Synchronous switching power supply
A method for powering one or more loads from a varying input voltage comprises controlling a primary switch to selectively apply the input voltage to energize an inductor, controlling a load switch to selectively connect the inductor to the load, monitoring one or more load parameters to determine load conditions, and, when the load conditions meet a load requirement, disconnecting the load from the inductor and directing any remaining current in the inductor to a energy storage element.
1. A power supply comprising:
a first winding selectably connectable to receive a varying input voltage through a primary switch;
a second winding inductively coupled to the first winding;
a load circuit comprising one or more loads selectably connectable to the second winding through one or more load switches;
a storage circuit comprising an energy storage element connected in a first polarity to the second winding through a reverse polarity protector;
a discharge circuit comprising a reverse switch for selectably connecting the energy storage element in a second polarity opposite to the first polarity to a third winding inductively coupled to the first and second windings; and,
a controller configured to monitor load conditions of the one or more loads and generate control signals for controlling the primary switch, the one or more load switches, and the reverse switch.
2. A power supply according to claim 1 wherein the reverse polarity protector comprises a diode.
3. A power supply according to claim 1 wherein the reverse polarity protector comprises a forward switch, and wherein the controller is configured to generate a control signal for controlling the forward switch.
4. A power supply according to claim 1 wherein the varying input voltage comprises a rectified AC voltage having a first frequency, and wherein the controller controls the primary switch at a second frequency substantially higher than the first frequency.
5. A power supply according to claim 4 wherein the second frequency exceeds 1 MHz.