Design Study on Hybrid Excitation Generator for Micro-hydroelectric System

This paper presents design study on a hybrid excitation machine as a generator for a micro-hydroelectric system. A hybrid excitation generator is a kind of variable flux machines and has two mmf sources such as a perma-nent magnet and the field excitation coil that enables to ad-just a total amount of airgap field flux produced by two mmf sources. With the variable field flux capability, a hy-brid excitation generator promises to expand high torque operating range at low speed region while keeping operating power range at middle and high-speed region as required in the target application under given maximum voltage and current restrictions. Application-oriented design of hybrid excitation generator under given design constraints and specifications using finite element electromagnetic analysis is conducted. As a result, it is confirmed that the designed hybrid excitation generator meets the requirement for a target micro-hydroelectric system.