Design And Analysis Of Improving Commutation On Low Voltage High Current Vehicle Generator

Modern armored vehicles widely adopted large number of electrical and electronicequipment,the generators often full load or overload running,which put forward higherrequirements to the running safety reliability of generator. In order to improvecommutation and decrease the level of spark for low-voltage high-current vehiclegenerators in the case of installation space is severely restricted,ensure the normal work ofthe electrical equipment and improve the power quality of generators, the asymmetric polestructure, non-uniform commutating pole,single wave windings playing a role of thepressure line and oblique brush etc are investigated for improving commutation.This paperresearched on the distribution of the flux line,the wave of the air gap magnetic field,andanalysis inner magnetic field under no loading conditions with the method of finite element.The results reveal that the magnetic field created by the special main poles,so it ensuresthe provision of suitable medium space for mechanical and electrical energy conversion.This article using the finite element method to analyze and calculate the generatorinner loading electromagnetic field distribution especially the air-gap magnetic fieldwaveform and characteristics as electromechanical energy conversion media,aimed atreducing the potential and improve the effect of commutation,it be refined analysis andpresentation of ommutating zone magnetic field and reverse current,to improve thequantitative basis for the commutation.The spark experiment also shows that thecommutation has been improved.this design scheme can improve commutation,decreasethe spark level,and inhibit the electromagnetic interference;it will help to improve thestability,reliability and security of the generator.The results can provide key technicalsupport to the development of low-voltage high-current vehicle generator.In order to further improve the power supply system reliability of low voltage highcurrent vehicle generator,hybrid excitation is used and the permanent magnets are addedbetween the main magnetic poles body and pole shoes.This paper researched on thedistribution of the flux line,the waveform of the air gap magnetic field,and analysis innermagnetic field at the loading by hybrid excitation and no loading by permanent magnet excitation alone respectively with the method of finite element.The results reveal that themagnetic field established by several excitation systems is still symmetric and uniformalthough the asymmetric structure,by comparing the permanent magnets excitation aloneand hybrid excitation in a generator magnetic field distribution and air gap magnetic fieldwaveform,the permanent magnet excitation and electricity excitation realized thesuperposition of magnetic field,and common establish main generator magnetic field.Hybrid excitation also reduces the current density of excitation coils and improves the heatdissipating performance compared with electrically excited alone.Through the performanceanalysis of the hybrid excitation,the output voltage waveform is very stable.The curve ofauxiliary excitation current along with velocity variation provide important basis forexcitation control devices and the development of control algorithm.