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This paper describes the development of a novel three-phase phase-locked loop (PLL) used to compensate for mains variations by being incorporated as part of a feedforward loop in a three-phase telecommunications power converter. A telecommunications converter must comply with industry standards, in particular the psophometric noise standard CCIF-1951; this is achieved by controlling the output voltage...
The present research study is focused on the design, development and validation of a device based on multilevel converter for medium voltage distribution networks. It regulates the reactive power exchanged with the grid (up to 3 MVAR), allowing to achieve the following objectives: Network voltage regulation, reactive power compensation and power factor control. The device is composed by an IGBT based...
In the field of electrical solar power conversion efficiency is the most important topic. In most applications a special DC-to-DC converter is necessary to couple the solar cells, operating at low DC voltages, to the inverter's DC-link. These converters with rather low input respectively high output voltage ratings have, due to the high current ratings, a relatively low efficiency. Therefore, a special...
The main objective of the paper is to present new browser-based, interactive software tools for modeling of various power electronics circuits. The static and dynamic operation, including the continuous and discrete time linearization of widely applied DC-DC converter cells are discussed in the first part of the paper. The second part focuses on the basics of the pulse-width-modulation and its application...
This paper presents a study and experimentation of a hybrid energy storage system prototype, based on Compressed Air, where the charging and discharging is done within maximum efficiency conditions of the volumetric machine. As the maximum efficiency conditions impose the level of the converted power, an intermittent time-modulated operation mode is applied to the thermodynamic converter to obtain...
The paper discuss the design and performance of a laboratory rig which is used to evaluate different variable/adjustable speed generating system topologies. A programmable torque speed characteristics of a DC machine controlled by a thyristor converter is used as simulator of the different driving engines. The electrical supply is provided by an axial flux permanent magnet generator and AC/AC converter...
Small size hydro plants are commonly constituted of fixed speed drives. To allow extended control features for these sources in order to integrate them into the energy grid, an autonomous variable speed doubly fed induction generator (DFIG) based source is proposed. Modelling process of the DFIG is described ; it leads to an unified control strategy for operation on a power grid or isolated loads...
Using of MATLAB Web server (MWS) is attractive for students as well as for universities due to reduction of costs for both parties. Standard MWS applications support structured hands-on experiments welcomed for visualization of hard to grasp concepts and as a design tool. MWS applications for Math, power electronics and control design, part of a virtual laboratory created at University of Maribor,...
Due to non-linear loads or non-linear behaviour of some elements, harmonics currents are injected in the network generating a voltage distortion. To improve the voltage quality, some passive filtering are used to trap these harmonic currents. However a simple passive filter modifies significantly the characteristics of the network by generating a parallel resonance and can create some problems of...
For simulating electrical energy transducers, transient 3D finite-elements models are used. Since the behaviour of electrotechnical devices is highly influenced by the driving electrical network, such models have to be extended by circuits. This paper discusses advanced field-circuit coupling techniques, models for the coils appearing in the finite-element model and appropriate solution techniques...
This paper proposes a dead-time compensation method with a disturbance observer and a current controller for V/f control. Dead-time compensation is very important to improve motor drive performances in the low speed region. The proposed compensation method is composed in the d-q rotational frame. The ripple of the d-axis current caused by the dead-time is suppressed by an auto current regulator, the...
Switched reluctance motors (SR motors) have several desirable features, including simple construction, high reliability and low cost. But large torque ripple and expensive position sensors used in SR motor drive systems are considered as drawbacks for wide application. Several studies have succeeded in torque ripple reduction for SR motors using direct torque control (DTC) technique. In this paper,...
The direct methanol fuel cell stack appears to have great advantages since the fuel is in a liquid form. However this liquid fuel causes the corrosion in the stack and therefore has a performance drop as a result. This paper addresses some of the causes of the associated problems. It is reported that the corrosion can be limited by eliminating all metal components in the anodic liquid flow circuit;...
The design of a totally digital current control of a dc-dc switching converter has been analysed in this paper. This control consist of the prediction of the time when current inductor will reach the current inductor reference. This prediction has been obtained by means two samples of real inductor current and the application of the general equation of a straight line. This Predictive Digital Interpolation...
This paper proposes an advanced control of three-phase three-level neutral point clamped (3L-NPC) PWM converter connecting a permanent magnet synchronous generator (PMSG) to a grid. Control scheme is mainly based on active and reactive power loops and contains following additional blocks: virtual flux and filter-capacitor voltage estimators for sensorless operation, active damping (AD) of possible...
Energy management becomes more and more important with respect to rapid increasing energy costs. Exact analysis of all installed electrical loads of a company is the basic requirement for starting and realising energy-saving measures. The proposed cost-effective mobile portable measuring system is composed of a standard notebook with PCMCIA slot, a data acquisition PCMCIA card and signal interfaces...
This paper investigates the use of an imaginary power based speed estimation algorithm for induction machines. The algorithm investigated was first proposed by Peng and Fukao in 1994, and has some very desirable characteristics such as insensitivity to knowledge of stator resistance, and does not use pure integrations. However, it has been shown that the algorithm does not operate stably under regeneration...
The paper discusses modelling and simulation of power circuits. Models were used to study energy exchange and develop a control system, in particular for vehicles with regenerative braking capability. SIMULINK models were used in control system design, including the selection of circuit components for feedbacks of switched mode converters. Models of the supply circuit were designed as independent...
This paper presents the design of a small proton exchange membrane fuel cell stack to be used in uninterruptible power supply systems for remote telecommunication sites. A proof of concept design is presented using a two-cell stack made from low-cost and readily available materials. Flow plates used in the stack were manufactured from copper-clad printed circuit board (PCB) using standard PCB manufacturing...
Paper deals with automotive hybrid and power splitting drives. The system used for laboratory experiments at Czech Technical University in the Josef Bo??ek Research Center of Engine and Automotive Technology is described and its function explained. Special attention is paid to the electric power divider, which is a synchronous permanent magnet generator with separately rotating stator and rotor. The...
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