EPE Journal Volume 07-1/2 
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EPE Journal Volume 07-1/2 - Editorial
EPE Journal Volume 07-1/2 - Papers



 EPE Journal Volume 07-1/2 - Editorial 

EPE '97 is over, let's meet in Lausanne at EPE '99  [Details]
By B. Sneyers

The Editorial of the EPE Journal Volume 07 N°1/2, "EPE '97 is over, let's meet in Lausanne at EPE '99", written by Ir. Brigitte Sneyers, the Secretary General of EPE Association.


 EPE Journal Volume 07-1/2 - Papers 

Standard and Shorted Anode Non-Punch-Through Emitter Switched Thyristors  [Details]
By D. Flores; P. Godignon; M. Vellvehi; J. Fernández; S. Hidalgo; J. Rebollo; J. Millán

This paper is aimed at the analysis of the electrical characteristics of non-punch-through EST structures. The operation mode and the transient process are studied by means of 2D numerical simulations. Standard and shorted anode test structures were fabricated with a conventional IGBT process technology, and their characteristics are compared with those of IGBT abd BRT structures. It is shown the improvement of the EST turn-off time when including the shorted anode structure, and the dependence of the maximum controllable current on the device geometrical dimensions.

A New Measurement Technique for the Conductivity Mobility Versus Injection Level in Silicon  [Details]
By S. Bellone, G. V. Persiano; A. G. M. Strollo; S. Daliento

Modelling mobility degradation due to carriier-carrier scattering is of utmost importance for the analysis and simulation of power bipolar devices. Unfortunatelly, there is a large disagreement among the several theoretical mobility models available in literature. In addition, the experimental approaches proposed up to date for mobility extraction are based on measurements performed on thick p-i-n diodes, resulting in large power dissipation with significant device heating and rough estimation of injection level.
In this paper we present a new approach to measure the conductivity mobility dependence on the injection level, based on electrical measurements performed on a three-terminal test structure. The new technique overcomes most of the intrinsic limitations of previously proposed approaches and has the unique capability of extracting the injection level dependence of both hole and electron mobilities.
Two-dimensional numerical simulations and experimental results obtained both on n-type and p-type specimens are presented and compared to existing analytical mobility models.

Optimisation of 1000 V Epitaxial IGBT Device for a 2 kW Zero Current Resonant Converter  [Details]
By L. Fragapane; R. Letor; F. Saya

The use of epitaxial IGBT in ZCQR (Zero Current Quasi Resonant) Converters needs the optimisation of both the device structure and of the working conditions.
The most critical issue is the life time of minority carriers in the epitaxial layer which involves a trade-off between static and dynamic performances of the IGBTs.
A correct design of the converter contributes also improving the working condition of the IGBT so reducing the switching losses.
This paper investigates methods of reducing IGBT power losses in a ZCQRC and shows how a correctly adjusted lifetime makes a 1000V epitaxial IGBT suitable for operation at high current and high frequency.

Resonant Converter for Automatic Inductive Charging  [Details]
By R. Laouamer; O. Frölich; M. Brunello; J. P. Ferrieux

Battery charging of electric vehicles is by far one of the most crucial issues facing potential EV automobile manufacturers. Two charging techniques for EVs have been proposed: conductive charging where the transfer of energy is done by ohmic contacts, and inductive charging where magnetic induction is used for energy transfer. This paper will address inductive charging technology. Important advantages of inductive charging include the elimination of exposed conductors, improved life duration of charger at high currents and transformer isolation which gives a safety edge over conductive techniques. In addition, inductive charging makes it possible for the interface to operate over wide range of power levels and frequencies with the same on board charging port.

A PWM Rectifier Bridge with Unity Power Factor for High Current Source Applications  [Details]
By X. Pierre; J. P. Cambronne; M. Provoost

To obtain a current source with high voltage and high current from a single phase supply, a solution is a series-connection of two thyristor bridges. In spite of a sequential control of the converters, the power factor of the system remains low because of the consumed reactive power inherent to thyristor structures and because of the harmonic content of the input current. Nevertheless a power factor improvement of this structure is possible when using semiconductors with turn-off capabilities associated with PWM control and power filters. Subsequently different control strategies are considered in this paper as they are determinant for both the filters rating and the overall efficiency of the system.

4000 V - 300 A Eight-Level IGBT Inverter Leg  [Details]
By P. Carrčre; T. A. Meynard; J. P. Lavieville

The application field of the 1200 V IGBT devices is usually limited to a dc-link voltage up to about 600 V. In order to extend this field, new structures have been developed. In this paper, an inverter leg made of seven nested cells is presented. With this structure, it is possible to increase the d.c.-link voltage of IGBT inverter up to 4000 Vdc and provide a 300 Arms current. Moreover, the output waveforms fully benefit from the increased number of switches.

A New Monophase Multilevel Rectifier: Structure and Control  [Details]
By P. Bartholoméüs; P. Le Moigne

One of the most important cares of the power electronic designer is the reduction of the harmonics created by converters. These harmonics are attenuated by passive elements whose size is directly linked to the frequencies which have to be filtered. For this reason, the technique of Pulse Width Modulation (PWM) is widely used. This principle of modulation does not lead to a reduction of the harmonic distortion factor (THD) of the waveform directly generated by the converter (it even leads to a slight increase of it [1]) but it permits an increase of the frequency of the disturbing harmonics. In this way the size and the weight of the filters associated to the converters can be reduced.
Unfortunately this method introduces some problems: switching losses become more and more important when the frequency increases. So it is necessary to use faster electronic components to obtain quicker commutations. But this choice leads to the generation of very high frequency EMI, due on one hand to quick variations of the electrical values during the commutations [2] and on the other hand to high frequency working [3]. Nowadays these EMI can not be tolerated because of the new EMI standards.
In order to overcome these constraints (without any increase of the filter size) multilevel converters can be used. Actually the converters of this kind are known to generate less harmonics than the classical ones [4]. So it is possible, using multilevel techniques, to reduce the THD of the PWM waveform when an increase of the modulation frequency is not possible anymore.
Unfortunately, as the number of levels increases, the structure becomes more and more complex. This is a drawback which can be lowered in the case of rectifiers: as the bipolar energy flow is needed, structures can be simplified.
This paper deals with a new non-reversible monophase multilevel rectifier using Pulse Width Modulation and drawing up a sinusoidal and in phase mains current [5, 6]. Its working and the constraints involved by this choice are defined. Afterwards, the particular voltage balancing loop and the process of generating semiconductor control signals are studied with the help of a formalism developed in our laboratory [7]. Finally the experimental results, obtained with a 3 kW prototype, confirm the simulation of the model and validate this study.

Energy Absorption Devices for Solid State Interruption  [Details]
By J. M. Li; S. Tian; D. Lafore

A solid state contactor or circuit breaker consists of three main elements: a low on-stage voltage main power semiconductor, an energy absorption device (ZnO varistors in general) and a snubber ("C" or "RCD") which is only necessary for power devices having limited RBSOA. ZnO varistors have high peak current and energy absorption capabilities. However, they give not only high clamping factor but also voltage spike at the beginning of clamping, thereby greatly increasing the requirement in main power switch breakdown voltage. In this paper, we propose an active energy absorption device which allows controllable clamping factor and constant clamping voltage and does not have the ZnO's voltage spike. Therefore it can be another alternative for energy dissipation in solid state interruption. The proposed device can also be associated with ZnO varistors to achieve a combined device, enabling high clamping performance as well as high energy dissipation capability.

Vector Control of Induction Motor with Split Phase Windings  [Details]
By K. Gopakumar; V.T. Ranganathan; S. R. Bhat

A vector controlled scheme is described for an induction motor with split phase windings. Such a motor is obtained by splitting the phase windings of a conventional three phase motor with an angular seperation of 30 electrical degrees between the axes of the two halves. In the proposed scheme the motor is run as a three phase machine by connecting the split phase windings in series. An appropriate split phase induction motor model based on space phasor notations is proposed. From this space phasor model of the split phase machine, a simple technique for measuring the equivalent circuit parameters for the motor is presented. Based on the proposed model a method for acquiring the position of the rotor flux is developed. The scheme is based only on the voltage and current measurements, without the need for position encoders. It is also independent of machine resistance values. Results from computer simulation as well as from an experimental prototype drive are presented and discussed.

Influence of Switching Frequency and Squirrel Cage Design on Audible Noise and Losses in Induction Motor Drives  [Details]
By S. Van Haute; A. Malfait; R. Belmans

A large number of experiments are performed to analyse the influence of the inverter type and the switching frequency on the audible noise, losses and overall efficiency in induction motor drives. Temperature measurements both in stator and rotor give an indication of the required derating, if any. Results for a standard design motor, consecutively supplied by a transistor based inverter and IGBT inverter are compared with the behaviour when the machine is directly connected to the mains. To analyse the influence of the rotor design, a special rotor with no current redistribution is constructed and mounted in a rewound stator. Higher switching frequencies have a large influence on audible noise and temperature, but the overall efficiency remains nearly constant. However the distribution of losses is influenced.