Low loss boost converter
View Patent ↗The present invention relates to a low loss boost circuit used in power conversion equipment of power supplies or other power systems. It comprises controlling a duty cycle of a power switch; realizing voltage boosting and regulating of the output voltage through the energy storage in a boost inductor; reducing the reverse recovery current using an auxiliary inductor, wherein a secondary winding of the inductor supplies additional energy thereto and provides a path for transferring the energy from the auxiliary inductor to the energy storage capacitor. The present invention has high efficiency and is suitable for power converter with PFC, such as, telecommunication power supply and uninterrupted power supply.
1. A method for controlling a boost circuit comprising the steps of:
controlling a duty cycle of a power switch by controlling on and off of the power switch;
realizing voltage boosting and regulating of the output voltage across an output capacitor using energy storage of an inductor; and
reducing the reverse recovery current of a freewheeling diode through an auxiliary inductor connected in series with the power switch, wherein a secondary winding of the inductor is connected to an energy storage capacitor to supply the energy thereto, and to provide a path for the auxiliary inductor, thereby transferring the energy to the storage capacitor.
2. The method of claim 1 further comprising the steps of:
the storage capacitor obtaining additional energy through the secondary winding of the inductor while storing the reverse recovery energy after the power switch is turned on; and
the energy storage capacitor transferring the stored reverse recovery energy and the additional energy to the output capacitor during the freewheeling stage after the power switch is turned off.
3. An apparatus for a low loss boost circuit comprising a boosting circuit including a power switch, an inductor including a primary winding and a secondary winding, a freewheeling diode, and an output capacitor, the freewheeling diode being connected in series with an auxiliary inductor, wherein an energy storage circuit is provided and is connected across the cathode and the anode of the freewheeling diode and the ground, the energy storage circuit including the secondary winding of the inductor coupled to an energy storage capacitor.
4. The circuit of claim 3 wherein the energy storage circuit further includes first and second auxiliary diodes, the first auxiliary diode and the second auxiliary diode being connected between the secondary winding and the cathode of the freewheeling diode in series and wherein the energy storage capacitor is arranged between a junction which connects the first auxiliary diode and the second auxiliary diode and a junction which connects the freewheeling diode and the auxiliary inductor.
5. The circuit of claim 4 wherein the energy storage circuit further comprises a third auxiliary diode having an anode connected to a junction between the primary winding of the inductor and the power switch, and its cathode connected to the cathode of the freewheeling diode.