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EPE Journal Volume 17-3 - Papers
- Dual Channel Resonant DC-DC Converter Family
- A New ZVT Power Factor Corrected Three-Phase AC-AC Converter with Single-Phase HF Link
- A Saturable Transformer Based Approach to Drive a Synchronous Rectifier
- Experimental Simplex-Genetic Algorithm for Self-Commissioning of Electric Drives
- Stability of Voltage and Frequency Control in Distributed Generation Based on Parallel-Connected Converters Feeding Constant Power Loads
EPE Journal Volume 17-3 - Editorial
By Krzysztof Zawirski
Invitation to EPE-PEMC 2008 in Poznan, Poland, 13th International Power Electronics and Motion Control Conference, written by Krzysztof Zawirski, EPE-PEMC 2008 General Chairman
EPE Journal Volume 17-3 - Papers
By J. Hamar; B. Buti; I. Nagy
The paper gives an overview of a novel resonant DC-DC converter family. The common feature of the configurations belonging to the family is that the energy is transmitted through two channels from the input to the output using one or two switched capacitors. The configurations can have one or two input and one or two output voltages. Due to the two channels their applications are recommended in the medium or higher power ranges. Advantages of the converters are that they have buck, boost and buck & boost version and they can work in soft-switched mode too. Drawbacks are the higher number of main components, and the lack of potential isolation between input and output in their basic configurations. The main objective of the current paper is to present the twelve configurations of the family and to discuss the operation of six of them. The considerations are verified by simulations and test results.
By A. J. Sabzali; T. H. Abdelhamid
This paper presents a new zero-voltage transition (ZVT), power factor corrected three-phase a.c.-a.c. converter with single-phase high frequency (HF) link. It is a two-stage converter; the first stage is a boost-integrated bridge converter (combination between 3-ph boost converter and a bridge converter) operated at fixed frequency and operates in two modes at ZVT for all switches and establishes a 1-ph square wave HF link. The second stage is a bi-directional pulsewidth modulation (PWM) 3-ph bridge that converts the 1-ph HF link to a 3-ph voltage using a novel switching strategy. The converter modes of operation and key equations are outlined. Simulation of the overall system is carried out using Simulink. The switching strategy and its corresponding control circuit are clearly described. Experimental verification of the simulation is carried out for a prototype of 500 W at 100 V, 10 kHz HF link.
By F. Tourkhani
This paper presents a new and an improved approach for driving a synchronous rectifier (SR) in a switching power converter. This approach consists to use a saturable transformer (ST) in series with a synchronous rectifier to detect the synchronous rectifier transition at turn off. The saturable transformer generates a very narrow signal (100 ns to 200 ns) at turn OFF when the current in the synchronous rectifier reaches zero. This signal will be used by the gate drive circuit to drive the synchronous rectifier at turn off. The saturable transformer approach presented in this paper is topology independent and it can be applied to any power converter. In addition, it offers the possibility of parallel connection of power converters without the risk of power sinking. The two-switch forward power converter with two synchronous rectifiers has been implemented to test the functionality of the synchronous rectifier driving method. In this experimental prototype, the input voltage is equal to 100 V, the output voltage is equal to 9 V and the output load is 20 A. At the 180 Watts output load, the minimum measured efficiency was 93 % at 9 V.
By G. L. Cascella; N. Salvatore; L. Salvatore; M. Sumner
This paper deals with the self-commissioning of electric drives. To improve the performance of the available industrial drives, an on-line auto-tuning based on a hybrid genetic algorithm is proposed. This strategy integrates the simplex method, local searcher, in a genetic framework, global searcher, in order to speed up the convergence. Moreover it is very reliable because experimentally tests each possible solution and consequently the final result is not affected by the accuracy of the motor model. Finally, the proposed on-line hybrid optimization can be embedded as a fully-automated tool without any extra-hardware on industrial drives. Extensive experimental results prove the effectiveness of the proposed approach not only in comparison with conventional commissioning, but also when compared with further accurate handcalibration.
By P. Karlsson; J. Björnstedt; M. Ström
In this paper stability and dynamic properties of voltage and frequency droop control of power electronic converters are investigated for a distributed generation system. Droop control is utilized to share active and reactive power among the source converters. The voltage and frequency controllers are designed so that stand-alone converter operation feeding constant power loads performs satisfactory. These controllers are adapted to mimic the behaviour of present rotating generators connected directly to the power system, for seam-less transfer between island and grid-connected modes of operation. The target system for the analysis is a stand-alone system to which three power electronic converters and one rotating generator could be connected (Fig. 1). Small-signal and switch-mode, time-domain simulation results of a threeconverter distributed generation system facilitating stand-alone operation verify the operation. Simulation and experimental results of a three-converter stand-alone system, with and without a rotating generator present, are also included for verification.