Low voltage and high power DC-AC inverter topologies for electric vehicles

In electric vehicles, systems with distributed low voltage batteries and DC bus voltage below 60 V could be an alternative to systems with a single high voltage battery. In this work, different low voltage DC-AC inverter topologies are investigated and compared in terms of power losses and component requirements. For a given driving cycle of an electric vehicle the operating points and the required size of the system components are calculated by using an iterative method. This will be used to estimate and to compare the motor losses (by using a characteristic map of the motor) and the DC-AC inverter losses (based on a loss and thermal model of the switches) for each inverter topology. Finally, the simulation is performed and the results are compared with each other. It turns out that the system with a bidirectional DC-DC converter with controlled DC-link voltage inverter has the best performance.