Differential Flatness Control Research Articles

Control of PEMFC system air group using differential flatness approach: Validation by a dynamic fuel cell system model

In this paper, a non linear control strategy is applied to the air supply subsystem of a polymer electrode membrane fuel cell (PEMFC). Based on a simplified control model and using the differential flatness control theory, a controller is designed in order to regulate the most important variables in the air supply subsystem: the oxygen stoechiometry and the cathode pressure. Simulations are made using a very detailed model validated experimentally, which allows the evolution of different state variables in the stack to be observed during the power deliver operation. The simulation results show that the controller gives a good response in terms of performance, robustness and durability of the system, despite the dynamics power profiles demanded, the approximations made and the disturbances.

Flatness-Based Control of Three-Phase Inverter With Output $LC$ Filter

Recently, hybrid electrical power sources composed of storage elements and renewable energy sources are known to have made great development. These energy sources are connected to a dc bus and need a dc-to-ac converter to transfer the produced energy to the grid. Three-leg voltage source inverters equipped with an output LC filter are often used. The main objective of this stage is to generate a three-phase sinusoidal voltage with defined amplitude and to ensure the smallest harmonic distortion rate of the output voltage for any load conditions. To satisfy the defined objectives, we present in this paper a new control method based on differential flatness control technique. The main interest of this control method is the possibility to define the behavior of the state variable system in the steady state as well as in transients. The use of only one control loop allows obtaining high dynamic properties of the system which ensure small harmonic distortion rate of the output voltage. Experimental results under balanced, unbalanced, and nonlinear load conditions are presented and validate the effectiveness of the proposed control methods.

Modeling and Control of Fuel Cell/Supercapacitor Hybrid Source Based on Differential Flatness Control

Fuel-cell vehicles (FCVs) with energy storage (ES) device(s) could result in improved lifetime, performance, fuel economy, and reduced cost. This paper presents the utilization of an ES device consisting of a supercapacitor bank for future electric vehicles with a hydrogen fuel cell (FC) as the main power source. The study mainly focuses on the innovative control law based on the flatness properties for a FC/supercapacitor hybrid power source. Utilizing the flatness principle, we propose simple solutions to the hybrid energy-management and stabilization problems. A supercapacitor module, as a high dynamic and high-power density device, functions to supply energy to regulate the dc-bus energy. The FC, as a slower dynamic source in this system, functions by supplying energy to keep the supercapacitor module charged. To ensure energy-efficient operation of the FC stack, the output current ripple of the FC stack is minimized by parallel boost converters with an interleaving switching technique for a high-frequency ripple by the supercapacitor for a low-frequency ripple. To authenticate the proposed control laws, a test bench is realized in the laboratory. The control algorithm (energy and current control loops) is digitally implemented by dSPACE controller DS1103. Experimental results with small-scale devices (a proton exchange membrane FC (PEMFC) of 500 W, 50 A, and 10 V and a supercapacitor bank of 250 F, 32 V, and 500 A) substantiate the excellent performance during load cycles.

Regulation and tracking for the average boost converter circuit: A generalized proportional integral approach

In this article we examine, in the context of constant equilibrium stabilization and equilibrium-to-equilibrium reference trajectory tracking, the generalized proportional integral (GPI) control of a non-linear average model of a DC-to-DC power converter of the 'Boost' type. We particularly emphasize the links between differential flatness and GPI control in the state feedback controllers design and synthesis tasks, respectively. The design approach relies on the converter's tangent linearization models for each case. The performance of the feedback controlled non-linear system is evaluated by means of digital computer simulations including large, unmodelled, load parameter variations.