Charger circuit and transformer used therein
The present invention discloses a transformer used in a charger circuit, in which the input side of the transformer is connected to an AC input and PWM control circuit of the charger circuit, the output side of the transformer is connected to a constant current and/or constant voltage control circuit of the charger circuit. The AC input, PWM control circuit, the constant current and/or constant voltage control circuit are coupled through an optical coupling element, wherein the transformer includes a main output winding and an auxiliary output winding, and the auxiliary output winding is used to supply power for the optical coupling element and the constant current and/or constant voltage control circuit. The present invention further provides a high performance charger circuit adopting the transformer described above for improving electromagnetic compatibility, conversion efficiency and short circuit characteristic.
1. A transformer used in a charger circuit, in which the input side of the transformer is connected to an AC input and PWM control circuit of the charger circuit, and the output side of the transformer is connected to a constant current and/or constant voltage control circuit of the charger circuit. The AC input, PWM control circuit, constant current and/or constant voltage control circuit are coupled through an optical coupling element, wherein:
the transformer comprises a main output winding and an auxiliary output winding, and the auxiliary output winding is used to supply power for the optical coupling element and the constant current and/or constant voltage control circuit.
2. The transformer as claimed in claim 1 , wherein the main output winding and the auxiliary output winding are series connected or are independent windings.
3. The transformer as claimed in claim 2 , wherein the auxiliary output winding supplies power for the constant current and/or constant voltage control circuit through a flyback circuit.
4. The transformer as claimed in claim 3 , wherein the first end of the main output winding is connected to the positive electrode of a first diode, the positive electrode of the first diode is connected to the positive terminal of a first capacitor, and the negative terminal of the first capacitor is connected to the second terminal of the main output winding; and
the first terminal of the auxiliary output winding is connected to the first terminal of the main output winding and also connected to the positive electrode of the first diode, the second terminal of the auxiliary winding is connected to the optical coupling element, the constant current and/or constant voltage control circuit through the second diode, resistor and the second capacitor, which are series connected.
5. The transformer as claimed in claim 4 , wherein a connecting point located between the resistor and the second capacitor is drawn out for providing power to the optical coupling element and the constant current and/or constant voltage control circuit.
6. A charger circuit, comprising an AC input and PWM control circuit, a transformer, and a constant current constant voltage control circuit, wherein the constant current constant voltage control circuit and the AC input and PWM control circuit are coupled through an optical coupling element, the input side of the transformer is connected to the AC input and PWM control circuit of the charger circuit, and the output side of the transformer is connected to the constant current constant voltage control circuit of the charger circuit, characterized in that:
the transformer comprises a main output winding and an auxiliary output winding, and the auxiliary output winding is used to supply power for the optical coupling element and the constant current constant voltage control circuit.
7. The charger circuit as claimed in claim 6 , wherein the main output winding and the auxiliary output winding are series connected or are independent windings.
8. The charger circuit as claimed in claim 7 , wherein the auxiliary output winding supplies power for the constant current constant voltage control circuit through a flyback circuit.
9. The charger circuit as claimed in claim 8 , wherein the first end of the main output winding is connected to the positive electrode of a first diode, the positive electrode of the first diode is connected to the positive terminal of a first capacitor, and the negative terminal of the first capacitor is connected to the second terminal of the main output winding; and
the first terminal of the auxiliary output winding is connected to the first terminal of the main output winding and also connected to the positive electrode of the first diode, the second terminal of the auxiliary winding is connected to the optical coupling element and the constant current constant voltage control circuit through the second diode, resistor and the second capacitor, which are series connected.
10. The charger circuit as claimed in claim 9 , wherein a connecting point located between the resistor and the second capacitor is drawn out for providing power for the optical coupling element, the constant current, and/or constant voltage control circuit.