Abstract: In a voltage drop chopper type DC-DC converter, in an intermediate load area, a pulse train having a low peak value in the neighborhood of the threshold voltage is applied to a power MOSFET, whereby the power MOSFET is given a high ON resistance and turned on. By doing so, the output voltage is controlled by a PAM (pulse amplitude modulation) switch system for reducing the peak value below the supply voltage.

Abstract: A DC-DC converter is provided with a calculation circuit which estimates current flowing through a reactor in a control circuit for controlling a switching element and a circulation use element, and the switching element and the circulation use element are controlled by making use of the calculated reactor current value. Thereby, a DC-DC converter which operates in a high efficiency and with low ripple even during a light load condition and realizes a high response performance during load variation is provided.

Abstract: The efficiency of the DC-DC converter that the load factor varies greatly is improved.

Abstract: Disclosed is a parallel power source system which has a plurality of power supply units connected in parallel to one another and is designed in such a way that a voltage loss in an inverse-current preventing circuit provided in each power supply unit is reduced, the flexibility of the system design including lengths of power source wirings is maintained and when a short circuit failure occurs in some power supply unit, power supply from the other power supply units continues stably without significantly changing a voltage supplied to a load. The inverse-current preventing circuit comprises an MOS transistor that is intervened in series in an output path in each power supply unit and forms a switch circuit which is normally on, and a potential difference response circuit which operates to turn off the MOS transistor when a potential on the current-output side of the MOS transistor becomes greater than a potential on the current-input side thereof by at least a given amount.

Abstract: A power supply provided with: an AC/DC converter which receives AC power, converts the AC power into DC power, and outputs the DC power; a DC/DC converter which receives the DC power from the AC/DC converter, and controls a level of an output voltage of the DC/DC converter to be equal to a level of a voltage to be used by a load while the DC/DC converter supplies the output voltage to the load; a DC converter which is connected to an input of the DC/DC converter; and a DC power storage means which supplies electric power to the DC/DC converter through the DC converter.

Abstract: A DC power supply device comprises an AC/DC converter 1, a DC/DC converter 2, and a DC converter 3 converting DC power from a battery 4 to DC voltage for connecting to output terminals of the AC/DC converter. The DC power supply device is provided with a controlling circuit 100 which observes a charging control level and a load sharing level, impresses a charging command on a UPS controlling part controlling the DC converter, and simultaneously provides a PFC controlling part controlling the AC/DC converter with a current command when a voltage level is less than the charging control level, stops only the charging command when the voltage level is more than the charging level and less than the load sharing level, and provides the UPS controlling part and the PFC controlling part with current commands when the voltage level is more than the load sharing level.

Abstract: A power supply apparatus includes a semiconductor switching device for outputting power and a control circuit for controlling the on/off operation of the semiconductor switching device. The control circuit includes a circuit for applying, when turning on the semiconductor switching device, a first control signal corresponding to the difference between the output voltage of the power supply apparatus and a first reference value to the semiconductor switching device in accordance with the increase in the output voltage from the power supply apparatus thereby to operate the semiconductor switching device in a non-saturated area, so that the semiconductor switching device is turned on gradually.

Abstract: A direct-current power-supply apparatus provided by the present invention comprises a switching converter for converting an input direct-current power into another direct-current power, a control circuit and an isolation means. The switching converter has a main switch device for generating a pulse voltage from the direct-current input, a synchronous-rectification circuit on the output side of the switching converter and a reverse-current-blocking switch. On the other hand, the control circuit includes a PWM formation unit for driving the main switch device, a synchronous-rectification control unit for controlling an operation to drive the synchronous-rectification circuit and a driving control unit for controlling an operation to drive the reverse-current-blocking switch. The control circuit operates by using a common electric potential appearing on the output side of the switching converter as a reference electric potential. A driving signal is applied to the main switch device through the isolation means.

Abstract: A charge and discharge apparatus for electric power storage means has an AC power source, a transforming apparatus, which comprises a primary winding connected to the AC power source, and plural secondary windings, and plural electric power converters comprising plural AC sides, respective ones of which are connected to a respective one of the plural secondary windings, and plural DC sides, respective ones of which are connected to a respective one of the plural electric power storage means.

Abstract: In a uninterruptible power supply in which a plurality of inverters are operated in parallel, a current control loop is provided which responds to the magnitude of an output current of each inverter brought into parallel running to change a command value for a voltage waveform control circuit associated with each inverter, and the gain of the current control loop is made to be variable, whereby currents shared by the inverters can be set desirably to effectively suppress a cross current flowing between the inverters upon establishment of parallel running.

Abstract: A power supply control system including a variable power converter for converting electric power from a power supply to a load into that of a specification required by the load in response to a power specification information source provided on the load side. With a change in the load, the information source also changes, thereby providing a flexible power supply control system capable of meeting different loads. For applications to a high power supply, the system comprises a plurality of variable power converters adapted to operate selectively in accordance with requisite power information sources provided in or on the side of a plurality of loads, thereby providing a system realizing a flexible power supply. For application to a low power supply, the system comprises a plug having a power specification information source and a socket having a variable power converter.

Abstract: A three-phase a.c. uninterruptible power supply includes a transformer providing isolation between an input and an output, a single-phase inverter, and a cycloconverter. The uninterruptible power supply operates to convert a d.c. voltage into a high-frequency a.c. voltage in the single-phase inverter, transmit the output voltage of the single-phase inverter in an isolated state, and convert the output of the transformer into a three-phase voltage having a lower frequency, such as 50 or 60 Hz, than the frequency of the output voltage of the single-phase inverter. This enables the transformer providing isolation to operate at a high frequency, thereby enabling the size of the transformer to be reduced.

Abstract: In a module using a high-speed switching element such as an IGBT for a high-speed inverter, a matching condition is established between the switching characteristic of the IGBT and the recovery characteristic of the diode to be connected thereto in an anti-parallel fashion. As a result, the oscillating voltage appearing in the inverter circuit is suppressed to prevent erroneous operation of the inverter system.

Abstract: A structure is disclosed in which instantaneous phase and voltage difference values between the output voltage waveform from an inverter and the output voltage waveform from another AC power source are detected to correct the phase and the level of the output voltage waveform from the inverter so that the phase difference and the voltage difference can be controlled at high speed. As a result, excess current, which occurs if the inverter is operated at high frequencies, can be effectively controlled so that a stable parallel operation of the inverter with another AC power source is possible to perform.

Abstract: An ON holding circuit is provided which outputs a signal which identifies an ON state of an insulated gate transistor to a gate voltage input circuit, and inhibits the gate voltage input circuit from being responsive to an input signal which identifies an OFF state of the insulated gate transistor when an overcurrent adjusting circuit operates continuously.

Abstract: A mathematical model for simulating a dynamic characteristic of an electric power supply apparatus, a model control function for controlling an output from the mathematical model in a closed loop fashion and an electric power supply apparatus control function for approximating a control variable for the electric power supply apparatus to a reference value are provided in a control circuit, wherein an output from the mathematical model is output as a pulse width reference signal, and the pulse width reference signal is corrected by an on-delay portion due to switching elements by means of a gain revision circuit, thereby promptly and stably controlling the electric power supply apparatus.

Abstract: A switching power supply using a step-up transformer whose impedance viewed from its primary side is different from the impedance viewed from its secondary side whereby the inductance of its primary and secondary windings are settable independently of each other.

Abstract: In a power conversion system, a DC voltage of a DC power supply is converted into a predetermined high-frequency voltage by an inverter, and a high-frequency low voltage generated from the inverter is converted into a high-frequency high voltage by a transformer. A high-frequency high voltage generated from a secondary winding of the transformer is converted into a predetermined low-frequency voltage by a frequency changing circuit. The commutating operation of the frequency changing circuit is performed by a control circuit in response to the output current of the frequency changing circuit and in synchronism with the starting time of the short-circuiting prevention period of the inverter. As a result, the converted output of the power conversion system is prevented from decreasing.

Abstract: In a voltage resonance type switching power source apparatus, which has a step-up transformer, a resonance capacitor connected in series with a primary winding of the transformer, and a transistor connected in parallel with the capacitor to cause a resonant oscillation current by the on-off operation thereof, an on signal of the transistor is produced in synchronism with a second signal, which is obtained by delaying a first signal depending on a voltage induced in a detecting winding provided in the transformer by a predetermined delay time.

Abstract: A power conversion apparatus comprises an inverter for converting a voltage of a DC power source into AC power having a frequency higher than the commercial frequency, a transformer, fed by the inverter, for outputting AC power, which is adjusted at a desired voltage, a frequency converter, formed by two pairs of two gate turn-off thyristors (GTOs) connected in reverse-parallel, for converting the frequency of the AC power supplied from the transformer into the commercial frequency, and an energy regenerating device having capacitors for absorbing the energy of a spike voltage occurring due to a circuit inductance upon interruption of a current of each GTO of the frequency converter and a bridge circuit, formed by GTOs and diodes connected in reverse-paralel therewith, for switching over the direction of connecting the capacitors with a secondary winding of the transformer in accordance with the polarity of a voltage of the secondary winding in such a manner that the energy stored in the capacitors is regener