A new single current strategy for high-performance brushless DC motor drives

For closed-loop current control of brushless dc (BLDC) motors, instantaneous phase currents are measured using appropriate current sensors. Such sensors are often bulky, heavy, and expensive, making them appealing for elimination. Likewise, the use of two or more separated sensors can cause undesirable imbalances in the phase currents as well as pulsating torque due to mismatched in the current sensor sensitivities. To overcome these problems, a new single current strategy for high performance BLDC motor drives is proposed. It is based on estimation and regulation of phase currents, using two single sensors for dc-link voltage and current. In this method, the phase currents are reconstructed in a two-stage process including estimation and regulation. Estimation is based on dynamic motor model, while regulation relies on the inverter switches states and the measured dc-link current. Besides, to access better dynamic response characteristic of the motor speed, Particle Swarm Optimization (PSO) has been used to regulate the PID parameters of speed controller. The effectiveness of proposed system has been validated by comparative studies and simulation results.