Sensorless speed control of symmetrical triple-star nine-phase Interior Permanent Magnet machines

This paper presents a sensor-less method to control triple-star nine-phase Interior Permanent Magnet (IPM) machines based on a decoupled machine model. The decoupled model removes the control complexity of the drive caused by the coupling inductance terms between different sets of three-phase windings of the triple-star machine. The rotor position is estimated using high frequency voltage injections into the stator fifth sequence circuit of the machine which is non torque producing. The control strategy which seeks to minimize stator copper loss (equivalently, the peak phase current) is set forth and tested by simulations using the full order coupled model of the machine. It is further validated with experimental results.