A prototype for airflow speed control in a subsonic wind tunnel

The article presents the framework of an update program for the wind tunnel from the University of Craiova, Romania. The program consists of many stages: system prototyping with LabVIEW control, control algorithm implementation with a microcontroller, high-power rectifier development, and all system testing. In this article, a first prototype for the d.c. motor control system was detailed, which mainly consists of a three-phase rectifier and a PI control algorithm implemented in LabVIEW. The control loop is closed, using a rotation motor speed transducer. The motor speed, current waveform through the motor, and the voltages from each phase are acquired using a NI-USB 6251 data acquisition card. The command voltage for the three-phase rectifier is also obtained from one of the data acquisition card analog output. The power source used in this prototype was a three-phase rotating converter. The electronic scheme of the rectifier was designed using Multisim.