Abstract: According to one embodiment, a semiconductor device includes a semiconductor circuit and an electric-power supply. The semiconductor circuit includes a main element including a switching element and an antiparallel diode, a reverse voltage application circuit including a high-speed free wheeling diode, a capacitor and an auxiliary element, a main element drive circuit, and an auxiliary element drive circuit. The electric-power supply is configured to supply electric-power to the capacitor, the main element drive circuit and the auxiliary element drive circuit, and has a voltage lower than the withstand voltage of the main element.

Abstract: According to one embodiment, a semiconductor switch includes a main element including a switching element and an antiparallel diode, and a reverse voltage application circuit. The reverse voltage application circuit includes an auxiliary electric-power supply, a high-speed free wheeling diode, an auxiliary element, and a capacitor. The high-speed free wheeling diode comprises a plurality of diodes connected in series.

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 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: Disclosed is a power conversion device which achieves reductions in switching loss due to a reverse recovery current and heat generation loss. Specifically disclosed is a power conversion device provided with a cascode element configured by electrically connecting a normally-on switching element and a normally-off switching element in series and connecting a gate terminal of the normally-on switching element and a source terminal of the normally-off switching element via a cascode connection diode, and a high-speed diode electrically connected in parallel with the cascode element and having a cathode region connected to a positive electrode terminal and an anode region connected to a negative electrode terminal.

Abstract: A semiconductor switch is provided with a main element having reverse conductivity and serving as a voltage-driven switching element having a high withstand voltage, an auxiliary element serving as a voltage-driven switching element having a withstand voltage lower than that of the main element, and a high-speed freewheel diode having a withstand voltage equal to that of the main element, wherein a negative pole of the main element is connected to a negative pole of the auxiliary element to define the positive pole of the main element as a positive pole terminal and the positive pole of the auxiliary element as a negative pole terminal, and the high-speed freewheel diode is parallel-connected between the positive pole terminal and the negative pole terminal so that a direction from the negative pole terminal toward the positive pole terminal constitutes a forward direction.

Abstract: According to one embodiment, a semiconductor switch includes a first element that includes a switching element and an anti-parallel diode. The switching element has a breakdown voltage and is coupled to a control terminal and second and third terminals. The semiconductor switch further includes a second element having a breakdown voltage lower than that of the first element. The second element is coupled to a control terminal and second and third terminals. The semiconductor switch also includes a flyback diode having a breakdown voltage substantially similar to that of the first element. A negative electrode of the first element is connected to a negative electrode of the second element and the flyback diode is connected in parallel between a positive terminal of the first element and a positive terminal of the second element. The control terminal for the first element and the control terminal for the second element are coupled to one or more control circuits independently of each other.

Abstract: The present invention includes: an inverter 1 configured to perform pulse wide modulation on an output from a DC power source 5; a first capacitor pair 41 provided at an input side of the inverter and including two capacitors serially connected to form a neutral point; a second capacitor pair 42 provided at an output side of the inverter and including two capacitors serially connected to form a neutral point; a bypass path g for a leakage current formed by connecting the neutral point of the first capacitor pair and the neutral point of the second capacitor pair to each other; at least one common mode choke coil 3 provided between the first capacitor pair and the second capacitor pair and configured to suppress a common mode current generated in the inverter; and an output filter 2 configured to convert a voltage, which is outputted from the inverter and subjected to the pulse wide modulation, into a voltage in a sine wave form.

Abstract: An electric power conversion system includes a DC power supply, plural main circuit switching devices bridge-connected to carry out DC/AC convert, having freewheeling diodes connected in reverse parallel thereto, respectively, and a reverse voltage application circuit for applying a reverse voltage smaller than the DC power supply to each freewheeling diode, upon a cutoff of back-flow current of the freewheeling diode, the reverse voltage application circuit being composed of a series connection of a low-voltage DC power supply, a reverse voltage application switching device having a lower withstand voltage than the main circuit switching devices and adapted to turn on upon a reverse recovery of the freewheeling diode, and an auxiliary diode having a shorter reverse recovery time than the freewheeling diode, the reverse voltage application switch being a device having holes as a majority carrier.

Abstract: A semiconductor switch is provided with a main element having reverse conductivity and serving as a voltage-driven switching element having a high withstand voltage, an auxiliary element serving as a voltage-driven switching element having a withstand voltage lower than that of the main element, and a high-speed freewheel diode having a withstand voltage equal to that of the main element, wherein a negative pole of the main element is connected to a negative pole of the auxiliary element to define the positive pole of the main element as a positive pole terminal and the positive pole of the auxiliary element as a negative pole terminal, and the high-speed freewheel diode is parallel-connected between the positive pole terminal and the negative pole terminal so that a direction from the negative pole terminal toward the positive pole terminal constitutes a forward direction.

Abstract: To provide a power converter, comprising: a pair of main circuit switching elements to which diodes are connected; a means for generating a first PWM basic signal for driving a main circuit switching element; and a reverse voltage application circuit to be operated, triggered by a second PWM basic signal which differs from the first PWM basic signal only in phase.

Abstract: A variable magnetic flux motor drive system includes: a variable magnetic flux motor having a variable magnet which is a low-coercive permanent magnet; an inverter that drives the variable magnetic flux motor 1; an inverter as a magnetization unit which supplies a magnetization current for controlling a magnetic flux of the variable magnet; and a boosting unit boosting an input DC voltage to a predetermined target value to output it to the inverter. The variable magnetic flux motor drive system makes it possible to achieve size reduction and high efficiency, while securing a voltage required for supplying a magnetization current when controlling the magnetic flux of the variable magnet.

Abstract: There are provided: sets of pairs of main circuit switching elements (4u), (4x) that supply power to a load, connected in series with a DC power source; free-wheel diodes (5u), (5x) connected in anti-parallel with these main circuit switching elements; and a reverse voltage application circuit (8) that applies reverse voltage smaller than the DC voltage source to the free-wheel diodes when these free-wheel diodes cut off. The reverse voltage application circuit includes a current suppression circuit (10) that suppresses the main circuit current flowing in the low-voltage DC voltage power source on reverse recovery of the free-wheel diodes.

Abstract: To provide a power converter, comprising: a pair of main circuit switching elements to which diodes are connected; a means for generating a first PWM basic signal for driving a main circuit switching element; and a reverse voltage application circuit to be operated, triggered by a second PWM basic signal which differs from the first PWM basic signal only in phase.

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: An electric power conversion system including a direct current power supply, plural main circuit switching devices bridge-connected to convert the direct current to alternating current, including free wheeling diodes connected in reverse parallel thereto, respectively, and a reverse voltage application circuit applying a reverse voltage smaller than the direct current power supply to each free wheeling diode, upon cutoff of back-flow current of the free wheeling diode. The reverse voltage application circuit includes in series connection a low-voltage direct current power supply having a voltage lower than the direct current power supply, a reverse voltage application switching device having holes as a majority current and a lower withstand voltage than the main circuit switching devices and adapted to turn on upon reverse recovery of the free wheeling diode, and an auxiliary diode having a shorter reverse recovery time than the free wheeling diode.

Abstract: There are provided: sets of pairs of main circuit switching elements (4u), (4x) that supply power to a load, connected in series with a DC power source; free-wheel diodes (5u), (5x) connected in anti-parallel with these main circuit switching elements; and a reverse voltage application circuit (8) that applies reverse voltage smaller than the DC voltage source to the free-wheel diodes when these free-wheel diodes cut off. The reverse voltage application circuit includes a current suppression circuit (10) that suppresses the main circuit current flowing in the low-voltage DC voltage power source on reverse recovery of the free-wheel diodes.

Abstract: A vehicle power source device is provided with an DC/DC converter (4) having a high-frequency insulating transformer (6) that converts power from an overhead power line to DC power, and a CVCF inverter (1) that converts the DC power supplied from this DC/DC converter (4) to AC power; the AC power converted by this CVCF inverter (1) is supplied to equipment such as for on-board lighting.

Abstract: There are provided: a main three-phase full-wave rectifier (8) that converts three-phase AC (R phase, S phase, T phase) into DC; a transformer (9) that outputs AC of a total of six phases corresponding to the points that equally divide by three the arcs drawn in a transformer vector diagram in which an equilateral triangle is formed whereof the R phase, S phase and T phase are vertices, centered on each vertex and linking the remaining two points; and two auxiliary three-phase full-wave rectifiers (12) and (13) in that convert into DC the six-phase AC that is output from the transformer (9), the output lines of the main three-phase full-wave rectifier (8) and two auxiliary three-phase full-wave rectifiers (12) and (13) being connected in parallel. The current flowing in the DC line through the transformer can therefore be reduced to ⅓ of the whole in the case of an 18-pulse rectifier, so enabling the capacity of the transformer to be reduced.

Abstract: There are provided: a main three-phase full-wave rectifier (8) that converts three-phase AC (R phase, S phase, T phase) into DC; a transformer (9) that outputs AC of a total of six phases corresponding to the points that equally divide by three the arcs drawn in a transformer vector diagram in which an equilateral triangle is formed whereof the R phase, S phase and T phase are vertices, centered on each vertex and linking the remaining two points; and two auxiliary three-phase full-wave rectifiers (12) and (13) that convert into DC the six-phase AC that is output from the transformer (9), the output lines of the main three-phase full-wave rectifier (8) and two auxiliary three-phase full-wave rectifiers (12) and (13) being connected in parallel. The current flowing in the DC line through the transformer can therefore be reduced to ⅓ of the whole in the case of an 18-pulse rectifier, so enabling the capacity of the transformer to be reduced.