Improved Voltage Drop Compensation Method for Hybrid Fuel Cell Battery System

Abstract

In this paper, a voltage drop compensation method for hybrid hydrogen fuel cell battery system, with a hydrogen recirculation powering a forklift, is studied. During recirculating hydrogen fuel to recycle hydrogen that has not reacted enough at the system, impurities can be mixed with the hydrogen fuel. This leads to low hydrogen concentration and a drop in the output voltage of the fuel cell system. In excessive voltage drop, the fuel cell system can be shutdown. This paper proposes a voltage drop compensation method using an electrical control algorithm to prevent system shutdown by reducing voltage drop. Technically, voltage drop is typically caused by three kinds of factors: (1) The amount of pure hydrogen supply; (2) the temperature of fuel cell stacks; and (3) the current density to catalysts of the fuel cell. The proposed compensation method detects voltage drop caused by those factors, and generates compensation signals for a controller of a DC–DC converter connecting to the output of the fuel cell stack; thus, the voltage drop is reduced by decreasing output current. At the time, insufficient output current to a load is supplied from the batteries. In this paper, voltage drop caused by the abovementioned three factors is analyzed, and the operating principle of the proposed compensation method is specified. To verify this operation and the feasibility of the proposed method, experiments are conducted by applying it to a 10 kW hybrid fuel cell battery system for a forklift.

Model of Hybrid Electric Vehicle with Two Energy Sources

“…The FC system consists of a PEMFC stack and a fuel controller that controls the operation of this system. The PEMFC control system is connected to a battery controller which regulates the operation and charging of the AGM battery pack [23]. The PEMFC stack is composed of PEMFCs that are connected in series and in parallel to obtain higher output voltages and currents compared to individual cells, whose operating output voltage is approximately 0.6 V. The operation of each PEMFC is important for the operation of the complete system for the purpose of the optimal and efficient use of hydrogen as a propellant.…”

Optimum Load Of a Proton Exchange Membrane Fuel Cells Based on Hydrogen Flow Control

“…Several studies have been carried out to analysis of voltage drops in PEMFC which are caused by operating temperature and the gas pressure [14]. In ref [15] an analysis has been carried out for the voltage drop caused by several parameters consisting of hydrogen flow, temperature and current density of platinum catalyst. In ref [16] an analysis of the gas starvation effects in PEMFC to the dynamic response of current and voltage.…”

Control Methods for Performance Improvement of an Integrated On-Board Battery Charger in Hybrid Electric Vehicles

“…Recently, from the point of view of the entire battery charge system, interest in the issue of the battery management system (BMS) has increased. The purpose of the BMS is to manage the battery and various functions for the BMS, which are classified as real-time monitoring, calculation and prediction, protection, and optimization, which are under development to improve reliability and safety of battery charging [16][17][18][19][20][21].…”