The power electronics motor drive comes in two major types: (1) the servo motor drive to control the precise speed and position of the rotor and (2) the motor drive for varying motor speed in response to a desired change in the load output, such as the air ventilation and fluid pumping rate. The response time and precision in position are important in the servo drive but not in the variable-speed motor drive. Our interest in this chapter is primarily focused on the variable-speed motor drives.