A simple design approach for discrete time resonant controllers for UPS applications

This paper proposes a simple design approach for discrete time resonant controllers to control the output voltage of a single-phase PWM inverter used on UPS applications. The design procedure is based on the analysis of relative stability margins and its relationship with the transient response specifications established by the IEC 62040-3 standard, and the steady state response specifications given by IEC 61000-2-2. The control strategy is based on an inner current loop using a proportional controller, and an external voltage control loop using resonant controllers. The simulation results for a 2kVA single-phase PWM inverter validate the design approach.