Introduction The electro-magnetic generator commonly used in automobiles generally has high excitation loss leading to low efficiency. And it cannot effectively provide power for the vehicle, thus shortening battery life.In order to solve the issues, a parallel double-rotor hybrid excitation generator is proposed, consisting of a radial permanent magnet rotor and a claw-pole electro-magnetic rotor that share the same stator core. Methods Using the equivalent magnetic circuit method, the magnetic circuit models of the generator are established, and the computational formula of synthetic permeance, synthetic leakage permeance, effective flux, and leakage flux are derived. Taking advantage of the theory of a permanent magnet motor and electro-magnetic generator, the structural parameters are designed. Furthermore, a finite element model is established according to the structural parameters, the permanent magnet field is analyzed, and the parameters of the stator slots and claw poles are optimized according to the results of magnetic field analysis. Moreover, the mechanism of magnetic field synthesis and adjustment are verified. The influences of the claw-pole parameter on the output voltage waveform and air-gap flux density are analyzed, and the optimum value claw tip’s pole-arc coefficient is determined. Using the equivalent magnetic circuit and finite element methods, the magnetic flux density of the yoke of the permanent magnet rotor, the root of the paw-pole, and the flange and the excitation winding bracket are calculated. Results The influence of exciting current on noload terminal voltage is further analyzed, demonstrating that the hybrid excitation generators have excellent voltage adjustment characteristics. It is verifying that the field-and-circuit method can improve the accuracy of electromagnetic analysis. Using the design and analysis results, the prototype is trial-produced. The voltage regulation characteristics, no-load characteristics, and external characteristics are obtained. The test results show that the novel hybrid excitation generator performs well. Discussion The method can be applied to the development of hybrid excitation generators for automobiles. However, the stability and environmental adaptability of the hybrid excitation generator need to be further studied to speed up its popularization and application.
Ma et al. (Wed,) studied this question.