A Fault Reclosing Control Method for a Multi-Branch Permanent Magnet Synchronous Motor

Abstract

The present invention discloses a fault reconnection control method for a multi-branch permanent magnet synchronous motor. Based on the vector control of the multi-branch permanent magnet synchronous motor, a reconnection decision controller and an on-line reconnection compensation controller are added. The on-line reconnection compensation controller further includes a branch inductance compensator and a back electromotive force compensator. The control method of the present invention enables the fault branch to be reconnected without disturbance and without stopping the operation of another branch after the fault of the fault branch disappears, thereby avoiding power interruption or jitter when the fault branch of the multi-branch permanent magnet synchronous motor drive system is reconnected, and improving the operation safety and reliability.

Description

Technical Field

[0001] The present invention belongs to the technical field of power electronics and electric drive, and particularly relates to a fault reconnection control method for a multi-branch permanent magnet synchronous motor. Background Art

[0002] In the fields such as electric vehicles and ship propulsion, permanent magnet synchronous motors are widely used. In some special application scenarios, in order to improve the reliability of drive or propulsion, multi-branch permanent magnet synchronous motors are adopted. Generally, a multi-branch permanent magnet synchronous motor takes three-phase, five-phase or six-phase as one branch, and has at least two independently operating branches.

[0003] At the same time, each branch is equipped with a corresponding frequency converter and control system. When one branch fails, the other branch can continue to operate, thus avoiding power loss. After the fault in the faulty branch is eliminated, it should generally be reconnected to operation.

[0004] Reconnection is divided into two methods: shutdown reconnection and online reconnection. The former will cause the system to lose power for a short time, while the latter will have problems such as overcurrent and torque fluctuation due to voltage disturbance introduced during reconnection. The present invention can realize automatic online reconnection of the branch without disturbance through automatic judgment of the reconnection time and voltage compensation, thereby improving the smoothness of system operation. Summary of the Invention

[0005] In order to realize automatic online reconnection after the recovery of the faulty branch of a multi-branch permanent magnet synchronous motor, the present invention proposes an automatic reconnection control method for a multi-branch permanent magnet synchronous motor, which can effectively suppress the disturbance during reconnection.

[0006] The technical solution adopted by the present invention to solve its technical problems is: a fault reconnection control method for a multi-branch permanent magnet synchronous motor, based on a permanent magnet synchronous motor vector control system with at least two independent vector control branches, and the permanent magnet synchronous motor vector control system is increased with a reconnection decision controller for generating a reconnection command and an online reconnection compensation controller for generating a reconnection compensation voltage; the reconnection decision controller latches the fault by a fault latch, determines the reconnection branch according to the latched fault flag and the current fault flag, collects the motor speed information, subtracts it from the preset reconnection speed with belt speed, and outputs a reconnection command when the result is negative; the online reconnection compensation controller consists of a side-branch induction compensator and a back electromotive force compensator, and the compensation voltages output by the two are added as the final compensation voltage, which is superimposed on the d-axis voltage and q-axis voltage of the reconnection branch.

[0007] Further, the side-branch induction compensator collects the d-axis current id, q-axis current iq and electrical angular frequency ω of the normal branch; multiplies the motor q-axis inductance Lq with iq and ω in sequence and takes the inverse as the compensation amount of the d-axis voltage; multiplies the motor d-axis inductance Ld with id and ω in sequence as the compensation amount of the q-axis voltage.

[0008] Further, the back electromotive force compensator multiplies the electrical angular frequency ω of the motor by the amplitude of the permanent magnet flux linkage as the amplitude of the compensation voltage; multiplies the electrical angular frequency ω by the angle compensation coefficient and adds π / 2 to obtain the compensation angle value; and performs a polar coordinate to rectangular coordinate transformation on the compensation voltage amplitude and the compensation angle value to obtain the compensation amount of the d-axis voltage and the compensation amount of the q-axis voltage.

[0009] The beneficial effects of the present invention are as follows: The control method of the present invention can automatically realize the online reconnection of the faulty branch of the multi-branch permanent magnet synchronous motor after the fault is restored, can suppress the current impact and torque fluctuation during the reconnection process, improve the smoothness of the motor operation, and is applicable to special ship electric propulsion, special vehicle drive, etc. with high requirements for drive reliability. Description of the Drawings

[0010] Figure 1 It is a multi-branch permanent magnet synchronous motor control system applying the control method of the present invention;

[0011] Figure 2 It is a schematic diagram of the reconnection decision controller of the present invention;

[0012] Figure 3 It is a schematic diagram of the online reconnection compensation controller of the present invention. Detailed Embodiment

[0013] Combined with the drawings, the present invention will be further described in detail below by taking a two-branch permanent magnet synchronous motor as an example.

[0014] Referring to Figure 1 As shown, in the two sets of independent vector control systems of the two-branch permanent magnet synchronous motor of the present invention, a reconnection decision controller and an online reconnection compensation controller are added, which are respectively used to generate reconnection instructions and reconnection compensation voltages.

[0015] Referring to Figure 2 As shown, the reconnection decision controller determines the reconnection branch and the reconnection timing according to the fault information, the branch operation state and the speed, and issues a reconnection instruction: uses a fault latch to latch the fault, and determines the reconnection branch based on the latched fault flag and the current fault flag; collects the motor speed information, subtracts it from the preset reconnection speed with belt speed, and outputs a reconnection instruction when the result is negative.

[0016] The compensation amount of the d-axis voltage generated by the branch inductive compensator and the compensation amount of the d-axis voltage generated by the back electromotive force compensator are added to obtain the final compensation amount of the d-axis voltage as the initial value of the d-axis voltage of the branch to be reconnected. The compensation amount of the q-axis voltage generated by the branch inductive compensator and the compensation amount of the q-axis voltage generated by the back electromotive force compensator are added to obtain the final compensation amount of the q-axis voltage as the initial value of the q-axis voltage of the branch to be reconnected.

[0017] Refer to Figure 3 As shown, the online reclosing compensation controller consists of a branch inductive compensator and a back electromotive force compensator. The compensation voltages output by the two are added together as the final compensation voltage, which is superimposed on the d-axis voltage and q-axis voltage of the reclosing branch: when reclosing is required after the fault recovery of branch one, the branch inductive compensator collects the d-axis current id2, q-axis current iq2 of branch two and the electrical angular frequency ω of the motor; multiply the motor q-axis inductance Lq with iq2 and ω in sequence and take the negative value to obtain the compensation amount ud2 of the d-axis voltage; multiply the motor d-axis inductance Ld with id2 and ω in sequence to obtain the compensation amount uq2 of the q-axis voltage.

[0018] The back electromotive force compensator multiplies the electrical angular frequency ω of the motor with the amplitude λ of the permanent magnet flux linkage to obtain the amplitude us of the compensation voltage; multiplies the electrical angular frequency ω with the angle compensation coefficient K, and adds π / 2 to obtain the compensation angle value β; performs a polar coordinate to rectangular coordinate transformation with the amplitude us of the compensation voltage and the compensation angle value β to obtain the compensation amount ud3 of the d-axis voltage and the compensation amount uq3 of the q-axis voltage.

[0019] Add ud2 and ud3 to obtain the final compensation amount ud4 of the d-axis voltage. Add uq2 and uq3 to obtain the final compensation amount uq4 of the q-axis voltage. The d-axis voltage and q-axis voltage output by the original current loop PI regulator of branch one are ud0 and uq0 respectively. Add ud0 and ud4 to obtain ud1, which is used as the d-axis voltage after compensation of branch one. Add uq0 and uq4 to obtain uq1, which is used as the q-axis voltage after compensation of branch one.

[0020] The above embodiments only illustratively explain the principles and effects of the present invention, as well as some applied embodiments. For those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention.

Claims

1. A fault re-injection control method for a multi-branch permanent magnet synchronous motor, based on a permanent magnet synchronous motor vector control system with at least two independent vector control branches, characterized in that: The described permanent magnet synchronous motor vector control system further includes a reclosure decision controller for generating a reclosure command and an on-line reclosure compensation controller for generating a reclosure compensation voltage; the reclosure decision controller uses a fault latch to latch the fault, determines the reclosure branch according to the latched fault flag and the current fault flag, collects the motor speed information, subtracts it from the preset belt speed reclosure speed, and outputs a reclosure command when the result is negative; the on-line reclosure compensation controller consists of a branch inductive compensator and a back electromotive force compensator, and the compensation voltages output by the two are added together as the final compensation voltage, which is superimposed on the d-axis voltage and q-axis voltage of the reclosure branch; the branch inductive compensator collects the d-axis current id, q-axis current iq and electrical angular frequency ω of the normal branch; multiplies the motor q-axis inductance Lq by iq and ω in sequence and takes the negative value as the compensation amount of the d-axis voltage; multiplies the motor d-axis inductance Ld by id and ω in sequence as the compensation amount of the q-axis voltage; the back electromotive force compensator multiplies the electrical angular frequency ω of the motor by the permanent magnet flux linkage amplitude as the compensation voltage amplitude; multiplies the electrical angular frequency ω by the angle compensation coefficient and adds π / 2 to obtain the compensation angle value; performs a polar coordinate to rectangular coordinate transformation with the compensation voltage amplitude and the compensation angle value to obtain the compensation amount of the d-axis voltage and the compensation amount of the q-axis voltage.

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