The relationship between output power and accumulated energy of the unbalanced input voltage three level inverter with the EDLC

In AC motor drive systems, the motor input voltage is limited by the maximum inverter output voltage, which restricts the motor performance. As one of the solutions, an unbalanced input voltage three level inverter can be applied to boost up the input voltage by means of energy storage devices, such as EDLCs. Applying EDLCs as energy storage devices, energy management is required through the whole operation of the motor because the energy density of EDLCs is not so high. In this paper, a method of energy management for EDLC and a method to determine the capacity of EDLC are revealed when the load profile are given with the inertial load.