一种统一的无刷直流电机直接反电动势法

A Unified Approach to Direct Back EMF Detection for Brushless DC Motor

无刷直流电机直接反电势法研究已经得到了比较广泛的开展,但只适用于上管调制、下管恒通的控制方式。在研究无刷直流电机传统模型的基础上,根据无刷直流电机的工作原理,构建了无刷直流电机的简化模型,由此简化模型分析了不同PWM技术断开相端电压的特点,提出了通过在PWM开通期间采样断开相端电压与二分之一的母线电压相比较检测反电动势过零点的方法,并进行了样机实验。实验结果表明:提出的方法能在很宽的电机速度范围内,精确地获得不受PWM影响的反电动势过零点。

The direct back electromotive force（EMF） detection method by synchronously sampling the motor back EMF during the pulse width modulation （PWM） off time has been extensively applied in a sensorless brushless DC （BLDC） motor drive. But this direct back EMF sensing scheme is only suitable for the mode whose high side switch is PWM and low side switch is on. On the basis of the research into the traditional model and the working principle of the brushless DC motor,a simplified model of the brushless DC motor is formulated,by which an analysis of the voltage characteristics under different PWM technologies is made. A method of obtaining the back EMF zero-crossing information by comparing the open phase voltage with one half of DC link voltage during PWM on time is proposed and experimented on the prototype. The experimental results show that the proposed control algorithm does satisfactory performance over a wide operation range under various PWM modulation modes.