Automated modeling and implementation of power converters on a real-time FPGA-based emulator

• Main Author: De Cuyper, Kevin
• Other Authors: Robert, Frédéric
• Format: Doctoral Thesis
• Language: en
• Published: Universite Libre de Bruxelles 2015
• Subjects: Théorie des circuits; Electronique et électrotechnique; Unités digitales de traitement; Automatique; Capteurs et périphériques; Electronique générale; Informatique appliquée logiciel; power electronics; FPGA; circuit analysis; real-time emulation
• Online Access: https://dipot.ulb.ac.be/dspace/bitstream/2013/221698/4/Thesis.pdf; https://dipot.ulb.ac.be/dspace/bitstream/2013/221698/3/Thesis_TDM.pdf; https://dipot.ulb.ac.be/dspace/bitstream/2013/221698/5/contratKD.pdf; http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/221698

Designing a new power electronic conversion system is a multi-step process that requires the R\&D team(s) to go through an extended prototyping phase whose goal is to validate the design in its nominal state, as well as to test its behavior when it is subjected to abnormal conditions. To properly and safely validate all devices that are external to the power stage itself, such as the controllers and the protection systems, one of the best-suited device is a real-time emulator of the converter circuit, a platform that obeys the same mathematical laws and produces the same signals as the original device withoutactually realizing the power conversion. Unfortunately, these models are often based on analog solvers which are difficult to build, must be redesigned for each modification and are subject to drift and aging. While multiple digital real-time emulators have appeared on the market in the last decades, they typically require powerful and expensive computing platforms to perform their calculations or are not generic enough to emulate the more complex power circuits. In this work, we present a new framework that allows the rapid prototyping of a wide range of power converters by translating a power converter schematic drawn on a computer to a real-time equivalent set of equations which is processed by an FPGA with an emulation time-step of less than one microsecond. Contrary to the previously published works, our tools enable the use of entry-level FPGAs even for the emulation circuits composed of twenty switches or more. This framework takes the form of a tool-chain that starts by extracting the necessary information and a standard description from the initial circuit. However, due to the intricate ways in which the switches and diodes can change their state, this raw information is too complex to be processed and emulated directly.Our first major contribution to the state of the art is a way to automatically analyze these changes in order to reduce the complexity of the problem as much as possible while keeping all the necessary information intact. In this thesis, we develop two tools that are able to find all possible changes in the state of the switches that may appear in the immediate future, thereby reducing the quantity of information required to emulate the circuit. Thanks to the global optimization provided by our tools, simulating a typical AC-to-DC converter composed of 12 switches could require 80\% less resources when compared to existing emulators.To enable the emulation or large power converters, we have created a partitioning method which divides the circuit in multiple sub-circuits which are analyzed and optimized separately. The performances of this partitioning are demonstrated by the emulation of a three-phase three-level converter with a relative error of a less that 5% on the signals.To handle our new framework, a dedicated digital platform has been developed. In order to provide the best results even on small FPGAs, particular attention is given to the low resources usage and the low latency of our design. Through multiple examples, we show that this inexpensive real-time emulation platform is able to accurately emulate many circuits in open- or closed-loop operation with a sampling rate higher than 1 MHz === Doctorat en Sciences de l'ingénieur et technologie === info:eu-repo/semantics/nonPublished