单电阻电流采样的三相电机不完全DPWM方式

The Incomplete DPWM Mode for Three-phase Motor With Single-resistor Current Sampling

为解决单电阻电流采样的三相电机控制系统低速运转中不连续脉宽调制(DPWM)方式使电流采样恶化的问题,提出一种不完全DPWM方式。不完全DPWM方式的调制波峰值随电机转速变化,与直流母线电压正值或负值留有一定距离,在整个调制波周期均进行脉宽调制(PWM)。为避免直接切换到DPWM方式的电流波动,提出由不完全DPWM方式向DPWM方式切换的过渡过程,调制波峰值按预定斜率慢慢达到直流母线电压正值或负值。实验证明在电机低速时采用不完全DPWM方式及向DPWM方式切换的过渡过程,能有效改善电流采样恶化及DPWM方式切换时的电流波动问题。

In order to solve the problem that the discontinuous pulse width modulation(DPWM) mode worsens the current sampling in the low-speed operation of the three-phase motor control system with single-resistance current sampling,an incomplete DPWM mode is proposed.The peak value of the modulation wave in the incomplete DPWM mode changes with the motor speed and there is a certain distance from the positive or negative value of DC bus voltage,pulse width modulation(PWM) is carried out in the whole modulation wave cycle.In order to avoid the current fluctuation caused by direct switching to DPWM mode,a transition process from incomplete DPWM mode to DPWM mode is proposed,the peak value of modulation wave reaches the positive or negative value of DC bus voltage gradually with a preset slope.Experiments show that the application of incomplete DPWM mode at low speed and the transition process to DPWM mode can effectively improve the deterioration of current sampling and the current fluctuation during DPWM mode switching.