永磁同步电机电流环频率响应改进策略研究

Current loop frequency response improvement strategy research for permanent magnet synchronous motor control system

针对永磁同步电机矢量控制电流环内存在的固有延迟环节,如电流采样、占空比计算、逆变器死区效应及数字控制延时等。在同步旋转坐标系下引入电流解耦项jωrL,分析制约电流环频率响应能力的主要迟滞因素,并对比不同电流采样时刻与脉宽调制(pulse width modulation,PWM)占空比更新时序对电流环频率响应的影响。提出了一种新的电流采样时机和更新输出PWM信号模式,在半个载波周期内优化采样、计算和输出时序,减小了电流环固有延时等待时间。在载波频率不变的前提下,提高电流环动态加速过程中电流的跟踪性能。仿真和实验结果与理论分析基本吻合,电流环的频率频带带宽提高了近一倍,表明该策略的有效性和正确性。

Considering the inherent delay existing in the current loop of permanent magnet synchronous motor,such as the current sampling,duty ratio calculation,inverter dead-time effect and digital control delay,etc,it introduces the current decoupling jωr L in the synchronous rotating reference frame,conducts the analysis of main hysteresis factor restricting current loop frequency response ability,and comparison of impact of different current sampling time and renewal of the PWM duty cycle on current loop frequency response.This paper proposed a new current sampling time and updated the output PWM signal model.The optimization calculation and output sequence in half a carrier cycle sampling were achieved to reduce the current loop inherent delay.The current loop current in the process of dynamic tracking performance was improved under the premise of the invariable carrier frequency.The simulation and experimental results are in accordance with the basic theoretical analysis,and the current loop bandwidth of frequency band can be nearly increased by double.