Optimization of AC–DC Converters for Regenerative Train Suspensions

This article focuses on the dynamic optimization of the operating conditions of two types of ac–dc converters, a diode bridge rectifier and a full bridge active rectifier, which are used for interfacing regenerative rail vehicle suspensions based on ac electromagnetic generators. A theoretical analysis shows that, for both types of converters, the optimal operating conditions, leading to the maximization of the extracted power, can be predicted from the measurement of the generator speed. In particular, as regards the diode bridge rectifier, it is shown that the optimal value of the dc side voltage is related to the generator speed. As regards the active full-bridge rectifier, it is shown that a relationship exists between the optimal converter duty cycle and the generator speed. Experimental results validate the proposed theoretical models both in case of ideal constant generator speeds, and in case of more realistic time-variable generator speeds. The proposed analysis enables the design of high-performance speed-driven maximum power point tracking techniques for regenerative vehicle suspensions.