US 2008/0291702 A1Published application

Switching power supply apparatus

AssigneeMurata Manufacturing Co., Ltd.

InventorTatsuya HOSOTANI

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Abstract

In a switching power supply apparatus, an inductor, a transformer, a first switching circuit, a second switching circuit, and a capacitor are connected to each other so that a first switching element and a second switching element can be alternately turned on and off, an output can be obtained from a secondary winding of the transformer, and an output voltage can be controlled by controlling the ON period of the first switching element. The secondary winding of the transformer is connected to a first rectifying and smoothing circuit. A first control circuit is configured to operate using a DC voltage supplied from a second rectifying and smoothing circuit. After the second switching element has been turned on, the second switching element is forcefully turned off at a predetermined time set by a turn-off circuit included in a second control circuit that operates using an AC voltage.

Claims24

Dependent claims

A switching power supply apparatus comprising:

a first switching circuit including a parallel connection circuit that includes a first switching element, a first diode, and a first capacitor;
a second switching circuit including a parallel connection circuit that includes a second switching element, a second diode, and a second capacitor;
a first control circuit configured to operate using a direct current and control ON and OFF of the first switching element;
a second control circuit configured to control ON and OFF of the second switching element, the second control circuit including a turn-off circuit;
and
a transformer including a primary winding, a secondary winding, a first driving winding, and a second driving winding, the secondary winding being connected to a first rectifying and smoothing circuit, the first and second driving windings each generating a voltage substantially proportional to a voltage of the primary winding, the first driving winding being connected to the first control circuit via a second rectifying and smoothing circuit, the second driving winding being connected to the second control circuit;
wherein
a power input portion, an inductor, the primary winding of the transformer, at least one capacitor, and the first switching circuit define a series circuit, and a series circuit including the inductor, the primary winding of the transformer, and the at least one capacitor is connected in parallel to the second switching circuit;
or
the power input portion, the inductor, the primary winding of the transformer, and the first switching circuit define a series circuit, and a series circuit including the inductor and the primary winding of the transformer is connected in parallel to a series circuit including the second switching circuit and at least one capacitor;
or
the power input portion, the inductor, the primary winding of the transformer, and the first switching circuit define a series circuit, and a series circuit including the second switching circuit and at least one capacitor is connected in parallel to the first switching circuit;
and
an output voltage is controlled by controlling an ON period of the first switching element, and the second switching element is forcefully turned off after a predetermined time set by the turn-off circuit has elapsed since the second control circuit, operated using an alternating voltage generated by the second driving winding, turned the second switching element on.

11 more elements

A switching power supply apparatus comprising:

a first switching circuit including a parallel connection circuit that includes a first switching element, a first diode, and a first capacitor;
a second switching circuit including a parallel connection circuit that includes a second switching element, a second diode, and a second capacitor;
a first control circuit configured to operate using a direct current and control ON and OFF of the first switching element;
a second control circuit configured to control ON and OFF of the second switching element, the second control circuit including a turn-off circuit;
and
a transformer including a primary winding, a secondary winding, a first driving winding, and a second driving winding, the secondary winding being connected to a first rectifying and smoothing circuit, the first and second driving windings each generating a voltage substantially proportional to a voltage of the primary winding, the first driving winding being connected to the first control circuit via a second rectifying and smoothing circuit, one end of the second driving winding being connected to one end of the second switching circuit, the other end of the second driving winding being connected to the second control circuit;
wherein
a power input portion, an inductor, the primary winding of the transformer, at least one capacitor, and the second switching circuit define a series circuit, and a series circuit including the inductor, the primary winding of the transformer, and the at least one capacitor is connected in parallel to the first switching circuit;
or
the power input portion, the inductor, the primary winding of the transformer, and the second switching circuit define a series circuit, and a series circuit including the inductor and the primary winding of the transformer is connected in parallel to a series circuit including the first switching circuit and at least one capacitor;
or
the power input portion, the inductor, the primary winding of the transformer, and the second switching circuit define a series circuit, and a series circuit including the first switching circuit and at least one capacitor is connected in parallel to the second switching circuit;
and
an output voltage is controlled by controlling an ON period of the second switching element, and the second switching element is forcefully turned off after a predetermined time set by the turn-off circuit has elapsed since the second control circuit, operated using an alternating voltage generated by the second driving winding, turned the second switching element on.

11 more elements

Dependencies are inferred from the claim text.