Abstract: A capacitor charger system has a resonant power converter to connect to a capacitor via a rectifier. The resonant power converter has a switch-based bridge network, an internal transformer, a resonant circuit, and an amplitude stabilization circuit. The switch-based bridge network comprises at least one pair of switches. The resonant circuit includes a series-resonant branch with capacitive and inductive components, and the resonant circuit is connected in the circuit path to a midpoint between a pair of switches of the switch-based bridge network. The amplitude stabilization circuit provides stabilization of the resonant amplitude of the resonant circuit, and the amplitude stabilization circuit includes one-way conducting circuitry connected between an unrestricted node defined by a junction and a connection point of the resonant power converter having a predefined voltage level at operation. The resonant power converter connects to the output rectifier via the secondary winding of the internal transformer.