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EPE Journal Volume 13-2 - Papers
- Low Profile Switchmode Converter with Embedded Passive Components in the PCB
- Digital Control in Multi-Phase DC-DC Converters
- Simple Direct Power Control of Three-Phase PWM Rectifier Using Space Vector Modulation - a Comparative Study
- A Space Vector Based PWM Method Using Only the Instantaneous Amplitudes of Reference Phase Voltages for Three Level Inverters
- Experimental Assessment of the Non-Characteristic Harmonics Generated by Adjustable Speed Drives
EPE Journal Volume 13-2 - Editorial
By B. de Fornel
The Editorial of the EPE Journal Volume 13 N°2, "EPE 2003, Toulouse, France. A large and friendly meeting for industrial and academic people in Power Electronics", written by Prof. Bernard de Fornel, the EPE 2003 Conference Chairman.
EPE Journal Volume 13-2 - Papers
By J.A. Ferreira; E. Waffenschmidt
Technologies are now available to embed circuit functionality into the printed circuit board (PCB) that is used to interconnect the various components of a power electronics converter. Technologies are presented for realizing capacitive, magnetic and resistive functions in a multilayer PCB. It is suggested that in planar magnetic cores be combined with ferroelectric capacitor sheets together with new surface mount components to enhance the reactive power capability of the passive components. Two case studies are presented illustrating the possibilities that the new technologies offer. The capacitance values needed for switchmode power conversion is analyzed and possibility to embed these capacitors in the PCB is investigated. Two factors that limit the power handling capability in low profile converters with embedded passive components are identified and analyzed, namely the ratio of PCB area to component area and role that the third dimension plays in planar converters.
By A. De Castro; P. Zumel; O. Garcia; T. Riesgo
Multi-phase power converters are especially used in applications such as mobile equipments, VRM or automotive power supplies. This is due to their advantages, like increased output current capability, better thermal management, improved dynamic response, reduced EMI and harmonics, and smaller input and output filters. As a consequence, the design space can be re-explored using multi-phase converters. In this work, digital controllers are proposed for multi-phase converters. They provide advantages that are especially important for these converters and overcome problems difficult to solve with analog controllers. Some of the digital control advantages are capability for managing a large number of driving signals, accurate duty cycle generation, and easy phase-shifting of the driving signals. The proposed controller is based on custom hardware, like Field Programmable Gate Arrays (FPGA), for taking advantage of its concurrent operation in order to generate all the driving signals. The experimental results show the feasibility of the method, opening interesting possibilities in the control of state of the art power converters.
By M. Malinowski; M. Kazmierkowski
This paper describes control techniques for PWM rectifiers. In particular, the so-called virtual-flux oriented control (VFOC) and virtual-flux based direct power control (VF-DPC) schemes are described and compared with their voltage based counterparts, that is, the voltage oriented control (VOC) and voltage-based direct power control (DPC) techniques. Theoretical background is provided, and results of computer simulations are given, documenting advantages and disadvantages of the individual control strategies. Moreover, paper proposes a novel and simple direct power control of three-phase PWM rectifiers with constant switching frequency using space vector modulation (DPC-SVM), which combines VFOC with VF-DPC. The steady state and dynamic results of DPC-SVM that illustrate the operation and performance of the proposed system are presented. It is shown that DPC-SVM exhibits several positive features as: simple algorithm, good dynamic response, constant switching frequency and particularly provide sinusoidal line current when supply voltage is no ideal. Results have proven excellent performances and verify the validity of the proposed system.
By M.R. Baiju; K. Gopakumar; V.T. Somasekhar; K.K. Mohapatra; L. Umamand
This paper presents a space vector based PWM method for the 3-level inverter. The three level inverter space phasors are located in 19 locations forming 24 sectors. The instantaneous reference space phasor is generated by switching between the three vectors forming the sector in which the tip of the reference vector lies. The proposed PWM method does not require the sector identification and look up tables to select the appropriate vectors. The inverter leg switching times are directly obtained from the instantaneous reference phase voltage amplitudes and the inverter switching vectors are automatically generated . The inverter leg switching times and the appropriate vectors are obtained using an algorithm, which does not involve computations like square root or coordinate transformations. The proposed method is implemented on a 1hp induction motor drive and the experiment results are presented.
By M. Contreras; H. Calleja
Adjustable speed drives (ASD) are widely used in industry. A typical voltage-source ASD is comprised of a three-phase rectifier, a low-pass filter and an inverter stage, as shown in Fig. 1. This figure also shows, from left to right, the typical current waveforms at the a.c. input, the d.c. link, and the output. An important issue in this kind of apparatus is the harmonic content in the current drawn from the a.c. line, since the maximum amplitudes that can be tolerated are tightly regulated by standards. It is a common practice to analyse the harmonic generation considering isolated stages but, due to the complexity of the expression involved, the analysis is performed under several simplifying assumptions. Quite often, however, the analysis fails to predict accurately the harmonic content obtained in a particular application. Especially troublesome are the so-called non-characteristic harmonics (that is, harmonics whose frequency is not an integer multiple of the mains frequency). For example, harmonics related to the output waveform that propagate through the filter, to the mains. This paper is aimed at the experimental investigation of the non-characteristic harmonics generated by a typical voltage-fed ASD. The investigation is performed taking into account parameters such as the modulation index and the low-pass filter cutoff frequency. Three different cases are considered: a single ASD, two inverters sharing the same d.c. bus, and two ASD’s connected to the grid at the same point. The test performed show that, although the generation of non-characteristic harmonics does occur, in most cases the amplitudes involved are small. An exception to this occurs when the low-pass filter has not been properly designed, or the supply is unbalanced.