High-Speed Range Enhancement Of Switched Reluctance Motor With Current Continuous Conduction Mode

Switched reluctance motor (SRM), as a new mechatronical motor, has the advantages of simple rugged, wide speed range, high efficiency, excellent high-speed performance, etc, is very suitable for electric vehicles applications, especially high-speed drive applications. But, because of the doubly salient structure and serious non-linear magnetic, SRM has very complex electromagnetic properties. Additional, the switching angle is also needed to be regulated at high-speed range, so it makes it harder to control the high-speed operation of SRM.Current amplitude control of SRM is ineffective when running at high speed range, and angular position control method is commonly used. But due to the highly nonlinear characteristics, the relation between the switching angles and the motor output is very elusive, so the control parameters are difficult to determine. Apart from this, SRM shows weak magnetic characteristics when running at natural characteristics area, torque and power output capacity decrease seriously. To solve these two main problems, this paper researches the high-speed operation of SRM in depth. The article can be divided into several parts:Firstly, to deal with the problems of high magnetic saturation and severe non-linear characteristics of SRM, we take the way of non-linear function fitting and Fourier series approximation to obtain the flux characteristics analytical formula of SRM, and further derive the calculation formula of electromagnetic torque as a function of stator current and rotor position. Thereby, we establish a fairly accurate nonlinear mathematical model for SRM.Then, this paper focuses on the constant power operation and angular position control method of SRM. In the basis of analysis of the impact of turn on angle and turn off angle on motor running, we solved the switching angle optimization rule by trial and error method. And, we build an angular position control simulation system base on this optimization rule and achieve the constant power characteristic of SRM above base speed.Finally, to enhance the output capacity of SRM at natural characteristics area, this article breaks the traditional discontinuous conduction mode of SRM and introduces a new current continuous conduction mode innovatively. Then we establish the control system of two commonly used control schemes, and demonstrate the effectiveness of current continuous conduction mode by simulation.