Abstract: A power conversion device includes a power conversion circuit that performs switching control of first and second semiconductor switches connected in series and converts an input direct current voltage into an alternating current voltage. A switching adjustment circuit includes a first capacitance addition circuit that increases an output capacitance of the first semiconductor switch. The first capacitance addition circuit includes a first capacitive element and a first switching unit connected in series and is connected in parallel to the first semiconductor switch. A first driving control circuit drives and controls the first capacitance addition circuit. The first driving control circuit turns on the first switching unit when the first semiconductor switch is turned off, increasing the output capacitance of the first semiconductor switch, and turns off the first switching unit when a predetermined time period elapses after the first semiconductor switch is turned off.

Abstract: A power conversion device includes a power conversion circuit that performs switching control of first and second semiconductor switches connected in series and converts an input direct current voltage into an alternating current voltage. A switching adjustment circuit includes a first capacitance addition circuit that increases an output capacitance of the first semiconductor switch. The first capacitance addition circuit includes a first capacitive element and a first switching unit connected in series and is connected in parallel to the first semiconductor switch. A first driving control circuit drives and controls the first capacitance addition circuit. The first driving control circuit turns on the first switching unit when the first semiconductor switch is turned off, increasing the output capacitance of the first semiconductor switch, and turns off the first switching unit when a predetermined time period elapses after the first semiconductor switch is turned off.

Abstract: A DC-DC converter includes a filter circuit, a full-bridge circuit connected to the filter circuit, and a transformer having a primary winding and a secondary winding, the primary winding being connected to the full-bridge circuit. The full-bridge circuit includes first to fourth semiconductor switches. First to fourth overvoltage protection circuits are associated with the first to fourth semiconductor switches, respectively. Each of the overvoltage protection circuits is connected in parallel its associated semiconductor switch.

Abstract: A DC-DC converter includes a filter circuit, a full-bridge circuit connected to the filter circuit, and a transformer having a primary winding and a secondary winding, the primary winding being connected to the full-bridge circuit. The full-bridge circuit includes first to fourth semiconductor switches. First to fourth overvoltage protection circuits are associated with the first to fourth semiconductor switches, respectively. Each of the overvoltage protection circuits is connected in parallel its associated semiconductor switch.

Abstract: A three-level inverter circuit includes first to fourth front-stage switches connected in series, and a floating capacitor connected between a connection point of the first and second front-stage switches and a connection point of the third and fourth front-stage switch elements, and outputs an intermediate voltage of a DC power supply through a connection point of the second and third front-stage switches. A bridge circuit includes first, second, third, and fourth rear-stage switches which are bridge-connected to first to fourth terminals. The first terminal thereof is connected to a connection point of the second front-stage switch and the third front-stage switch and a second terminal thereof is connected to the second input terminal.

Abstract: A power supply device is provided for a vehicle having an idling-stop function, the power supply device including a boosting converter circuit with small loss that compensates for a voltage drop of a battery during starting of the engine and performing a protection function against a case in which the polarities of the battery are mistakenly connected in reverse. A series circuit including two MOSFETs serially connected to one another and an inductor is connected to the ends of a DC power source. A diode is connected to the connection point between the two MOSFETS serially connected to one another and the inductor, and a capacitor is connected in parallel to the two MOSFETS serially connected to one another. The two MOSFETs are serially connected such that the polarities of respective body diodes thereof are opposite to each other.

Abstract: A three-level inverter circuit includes first to fourth front-stage switches connected in series, and a floating capacitor connected between a connection point of the first and second front-stage switches and a connection point of the third and fourth front-stage switch elements, and outputs an intermediate voltage of a DC power supply through a connection point of the second and third front-stage switches. A bridge circuit includes first, second, third, and fourth rear-stage switches which are bridge-connected to first to fourth terminals. The first terminal thereof is connected to a connection point of the second front-stage switch and the third front-stage switch and a second terminal thereof is connected to the second input terminal.

Abstract: In an inverter apparatus, an output voltage of an active filter circuit that steps up and smoothes a DC voltage is converted into an AC voltage by an inverter circuit. The active filter circuit includes a capacitor and a rectifier device connected between an input node and an output node. An inductor, one end of which is connected to the input node and the other end of which is connected the output node through the rectifier device, and a switch device connected between the other end and a low-potential-side line, and a first control circuit for the switch device are provided. The inductor stores energy while the switch device is on and releases the energy while the switch device is off. The rectifier device conducts such that the stored energy of the inductor is released.

Abstract: In an inverter apparatus, an output voltage of an active filter circuit that steps up and smoothes a DC voltage is converted into an AC voltage by an inverter circuit. The active filter circuit includes a capacitor and a rectifier device connected between an input node and an output node. An inductor, one end of which is connected to the input node and the other end of which is connected the output node through the rectifier device, and a switch device connected between the other end and a low-potential-side line, and a first control circuit for the switch device are provided. The inductor stores energy while the switch device is on and releases the energy while the switch device is off. The rectifier device conducts such that the stored energy of the inductor is released.

Abstract: A processor includes analog signal input ports, an A/D conversion unit, and an ALU in a stage subsequent to the A/D conversion unit, separately from a CPU. The ALU not only stores a comparison result in a RAM independently of the CPU, but also compares an output value of the A/D conversion unit with a reference value set in the RAM, and interrupts the CPU or issues a command to a PWM generator in accordance with a flag based on the comparison result. This realizes high-speed processing in accordance with a change in an analog signal, although the processor has a low cost and a low clock frequency overall.

Abstract: A power supply device is provided for a vehicle having an idling-stop function, the power supply device including a boosting converter circuit with small loss that compensates for a voltage drop of a battery during starting of the engine and performing a protection function against a case in which the polarities of the battery are mistakenly connected in reverse. A series circuit including two MOSFETs serially connected to one another and an inductor is connected to the ends of a DC power source. A diode is connected to the connection point between the two MOSFETS serially connected to one another and the inductor, and a capacitor is connected in parallel to the two MOSFETS serially connected to one another. The two MOSFETs are serially connected such that the polarities of respective body diodes thereof are opposite to each other.

Abstract: A DC-DC converter includes an inductor, a capacitor, an output voltage detection circuit, and a synchronous rectification circuit including a rectifier-side synchronous rectifier element and a commutator-side synchronous rectifier element. The commutator-side synchronous rectifier element is turned on so as to pass a current through a closed loop composed of the commutator-side synchronous rectifier element, the inductor, and a second secondary battery. The characteristic evaluation of the second secondary battery is performed on the basis of the decrease in a detection voltage Vout of an output voltage Vo. As a result, it is possible to determine the effective capacity or characteristic degradation state of the second secondary battery with a circuit to charge the second secondary battery without using a dedicated circuit.

Abstract: A switching power supply apparatus includes a transformer or an inductor, a switching element connected to the transformer or the inductor and configured to perform switching of an input power supply, and a switching control circuit including a digital control circuit configured to sample voltage values and/or current values and control on and off of the switching element in accordance with the voltage values and/or current values. The number of points of sampling is set to n or more points, where n is an integer greater than 3, in an ON period of the switching element except at around a turn-on point or a turn-off point of the switching element. The presence or absence of magnetic saturation of the transformer or the inductor is detected on the basis of whether or not a slope of change in current value over time is larger than a predetermined value, and circuit operation is protected from the effect of magnetic saturation.

Abstract: A DC-DC converter includes an inductor, a capacitor, an output voltage detection circuit, and a synchronous rectification circuit including a rectifier-side synchronous rectifier element and a commutator-side synchronous rectifier element. The commutator-side synchronous rectifier element is turned on so as to pass a current through a closed loop composed of the commutator-side synchronous rectifier element, the inductor, and a second secondary battery. The characteristic evaluation of the second secondary battery is performed on the basis of the decrease in a detection voltage Vout of an output voltage Vo. As a result, it is possible to determine the effective capacity or characteristic degradation state of the second secondary battery with a circuit to charge the second secondary battery without using a dedicated circuit.

Abstract: A switching circuit arranged to switch the input of an input power supply is connected to a primary winding of a transformer at a primary side of the transformer. A digital control circuit including a switching controller arranged to output control pulses to the switching circuit and a rectifying/smoothing circuit connected to secondary windings of the transformer are disposed at a secondary side of the transformer. The digital control circuit outputs the control pulses via a pulse transformer, calculates the input power-supply voltage on the basis of the on-duty cycle of the control pulses, the output voltage, and the ratio of the number of turns of the primary winding to the number of turns of the secondary windings of the transformer, and performs converter control in accordance with the calculated input power-supply voltage.

Abstract: A processor includes analog signal input ports, an A/D conversion unit, and an ALU in a stage subsequent to the A/D conversion unit, separately from a CPU. The ALU not only stores a comparison result in a RAM independently of the CPU, but also compares an output value of the A/D conversion unit with a reference value set in the RAM, and interrupts the CPU or issues a command to a PWM generator in accordance with a flag based on the comparison result. This realizes high-speed processing in accordance with a change in an analog signal, although the processor has a low cost and a low clock frequency overall.

Abstract: A switching power supply apparatus includes a transformer or an inductor, a switching element connected to the transformer or the inductor and configured to perform switching of an input power supply, and a switching control circuit including a digital control circuit configured to sample voltage values and/or current values and control on and off of the switching element in accordance with the voltage values and/or current values. The number of points of sampling is set to n or more points, where n is an integer greater than 3, in an ON period of the switching element except at around a turn-on point or a turn-off point of the switching element. The presence or absence of magnetic saturation of the transformer or the inductor is detected on the basis of whether or not a slope of change in current value over time is larger than a predetermined value, and circuit operation is protected from the effect of magnetic saturation.

Abstract: A switching circuit arranged to switch the input of an input power supply is connected to a primary winding of a transformer at a primary side of the transformer. A digital control circuit including a switching controller arranged to output control pulses to the switching circuit and a rectifying/smoothing circuit connected to secondary windings of the transformer are disposed at a secondary side of the transformer. The digital control circuit outputs the control pulses via a pulse transformer, calculates the input power-supply voltage on the basis of the on-duty cycle of the control pulses, the output voltage, and the ratio of the number of turns of the primary winding to the number of turns of the secondary windings of the transformer, and performs converter control in accordance with the calculated input power-supply voltage.

Abstract: A DC-DC converter includes a resonant coil (Lr) for zero voltage switching, the resonant coil being connected in series to a primary winding (Np), and a full-bridge switching circuit driven by phase shift control. The DC-DC converter includes a first regenerative diode (D7) disposed between a connection between the primary winding (Np) and the resonant coil (Lr) and a first terminal of an input power supply (Vin) and a second regenerative diode (D8) disposed between the connection and a second terminal of the input power supply (Vin). This structure enables a surge resulting from a reverse recovery current in rectifier diodes (D1, D2) at the secondary side to be regenerated to the input power supply via the regenerative diodes (D7, D8), thus reducing a surge voltage applied to the rectifier diodes (D1, D2). As a result, a rectifier diode that has a low breakdown voltage and a small forward voltage drop can be used. The loss caused by a forward current in the rectifier diodes can be reduced.

Abstract: Conventionally, a non-conductive period is provided in a region in the vicinity of zero of an AC power voltage via a voltage detection circuit 14 to turn off reliably. The FET 17 maintains the ON state within several switching cycles after the non-conductive interval to rapidly restore the magnetizing coil current, so that the magnetizing coil current rapidly increases. An object is to suppress beat noise in the electromagnetic device. Within a prescribed interval following the non-conductive interval, a partial voltage at a resistor 19 of an output V2 of a mono-stable circuit 20 is added as a bias voltage to a detection voltage of a magnetizing coil current at a resistor 18, and is detected by the IC 11. The IC 11 drives a FET 17 with a constant switching period after the non-conductive interval, thereby preventing the increase in the magnetizing coil current and resolving the problem.