A zero-voltage transition pulse width modulation, PWM, resonant converter comprising: a direct current, DC, bus including a first rail and a second rail; a first switching device coupled with the first rail and a converter output node; a second switching device coupled with the second rail and the converter output node; a resonant tank circuit comprising a first resonant capacitor, a second resonant capacitor, and a resonant inductor coupled with the converter output node; an auxiliary circuit including a plurality of auxiliary switching devices (121, 123, 125, 127) coupled in series between the first rail and the second rail and a flying capacitor coupled in parallel across two of the auxiliary switching devices (123, 125), the resonant inductor being coupled to a node intermediate the said two of the auxiliary switching devices (123, 125); and a controller structured to control the first switching device, the second switching device, and the plurality of auxiliary switching devices (121, 123, 125, 127) to provide resonant operation of the tank circuit effective to provide a zero voltage condition across the first switching device when turning the first switching device on or off and to provide a zero voltage condition across the second switching device when turning the second switching device on or off, wherein the plurality of auxiliary switching devices (121, 123, 125, 127) comprise first, second, third and fourth auxiliary switching devices coupled in series between the first rail and the second rail, the flying capacitor is coupled in parallel across the second and third auxiliary switching devices (123, 125), and the resonant inductor is coupled to the node intermediate the second and third auxiliary switching devices (123, 125), characterized in that the controller is structured to execute a commutation scheme in which the first auxiliary switching device is turned on at a first time with the first switching device off and the second switching device on effective to increase the resonant inductor current and the second switching device is turned off under the zero voltage condition at a second time greater than the first time effective to provide resonant operation of the tank circuit. a direct current, DC, bus including a first rail and a second rail; a first switching device coupled with the first rail and a converter output node; a second switching device coupled with the second rail and the converter output node; a resonant tank circuit comprising a first resonant capacitor, a second resonant capacitor, and a resonant inductor coupled with the converter output node; an auxiliary circuit including a plurality of auxiliary switching devices (121, 123, 125, 127) coupled in series between the first rail and the second rail and a flying capacitor coupled in parallel across two of the auxiliary switching devices (123, 125), the resonant inductor being coupled to a node intermediate the said two of the auxiliary switching devices (123, 125); and a controller structured to control the first switching device, the second switching device, and the plurality of auxiliary switching devices (121, 123, 125, 127) to provide resonant operation of the tank circuit effective to provide a zero voltage condition across the first switching device when turning the first switching device on or off and to provide a zero voltage condition across the second switching device when turning the second switching device on or off, wherein the plurality of auxiliary switching devices (121, 123, 125, 127) comprise first, second, third and fourth auxiliary switching devices coupled in series between the first rail and the second rail, the flying capacitor is coupled in parallel across the second and third auxiliary switching devices (123, 125), and the resonant inductor is coupled to the node intermediate the second and third auxiliary switching devices (123, 125), characterized in that the controller is structured to execute a commutation scheme in which the first auxiliary switching device is turned on at a first time with the first switching device off and the second switching device on effective to increase the resonant inductor current and the second switching device is turned off under the zero voltage condition at a second time greater than the first time effective to provide resonant operation of the tank circuit.