Patent ID: 8115460

Claim:
A power converter comprising: a control circuitry arranged to control the power converter at a fixed frequency; a first electric coil, a first end of said first electric coil connected to an input of the power converter and a second end of said first electric coil connected to an output of the power converter, at least one of said connection to the input and said connection to the output being a non-switchable connection; a first electronically controlled switch associated with said first electric coil and responsive to said control circuitry, said first electronically controlled switch arranged, responsive to a closed state of said first electronically controlled switch, to produce a current flowing in a first direction in said first electric coil so as to charge said first electric coil in the first direction, in cooperation with an input voltage; and a second electronically controlled switch associated with said first electric coil and responsive to said control circuitry, said second electronically controlled switch at all times arranged, responsive to a closed state of said second electronically controlled switch, to discharge said first electric coil when said first electric coil exhibits a current flowing in said first direction and to contiguously charge said first electric coil in a second direction, opposing said first direction, so as to produce a current flowing in said second direction in said first electric coil; and a third electronically controlled switch associated with said first electric coil, and responsive to said control circuitry, said third electronically controlled switch arranged, responsive to a closed state of said third electronically controlled switch, to present a substantially short circuit across said first electric coil, and said third electronically controlled switch not arranged to either charge or discharge said first electric coil, wherein said control circuitry is arranged to: alternately open and close said first electronically controlled switch such that a current flowing in said first direction is produced in said first electric coil not substantially greater than a value determined responsive to a load; alternately open and close said second electronically controlled switch such that a current flowing in said second direction is produced in said first electric coil and is sufficient to set the voltage across said first electronically controlled switch to zero when said second electronically controlled switch is open; and alternately open and close said third electronically controlled switch so as to maintain the fixed frequency of the power converter regardless of the length of time wherein each of said first and second electronically controlled switches are closed, wherein each of said first, second and third electronically controlled switches are closed only when substantially zero voltage is presented there across.