Practical implementation of the sensorless field oriented control of a PMSM for wide speed range

The aim of this paper is to present the implementation of the sensorless field oriented control of a surface mounted permanent magnet machine for wide speed range. At standstill up to a certain low speed range a high-frequency carrier signal based model is employed. The injected test signal is a rotating voltage vector in the stator reference frame and the rotor angle is estimated by filtering and demodulating the resultant high frequency currents. A modified PWM signal generation algorithm is implemented to reduce the dead-time extremely, in order to overcome the effects of the inverter non-linearity in the estimation process. A hybrid flux estimator based on the voltage model of the machine, dominant at higher speed, combined with the signal injection model is used, also a smooth transition between them is achieved. The experimental measurements show the effective performance of the position estimation method, which is implemented on a low cost, fixed-point DSP.