Abstract: A variable speed controller is provided which utilizes a combination of pulse width modulation and fixed pulse control, such as a conventional six-step control, in order to generate multiphase sinusoidal power signals for use by downhole wellbore equipment, such as electrical submersible pumps. A controller is utilized to monitor at least one DC voltage level of the rectifier and/or inverter circuit of a variable speed controller. The DC level is compared to an optimum DC level. A triggering threshold is established. Once the triggering threshold is surpassed, the controller is utilized to switch between a conventional six-step mode of control and a pulse width modulation mode of control in order to better respond to a positive transient voltage condition. The pulse width modulation mode of operation provides for real time counteracting of the positive transient condition.