基于电流波形检测法的开关磁阻电动机无位置传感器控制

开关磁阻电动机(SRM)在采用电压PWM控制方式时,通常在定、转子齿极开始重叠位置处出现峰值电流。传统电流梯度法利用该峰值电流的前后电流微分值符号变反的特征,通过微分和过零检测电路得到转子位置,但存在检测电路参数设计繁琐,低速运行时不易获取正确的转子位置以及容错能力较差等缺点。为此,提出了一种基于电流波形检测的转子位置估算方法。该方法通过比较前后时刻电流大小,在该相关断时刻确定该相电流峰值及其对应的时间,并与前一相峰值电流对应时间共同计算确定后一相的关断时间。随后通过给定开通角,计算出开通角对应脉冲数,再通过比较当前计数值与该开通角对应的脉冲数,确定当前相或后一相的开通时间。该方法不仅保留了不依赖SRM参数的优点,而且无需微分、过零检测等外围电路,在低速运行时也能够得到正确的转子位置且具有较强的容错能力。通过基于该方法搭建的SRM无位置传感器控制系统的DSP驱动实验,证明了所提方法的可行性和有效性。

Sensorless Control of Switched Reluctance Motor Based on Current Waveform Detection Method

In case of switched reluctance motor( SRM)using voltage PWM control mode,the peak current usually appears at the initial overlapping position between the stator and the rotor poles. In the conventional current gradient method,the rotor position can be estimated through the differential and zero crossing detection circuit by using the characteristics of the sign inversion of the current differential value before and after the peak current. However this method has such disadvantages as tedious parameters design for differential and zero crossing detection circuit,difficulty in obtaining the correct rotor position under the low-speed region,and poor fault tolerance ability. For these reasons,a current waveform detection based rotor position estimation method is proposed in this paper. This method confirms the phase peak current and the corresponding time in the turn-off time by comparing the current values before and after the present moment,then calculates and confirms the turn-off time of the next phase by combining the time of the previous phase peak current. Then the pulse number which corresponds to the opening angle can be calculated by given the opening angle,and then the turn-on time of the present or the next phase can be confirmed by comparing the present count value with the pulse number which corresponded to the opening angle. Compared to conventional current gradient method,the proposed method not only retains the merit of conventional method,such as independent of SRM parameters,but also needs no differential and zero crossing detection peripheral circuits. Meanwhile,the proposed method could get more correct rotor position and have better fault tolerant ability at low speed region. Through DSP based experiments on the SRM sensorless control system which is constructed according to the proposed method,the feasibility and validity of the proposed method is verified.