Single Phase Diode-clamped 3-level Half Bridge Inverter With Half Cycle Mode Control

Since 1990s, multilevel power converters are becoming a preferable solution in the large power application for these following advantages: more sinusoidal output voltage, lower voltage stress, and lower EMI.Among these multilevel topologies, diode-clamped multilevel converter is more widely used for its simpler fabrication and higher reliability. Some inverters applying diode-clamped 3-level topology have been used in industry application. Many popular control strategies such as SPWM, Hysteresis control and SVPWM could be used directly in this converter, in which the dead time is needed to prevent the shoot-through problem and the dead-time effect is introduced. In this work, a new control scheme named Half Cycle Mode (HCM) control is studied. The HCM control is applied in a single phase Diode-Clamped 3-Level Half Bridge Inverter (DCTLHBI) with no dead time added.In the dissertation, operation principle of single phase DCTLHBI applying HCM control is analyzed in detail. In the control strategy, upper and lower bridge-arm switches are controlled in the positive and negative half cycle of output current respectively .Considering that no dead time is added, output voltage performance will increase. The performance of HCM in DCTLHBI is studied based on SPWM and hysteresis control respectively, and the operation of the no dead-time strategy is described. Simulation and experimental results confirms the validity of the analysis and feasibility of the control strategy. Moreover, simulation results of series/parallel DCTLHBI and diode-clamped 3-level full bridge inverter (DCTLFBI) applying HCM control strategy is given.At last, based on the modeling of single phase DCTLHBI applying SPWM control strategy, the design method of its dual-loop control and LC filter is given.