Authors:
Eyke Liegmann;Petros Karamanakos;Ralph Kennel;
Pages: 1 - 12 Abstract: This paper deals with the real-time implementation of a long-horizon finite control set model predictive control (FCS-MPC) algorithm on an embedded system. The targeted application is a medium-voltage drive system which means that operation at a very low switching frequency is needed so that the switching power losses are kept relatively low. However, a small sampling interval is required to achieve a fine granularity of switching, and thus ensure superior system performance. This renders the real-time implementation of the controller challenging. To facilitate this, a high level synthesis (HLS) tool, which synthesizes C++ code into VHDL, is employed to enable a higher level of abstraction and faster prototype development of the real-time solver of the long-horizon FCS-MPC problem, namely the sphere decoder. Experimental results based on a small-scale prototype, consisting of a three-level neutral point clamped (NPC) inverter and an induction machine, confirm that the algorithm can be executed in real time within the targeted control period of 25 $mu$s. PubDate:
2022
Issue No:Vol. 3 (2022)
Authors:
Mi Tang;Marco di Benedetto;Stefano Bifaretti;Alessandro Lidozzi;Pericle Zanchetta;
Pages: 13 - 29 Abstract: Power electronic systems present a non-linear behavior mainly due to their switching nature. This is often combined with their interaction with non-linear systems, such as other switching converters, diode rectifiers, motor drives, etc. and with possible non linearities of the power grid in the case of grid connected systems. The major effect of these non-linear interactions is the generation of harmonic distortion on voltages and currents (both in DC and AC), which needs to be compensated to achieve high power quality systems. The use of passive filters is often the simplest and most immediate solution; however, this decreases converter efficiency and increases its weight and volume. Thus, the use of a control strategy capable of tracking periodic signals, rejecting periodic disturbance and largely improving steady state behavior and harmonic distortion with a limited bandwidth is a very desirable feature. Repetitive Control (RC) represents an extremely practical and efficient solution for the aforementioned issues, and it is widely employed in many different applications. This paper focuses on state of the art of RC used in power electronics and drives. RC basic concepts, different control structures, design methods, fixed and variable frequency operating conditions, etc. are investigated. Furthermore, many example applications and existing control approaches developed in recent years for power electronics and drive systems based on RC, have also been discussed in detail. PubDate:
2022
Issue No:Vol. 3 (2022)
Authors:
Ali S. Haider;Ted K. A. Brekken;Ryan G. Coe;Giorgio Bacelli;Alan McCall;
Pages: 30 - 40 Abstract: The growing wave energy sector requires an efficient and flexible testing process for the development phase of wave energy systems. Real-time hybrid testing is a promising technique for the accelerated testing of wave energy conversion systems. This article presents an experimental study on developing a hybrid testing platform for wave energy systems at the Wallace Energy System and Renewables Facility (WESRF) at Oregon State University. The wave energy conversion system is broken down into numeric (i.e., virtual) and physical (i.e., hardware) components. The numeric component involves software components such as the control algorithm for Wave Energy Converter (WEC) and controller for the power electronic converters and numerical models for the WEC device hydrodynamics. The hardware involves an ocean wave emulator testbed, Power Take-Off (PTO) mechanism, power electronics, and instrumentation. The numeric components are implemented in a real-time target machine and are interfaced with the experimental system. A case study implementation of Nonlinear Model Predictive Control (NMPC) is presented for a single degree of freedom heaving nonlinear WEC model with a Permanent Magnet Synchronous Generator (PMSG) as a PTO system. A Field-Oriented Control (FOC) algorithm controls the PMSG-PTO generation using a three-phase Integrated Intelligent Power (IIP) module converter. A demonstration of the proposed hybrid testing setup is provided. PubDate:
2022
Issue No:Vol. 3 (2022)
Authors:
Tadashi Mizobuchi;Keiichiro Kondo;Yosuke Dairaku;Takeshi Shinomiya;Katsumi Ishikawa;
Pages: 41 - 55 Abstract: The hybrid-voltage-source three-level inverter is a traction circuit system aimed at realizing energy savings with lithium-ion batteries for direct-current-electrified railway vehicles. However, this system has the limitation of being unable to freely control the power flow of the batteries owing to the pulse width modulation. However, because this system has batteries, energy management is required for the batteries. Therefore, it is necessary to propose an energy-management method that achieves the required energy-saving effect while considering the constraints of the battery power control. In this paper, a management method is proposed to control the power flow of the batteries by determining the pulse mode of the inverter and the modulation wave offset based on the state of the charge and inverter frequency. In a 0.75-kW class mini-model verification, the effectiveness of the proposed energy-management method is then confirmed based on the state of the charge, inverter frequency, offset, and battery power. Subsequently, we evaluate the energy-saving effect of this hybrid system using a numerical simulation while considering an actual railway vehicle. In addition, the optimal capacity of the batteries is investigated. As a result, the best energy-saving effect is obtained when two of the assumed batteries are connected in series and three in parallel, and the power consumption is reduced by approximately 21%. PubDate:
2022
Issue No:Vol. 3 (2022)
Authors:
Hans Bärnklau;Jens Proske;
Pages: 56 - 65 Abstract: During synchronization phase of a doubly fed induction machine prototype abnormal high voltages were recorded at stator terminals. By evaluating the measured curves, and the frequency response of a similar machine, these overvoltages could be traced back to differential mode resonance effects within the machine itself. The effect of differential mode resonance is not restricted to doubly fed induction machines but also occurs in other machine types such as squirrel cage induction machines. If not considered in the insulation design, such abnormal voltages will lead to a premature ageing of the insulation. Depending on the operating conditions, premature failures may occur. The measured data presented in the article give an illustrative example what could happen if windings of electric machines are excited near series resonance frequency. As the occurence of this effect becomes more probable the higher the switching frequency of the converter, it is thoroughly important to be aware of it. PubDate:
2022
Issue No:Vol. 3 (2022)
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