Resonant converter capable of adaptively tuning quality factor based on load
Provided is a resonant converter capable of adaptively tuning a quality factor based on load. The resonant converter includes a resonant tank having an inductor part whose inductance is tunable according to a first control potential, a magnetizing inductor, and a capacitor part whose capacitance is tunable according to a second control potential. The resonant converter detects the rectifying current of its output stage for responding to the load state of the resonant converter. The resonant converter outputs the first and second control potentials in response to the load state, tuning the equivalent inductance of the inductor part, the equivalent capacitance of the capacitor part, or both, thereby changing the quality factor of the resonant converter.
1 . A resonant converter capable of adaptively tuning a quality factor based on a load, comprising:
a power switch circuit, receiving an input direct-current (DC) potential for generating a switching potential;
a resonant tank, receiving the switching potential, including:
an inductor part, having an inductance tuned according to a first control potential;
a magnetizing inductor; and
a capacitor part, having a capacitance tuned according to a second control potential;
a transformer, including a primary winding and a first secondary winding, wherein the primary winding is coupled to the magnetizing inductor;
an output stage, coupled to a first terminal and a second terminal of the transformer, which includes a rectifying device, a detecting resistor, and an output capacitor;
an averaging circuit, coupled to a first terminal and a second terminal of the detecting resistor, for obtaining and outputting an average potential, wherein the average potential corresponds to an average current flowing through the rectifying device; and
a controller, receiving the average potential, and outputting the first control potential and the second control potential;
wherein the inductor part, the magnetizing inductor, and the capacitor part are connected in series, and arranged together between a first node and a first reference ground;
the first node is coupled to the switching potential;
the inductor part includes a resonant inductor, at least one auxiliary inductor, and a first auxiliary switch set;
the capacitor part includes a resonant capacitor, at least one auxiliary capacitor, and a second auxiliary switch set;
wherein the first auxiliary switch set changes the connecting configuration of the resonant inductor and the auxiliary inductor according to the first control potential;
wherein the second auxiliary switch set changes the connecting configuration of the resonant capacitor and the auxiliary capacitor according to the second control potential;
wherein the transformer further includes a second secondary winding;
the rectifying device includes a first rectifying component and a second rectifying component;
the first secondary winding and the second secondary winding both have a first terminal and a second terminal;
a first terminal and a second terminal of the first rectifying component are respectively coupled to the first terminal of the first secondary winding and the first terminal of the detecting resistor;
a first terminal and a second terminal of the second rectifying component are respectively coupled to the second terminal of the second secondary winding and the first terminal of the detecting resistor;
the second terminal of the first secondary winding is coupled to the first terminal of the second secondary winding and a second reference ground; and
the output capacitor has a first terminal and a second terminal, the first terminal of the output capacitor is coupled to the second terminal of the detecting resistor, and the second terminal of the output capacitor is coupled to the second reference ground.
2 . The resonant converter as claimed in claim 1 , wherein
the resonant inductor is coupled to the first node and a second node;
the first auxiliary switch set includes a first switch, which is connected in series with the auxiliary inductor, and is arranged together with the auxiliary inductor between the first node and the second node;
the resonant capacitor is coupled to a third node and the first reference ground;
the second auxiliary switch set includes a second switch, which is connected in series with the auxiliary capacitor, and is arranged together with the auxiliary capacitor between the third node and the first reference ground;
a control terminal of the first switch is coupled to the first control potential; and
a control terminal of the second switch is coupled to the second control potential.
3 . The resonant converter as claimed in claim 2 , wherein
the first auxiliary switch set further includes a third switch, and the first switch, the auxiliary inductor, and the third switch are connected in series, and arranged together between the first node and the second node;
the second auxiliary switch set further includes a fourth switch, and the second switch, the auxiliary capacitor, and the fourth switch are connected in series, and arranged together between the third node and the first reference ground; and
the control terminals of the third switch and the fourth switch are coupled to an output potential of the output capacitor.
4 . The resonant converter as claimed in claim 1 , wherein
the first rectifying component and the second rectifying component are diodes;
the first terminals of the first rectifying component and the second rectifying component are anodes; and
the second terminals of the first rectifying component and the second rectifying component are cathodes.
5 . The resonant converter as claimed in claim 4 , wherein
the power switch circuit has a first power switch and a second power switch;
the first power switch and the second power switch are connected in series, and are arranged between the DC potential and the reference ground.
6 . The resonant converter as claimed in claim 5 , wherein
the first power switch and the second power switch perform complementary turn-on and turn-off operations according to a first switching potential and a second switching potential.
7 . The resonant converter as claimed in claim 6 , wherein
the controller outputs the first switching potential and the second switching potential; and
the first switching potential and the second switching potential are complementary pulse width modulation potential.