Abstract: A power supply system includes: a synchronous generator connected to a three-phase power distribution system that is connected to a consumer load; an inverter that is connected to the power distribution system, supplies power to the consumer load, and compensates for unbalanced current of the synchronous generator; and a control device that generates a gate command for controlling the inverter. The control device: generates, based on a three-phase voltage and current output from the inverter, a target output voltage which is an amplitude of a vector in a complex plane combining voltages of three phases, and a target output phase which is a phase of the vector in the complex plane combining the voltages of three phases; generates a first compensation voltage, based on a current negative-phase-sequence component relating to the synchronous generator; and generates a gate command from the generated values.

Abstract: An engine generator detects a DC voltage in a path from a rectifier to an inverter in controlling charge/discharge, and makes a duty ratio in switching control of a charging conductor of a power storage device higher than a duty ratio in the switching control of a discharging conductor of the power storage device when the DC voltage is higher than a target voltage of the DC voltage, and makes the duty ratio in the switching control of the discharging conductor of the power storage device higher than the duty ratio in the switching control of the charging conductor of the power storage device when the DC voltage is lower than the target voltage.

Abstract: An engine generator detects a DC voltage in a path from a rectifier to an inverter in controlling charge/discharge, and makes a duty ratio in switching control of a charging conductor of a power storage device higher than a duty ratio in the switching control of a discharging conductor of the power storage device when the DC voltage is higher than a target voltage of the DC voltage, and makes the duty ratio in the switching control of the discharging conductor of the power storage device higher than the duty ratio in the switching control of the charging conductor of the power storage device when the DC voltage is lower than the target voltage.

Abstract: When a snubber capacitor is charged to a level greater than or equal to a predetermined voltage, a protection circuit renders a clamp diode conductive to complete charging of the snubber capacitor.

Abstract: When a snubber capacitor is charged to a level greater than or equal to a predetermined voltage, a protection circuit renders a clamp diode conductive to complete charging of the snubber capacitor.

Abstract: A power converter converts DC power supplied from a first DC power supply and a second DC power supply into AC power and supplies the AC power to a load. The power converter includes a protection circuit for allowing a charging current, which is possibly to flow from the first DC power supply and the second DC power supply to a first snubber capacitor or a second snubber capacitor, to flow to another current path, when a voltage applied to the first snubber capacitor becomes a predetermined value or more or when a voltage applied to the second snubber capacitor becomes a predetermined value or more.

Abstract: A control circuit, during a positive period in which current flows from a power conversion apparatus to a load, causes a second snubber capacitor to discharge by controlling a second auxiliary switch to be turned on while a second main diode is turned on, and during a negative period in which current flows from the load to the power conversion apparatus, causes a first snubber capacitor to discharge by controlling a first auxiliary switch to be turned on while a first main diode is turned on.

Abstract: A control circuit, during a positive period in which current flows from a power conversion apparatus to a load, causes a second snubber capacitor to discharge by controlling a second auxiliary switch to be turned on while a second main diode is turned on, and during a negative period in which current flows from the load to the power conversion apparatus, causes a first snubber capacitor to discharge by controlling a first auxiliary switch to be turned on while a first main diode is turned on.

Abstract: A power converter converts DC power supplied from a first DC power supply and a second DC power supply into AC power and supplies the AC power to a load. The power converter includes a protection circuit for allowing a charging current, which is possibly to flow from the first DC power supply and the second DC power supply to a first snubber capacitor or a second snubber capacitor, to flow to another current path, when a voltage applied to the first snubber capacitor becomes a predetermined value or more or when a voltage applied to the second snubber capacitor becomes a predetermined value or more.

Abstract: A multi-quality electric power supply apparatus supplies electric power based on the demand of various loads. The multi-quality electric power supply apparatus includes an inverter having a three-phase bridge configuration with an A/C output terminal connected to a distribution line of each phase of the three-phase four-wire A/C system. A capacitor is connected among two input terminals of the D/C side of the inverter and a neutral line of the three-phase four-wire A/C system. An uninterruptable power supply device is inserted from a node point to the distribution line of the inverter in a given distribution line of one phase on the load side to compensate for a voltage drop of the distribution line and to supply a given voltage in the distribution line during an interrupted power supply.