Abstract: The power conversion device includes a converter including a main switch element, a main rectifying element, an output capacitor, and a primary winding of a coupled inductor and a resonance assist circuit based on a closed-loop circuit including a first series circuit having a secondary winding of the coupled inductor, a first rectifying element, and an auxiliary switch element, a second series circuit having a tertiary winding of the coupled inductor and a second rectifying element, and an auxiliary capacitor to which the first series circuit and the second series circuit are connected. The secondary winding and the tertiary winding are separate bodies and the first series circuit and the second series circuit are connected in parallel to the auxiliary capacitor, or the tertiary winding is integrated with the secondary winding.

Abstract: An overvoltage protection circuit is provided which is connected between a rectifier circuit and a load including an input capacitor element connected to both ends of the load. The overvoltage protection circuit includes a semiconductor switch connected between the rectifier circuit and the load, and a control circuit controls the semiconductor switch. When the rectified voltage exceeds a predetermined value, the control circuit turns off the semiconductor switch, and detects a voltage potential difference between both ends of the semiconductor switch, and then, for an interval when the voltage potential difference is zero or a predetermined minute value, the control circuit generates a control voltage for turning on the semiconductor switch, and outputs the control voltage to a control terminal of the semiconductor switch. The overvoltage protection circuit includes a current change circuit that gradually changes a current flowing through the semiconductor switch.

Abstract: An overvoltage protection circuit is provided which is connected between a rectifier circuit and a load including an input capacitor element connected to both ends of the load. The overvoltage protection circuit includes a semiconductor switch connected between the rectifier circuit and the load, and a control circuit controls the semiconductor switch. When the rectified voltage exceeds a predetermined value, the control circuit turns off the semiconductor switch, and detects a voltage potential difference between both ends of the semiconductor switch, and then, for an interval when the voltage potential difference is zero or a predetermined minute value, the control circuit generates a control voltage for turning on the semiconductor switch, and outputs the control voltage to a control terminal of the semiconductor switch. The overvoltage protection circuit includes a current change circuit that gradually changes a current flowing through the semiconductor switch.

Abstract: In a power converter, switch-off of the synchronous rectification switch while the auxiliary switch is on causes the first capacitance of the main switch and the second capacitance of the synchronous rectification switch to resonate with the inductance of the second magnetic component. A parameter obtainer detects a voltage across a selected one of the main switch and the synchronous rectification switch, and obtains a parameter indicative of a corresponding one of rising and falling waveforms of the voltage across the selected switch while the selected switch is switched. A controller controls a switching control signal for the auxiliary switch to adjust switch-on timing of the auxiliary switch as a function of the parameter obtained by the parameter obtainer.

Abstract: In a power converter, a first electrical path connects between the series resonant circuit and a selected terminal from the high- and low-side input and output terminals of the power converter. An auxiliary diode is provided on one of the series resonant circuit and the first electrical path. An auxiliary switch, when turned on, causes an inductor current to flow through the auxiliary diode to the resonance inductor, thus storing electromagnetic energy into the resonance inductor, and causes the resonance inductor and the capacitance component of the series resonant circuit to resonate with each other. A second electrical path bypasses the auxiliary switch for flow of the inductor current. A discharge unit is provided on the second electrical path. The discharge unit is activated to discharge the electromagnetic energy stored in the resonance inductor via the second electrical path.

Abstract: In a power converter, a first electrical path connects between the series resonant circuit and a selected terminal from the high- and low-side input and output terminals of the power converter. An auxiliary diode is provided on one of the series resonant circuit and the first electrical path. An auxiliary switch, when turned on, causes an inductor current to flow through the auxiliary diode to the resonance inductor, thus storing electromagnetic energy into the resonance inductor, and causes the resonance inductor and the capacitance component of the series resonant circuit to resonate with each other. A second electrical path bypasses the auxiliary switch for flow of the inductor current. A discharge unit is provided on the second electrical path. The discharge unit is activated to discharge the electromagnetic energy stored in the resonance inductor via the second electrical path.

Abstract: In a power converter, switch-off of the synchronous rectification switch while the auxiliary switch is on causes the first capacitance of the main switch and the second capacitance of the synchronous rectification switch to resonate with the inductance of the second magnetic component. A parameter obtainer detects a voltage across a selected one of the main switch and the synchronous rectification switch, and obtains a parameter indicative of a corresponding one of rising and falling waveforms of the voltage across the selected switch while the selected switch is switched. A controller controls a switching control signal for the auxiliary switch to adjust switch-on timing of the auxiliary switch as a function of the parameter obtained by the parameter obtainer.

Abstract: When a commercial power supply E operates normally, converter sections PFC1, PFC2 connected in parallel to each other can operate to approximate the input current from the commercial power supply E to the waveform and phase of the input voltage to correct a power factor while supplying stabilized output voltages Vo1, Vo2 to a load. When the voltage of the commercial power supply E drops, the smoothing capacitor Co1 operates as an input power supply to power the converter section PFC2, which allows the smoothing capacitor Co2 to supply the stabilized output voltage Vo2 to the load.

Abstract: To provide a power supply apparatus that can supply a large current and a small current to a load circuit in a switchable manner, with a minimum circuit scale and an efficient use of electronic devices and elements contained in conventionally used power supply apparatuses.

Abstract: [OBJECT] A PFC converter is provided in which a smoothing capacitor can be small in size and a power supply circuit connected to the subsequent stages can be simple, efficient, low-cost, small in size and lightweight through the functionality of the PFC converter itself of preventing the output voltage from dropping in the event of a power failure or instantaneous power failure of an input power supply. [SOLUTION] When a commercial power supply E operates normally, converter sections PFC1, PFC2 connected in parallel to each other can operate to approximate the input current from the commercial power supply E to the waveform and phase of the input voltage to correct power factor while supplying stabilized output voltages Vo1, Vo2 to a load. On the other hand, when the voltage of the commercial power supply E drops, the smoothing capacitor Co1 operates as input power supply to power the converter section PFC2, which allows the smoothing capacitor Co2 to supply the stabilized output voltage Vo2 to the load.

Abstract: To provide a power supply apparatus that can supply a large current and a small current to a load circuit in a switchable manner, with a minimum circuit scale and an efficient use of electronic devices and elements contained in conventionally used power supply apparatuses.

Abstract: To eliminate the problem that a magnetic deflection is caused in a transformer even when a coupled inductor converter is in a stationary operation state, provided is a DC-DC converter including a first series circuit portion formed by a first switching transistor, a first capacitor, a first inductor, and a second capacitor which are connected to a DC power in series in this order, and a second series circuit portion formed by a second switching transistor and a second inductor which are connected in series in this order, the second series circuit portion is connected in parallel to the first capacitor and the first inductor, and the first inductor and the second inductor constitute a coupled inductor having a plurality of windings and a common magnetic core.

Abstract: The number of switches on the primary winding side of a transformer is decreased and ripples contained in the output voltage are greatly reduced. In a state I, Sia and Sib are switched ON, in a state II, Sim and Sia are switched ON, in a state III, Sia and Sib are switched ON, and in a state IV, Sim and Sib are switched ON. As a result, in the states I to III, a transformer Trsa is connected to a capacitor Ci, in the state IV, the transformer Trsa is connected to an input power source Vi supplying an electric current in the direction opposite to that of the capacitor Ci. Further, in states I, III, and IV, the transformer Trsb is connected to the capacitor Ci, and in state II, the transformer Trsb is connected to the input power source Vi supplying an electric current in the direction opposite to that of the capacitor Ci.

Abstract: The number of switches on the primary winding side of a transformer is decreased and ripples contained in the output voltage are greatly reduced. In a state I, Sia and Sib are switched ON, in a state II, Sim and Sia are switched ON, in a state III, Sia and Sib are switched ON, and in a state IV, Sim and Sib are switched ON. As a result, in the states I to III, a transformer Trsa is connected to a capacitor Ci, in the state IV, the transformer Trsa is connected to an input power source Vi supplying an electric current in the direction opposite to that of the capacitor Ci. Further, in states I, III, and IV, the transformer Trsb is connected to the capacitor Ci, and in state II, the transformer Trsb is connected to the input power source Vi supplying an electric current in the direction opposite to that of the capacitor Ci.