Magnetic flux compensating torque control method suitable for general purpose inverters with superaudible switching frequencies

A novel torque control method which is suitable for general-purpose induction motor variable speed devices driven by superaudible frequency PWM (pulse width modulation) inverters is described. In the torque control, the primary magnetic flux reference is compensated, using only current sensors, on the basis of the inverter angular frequency and the slip angular frequency, so that motor torque can be generated according to load torque. The superaudible frequency PWM signals are generated by divisions of duration times of the voltage vectors, determined on the basis of the primary magnetic flux reference. Experiments showed that high-performance torque characteristics suitable for general-purpose inverters could be obtained by this method.<>