A switching power-supply device applies a DC voltage to a primary winding of a transformer and performs a switching operation of a switching element connected to a primary winding to generate and output an output voltage to a load. The switching power-supply device includes: an error amplifier, which compares the output voltage with a reference voltage and sends an error voltage as a feedback signal to a primary side; a frequency generation circuit, which generates a switching frequency according to the feedback signal; an off timing determination circuit, which determines a timing at which the switching element is turned off, by comparing a signal depending on the feedback signal with a current flowing through the switching element; and a frequency correction circuit, which corrects the switching frequency generated by the frequency generation circuit, according to an on-duty of the switching element.

Disclosed is a high-voltage generator for an x-ray apparatus. The generator comprises a voltage multiplier having a high-voltage output terminal and first and second alternating-current input terminals, an output transformer coil (12) having first and second output terminals respectively electrically connected to the first and second input terminals of the voltage multiplier, and an input transformer coil (11) having first and second input terminals and being arranged coaxially with and inductively coupled to the output transformer coil. The input and output transformer coils are relatively axially movable. Disclosed is also an x-ray apparatus using the high-voltage generator, a method of configuring a high-voltage generator and a method of configuring a high-voltage apparatus.

A converter includes: a first transistor (Q1) connected between a first output terminal (T1) and an input terminal (T0); a second transistor (Q2) connected between the input terminal (T0) and a second output terminal (T2); first and second diodes (D1, D2) connected in anti-parallel to the first and second transistors (Q1, Q2), respectively; and a bidirectional switch that is connected between the input terminal (T0) and a third output terminal (T3) and that includes third and fourth transistors (Q3, Q4) and third and fourth diodes (D3, D4). The first and second diodes (D1, D2) and the third and fourth transistors (Q3, Q4) each are formed of a wide band gap semiconductor. The third and fourth diodes (D3, D4) and the first and second transistors (Q1, Q2) each are formed of a semiconductor other than the wide band gap semiconductor.

A converter includes: a first transistor (Q1) connected between a first output terminal (T1) and an input terminal (T0); a second transistor (Q2) connected between the input terminal (T0) and a second output terminal (T2); first and second diodes (D1, D2) connected in anti-parallel to the first and second transistors (Q1, Q2), respectively; and a bidirectional switch that is connected between the input terminal (T0) and a third output terminal (T3) and that includes third and fourth transistors (Q3, Q4) and third and fourth diodes (D3, D4). The first and second diodes (D1, D2) and the third and fourth transistors (Q3, Q4) each are formed of a wide band gap semiconductor. The third and fourth diodes (D3, D4) and the first and second transistors (Q1, Q2) each are formed of a semiconductor other than the wide band gap semiconductor.

A main circuit of a power conversion device includes: an AC/DC converter for performing power factor correction control for a single-phase AC power supply; and a DC/DC converter connected to the AC/DC converter via a DC capacitor. In order to reduce ripple voltage and ripple current for the DC capacitor, a control circuit superimposes, onto a DC current command, an AC current command having the minimum value at the zero cross phase of the single-phase AC power supply and having the maximum value at the peak phase thereof, to generate an output current command for the DC/DC converter, and performs output control for the DC/DC converter, using the output current command.

Disclosed is a power supply system, including: a high-voltage input power distribution cabinet, a high-low voltage conversion cabinet, and a low-voltage output and control cabinet, the high-low voltage conversion cabinet is provided with at least one high-voltage chamber provided with a high-voltage bus bar, at least one low-voltage chamber provided with a low-voltage bus bar, an insulating partition between the high-voltage chamber and the low-voltage chamber and a plurality of power supply modules; each of the power supply modules bridges the high-voltage and low-voltage chambers and includes a high-voltage cavity, a low-voltage cavity and an isolation unit, connecting terminals of the high-voltage and low-voltage cavities are respectively disposed corresponding to the high-voltage and low-voltage chambers and electrically connected to the high-voltage and low-voltage bus bars respectively, and the isolation unit is connected to one end of the high-voltage cavity and one end of the low-voltage cavity.

Disclosed is a rectifying circuit for high-frequency power supply that rectifies an alternating voltage at a high frequency equal to or higher than 2 MHz, the rectifying circuit for high-frequency power supply including a current doubler rectifier circuit that rectifies the alternating voltage inputted from a reception antenna for power transmission 10, a partial resonant circuit that causes the current doubler rectifier circuit to perform partial resonant switching in a switching operation at the time of rectification, a matching functional circuit that has a function of matching a resonance condition to that of the reception antenna for power transmission 10, and a function of matching the resonance condition to that of the partial resonant circuit, and a smoothing functional circuit that smooths the voltage rectified by the current doubler rectifier circuit into a direct voltage.

A power supply system which connects a DC consumer to an AC supply includes an AC-DC converter and a UPS. The AC-DC converter has an input to which alternating current from the AC supply is applied and an output at which DC current is developed. The UPS has an input to which direct current from the AC-DC converter is applied and an output at which DC current is developed. The DC current developed at the output of the AC-DC converter and DC current developed at the output of the UPS are applied to the DC consumer selectively in parallel with each other or exclusively to each other.

A power supply system which connects a DC consumer to an AC supply includes an AC-DC converter and a UPS. The AC-DC converter has an input to which alternating current from the AC supply is applied and an output at which DC current is developed. The UPS has an input to which direct current from the AC-DC converter is applied and an output at which DC current is developed. The DC current developed at the output of the AC-DC converter and DC current developed at the output of the UPS are applied to the DC consumer selectively in parallel with each other or exclusively to each other.

A power supply system which connects a DC consumer to an AC supply includes an AC-DC converter and a UPS. The AC-DC converter has an input to which alternating current from the AC supply is applied and an output at which DC current is developed. The UPS has an input to which direct current from the AC-DC converter is applied and an output at which DC current is developed. The DC current developed at the output of the AC-DC converter and DC current developed at the output of the UPS are applied to the DC consumer selectively in parallel with each other or exclusively to each other.