Research On Torque Control Technology Of Switched Reluctance Motor Based On Model Prediction

In recent decades,in order to reduce emissions and recede global warming,motor drive systems are increasingly used in a variety of industrial applications,such as electric cars,electric aircraft,wind turbines and so on.Switched reluctance motor(SRM)because of its advantages such as reliability,no permanent magnet rotor and low price,has already received extensive attention of the industry,and will become the future trend of development.However,SRM’s unique double-salient pole structure and complicated electromagnetic characteristic relationship lead to its large torque ripple,which is one of the main reason restricting its development.Direct torque control has many merits including simple structure and fast dynamic response.It has been widely used in all kinds of motor speed control system although double hysteresis control strategy has to maintain a high sampling frequency to achieve precision.At the same time this kind of control strategy ignores the SRM electromagnetic torque characteristic of complex.For the purpose of reduce torque ripple in SRM,model predictive control(MPC)has been effectively combined with DTC to achieve optimization control strategy.Direct Torque and Predictive Flux Control(DTPFC)is proposed in this subject.Based on the original flux data obtained from the experiments,the discrete nonlinear flux characteristic model of SRM is established in DTPFC scheme.The torque hysteresis loop in traditional DTC is retained to simplify the proposed algorithm and the weight factor in MPC algorithm is eliminated.Within a sampling period,the torque hysteresis loop selects three candidate voltage vectors for flux prediction,and then puts them successively into the evaluation function for further calculation,and selects the optimal voltage vector at the next moment for implementation.Through simulation analysis,the correctness and feasibility of DTPFC in torque ripple minimization are proved.In order to further restrain torque ripple,the range of basic voltage vectors was expanded from 6 to 12 based on the DTPFC algorithm.At the same time,according to the relationship of SRM electromagnetic characteristics,the selection rule of candidate voltage vectors was optimized,and only 4 candidate voltage vectors were increased per cycle.The improved control strategy has been compared with 12-voltage-vector DTC,and direct instantaneous torque control(DITC)with optimized turn-on angle.The simulated and experimental comparison and analysis are carried out under different operating conditions.Both simulated and experimental data show the feasibility and practicability of the proposed control strategy.