A Dual-Active-Bridge Converter for Novel Trolleybus Powertrain System

Traditional trolleybus has several shortcomings which cannot meet today's needs. No off-line operation capability and double insulation design incompatible with present wide-spread normal electric buses are most concerned ones. Dual mode operation with diesel engine had solved the off-line operation issue whereas its zero emission image was spoiled. Equipping batteries and later in-motion-charging have in the past 27 or so years totally solved the off-line operation issue and serviced the market rather well. In this paper, a novel trolleybus powertrain system based on isolated in-motion-charging battery-charger is introduced to explain how the double insulation issue is further solved. Three such kinds of isolated battery-chargers are now available in Chinese market. The one based on dual active bridge topology is presented in great detail. It is expected that the trolleybus equipped with such a new powertrain system will accelerate its revival in the public transportation sector.