Philippe Barrade

Design and Control of a supercapacitor storage system for traction applications

The storage system in this paper is made of supercapacitors. The main goal is to ensure an efficient energy management in a series hybrid vehicle, even if braking resistors are still needed. Design considerations are discussed. In particular the influence of the inductor resistance on the system stability is described. A maximum control structure is then deduced from the energetic macroscopic representation of the storage system. Comparisons between experimentation and simulation are presented in order to highlight the influence of the inductor resistor. Experiments are then carried out on a normal operating cycle.

Direct Connection of Supercapacitors to Photovoltaic Panels With On–Off Maximum Power Point Tracking

A system dedicated to energy storage is presented. It allows energy storage from photovoltaic panels to a compressed air accumulator. This accumulator is controlled to enable compression and expansion modes under Maximum Efficiency Point Tracking (MEPT). A Maximum Power Point Tracking (MPPT) power converter is as usual connected to the solar cells. An intermediary storage tank consisting of supercapacitors and its associated power converter are inserted as a buffer. They adapt the power extracted from the solar cells under the MPPT condition to the power injected into the hydro-pneumatic system under the MEPT condition. Energy transfer from the solar cells to the hydro-pneumatic system is sequentially operated. The number of cascaded power converters decreases the global efficiency of this hybrid accumulator. This paper introduces a solution that consists of the reduction of the number of power converters. It is obtained by a direct connection of the supercapacitors on the solar panels to lower losses. Taking advantage of the sequential energy transfer, the MPPT mode is kept for the solar panels, as well as the MEPT mode for the hydro-pneumatic accumulator. The general topologies, sizing criteria, and control are presented, as well as considerations on efficiency.

Sequential supply for electrical transportation vehicles: properties of the fast energy transfer between supercapacitive tanks

A new feeding concept for electrical transportation systems is presented, based on supercapacitive energy storage. Supercapacitors are new and powerful components for energy storage. Compared with batteries, the amount of energy they can store is low and does not allow a large vehicle autonomy. Because supercapacitors have the property to be re-loadable in a few seconds, a sequential supply system has been developed, considering repetitive feeding at the stops. To solve the problem of the needed high power amount to reach short refill times, a solution is proposed which consists of using an intermediary supercapacitive tank placed at fixed stations, which is refilled between the bus arrivals with a much lower power. In addition to the description of the needed power electronic converters, theoretical and experimental results are presented, defining the controlled profile of the instantaneous power-level, in order to achieve a fast energy transfer between two supercapacitive tanks.

Comparison of Control Strategies for Maximizing Energy in a Supercapacitor Storage Subsystem

Abstract A storage supercapacitor subsystem is studied for insertion in a series hybrid electric vehicle (Fig. 1). This subsystem is composed of a supercapacitor bank and a braking resistor used when the supercapacitor voltage is at its maximum value. Generally, when the maximum voltage is reached by supercapacitor, a voltage drop occurs because of the current cancellation in the series resistance of the supercapacitor. Thus the stored energy is reduced compared to the maximum value that could be reached. To overcome this drawback, new control strategies are proposed by acting on the braking resistor. Energetic Macroscopic Representation (EMR) is used to organize the numerous blocks required for modelling and control. Experiment results are provided and highlight the increase of energy storage.

Optimal Energy Management of an improved elevator with energy storage capacity based on Dynamic Programming

Efficiency and energy consumption reduction are becoming a key issue in elevation applications. Energy Storage Systems (ESS) can play a significant role on this field, together with their associated Energy Management System (EMS) in order to optimize the overall behavior of the elevator. This paper presents an EMS based on Dynamic Programming (DP) for a stochastic application, introducing a novel representation of these systems (General Energy and Statistical Description) and implementing a cost function based on the stock management theory. It has been implemented and validated experimentally on a real elevator with energy storage capability reducing grid power peaks by 65% and braking resistor energy losses up to 84%.

Original articles: Influence of the mechanical limitations of a traction system on energy storage design

An innovative subway without supply rail is presented. This article deals with the sizing of the required on-board energy between two stations in the worst case. The influence of the mechanical limitations is studied: acceleration, jerk and torque limitations. These limitations have an impact on the total energy required and thus on the size of the on-bard energy storage element. These mechanical limitations must thus to be taken into account in the energy storage design.

Energetic Macroscopic representation and PSIM ® simulation: Application to a DC/DC converter input filter stability

Simulation is a key issue in the design of control electrical systems. Simulation packages using component library, such as PSIM®, are very useful to achieve this goal. The simulation model is thus easily built from the system topology (structural model). But the deduction of the control scheme is more difficult, because a functional model is more suitable. Some graphical descriptions, such as EMR (Energetic Macroscopic representation) are recently been developed to help the user in the control scheme design. But they are generally associated with functional software, such as Matlab-Simulink®. In this paper, a structural modeling software is combined with a functional modeling method. An original and new control of a DC/DC converter is taken as an example.

An energetic based method leading to merged control loops for the stability of input filters

In most of applications, power converters are controlled to allow their output current/voltage to follow the required reference values. For DC/DC and DC/AC converters, the control must take into account their input voltage, which must be rejected. In such conditions, the converters can be modeled as negative impedance, causing the instability of their feeding 2nd order input filter. This paper presents an original method for the stabilization of the input filter. A merged control scheme is defined using an Energetic based method. A first control scheme is defined to control the output current. A second independent control scheme is defined to control the filter stability. Both control loops are merged using a weighing criterion. Simulation results are provided and the stability issue is discussed.

Energetic Macroscopic Representation of a hybrid storage system based on supercapacitors and compressed air

A hybrid energy storage system has been proposed using supercapacitor and compressed air [1] in order to store energy from photovoltaic panels. A simulation model is developed using energetic macroscopic representation. Such a description can be used to deduce new control laws of the hybrid storage system using specific inversion rules. The simulation model is validated by comparison with experimental results.

Design methodology of an electric vehicle hybrid energy storage unit for improved energy efficiency

This work proposes a design methodology that allows designing the energy storage unit of an electric vehicle in order to minimize the required energy and the resulting losses. A simple analytical model of the vehicle losses is derived. Driving conditions and solar production scenarios are obtained from stochastic processes; they are employed to generate a number of vehicle power profiles. Candidate supercapacitor arrangements are classified in terms of losses and energy capacity, leading to the associated Pareto minimum.