Accessory motor drive power supply system for an electric vehicle

Abstract

An electric vehicle accessory motor drive power supply system ( ) that utilizes a single power supply design to provide efficient variable speed motor control to both brushless and brush-type DC motors ( ). The power supply system includes at least one of each type of motor along with a first DC-DC converter ( ) that provides operating power to the brushless motor ( ) and a second DC-DC converter ( ) that provides operating power to the brush-type motor ( ). Both converters ( ) have a power input ( ) connected to the electric vehicle's high voltage bus ( ) and each includes a data input ( ) for receiving a speed control signal (SC) indicative of desired motor speed, as well as an output ( ) for providing a motor drive signal to its associated DC motor ( ). Each of the converters ( ) is operable in response to its received speed control signal to convert operating power from the high voltage bus ( ) into a lower voltage variable motor drive signal that is provided to its associated motor ( ) via its output ( ). The variable drive signal can be either a variable DC voltage signal or a pulse-width modulated signal. With this arrangement, a single converter design, including a single speed control interface, can be utilized to operate both brush-type and brushless motors. Furthermore, the system permits more efficient operation of the brushless motors since it obviates the need for speed control electronics on the motor itself and therefore eliminates the relatively inefficient use of cascaded PWM stages.