A novel digital control technique for brushless DC motor drives: current control

This paper presents a digital control technique for trapezoidal brushless DC (BLDC) motor drives. This novel digital control treats BLDC motor as a digital system and regulates speed with the help of two predefined state variables, state-1 designed for high-speed operation and state-2 defined for low-speed operation. A comparator compares actual speed with set speed and then switches between appropriate states. Thus, task of the digital control is to deliver right amount of power to the motor by right numbers of state-1 and state-2 operations so that average power delivery matches required power. It needs few logic gates and comparators to implement digital control, thus making it extremely simple and easy to develop a low cost application specific integrated circuit (ASIC) for speed control of BLDC motor drives. Simulation and experimental results are presented to describe and verify the proposed technique