Abstract: A method of controlling a single-phase voltage source AC/DC converting circuit has internal equivalent impedance as seen from an AC terminal, for converting power from a DC voltage source connected to a DC terminal to single-phase AC power or for converting single-phase AC power from a single-phase AC source connected to the AC terminal to DC power in accordance with a pulse width of a gate signal generated based on a PWM command.

Abstract: A static synchronous compensator that generates a second axis voltage command from the difference between the DC voltage converted by a single-phase voltage AC-DC conversion circuit and a set DC voltage command. When the voltage (the voltage of an AC terminal) of the single-phase AC power system increases, since the difference between the voltage of the AC terminal and an internal electromotive force increases, the static synchronous compensator carries out a PWM control to decreases the voltage of the AC terminal side of the single-phase voltage AC-DC conversion circuit. Since the voltage of the single-phase voltage AC-DC conversion circuit becomes lower than the voltage of the single-phase AC power system, an ineffective current flows from single-phase AC power system in the static synchronous compensator so that the voltage of the single-phase AC power system can be decreased.

Abstract: A static synchronous compensator that generates a second axis voltage command from the difference between the DC voltage converted by a single-phase voltage AC-DC conversion circuit and a set DC voltage command. When the voltage (the voltage of an AC terminal) of the single-phase AC power system increases, since the difference between the voltage of the AC terminal and an internal electromotive force increases, the static synchronous compensator carries out a PWM control to decreases the voltage of the AC terminal side of the single-phase voltage AC-DC conversion circuit. Since the voltage of the single-phase voltage AC-DC conversion circuit becomes lower than the voltage of the single-phase AC power system, an ineffective current flows from single-phase AC power system in the static synchronous compensator so that the voltage of the single-phase AC power system can be decreased.

Abstract: A distributed power system is designed to continuously supply electric power to a load even when a system voltage of the electric power system becomes abnormal. The distributed power system includes a DC/DC converter to convert DC current generated by solar power generation facility to DC current with a predetermined output voltage, and an inverter to convert the DC current to an AC current which is output to an electric power system via a system interconnect switch. When the system voltage of the electric power system is abnormal, a control device makes the system interconnect switch open to switch operation modes of the DC/DC converter and inverter to a self-sustaining operation without stopping, and supplies electric power to a load connected between the inverter and the system interconnect switch.

Abstract: A method and a single-phase voltage type AC/DC converting device and a three-phase voltage type AC/DC converting device arranged between a load and a distribution network. The converting devices are capable of contributing to stabilize a system frequency and a system voltage. By applying an autonomous parallel operation control technique of an AC/DC converter to a load, which receives power from a distribution network, drooping characteristics (governor-free characteristics) for a frequency of active power and voltage-maintaining characteristics (V-Q characteristics) may be obtained. The governor-free characteristics automatically decrease and increase received power when the system frequency decreases and increases, so that even the load may contribute to stabilize the system frequency. The V-Q characteristics generates/absorbs reactive power so as to maintain a voltage at a receiving end constant regardless of load power to further stabilize the system voltage.

Abstract: A method of controlling a single-phase voltage source AC/DC converting circuit has internal equivalent impedance as seen from an AC terminal, for converting power from a DC voltage source connected to a DC terminal to single-phase AC power or for converting single-phase AC power from a single-phase AC source connected to the AC terminal to DC power in accordance with a pulse width of a gate signal generated based on a PWM command.

Abstract: A single-phase voltage source DC-AC power converter includes (a) a single-phase voltage source DC-AC power converting circuit having a gate signal generator that detects a single-phase AC output current at an AC terminal and that generates gate signals for making values of a PWM command and the single-phase AC output current identical, and (b) target current producing means that produces the PWM command such that a DC component included in the single-phase AC output voltage at the AC terminal becomes zero.

Abstract: An automatic synchronous parallelization apparatus capable of suppressing an inrush current by automatically adjusting the magnitude, the frequency, and the phase of the voltage when a single-phase voltage-type DC-to-AC converting device performing an autonomous parallel operation is connected in parallel with an external single-phase AC voltage source. The automatic synchronous parallelization apparatus includes a synchronization detecting circuit, a voltage amplitude command value generating circuit, and a frequency command value generating circuit.

Abstract: A single-phase voltage source AC/DC converter according to the present invention generates a second axis voltage command from difference between a DC voltage detection value at a DC terminal and a DC voltage command value and controls a DC voltage by increasing and decreasing active power with the second axis voltage command. For example, the voltage at the DC terminal is increased by decreasing active power when the DC voltage detection value at the DC terminal is lower than the DC voltage command, while the DC voltage detection value at the DC terminal is decreased by increasing the active power when the DC voltage detection value at the DC terminal is higher than the DC voltage command.

Abstract: The present invention is a single-phase voltage source DC-AC power converter and a three-phase voltage source DC-AC power converter.

Abstract: A single-phase voltage source AC/DC converter according to the present invention generates a second axis voltage command from difference between a DC voltage detection value at a DC terminal and a DC voltage command value and controls a DC voltage by increasing and decreasing active power with the second axis voltage command. For example, the voltage at the DC terminal is increased by decreasing active power when the DC voltage detection value at the DC terminal is lower than the DC voltage command, while the DC voltage detection value at the DC terminal is decreased by increasing the active power when the DC voltage detection value at the DC terminal is higher than the DC voltage command.

Abstract: An object is to provide a single-phase voltage type AC/DC converting device and a three-phase voltage type AC/DC converting device arranged between a load and a distribution network and is capable of contributing to stabilize a system frequency and a system voltage, and a stabilization controlling method of the system frequency and the system voltage. By applying an autonomous parallel operation control technique of an AC/DC converter to a load, which receives power from a distribution network, drooping characteristics (governor-free characteristics) for a frequency of active power and voltage-maintaining characteristics (V-Q characteristics) may be obtained. The governor-free characteristics are the characteristics to automatically decrease received power when the system frequency decreases and automatically increase the received power when this increases, so that even the load may contribute to stabilize the system frequency.

Abstract: An automatic synchronous parallelization apparatus capable of suppressing an inrush current by automatically adjusting the magnitude, the frequency, and the phase of the voltage when a single-phase voltage-type DC-to-AC converting device performing an autonomous parallel operation is connected in parallel with an external single-phase AC voltage source. The automatic synchronous parallelization apparatus includes a synchronization detecting circuit, a voltage amplitude command value generating circuit, and a frequency command value generating circuit.

Abstract: An electric power source in which a plurality of inverters operate on the same frequency and the plurality of inverters are connected in parallel so that a resistance value expressed by (1??·G)/(?·G) where ? is the output voltage feedback gain, ? is the output current feed forward gain, and G is the inverter current gain, is made to be the equivalent output impedance; and is an electrical power source in which the cross-current between the inverters are made to be an acceptable value or below by adjusting the output of each of the inverters by controlling the equivalent output impedance by modifying both or either one of the output voltage feedback gain ? or the output current feed forward gain ?.

Abstract: The present invention is a single-phase voltage source AC-DC power converter and a three-phase voltage source AC-DC power converter.

Abstract: The present invention is an electric power source in which a plurality of inverters operate on the same frequency and the plurality of inverters are connected in parallel so that a resistance value expressed by (1??·G)/(?·G) where ? is the output voltage feedback gain, ? is the output current feed forward gain, and G is the inverter current gain, is made to be the equivalent output impedance; and is an electrical power source in which the cross-current between the inverters are made to be an acceptable value or below by adjusting the output of each of the inverters by controlling the equivalent output impedance by modifying both or either one of the output voltage feedback gain ? or the output current feed forward gain ?.

Abstract: The present invention is an electric power source in which a plurality of inverters operate on the same frequency and the plurality of inverters are connected in parallel so that a resistance value expressed by (1??·G)/(?·G) where ? is the output voltage feedback gain, ? is the output current feed forward gain, and G is the inverter current gain, is made to be the equivalent output impedance; and is an electrical power source in which the cross-current between the inverters are made to be an acceptable value or below by adjusting the output of each of the inverters by controlling the equivalent output impedance by modifying both or either one of the output voltage feedback gain ? or the output current feed forward gain ?.

Abstract: The present invention relates to a polishing composition for silicon wafer comprising silica, a basic compound, a polyaminopolycarboxylic acid compound having hydroxy group, and water. The polishing composition can prevent metal contamination by nickel, chromium, iron, copper or the like, particularly copper contamination in polishing of silicon wafer.

Abstract: A three-phase voltage-fed AC/DC converter includes a conversion circuit which converts power from a DC voltage source to three-phase AC power. The converter further includes a UM conversion circuit which carries out dq conversion of the three-phase output voltage, a superior voltage control circuit which outputs a voltage reference vector based on a superior reference vector and an output voltage vector obtained by the UM conversion circuit, an inferior voltage control circuit which outputs a PWM reference based on the voltage reference vector and the output voltage vector, and a frequency control circuit which synchronizes a value generated based on a q-axis component from the UM conversion circuit with a rotation angle of a conversion matrix in the UM conversion circuit.

Abstract: The present invention is a method for producing a polishing agent in which silica particles are dispersed in an aqueous solution, comprising at least a step of removing metal compound ions from a prepared silica sol by ion exchange (B); a step of purifying further the ion-exchanged silica sol (D); a step of adding alkali metal hydroxide to the purified silica sol (F); and a step of adding an acid to the silica sol to which the alkali metal hydroxide is added (G). There is provided a method for producing a polishing agent which can extremely effectively suppress metal contamination when a silicon wafer or the like is polished can be produced.