Design Of Highspeed Single Phase Brushless DC Motor System

The Brushless motor structure can be divided into single phase and multi-phase according to the structure of winding.Compared with multi-phase brushless motor,Single phase brushless motor has simple structure,small volume,low cost.It has prominent advantages in the Fan application.This paper design the single phase brushless motor and the corresponding control system used in handheld vacuum cleaner in order to achieve the goal of big air volume and high efficiency.In order to obtain compact mechanical,the shape of the stator silicon steel sheet is made with u-shaped structure.According to the needs of the control result,select the bipolar winding structure,winding in parallel.Starting is very difficult if the single phase brushless dc motor is stationary.In order to solve the problem,design the pole shoe structure of uniform air gap,reduced the motor torque fluctuation at runtime.Structure of splicing can create eccentric torque needed for static startup,and can make the stator winding on the winding mode alone,improve the production efficiency.Under the specific size,to achieve the goal power 350 W,speed 90000 rpm,With simulation comparison,determine the magnetic steel material and rotor structure.Under the situation of high speed operation,the centrifugal force is strong,in order to avoid magnetic breakdown,design the rotor core structure of the fitting,prevent the damage of magnet steel during the process of axis and the magnetic steel assembly;Add a layer of rubber sets outside,both guarantee no clearance between the machine coordination,and prevent the magnetic steel splash.Design the double unilateral bearing structure,it will get the adaptive concentricity and decrease bearing friction heat,low the temperature,improve life expectancy.In order to need the specific demand,suitable type of hall sensor is very important,TO-92 encapsulation are susceptible to vibration damage,design the special base for hall sensor to ensure the safety of pins.Based on the motor commutation principle,Analyze the relationship between position sensor placement and back electromotive force,obtain the general rule of position sensor placement.The design of the control system consists of system framework,the key of hardware circuit and software logical framework.Vacuum application works with high speed and low speed.By comparison of different control method,combining the resources of the hardware resources and MCU,select the appropriate control strategy for PWM.In order to achieve good control effect,the use of multiple algorithms,including startup square wave commutation for the first step,conduction time and off time control,commutation in advance,the constant power control.The experimental results show that the control performance is good.