Research On Generation Mechanism And Reduction Strategy Of Vibration In Electric Vehicle Used Switched Reluctance Motor

As a new kind of vehicle,electric car has the advantage of low energy consumption and small environment pollution.Thus it can effectively solve the large energy consumption and pollution problems raised by transportation.As one of the key techniques in electric vehicle,the performance of electric motor and its drive system will directly affect the overall performance of the vehicle.Switched reluctance motor(SRM)has raised concerned by academy community and industries since it appeared.Permenant magnetic synchronous motor(PMSM)is widely accepted which has the best performance.Compared with PMSM,SRM has no obvious difference in the aspects of highest efficiency,width of efficiency platform,power density and so on.And the efficiency and speed regulation performance of SRM are even better than PMSM when at high speed region.However,due to the doubly salient characteristic,the current excitation of SRM in non-continous,which will cause the vibration and noise obviously larger than PMSM.The terrible customer experience limits the promotion of SRM in many industries which focuses comfort.However,as SRM does not need permanent magnetic material,which can not be regenerated.And as the material is easy to demagnetize under high temperature,SRM should has more space to develop and is suitable for more applications.Thus the research of vibration mechanism and vibration reduction strategy in electriv vehicle SRM has significance academic meaning and application value.This paper will investigate the mechanism of vibration and its reduction strategy in SRM.Firstly,the relation between vibration and electric parameters will be analyzed qualitatively.Based on the relation,a basic acceleration model will be established.Afterwards,the relation will further be described by accurate math equations,thus to establish a fast acceleration computation model.Based on the vibration model,the relation between vibration harmonics and current harmonics will be analyzed.And the influence of switch angles on current harmonics and vibration harmonics will be analyzed.Thus the vibration reduction method based on switch angle optimization can be proposed.Finally,a vibration reduction method based on frequency disturbance theory is proposed to further reduce vibration.The main innovations of this paper is as follows:1.A vibration modeling method based on Least Square Support Vector Machine(LSSVM)and modal superposition is proposed.Based on detailed analysis of original data,the physical cause and mechanism of vibration impulse and resonant frequency natural oscillation are innovatively proposed.Based on data,LSSVM and modal superposition method are used.And a highly accurate vibration model is proposed based on time and frequency domain combined method.The model can accurately predict the value of acceleration,whose error between predicted value and measured value is less than 10%.2.A fast vibration calculation method based on analytical method is proposed.Firsy,the origin of vibration is analyzed from the perpective of radial force change.And the relation between acceleration and electric parameters,especially current slope,is accurately expressed.Based on that,a fast acceleration computation method based on analytical calculation is innovatively realized.Compared with traditional complex analytical methods and artificial intelligent methods,the simulation time can be reduced from second level or even hour level to millisecond level.3.A vibration reduction method based on Optimal Switch Angle Selection is proposed.The radial force is regarded as medium innovatively.Firstly,the relation between radial force harmonic and vibration harmonic is investigated.Then the accurate math expression between radial force harmonic and current harmonic is deduced.Thus the relation between current harmonic and vibration harmonic can be deduced indirectly by radial force.After that,the analytical relation between current harmonic and switch angle is deduced.Thus the current harmonic can be reduced by regulating contron paremeters,mainly by switch angle optimization.As a result vibration harmonic can be reduced.This method is easy to implement.And the vibration can be reduced by 76.2% at dominant frequencies.4.The vibration reduction method of randomizing turn-on angle based on frequency disturbance theory is proposed.The sigal disturbance theory in communication field is innovatively adapted into the research.Based on frequency disturbance techniques,the multiple frequency reduction method is proposed,which widens the effective application range of the reduction method.It can reduce vibration from all frequencies,especially the ear sensitive frequency range of 1kHz~3kHz.The main frequencies can be reduced by 50%.And other frequencies can be reduce by more than 90%.