A variable voltage converter with direct bypass for traction drive inverters

In this work, an innovative and feasible solution is proposed for a Variable Voltage Converter (VVC) with direct bypass for traction drive inverters in HEVs. With the proposed method, the VVC capability is significantly increased and power loss is dramatically reduced. The advantages associated with this method include 1) Mitigation of VVC oscillation issues occurring during fast power flow transients, since the VVC output minimum voltage is directly clamped to the HV battery voltage anytime the output side voltage is lower than that of the HV battery voltage. 2) A significant increase in VVC pass-through operation capability; as a result, both vehicle EV drive maximum speed and duration are increased, 3) significantly reduced VVC power loss and noticeably increased vehicle fuel economy. This solution has been proved to be very useful and feasible especially for Plug-in HEV applications.