Abstract 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.
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2016, Vol. 31 
