Energy transfer circuit and method

A method for transferring energy to and from a load using an energy transfer circuit comprising a first capacitor, a second capacitor, an inductor, a first switch between the inductor and the first capacitor, a second switch between the inductor and the second capacitor, and a control unit, the method comprising:

• connecting the load in parallel with the first capacitor of the energy transfer circuit;
• connecting a primary energy source having a first voltage in parallel with the first capacitor of the energy transfer circuit;
• connecting a secondary energy source having a second voltage in parallel with the second capacitor of the energy transfer circuit;
• closing the first switch to put the primary energy source in parallel with the inductor and to transfer energy between the primary energy source and the inductor;
• closing the second switch to put the secondary energy source in parallel with the inductor and to transfer energy between the secondary energy source and the inductor;
• communicating status information from the primary energy source to the control unit;
• communicating status information from the secondary energy source to the control unit;
• communicating energy requests from the load to the control unit;
• controlling the opening and closing of the first switch and the second switch using the control unit;
• responding to charging currents from the load;
• responding to power demands from the load;
• responding to energy requests for the primary energy source and the secondary energy source;
• and
• keeping the first switch and the second switch open unless responding to the charging currents, power demands or energy requests from the load, the primary energy source or the secondary energy source;
• wherein responding to power demands from the load comprises:
• determining whether the power demand is a multiple source power demand or a single source power demand;
• executing a highpower routine when the power demand is the multiple source power demand;
• and
• executing a single unit power routine when the power demand is the single source power demand;
• and
• wherein executing a highpower routine comprises:
• determining whether the primary energy source is in a primary highload operating range;
• determining whether the secondary energy source is in a secondary highload operating range;
• transferring power from both the primary and secondary energy sources to the load when the primary energy source is in the primary highload operating range and the secondary energy source is in the secondary highload operating range;
• monitoring the state of charge of the primary and secondary energy sources;
• discontinuing the highpower routine when the primary energy source goes outside the primary highload operating range;
• discontinuing the highpower routine when the secondary energy source goes outside the secondary highload operating range;
• discontinuing the highpower routine when the power demand ceases;
• and
• discontinuing the highpower routine after a limited time.

A method for transferring energy to and from a load using an energy transfer circuit comprising a first capacitor, a second capacitor, an inductor, a first switch between the inductor and the first capacitor, a second switch between the inductor and the second capacitor, and a control unit, the method comprising:

• connecting the load in parallel with the first capacitor of the energy transfer circuit;
• connecting a primary energy source having a first voltage in parallel with the first capacitor of the energy transfer circuit;
• connecting a secondary energy source having a second voltage in parallel with the second capacitor of the energy transfer circuit;
• closing the first switch to put the primary energy source in parallel with the inductor and to transfer energy between the primary energy source and the inductor;
• closing the second switch to put the secondary energy source in parallel with the inductor and to transfer energy between the secondary energy source and the inductor;
• communicating status information from the primary energy source to the control unit;
• communicating status information from the secondary energy source to the control unit;
• communicating energy requests from the load to the control unit;
• controlling the opening and closing of the first switch and the second switch using the control unit;
• responding to charging currents from the load;
• responding to power demands from the load;
• responding to energy requests for the primary energy source and the secondary energy source;
• and
• keeping the first switch and the second switch open unless responding to the charging currents, power demands or energy requests from the load, the primary energy source or the secondary energy source;
• wherein responding to power demands from the load comprises:
• determining whether the power demand is a multiple source power demand or a single source power demand;
• executing a highpower routine when the power demand is the multiple source power demand;
• and
• executing a single unit power routine when the power demand is the single source power demand;
• and
• wherein executing a single unit power routine comprises:
• determining an operating condition of the primary energy source;
• determining an operating condition of the secondary energy source;
• transferring power from the primary energy source to the load when the primary energy source is in as good or better operating condition than the secondary energy source;
• transferring power from the secondary energy source to the load when the secondary energy source is in better operating condition than the primary energy source;
• discontinuing the single unit power routine when the power demand ceases;
• and
• discontinuing the single unit power routine after a limited time.