Output Voltage Regulation of a Fuel Cell/Boost Converter System: A PI-PBC Approach

TL;DR

This paper presents a passivity-based PI control method for regulating the output voltage of a fuel cell connected to a boost converter, ensuring robust performance despite load uncertainties and nonlinearities.

Contribution

It introduces a simple PI-PBC approach with guaranteed convergence for all positive gains and an estimator for unknown loads, enhancing voltage regulation robustness.

Findings

Voltage converges to desired level for all initial conditions

PI gains can be tuned easily due to guaranteed convergence

System maintains stability and robustness under load variations

Abstract

In this paper we consider the problem of voltage regulation of a proton exchange membrane fuel cell connected to an uncertain load through a boost converter. We show that, in spite of the inherent nonlinearities in the current-voltage behaviour of the fuel cell, the voltage of a fuel cell/boost converter system can be regulated with a simple proportional-integral (PI) action designed following the {Passivity-based Control (PBC) approach. The system under consideration consists of a DC-DC converter interfacing a fuel cell with a resistive load. We show that the output voltage of the converter converges to its desired constant value for all the systems initial conditions -- with convergence ensured for all positive values of the PI gains. This latter feature facilitates the, usually difficult, task of tuning the gains of the PI. An Immersion and Invariance parameter estimator is afterwards proposed which allows the operation of the PI-PBC when the load is unknown, maintaining the output voltage at the desired level. The stable operation of the overall system is proved and the approach is validated with extensive numerical simulations considering real-life scenarios, where a robust behavior in spite of load variations is obtained.