Yasutaka Kawata

Application of parallel connected NPC-PWM inverters with multilevel modulation for AC motor drive

The neutral point clamped (NPC)-PWM inverters have been put into practical use for large capacity AC motor drives, because of their many advantages. With the increase in use, still larger capacity inverters are also expected. In this paper, a parallel connected NPC-PWM inverter is applied for AC motor drive. The conventional modulation techniques are extended to improve the inverter characteristics. To determine an optimum modulation for controlling the parallel connected NPC-PWM inverter, various modulation techniques are devised and discussed, whose results are verified by experiment.

Novel modulation strategies of parallel connected NPC-PWM inverters for AC motor drives

The neutral point clamped (NPC)-PWM inverter has been put into practical use for large capacity AC motor drives, because of its various advantages. With the spread of applications, still larger capacity inverters are also expected. In this paper, a parallel connected NPC-PWM inverter is presented and conventional modulation techniques are extended to improve the inverter characteristics. For such waveforms, a frequency analysis approach is described, whose results are verified by experiments.

Simple and concise photovoltaic power generation system installed in veranda

The actual application of solar panels is almost installed on top of the roof of the detached house. However, some residents living in the apartment house are having a fairly strong desire to contribute for energy saving due to natural energy generation. In this paper, in order to give a reply, a simple and concise photovoltaic power conditioner installed in apartment house having verandas. Considering fairly reduced generation power and narrow space of installation, the system constructions should be simple and concise. In this paper, the circuit which gratified their wishes are presented and discussed.

Pursuit of simple PCS for photovoltaic power generation — Optimum waveforms

Utility-interactive photovoltaic power generations have been accepted and spread widely. Various innovative power conditioning systems have been also studied. In domestic utilization, the actual application of such solar panels is almost installed on top of the roof of the detached house. However, some residents living in the apartment house are having fairly strong desire to contribute for energy saving due to natural energy generation. The generating power in such case is fairly reduced, so the system construction should balance the reduced power. Thus, it is necessary to improve the construction toward simple one. In this paper, in order to give a reply, simple and concise power conditioners, especially inverter systems are devised and examined. Considering fairly reduced generation power and narrow space of installation, the system constructions should be compact. The circuit which gratifies their wishes are presented and discussed.

Pursuit of simple power conditioner for photovoltaic small power generation

Utility-interactive photovoltaic power generations have been accepted and spread widely. Various innovative power conditioning systems have been also studied. In domestic utilization, the actual application of such solar panels is almost installed on top of the roof of the detached house. However, some residents living in the apartment house are having fairly strong desire to contribute for energy saving due to natural energy generation. The generating power in such case is fairly small, so the system construction should balance such small power. Thus, it is necessary to improve the construction toward simple one. In this paper, in order to give a reply, simple and concise photovoltaic power generating systems are examined. With considering fairly reduced generated power, the system constructions including inverter should be compact. The circuit which gratifies their wishes are presented and discussed.

Asymmetrical modulation and over-modulation techniques of parallel connected NPC-PWM inverters for AC motor drives

A technique of parallel connection of power devices using current sharing reactors for neutral point clamped (NPC) PWM inverters is reported in this paper. The proposed modulation techniques can improve the output characteristics such as output voltage level or output harmonics. The output voltage waveforms of the proposed inverter have certain voltage levels during their half cycles, thus it is anticipated that it will be difficult to analyze the output waveforms. For such waveforms, a frequency analysis approach is described, whose results are verified by experiments.