<p>This paper aims to design and experimentally validate a large direct-drive permanent magnet generator for low speed and high torque applications such as tidal and wind power generation systems. Direct-drive generator systems are often favored over geared systems due to their superior reliability and availability. Consequently, the focus of this paper is on the direct-drive generator concept. The electromagnetic configuration is based on a radial flux surface-mounted permanent magnet machine, utilizing segmented iron cores and windings in the stator. Large direct-drive generators typically operate at low speeds with high torque ratings, which limits the effectiveness of conventional motor-generator test beds for testing such high-torque systems. To address this limitation, the paper discusses a performance verification method using an internal back-to-back test, thereby eliminating the need for a large motorgenerator test bed. The paper begins with a rough design of the generator’s electromagnetic parts, followed by a detailed electromagnetic and mechanical design using finite element analysis. Next, the internal back-to-back test is presented as a means of design validation and performance assessment of a direct-drive generator for low speed and high torque applications. The generator output closely matched the results of the analysis and the test.</p>