Abstract: A gate drive circuit according to an embodiment includes: a voltage detector that detects a voltage between a first terminal and a second terminal of a switching device; a delay circuit that outputs, with a delay for a predetermined time, a detected value of the voltage obtained from the voltage detector; and a first off-mode drive circuit and a second off-mode drive circuit that apply a control signal to a control terminal of the switching device for turning off the switching device, wherein the first off-mode drive circuit turns off the switching device faster than the second off-mode drive circuit, and stops its operation to turns off the switching device when the delayed voltage value output from the delay circuit exceeds a predetermined threshold value.

Abstract: An apparatus according to an embodiment includes an upper and lower arm connected between a high and a low potential end; a first capacitor connected at one end to the high potential end; a second capacitor connected at one end to the low potential end; a first regenerative rectifier circuit connected to another end of the first capacitor; a second regenerative rectifier circuit connected to another end of the second capacitor; a first conversion circuit to cause energy stored in the first capacitor to be discharged; and a second conversion circuit to cause energy stored in the second capacitor to be discharged.

Abstract: An ozone generation device includes an inverter, an ozone generator, and a reactor. The inverter turns on and off a switching element by pulse width modulation (PWM) control to convert DC power into AC power. In the ozone generator, voltage of the AC power is applied to a dielectric electrode, and discharge is generated in raw material gas flowing in a discharge gap between the dielectric electrode and a metal electrode, so that ozone is generated by the discharge. The reactor is connected in series to a dielectric electrode, and reduces an inrush current that flows through the dielectric electrode when the switching element is switched from off to on by the PWM control by the inverter.

Abstract: An apparatus according to an embodiment includes an upper and lower arm connected between a high and a low potential end; a first capacitor connected at one end to the high potential end; a second capacitor connected at one end to the low potential end; a first regenerative rectifier circuit connected to another end of the first capacitor; a second regenerative rectifier circuit connected to another end of the second capacitor; a first conversion circuit to cause energy stored in the first capacitor to be discharged; and a second conversion circuit to cause energy stored in the second capacitor to be discharged.

Abstract: An ozone generation device includes an inverter, an ozone generator, and a reactor. The inverter turns on and off a switching element by pulse width modulation (PWM) control to convert DC power into AC power. In the ozone generator, voltage of the AC power is applied to a dielectric electrode, and discharge is generated in raw material gas flowing in a discharge gap between the dielectric electrode and a metal electrode, so that ozone is generated by the discharge. The reactor is connected in series to a dielectric electrode, and reduces an inrush current that flows through the dielectric electrode when the switching element is switched from off to on by the PWM control by the inverter.

Abstract: According to an embodiment, there is provided an apparatus which can hold down an energy loss and can avoid an increase in size. The apparatus includes a cell including a floating capacitor connected in parallel to an upper-side switching element and a lower-side switching element; an upper arm include including first switch circuits, each including a first switching element, a first diode and a first capacitor, are connected in series; a lower arm including second switch circuits, each including a second switching element, a second diode and a second capacitor, are connected in series; and a circuit which connects a low-side terminal of the cell and a low-side terminal of the first capacitor and connects a high-side terminal of the cell and a high-side terminal of the second capacitor.

Abstract: According to an embodiment, there is provided an apparatus which can hold down an energy loss and can avoid an increase in size. The apparatus includes a cell including a floating capacitor connected in parallel to an upper-side switching element and a lower-side switching element; an upper arm include including first switch circuits, each including a first switching element, a first diode and a first capacitor, are connected in series; a lower arm including second switch circuits, each including a second switching element, a second diode and a second capacitor, are connected in series; and a circuit which connects a low-side terminal of the cell and a low-side terminal of the first capacitor and connects a high-side terminal of the cell and a high-side terminal of the second capacitor.

Abstract: A power supply system of an embodiment has a plurality of power conditioners, an acquisition device, and a search instruction generator. The power conditioners convert a form of electrical power generated by a plurality of electrical generators into a different form of electrical power. The acquisition device acquires a respective information regarding power output from each of the plurality of power conditioners. The search instruction generator generates and outputs an operating point search instruction to one or more power conditioners being lower in a ratio of output power with respect to a reference power by at least a prescribed degree than one or more different power conditioners, wherein the reference power is given, based on the maximum output power or rated power of the corresponding electrical generator, or based on the maximum output power or rated power of the power conditioner.

Abstract: A power conversion device includes a first switch and a second switch connected in series between a positive electrode and a negative electrode of a first power supply. A first node is between the first and second switches. The first node can be connected to a load. A first diode has an anode connected to the first node and a cathode connected to the positive electrode of the first power supply. A third switch is connected between a positive electrode of a second power supply and the positive electrode of the first power supply. A first timer is connected to a gate electrode of the third switch. A first comparator has a first input that is connected to a gate electrode of the first switch, a second input at which a reference voltage can be received, and an output that is connected to the first timer.

Abstract: A control device includes a searching unit increasing or decreasing, at a predetermined step width, an operation voltage or an operation current of a power supply connected to a power converter to search a maximum power point of the power supply, a consecution time determining unit determining whether or not the searching unit has consecutively increased or decreased the operation voltage of the power supply or the operation current thereof, and a step width increasing unit increasing the step width upon determination by the consecution time determining unit that the increase or the decrease has been consecutively executed by a predetermined number of times.

Abstract: A control device includes a searching unit increasing or decreasing, at a predetermined step width, an operation voltage or an operation current of a power supply connected to a power converter to search a maximum power point of the power supply, a consecution time determining unit determining whether or not the searching unit has consecutively increased or decreased the operation voltage of the power supply or the operation current thereof, and a step width increasing unit increasing the step width upon determination by the consecution time determining unit that the increase or the decrease has been consecutively executed by a predetermined number of times.

Abstract: A semiconductor device according to one embodiment includes a first normally-off type transistor including a first source, a first drain, a first gate, and a first body diode, a second normally-off type transistor including a second source connected to the first source, a second drain, a second gate connected to the first gate, and a second body diode, a normally-on type transistor including a third source connected to the first drain, a third drain, and a third gate connected to the second drain, and a diode including an anode connected to the second drain and a cathode connected to the third drain.

Abstract: A power conversion device includes a first switch and a second switch connected in series between a positive electrode and a negative electrode of a first power supply. A first node is between the first and second switches. The first node can be connected to a load. A first diode has an anode connected to the first node and a cathode connected to the positive electrode of the first power supply. A third switch is connected between a positive electrode of a second power supply and the positive electrode of the first power supply. A first timer is connected to a gate electrode of the third switch. A first comparator has a first input that is connected to a gate electrode of the first switch, a second input at which a reference voltage can be received, and an output that is connected to the first timer.

Abstract: According to one embodiment, a switch includes a first element with a first withstand voltage, a second element whose withstand voltage is lower than the first withstand voltage, a diode which is connected between a positive electrode of the first element and a positive electrode of the second element in such a manner that a direction from the positive electrode of the second element toward the positive electrode of the first element is a forward direction and whose withstand voltage is equal to the first withstand voltage, a negative electrode of the first element and a negative electrode of the second element being connected, and a circuit configured to apply a positive voltage to the positive terminal output a pulse lower than the first withstand voltage when the first element goes off.

Abstract: A power supply system of an embodiment has a plurality of power conditioners, an acquisition device, and a search instruction generator. The power conditioners convert a form of electrical power generated by a plurality of electrical generators into a different form of electrical power. The acquisition device acquires a respective information regarding power output from each of the plurality of power conditioners. The search instruction generator generates and outputs an operating point search instruction to one or more power conditioners being lower in a ratio of output power with respect to a reference power by at least a prescribed degree than one or more different power conditioners, wherein the reference power is given, based on the maximum output power or rated power of the corresponding electrical generator, or based on the maximum output power or rated power of the power conditioner.

Abstract: A variable-flux motor drive system including a permanent-magnet motor including a permanent magnet, an inverter to drive the permanent-magnet motor, and a magnetize device to pass a magnetizing current for controlling flux of the permanent magnet. The permanent magnet is a variable magnet whose flux density is variable depending on a magnetizing current from the inverter. The magnetize device passes a magnetizing current that is over a magnetization saturation zone of magnetic material of the variable magnet. This system improves a flux repeatability of the variable magnet and a torque accuracy.

Abstract: A semiconductor device according to one embodiment includes a first normally-off type transistor including a first source, a first drain, a first gate, and a first body diode, a second normally-off type transistor including a second source connected to the first source, a second drain, a second gate connected to the first gate, and a second body diode, a normally-on type transistor including a third source connected to the first drain, a third drain, and a third gate connected to the second drain, and a diode including an anode connected to the second drain and a cathode connected to the third drain.

Abstract: In a voltage adjusting apparatus connected in series to a system, an output of an AC/DC converter thereof is reduced. The apparatus includes a second serial transformer having a primary side connected in series to a secondary side of a first serial transformer having a primary side connected in series between a power supply and a load and to a secondary side of a parallel transformer having a primary side connected in parallel between the power supply and the load; and a first AC/DC converter having an AC side connected to a secondary side of the second serial transformer. The first AC/DC converter has a switching element connected between an AC terminal and a DC terminal, an antiparallel diode, and a capacitor.

Abstract: A reactive power compensator according to an embodiment comprises: multilevel inverter circuits respectively constituting each of the three phases; a filter circuit for reducing harmonics connected between the output terminals of each of the multilevel inverter circuits and a power system interconnection terminal; and a control section for causing prescribed three-phase AC voltage to be output by controlling each of said multilevel inverter circuits. Each of the multilevel inverter circuits is constituted by connecting in series one or more single-phase full-bridge single-pulse inverters and is arranged to convert DC voltage to respective positive and negative single-pulse voltages once per cycle of the fundamental wave of the voltage instruction value.

Abstract: According to one embodiment, a switch includes a first element with a first withstand voltage, a second element whose withstand voltage is lower than the first withstand voltage, a diode which is connected between a positive electrode of the first element and a positive electrode of the second element in such a manner that a direction from the positive electrode of the second element toward the positive electrode of the first element is a forward direction and whose withstand voltage is equal to the first withstand voltage, a negative electrode of the first element and a negative electrode of the second element being connected, and a circuit configured to apply a positive voltage to the positive terminal output a pulse lower than the first withstand voltage when the first element goes off.