Abstract— A position sensorless Surface Permanent Magnet
Synchronous Motor (SPMSM) drive based on flux angle is
presented in this paper. The motor equations are written in
rotor fixed d-q reference frame. A PID controller is used to
process the speed error to generate the reference torque current
keeping the magnetizing current fixed. The estimated stator flux
using Recurrent Neural Network (RNN) is used to find out the
rotor position. The flux angle and the reference current phasor
angle are used in vector rotator to generate the reference phase
currents. Hysteresis current controller block controls the
switching of the 3-phase inverter to apply voltage to the motor
stator. Simulation studies on different operating conditions
indicate the acceptability of the drive system. The drive system
only requires a speed transducer and is free from position sensor
requirement. The proposed control scheme is robust under load
torque disturbances and motor parameter variations. It is also
simple and low cost to implement in a practical environment.