Matsushita Electric Works, Ltd.

Futoshi Okamoto

Hiroshi Kido

Koji Yamada

Hiroyuki Sako

Akinori Hiramatsu

Yukio Yamanaka

Masataka Mitani

An inverter device has a full-wave rectifier providing a pulsating DC voltage from an input AC voltage, a smoothing circuit. The smoothing circuit includes a choke coil, a smoothing capacitor and a switching element chopping the pulsating DC voltage through the choke coil into a smoothed DC voltage at the smoothing capacitor. An inverter is included to have the element common to the smoothing circuit and operating to switch the smoothed DC voltage to apply a resulting voltage to a load circuit including a load, inductance and capacitor. The inductance and capacitor define an oscillation circuit providing to the load an oscillating current composed of first and second currents of opposite directions. The oscillating current alternating to flow for a nominal on-time duration determined by a circuit constant of the oscillation circuit itself. A controller is included to detect the termination of the second current and excites the common switching element at a timing dependent upon the termination of the second current so as to start flowing the first current. The controller includes a timer for separately controlling an actual on-time duration for flowing the first current within the nominal on-time duration, whereby enabling to regulate the accumulated DC voltage in the smoothing capacitor at a desired level by controlling to vary the actual on-time duration of the common switching element.

Inverter device

A power source for providing a high frequency ac output voltage is provided with a rectifier, a smoothing circuit with an inductor and a smoothing capacitor, and an inverter having a switching device for switching the input dc voltage from the rectifier to provide a high frequency ac voltage output with reduced ripple. Also included in the smoothing circuit is a charge storage device by the operation of which the inductor receives electromagnetic energy from the current therein when the switching device is switched on and electromagnetic energy is fed to the smoothing capacitor to charge the same when the switching device is switched off, with the resulting voltage developed across the capacitor being applied to the inverter input. The charge storage device includes the inductor of the smoothing circuit and the switching device common to the inverter, such that the charge storage device is of the chopper-type which enables the inductor to be reduced to a smaller value while allowing it to retain a high power factor, and such that it can be readily incorporated in the power supply without requiring any additional switching devices and without undue increase in the component costs.

Power source

A power supply apparatus is structured such that the output of an alternating current voltage source (1) is connected to the input of a rectifying circuit (2), a series connection of a first smoothing capacitor (3a), a diode (15) and a second smoothing capacitor (3b) is connected to the output of the rectifying circuit so that the rectifying direction of the diodes may be opposite to the rectifying direction of the rectifying circuit, a first load (4a) is connected in parallel with the series connection portion of the first smoothing capacitor and the diode, and a second load (4b) is connected in parallel with the series connection portion of the second smoothing capacitor and the diode. Accordingly, during a period in which a ripple voltage of the output from the rectifying circuit is high, the first and second smoothing capacitors are charged and a current flows into the first and second loads, and during a period in which a ripple voltage of the output from the rectifying circuit is low a current flows from the first smoothing capacitor through the diode to the first load and a current flows from the second smoothing capacitor through the diode to the second load, whereby a stabilized voltage of little ripple component can be supplied to the first and second loads.

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Hirakata, Japan

Futoshi Okamoto