The Research On The Control Strategy Of BLDC Motor Based On Three-level Inverter

In recent years, BLDC Motor with its superior performance has occupied animportant position in the automotive field, appliance, aerospace and other industries.Control technology of BLDC Motor is also developing more mature. Research ofBLDC Motor is now mainly focus on three aspects: Research on control technologyof without position sensor; Research of torque ripple control; Intelligent control.Now the domestic research is mainly for small power BLDC Motor. With thedevelopment of power electronic technology and permanent magnet materialtechnology, BLDC Motor power can be much large. So Two level inverter circuitwill not suitable for driving large power BLDC Motor.This paper aimed at using neutral point clamped three level inverter replace twolevel inverter to drive lager power BLDC Motor. Then according to three levelinverter topology analyse BLDC Motor control principle and PWM mode. Finally,according to the above theory made a three-level inverter drive BLDC Motorsimulation in Matlab. The simulation includes two cases: position sensor and withoutposition sensor, without position sensor control module is no longer using thedelayed30back-EMF method. This paper use line voltage difference shift90degrees method. Line voltage difference method advantage lie in its amplitude is2-4times the phase voltage. In this way BLDC Motor have a greater speed adjustmentrange. At the same time, this paper use three segment starting module to solve BLDCMotor without position sensor start-up problem. Three-stage startup method is rotorpre-position, rotor pre-accelerated and state switch. The simulation react three-levelinverter drive BLDC Motor actually situation. Simulation results and theoreticalanalysis is consistent. Finally, compared the speed, torque and current waveforms ofthree-level inverter drive BLDC Motor with two-level drive circuit. The three-levelcontrol system of BLDC Motor is proved more superiority.Finally, this paper use TMS320F28335digital signal processor of TI companyto design three-level inverter drive BLDC Motor controller hardware circuit andcomplete software debugging under CCS3.3environment. The practical operatingresults have verified the validity and feasibility of the three-level inverter driveBLDC Motor.