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International audience; The influence of the electromagnetic environmentof the indoor power line grid (Houses’ Power Grid) isincreasingly important on the Power Line Communicationtransmission. The household equipment operating changesconsiderably the network impedance. Several procedures exist toevaluate the network impedance. Two impedance measurementtechniques seem to be the most adequate and allow tocharacterize loads under their operating conditions. The first oneuses current injection and reception probes and the second oneuses capacitive coupling. With a proper pre-measurementcalibration process, the proposed methods allow to measure theevolution of the impedance versus frequency of the active loads(TV screen, Fluorescent lamp…). This study deals with theanalyses of these two methods in order to evaluate theiradvantages and disadvantages. The measurements are carried innarrowband and broadband in the frequency range of 10 kHz to100 MHz.

In this study, RLCG method is used to estimate a low voltage transmission line for twisted overhead and underground low voltage distribution cables. This model is applied for cables with different types, different sections and lengths taking account the capacitive and the inductive coupling. SPICE determination of transmission characteristics and cables crosstalk are validated throughout physical measurements. Line attenuation of a proposed architecture in low voltage distribution network is also evaluated. The full system is implemented using the cable transmission line of the different branches present along the line and loads connected to the network.

International audience; Broadband power-line communication (PLC) technologies are one of the main parameters of digital convergence voice-data-video in the home environment. These technologies use the power-line network as a propagation and a communication medium. Its transmission quality depends on the frequency behavior of the propagation medium and the connected household electrical appliances. The impedance of those devices and noise levels has a great impact on the PLC systems. In this paper, a simulator for indoor power-line channels is presented. In this paper, a new approach is presented for modeling temporal variations of noise and channel on indoor power lines. A three-conductor power cable (phase, neutral, and ground) is modeled by a circuit of four elements (resistor R, inductor L, capacitance C, conductance G). The RLCG parameters are deduced from the impedance measurement in open circuit and in short circuit. The cable model is validated in time and frequency domains. Then, the temporal variation of periodic noise is modeled by a stochastic approach. The global model, combining both channel and noise variations, is validated by comparing SPICE simulation and measurement results.

Spread spectrum clock generation techniques were originally developed to reduce electromagnetic interference (EMI) in communications and microprocessor systems working in the range of hundreds of megahertz. Nowadays, the switching frequency of power converters has been increasing up to values that make worthy the application of such switching frequency modulation techniques to reduce EMI emissions in power converters. Although random modulations have been applied before to power converters, periodic patterns can provide some advantages. First, theoretical principles of frequency modulation using three periodic patterns for the modulating function are presented. The influence of some important modulation parameters on the EMI reduction is analyzed and some considerations about the EMI filters design are also presented. The effectiveness of such methods in terms of EMI reduction is demonstrated theoretically and confirmed with experimental results obtained from tests carried out on two converters. The first one is a 2.5 W buck converter that can be switched up to 1 MHz and the second one is a 600 W boost converter switching at 40 kHz. In both cases, attenuations obtained in conducted EMI are evaluated. Finally, special attention has been paid to input current and output voltage ripple in order to evaluate possible undesired side-effects produced by this technique.

International audience

In this paper we present how the design of a power converter can be effectively improved by means of EMI phenomena simulation. We will consider the design of a converter intended as battery charger for telecommunication facilities. First of all, the electric phenomena involved in the generation of electromagnetic interference are reminded. Then the main ideas used to obtain the EMI simulation model are outlined. A model of the power converter in the frequency-domain is obtained and validated through experimental measurements. Finally, this model is used to improve the design of the converter from the EMI point of view, resulting in a reduction of space, weight and cost of the filtering devices.

Spread spectrum clock generation techniques (SSCG) were originally developed to reduce EMI in communications and microprocessor systems working in the range of hundreds of MHz. Nowadays, the switching frequency of power converters has been increasing up to values that make feasible the application of such switching frequency modulation techniques to reduce EMI emissions in power converters. Although random modulations have been applied before to power converters, periodic patterns can provide some advantages. The principle of this methods is shown and confirmed with experimental results obtained from tests carried out on a power converter. It is a 600 W boost converter switching at 40 kHz. Attenuations obtained in conducted EMI are evaluated, even under discontinuous conduction mode. Finally, special attention has been paid to converter efficiency, input current distortion and output voltage distortion in order to evaluate possible unwanted side effects produced by this technique

For domestic use, there are numerous switching mode power supplies, composed of a full bridge rectifier with a capacitor filter. It derives a DC voltage from the AC mains and generates a pulsed line current with high harmonic content. This paper deals with a boost unity power factor correction system, which can be added to realise a sinusoidal line current. Two simple and fast DC capacitor voltage controllers are studied and analysed. They are compared in terms of settling time, filtering of twice mains frequency and overshoots of the DC voltage under load transients. The first is based on an integral proportional controller. The second is based on identification of the disturbance and regulation using a pole placement RST controller. The effectiveness of the proposed approach is assessed by simulations and extended to parallel connection PFC systems. A near unity power factor and very low distortion with good output voltage regulation is achieved for variable power applications.

Frequency modulation (FM) techniques have been used to reduce EMI of synchronous digital systems working in the range of hundreds of MHz. The working principle consists of modulating the clock frequency in order to spread the energy of each single harmonic into a certain frequency band, thus reducing the peak amplitude of EMI at the harmonics frequencies. Nowadays the switching frequency of power converters has increased up to values which allow the application of frequency modulation to reduce EMI. The paper summarizes some theoretical principles of FM techniques applied to the switching frequency and shows the effectiveness, in terms of EMI reduction. Experimental tests are presented for validation, evaluating also the possible side effects on the converter efficiency and supply harmonics