| In recent years,due to the scarcity of rare earth resources and energy shortages,replacing permanent magnet synchronous motors with permanent magnet motors has gradually become a trend in the market.Switched reluctance motor(SRM)drive system has attracted wide attention due to its simple structure,low manufacturing cost,high fault tolerance,flexible control,wide speed range,large starting torque and other advantages and has been applied in the field of home appliances and industry.As an indispensable part of the SRM drive system,the power converter plays a role in energy transmission and distribution.For the traditional SRM drive system,the asymmetric half-bridge converter is one of the most typical power converters.However,due to the need for two switches and diodes for each phase winding,it is large in size,high in cost,and has a single output level.Therefore,it cannot meet the needs of a wide speed range of the motor,thus affecting the performance of the SRM drive system.Researchers have proposed many new power converter topologies to meet the demand.In response to the above problems,this paper proposes a multi-level power converter topology with small capacitance.Compared with the traditional asymmetric half-bridge converter,it has the following advantages: First,it can be divided into two types according to the operating state of the SRM.Two working modes are low-voltage demagnetization mode and high-voltage demagnetization mode.The motor adopts low-voltage demagnetization mode when running at low speed,which can effectively reduce the conduction and turn-off losses of semiconductor devices,while the motor adopts high-voltage demagnetization mode when running at high speed,which provides a higher demagnetization voltage to ensure the rapid reduction of phase current Small,which is beneficial to broaden the speed range of the SRM and reduce the torque ripple.Secondly,the capacitor module is separated from the DC power supply as a power compensation unit,which can significantly reduce the volume and capacity of the capacitor under the premise of allowing a larger voltage ripple.Finally,by adding a filter inductor at the input of the power supply and adopting a power flow control strategy,the input current ripple is reduced and the selection range of the DC power supply voltage is also broadened,allowing the input voltage to be lower than the rated voltage of the SRM.In addition,a multiplexing method is adopted in the proposed power converter to significantly reduce the number of required semiconductor devices and the number of connections,which is very beneficial for reducing system cost,reducing volume and improving efficiency.This article first briefly introduces the working principle of the SRM.On this basis,the topology and working mode of the traditional asymmetric half-bridge converter are described,and the power generated by the SRM is analyzed.The influence of ripple on the input capacitance of a traditional asymmetric half-bridge converter.Secondly,a multilevel power converter topology with a small capacitance and a power flow control strategy is proposed for its existing problems.Its working mode,mathematical model,phase current rise and fall time,and dead zone pair are analyzed in detail.The influence of the DC bus voltage.By comparing with the traditional asymmetric half-bridge converter in terms of the number of devices used,average excitation and demagnetization voltage,etc.,its advantages are clarified.Finally,the feasibility of the proposed power converter is verified by building Simulink simulation model and RT-LAB experimental platform. |
