A motor drive system includes a power sub-assembly that comprises power electronic components and driver circuitry for controlling gate drive signals to the power electronic components. A control sub-assembly is removably mounted to the power sub-assembly and comprises control circuitry for implementing a motor control routine for control of an electric motor. In operation, all control signals originate in the control-subassembly, and are transmitted via mating connectors to the power sub-assembly for driving the motor.