Extended range boost converter circuit

A power converter comprising:

• a power transformer having a primary winding and a secondary winding flux coupled to the primary winding;
• input means for receiving an input voltage;
• output means for providing an output voltage;
• a single winding inductor coupled between the input means and the primary winding;
• a switching arrangement comprising a plurality of switches which are switched on and off according to a duty cycle for controllably causing a flow of current from the primary winding;
• means for controlling the duty cycle of said switching arrangement;
• unidirectional conduction means coupled to the transformer secondary winding for rectifying flux coupled energy to provide an output voltage Vo to the output means;
• and
• means coupled to an output terminal of the inductor for providing a current path for discharging the inductor during a predetermined time interval associated with a portion of the duty cycle of the switching arrangement when said plurality of switches are off to enable the power converter to operate in a mode where the output voltage Vo is lower than the input voltage.

A buck-boost converter comprising:

• a power transformer having a primary winding and a secondary winding of a given turns ratio;
• input terminals for receiving an input voltage;
• output terminals for providing an output voltage;
• a single winding inductor coupled between the input terminals and the primary winding;
• a switching arrangement comprising a plurality of switches to be turned on and off according to a duty cycle for controllably causing a flow of current through the primary winding;
• a controller for controlling the duty cycle of said switching arrangement;
• unidirectional conduction means coupled to the transformer secondary winding for rectifying flux coupled energy to provide an output voltage Vo to the output means;
• means coupled to an output terminal of the inductor and operable in a first mode for providing a path for discharging the inductor during a predetermined time interval associated with a portion of the duty cycle of the switching arrangement when said plurality of switches are each off to enable the boost converter to operate in a first mode where the voltage Vo is lower than the input voltage, and operable in a second mode for providing a path for discharging energy associated with leakage inductance reflected to the output terminal of said single winding inductor when the boost converter is operated in a second mode wherein said plurality of switches are each on during a same portion of said duty cycle.

In a boost converter comprising a power transformer having a primary winding and a secondary winding flux-coupled to the primary winding, input terminals for receiving an input voltage;

• output terminals for providing an output voltage;
• a switching arrangement coupled to said transformer comprising a plurality of switches to be turned on and off according to a duty cycle for controllably causing a flow of current through the primary winding of said transformer such that the output voltage is greater than the input voltage;
• means for controlling the duty cycle of said switching arrangement;
• unidirectional conduction means coupled to the transformer secondary winding for rectifying flux coupled energy to provide the output voltage Vo to the output means, the improvement comprising:
• a single winding inductor coupled between the input means and the primary winding;
• and
• an operating circuit coupled to an output terminal of the inductor for providing a path for discharging energy associated with leakage inductance reflected to the output terminal of the inductor through the switch arrangement back to the input means, whereby the energy is recovered and recycled through the boost converter.