Passivity-Based Control Design Methodology for UPS Systems

Abstract

This paper presents a passivity-based control (PBC) design methodology for three-phase voltage source inverters (VSI) for uninterruptable power supply (UPS) systems where reduced harmonic distortions for the nonlinear load, reduced output voltage overshoot, and a restricted settling time are required. The output filter design and modification for efficient control and existing challenges with the assignment of scaling coefficients of the output voltage, load, and inductor currents are addressed and analyzed. Notably, special attention is given to the modulator saturation issue through implementing an accurate converter model. Applications of the two versions of PBC in three-phase voltage source inverters using stationary αβ and rotating dq frames for a constant frequency of the output voltage are presented. Furthermore, the influence of the PBC parameters on the power converter performance is investigated. A comparative simulation and the experimental results validate the effectiveness of the presented passivity-based control design methodology.

Different Features of Control Systems for Single-Phase Voltage Source Inverters

“…The restrictions of the K v and R i gains in the MISO-IPBC2 (Figures 5-7) complicate its further improvement. The requirement of the restriction of the product of the modulation index M and the filter inductor value L F (the higher the L F , the lower the M) is a problem that exists for all the controller types and was described, e.g., in [39,40].…”

“…The equilibrium of a closed-loop system is asymptotically stable [38] and is achieved if H(e) has a minimum in x = x ref in Equation (40),…”

“…However, in the simulations and in the experimental model, overly high values of R i and K v led to oscillations in the control voltage and output voltage (Figure 5). An overly high value of modulation index M [39,40] for the nonlinear rectifier RC load led to the saturation of the PWM modulator (Figure 6). Both of these cases produced the same result.…”

“…Both of these cases produced the same result. The reason can be the disability of fast current changing in the filter inductor [40]. Therefore, the best adjustment of the PBC controller gains R i and K v is to determine the lowest THD (for the nonlinear rectifier RC load).…”

A State-Space Approach to the Modelling and Control of the Neutral Leg of a Four Legs, Three-Phase Inverter

“…In order to connect AC sources to the grid, two stages are generally used: a first inverter is used as a rectifier and the second inverter connects the so-obtained DC bus to the AC grid. In addition, inverters are also used for active power filter [6,7] and uninterruptible power supply applications [8,9]. Low voltage grids are usually 4-wire (i.e., three-phase with neutral connection), therefore an appropriate management of the neutral line should be conceived for the inverter.…”