@techreport{oai:jaxa.repo.nii.ac.jp:00045190,
 author = {外立, 政隆 and 半沢, 麻雄 and 室田, 勝一 and 野口, 正芳 and HASHIDATE, Masataka and HANZAWA, Asao and MUROTA, Katsuichi and NOGUCHI, Masayoshi},
 month = {May},
 note = {The rotor speed control of windmills plays an essential roll in their practical use. Rotor speed control technology is indispensable not only in attainning a high level of energy conversion efficiency but also in avoiding damage to the windmill rotor system under very strong wind conditions. The present study was conducted as a part of the component technology research and development program for the 20kw horizontal axis windmill system development project sponsored by the Science and Technology Agency of the Japanese government. A hydraulic pitch control system for a 1kw class windmill (a pioneering sub-scale model for the 20kw windmill) was developed and improved through repeated tests in the NAL low speed wind tunnel and through outdoor tests. Our original application of the electromagnetic proportional hydro-relief valve to the hydraulic pitch control system of windmills brought an outstanding reduction of the variation in windmill rotational speed. The test results confirm the excellent characteristics of the windmill rotor speed control. The practicality of the hydraulic pitch control system has been proving itself in the 20kw windmill operation since December 1985., 資料番号: NALTR0931000, レポート番号: NAL TR-931},
 title = {Study on a Rotor Speed Control System for a Horizontal Axis Windmill},
 year = {1987}
}