EPE Journal Volume 23-3 
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EPE Journal Volume 23-3 - Editorial
EPE Journal Volume 23-3 - Papers



 EPE Journal Volume 23-3 - Editorial 

Editorial  [Details]
By Brigitte Sneyers
Editorial of EPE Journal Volume 23-3, written by Brigitte Sneyers, Secretary General, EPE Association


 EPE Journal Volume 23-3 - Papers 

Electro-Thermal Behaviour of a SiC JFET Stressed by Lightning Induced Over-Voltages  [Details]
By Dominique Bergogne; Cyril Buttay; Rémi Robutel; Fabien Dubois; Rémy Ouaida; Hervé Morel
SiC JFETs are experimentally tested to verify their robustness against lightning induced strokes. The experimental setup is fully described. A lightning surge generator is built and a SiC JFET is stressed. The full thermal response of the SiC JFET internal temperature is obtained from an specific temperature estimation technique at different time steps during the surge test. This short time thermal response is compared and validated by a conventional 1D thermal model. This work shows that for a moderate lightning stroke, according to standards [1], the JFET temperature rise is less than 60 °C, which is acceptable in most circumstances.

Nearly Constant Switching Frequency Hysteresis Current Controller with Fast Online Computation of Boundary for a 2-Level Induction Motor Drive  [Details]
By Anubrata Dey; K Mathew; K Gopakumar; Marian P. Kazmierkowski
A nearly constant switching frequency current hysteresis controller for a 2-level inverter fed induction motor drive is proposed in this paper. The salient features of this controller are fast dynamics for the current, inherent protection against overloads and less switching frequency variation. The large variation of switching frequency as in the conventional hysteresis controller is avoided by defining a current-error boundary which is obtained from the current-error trajectory of the standard space vector PWM. The current-error boundary is computed at every sampling interval based on the induction machine parameters and from the estimated fundamental stator voltage. The stator currents are always monitored and when the current-error exceeds the boundary, voltage space vector is switched to reduce the current-error. The proposed boundary computation algorithm is applicable in linear and over-modulation region and it is simple to implement in any standard digital signal processor. Detailed experimental verification is done using a 7.5 kW induction motor and the results are given to show the performance of the drive at various operating conditions and validate the proposed advantages.

A Simplified and Fast DSP-CPLD-Based Implementation Method of Space Vector Modulation Applied in Indirect Matrix Converters  [Details]
By Alireza Jahangiri; Ahmad Radan
This paper proposes a new switching implementation scheme for an Indirect Matrix Converter (IMC) that can be suitably implemented using a low-cost 32-bit fixed-point DSP (TMS320F2812) operating at 150 MHz and a functional digital logic programmed in Altera (EPM7128s). The proposed method is based on carrier based PWM signals, has less computational complexity and can be implemented with very high speed and resolution. Simulation and experimental results obtained from a 5 kW converter are shown to support the given theoretical analyses and verify the full functionality of the proposed scheme.

An FPGA Controlled DC/DC Step-Up Converter for Automotive Applications  [Details]
By Marcello Chiaberge; Gianluca Botto; Mirko De Giuseppe
Piezoelectric injectors allow to inject precise proportional quantities of fuel at extremely high speed. Controlled by pulses from the engine management unit, they work like solenoid valves, opening and closing back very rapidly, spraying the exact quantity of fuel determined by the injection computer into the engine combustion chambers. However, for this type of injectors an impulse of a hundred volts is applied in order to actuate them. This is a big concern in automotive environment, where the 12 V battery voltages is still the main power source available. Therefore, a power converter is needed to interface battery voltage and piezo actuator; for mechanical and electrical reasons (weight, dimensions and power losses) a switching amplifier is preferred with respect to linear amplifier, especially for this type of applications where efficiency and weight are the main issues. Fig. 1 presents a switching amplifier for piezo actuator: it consists of two components, a unidirectional DC/DC converter with a small input power that loads a large buffer capacitor and a bidirectional DC/DC converter, which controls the energy alternating between the buffer capacitor and the piezo actuator. The requirements on the unidirectional DC/DC converter are few. It only needs to compensate for the power losses of the two stages plus the energy dissipated in the actuator and the connected mechanical system [6]. Conventional DC/DC boost converter is not the best solution in piezoelectric based applications where a high step up ratio (more than 20) and high efficiency power conversion is required. Flyback converter could be an alternative topology but presents high switching losses and it has an insulated output, so not compliant with electrical load specification. An efficient high-step up DC/DC converter is presented for interfacing the standard 12 V battery with the high voltage DC-bus used for piezoelectric actuators system. In the proposed converter, two coupled inductor boost converters are interleaved and controlled by an FPGA. Different types of control techniques could be used to limit the input current [7]; the solution presented herein allows fast transient response and best performances with respect to traditional control techniques. Moreover the implemented technique has the advantages of lower electromagnetic emission and higher operating frequency capability, compared to the standard fixed frequency control; on the other hand it is difficult to design the EMI filter due to the intrinsic variable frequency. The high computational load of the control algorithms forces the use of an FPGA implementation in order to achieve the desired accuracy in real time control at the frequency of the PWM signal needs for the DC/DC converter, which will be 200 kHz. Design and analysis of the proposed converter are presented. Finally, experimental results are reported in order to validate the proposed converter.

Mission Profile Based Optimization of a Wearable Power System  [Details]
By Ivana F. Kovacv evic; Johann W. Kolar; Simon D. Round; Miroslav Vasic
A Wearable Power System (WPS) is a portable power source utilized primarily to power the modern soldier’s electronic equipment. Such a system has to satisfy output power demands in the range of 20 W...200 W, specified as a 4-day mission profile and has a weight limit of 4 kg. To meet these demands, an optimization of a WPS, comprising an internal combustion (IC) engine, permanent magnetic three-phase electrical motor/generator, inverter, Li-batteries, DC-DC converters, and controller, is performed in this paper. The mechanical energy extracted from the fuel by IC engine is transferred to the generator that is used to recharge the battery and provide the power to the electrical output load. The main objectives are to select the engine, fuel and battery type, to match the weight of fuel and the number of battery cells, to find the optimal working point of engine and to minimize the system weight. To provide the second output voltage level of 14 VDC, a separate DC-DC converter is connected between the battery and the load, and optimized for the specified mission profile. A prototype of the WPS based on the optimization presented in the paper results in a total system weight of 3.9 kg and fulfils the mission profile.