Position Estimation Scheme Of Single-Phase Hybrid SRM Using Back-EMF

Due the advantages such as simple structure, high efficiency, strong tolerance property and flexible control strategy, the switched reluctance motor(SRM) has drawn lots of attention of the industry. The application scope of SRM has covered aerospace, oil field and electrical vehicle(EV) and so forth. For general application, the multi-phase SRM is more popular to be employed considering the self-start ability, torque dead zone and torque ripple issues. However, it also causes high converter cost and reduced system efficiency by bring more switching loss especially during high speed operation. This paper introduces a kind of single-phase hybrid SRM(HSRM) driving system and contrasting with multi-phase SRM system, it adopts single-phase converter which can low the switching loss as much as possible. Besides, comparing with conventional single-phase SRM, the HSRM has the merits such as reduced torque ripple, self-start ability and no torque dead zone.It is apparent that, the SR motor requires position feedback for motor phase commutation. In order to assure the regular running of the motor, accurate knowledge of rotor position is indispensable. In many cases, this requirement is addressed by using position sensors, such as encoders or Hall sensors, etc. However, for size reduction, cost minimization and harsh environment operation, the sensorless technique is especially crucial.In this paper, firstly, the basic structure of the single-phase HSRM is presented in detail. Then combining with the simulation analysis of MAXWELL/ANSOFT, the operating principle, electromagnetic property and driving system of the motor is introduced. Then the mathematical model of the motor is described and the characteristic curve of the permanent material in motor stator is given. Basing on the operating principle, a novel position estimation scheme using back-EMF is proposed to achieve the sensorless running of the single-phase HSRM system. In the proposed scheme, the determination of the turn off position in the first electrical cycle is proposed together with the determination of turn on/off position in general operation region. Afterwards, the specific block diagram and flowchart is given to describe the proposed position estimation process. Then according to the mathematical model, a simulation model with proposed position estimation scheme is built to verify the rationality and practicability of the proposed ideal. Lastly, the hardware and software constitution of the experimental platform is introduced. The no-load and load test waveforms are displayed which demonstrate the validity, reliability and robustness of proposed scheme.