An alternating current to direct current conversion circuit includes N first power converters instead of a boost circuit including a power switch with a high withstand voltage. The N first power converters each have an input end and theses input ends are connected in series, to perform power factor correction. Therefore, the alternating current to direct current conversion circuit includes no power switch with a high withstand voltage, so that the alternating current to direct current conversion circuit has a small volume, low switching loss, less energy loss, and good heat dissipation, thereby increasing power density.

A power converter circuit (1) and an associated method of converting an AC power supply. The power converter circuit (1) comprises: a supply rectifier circuit (2) for rectifying an AC supply power to generate a rectified supply power; an inverter circuit (3) for receiving the rectified supply power to generate an inverted supply power; a load rectifier circuit (4) for rectifying the inverted supply power to generate a rectified load power for supplying a load current to a load (5); and a charge pump circuit (6) driven by the load current to pump additional charge to the rectified supply power.

A power converter circuit (1) and an associated method of converting an AC power supply. The power converter circuit (1) comprises: a supply rectifier circuit (2) for rectifying an AC supply power to generate a rectified supply power; an inverter circuit (3) for receiving the rectified supply power to generate an inverted supply power; a load rectifier circuit (4) for rectifying the inverted supply power to generate a rectified load power for supplying a load current to a load (5); and a charge pump circuit (6) driven by the load current to pump additional charge to the rectified supply power.

The power conversion apparatus includes a converter circuit that converts an alternating-current voltage output from an alternating-current power supply into a direct-current voltage. The converter circuit includes unit converters. The power conversion apparatus includes current detectors that detect respective currents flowing through respective reactors. In first and second unit converters adjacent to each other among the unit converters, a phase difference between a first phase and a second phase is changed from a reference phase difference when a total current of currents detected by the respective current detectors is greater than a threshold. The first phase is a phase at a time when the switching element of the first unit converter is turned on. The second phase is a phase at a time when the switching element of the second unit converter is turned on.

In a switching power supply device, a control circuit controls a first thyristor, a second thyristor, and a switching element according to an input voltage. The control circuit maintains the first thyristor in an on state while maintaining the second thyristor and the switching element in an off state in a first period in which the absolute amplitude value is equal to or less than a first threshold value within the latter half of a first half-cycle of the input voltage at startup, and maintains the second thyristor in an on state while maintaining the first thyristor and the switching element in an off state in a second period in which the absolute amplitude value is equal to or less than a second threshold value within the latter half of a second half-cycle of the input voltage at startup. The second half-cycle is the half-cycle following the first half-cycle.

A power converting apparatus includes: a first arm including a switching element and a switching element connected in series; a second arm including a switching element and a switching element connected in series, the second arm being connected in parallel with the first arm; a reactor having one end connected to the switching element and the switching element and an opposite end connected to an alternating-current power supply; and a smoothing capacitor connected in parallel with the first arm and the second arm. The loss characteristic of the switching element and the second switching element that occurs in each switching event is better than the loss characteristic of the switching element and the switching element that occurs in each switching event.

A power converting apparatus includes: a first arm including a switching element and a switching element connected in series; a second arm including a switching element and a switching element connected in series, the second arm being connected in parallel with the first arm; a reactor having one end connected to the switching element and the switching element and an opposite end connected to an alternating-current power supply; and a smoothing capacitor connected in parallel with the first arm and the second arm. The loss characteristic of the switching element and the second switching element that occurs in each switching event is better than the loss characteristic of the switching element and the switching element that occurs in each switching event.

In a control apparatus for a power converter, a current obtainer obtains a current flowing through an inductor as an inductor current, and an alternating-current voltage obtainer obtains an alternating-current voltage. A drive signal outputting unit generates, based on the alternating-current voltage obtained by the voltage obtainer, a sinusoidal command. The drive signal outputting unit performs peak-current mode control to output a drive signal that controls switching of the drive switch to thereby cause the inductor current to follow the sinusoidal command. A delay unit delays, for one switching cycle of the drive switch, an off-switching timing of the drive switch in accordance with the alternating-current voltage. The drive signal defines the off-switching timing of the switch.

In a control apparatus for a power converter, a current obtainer obtains a current flowing through an inductor as an inductor current, and an alternating-current voltage obtainer obtains an alternating-current voltage. A drive signal outputting unit generates, based on the alternating-current voltage obtained by the voltage obtainer, a sinusoidal command. The drive signal outputting unit performs peak-current mode control to output a drive signal that controls switching of the drive switch to thereby cause the inductor current to follow the sinusoidal command. A delay unit delays, for one switching cycle of the drive switch, an off-switching timing of the drive switch in accordance with the alternating-current voltage. The drive signal defines the off-switching timing of the switch.

In the present uninterruptible power supply apparatus (U1), in a power failure of a commercial AC power supply (41), a switch (1) is turned off to electrically cut off the commercial AC power supply (41) from an AC input filter (2), and when DC voltage (ΔE=Ep−En) that is the difference between terminal-to-terminal voltages (Ep, En) of first and second capacitors (C1, C2) exceeds a threshold voltage (ETH), first and second IGBT devices (Q1, Q2) or third and fourth IGBT devices (Q3, Q4) included in the converter (3) are turned on and off to reduce DC voltage (ΔE).