The rectifiers influence on the size of direct-driven generators

Paper in proceeding, 1999

Direct-driven wind turbine generators have a high inductance compared with normal 1500-rpm generators. Therefore, their rated power and efficiency are sensitive to the type of rectifier they are connected to. The mechanisms behind this are discussed and four different rectifiers are presented and compared. Through simulations it has been shown that a transistor rectifier utilizes the generator well and can lead to low generator currents and a constant flux linkage. An almost constant flux linkage is achievable also with a series compensated diode rectifier, while part-load currents are slightly higher than for the transistor rectifier. A plain diode rectifier cannot utilize the generator well and a shunt compensated rectifier leads to high flux linkage at part-load.