I- Introduction

II- Finite-State Model Predictive Control

III- Proposed Finite-State Model Predictive Control With Integral Action

IV- Model Predictive Control in SP-ZSI

V- Experimental Results

VI- Conclusion

References

Abstract

Finite-State Model Predictive Control (FSCMPC) can be applied to a power converter if there is an accurate existing model of the converter. The best results will be achieved if and only if the parameters and variables that make up the system are properly estimated. If this is not the case, the predictions made using these strategies may be erroneous and cause problems, such as steadystate error with respect to the assigned desired references. This work presents a predictive control strategy with integral action that compensates for the differences between the estimated model and the inverter with the objective of achieving zero steady-state error without requiring external loops or state observers. The proposed strategy is tested on a single-phase Z-source inverter (SPZSI) so as to evaluate the error in both the ac and dc controlled variables with respect to their references to their cosigns. The experimental results confirm that the proposed strategy achieves zero error in steady state while maintaining the fast dynamic response of the classic predictive control.

Introduction

Model Predictive Control (MPC), despite having been under development for nearly forty years, is still considered an emerging strategy in many industrial applications [1]-[3]. In applications that use power converters, Finite-State Model Predictive Control (FCS-MPC) has received attention from researchers and developers for more than a decade [4]-[7]. This interest is due to the fact that defining the mathematical models to predict the behavior of the variables in a converter is not usually very complicated; furthermore, the existence of inexpensive, powerful digital signal processors (DSP) for the implementation of these strategies is an advantage that was not available 20 or 30 years ago [8]-[10]. Nowadays, in the specific field of static power converters, three-phase and single-phase inverters are fundamental in power integration applications for incorporating renewable energy to the distributed grid systems, micro-grids and/or isolated systems [11]-[17]. Diverse types of inverters have been controlled using FS-MPC’s. This strategy has been proposed in voltage source inverters (VSI), current source inverters (CSI) and also in Z-source inverter and quasi Z-source inverter (ZSI/qZSI) impedance networks [18]. Z-source inverters (ZSI/qZSI) are among the least-known inverters because they were first proposed less than 20 years ago [19]-[23]. These inverters have the advantage that they can behave as boosters or dampers on the ac-side, unlike VSIs, which can only act as dampers, or CSIs, which work as boosters [26][27]. This characteristic of Z-source inverters is considered a great advantage because it does not require the use of dc/dc converters to extend its operating ranges, which is a common practice with VSI’s and CSI’s.