Research On Common-mode Voltage Suppression Strategy For Open-winding Electric Drive With Neutral Point Connected DC-Buses

With the rapid development of economy and society,people put forward higher requirements for energy conservation and emission reduction.Many countries in the world propose the idea of replacing traditional fuel vehicles by electric vehicles.Compared with the traditional fuel vehicles,the use and production of electric energy for electric vehicles are reduced.Overall pollution and the cost are relatively low.at the same time,electric vehicles is more convenient,which people are paying increasingly attentions to.Safety of electric vehicles is also increasing.In the research and development of electric vehicles,motor drive is the focus.Although today's motor drive technology has achieved large results,there are still some problems worthy for further study.Three phase asynchronous motor is widely used in electric vehicles,which has advantages of low cost,simple structure and high stability.In 1990 s,some scholars put forward the open winding motor drive topology.Compared with traditional topology,it has better fault tolerance and voltage output ability.This paper focuses on topology of open winding motor drive with neutrals connected,which combines the advantages of common DC bus open winding topology with isolated buses open winding topology.This topology is more ideal for solving the problem of high frequency voltage ripple between the two DC buses.Common mode voltage has a significant adverse effects for the motor drive system,which is manifested in high frequency common mode interference,bearing aging and zero sequence current.This paper focuses on suppressing the common mode voltage in the motor drive system and solving the problems caused by it.Based on the research of the modulation strategy and topology scheme of common mode voltage suppression,this paper proposes the motor drive topology of open-end winding motor drive with neutral connected and the topology scheme of double three-phase inverters motor drive with four bridge legs.With the corresponding modulation strategy,the common mode voltage in motor drive system can be suppressed and adverse effects can be reduced.In this paper,the common mode voltage suppression schemes are simulated and verified by creating simulation and experiment,which proves the feasibility of the proposed topology schemes.