A DC-DC converter includes an inductor, a synchronous rectifier (SR) connected to the inductor, and an active switch connected to the inductor and the SR. An active resonant tank (ART) cell is connected to the SR or a transformer in parallel such that a resonant capacitor of the ART cell is charged through the active switch and discharged through the synchronous rectifier so that during a switch transition period energy is pumped out of the resonant capacitor by activating the ART cell to eliminate reverse recovery switching loss and achieve Zero Voltage Switching (ZVS).

A DC-DC power converter (100) that provides increased power density, reduced size, and reduced costs of manufacture. The DC-DC power converter (100) includes first and second input terminals (101, 102), a plurality of output terminals (116, 117), and at least one electrical element (108/109) connected to at least one of the first and second input terminals (101, 102). In the event a first voltage is applied across the first and second input terminals (101, 102), the electrical element (108/109) provides a second voltage having a value between the first voltage value and a reference voltage value. The DC-DC power converter (100) further includes a transformer (110) having a primary winding (111) and a secondary winding (112), and a switch assembly (103 107) operatively connected to the first input terminal (101), the second input terminal (102), the electrical element (108/109), and the transformer primary winding (111). In the event the first voltage is applied across the first and second input terminals (101, 102), the switch assembly (103 107) switchably applies the first, second, and reference voltages across the transformer primary winding (111) to generate at least one third voltage across the transformer secondary winding (112). The DC-DC power converter (100) further includes a rectifier (113) connected between the transformer secondary winding (112) and the output terminals (116, 117).

A converter topology that eliminates reverse recovery losses in its output rectifying semiconductor devices employs an AC injection voltage source in series with a power transformer primary winding. Input semiconductor switches in the converter's primary circuit are controlled to provide in the power transformer secondary a voltage across the winding or windings in a first direction forward biasing one of the output rectifying devices followed by a lower level reverse biasing voltage produced by the injection voltage. This lower level voltage across the secondary turns off the previously conducting rectifier device and drives carriers out of its semiconductor junction or junctions to eliminate reverse recovery losses occurring when the secondary applies a higher level reverse bias across the non-conducting rectifier device. The injection voltage source can be a transformer in addition to the power transformer having a primary winding in series with the primary winding of the power transformer and a secondary winding connected to ground through a capacitor. In addition to preventing reverse recovery losses in the rectifying devices in the secondary, the injection voltage transformer also injects an AC triangular waveform current into the current in the converter primary input circuit to the junction of the semiconductor switches where they are connected in a bridge circuit supplying the power transformer primary. By this, the injection voltage source assures zero voltage switching of the semiconductor switches even at light loads.

A single stage switch mode power converter receives a supply line voltage and a supply line current from a power supply line, and provides one or more regulated output voltages for a load, such as an amplifier. The power converter is operable to regulate the output voltage(s) using a controller that includes a voltage controlled current loop. The controller can enable substantially constant supply line current to be drawn from the power supply line by selectively allowing conduction of the supply line current through the power converter. A power factor of the supply line voltage and the supply line current may be optimized by the controller at medium to high power levels thereby maximizing the power provided to the switch mode power converter from the power supply line. Due to the adaptive nature of the controller, the power converter can operate over a wide range of supply line voltage.

A power converter may employ a planar transformer to minimize winding conduction loss, and the switching devices of the power converter may be aligned in lines parallel to an edge of the planar transformer to minimize the termination leakage inductance. The windings of the planar transformer may be thermally conductively coupled to one or more heat sinks carried by a circuit board which are with respective ones of the switching devices, to provide a cooling path for the planar transformer.