Power flow management of a new hybrid cascaded multilevel inverter

Power electronic inverters are becoming more and more popular for various industrial drive applications. Many kinds of multilevel inverter topologies have been proposed to enhance the performance of motor drive system. In this paper, the power flow management for a new hybrid cascaded multilevel inverter is present. In this new hybrid inverter, the H-bridge inverter (main inverter) and the 3-level diode clamped inverter (conditioning inverter) are connected together to drive motor, but only the main inverter needs DC voltage source. The conditioning inverter just uses non-supplied ultra capacitors as its power source. Thanks to the proposed power flow management, the conditioning inverter can be used to store and reuse the braking energy of motor load. Therefore, compared with conventional H- bridge inverter, considerable energy efficiency improvement is achieved. Additionally, when the motor is at a steady speed, the conditioning inverter can provide the reactive power to the motor and improve the system dynamic performance. This control scheme has a wide range of practical applications, especially in the electric vehicle motor drive and marine propulsion system.