Electrical – Why speed of the wind turbine permanant magnet synchronous generator speed reduces when connected to the load


I have 100 W vertical axis wind turbine which is mounted on PMSG. And its generated 3 phase voltage is converted to dc using H bridg rectifier. When I connect the load, the turbine speed will reduce. Why it happen

Best Answer

It's a very basic behavior of any generator. Load creates torque reverse to one that is driven by the power source. Imagine a small generator, like your own, connected to an electrical locomotive. No chance it will move!

Another way to look is by power. Power it limited at some point. Mechanically it is rotation speed times torque, electrically it's voltage (speed times a factor) times current. When no load applied, mechanical power is completely wasted on mechanical losses. If load is applied, electrical power is no longer zero, so mechanical lisses must be reduced, and it means less speed.