Direct Torque Control Of Brushless DC Motor Without Flux Linkage Loop Operation In The Four-quadrant

The brushless DC motor (BLDCM) is derived from conventional DC motor, withelectronic commutation as replacement of mechanical commutation in DC motor. It isconsidered to be one of the most promising motor in this century. Motor machine oftenneed to operate in forward, reverse electric and braking four-quadrant in practiceapplication, such as aerospace systems, scientific instruments, transportations, nationaldefense and military equipments, Medical Devices, Industrial automations. However, inthe conventional direct torque control strategy, Motor four-quadrant operation needsimprovement on response speed and precision. So, a new switch state table aboutbrushless DC motor is deduced on the basis of the traditional switch state table in thisthesis, which makes brushless DC motor has a improvement on dynamic response andprecision at four-quadrant switch operation.With the development of industry，the work environment of electromotor haschanged a lot. The inner current control strategy in the traditional four-quadrant operationcannot meet the production needs. So, in this thesis, a new four-quadrant operation controlstrategy for brushless DC motor control system is proposed, based on the study ofhysteresis current control and traditional direct torque control.Firstly, this thesis describes four-quadrant operating principle of the brushless DCmotor, builds mathematical model of brushless DC motor control system, and describesthe method to select the appropriate voltage space vector for motor four-quadrantoperation. A new switch state lookup table with PWM modulation is deduced, inaccordance with the traditional switching lookup table.Secondly, programming simulation with MATLAB M-file simulates the motorforward、reverse electric and braking four-quadrant operation, and the result verifies thecorrectness and feasibility of the lookup table proposed.Finally, in order to further validate the correctness and feasibility of the controlalgorithm, experimental platform is built with DSP 28335 as the control core, includingthe software design to system. The motor forward、reverse electric operation is realized on the built experimental platform, and the experimental result shows the correctness andfeasibility of direct torque control without flux linkage loop for Brushless DC Motoroperating in the four-quadrant.