Design Of Sensorless Controller Of Brushless DC Motor For Hand-push Lawn Mower

At this stage,the hand push the lawn mower is widely used in the green lawn maintenance.As the core part of brushless DC motor,the control quality will directly affect the performance of the hand-pushed lawn mower.Aiming at hand push lawn mower in brushless DC motor control problems such as the low utilization rate of power supply,start is not smooth,we design a brushless DC motor sensorless controller,using high frequency square wave injection start-up and vector control method,has reached the motor start and work condition of stability control purposes.In the process of brushless dc motor start,in view of the brushless dc motor rotor position precision is low,in the process of start acceleration phase poor stability problem,this paper proposes a high frequency square-wave brushless dc motor start injection strategy.Using lawn mower motor startup can be divided into two stages of slow and fast method,under different sampling points extraction alpha beta shafting of high frequency current response and used to estimate rotor position.Paper on the basis of the positive and negative pulse injection,also puts forward a motor startup d axis polarity judgment method for the first time.In MATLAB simulation module setup,validation under this algorithm of brushless dc motor rotor position estimation accuracy,and the ability to load startup.In the working state of the brushless dc motor,design the sliding mode speed controller for speed regulation;Using the sliding mode observer + phase-locked loop algorithm to estimate the rotor position.And tested in MATLAB simulation model were established,the sliding mode speed controller adjust ability and anti-interference ability,and the Angle of the sliding mode observer under load and speed estimation accuracy.Finally,design the hardware control circuit experiment analysis.The experimental results show that the improved method can accurately judge the rotor polarity during the starting process of the motor.The optimized integrated current processing strategy can be used to estimate the rotor position effectively and improve the accuracy of estimation.In the working process,the current curve is stable and the error of Angle estimation is small under no load and load condition.In applying under random load,sliding mode speed controller can rapid response,improve the robustness of the system.