Mitsubishi Denki Kabushiki Kaisha

Takeaki Asaeda

Yoshihiro Yamaguchi

Masahiko Akamatsu

Katsumi Satoh

Shinzo Tamai

Hiroshi Masunaga

Noritoshi Hirano

Tomohiko Aritsuka

Fuminori Nakamura

Shotaro Murakami

Takashi Yutani

Toru Nakamura

In a gate control device for four self-arc extinction elements connected in series and two self-arc extinction elements connected in reverse parallel between the respective terminals of clamp diodes, individually, there is provided a PWM circuit that generates conduction control commands, and a gate control circuit including a delay circuit group that generates gate signals with respect to the respective self-arc extinction elements on the basis of respective conduction control commands. A pair of the self-arc extinction elements are rendered conductive at the same time, and another pair of the self-arc extinction elements are rendered conductive at the same time.

Three-level inverter controller reducing commutation loop inductance

The current-limiting device includes a silicon substrate having surfaces opposite to each other, and two electrodes deposited respectively on the opposite surfaces of the silicon substrate. The silicon substrate is of a three-layered structure including an N&minus; layer of a low impurity density and an N&plus; layers of a high impurity density formed respectively on opposite surfaces of the N&minus; layer . The electrodes , are deposited on an outer surface of each of the N&plus; layers remote from the N&minus; layer . The constant current substantially flows in the current-limiting device if the applied voltage is higher than a predetermined value.

Current-limiting device

A voltage source type power converting apparatus having voltage source type power converter units and phase-shifting transformers. The transformers have either a common multiple-phase primary winding or a group of parallel connected multiple-phase primary windings, either of which being connected in parallel or series to a multiple-phase AC system. The transformer further include a group of multiple-phase secondary windings with phase differences with respect to each other and which are connected to voltage source type power converter units. The voltage source type power converter units are operated with the phase differences. Accordingly, the construction of the multiplexing phase-shifting transformer is simple, and fundamental electric variables can be controlled by a simple phase controlling operation. In addition, a higher harmonic defect of the AC system can be reduced, and the DC voltage can be easily raised.

Voltage source type power converting apparatus

A control device for an active filter according to the present invention comprises a ROM circuit for producing output signals sin .theta. and cos .theta. from a phase signal generated from a PLL circuit, a first multiplier for multiplying a load current detection signal by the output signals sin .theta. and cos .theta., a sample-holding circuit for integrating the output signal of the first multiplier and holding the integrated value to produce peak values of valid current component and invalid current component for constituting the basic wave component of the load current, a second multiplier for multiplying the peak values by the output signals sin .theta. and cos .theta., and a PWM control circuit for PWM-controlling the input current of the active filter with a harmonic current signal obtained as the difference between a basic wave current signal of the load current during a period of next one period of the single-phase a.c. power source and the load current detection signal by utlizing as the basic wave current signal of the load current of the period of next one period of the single-phase a.c. power source the basic wave current signal obtained by combining the valid current component and the invalid current component of the basic wave component outputted from the second multiplier.

Control device for active filter

An inverter comprises a pair of reactors connected in series between a positive arm element and a negative arm element, snubbers each connected in parallel to respective arm elements, and a feedback circuit for transferring electrical energy stored in the snubbers back to the d.c. power source. The feedback circuit includes a self turn-off switching device which is controlled to become conductive during a certain period in correspondence to the on-off operation of the arm elements so that energy stored in the snubbers is fed back to the d.c. power source through a current transformer and a rectifying circuit during the on-state of the device.

Growing community of inventors

Tokyo, Japan

Takeaki Asaeda