Application of an average current control method in Double-loop control systems of brushless DC motor

Double-loop control systems of brushless DC motor (BLDCM) yield a combination of desired characteristics including simplified control structure, high speed accuracy, wide operating speed range and fast dynamic response. The current loop is very important for system performance. Its linearity is influenced by the accuracy of feedback current. The cost of detecting currents in three windings is higher, and most methods based on shunt-current reaction are nonlinear. An average current control method of sampling the dc-link current at the center of the Pulse-Width Modulation (PWM) on-time interval can overcome the above limitations. Average stator current can be regulated by the average current control method. Simulation results demonstrate this method is very effective and can make systems obtain basically same performance compared with the method of detecting currents in three windings.