A method is provided for controlling a transition between over-modulation and six-step pulse width modulation (PWM) modes in an electrical system having a polyphase electric machine driven by a polyphase output voltage of a power inverter. The method includes receiving input values via a PWM controller, including a holding angle, rotational speed of the electric machine, and present voltage angle of the power inverter. The method includes calculating a future voltage angle of the inverter using the input values and adjusting pulse widths of a baseline PWM pulse train based on a duty cycle of the power inverter. The power inverter output voltage is controlled during the transition using the adjusted baseline PWM pulse train, such that the transition is continuous. An electrical system includes the power supply, power inverter, electric machine, and the PWM controller, the latter of which is configured to execute the method.