An electronic converter receiving low frequency input power, converting this power to DC power at a voltage greater than the input voltage peak, and providing output power from a commutator stage. Lossless switching of the power semiconductor devices in the input stage is achieved by turning each device on at an instant when voltage across the device's current terminals is zero. Current through a main inductor of the input circuit is triangular and substantially unidirectional for at least a few high frequency cycles. To ensure lossless switching, current through the main inductor of the input circuit may be reversed briefly before switching. For use as an electronic arc lamp ballast, the commutator stage also uses lossless switching, and substantially unidirectional triangular current through an output inductor is reversed periodically.