These days, numerous motors are used in automobile application for the convenience and comfortable ride. Several requirements are demanded to the motors such as small size, light weight, high power density and eco-friendly. Among various motors, brushless DC motor is one of the most attractive motors to satisfy these requirements. Since the brushless DC motor does not have commutator and brush, the motor is able to have long life time and the high ratio of power to weight. However, commutation torque ripple is generated in brushless DC motor drives. Since the torque ripple causes acoustic noise and mechanical vibration, the convenience and comfortable ride are not able to be ensured. This paper proposes the reduction technique of commutation torque ripple in brushless DC motor drive. The proposed method modulates the both current slopes of the incoming and the outgoing phase. The incoming phase current has upward slope, and the outgoing phase current has downward slope. This modulation is based on the control of duty ratio affected by commutation interval. Typically, the commutation interval is settled by motor parameter so that the detection of the interval is required. Since proposed method controls commutation interval, it does not require control loop and sensing circuit for the detection. Hence, low cost motor drive system can be achieved for brushless DC motor. The motor drive system with the proposed technique is implemented by digital controller employed digital signal processor. Brushless DC motor drives with upper pulse width modulation. The experimental results verify the reduction of commutation torque ripple in brushless DC motor drive system.