EPE Journal Volume 09-1/2 
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EPE Journal Volume 09-1/2 - Editorial
EPE Journal Volume 09-1/2 - Papers



 EPE Journal Volume 09-1/2 - Editorial 

EPE 2001, Graz, Austria - the 9th European Conference on Power Electronics and Applications  [Details]
By H. Weiss

The Editorial of the EPE Journal Volume 09 N1/2, "EPE 2001, Graz, Austria - the 9th European Conference on Power Electronics and Applications", written by Prof. Helmut Weiss, the Conference Chairman of EPE 2001.


 EPE Journal Volume 09-1/2 - Papers 

Thermal Metrology for Power Components: Evaluation of Experimental Approaches  [Details]
By A. Bliek; J. Duveau; M.K. El Cheikh; J. Guerin; M. Tholomier

The work presented in this paper is based upon infrared (I.R.) imaging and the transient thermal impedance method. The first method provide thermal temperature resolution lower than 3C and spatial resolution close to 15 um. The I.R. experimental results are compared to the usual transient thermal impedance technique. The analysis of these methods points out the limitations of the two approaches and gives further information on the possibilities of these methods. This dual approach has been illustrated by thermal behaviour studies of bipolar power transistors and IGBT.

High Power High Frequency Soft Switching Converter Using Serial Connected Switches  [Details]
By N. Lapassat; D. Chatroux; D. Lafore; J. F. Villard

In the field of high voltage power conversion, low or medium voltage inverters are generally used with high voltage transformers. This article presents a high voltage chopper supplied directly by a high voltage source. At the same power level, higher input voltage means lower current stress in the switches, making realisation on printed board easier. Such a solution requires serial connection to realise the high voltage switch. To reach a switching frequency of several tens of kHz, MOS or IGBT are used. Serial connection of power components encounters two major problems in hard switching: voltage unbalance and overcurrents due to parasitic capacitances to ground during turn on. As the number of stages connected in series increases, those problems become more crucial.
Voltage unbalance is mainly due to differential delay time of drive circuit (switching on and off phases) and speed scattering (switching off phases). Synchronous orders and equal switching speeds are necessary to obtain a good voltage sharing. Otherwise, active clamping can be used for grid components like IGBTS. During the off-state, scattering of leakage current between semiconductors gives rise to significant voltage unbalance. Sharing resistor can be added in parallel of each switch for current unbalancing. At high frequency, they are no more needed. Parasitic overcurrents in hard commutation, for high voltage low current switches using serial connection, are one of the main problems. Soft switching can be used to reduce switching losses, voltage unbalance and parasitic overcurrents. This article presents a converter combining serial connection with soft switching.

Stability Study of the Digital Control of Induction Motor Drive Systems using Matlab (R)  [Details]
By Y. Fu; F. Labrique; D. Grenier; B. Robyns; H. Buyse

This paper deals with stability problems inherent to fully digital implementation of induction motor drive control systems. A discrete model of the current control loops has been built up by taking into account the current regulator sampling process, which allows to investigate the discrete behaviour of the current control by analyzing its characteristic roots. A program based on the proposed method has been developed in a Matlab environment. This program has been used for the discrete stability study of the current control loops of a small power induction motor and the theoretical analysis results have been confirmed by digital simulations and experimentations.

An Improved Digital Current Control of a PM Synchronous Motor with a Simple Feedforward Disturbance Compensation Scheme  [Details]
By K-H. Kim; I-C. Baik; M-J. Youn

An improved digital current control technique of a permanent magnet (PM) synchronous motor with a simple feedforward disturbance compensation scheme is presented. Among the various current control schemes for an inverted-fed PM synchronous motor drive, the predictive control is known to give a superior performance. This scheme, however, requires the full knowledge of machine parameters and operating conditions, and cannot give a satisfactory response under the parameter mismatch. To overcome such a limitation, the disturbances caused by the parameter variations will be estimated by using a disturbance observer theory and used for the computation of the reference voltages by a feedforward control. Thus, the steady-state control performance can be significantly improved with a relatively simple control algorithm, while retaining the good characteristics of the predictive control. The proposed control scheme is implemented on a PM synchronous motor using the software of DSP TMS320C30 and the effectiveness is verified through the comparative simulations and experiments.

Performance Comparison of Standard and optimised Clamp Diodes for High Power IGBT Inverters for Traction Applications  [Details]
By F. Profumo; A. Tenconi; S. Facelli; B. Passerini; L. Fratelli

In this paper the problem of overvoltages protection in high power IGBT inverters for traction applications is presented. The turn off operation of the voltage clamped IGBT inverter is described. The capability of the clamp circuit in limiting the IGBT turn-off voltage spikes is analysed and the importance of the clamp diode electrical characteristics are pointed out. Finally, experimental and simulated results allow a direct comparison between standard ultrafast clamp diodes and optimised clamp diodes.

Flux, Position and Velocity Estimation in AC Machines at Zero and Low Speed via Tracking of High Frequency Saliencies  [Details]
By P. L. Jansen; M. J. Corley; R. D. Lorenz

Achieving transducerless (sensorless) control of a.c. machines that is robust during sustained operation at or near zero speed (i.e. zero excitation frequency) is exceedingly difficult. This paper present an elegantly simple and viable, generalized approach to achieving robust, accurate transducerless state estimation in polyphase a.c. machines, including the estimation of flux, position and velocity in induction and synchronous machines at zero and low speeds. It is based upon the tracking of magnetic saliencies via inverter-generated high-frequency signal injection with demodulation incorporating heterodyning and a closed-loop observer. The saliencies may be saturation-induced, thus yielding a means of direct flux position estimation, or rotor-constructed and thus yielding rotor position and velocity estimation. Experimental results are provided demonstrating rotor position estimation with a permanent magnet synchronous motor.

Analysis of Rectifier Failure to Power Line Transients  [Details]
By M.L. Sudheer; M.K. Gunasekaran

The current trend of electronic industry is towards the manufacture of high power factor equipments, which increases the power quality of a.c. utility. These equipments have to be connected directly to a.c. utility, hence they should be immune to power line disturbances, especially the transient disturbances. The high-energy transients can cause component destruction or overheating and deterioration. Front-end rectifiers may be completely destroyed by such transients during their normal working. This paper presents one such voltage transient, which destroys a diode in the front-end rectifier and gives a procedure to select protective component to prevent such destruction that can be adopted in common designs. A curve for selecting the protective component against such transients is also presented.

Three-Phase Battery Charger for Electric Vehicle  [Details]
By B. Chauchat; S. Bacha; M. Brunello; J-P. Ferrieux

The battery chargers for electric vehicle (E.V.) are on-board devices in the case of normal charge. their power level is included in a range from 3 to 6 kW, corresponding to the 16 A or 32 A single-phase plug. After cost, size and weight are the most important criteria. In order to improve these three characteristics, integrated chargers have been developed. This solution re-uses the main converter of the drive train as an AC-DC converter, relying on the motor windings as inductors. No further component is required. This integrated charger has been studied and developped for a 6 kW power level from the single-phase 230 V / 32 A mains. Power factor correction, as well as d.c. current control over a wide range of voltage battery levels are obtained.
The study presented in this paper proposes the analysis of the three-phase converter for integration into EVs. In this case, available power up to 18 kW allows the charge time to be reduced. Two solutions are presented for the battery voltage matching. Onj one hand the control of the reactive power is analyzed in order to avoid an additional tansformer. On the other hand, the three-phase structure with transformer is presented along with experimental results. Owing to this structure, power level is higher than a conventional charger with a simplified system: the on-board part is integrated to the drive train and the fixed part is reduced to a simple transformer.