Controlled Rectification Method For Automotive Hybrid Excitation Brushless DC Generator

With features of low cost, remarkable effect in energy saving and emission reduction, belt driven integrated starter generator(BSG) system with ultracapacitors is potential for automotive use. With the performance of compact, high efficiency and easy control and so on, hybrid excitation brushless DC machine(HE-BLDCM) is suitable for BSG use. The paper draws attention to generating performance of HE-BLDCM type BSG system, where HE-BLDCM can be seen as hybrid excitation brushless DC generator(HE-BLDCG).Two points are focused in the paper. Firstly, to decrease the amount of permanent magnet(PM) used in HE-BLDCM generating capacity at low speed should be promoted, which will reduce the system’s cost and difficulties in flux-weakening at high speed. Secondly, DC-link voltage recovery speed should be improved to meet requirements of increasing automotive sensitive device.Firstly, HE-BLDCG controlled rectification system structure and the control method are introduced. The sysem winding current in continuous conduction mode(CCM) and discontinuous conduction mode(DCM) and critical condition of both modes are analyzed. Power, efficiency and generating capacity of system in CCM are debated. The capability of boosting DC-link voltage of the system and improving generating capacity at low speed is theoretical proved.Then, DC-link voltage recovery theory of HE-BLDCG controlled rectification system is analyzed. DC-link voltage recovery time calculation formular is deducted, and calculation results indicate that controlled rectification system can improve DC-link voltage recovery speed.What’s more, steady state performance of HE-BLDCG controlled rectification system is simulated. Structure is introduced. Logic, fuction and performance of the system are simulated, and the results are analyzed.Finally, Hardware and software structure of HE-BLDCG controlled rectification system are introduced. Diode rectification and controlled rectification experiments are finished. The results verify the controlled system’s validity of improving generating capacity at low speed and DC-link voltage recovery speed.