Research And Design Of A Novel Power Converter For Switched Reluctance Motor Torque Ripple Suppression

The switched reluctance motor drive systems have the characteristics of wide speed range, high reliability, low cost, simple maintenance, which makes SRM widely applied in social production. Because of the SRM doubly salient structure, its torque ripple is obvious, which seriously affectes the application in extreme occasions. In order to solve this problem, a novel active boost converter with simple structure and real-time control of demagnetization voltage is proposed, combining with direct instantaneous torque control to suppress the torque ripple in this paper. The main studies include the following aspects:First of all: the development and application of SRM drive system are introduced. The typical main power topologies of fast excitation and demagnetization are discussed. According to the basic electromagnetic relationship, linear model of the SRM is derived. The reasons of torque ripple are analyzed and the common control strategies of torque ripple suppression are compared in the paper.Secondly: the operating principle of typical active boost converter and four-level converter are analyzed. On the basis of them, a novel active boost power converter is proposed. The detailed theory of the proposed converter is analyzed combing with the direct instantaneous torque control strategy.The relationship between demagnetization voltage and rotor position, working current is derived. The calculation formula of the key device in circuit is given.Thirdly: the hardware and software of the drive system are designed. The main power circuit, power supply circuit, position detection circuit, drive circuit, voltage and current detecting circuit, protection circuit are included in hardware. The module initialization subroutine, position signal read and speed calculation subroutine, speed closed-loop subroutine, torque hysteresis subroutine, DA conversion subroutine are all included in software.Then: the simulation model of drive system based on asymmetrical half-bridge converter and the novel active boost converter are built by PSIM software. The validity of the proposed converter and control strategy is proved through the comparing results of simulation.Finally: The experimental results are acquired through the experiments of rated speed, rated torque, speed abrupt change and torque abrupt change. The superiority of the novel active boost converter of reducing the torque ripple and increasing the motor output efficiency under the condition of speed and load change large are verified by the experiments.