The discrete model of the power stage of the voltage source inverter for UPS

This article presents a new generalised discrete model of the power stage of single-and three-phase inverters including the calculations of the output filter parameters that provide an acceptable level of output voltage harmonics. The presented model can be used with the pole placement control methods such as the coefficient diagram method or the deadbeat one sampling ahead preview control. Discrete modelling of the power stage including properties of the PWM modulator makes an easy description of the chosen control law that can be directly implemented in the control software possible. The final simulation and the experimental verification of the poles placement methods in the voltage source inventer control confirm the usefulness of the presented model but some differences between the control theory and the inverter measurements are expected.