Abstract: In a DC/DC converter, in first power transmission in which power is transmitted from a first DC power source to a second DC power source, on/off drive of a positive electrode-side switching element and a negative electrode-side switching element is stopped in a third bridge circuit on the power-receiving side. When a power transmission amount by the first power transmission is smaller than a first reference value, a control circuit lowers the switching frequency of the switching elements of a first bridge circuit and a second bridge circuit on the power-transmitting side and a fourth bridge circuit on the power-receiving side, compared with when the power transmission amount is equal to or greater than the first reference value.

Abstract: A first leg includes a first switch circuit disposed between a first node to which a positive electrode of a DC power supply is connected and a second node and a second switch circuit disposed between the second node and a third node. A first filter circuit includes a first capacitor. A bridge circuit includes a second leg and a third leg that are disposed in parallel between the first node and the third node. A clamp circuit includes a bidirectional switch disposed between a fourth node that is a midpoint of the second leg and a fifth node that is a midpoint of the third leg. A second filter circuit includes a first reactor and a second reactor.

Abstract: A power conversion device converts a direct-current power on the DC side of the power conversion device to an alternating-current power by an inverter circuit having a plurality of semiconductor switching elements, and outputs the AC power from the AC side of the power conversion device. A current detector detects a reactor current output from the inverter circuit. As overcurrent detector detects overcurrent in a control mode in which the reactor current is caused to follow a reactor current command value, control circuit starts an overcurrent mode in which a time period where the reactor current monotonically decreases is provided. In the overcurrent mode, whether to switch the overcurrent mode to the normal control mode is determined based on the reactor current or in accordance with a timing corresponding to a zero-cross point of a voltage or current on the AC side.

Abstract: The connection distance between a first snubber circuit and the positive electrode of a first semiconductor element is shorter than the connection distance between the first snubber circuit and the positive electrode of a third semiconductor element. The connection distance between the first snubber circuit and the negative electrode of a fourth semiconductor element is shorter than the connection distance between the first snubber circuit and the negative electrode of a second semiconductor element. The connection distance between a second snubber circuit and the positive electrode of the third semiconductor element is shorter than the wiring distance between the second snubber circuit and the positive electrode of the first semiconductor element, and the connection distance between the second snubber circuit and the negative electrode of the second semiconductor element is shorter than the wiring distance between the second snubber circuit and the negative electrode of the fourth semiconductor element.

Abstract: A bridge circuit includes a first leg and a second leg arranged in parallel between the first node and the third node. A clamp circuit includes a third leg including a first bidirectional switch disposed between a fourth node that is a midpoint of the first leg and a fifth node that is a midpoint of the second leg. A first reactor is connected with the fourth node and a sixth node, and a second reactor is connected with a fifth node and a seventh node. A fourth leg includes a second bidirectional switch disposed between the second node and the fourth node or the fifth node.

Abstract: An insulating transformer includes a plurality of sub-insulating transformers connected in series. Polarity directions of all sub-windings are identical. When a current I flows from a first main terminal to a third main terminal through the first sub-winding, an interphase capacitance, and the second sub-winding, excitation inductance of the first sub-winding and excitation inductance of the second sub-winding are configured to have opposite polarities.

Abstract: A first capacitor and a second capacitor are connected in series through a neutral point on the DC side of an inverter. A first converter receives an input voltage from a power source and outputs a first DC voltage to the first capacitor. A second converter receives a common input voltage and outputs a second DC voltage to the second capacitor. A control circuit controls the first converter such that the first DC voltage is controlled in accordance with a preset first voltage command value and controls the second converter such that the second DC voltage is controlled in accordance with a second voltage command value set equivalent to the first voltage command value.

Abstract: In a DC/DC converter, in first power transmission in which power is transmitted from a first DC power source to a second DC power source, on/off drive of a positive electrode-side switching element and a negative electrode-side switching element is stopped in a third bridge circuit on the power-receiving side. When a power transmission amount by the first power transmission is smaller than a first reference value, a control circuit lowers the switching frequency of the switching elements of a first bridge circuit and a second bridge circuit on the power-transmitting side and a fourth bridge circuit on the power-receiving side, compared with when the power transmission amount is equal to or greater than the first reference value.

Abstract: The connection distance between a first snubber circuit and the positive electrode of a first semiconductor element is shorter than the connection distance between the first snubber circuit and the positive electrode of a third semiconductor element. The connection distance between the first snubber circuit and the negative electrode of a fourth semiconductor element is shorter than the connection distance between the first snubber circuit and the negative electrode of a second semiconductor element. The connection distance between a second snubber circuit and the positive electrode of the third semiconductor element is shorter than the wiring distance between the second snubber circuit and the positive electrode of the first semiconductor element, and the connection distance between the second snubber circuit and the negative electrode of the second semiconductor element is shorter than the wiring distance between the second snubber circuit and the negative electrode of the fourth semiconductor element.

Abstract: A bridge circuit includes a first leg and a second leg arranged in parallel between the first node and the third node. A clamp circuit includes a third leg including a first bidirectional switch disposed between a fourth node that is a midpoint of the first leg and a fifth node that is a midpoint of the second leg. A first reactor is connected with the fourth node and a sixth node, and a second reactor is connected with a fifth node and a seventh node. A fourth leg includes a second bidirectional switch disposed between the second node and the fourth node or the fifth node.

Abstract: A first leg includes a first switch circuit disposed between a first node to which a positive electrode of a DC power supply is connected and a second node and a second switch circuit disposed between the second node and a third node. A first filter circuit includes a first capacitor. A bridge circuit includes a second leg and a third leg that are disposed in parallel between the first node and the third node. A clamp circuit includes a bidirectional switch disposed between a fourth node that is a midpoint of the second leg and a fifth node that is a midpoint of the third leg. A second filter circuit includes a first reactor and a second reactor.

Abstract: When an inverter and a converter are merely operated with their carrier waves synchronized with each other, current ripple of a smoothing capacitor connected therebetween might be increased. Accordingly, bipolar modulation PWM control is performed on the inverter, PWM control is performed on the converter, and the phase of the carrier wave for the inverter or the converter is shifted on the basis of AC output, whereby timings of currents flowing into the smoothing capacitor are made different from each other.

Abstract: When an inverter and a converter are merely operated with their carrier waves synchronized with each other, current ripple of a smoothing capacitor connected therebetween might be increased. Accordingly, bipolar modulation PWM control is performed on the inverter, PWM control is performed on the converter, and the phase of the carrier wave for the inverter or the converter is shifted on the basis of AC output, whereby timings of currents flowing into the smoothing capacitor are made different from each other.

Abstract: A reactor has one end connected to a neutral point of a transformer and the other end connected to a primary-side power supply. The transformer has almost no effective flux linkage for zero-phase current and has a phase difference between the primary side and the secondary side. A first bridge circuit and a second bridge circuit are connected to both ends of the transformer, and electric power of the primary-side power supply is controlled by the duty ratio of the first bridge circuit. The switching pattern of the second bridge circuit is phase-shifted in the leading direction and the lagging direction with reference to the switching pattern of the first bridge circuit, thereby achieving control such that soft switching operation can be performed even when the voltage ratio between the primary-side power supply and the secondary-side power supply fluctuates and the amount of transmission power is reduced.

Abstract: A power conversion device converts a direct-current power on the DC side of the power conversion device to an alternating-current power by an inverter circuit having a plurality of semiconductor switching elements, and outputs the AC power from the AC side of the power conversion device. A current detector detects a reactor current output from the inverter circuit. As overcurrent detector detects overcurrent in a control mode in which the reactor current is caused to follow a reactor current command value, control circuit starts an overcurrent mode in which a time period where the reactor current monotonically decreases is provided. In the overcurrent mode, whether to switch the overcurrent mode to the normal control mode is determined based on the reactor current or in accordance with a timing corresponding to a zero-cross point of a voltage or current on the AC side.

Abstract: A reactor has one end connected to a neutral point of a transformer and the other end connected to a primary-side power supply. The transformer has almost no effective flux linkage for zero-phase current and has a phase difference between the primary side and the secondary side. A first bridge circuit and a second bridge circuit are connected to both ends of the transformer, and electric power of the primary-side power supply is controlled by the duty ratio of the first bridge circuit. The switching pattern of the second bridge circuit is phase-shifted in the leading direction and the lagging direction with reference to the switching pattern of the first bridge circuit, thereby achieving control such that soft switching operation can be performed even when the voltage ratio between the primary-side power supply and the secondary-side power supply fluctuates and the amount of transmission power is reduced.