Hybrid Nine-Level Boost Inverter With Simplified Control and Reduced Active Devices

The single-phase hybrid nine-level boost inverter (H9LBI) with single input is presented to simplify the control and reduce the active devices. The proposed H9LBI includes only four complementary power transistor pairs to realize twofold voltage gain, requiring only four independent control signals from the controller. The voltages of the capacitors in the proposed topology can get inherent balance without auxiliary sensors or methods. The switched capacitors C₁ and C₂ of the proposed topology can naturally maintain at V_in; the floating capacitor C₃ inherently balances at 0.5 V_in. Therefore, the simplified control of the proposed topology is reflected in the greatly few independent control signals and the capacitors' inherent voltage balance without sensor or complex balancing algorithm. The mentioned features show its suitability for distributed generation applications. The operation principles are fully illustrated in this article. The inherent balance of the proposed topology has been deduced in detail. Moreover, the comparative assessment containing multiple nine-level inverters indicates the merits of the proposed H9LBI on fewer devices, simplified control, reduced total voltage stress, and lower power loss. The cost function (CF) is also used to evaluate different multilevel inverters in a comprehensive way. The result of CF shows that the proposed H9LBI has the advantage of reduced overall cost for design. Finally, the simulation and experimental prototype are implemented to verify the steady and transient performance of the proposed topology.