to a first aspect of the present invention, there is provided a method for controlling a variable flux permanent magnet motor with a fast re-throw, the variable flux permanent magnet motor using a low coercive force permanent magnet, the remanence of the low coercive force permanent magnet being changed by an armature current, the method comprising the steps of:

s1, injecting q-axis pulse voltage into a variable flux permanent magnet motor at a re-throwing moment in a rotating state;

s2, when the pulse voltage loading is finished, estimating a d-axis incremental inductance of the variable flux permanent magnet motor according to the dq-axis induction current and the electromagnetic synchronous rotating speed of the variable flux permanent magnet motor;

s3, inverting the permanent magnet flux linkage of the variable flux permanent magnet motor by the estimated d-axis incremental inductance according to a relation curve of the incremental inductance and the permanent magnet flux linkage of the variable flux permanent magnet motor caused by the motor saturation effect;

and S4, carrying out back electromotive force compensation in the re-casting process based on the inverted permanent magnetic flux linkage of the variable flux permanent magnet motor.

Preferably, the q-axis pulse voltage is a maximum back electromotive voltage at the current electromagnetic synchronous rotation speed.

Preferably, the maximum back electromotive voltage is the product of the maximum permanent magnet flux linkage of the variable flux permanent magnet motor and the current electromagnetic rotating speed of the motor.

Preferably, the width of the pulse is one PWM period to ten PWM periods.

Preferably, the d-axis incremental inductance of the variable flux permanent magnet motor is estimated according to the dq-axis induced current and the electromagnetic synchronous rotating speed of the variable flux permanent magnet motor, and the specific formula is as follows:

wherein, L d_iRepresenting d-axis incremental inductance, w₁Indicating electromagnetically synchronous rotational speed, L_qRepresenting the q-axis apparent inductance, I_qRepresenting the q-axis induced current, R, of a variable flux permanent magnet machine_aRepresenting armature resistance, I_dRepresenting the d-axis induced current of a variable flux permanent magnet motor.

Preferably, the back electromotive force compensation in the re-projection process is performed based on the permanent magnetic flux linkage of the inverted variable flux permanent magnet motor, and the specific formula is as follows:

E＝w₁*Φ_est

wherein, w₁Indicating electromagnetically synchronous speed, phi_estRepresenting the permanent magnet flux linkage of a variable flux permanent magnet motor.

To achieve the above object, according to a second aspect of the present invention, a variable flux permanent magnet motor speed re-throw control system is provided, which employs the variable flux permanent magnet motor speed re-throw control method according to the first aspect.

Generally, by the above technical solution conceived by the present invention, the following beneficial effects can be obtained:

the invention injects pulse voltage at the time of re-throwing under the free rotation state of the variable magnetic flux permanent magnet motor, and estimates the incremental inductance of the motor according to the induced current and the rotating speed of the motor. Based on different characteristics of the increment inductance in different variable flux permanent magnet motor magnetizing states, the increment inductance is used as an estimation method of the variable flux permanent magnet motor magnetizing state. And based on the estimated magnetizing state of the variable-flux permanent magnet motor, carrying out counter potential compensation in the re-throwing process and eliminating the current impact of re-throwing. The pulse voltage injected by the invention is q-axis pulse voltage, so that the generation of negative d-axis current is avoided, and the permanent magnet is protected from demagnetization.

Drawings

FIG. 1 is a schematic diagram of a belt speed re-throwing control system of a variable flux permanent magnet motor provided by the present invention;

FIG. 2 is a schematic block diagram of the system algorithm implementation provided by the present invention;

FIG. 3 is a schematic diagram of signal levels for a tape speed re-launch control process provided by the present invention;

FIG. 4 is a schematic block diagram of a tape speed re-projection section algorithm provided by the present invention;

FIG. 5 is a graph of the relationship between the magnetizing state and the d-axis incremental inductance provided by the present invention;

fig. 6 is a schematic block diagram of the motor vector control provided by the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

As shown in fig. 1, a variable flux permanent magnet motor 109 is powered by a three-phase half-bridge power electronic inverter 105 powered by a dc power source 106. Variable flux permanent magnet motorThe rotor shaft is provided with a position detector 110 for detecting and calculating the electromagnetic angle theta of the rotor, and the synchronous rotating speed w of the motor is calculated by a speed calculating part 111₁. A current sensor 108 is installed on a three-phase outlet line of the three-phase half-bridge inverter circuit 105, and motor phase currents Iu and Iv are detected and processed through a coordinate transformation 107 to obtain motor dq axis current feedback values Id and Iq.

The algorithm executing part 101 is an algorithm executing part for normal operation and tape speed re-projection of the motor. The algorithm execution part collects feedback currents Id and Iq and a motor synchronous rotating speed w1, obtains motor dq axis voltage commands Ud and Uq through algorithm operation calculation, and generates a PWM enabling signal OPpwm. The voltage commands Ud and Uq are transmitted to the coordinate transformation unit 102, the motor phase voltage commands Uu, Uv and Uw are obtained through left transformation, and the switching signals of each bridge arm in the three-phase half-bridge inverter circuit 105 are obtained through the modulation algorithm of the PWM control unit 103. The PWM control unit 103 outputs an arm signal, and the PWM enable unit 104 processes the arm signal, and controls on/off of the OPpwm signal generated by the algorithm execution unit 101.

As shown in fig. 2, the operation commander 201 generates an instruction signal OPs for system operation. The determiner 202 switches the algorithm operation based on the input OPs signal, and determines whether the algorithm executing unit 101 operates the vector control unit 203, the tape speed re-projection unit 204, or the non-algorithm operation state.

As shown in fig. 3, OPs have three levels, N is a normal operation level, 0 is a latch level, and R is a re-throw level. In the interval from 0 to t0, OPs is N level, the algorithm execution part runs the vector control part 203 program, the algorithm execution part outputs Ud and Uq commands generated by the vector control part 203 and outputs PWM enable signal OPpwm high level, and PWM enables the motor to be supplied with power. When the operation commander 201 judges that the motor is lack of power supply from the power supply 106 or the algorithm is abnormal, the operation commander outputs OPs to a locking level 0 at the time of t0, the OPpwm signal output is zero, the PWM is locked for power supply, and Ud and Uq have no output. The operation commander 201 determines at time t1 that the motor state is considered to be able to be restarted, outputs the OPs signal restart level R, and operates the tape speed restart unit 204, and at this time, the voltage command and the OPpwm signal are generated by the tape speed restart unit 204. At time t2, the tape speed re-projection control is completed, and the set signal pulse OPrst is generated by the tape speed re-projection unit 204. The operation commander 201 receives the set pulse OPrst, and recovers the normal operation level N, that is, the entire control flow from power-off to tape speed re-projection is completed.

As shown in fig. 4, the tape speed playback unit 204 receives the OPs signal at the R level, and then performs subsequent tape speed playback control. The tape speed re-casting method comprises the steps of injecting a pulse voltage signal into a motor, and calculating d-axis incremental inductance according to feedback dq-axis current; because the d-axis incremental inductance is related to the magnetizing degree of the variable flux permanent magnet motor, the magnetizing state of the variable flux permanent magnet motor can be estimated through the incremental inductance, and the estimated magnetizing state Φ est is output to the vector control unit 203 for use.

In order to prevent the demagnetization of the variable magnetic flux permanent magnet motor in the speed re-throw process, the invention provides a q-axis pulse voltage injection method, which injects the maximum back electromotive voltage at the current rotating speed, avoids the generation of negative d-axis current and protects the permanent magnet from demagnetization.

The following description is given with reference to equations (1) and (2) of the dq-axis voltage of the flux-changing permanent magnet motor.

Ud＝Ra*Id+Ldi*dId/dt-w1*Lq*Iq…(1)

Uq＝Ra*Iq+Lqi*dIq/dt+w1*Ld*Id+w1*Φf…(2)

Wherein Ra is armature resistance, L di and L qi are dq axis incremental inductance, phi f is the magnetizing state of the current variable flux permanent magnet motor, and the variable is unknown quantity in the initial stage of tape speed re-casting.

In order to prevent the generation of negative d-axis current caused by the injection of a pulse voltage signal in the above-described tape speed re-throw control. The speed-changing re-projection part 204 injects a voltage Uq to the q axis, the value of the voltage Uq is the product of the maximum magnetizing state Φ fm of the flux-changing permanent magnet motor and the current electromagnetic rotating speed w1 of the motor, and the multiplier 301 realizes the operation, so that the left side of the formula (2) is larger than the right side of the equation, and positive d-axis current is generated, and the flux-changing permanent magnet motor is prevented from demagnetizing. In addition, the d-axis voltage command Ud is set to zero, which does not result in the generation of a negative d-axis current.

The voltage command is applied to the motor in pulses by the pulser 303. The pulser 303 generates a pulse level OPpwm having a pulse width of one PWM period to several PWM periods, and it should be noted that the pulse width should not be so large that the motor generates a large current.

When the magnetizing state estimator 304 detects the falling edge of OPpwm, that is, when the pulse voltage loading ends, the dq-axis currents Id and Iq of the motor and the electromagnetic synchronous speed w1. of the motor are detected, and the d-axis incremental inductance L di is calculated according to the formula (1), as shown in the formula (3).

Ldi＝(w1*Lq*Iq-Ra*Id)/dId/dt…(3)

Based on the calculation result of the equation (3), the estimated value Φ est of the state of magnetization is estimated from the relationship curve between the state of magnetization and L di shown in fig. 5, and then the state of magnetization estimator 304 generates the set pulse signal OPrst to complete the calculation task of the tape speed re-projection control unit 204.

The operation commander 201 outputs the OPs level to the normal operation level N according to the OPrst set level. As shown in fig. 6, the vector control unit 203 receives the magnetization state observation value Φ est from the tape speed reconversion unit 204, estimates the present motor back electromotive force w1 × Φ est through the multiplier 602, and inputs the estimated value as a voltage compensation term to the q-axis current PI closed-loop control, so as to compensate the back electromotive force voltage during the current from zero to the normal current and prevent the generation of the inrush current.

The OPpwm signal is set to 1 to turn on the PWM pulse. In addition, the PI regulator 601 and the resistance compensation voltage in the dq-axis current control are common methods in the field of motor control, and are not described herein again.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.