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EPE Journal Volume 14-4 - 2 - Applications
EPE Journal Volume 14-4 - 3 - Papers
- A New Single Phase AC/AC-Multilevel Converter for Traction Vehicles Operating on AC Line Voltage
- Current Control of Utility-Connected Two-Level and Three-Level PWM Inverters
- Reduction of Bearing Currents in inverter fed drive applications by using Sequentially Positioned Pulse Modulation
- Parameter Independant Phase Tracking Method for Sensorless Control of PWM Rectifiers
- Thermal Analysis of Squirrel-Cage Induction Machine
- Control Strategy for a Novel Combined Operation of Long Stator and Short Stator Linear Drive System
- Power-Electronic Interface for a Supercapacitor-Based Energy-Storage Substation in DC-Transportation Networks
EPE Journal Volume 14-4 - 1 - Editorial
By B. Sneyers
The Editorial of the EPE Journal Volume 14 N°4, "See you in 2005 in Dresden", written by Ir. Brigitte Sneyers, the Secretary General of EPE Association.
EPE Journal Volume 14-4 - 2 - Applications
By W. Leonhard
For more than a hundred years our private and public life has been advanced by two electrotechnical achievements: the instantaneous availability of practically unlimited energy and the free flow of information. They have immensely widened the range and scope of our activities: one is informed (or believes to be) allowing almost global omnipresence, at the same time they lend us forces millionfold exceeding our own.
EPE Journal Volume 14-4 - 3 - Papers
By M. Glinka; R. Marquardt
A new converter concept for direct connection to the power line of AC-fed traction vehicles will be introduced. This concept contains a new single phase AC / AC - modular-multilevel-converter (M2LC) and a concentrated medium-frequency transformer. A design for multi-system operation will be investigated that can operate on an AC 15 kV/162/3Hz as well as an AC 25 kV/50 Hz power line. The new single phase M2LC, enabling four quadrant operation, forms the core of this converter concept. The basic characteristics of this new converter will be introduced. Simulations and analytical investigations underline the attractiveness of this new M2LC converter. This versatile traction converter concept stands out due to its modularity, its superior control characteristics as well as its good adaptability to various traction drives. Therefore, the single phase M2LC has the potential to replace the conventional transformer of future AC-fed traction vehicles.
By S. M. Abu Sharkh; M. A. Abu-Sara
This paper discusses the design of a digital current controller for three-phase utility-connected 2-level and 3-level PWM inverters with output LCL filters in which the filter capacitors are connected to the dc link rails. The controller has a two-loop feedback structure, with an additional feedforward loop to compensate for utility voltage harmonic disturbance. A detailed analysis of the effect of the controller microprocessor time delay on the stability and transient response of the controller is presented. Analytical and simulation results are presented for both the 2-level and the 3-level inverter systems, demonstrating the effectiveness of the proposed controller in producing good quality current with low THD. The results confirm that using a 3-level inverter has the advantage of halving the current ripple in the filter’s main inductors, at the expense of extra inverter power devices and electronic hardware and software complexity. Experimental results for a 2-level inverter system are also presented.
By J. Zitzelsberger; W. Hofmann
The phenomenon of bearing currents is known for a long period. Especially those which are caused by magnetic asymmetries have been investigated since the beginning of the 20th century. Nowadays new kinds of bearing currents can be observed in inverter fed induction drives. Investigations done on these effects show that the switched operational mode – especially of voltage source inverters – causes a high frequency common mode voltage (CMV). This voltage supplies the common mode circuit of an electrical machine in which the bearings are a part of. Therefore, to reduce the occurrence of bearing currents it is necessary to avoid or - at least - to minimise the common mode voltage in drive applications fed by voltage source inverters. A novel principle for such a purpose is the space vector based modulation with sequentially positioned pulses (SPP). With this modulation it is possible to reduce both the number of edges within the CMV and its amplitude to a great extent without influencing the modulation index. The present paper summarises the ideas which stand behind the principle of SPP and gives an overview over the major dependences from characteristics of the drive system. Moreover, the functionality and the compatibility to standard inverter fed drives is shown by means of simulations and measurements.
By P. Szczupak; M. Linke; R. Kennel
In this paper a new parameter independent sensorless control strategy for a voltage oriented controlled (VOC) threephase pulsewidth modulated (PWM) power supply rectifier is presented. This control method requires neither the measured AC-line voltages nor any accurate circuit parameters for estimation purposes. Furthermore there is no need for additional test signals. There are no additional hardware requirements with respect to the standard drive invertersavailable in the market which usually are not equipped with AC-side voltage sensors. It will be seen that the calculation demand for the sensorless approach is negligible in comparison to the requirements for the control itself. This approach makes use of the slow varying AC-line voltage - the sample frequency of the inverter is at least ten times higher. The principle of the proposed method is explained, and its effectiveness is proven experimentally.
By O. I. Okoro
Undesirable effects such as loss of dielectrical property of the insulating material and thermal bending of the rotor and consequent loss of eccentricity among others result when the thermal limit of an electrical machine is exceeded. Due to these problems, the temperature in electrical machine must be properly monitored and specified within certain limits to reflect the mechanical, electrical and environmental conditions in which the machine will operate. This paper shows how thermal network model can be used to predict the temperatures of squirrel-cage induction machine parts at no-load and rated load. The thermal measurements carried out show that the proposed thermal model is capable of calculating the temperatures in the test machine with good accuracy during no-load and rated load operations.
By B. Yang; H. Grotstollen
To realize a highly flexible propulsion system, a combined drive of long stator and short stator linear motors is applied to operate vehicles of the NBP railway system (Neue Bahntechnik Paderborn, i.e. New Rail Technology of Paderborn in English) (Fig. 1). The control strategy of this combination is described in detail in this paper. The presented experimental results, which show the control performance, are based on extensive theoretical investigations.
[Details]
By A. Rufer; Ph. Barrade; D. Hotellier
A Power-electronic interface for supercapacitive-storage based substation in DC-transportation networks is proposed, which allows to feed as a current-source in any voltage conditions of the line. The system has been designed as a compensation-substation to be placed at weak points like end-of-line stations, and can replace supplementary feeding substations. A dedicated power-electronic converter with associated control system is proposed, for the stabilization of the voltage level at the point of coupling. Practical results are also presented, which have been recorded from a reduced scale prototype.
EPE Journal Volume 14-4 - 4 - AECCTECH_NET
By B. Sneyers
AECCTECH_NET, a network of University Laboratories and Industry R&D Laboratories to face the challenges of the European Commission's 6th and future 7th Framework Programmes.