Patent attributes
Brushless direct-current (“BLDC”) motor and control for a power tool. A BLDC motor of a power tool is controlled in either a pulse-width modulation (“PWM”) commutation mode or a centerline commutation mode. When the motor is rotating slowly, the motor is operated using PWM commutation. When the motor is rotating at a speed greater than a threshold speed value, the operation of the motor is transitioned to the centerline commutation mode. When operating in the centerline commutation mode, the high-side field-effect transistors (“FETs”) and low-side FETs can each be used for motor speed control. By switching between speed control using the high-side FETs and speed control using the low-side FETs, the heat generated by freewheeling currents can be approximately evenly distributed among the high-side and low-side FETs.