Mitsubishi Denki Kabushiki Kaisha

Susumu Jatsumura

Nobuo Sashida

Yushin Yamamoto

Takao Kawabata

Kazunori Sanada

Masatoshi Takeda

Masato Koyama

Masao Yano

Yoshihiko Yamamoto

Yuushin Yamamoto

Haruyoshi Mori

Susumu Matsumura

Yuuko Yamasaki

Koji Nishida

A power supply system of a high reliability and stability capable of suppressing a cross current flow by establishing rapidly synchronism between a power converter and an AC power source in a parallel operation for changing over the power supply sources. The power supply system comprises a current sensor for detecting an AC current supplied from a power converter, a comparator for making decision as to whether the AC current exceeds a predetermined value, and a regulation input means for fetching an active component of the AC power supplied from the power converter in response to an output signal of the comparator, wherein when the AC current exceeds a predetermined value, an output frequency of the power converter is speedily regulated so as to coincide with an output frequency of the AC power source in accordance with a drooping characteristic of the active component of the AC power, while in an isolated operation of the power converter, the output frequency is set at a predetermined value.

Electric power supply system using multiple power sources

A power conversion apparatus comprises an inverter circuit for converting DC power into AC power which has a first frequency; a transformer connected to the inverter circuit. A cyclo converter circuit having a bidirectional switch controls a direction in which an electric current passes and converts the output from the transformer into AC power which has a second frequency. A switching signal generating circuit generates a switching signal for controlling the polarity of the bidirectional switch of the cyclo converter circuit in such a manner that the output voltage from the inverter circuit does not encounter a short circuit.

Power conversion apparatus

Disclosed is a parallel power supply system including AC output inverters for controlling instantaneous values of output voltages by causing arms of respective inverters of the AC output inverters to effect switching in respective phases of the output voltages plural times during one cycle. A bus for connecting outputs on the inverters to a load so that a load current is shared by the inverters. A synchronous circuit for synchronizing the respective inverters by outputting common synchronous signals to the inverters. A detection circuit for detecting a cross current component of an electric current flowing between the respective inverters, and a control circuit for controlling the output voltages of the inverters to restrain the cross current component detected by the detection circuit.

Controlling system for parallel operation of AC output inverters with

An a.c. power supply apparatus, such as an uninterruptible power supply apparatus or a fuel cell power generation apparatus, has first, second and third converting devices connected in star configuration with a common bus, whereby the number of power converting devices is reduced and a compact, light weight and efficient power supply apparatus is realized.

A.C. power supply apparatus

A DC-to-AC electric power converting apparatus including an invertor circuit having a plurality of switching elements, a transformer connected to the invertor circuit, and a cyclo-converter circuit for converting the frequency of the output from the transformer. A carrier signal generator is provided for generating a carrier signal of a predetermined frequency. An invertor switching circuit for controlling the switching operation of a plurality of the switching elements of the invertor circuit in synchronization with the carrier signal and switching a plurality of the switching elements of the invertor circuit in a period in which an electric current is not substantially passed through the invertor circuit; a reference voltage signal generating circuit for generating a reference voltage signal for the AC voltage to be transmitted from the cyclo-converter circuit; and a switching signal generating circuit for generating a control signal for controlling the cyclo-converter circuit in response to the reference voltage signal generated by the reference voltage signal generating circuit and the carrier signal generated by the carrier signal generator.

DC to AC electric power converting apparatus

A 3-phase converter apparatus, in which a 3-phase A.C. power supply and a 3-phase converter operate in parallel on a common load BUS so as to share the load power, has an output voltage command generating device for generating an instantaneous command of the output voltage from the converter, and instantaneous voltage control device for controlling the converter so as to reduce the deviation of the instantaneous value of the output voltage of the converter from the instantaneous command generated by the output voltage command generating device. The converter includes at least one semiconductor switch for effecting a plurality of switching cycles in a half cycle of the A.C. power, so that the control of the phase of the output voltage of the converter with respect to the A.C. power supply is started at any moment.

3-Phase converter apparatus

An inverter apparatus having a reactor which suppresses ripple components contained in a charging current for a battery and is saturated when a current having a value larger than a predetermined value flows therethrough to have a very small inductance and allowing a small size and a low cost thereof to be designed.

AC-DC-AC apparatus having battery charging and discharging feature

Apparatus for correcting a DC component of an output voltage in an inverter, where correction is performed so that DC component contained in AC output voltage of an inverter main circuit is reduced. The apparatus is provided with a current detecting circuit constituted by, for example, a saturable reactor installed within an inverter control circuit to control operation of switching elements constituting the inverter main circuit and connected in parallel to the output terminal side of the inverter main circuit for detecting the current of the AC output of the inverter, and a polarity discrimination circuit for automatically discriminating both positive and negative polarities in the current at the output side of the inverter main circuit detected by the current detecting circuit and for generating a DC component correcting signal in the inverter control circuit. Only when a DC component is superposed to AC output and applied, the DC component is magnetically saturated at the DC side so that the DC component appearing on AC output of the inverter main circuit is corrected.

Apparatus for correcting DC component of output voltage in inverter

A static var compensator connected to a line node in a power transmission system and having a capacitor and a first reactor for producing and absorbing reactive power, respectively, and a second reactor connected between the line node and the common node of the first reactor and the capacitor for providing, in combination with the capacitor and the first reactor, a maximum leading reactive capacity so as to effectively reduce the capacities of the elements and for compensating for changes in reactive power resulting from a current fluctuation in response to a load fluctuation. The second reactor increases the reactive power produced by the capacitor when the reactive power absorbed by the first reactor is low and decreases the reactive power produced by the capacitor when the reactive power absorbed by the first reactor is high.

Static var compensators

A thyristor apparatus employing light-triggered thyristors comprises forward voltage detecting circuits (15) and a thyristor number detecting circuit (17). The forward voltage detecting circuits (15) detect forward voltages applied to light-triggered thyristors (13) to provide detected signals. The thyristor number detecting circuit (17) is responsive to the detected signals to cause light-triggered thyristors in a thyristor arm (U) to be turned on simultaneously in the case where the number of the light-triggered thyristors being supplied with forward voltages is one or more but not more than a predetermined number. Accordingly, if and when an overvoltage is applied to the thyristor arm (U), overvoltage suppressing elements (14) are prevented from being damaged even if partial commutation failure occurs in the light-triggered thyristors.

Thyristor apparatus employing light-triggered thyristors

An ignition equipment for light ignition thyristors for igniting a plurality of light ignition thyristors being connected in series with each other, which comprises an ignition circuit for generating a thyristor ignition electrical signal, a photoelectric conversion circuit receiving the thyristor ignition electrical signal to convert the same into a thyristor ignition light signal, a reverse voltage detecting means for detecting reverse voltage applied between an anode and cathode of each of the respective thyristors to transmit a reverse voltage detection signal, light guides for guiding the thyristor ignition light signal transmitted from the photoelectric conversion circuit to the thyristors, respectively, and light switches each inserted on the midway of each of the light guides and each interrupting the thyristor ignition light signal so as not to put the same into each of the thyristors while the reverse voltage is applied to each of the thyristors.

Growing community of inventors

Kobe, Japan

Nobuo Sashida