Based on the requirement of Direct Methanol Fuel Cell testing

the subsystem of gas flux control was established with the subassemblies composed of multiplied function data collection board

industry control computer

proportional flux solenoid valve，and digital display flowmeter. The control programme was made with LabVIEW

including the improved autotuning PID algorithm. The accuracy of gas flux control for Micro/Miniature Fuel Cells Testing System was improved

and data record and display were realized during the experimental process. The structure and design method of gas flux servo control system were investigated. The driver of proportional flux solenoid valve was designed and fabricated according to the principle of the voltage controlled constant-current source. Based on the character of the driver

the autotuning PID algorithm was improved and realized under the environment of LabVIEW. With the adjustable PID parameters

the steady state accuracy of gas flux control was improved

which is up to ±0.1L/min. The rise time of step response for 0-5L/min

0-10L/min

0-20L/min

and 0-50L/min is 0.9S

4.9S

5.2S

and 6.6S

respectively

and the overshoot is less than 0.23L/min

which is acceptable.