Dual closed loop controller of bus stepper motor based on Back-EMF

With the ever-increasing requirement of safety for vehicle, the adaptive headlamp concept is put forward. The cost and maturity level for adaptive headlamp still are the most important matter. In this research, a new senseless dual closed loop stepper motor control algorithm is presented to solve the velocity, torque, cost and position precision issues in adaptive headlamp system, which includes the stall detection and back-EMF measurement for feedback. The position loop with stall detection and compensation based on back-EMF is presented to avoid step loose caused by disturbance, when the disturbance appear which increases the robust of operation; the current loop with variable parameters fuzzy logic is proposed to modify the current in coil to cope with the potential load variation. The compensation of load variation makes stepper motor smaller and cheaper. The simulation result shows that dual closed loop algorithm can enhances the system´s robustness and application scope of stepper motor.