Control Techniques With System Efficiency Comparison for Microwind Turbines

This paper presents the implementation of a sensorless speed controller and active rectification in a microwind turbine intended for battery charging. The controller was tested in a wind turbine emulator test rig using real wind data available from British bases in Antarctica. The control algorithm was successfully tested up to 14 m/s wind speed. Beyond this point, the electrical unbalance in the turbine generator compromised the stability and performance of the system. Also, a system efficiency comparison of different control algorithms is given to demonstrate the advantages of using active rectification instead of passive diode rectifiers in microwind turbines. This comparison was done between the sensorless control plus active rectifier, a dc-dc converter regulator, and the direct connection between the turbine and battery by means of a diode rectifier. The turbine with an active rectifier and sensorless control achieved the highest power coefficient over the range of wind speeds showing that this technique is an attractive and relatively low-cost solution for maintaining good performance of microwind turbines at low and moderate wind speeds.