Takayuki Suzuki

TL;DR: In this article, a new configuration for a neutral point clamped PWM inverter and its control strategy is proposed, which consists of an auxiliary circuit with four switching devices and a single full-bridge inverter.

TL;DR: In this article, a hill-climbing control method with which it is possible to extract wind energy effectively, even when the system characteristic is unknown, is suggested, with the objective of following the quasi-maximum output only by measurements of the load terminal voltage and current, which are relatively simple to measure with high accuracy.

TL;DR: In this article, a new PWM method for neutral-point-clamped (NPC) inverters is introduced, which is based on closed-loop control of the line-to-line voltage vectors.

TL;DR: A novel multi-step PWM inverter for a solar power generation system that has many features such as good output waveform, small size of filter, low switching losses, and low acoustic noise is presented.

Abstract: Several PWM techniques for three-level inverters have been introduced. However, multilevel inverters with more voltage levels have not been considered yet. The paper proposes a PWM control method for four-level inverters. The four-level inverter uses six power switches per leg, but the blocking voltage of each switch is equal to one third of the DC-link voltage. The control method is based on closed loop regulation of the line to line voltages. It uses independent hysteresis comparator controllers to regulate the direct and quadrature axis components of the three-phase output voltages. The vector selection is adjusted according to the input reference to improve the voltage generation. The DC capacitor voltage balance is considered, and a method to control the variations is introduced. Computer simulations and the result of an experiment are given to confirm the validity of the proposed control scheme.