Slip frequency detection for indirect field oriented control drives

The paper presents a new technique to detect the slip angular frequency in induction motor drives based on indirect field oriented control. According to the proposed technique, the slip frequency is calculated by processing the effects exerted by an additional high frequency signal on the zero sequence stator voltage. By measuring such a zero sequence voltage, it is possible to evaluate the air gap flux and to detect the slip frequency in order to implement an indirect field oriented control algorithm. According to the proposed approach, rotor time constant errors are not influent as in conventional field oriented control schemes. Therefore complex tuning or compensation techniques are not required. Simulations and experimental tests using have been performed in order to evaluate the consistency of the proposed approach.