福衛五號衛星為台灣首次由完全由國人自行設計、分析、組裝、驗證測試的衛星，其主要任務為 2 公尺全 色光 (黑白) / 4 公尺多頻譜 (彩色) 光學遙測酬載，其次搭載先進電離層探測儀，並有多項自主發展關鍵元 件，其中一項為電力次系統的電力控制與分配單元。衛星電力次系統供應衛星本體與酬載儀器任務操作所 需電力，管理衛星電力安全性，並調節太陽電力與衛星電池電力，任務壽命五年，保持衛星可正常執行任 務。本文由硬體元件開始介紹電力次系統，接著描述控制軟體演算法與電能平衡分析，說明福衛五號電力 次系統設計符合衛星系統需求。

FORMOSAT-5 is the fi rst self-developed spacecraft, including design, analysis, assembly, validation and test, by National Space Organization, Taiwan. The mission is (1) a 2-meter panchromatic / 4-meter multispectral Remote Sensing Instrument, (2) Advance Ionosphere Probe. In addition, there are 5 key spacecraft components developed by domestic agencies, one of them is Power Control and Distribution Unit. Electrical Power Subsystem provides electrical power to spacecraft bus and payload instruments with safety control as well as regulates solar array and battery power to ensure appropriate spacecraft operation in fi ve-year mission life. This paper introduces hardware components, control algorithm, and energy balance analysis of the Electrical Power Subsystem on FORMOSAT-5 spacecraft to support its mission.