Estimation of rotor and load angle of direct-torque-controlled permanent magnet synchronous machine drive

A dynamically well performing rotor and load angle estimation method for direct-torque-controlled (DTC) permanent magnet synchronous machines drives is presented. The rotor or load angle is needed as example in the limitation of the load angle. The method uses the same flux linkage estimate that is used in the core of the DTC and calculates the load and rotor angle directly from the motor equations. The effect of the flux linkage estimation method is analysed through simulation. Both the steady-state and dynamical measurement results are also provided, showing the good performance of the suggested method. The performance is adequate to be used as example in the limitation of the load angle in order to prevent the machine falling from synchronism.