Direct Instantaneous Torque Control System Research Of Switched Reluctance Motor

With the development of power electronics,computer control and microprocessor technology,switched reluctance motor drive(SRD)aroused wide attention of experts and scholars both domestic and abroad gradually.Switched reluctance motor(SRM)not only has many advantages such as simple structure,low cost and flexible operation and wide speed range,but also can realize the quick start and run forward and reverse frequently under the very small current,reaching the performance indexes of high precision and high output.However,because of the special doubly-salient pole structure and switching power supply mode,the large torque ripple becomes its inherent defect.It not only causes the noise,but also leads to greater speed fluctuations.Although the traditional control can perform well in speed,the torque ripple remains in considerable amplitude.Aiming at the high torque ripple of SRM,the direct instantaneous torque control(DITC)scheme is presented in the paper.Firstly,the fundamental structure and operation principle of SRM are introduced,and then the mathematical models are proposed in this paper.As the traditional control methods,the chopped current control(CCC),chopped voltage control(CVC)and angle position control(APC)are analyzed.With analyzing the causes of torque ripple,some popular approaches to decrease torque ripple and the theory of DITC method are introduced.After the deep analysis of DITC method,three kinds of torque controller are presented,respectively,the double hysteresis loops,torque difference controller and advanced torque difference controller.The PI speed controller which containing the elimination term is used in the closed-loop speed control.It can avoid the shock and overshoot during the period in starting or sudden increase load.The feedback torque is estimated by current and rotor position angle through the bilinear interpolation algorithm on the basis of the numerical relationship table which established between the three values of the torque,current and rotor position.The control simulation model for the four-phase 8/6 SRM is built up in Matlab/Simulink environment with detailed analysis of every component module.According to the simulation results by experiments which three kinds of torque controller are used respectively,the validity of the method is demonstrated.On the basis of theoretical analysis,combined with simulation model and experimental results,the test platform is established,whose drive unit is a 370 W four-phase 8/6 SRM and take the TMS320F2812 PGFA as the main control chip.The operating principle of the hardware circuit together with the flow charts and function of the software program are introduced and analyzed comprehensive and clearly.The hardware circuit mainly includes rectifier circuit,power conversion circuit,current sampling circuit and optocoupler and trigger circuit.The software algorithm design consists of the DSP control program and the Lab VIEW operation interface.At last,the experiment results of the platform confirm that the strategy of DITC is effective in reducing the torque ripple.