Power electronics layout in a hybrid electric or electric vehicle drive system

The power electronics in a drive system of a hybrid electric or electric car can be subdivided in different function blocks without considering the effective concept of the drive system (series/parallel hybrid, range extender) or the kind of electrical machine in use (direct/alternating current machines). This paper identifies the main function blocks and discusses the requirements and possible solutions. Some of the solutions were implemented in the Hybrid III, the electric hybrid vehicle project of the Swiss Federal Institute of Technology. Two function blocks, a battery charger concept, using power factor control and capacity compensation, and a DC-link braking resistor with low ripple current are presented in detail. The battery charger has low current harmonics, high charging efficiency and an increased usable battery capacity. The DC-link braking resistor reduces the DC-link ripple current and therefore reduces the amount of filter and DC-link capacitors.