FPGA Implementation of Passivity-Based Control and Output Load Algebraic Estimation for Transformerless Multilevel Active Rectifier

This paper presents the design and embedded implementation of a robust controller for the transformerless multilevel active monophase rectifier. In order to reduce the effects caused by the uncertainty originated by the output load, an algebraic estimator is devised. Then, a linear controller based on the exact static error dynamics passive output feedback (ESEDPOF) is proposed, where the uncertainty estimation is taken into account. Since the controller estimator is based on the continuous-time plant model, its real-time implementation on a digital platform requires a discretization of the controller under sufficiently fast sampling, such that the properties of the closed-loop nonlinear sampled-data system are preserved. For this reason, the medium-scale field-programmable gate array Spartan-6 XC6SLX16 is used for implementing the ESEDPOF controller, the online algebraic estimator, the enhanced phase-locked loop, and the multilevel pulsewidth modulator. The parallel processing provided by these devices and the capability in the design of custom modules allow optimizing the hardware description and obtaining an update time for the control law of 9.683 μs. Experimental validation shows an excellent dynamical performance and a near-unity power factor.