Abstract: [Problem] An object of the present invention is to provide a photovoltaic power generation system that performs the MPPT control with respect to respective panels and minimizes the power loss due to the power conversion. [Means for Solving the Problem] The photovoltaic power generation system according to the present invention performs an MPPT control for each photovoltaic panel by charging the lacking voltage or current. The power charge section connected in series or parallel to each panel charges the lacking voltage or current being caused by the non-uniformity of light quantities of the photovoltaic panels or temperatures.

Abstract: A processing speed may be easily controlled over the wide range within the impedance variation range.

Abstract: In an induction motor group control system, magnetic energy recovery switches (3) are connected in series to an induction motor (2) directly driven by a commercial power supply, and a plurality of induction motor control devices (10) enabling voltage control and reactive power control of the induction motor 2 are employed to control generation of reactive power so as to maximize a power factor of the entire plurality of AC loads including the induction motor or compensate variations in voltage of an AC power supply (1).

Abstract: The alternating voltage control apparatus which is inserted serially between an alternating-current power source and an inductive load and which controls adjustment of load voltage of the inductive load with a magnetic energy recovery switch reduces a voltage burden of a reverse conduction type semiconductor switch within the magnetic energy recovery switch and a capacitor and controls voltage to be supplied to the inductive load with a small advancing amount of a phase of current to be supplied to the inductive load.

Abstract: This invention provides a steel pipe material weld zone heating method and apparatus for melting and welding the weld zone of a steel pipe material that during continuous induction heating and welding of moving steel pipe material as the material being heated controls temperature distribution and molten steel shape and weld frequency fluctuation with high accuracy and high efficiency, irrespective of the shape of the heated region of material being heated or the material properties of the material being heated, which comprises a first imaging device, a weld zone temperature distribution computation device, a heating control device, and a variable frequency alternating current power supply device.

Abstract: A power conversion device (1) comprises an inductor (L) serried-connected to an alternating-current power source (20) and a load (30), a full-bridge MERS (100) parallel-connected to the load (30), a control circuit (110), a current direction switching part (200) serried-connected between the inductor (L) and load (30), and an ammeter (300). The control circuit (110) feeds back the current detected by the ammeter (300), repeatedly turns on/off either a pair of reverse conductive semiconductor switches (SW2, SW3) or a pair of reverse conductive semiconductor switches (SW1, SW4) constituting the full-bridge MERS (100), which corresponds to the positive/negative voltage output from the alternating-current source (20), and keeps the other pair being off.

Abstract: A power inverter (1) is provided with a full-bridge circuit (10), a shunt capacitor (CP), and a control circuit (20). The control circuit (20) controls the on/off state of each reverse-conductive semiconductor switch (SW1 to SW4) at a switching frequency of not more than the resonance frequency determined by the capacitance of the shunt capacitor (CP) and the inductance of an inductive load (LD) in such a matter than when a first reverse-conductive semiconductor switch (SW1) and a fourth reverse-conductive semiconductor switch (SW4) are in the on-state, a second reverse-conductive semiconductor switch (SW2) and a third reverse-conductive semiconductor switch (SW3) are brought into the off-state, and that when the first reverse-conductive semiconductor switch (SW1) and the fourth reverse-conductive semiconductor switch (SW4) are in the off-state, the second reverse-conductive semiconductor switch (SW2) and the third reverse-conductive semiconductor switch (SW3) are brought into the on-state.

Abstract: In an induction motor group control system, magnetic energy recovery switches (3) are connected in series to an induction motor (2) directly driven by a commercial power supply, and a plurality of induction motor control devices (10) enabling voltage control and reactive power control of the induction motor 2 are employed to control generation of reactive power so as to maximize a power factor of the entire plurality of AC loads including the induction motor or compensate variations in voltage of an AC power supply (1).

Abstract: An AC/DC power converter which charges a secondary battery from an AC power supply and also converts power from the secondary battery to the AC voltage is provided. A capacitor C is connected to DC terminals of the four reverse-conductive type semiconductor switches in a single-phase bridge structure, and a secondary battery is connected via a DC inductance to the semiconductor switches. The semiconductor switches are connected via an AC inductance L with an AC power supply and opposing pairs of the semiconductor switches are alternately turned ON/OFF in synchronization with the phase of the supply voltage. When an AC power supply with a frequency which is lower than the resonance frequency of the LC is connected, the switching will be carried out in a zero-voltage-zero-current condition and AC/DC reversible power conversion is possible just through the control of the gate phase of the switches.

Abstract: In order to protect Magnetic Energy Recovery Switch (MERS) against an overvoltage and an overcurrent a voltage detection unit is provided for detecting the capacitor voltage of the MERS and control means is provided to control so as to turn ON the switch of the discharge circuit connected in parallel with the capacitor to make the capacitor discharge the electric charge thereof when the output of the voltage detection unit exceeds a predetermined value. Moreover, a current detection unit is interposed between the AC power supply and the load for detecting the current flowing to the load, and the current limiting is carried out by making the duty ratio of the ON/OFF of the pulse of the gate control signals of the MERS switches smaller than 0.5, when the output of the current detection unit exceeds a predetermined value.

Abstract: A processing speed may be easily controlled over the wide range within the impedance variation range.

Abstract: Provided is an AC voltage control device for adjusting the voltage of a load to be connected with an AC power source, by a convenient method. In this AC voltage control device, a magnetic energy recovery switch including a capacitor and an AC switch circuit connected in parallel is connected between the AC power source and the load. The AC switch circuit is turned on several ms from such a timing of a zero capacitor voltage as occurs twice for one current cycle, so that a capacitor current is bypassed to reduce a reactance voltage thereby to adjust the voltage of the load.

Abstract: Reverse conducting type semiconductor switches are arranged in a bride from, an energy storage capacitor is connected with its DC terminal to obtain a magnetic energy regeneration switch, and then an induction coil is connected to its AC terminal. An AC pulse current of variable frequency is obtained by applying a gate signal to the semiconductor switch to thereby turn it ON/OFF; since a voltage is generated automatically by regenerating magnetic energy, a DC power supply is connected to the opposite ends of the capacitor through a smoothing coil, thus injecting power.

Abstract: The alternating voltage control apparatus which is inserted serially between an alternating-current power source and an inductive load and which controls adjustment of load voltage of the inductive load with a magnetic energy recovery switch reduces a voltage burden of a reverse conduction type semiconductor switch within the magnetic energy recovery switch and a capacitor and controls voltage to be supplied to the inductive load with a small advancing amount of a phase of current to be supplied to the inductive load.

Abstract: The present invention provides a PM motor drive power supply apparatus which drives a three-phase permanent-magnet synchronous motor by utilizing a direct-current power source 1, wherein control means 7 controls to simultaneously perform ON/OFF operation of a diagonally positioned pair among reverse conductive semiconductor switches (S1 to S4) of pulse voltage generating means 2, controls to perform ON/OFF operation of switches of three lines of polarity switching means 5 in turns at the same timing as the reverse conductive semiconductor switches (S1 to S4) of the pulse voltage generating means 2, selects a switch of the polarity switching means 5 based on the rotational position signal, converts direct-current pulse output of the pulse voltage generating means 2 into polarities of the three-phase alternating-current, and supplies to a PM motor 4 as drive current.

Abstract: In order to provide a pulse power supply device using regenerating magnetic energy stored in a discharge circuit to a capacitor so as to use it as next discharge energy and supplying a bipolar pulse current with high repetition, a bridge circuit is composed of four inverse-conductive semiconductor switches, a charged energy source capacitor is connected to a DC terminal of the bridge circuit, and an inductive load is connected to its AC terminal. A control signal is supplied to gates of the inverse-conductive semiconductor switches, and a control is made so that when a discharge current rises, is maintained, or is reduced, all the gates are turned off, and the magnetic energy of the electric current can be automatically regenerated to the energy source capacitor by a diode function of the switches. Further, a large current power supply is inserted into a discharge circuit so as to replenish energy loss due to discharge, thereby enabling high-repetition discharge.

Abstract: In order to provide a pulse power supply device using regenerating magnetic energy stored in a discharge circuit to a capacitor so as to use it as next discharge energy and supplying a bipolar pulse current with high repetition, a bridge circuit is composed of four inverse-conductive semiconductor switches, a charged energy source capacitor is connected to a DC terminal of the bridge circuit, and an inductive load is connected to its AC terminal. A control signal is supplied to gates of the inverse-conductive semiconductor switches, and a control is made so that when a discharge current rises, is maintained or is reduced, all the gates are turned off, and the magnetic energy of the electric current can be automatically regenerated to the energy source capacitor by a diode function of the switches. Further, a large-current power supply is inserted into a discharge circuit so as to replenish energy loss due to discharge, thereby enabling high-repetition discharge.

Abstract: In order to protect Magnetic Energy Recovery Switch (MERS) against an overvoltage and an overcurrent a voltage detection unit is provided for detecting the capacitor voltage of the MERS and control means is provided to control so as to turn ON the switch of the discharge circuit connected in parallel with the capacitor to make the capacitor discharge the electric charge thereof when the output of the voltage detection unit exceeds a predetermined value. Moreover, a current detection unit is interposed between the AC power supply and the load for detecting the current flowing to the load, and the current limiting is carried out by making the duty ratio of the ON/OFF of the pulse of the gate control signals of the MERS switches smaller than 0.5, when the output of the current detection unit exceeds a predetermined value.

Abstract: The present invention relates to an alternating-current power supply device which can improve a power factor of an alternating-current load, realizes low cost and miniaturization, and recovers magnetic energy. The alternating-current power supply device includes a bridge circuit composed of four reverse conducting semiconductor switches, a capacitor that is connected between direct-current terminals of the bridge circuit and absorbs the magnetic energy at the time of cutting off the current, an alternating-current voltage source that is connected to the induction load in series and is inserted between alternating-current terminals of the bridge circuit, and a control circuit that gives a control signal to gates of the respective reverse conducting semiconductor switches and controls on/off states of the respective reverse conducting semiconductor switches.

Abstract: In order to provide a pulse power supply device using regenerating magnetic energy stored in a discharge circuit to a capacitor so as to use it as next discharge energy and supplying a bipolar pulse current with high repetition, a bridge circuit is composed of four inverse-conductive semiconductor switches, a charged energy source capacitor is connected to a DC terminal of the bridge circuit, and an inductive load is connected to its AC terminal. A control signal is supplied to gates of the inverse-conductive semiconductor switches, and a control is made so that when a discharge current rises, is maintained or is reduced, all the gates are turned off, and the magnetic energy of the electric current can be automatically regenerated to the energy source capacitor by a diode function of the switches. Further, a large-current power supply is inserted into a discharge circuit so as to replenish energy loss due to discharge, thereby enabling high-repetition discharge.