Single-Stage Hybrid Energy Storage Integration in Electric Vehicles Using Vector Controlled Power Sharing

The dual inverter topology driving an open-winding motor is well known in high voltage motor drive applications. This structure allows two energy sources to be directly connected to an open-winding motor. This enables the integration of supercapacitors into a battery electric vehicle (EV). Unlike existing solutions, this article demonstrates dynamic power sharing between the dual energy sources by controlling the active and reactive voltages of the twin inverters, thus enabling the use of the supercapacitor for either active power assist and/or reactive power assist. The dedicated vector-controlled power sharing method and energy management is shown to achieve power sharing in the dual inverter drive integrating a battery and supercapacitor, thereby eliminating the need for an additional cascaded dc/dc converter to extract/supply energy to the supercapacitor. It also enables improved efficiency by eliminating switching losses in the supercapacitor inverter during low power operation. The proposed voltage vector splitting method is also shown to achieve battery-to-supercapacitor power exchange for regulating the net energy in the supercapacitor without affecting motor operation. A laboratory prototype utilizing a 110-kW liquid-cooled EV motor and supercapacitor bank is developed to verify the practical implementation of the power and energy management strategy.