Kai Ou

Temperature Control for a Polymer Electrolyte Membrane Fuel Cell by Using Fuzzy Rule

Temperature control for a polymer electrolyte membrane fuel cell (PEMFC) is important in improving power efficiency and increasing fuel cell lifetime. If the temperature of the cell is too low, then the electrochemical reaction response becomes slow, thereby preventing evaporations of liquid water in the membrane. As a result, cell performance is decreased. However, too high temperature leads to waste in catalyst and heat because of excessive chemical reactions and to liquid water evaporation, which decreases proton conductivity. This study develops an electrochemical dynamical model and a thermal model of a PEMFC using MATLAB/Simulink for simulation. Fuzzy control rules are also built to regulate the temperature of a PEMFC. The fuzzy inputs include temperature error, its derivative, and external load current. The cooling fan speed is chosen as an output variable to regulate the temperature of a fuzzy control because the fuel cell utilizes the air cooling method. After confirming that the designed fuzzy rules are effective for controlling cell temperature, a real experimental device is built using an H-100 fuel cell and a cooling fan to verify the effectiveness of the proposed method.

Net Power Output of Open Cathode Fuel Cell Optimization Based on the Over-Temperature Protection

The axial flow fan is the only actuator that simultaneously responses for delivering oxygen and cooling system. In this study, oxygen mass flow rate flowing across cathode channels is regarded as the control variable of the open-cathode fuel cell system. Air flow regulation based on a set of optimal oxygen excess ratios was analyzed in different stack currents. The motor voltage of the axial fan is controlled by the PWM circuit to regulate the air flow speed of the air supply subsystem. The destination of the control strategy centralizes on power optimal and over-temperature protection at the same time while the fuel cell system is running. Based on the fuel cell system model, an integral time absolute error (ITAE) criterion is employed to determine the PI gains of the controller. The verified experiments were implemented on the experiment platform consisted of NI devices.

Sliding-mode-control-based DC/DC converters design and implementation for hybrid proton exchange membrane fuel cell/battery power system

DC/DC converters with hybrid proton exchange membrane (PEM) fuel cell and battery power sources are designed and implemented using sliding mode control (SMC). The converters are typically comprised by unidirectional boost converter and bidirectional converter which are used for regulating the bus voltage and managing power distribution. SMC is selected to control the converters since it can cope with the high non-linear characteristic of the coupled system as well as ensure the stability. The hybrid power control system is constructed in MATLAB/Simulink platform. A comparative approach based on conventional proportional-integral (PI) control is developed to compare the control performance with SMC. The experimental validation is carried out with National Instruments (NI) LabVIEW-based hybrid PEMFC/battery supplied DC/DC converters system prototype.