Abstract: A voltage controller generates an AC current command value by adding a feed-forward term to a result of a control calculation performed for reducing a difference of a detected value of an AC voltage with respect to an AC voltage command value, the feed-forward term being determined by multiplying, by a gain, a detected value of primary winding current of a transformer. A current controller generates an inverter control command value by a control calculation performed for reducing a difference of a detected value of output current of the inverter with respect to the AC current command value. A PWM circuit generates a control signal for the inverter by comparing the inverter control command value with a predetermined carrier wave. When exciting inrush current is detected in a detected value of the primary winding current, the voltage controller sets the gain smaller than the gain when the exciting inrush current is not detected.

Abstract: A voltage controller generates an AC current command value by adding a feed-forward term to a result of a control calculation performed for reducing a difference of a detected value of an AC voltage with respect to an AC voltage command value, the feed-forward term being determined by multiplying, by a gain, a detected value of primary winding current of a transformer. A current controller generates an inverter control command value by a control calculation performed for reducing a difference of a detected value of output current of the inverter with respect to the AC current command value. A PWM circuit generates a control signal for the inverter by comparing the inverter control command value with a predetermined carrier wave. When exciting inrush current is detected in a detected value of the primary winding current, the voltage controller sets the gain smaller than the gain when the exciting inrush current is not detected.

Abstract: A converter includes a first diode having an anode and a cathode connected respectively to an input terminal and a first output terminal, a second diode having an anode and a cathode connected respectively to a second output terminal and the input terminal, a first transistor connected between the first output terminal and the input terminal, a second transistor connected between the input terminal and the second output terminal, and a bidirectional switch connected between the input terminal and a third output terminal and including third to sixth diodes and a third transistor. Each of the first diode, the second diode, and the third transistor is made of a wide bandgap semiconductor. Each of the first and second transistors and the third to sixth diodes is made of a semiconductor other than the wide bandgap semiconductor.

Abstract: A bidirectional insulated DC/DC converter includes a first single-phase 3-level inverter, a second single-phase 3-level inverter, and an insulated transformer. The first single-phase 3-level inverter generates a first AC voltage between output terminals based on a first DC voltage received from a first DC circuit. The second single-phase 3-level inverter generates a second AC voltage between output terminals based on a second DC voltage received from a second DC circuit. The insulated transformer includes a primary winding that receives the first AC voltage from the output terminals and a secondary winding that receives the second AC voltage from the output terminals.

Abstract: A bidirectional insulated DC/DC converter (1) includes a first single-phase 3-level inverter (INV-A), a second single-phase 3-level inverter (INV-B), and an insulated transformer (3). The first single-phase 3-level inverter (INV-A) generates a first AC voltage (VA) between output terminals (1a, 1b) based on a first DC voltage received from a first DC circuit (5). The second single-phase 3-level inverter (INV-B) generates a second AC voltage (VB) between output terminals (2a, 2b) based on a second DC voltage received from a second DC circuit (6). The insulated transformer (3) includes a primary winding (3a) that receives the first AC voltage (VA) from the output terminals (1a, 1b) and a secondary winding (3b) that receives the second AC voltage (VB) from the output terminals (2a, 2b).

Abstract: A converter includes a first diode having an anode and a cathode connected respectively to an input terminal and a first output terminal, a second diode having an anode and a cathode connected respectively to a second output terminal and the input terminal, a first transistor connected between the first output terminal and the input terminal, a second transistor connected between the input terminal and the second output terminal, and a bidirectional switch connected between the input terminal and a third output terminal and including third to sixth diodes and a third transistor. Each of the first diode, the second diode, and the third transistor is made of a wide bandgap semiconductor. Each of the first and second transistors and the third to sixth diodes is made of a semiconductor other than the wide bandgap semiconductor.

Abstract: A bidirectional insulated DC/DC converter narrows a pulse width of an AC fundamental wave voltage corresponding to a higher DC voltage of two DC voltages, to cause effective values of the AC fundamental wave voltages to coincide with each other, and then, sets a phase difference between the AC fundamental wave voltages in accordance with a value and a direction of a current that is desired to flow. Accordingly, even when the difference between the two DC voltages greatly varies, DC power can be stably transmitted and received.

Abstract: A power conversion circuit connected to a three phase alternating current line is controlled in a PWM system. To control an arm corresponding to each phase, first to third carrier wave signals are generated. The first to third carrier wave signals include two signals having phases, respectively, offset by 180 degrees from each other. This allows a zero phase component to less frequently reach a peak value and be accordingly reduced as time averaged. This can reduce a zero phase harmonic component generated from a power supply apparatus.

Abstract: A bidirectional insulated DC/DC converter narrows a pulse width of an AC fundamental wave voltage corresponding to a higher DC voltage of two DC voltages, to cause effective values of the AC fundamental wave voltages to coincide with each other, and then, sets a phase difference between the AC fundamental wave voltages in accordance with a value and a direction of a current that is desired to flow. Accordingly, even when the difference between the two DC voltages greatly varies, DC power can be stably transmitted and received.

Abstract: An uninterruptible power supply system includes a plurality of uninterruptible power supply devices connected in parallel between a commercial AC power supply and a load; and a control unit selecting the required number of uninterruptible power supply devices for driving the load from the plurality of uninterruptible power supply devices, to cause each selected uninterruptible power supply device to be operated and to cause each remaining uninterruptible power supply device to be stopped. This control unit changes the uninterruptible power supply devices to be operated from one to another in a predetermined cycle such that the plurality of uninterruptible power supply devices are identical in operation time to one another. Accordingly, the continuous operation time of each of the uninterruptible power supply devices can be shortened, so that failures occurring in each uninterruptible power supply device can be reduced.

Abstract: A power conversion circuit connected to a three phase alternating current line is controlled in a PWM system. To control an arm corresponding to each phase, first to third carrier wave signals are generated. The first to third carrier wave signals include two signals having phases, respectively, offset by 180 degrees from each other. This allows a zero phase component to less frequently reach a peak value and be accordingly reduced as time averaged. This can reduce a zero phase harmonic component generated from a power supply apparatus.

Abstract: An uninterruptible power supply system includes a plurality of uninterruptible power supply devices (U1 to U3) connected in parallel between a commercial AC power supply (70) and a load (71); and a control unit (5) selecting the required number of uninterruptible power supply devices for driving the load (71) from the plurality of uninterruptible power supply devices (U1 to U3), to cause each selected uninterruptible power supply device to be operated and to cause each remaining uninterruptible power supply device to be stopped. This control unit (5) changes the uninterruptible power supply devices to be operated from one to another in a predetermined cycle such that the plurality of uninterruptible power supply devices (U1 to U3) are identical in operation time to one another. Accordingly, the continuous operation time of each of the uninterruptible power supply devices can be shortened, so that failures occurring in each uninterruptible power supply device can be reduced.

Abstract: A power conversion apparatus includes AC power supplies, If an abnormality occurs in any one of the AC power supplies and loads that are respectively connected to two capacitors are not balanced, voltages of the two capacitors are balanced. When an abnormality occurs in a first or second AC power supply, a first reactor is connected to a second reactor in series, a battery supplies energy to the two capacitors, and a current flowing to the first reactor is controlled by a first switch. In this manner, a voltage between the two capacitors is controlled.

Abstract: In an electric power system interconnection device, a primary power supply is connected to a load via a switch and a secondary power supply is connected to a load side of the load via a power converter to establish coordinated interconnection of the primary power supply and the secondary power supply. When the switch is opened in the event of a failure of the primary power supply, the electric power system interconnection device extinguishes an arc current flowing through the switch, at a high speed, by controlling an output current of the power converter using the load current flowing into the load as an output current command for the power converter so that uninterrupted electric power is supplied to the load.

Abstract: In a power conversion apparatus having a plurality of AC power supplies, even if an abnormality occurs in any one of the AC power supplies and loads that are respectively connected to two capacitors are not balanced, voltages of the two capacitors are balanced.

Abstract: In an electric power system interconnection device, a primary power supply is connected to a load via a switch and a secondary power supply is connected to a load side of the load via a power converter to establish coordinated interconnection of the primary power supply and the secondary power supply. When the switch is opened in the event of a failure of the primary power supply, the electric power system interconnection device extinguishes an arc current flowing through the switch at a high speed by controlling an output current of the power converter using the value of a load current flowing into the load as an output current command for the power converter so that uninterrupted electric power is supplied to the load.

Abstract: A controller for controlling power transducers to maintain a balanced three-phase output voltage with no influence on current control even when an unbalanced load is connected to a three-phase output of an inverter of the power transducer. The controller provides a stable high-precision three-phase voltage to a load by suppressing higher harmonic voltage components even when a non-linear load is connected. The controller includes a voltage regulator circuit having, for each phase, circuitry calculating a mean value of the output voltage of the inverter. The controller detects and controls deviation in the output voltage from a single-phase mean voltage command. The controller determines a voltage deviation ratio from the deviation and multiplies each output voltage value by the voltage deviation ratio and uses the product as a new voltage detection value.

Abstract: The present invention provides a power inverting apparatus capable of coping with an abrupt change in phase of input voltage within a certain range and operating in a stable manner continuously. According to a first aspect of the present invention, a power inverting apparatus comprises a converter unit for changing ac voltage supplied by an ac voltage source into dc voltage, an inverter unit for changing dc voltage supplied by converter unit into ac voltage, and an input voltage control unit that when the polarity of ac voltage supplied by the ac voltage source inconsistent with the one of ac voltage supplied by the inverter unit, cuts off ac voltage to be supplied to the converter unit.

Abstract: A power conversion apparatus includes: a reference signal generating circuit for generating a reference signal which has a first frequency; a first power converter for converting D.C. power into A.C. power which has the first frequency; a transformer connected to the first power converter; a carrier signal generating circuit for generating a carrier signal which has a second frequency which is higher than the first frequency; a second power converter having a plurality of switching devices and as well as converting the output from the transformer into A.C.

Abstract: 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.