Selection of the flux linkage reference in a direct torque controlled permanent magnet synchronous motor drive

A flux linkage reference control algorithm for the direct torque controlled (DTC) permanent magnet synchronous motor drive is presented. The proposed selection scheme minimizes the stator current in steady state. Minimizing the stator current does not give the lowest losses in PMSM since the iron losses increase with the increasing stator flux linkage. A selection scheme which decreases the total losses of the motor is also presented. Both control schemes are realized in rotor reference frame and therefore either measurement or estimation of the rotor angle is needed. An estimation method for this is presented. Laboratory experiments verify the operation of the control.