Serge Loudot

Unlimited range for electric vehicles

The dynamic inductive power transfer for Electric Vehicles is a solution to fill the main drawback of electric vehicles, namely autonomy. Compatible with the static inductive charging, this solution also provides high added value because there are no more cable handling, the charge is done transparently to the user. This value can be a constraint if it is necessary to position the EV very precisely in order to recharge. The wireless charger must be sufficiently tolerant to misalignment. Although already developed in other articles, the selected topology, combined with clever design based on Fresnel diagrams and simple control but with a significant dynamic, allows a large misalignment without loss of power or efficiency. The control method makes the charger compatible with the on-road charging. A demonstrator of 2kW under 60V, currently achieved, can demonstrate the performance of this topology, especially during movements of the secondary side relative to the primary side. We propose, in this paper, to control the output voltage and enable operation at low power to make the entire system a complete and efficient charger, while being able to operate dynamically. This control is done without any communication between the primary side and the secondary side of the transformer.

2.4 kW prototype of on-road Wireless Power Transfer: Modelling concepts and practical implementation

This article focuses on Wireless Power Transfer, adapted to a dynamic charging infrastructure. The authors present a high-efficiency 2.4 kW prototype of electric road, designed according to an analysis based on phasor diagrams to size the key-elements of the SS resonant converter. It involves 50-cm square coils, with an air-gap of 15 cm between the ground and the on-board sides, for an automotive application. The system uses a ZPA method control on both ground and on-board parts of the air-transformer, implemented with a varying-frequency inverter. The experimental results show a very steady and stable on-board voltage despite the evolutive magnetic coupling with the displacement of the load, from -18 cm to 18 cm. The efficiency measures presented in this article reach 91% and never falls below 70%. These data being measured with an emitted voltage of 30 V (half the operating voltage), the operating efficiency reaches even higher values. The efficiency is also very stable with displacement. Furthermore, the system has a very good dynamic response: the switch between one coil to the next during the motion of the load does not exceed 4 ms, and the adaptive response to a 280 W output power step lasts only 1.1 ms before the permanent regime.

Analysis of DC-link current harmonics for unconventional PWM strategies — Application of the double Fourier integral Method

This paper presents a numerical approach for determining the theoretical harmonic components of unconventional pulse width modulation (PWM) strategies such as the Unified-Double Carrier PWM (Uni-DC PWM). The method uses a double Fourier integral formulation to analyze the inverter DC-link current harmonic components, by establishing inner and outer integral limits of this formulation. The provided results of the investigated modulation strategy are demonstrated by comparing with those obtained by Fast Fourier Transform (FFT) analysis of simulated switched waveforms for selected conditions. 3D graphics and general cartographies for global variation of the DC bus RMS current are also presented, together with a comparison of the harmonic performance of a classic PWM strategy and the Uni-DC PWM.

Impact of a non-conventional PWM strategy on the DC link film capacitor sizing

In this paper, an analysis of the DC-link voltage ripple for classic and non-conventional Pulse Width Modulation (PWM) strategies such as the Unified-Double Carrier PWM (Uni-DC PWM) is derived. A focus will be held on the case where Film capacitors are applied. The latter have a very low Equivalent Series Resistance (ESR) which is responsible of losses in real capacitors (especially Electrolytic ones) hence, in the frequency range where the PWM harmonics do exist, a Film capacitor can be considered as having a pure capacitive impedance where the DC-link voltage ripple becomes highly dependent on the harmonic frequency distribution. Thus, it is important to determine the exact harmonic components needed for an analysis to be effective and this is where the double Fourier integral provides a mathematically rigorous application for studying PWM characteristics in the frequency domain. Despite the fact that the main objective of the Uni-DC PWM is to reduce the capacitors RMS current, results show a reverse impact on the DC-link voltage ripple when a Film capacitor is used.

Test bench for active ageing of power modules reproducing constraints close to automotive driving conditions

Power modules designed for hybrid/electric traction should fulfil lean manufacturing considerations. Robustness study of IGBT modules on the basis of a representative driving cycle is mandatory for safety reasons, cost and lifetime estimation. So power modules can not be oversized and harsh stresses applied conduct to review ageing tests. The power modules for motor drives are subject to multiple failure modes which are due to many damaging factors. Generally we perform the damage evaluation of power modules by thermal and active accelerated power cycling tests. In order to take into account of new automotive domain requirements, this paper proposes a tester applying low voltage electrothermal stresses on power module close to the automotive urban driving conditions.