The Research On Electromagnetic And Built-in Radial Permanent Magnet Combined Magnetic Pole Stabilized Generator For Vehicles

Hybrid excitation generator not only has the advantages of high efficiency,high power density and high reliability of the permanent magnet generator,but also has a good voltage adjustment characteristic of the electric excitation generator.It can effectively solve the difficult problem that the output voltage of the generator is difficult to be stable because of the change of the load and speed caused by the changeable driving condition of the vehicle.So it has become the main development direction of vehicle generator.By analyzing and comparing the different structures of the hybrid excitation generator,a new hybrid excitation generator with a suspended brushless claw pole electromagnetic rotor and built-in radial permanent magnet combined magnetic pole rotor is proposed.In this new structure,the two rotors share one armature winding,the brushless electromagnetic rotor has no additional air gap,so the excitation efficiency is high,and the flux of each pole of permanent magnet rotor is provided by many permanent magnets,so the effect of magnetic agglomeration is remarkable.The equivalent magnetic circuit model of permanent magnetic field,electric magnetic field and synthetic magnetic field are established by using the equivalent magnetic circuit method.The magnetic flux,leakage magnetic flux,magnetic conductance,leakage magnetic conductance and no-load leakage coefficient of three magnetic fields are calculated,on this basis,the magnetic circuit structure is analyzed,and the measures to reduce magnetic flux leakage and enhance magnetic field strength are put forward.The finite element analysis models of the three magnetic fields are established by the finite element software.The simulation results show that the magnetic field of the hybrid excitation generator is uniform and the simulation magnetic circuit is the same as the equivalent magnetic path analysis;the maximum flux density of electric magnetic field is 1.8T,this shows that the magnetic field is unsaturated,the permanent magnetic field is saturated in the magnetic leakage region,which can help to reduce the magnetic leakage coefficient.the field solver is used to solve the main magnetic flux and leakage flux respectively,the calculated magnetic flux leakage coefficient of the synthetic magnetic field is 1.24,which is basically the same as that of the equivalent magnetic circuit method,so the equivalent magnetic circuit method has a higher calculation precision.The analytic expressions of the harmonic induction electromotive force along the circumferential distribution of the permanent magnetic field and the electric magnetic field are deduced by using the numerical analysis method,the main influence parameters and the influence rule of each parameter on the high-order harmonics of magnetic field induced no-load electromotive force are analyzed to select the optimum structural parameters.The simulation model of the hybrid excitation generator is established by using the optimal parameters,the no-load characteristic and output characteristic of the generator are analyzed,after optimization,the no-load induction electromotive force curve is smooth,the harmonic content is less,and the sinusoidal distortion rate of generator line voltage is low,so as to meet the relevant standards.Changing the magnitude and direction of the electric current can change the magnitude of the no-load induction electromotive force,and achieve the enhancement and weakening effect of electric magnetic field.The generator can output sinusoidal voltage well in a certain load range and have good voltage stability.