中文摘要：

提出L/H控制策略,扩展基于sensorless技术的无刷直流电动机调速范围.将电机的速度频域划分为低速运行区和高速运行区.电机在低速时,采用反电势逻辑电平积分法提供换相信号,高速运行时的换相信号则通过反电势三次谐波法获得.同时,提出了两种控制法的切换方式.仿真和实验结果表明,该控制策略在低速和高速区均能给出比较准确的换相时间,且两种控制方法切换良好,实现了无刷直流电动机在无位置传感器情况下的广域调速.

英文摘要：

A control strategy of low/ high conversion was proposed to expand the speed range of brushless DC motorbased on sensorless techniques. The speed domain of the researched motor was divided into high speed and low speed.When the motor operates at low speed, back-EMF logic level integration was put forward to acquire commutation signalswhile at high speed the commutation signals were acquired by third harmonic back-EMF. Meanwhile, conversion mode be-tween the two patterns was proposed. The experiment shows the strategy can achieve highly accurate commutation time bothat low speed and high speed, and conversion method works well. The proposed strategy can widely control the speed ofbrushless DC motor without position sensor.