A vector field-weakening control system for permanent magnet synchronous motors in electric drive systems

Abstract

The invention discloses a permanent magnet synchronous motor vector field weakening control system of an electric drive system. The system consists of a current closed-loop adjustment module, a modulation ratio deviation calculation module, a current characteristic point setting module, a current compensation vector angle calculation module, and a current compensation vector It is composed of an amplitude calculation module, a current compensation vector calculation module and a current command correction module. The present invention takes the three-phase short-circuit current of the motor as the end point of the field-weakening adjustment, and when the voltage saturation occurs, the motor control system can be withdrawn from saturation; the end of the motor is powered by the power battery bus due to the inverter, and the voltage at the end will not As low as zero, there is a large margin to deal with abnormal factors; by introducing dq current and correcting at the same time, the pressure of anti-voltage saturation can be distributed to dq current to avoid excessive output torque deviation caused by excessive single-axis current adjustment . While ensuring the safety of the driving system, the invention minimizes the influence of the field weakening control link on the output torque of the driving system as much as possible.

Description

technical field [0001] The invention belongs to the field of permanent magnet synchronous motor control, in particular to a vector field weakening control system of a permanent magnet synchronous motor of an electric drive system. Background technique [0002] In the vehicle embedded permanent magnet synchronous motor (IPMSM) control system, due to the inevitable change of the controlled object-IPMSM in the actual application scene, the pre-cured control parameters in the control program are invalidated, resulting in the motor running at high speed and weakening the field. Insufficient voltage causes voltage saturation, which jeopardizes the stability of the motor drive system. [0003] IPMSM has the characteristics of high power density, wide operating range and high efficiency, so it is widely used in the driving motor of electric vehicles. Its torque equation is: [0004] [0005] Among them, T e is the electromagnetic torque of the motor; P n is the number of pole ...

AI Technical Summary

Problems solved by technology

[0017] 1. When the motor is in mass production, the process and materials will inevitably lead to the inconsistency of the motor;

[0018] 2. The deviation of the resolver offset of the motor will lead to the deviation of the magnetic field orientation on the control, which will cause the actual dq current in the motor to be inconsistent with the expected current command, even when the current regulator is working normally;

[0019] 3. Changes in ambient temperature will affect the flux linkage of permanent magnets. When the temperature drops, it will cause rise, causing the calibrated dq current command to no longer meet the voltage limit

but when When , continue to increase the negative i d , it will make V q The reverse increase will lead to a further increase in the output voltage, which will cause the voltage saturation to be more serious

Therefore, when using this method, you must ensure that However, in vehicle motor control, if this limitation is added, the reluctance torque of the motor in the high-speed region will not be fully utilized, sacrificing the performance of the motor

[0022] In the above scheme, reduce i when the voltage is saturated d The method can deepen the weak magnetic field and make the motor exit the voltage saturation state, but this method has a greater impact on the output torque, because only by correcting i d , requires a larger i d The combination of the correction amount dq and current changes greatly so that it has a great impact on the output torque

Literature (T.M.Jahns, "Flux WeakeningRegime Operation of an Interior Permanent-Magnet Synchronous Motor Drive", IEEE Trans.on Ind.Appl., vol.IA-23, no.4, pp.55-63, 1987) proposed a This reduces the i in the field weakening area q method, but only adjusting a single current also faces the problem of a large impact on the output torque mentioned in 2; no good existing technology has been found to be able to effectively deal with the problem of voltage saturation, and as far as possible May have little effect on output torque

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