Torque and Power Rating of a Wind-Power PM Generator Drive for Maximum Profit-to-Cost Ratio

This paper compares different solutions in micro wind-power system design. An economic analysis is carried out on the basis of the selected generator, power converter, and mechanical system. An interior permanent-magnet (PM) (IPM) generator is considered since it can be driven in the flux weakening region, exploiting higher turbine rotation speeds, without increasing proportionally the terminal voltage. The performance of the wind-power system adopting the IPM generator is compared with that adopting a surface-mounted PM generator. Several cases are considered, by imposing some constraints on both the maximum input torque of the generator and the volt-ampere rating of the power converter, as well as combining both limitations together. This paper highlights a methodology to determine the economic advantages obtained introducing such limitations, in terms of both return on investment and money profit during a given period, e.g., of 20 years. The study focuses on how to apply the proposed technique, such as constant torque region, flux weakening, and stalling mode, founding the optimal power and torque ratings on the basis of the maximum profit over payback time.