JP2013162658A5 - - Google Patents

Claims (16)

A power conversion device that performs power conversion between a polyphase AC input terminal and a polyphase AC output terminal,
A transformer comprising a primary winding connected to the input terminal and a secondary winding comprising a plurality of mutually isolated single-phase open windings; and a switching element having an input terminal at each single-phase open winding A plurality of converter cells that are connected to a line and whose output ends are connected in series with each other and connected to the output terminals of each phase and perform single-phase AC / single-phase AC conversion, and control means for controlling on / off of the switching element And
Each converter cell converts a single-phase AC voltage from the input terminal into a DC voltage of three or more levels and outputs it to a capacitor series body, and converts the DC voltage from the capacitor series body into a single-phase AC voltage. An electric power converter comprising: an inverter that converts and outputs the output to the output terminal. 2. The power converter according to claim 1, wherein the control means comprises bus voltage control means for controlling a DC bus voltage, which is a voltage of the capacitor series body of each converter cell, to a predetermined voltage. The bus voltage control means is configured so that an average value over the different phases of the DC bus voltages in the converter cells connected to different phases of the output terminal becomes a predetermined bus voltage command value. The power converter according to claim 2, further comprising an average voltage control means for controlling an input current effective component of the next winding. The bus voltage control means includes: the converter cells connected to different phases of the output terminals so that the DC bus voltages in the converter cells connected to different phases of the output terminals are uniformly balanced with each other. 4. The power conversion device according to claim 2, further comprising interphase balance control means for controlling a voltage command value of the inverter. The bus voltage control means is configured so that the DC bus voltages in the plurality of converter cells connected in series with each other of the output terminals are uniformly balanced with respect to each other. 5. The power conversion device according to claim 2, further comprising an in-phase balance control unit configured to control a voltage command value of the inverter. The capacitor series body is composed of a positive-side capacitor and a negative-side capacitor connected in series with each other, and the DC-bus voltage of the converter cell is applied to the positive-side capacitor and the negative-side It consists of the negative side DC bus voltage applied to the capacitor,
The bus voltage control means includes a voltage to the switching element that constitutes the converter and / or the inverter so that the positive DC bus voltage and the negative DC bus voltage are uniformly balanced with each other in each converter cell. The power converter according to any one of claims 2 to 5, further comprising an in-cell balance control means for controlling the command value. The control means includes a plurality of the converters connected in series for each phase of the output terminal so as to reduce harmonic components contained in an input current to the input terminal and / or an output voltage from the output terminal. 7. The timing for switching the converter and / or the switching element constituting the inverter in the converter cell is controlled so as to be shifted with respect to each other in the plurality of converter cells. 8. The power converter described. The control means includes modulation means for performing pulse width modulation control using a carrier signal, and the modulation means shifts the phase of the carrier signal to each other by the plurality of the converter cells, thereby performing the switching. 8. The power conversion device according to claim 7, wherein the switching timing of the elements is shifted between the plurality of converter cells. 9. The electric power according to claim 1, wherein each of the primary windings is composed of a plurality of transformers connected in parallel to the input terminal. Conversion device. The power converter according to any one of claims 1 to 8, wherein the transformer includes a plurality of the secondary windings with respect to the primary winding of one phase. The inputs of the plurality of converter cells connected to the output terminal with the same number of phases of the multiphase alternating current of the input terminal and the multiphase alternating current of the output terminal, the output ends of which are connected in series with each other The end is connected in parallel with each other through the transformer to the input terminal of the same phase as the phase of the output terminal to which the output end is connected. The power conversion device according to item 1. Before Kio phase AC is a three-phase alternating current, the primary winding of the transformer, the power conversion device according to any one of claims 1 to 11, characterized in that a star connection three-phase . The power converter according to claim 12, wherein the iron core of the transformer is composed of four or more iron cores. The group of semiconductor elements including the switching elements and diodes constituting the converter or the inverter of each converter cell is housed in one module. The power converter device described in 1. At least one of the switching element and the diode constituting the converter or the inverter of each converter cell is formed of a wide band gap semiconductor material having a larger band gap than silicon. The power converter according to any one of claims 1 to 14. The power converter according to claim 15, wherein the wide band gap semiconductor material is silicon carbide, a gallium nitride-based material, or diamond.