Digital controllers are used for modern power converter control and industrial automation. The functionality of the finite state machine (FSM) provides an ideal platform for building a high-frequency field programmable gate array (FPGA) controller for power electronics’ applications. This paper develops the design of a current control-loop and the selection of switching logic for three-phase switching converters and AC electrical machines. The main design specifications are robustness to load and electrical parameters, fast dynamical response, reduced switching frequency and simple hardware implementation. A discrete-event type controller is proposed to meet previous specifications, designed as finite-state automaton and implemented with a FPGA device. After a general introduction, system analysis is explained, control targets are specified together with the proposed FSM-based rules, the Event-Condition-Actions and the strategy are presented and discussed. Further more, the actual controller architecture is based on the FPGA Spartan 3E. The experimental results are presented using a brushless AC motor as the converter load. However, this does not limit the wider applicability of the proposed controller as it is suitable for different types of AC loads (rectifier, inverter).
COBISS.SI-ID: 16448534
This paper presents the derivation of a linear model with changeable parameters of constant frequency peak current mode controlled DC/DC boost converter supplied by a PEM fuel cell stack. The derived model has the same structure irrespective of the conduction mode and therefore, it is suitable for design of simple and advanced controllers of the output voltage. Experimental results on the system with 450 W boost converter supplied by PEM fuel cell emulator show that the derived model accurately describes the system in a given operating point, determined by the load resistance or output current.
COBISS.SI-ID: 15492886
This paper proposes a FPGA-based Sliding Mode Controller for scaled bilateral teleoperation. The control algorithm is derived by using the sliding mode control based design approach. The applied design procedure replaces a discontinuous control with a continuous one. Thus, it guarantees chattering-free performance whilst retaining practical robustness regarding disturbances, and provides easy model-free implementation. A high control rateis strongly required in order to achieve high-performance scaled bilateral teleoperation. Hence, the control algorithm is implemented by the FPGA. In order to design a sufficient logic circuit for the FPGA, general optimization approaches are presented that aim to minimize hardware resources, and to optimize the control rate. The design applies high-level programming language (LabVIEW) for rapid prototyping. The presented algorithms were validated by the 2- DoF laboratory bilateral teleoperation system.
COBISS.SI-ID: 16563990
This article introduces a new method for nano-Henry inductance measurements atthe frequency of 4.999 MHz with a single quartz crystal oscillating in the switching oscillating circuit. The real novelty of this method, however, lies in a considerable reduction of the temperature influence of AT-cut crystal frequency change in the temperature range between 0 °C and 50 °C through a switching method which compensates for the crystalćs natural temperature characteristics. This allows for the compensation of any influences on the crystal such as the compensation of the non-linear temperature characteristicsand the ageing of both the crystal and other oscillating circuit elements, as well as the reduction of the output frequency measurementerrors with the help of an additional reference frequency. The experimental results show that the switching method greatly improves the measurement of small inductance changes in the range between H and nH, allowing as a result high-precision measurements (~0.35 fH) in this range.
COBISS.SI-ID: 15832598
In recent years, Proton-Exchange Membrane Fuel Cells (PEMFCs) have been the focus of very intensive researches. Manufacturers of these alternative power sources propose a rejuvenation sequence after the FC has been operating at high power for a certain period of time. These rejuvenation methods could be not appropriate for the reactivation of the FC when it has been out of operation for a long period of time or after it has been repaired. Since the developed reactivation system monitors temperature, current, and the cell voltages of the stack, it could be also useful for the diagnostic and repairing processes. The limited number of published contributions suggests that systems developing reactivation techniques are an open research field. In this paper, an automated system for reactivating PEMFCs and results of experimental testing are presented.
COBISS.SI-ID: 16130070