Direct Torque Control System Research Of SRM Based On Backstepping Adaptive Theory

Switched reluctance motor(SRM) has advantages of reliable, simple structure, low cost, and good fault-tolerant capability. It has attracted so much attention in recent years. However, due to the inherent doubly salient motor structure and nonlinear characteristics of flux-linkage which generate large torque ripple when motor operates. This reduces the stability of the SRM control and severely limits its application in the fields which need high control precision. So, how to effectively reduce the motor torque ripple gradually becomes the research hotspot for scholars in the world. In view of the problem above, a direct torque control(DTC) system of SRM based on backstepping adaptive theory is proposed in this paper. The stability of the DTC system is guaranteed through lyapunov function. The designed torque controller can not only convergences to stable condition, but also reduces torque error effectively.This paper briefly illustrates the research status of DTC technology. It also illustrates the motor working principle, mathematical equations and three models of SRM. After this, it introduces the control policies and power circuit of motor.A instantaneous online torque calculation method is proposed and this mainly contains three parts—flux-linkage test of SRM, estimation of magnetism co-energy and instantaneous torque estimation. In the part of flux-linkage test, according to the flux-linkage estimation error through analysis, a method is proposed in order to calibrate the equivalent resistance when SRM operates at static or low-speed condition, and this method can revise estimation error. These all have been down through the experiment platform.The direct torque control strategy of SRM based on backstepping adaptive theory is analyzed. The stability of the designed torque controller is determined by stability criterion of lyapunov function. The controller are accomplished through both ideal linear model and nonlinear model.In order to decrease the difficulty of controller design, increase feasibility of the strategy and guarantee control precision, the torque controller is accomplished through ideal linear model of SRM. This method is compared with traditional fuzzy DTC control strategy through MATLAB simulation. Dynamic follow performance of the controller and convergence process of the system are deeply analyzed too.The hardware and software design of control system are introduced. The chopped voltage control(CVC) and motor operation test are finished on the experiment platform. The experimental results show that the DTC strategy proposed can effectively reduce torque ripple and follow the torque change rapidly. It achieves high performance control of the SRM and has practicability and reference value.