A method of controlling an alternating current, AC, voltage supplied to an AC motor for implementing a start-up sequence or a stopping sequence, comprising the steps of: operating (62, 64) the AC motor according to a first operating mode; entering a transition mode upon reaching a predetermined threshold, which may be a time interval or a commanded speed to the motor, when operating the AC motor according to the first operating mode, said transition mode including: determining a phase angle representing the current in the AC motor; determining a flux vector from at least one current signal and from at least one voltage signal, the flux vector having a magnitude and a phase angle representing the flux in the AC motor; determining a polarity of the torque in the AC motor according to the phase angles of the current and flux; and setting a conduction interval of an electronically controlled switching device used to connect the AC voltage to the AC motor according to the polarity of the torque, comprising: determining a desired conduction interval according to one of a magnitude of the current signal and a commanded speed to the motor; setting the conduction interval to a predetermined minimum value in response to a first polarity of the torque; and setting the conduction interval to the desired conduction interval in response to a second polarity of the torque; and thereafter, operating (70, 72) the motor according to a second operating mode until a desired operating speed is reached. operating (62, 64) the AC motor according to a first operating mode; entering a transition mode upon reaching a predetermined threshold, which may be a time interval or a commanded speed to the motor, when operating the AC motor according to the first operating mode, said transition mode including: determining a phase angle representing the current in the AC motor; determining a flux vector from at least one current signal and from at least one voltage signal, the flux vector having a magnitude and a phase angle representing the flux in the AC motor; determining a polarity of the torque in the AC motor according to the phase angles of the current and flux; and setting a conduction interval of an electronically controlled switching device used to connect the AC voltage to the AC motor according to the polarity of the torque, comprising: determining a desired conduction interval according to one of a magnitude of the current signal and a commanded speed to the motor; setting the conduction interval to a predetermined minimum value in response to a first polarity of the torque; and setting the conduction interval to the desired conduction interval in response to a second polarity of the torque; and determining a phase angle representing the current in the AC motor; determining a flux vector from at least one current signal and from at least one voltage signal, the flux vector having a magnitude and a phase angle representing the flux in the AC motor; determining a polarity of the torque in the AC motor according to the phase angles of the current and flux; and setting a conduction interval of an electronically controlled switching device used to connect the AC voltage to the AC motor according to the polarity of the torque, comprising: determining a desired conduction interval according to one of a magnitude of the current signal and a commanded speed to the motor; setting the conduction interval to a predetermined minimum value in response to a first polarity of the torque; and setting the conduction interval to the desired conduction interval in response to a second polarity of the torque; and determining a desired conduction interval according to one of a magnitude of the current signal and a commanded speed to the motor; setting the conduction interval to a predetermined minimum value in response to a first polarity of the torque; and setting the conduction interval to the desired conduction interval in response to a second polarity of the torque; and thereafter, operating (70, 72) the motor according to a second operating mode until a desired operating speed is reached.