Research On Novel Direct Torque Control Of Induction Motor

In the AC driving technique, Direct torque control (DTC) technology, which is characterized by the rapid response of torque and flux, has been widely attention. In recent years, aimed at the problem of DTC technology, many improved methods are proposed by scholar at Home and Abroad. In this thesis, a novel DTC scheme which not only remains the good performance but also eliminates the disadvantages is presented.The novel scheme is the method which is based on estimation model of the stator flux, constant switching frequency and space vector modulation. There only exist two PI regulators in the system, which eliminates the difficulties of multi-regulators without calling for complex control algorithms.It brings about lots of problem to use the pure integral in the voltage model. After making deep analysis on the traditional stator flux linkage observer models, an ideal improved algorithm is introduced.Speed senseless control is a focal point of research, but the speed identification is relied on the motor parameter. The off-line identification method of motor parameter, which is used of the frequency domain analysis, strong currency, small computational amount and easy to realize, is proposed in the thesis.The direct torque control system has more serious Dead-time Effect in the low-frequency, A compensation strategy for Dead-time effect is one of the present research focus. In this paper, Dead-time compensation method aimed at SVPWM modulation method is simple, easy to realize.In general case, the simulation system uses existing modules of the Matlab/Simulink, the modules are packed with bad visibility, and not real-time change of the parameters, so a direct torque control system model is built on the S-Function, which consist of lots of modules and provide convenience for the comparison of a variety of direct torque, the off-line identification of motor parameters and dead-time compensation algorithm and so on.All the simulation tests are completed in this Simulink system, which verify the effectiveness and feasibility of the algorithm and provides a theoretical basis for the experiment.Finally, the experiments are completed in TMS320f2812 control platform. The novel direct torque control, parameter identification and the dead-time compensation are verified by this test platform. These tests establish foundation for product forming of the direct torque in the future and have great practical value.