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EPE Journal Volume 10-3/4 - Papers
- An Intelligent Neuron-Ship-Based Fluorescent Lamp Ballast for Indoor Applications
- Analysis and Design of a New Switching Power Amplifier
- A New Current Control Strategy for Three-Phase Rectifiers
- Asynchronous Motors in Electric Traction
- A New Transformerless Topology for AC-FED Traction Vehicles using Multi-Star Induction Motors
- Control System for a UPFC in a Transmission Line
- Multi Agent-Aided Tools for Engineering System Design: a Case Study
EPE Journal Volume 10-3/4 - Editorial
By B. Sneyers
The Editorial of the EPE Journal Volume 10 N°3/4, "Some insights in past and future power electronics events", written by Ir. Brigitte Sneyers, the Secretary General of EPE Association.
EPE Journal Volume 10-3/4 - Papers
By J. M. Alonso; J. Ribas; A. J. Calleja; E. López; M. Rico
A new intelligent ballast implemented around a Neuron Chip control circuit is presented in this paper. Power factor correction (PFC) and resonant inverter (RI) stages are used to supply the lamps. Switching frequency is controlled directly from the Neuron Chip I/O port, allowing to implement soft-igniting and dimming strategies. Communications through the power line are also included using a special power line transciever. The ballast constitutes a complete intelligent node able to operate in Local Operating Networks (LON).
By M. El-Habrouk; M. K. Darwish; P. Mehta
This paper presents a new switching power amplifier suitable for testing equipment such as computers, lighting and rotating machines with non-sinusoidal voltage waveforms and with specific harmonic content. the proposed system overcomes the disadvantages inherent in existing techniques, which are briefly reviewed. The detailed analysis and design together with the results of simulation studies and experimental work are also included.
By L. Marroyo; H. Piquet; P. Sanchis
Natural coupling between phases in three-phase rectifiers with sinusoidal current absorption when the neutral point of the mains is isolated induces a voltage between this neutral point and the rectifier d.c. link midpoint. As it is shown in this paper, this voltage has a crucial importance on the system robustness, especially when it has to face different kinds of disturbances. However, classical current control strategies never control this voltage. In this paper, a new control philosophy is proposed. With this control strategy, two of the three freedom degrees are used to control the three phase currents and the third one allows the voltage between the mains neutral point and the d.c. link midpoint to be controlled. The obtained performance and robusness are shown much better.
By G. Montessori
In many applications, the motor must posses a high overload capacity: That is particularly necessary in electric traction, in lifting gears and in various industrial applications.
Initially either d.c. motors were employed with series excitation, able to assure high working flux value and to produce high torque, or d.c. motors with shunt excitation in which the armature reaction is compensated by auxiliary poles. Some time ago, flux value requirements in the motors were obtained by resorting to excitation with permanent magnets having high coercitive force, both in d.c. motor and in asynchronous motors (brushless motors), giving the possibility of obtaining a torque of the order of 4 times the nominal value of the motors.
The asynchronous motor has always represented the ideal motor for its robustness, reliability besides its low cost, but for a long time it was considered unsuitable for traction applications because of its difficulty to support overloads. The vector control type inverter has increased its performance but, because of its high dependance on the motor parameters value and stability, it is not suited to applications requiring a torque 1.5 to 2 times higher than the nominal value.
Using the vector control it is still necessary to resort to gear changes in the electric passengers car or to over dimension motors in industrial trucks.
The new DFC* system presented in this article is based on a choice of variables and of control systems so to avoid any dependance on motor parameters and it is suited to any overload. In DFC the constancy of rotoric flux is particularly observed in every condition of speed and load. The response illustrated in figure 1 is obtained. We note the perfectly linear increase of torque with slip. We see the advantage of this condition in respect to the cases of flux constancy in airgap and in the input. The performance of DFC is superior to that of Brushless motor not having physical limit to the maximum torque value nor magnetization problems. The asynchronous motor required is much more reliable and cheaper than brushless.
By M. Steiner; R. Deplazes; H. Stemmler
Conventional traction vehicles for a.c.-mains contain a line-transformer in the propulsion chain. This transformer, especially for 15 kV/16.7 Hz main lines, is bulky, expensive and has high losses. This paper proposes a completely new transformerless configuration which reduces weight and dimensions of the drive power chain and improves the efficiency. On the line side, series connected voltage source inverters are connected via a line choke to the overhead line. This leads to d.c.-links on different voltage potentials, which ask for a new motor concept. The proposed 3-star induction motor with three independant 3-phase windings is fed by three 3-phase inverters on different voltage potentials. A new control structure for this 3-star induction motor becomes necessary and is proposed.
By A. García-Cerrada; P. García-González
This paper focuses on the control of the power flow through a transmission line using a PWM-based UPFC. The dynamic model of the UPFC has been developed using the space-vector representation of the instantaneous three-phase variables. The Park's transformation and the reference frame selected reduce the control of the real- and reactive-power flows to the control of the d- and q-axis currents, respectively. The proposed control scheme produces fast and decoupled response of the real- and the reactive-power flow through a transmission line. The system performance has been simulated under normal operation condition and under fault conditions. A 15 kVA prototype with 750 Hz switching frequency has been build to illustrate the main contributions. Experimental results agree with the theoretical analysis and the simulation results. Finally, the bandwith of the UPFC has been characterised. The theoretical closed-loop transfer function agrees with the experimental one. It is shown that the bandwith of the UPFC is high enough to damp the main perturbations of a power system. Under fault conditions in a typical scenario, power system oscillations can be damped quickly with the UPFC.
By D. Fezzani; J. Desbiens
This paper will be available soon. - This paper introduces key-features of a multi-agent prototype, which is integrated in a well-known approach of development of distributed artificial intelligence tools, and constitutes the first stage of our effort towards a multi-agent system for designing engineering applications and especially power electronic converters. The design needs a high level of expertise and requires the cooperation of several multidisciplinary groups. In order to ensure the coordination of the design activities of these groups, we associate each expert that participates in designing the power circuit with an agent, which substitutes this expert and will simulate his reasoning. To manage communications between agents, we have chosen a Java implementation of the Actor model, called Epidaure, which constitutes an environment where communications are done via message passing. This paper will give an outline of some artificial intelligence applications. Emerging theories in the area are also reviewed. This paper will present more particularly the aspect of the agent structure and reasoning process, and will show how a decentralized organisation with simple communication is a reasonable trade-off between a centralized architecture and the use of global knowledge.