Based On Bus Clamping And Duty Ratio Of The Direct Torque Control Method Research

Direct Torque Control (DTC) is a new method for AC motor speed regulating sinceVector Control. It uses a double closed loop structure to control, the outer layer adpts speedclosed loop to output reference torque, the inner layer adopts hysteresis comparator andswitch vector table to control. Due to its structure and arithmetic is sample, low sensitivityto motor parameter, received wide attention of scholars and research institutions at homeand abroad.Although the advantages of direct torque control is obvious, but direct torque controlstill exists a series of problems cannot be ignored, the large torque ripple is one of the maindrawback of traditional direct torque control. Though the analysis of effect of the differentvoltage vector in different sectors to design a new switch vector table, in the new vectortable, the inverter keeps one-phase on or off in a sector, which makes the inverterswitching frequency and motor losses reduced, torque ripple is reduced Secondly, based onhysteresis comparator and only one voltage vector control in a sample period to presentbus-clamping based adaptation duty ratio control DTC strategy. Due to this strategy did notconsider the degree of the same voltage vector works in different speed area, finallypresented improved bus-clamping based discrete duty ratio control DTC strategy. Thisstrategy retains the advantages of bus-clamping and discrete duty ratio control, resulting inreducing torque ripple.In this paper, the proposed method is verified in MATLAB2010b/Simulinkenvironment, and the simulation results show that the proposed method effectively reducesthe torque ripple.