Abstract: In an uninterruptible power system with a battery pack (100) connected replaceably and conductively to a power control device (50) by a connector (104), the battery pack (100) and the power control device (50) are encased in a main box (10) having a battery pack load/unload opening (12). The battery pack load/unload opening (12) is adapted to be opened/closed by a protective cover (14). The opening of the protective cover (14) is detected by a protective cover opening detection switch (22) for detecting the opening of the protective cover (14). When opening of the protective cover (14) is detected by the protective cover opening detection switch (22) while the battery pack (100) is being charged or the backup power is being supplied by the battery pack (100) during a power failure, an internal switching circuit (60) of the power control device (50) is forcibly turned to a substantially open state or an alarm is output by an alarm buzzer (70).

Abstract: A power converter which can provide a power supply grounded on a positive electrode bus of a DC power supply without adding an additional power supply such as a switching regulator and reduce a circuit size and cost is described. When a switching device T1 of an upper arm is ON, the potential at point U is nearly equal to the potential at point P, and the current ic1 flows from the positive electrode of a first drive power supply 21 into a capacitor C1 via a diode D7 to charge the capacitor C1. A power supply Vc formed by the capacitor C1 can be used as a power supply grounded on a positive electrode bus P of the DC power supply.

Abstract: A power converting apparatus is obtained in which an integrated circuit for driving a power switching element is operated under stable conditions. A core 100 functioning as a common mode transformer made of a material such as ferrite is connected to a wiring line connected between a switch 7, a switch 8, and an IC 13 for opening/closing these switches 7 and 8 in a complementary manner, so that an impedance of a current path to the switch 7 and the IC 13 is increased.

Abstract: A control board includes a plate 7 for the control board including a first printed board for mounting a control section 56 and a first connecter 9; and a removable terminal stand plate 1 including a second printed board for mounting a terminal stand 3, input circuit section 4 and output circuit section 5, and a second connector. The first and second connectors are connected to each other.

Abstract: A power converting apparatus is comprised of an inverter unit arranged by a switching semiconductor element 51a for an upper arm and another switching semiconductor element 51d for a lower arm, and for turning ON/OFF the switching semiconductor elements to thereby convert DC power inputted from a DC power supply into AC power; and control means 10a for judging as to whether or not an abnormal operation is present based upon an output of a comparator 11a for judging as to whether or not a detection voltage detected by a voltage detecting circuit 61 is substantially equal to a voltage of the positive polarity; an output of a comparator 11b for judging as to whether or not a detection voltage detected by the voltage detecting circuit 61 is substantially equal to a voltage of the negative polarity; and an output signal of an igniting signal for ON/OFF-controlling the switching semiconductor elements, this voltage detecting circuit 61 detecting an output voltage of the inverter unit via a voltage dividing resistor

Abstract: A frequency converter device comprises a first converter 5 in a pulse-width modulation system for converting an AC voltage into a DC voltage; a second converter 2 in a pulse-width modulation system for supplying an AC voltage with a variable voltage and a variable frequency to a motor; a capacitor 15 connected between an output side of said first converter 5 and an input side of said second converter 15; a current suppressing circuit connected to the input side of said first converter 5 and consisting of a resistor 31 and a relay 32; a detection circuit 19 for detecting the presence or absence of the power supply inputted to said first converter 5; a circuit 16 for measuring the voltage across said capacitor 15; a drive control circuit 30a for stopping the conversion of said first converter 5 when power failure of an input power supply occurs and when the voltage across the capacitor is not smaller than a prescribed value, continuing the drive state of the relay 32 and said second converter 2, thereby continu

Abstract: A power supply apparatus has a switching device for converting a D.C. input to a high-frequency power; power conversion device for converting the high-frequency power into a plurality of D.C. output powers, a voltage maintaining device for sending a feedback signal to the switching device based on the value of one of the plurality of D.C. output powers thereby controlling the switching frequency and the duty ratio of the switching device in such a manner as to maintain the voltage of the one of the plurality of D.C. output powers constant, and a hysteresis device for varying the amount of the feedback in accordance with the load current on the D.C. output power used for the feedback so as to impart a predetermined hysteresis to the voltage change caused by a change in the load current.