Voltage step down type DC-DC converter having a coupled inductor
First Claim
1. A DC-DC buck converter comprising:
- a DC power supply, a main switch coupled to the DC power supply, a free-wheel inductor having first and second coils, one end of each of the coils being connected to a common junction, the other end of the first coil coupled to the main switch, wherein the free-wheel inductor includes an intermediate tap coupling the common junction to a free-wheel switch to provide that, when the free-wheel switch is ON, a free-wheeling current flows through said intermediate tap into the inductor, and wherein said free-wheel switch is an FET.
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Abstract
In the DC-DC converter according to the present invention, an intermediate tap is provided in the free-wheel inductor; the free-wheeling current goes out through the tap. The switch at the main switch side is driven by an N-channel FET (NPN transistor) and a pulse transformer, or the switch constitutes a P-channel FET (PNP transistor), so that the driving circuit at the rectifying side can be made simple. Further, the DC-DC converter includes loss-less snubber circuits or a soft switching circuit having a sub-switch in order to absorb and recover the surge energy from a leaked inductance, which is generated by the addition of the intermediate tap. Moreover, the driving circuit for the soft switching circuit is also simplified.
37 Citations
12 Claims
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1. A DC-DC buck converter comprising:
a DC power supply, a main switch coupled to the DC power supply, a free-wheel inductor having first and second coils, one end of each of the coils being connected to a common junction, the other end of the first coil coupled to the main switch, wherein the free-wheel inductor includes an intermediate tap coupling the common junction to a free-wheel switch to provide that, when the free-wheel switch is ON, a free-wheeling current flows through said intermediate tap into the inductor, and wherein said free-wheel switch is an FET. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A DC-DC voltage step down converter comprising:
a DC power supply, a main switch, a transformer having first and second primary coils and a third secondary coil, wherein one end of each of the first and second coils is connected to a common junction, an intermediate tap coupling the common junction to a main switch, a rectifying switch coupled to the third coil, a sub-switch for conducting a zero voltage transition operation coupled to the other end of the first coil via a diode, and wherein the rectifying switch is an FET. - View Dependent Claims (8, 9)
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10. A DC-DC buck converter assembly comprising:
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a plurality of DC-DC buck converters, wherein each of the converters includes a DC power supply, a main switch coupled to the DC power supply, a free-wheel inductor having first and second coils, one end of each of the coils being connected to a common junction, the other end of the first coil coupled to the main switch, wherein the free-wheel inductor includes an intermediate tap coupling the common junction to a free-wheel switch to provide that, when the free-wheel switch is ON, a free-wheeling current flows through said intermediate tap to the inductor, and wherein said free-wheel switch is an FET;
wherein the converters are connected together in parallel; and
a driver switch for switching the converters in a multiple-phased manner.
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11. A DC-DC voltage step down converter assembly comprising:
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a plurality of DC-DC buck converters, wherein each of the converters includes a DC power supply, a main switch, a transformer having first and second primary coils and a third secondary coil, wherein one end of each of the first and second coils is connected to a common junction, an intermediate tap coupling the common junction to a main switch, a rectifying switch coupled to the third coil, a sub-switch for conducting a zero voltage transition operation coupled to the other end of the first coil via a diode, and wherein the rectifying switch is an FET;
wherein the converters are connected together in parallel; and
a driver switch for switching the converters in a multiple-phased manner.
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12. A DC-DC buck converter comprising:
a DC power supply, a main switch coupled to the DC power supply, a free-wheel inductor having first and second coils which are arranged in parallel, one end of each of the coils being connected to a common junction, the other end of the first coil coupled to the main switch, and the other end of the second coil being connected to a free-wheel switch to provide that, when the free-wheel switch is ON, a free-wheeling current flows through said second coil into the inductor, and wherein said free-wheel switch is an FET.
Specification