Study of the development of DC-DC converter for electric bus

This paper is to develop a DC-DC converter which can convert high battery voltage into low DC voltage supplied to the electric system of the eco-friendly electric bus. As the electric bus parts have large capacity and the larger difference between input and output voltages comparing to those of the passenger cars, high capacity power converter is required. In order to implement the circuit, we have applied full-bridge converter topology. In order to achieve the high efficiency, we have also performed control with zero voltage switching using phase shifted method. Moreover, we could implement a converter that has characteristics including high output density, high performance, small size and lightweight through optimal design of high frequency switching, transformer and inductor. We fabricated a prototype to satisfy design specifications and could achieve objectives of small size and lightweight from test results of 40kg in weight and 22.95 liters in volume. Especially, we achieved high efficiency of 91%.