Improved current prediction control method of switched reluctance motor

Abstract

The invention discloses an improved current prediction control method of a switched reluctance motor, and belongs to the technical field of switched reluctance motor control. A system for completing the control method comprises a microcontroller, a three-phase switched reluctance motor, a power converter, a PWM driving unit, a current sensor, a current detection filter circuit and a position detection unit; the main circuit of the PWM driving unit is of a three-phase asymmetric half-bridge structure; According to a switched reluctance driving system, a double-closed-loop control system is adopted, an outer loop employs rotating speed loop control, an actual rotating speed is calculated through a position detection unit, and a reference current is obtained through a PI controller after the difference between a reference rotating speed and the actual rotating speed is obtained; an inner loop employscurrent loop control, the relation among inductance, current and a rotor position angle is obtained through finite element analysis, and corresponding phase inductance values and control frequency of the motor are obtained through phase current and the rotor position angle through a two-dimensional look-up table method. A corresponding predicted current interval is obtained through the above conditions, and then the precise time of each switching state is calculated to serve as a PWM conduction signal of a conduction phase to be used for driving the motor.

Description

technical field [0001] The invention belongs to the technical field of switched reluctance motor control, and mainly aims at the problem that the current is difficult to control within the limited current sampling frequency and control frequency caused by the nonlinear characteristics of switched reluctance motor inductance, and a method for improving the accuracy of current control. Background technique [0002] A switched reluctance motor (Switched Reluctance Motor, SRM) has excellent characteristics such as low manufacturing cost, simple structure of the stator and rotor, and good fault tolerance. The motor speed control system generally adopts double closed-loop control of speed and current. Commonly used current loop control methods include current PI control, model predictive current control and other methods. [0003] The current PI control principle is simple, easy to use, strong adaptability, and less sensitive to current changes of the controlled object. When pay...

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Problems solved by technology

[0004] However, the current PI control ignores the nonlinear characteristics of the switched reluctance motor, so that the current control has a certain overshoot

Current PI control cannot meet the requirements when the motor control has high speed and control accuracy requirements, and there is still no effective theory to determine the values ​​of various parameters for PI parameter setting at this stage. In practice, a large number of simulations and experiments are usually relied on. adjustments, which again presents some problems for motor control

Model predictive control also has some disadvantages

A large amount of calculation is a disadvantage, which puts high demands on the computing power of the control board

Although rolling optimization is possible, the control accuracy is poor, and the control is not delicate enough to achieve high control accuracy and cannot eliminate the static error of the system

At the same time, there is a high precision requirement for the sampling time, the sampling frequency is low, and the motor cannot be effectively controlled at about 10kHz

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