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International audience; Power loads are often modeled as constant power loads (CPLs) for stability analysis. However, this model may be too strict, and practical power loads are not ideal CPLs. In this paper, a discrete-time modeling is applied to the model of a power load of a dc system that is composed of a source converter, an LC filter, and the power load. A stabilizer is then added to the command scheme of the source converter in order to increase the maximum stable power of the system. The model also takes into account the dynamics of the load. Simulation and experimental results are given to validate the proposed model and to demonstrate the effectiveness of the proposed stabilizer, tuning of the stabilizer parameter, and the load current controller gain.

International audience; Power electronics-based AC/DC microgrids are attractive for clean energy applications, and are the enabling technology for hybrid energy systems in the more electric transportation. In such hybrid energy systems, storage units like battery and supercapacitor (SC) are used to store the surplus energy and to regulate the DC bus voltage. In on-board electric power systems, the converter controlled loads act as constant power loads (CPLs), imposing fast dynamics to the system. In this paper, a simple power control approach is proposed to provide the energy management and to ensure the stable operation of the system in the presence of CPLs. Furthermore, a laboratory prototype is built in order to validate the performance of the controller and the energy management strategy. The control system is implemented on dSPACE real-time cards. The simulated control scenarios are then experimented with the hardware prototype.

International audience; Tightly controlled power converters are often modeled as constant power load. In transportation system, the input filters are small and not much damped to save weight/volume. In order to know when the system becomes unstable with those small LC filters and high cut-off frequency, the conventional analysis based on an average model may not be accurate enough. In this paper, a new discrete-time model is proposed to investigate the behavior of the studied system and to take into account the switching effect. A stabilizer is also proposed to increase the maximum power. This system is composed of a dc-dc boost converter with a modified control, an LC filter, and a constant power load. Experimental results confirm the validity of the proposed tool.

International audience; For stability analysis, it is often chosen to model power loads by constant power loads (CPL). However, this model may be too strict, as it is the worst case scenario. In this paper, it is intended to change the model of a power load to increase the calculated stability zone of a DC system composed of a source converter, an LC filter and the power load. A stabilization term is included in the command of the source in order to increase the power range. The simulation and experimental results that are given to validate the proposed model and to demonstrate the effectiveness of the proposed stabilizer and its tuning.