DC-link voltage selection for a multi-MW wind turbine
Journal article, 2014
Purpose – The purpose of this paper is to investigate how the dc-link voltage for the converter of
a wind generator should be selected, i.e. to determine the losses in the generator and the converter
when using various dc-link voltage levels.
Design/methodology/approach – To presents the efficiency evaluation of 5MW wind turbine
generating systems, two 5MW surface mounted permanent magnet synchronous generators (PMSG)
with medium and low rated voltage is designed. A two-level transistor converter is considered for ac/dc
conversion. Three different dc-link voltage levels are used. By using these voltage levels the PMSG is
utilized in slightly different ways.
Findings – It is found that the system with the lower voltage machine has slightly higher annual
energy efficiency compare to the higher voltage system. Furthermore, it is shown that the best choice
for the dc-link voltage level is a voltage between the minimum voltage which gives the desired torque
and the voltage which gives Maximum Torque Per Ampere.
Originality/value – A procedure as well as investigations with quantified results on how to find the
highest complete drive system efficiency for a wind turbine application. Based on two given PMSG,
the most energy-efficient dc-link voltage has been established.
Permanent magnet machine
Conduction and Switching losses
Annual energy efficiency