Resonant converters have a highly nonlinear and time-varying nature. Any change in operating conditions leads to significant changes in system dynamical model so that desired performance and even stability are lost. This situation is mainly due to variation in load and line voltage. Taking into consideration the uprising need for high-quality resonant power converters comes the need for modern and systemic approaches to the control of these systems. In this paper to access both satisfactory stability and satisfactory performance, such as reduced sensitivity to line voltage and load variations, satisfactory disturbance rejection, reduced output impedance, and attenuated transfer from input to output, we use the /spl mu/-synthesis technique for a zero-current switching (ZCS) converter.