Half-bridge flyback power converter
View Patent ↗A half-bridge flyback power converter is provided. The half-bridge flyback power converter comprises a high-side switch and a low-side switch periodically conducting an input voltage to a primary winding of a transformer. When the high-side switch and the low-side switch are switched off, energy stored in the transformer is transmitted to a secondary circuit and serves to charge a bulk capacitor. A forward diode facilitates to combine the input voltage with a voltage across the bulk capacitor for powering the secondary circuit. Therefore, the power consumption of the leakage inductance is reduced and circuit topology is simplified.
1. A half-bridge flyback power converter, comprising:
a transformer, having a primary winding and a secondary winding, wherein said secondary winding is coupled to a secondary circuit; wherein a first terminal of said primary winding and a first terminal of said secondary winding have same polarity;
a high-side switch;
a low-side switch, wherein said high-side switch is coupled between an input voltage and a second terminal of said primary winding; wherein said low-side switch is coupled between said first terminal of said primary winding and a ground reference level;
a first flyback diode, wherein an anode of said first flyback diode is coupled to said ground reference level; wherein a cathode of said first flyback diode is coupled to said second terminal of said primary winding;
a second flyback diode, having an anode coupled to said first terminal of said primary winding;
a bulk capacitor, wherein a positive terminal of said bulk capacitor is coupled to a cathode of said second flyback diode; wherein a negative terminal of said bulk capacitor is coupled to said ground reference level; and
a forward diode, having a cathode coupled to said input voltage and an anode coupled to said positive terminal of said bulk capacitor.
2. The half-bridge flyback power converter as recited in claim 1 , wherein said high-side switch and said low-side switch periodically conduct said input voltage to said primary winding of said transformer in response to at least a control signal.
3. The half-bridge flyback power converter as recited in claim 1 , wherein when said high-side switch and said low-side switch are switched off, energy stored in said transformer is transmitted to said secondary circuit and serves to charge said bulk capacitor through said first flyback diode and said second flyback diode.
4. The half-bridge flyback power converter as recited in claim 1 , wherein said forward diode facilitates to combine said input voltage with a voltage of said bulk capacitor; wherein when said input voltage is lower than a voltage across said bulk capacitor, energy stored in said bulk capacitor serves to power said secondary circuit.
5. The half-bridge flyback power converter as recited in claim 1 , wherein energy of the leakage inductor of said transformer is stored in said bulk capacitor when said high-side switch and said low-side switch are switched off.
6. The half-bridge flyback power converter as recited in claim 1 , wherein said bulk capacitor is only charged by magnetized energy and leakage inductor energy of said transformer.