Research On Dual Power Solid State Switching Device And The Soft Switch Control Method

With the development of industrialization and power system, the demand of power supply’s reliability is getting higher, especially at large industrial enterprises, high and new technology industrial park, the key government departments and places where important loads operate. Two power supplies and related automatic switching device are needed to guarantee the reliability of power supply. As Power Electronic technology moves far forward, the solid state transfer switch based on power electronics components has more advantages against traditional mechanical switch on reliability and speed. Thus, it is necessary to research on dual power solid state switching device and soft switching of induction motor.Based on the parallel thyristor solid state switching device, this paper designs a main circuit structure and the hardware circuit of the controller. By setting up the induction motor mathematical model, stator’s current and electromagnetic torque under different transient are analysed. Stator’s current analytical expression of large inertia induction motor has been deduced with Laplace transform analytical method while the motor operates under constant speed. The determination method of two key control parameters which have the greatest impact on the transient impulse current of soft switch control has been studied. According to the requirements, this paper designs the software of solid state switching device. And the system utilizes the current and power as the auxiliary criterion to distinguish the fault location and that makes the device more practical and selectively.A simulation model in MATLAB has been built aimed to phase angle difference between the stator’s residual voltage and standby power. The comparison of inhibiting ability for the transient impulse current between direct switch control and soft switch control method has been done. The results verify the improved control strategy is accurate and effective.