MERSTech Co.

Tokyo, Japan

MERSTech Co.

Tokyo, Japan
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Isobe T.,University of Tsukuba | Shiojima D.,Tokyo Institute of Technology | Kato K.,MERSTech Co. | Hernandez Y.R.R.,MERSTech Co. | Shimada R.,Tokyo Institute of Technology
IEEE Transactions on Power Electronics | Year: 2016

This paper discusses reactive power compensators from the point of stored energy in the capacitor, and proposes a single-phase full-bridge configuration of semiconductor switches to be used with reduced equipped capacitance for reactive power compensation. By applying this concept to shunt-type static var compensator, a static synchronous compensator can be achieved with reduced-sized capacitor. Additionally, the switching loss can be reduced due to its distinctive capacitor voltage waveform, which swings at the double of the line frequency. Modulation technique and capacitor voltage control method based on the reduced capacitance and high-voltage ripple in the capacitor are proposed. The concept and control method were confirmed with small-scale experiments. © 1986-2012 IEEE.


Isobe T.,Tokyo Institute of Technology | Shiojima D.,Tokyo Institute of Technology | Shimada R.,Tokyo Institute of Technology | Kato K.,MERSTech Co. | Rosales Y.,MERSTech Co.
2013 IEEE Energy Conversion Congress and Exposition, ECCE 2013 | Year: 2013

This paper discusses reactive power compensators from the point of stored energy amount in the capacitor or inductor, and proposes a full-bridge configuration of semi-conductor switches with reduced equipped capacitance for reactive power compensation and its application to the shunt type static var compensator. By applying this concept, the STATCOM can be achieved with reduced sized capacitor. Additionally, the switching loss can be reduced due to its distinctive capacitor voltage waveform. Modulation technique and capacitor voltage control method based on the reduced capacitance and high voltage ripple in the capacitor are proposed. The concept and control method was confirmed with small scale experiments. © 2013 IEEE.


Isobe T.,Tokyo Institute of Technology | Kato K.,MERSTech Co. | Kojima N.,MERSTech Co. | Shimada R.,Tokyo Institute of Technology
15th International Power Electronics and Motion Control Conference and Exposition, EPE-PEMC 2012 ECCE Europe | Year: 2012

This paper proposes a new single-phase DC/AC converter topology with soft-switching operation. This converter achieves soft-switching by using DCM (discontinuous current mode) operation and a MERS based turn-off snubber topology. The DCM operation realizes zero-current turnon and the MERS snubber topology achieves zero-voltage turn-off. The proposed converter offers bi-directional power flow single-phase DC/AC conversion with soft-switching; therefore, it is attractive for grid-connecting converter for domestic renewable energy and energy storage, including PVs (Photovoltaic) and battery energy storage devices. This paper describes operation principle, control and modulation technique for this converter, and experimental verification including loss analysis with a 1-kW pilot device. © 2012 IEEE.


Isobe T.,Tokyo Institute of Technology | Kato K.,MERSTech Inc. | Kojima N.,MERSTech Inc. | Shimada R.,Tokyo Institute of Technology
IEEJ Transactions on Industry Applications | Year: 2013

With an increase in renewable energy source installations in the domestic field, bidirectional ac/dc converters are attracting attention. Efficiency, power density improvement and EMI reduction are necessary for converters in this field. Using high-frequency switching can reduce the size of passive components and help achieve a high-powerdensity converter; however, the switching losses and EMI can increase. In this study, we propose a new bidirectional ac/dc converter circuit topology that can reduce the switching losses and EMI with a soft-switching operation. The soft-switching operation is based on the DCM (discontinuous current mode) operation and a MERS (magnetic energy recovery switch)-type turn-off snubber. This paper focuses on a modulation technique applied to this converter. Experiments with a fabricated 1kW converter were conducted, and the principles of operation were confirmed. Loss analysis indicates that inductor design is the key design issue for the proposed converter. © 2014 The Institute of Electrical Engineers of Japan.


Isobe T.,Tokyo Institute of Technology | Kato K.,MERSTech Co. | Kojima N.,MERSTech Co. | Shimada R.,Tokyo Institute of Technology
IEEE Transactions on Power Electronics | Year: 2014

This paper proposes a new single-phase dc/ac converter topology with soft-switching operation. The proposed converter achieves soft-switching by using DCM (discontinuous current mode) operation and a common turn-off snubber capacitor connected to the dc terminals of a full-bridge configuration. One additional semiconductor switch is used to disconnect the snubber capacitor from the dc side, and allows the snubber capacitor to be discharged. The DCM operation realizes zero-current turn-on and the snubber capacitor achieves zero-voltage turn-off. The proposed converter can be applied to a grid-connected converter for domestic renewable energy and energy storage, including Photovoltaic and battery energy storage devices. This paper describes operation principles, control and modulation techniques as a grid-connecting converter. Experimental verification including loss analysis with a 1-kW pilot device is provided. © 2013 IEEE.


Isobe T.,Tokyo Institute of Technology | Shimada R.,Tokyo Institute of Technology | Kato K.,MERSTech Co. | Kojima N.,MERSTech Co.
2012 IEEE Energy Conversion Congress and Exposition, ECCE 2012 | Year: 2012

This paper proposes a new circuit topology for galvanic isolated DC/DC conversion. The proposed circuit mainly consists of two half-controlled bridges connected by a transformer. One half-controlled bridge consists of two diodes and two switches and a snubber capacitor. With additional clamp switches, the number of switches is low compared to conventional converter. The current flowing in the transformer is a unidirectional pulse waveform. Soft-switching can be achieved in wide operating range, even when input and/or output voltages are changed. This paper describes control and design principles to achieve soft-switching in whole operating range. The first experimental results including brief loss analysis are reported. © 2012 IEEE.


Patent
Merstech Inc. | Date: 2011-01-14

A protected power conversion device (1) includes a full-bridge MERS (100), a control circuit (200), and an ammeter (300), and is connected between a DC current source (2) and an inductive load (3). The ammeter (300) measures a current value supplied to the inductive load (3). The control circuit (200) changes the states of four reverse-conductive semiconductor switches (SW1) to (SW4) configuring the full-bridge MERS (100) to convert power output by the DC current source (2) into AC power, and supplies the AC power to the inductive load (3). When, for example, the inductive load (3) is short-circuited and malfunctions, a large current flows therethrough, and the current value detected by the ammeter (300) becomes equal to or greater than a predetermined value, the control circuit (200) turns OFF all reverse-conductive semiconductor switches (SW1) to (SW4) to cut OFF the large current.


Patent
MERSTech Inc. | Date: 2010-10-08

A power conversion device (1) comprises an inductor (L) serried-connected to an alternating-current power source (20) and a load (30), a full-bridge MERS (100) parallel-connected to the load (30), a control circuit (110), a current direction switching part (200) serried-connected between the inductor (L) and load (30), and an ammeter (300). The control circuit (110) feeds back the current detected by the ammeter (300), repeatedly turns on/off either a pair of reverse conductive semiconductor switches (SW2, SW3) or a pair of reverse conductive semiconductor switches (SW1, SW4) constituting the full-bridge MERS (100), which corresponds to the positive/negative voltage output from the alternating-current source (20), and keeps the other pair being off.


The present invention relates to an alternating-current power supply device which can improve a power factor of an alternating-current load, realizes low cost and miniaturization, and recovers magnetic energy. The alternating-current power supply device includes a bridge circuit composed of four reverse conducting semiconductor switches, a capacitor that is connected between direct-current terminals of the bridge circuit and absorbs the magnetic energy at the time of cutting off the current, an alternating-current voltage source that is connected to the induction load in series and is inserted between alternating-current terminals of the bridge circuit, and a control circuit that gives a control signal to gates of the respective reverse conducting semiconductor switches and controls on/off states of the respective reverse conducting semiconductor switches. The control circuit simultaneously controls the on/off operation of the paired reverse conducting semiconductor switches positioned on a diagonal line of the four reverse conducting semiconductor switches composing the bridge circuit, makes a control so that when one pair of the two pairs is ON, the other pair is OFF, and switches the control signal in synchronization with a voltage of the alternating-current voltage source.


Patent
MERSTech Inc. | Date: 2010-07-19

In order to provide a pulse power supply device using regenerating magnetic energy stored in a discharge circuit to a capacitor so as to use it as next discharge energy and supplying a bipolar pulse current with high repetition, a bridge circuit is composed of four inverse-conductive semiconductor switches, a charged energy source capacitor is connected to a DC terminal of the bridge circuit, and an inductive load is connected to its AC terminal. A control signal is supplied to gates of the inverse-conductive semiconductor switches, and a control is made so that when a discharge current rises, is maintained or is reduced, all the gates are turned off, and the magnetic energy of the electric current can be automatically regenerated to the energy source capacitor by a diode function of the switches. Further, a large-current power supply is inserted into a discharge circuit so as to replenish energy loss due to discharge, thereby enabling high-repetition discharge.

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