Patent ID: 7602157

Claim:
A system to transfer energy between an energy supply and a resistive or inductive load, the system comprising: at least one power stage, each power stage comprising: an input connectable to a source having a unipolar voltage; an output connectable to a load that comprises an inductance; an input switch operable to connect the input to the output during a first portion and a second portion of a time period, and to substantially isolate the input from the output during other portions of the time period; an energy capture circuit operable during a third portion of the time period to store inductive energy that is present in the load at the end of the second portion of the time period; a voltage limiting circuit operable to limit a voltage associated with the load inductance during a fourth portion of the time period, wherein the fourth portion of the time period extends from the end of the second portion of the time period until the third portion of the time period; and an energy recovery circuit operable during the first portion of the time period to supply stored energy from the energy capture circuit to the input, wherein the first portion of the time period precedes the second portion of the time period, and the second portion of the time period precedes the third portion of the time period.