Initial rotor position detection for delta-connected synchronous reluctance motor

In this paper, an initial rotor position detection approach for the delta-connected synchronous reluctance motor is proposed. This method estimates the rotor angular position by applying voltage pulses to the stator windings with appropriate switching sequences of a PWM inverter at standstill condition. It only needs the 3-phase motor line currents measurement to determine the initial position of the rotor and thus does not require any knowledge of machine parameters. This technique is based on the theory that the stator self and mutual inductances are functions of rotor positions, and the relationship between the currents and the rotor position is presented with equations. The equivalent circuits of the different conduction modes are analyzed and the experimental results have been verified, demonstrating that the technique can provide an accurate initial rotor position which can be further used in the sensorless control.