New modulation encoding techniques for indirect rotor position sensing in switched reluctance motors

Two novel indirect switched reluctance motor (SRM) rotor position (RP) sensing schemes based on winding current amplitude and phase modulation are presented. An off phase is supplied with a stiff sinusoidal carrier voltage from the sensing circuit to be modulated by an RP dependent phase inductance function. The modulated signal is decoded to obtain the information signal and is calibrated to obtain the RP angle continuously. A combination of phase modulation and amplitude modulation encoder techniques was designed and tested on a 5 hp three-phased 6-4 SRM over a wide range of speed. The position detection scheme kept excellent track of the rotor angle continuously under both load and no-load conditions. This scheme is extremely robust to switching noise present in the sensing phase due to mutually induced voltages.<<ETX>>