Electric Drive System for Hybrid Power Vehicles Based on the Doubly-Fed Induction Generator Direct-Drive Induction Motor Structure: Integration and Control Algorithm

This paper proposes a hybrid electric vehicle (HEV) transmission system using a doubly-fed induction generator (DFIG) that directly drives an induction motor (IM). The purpose is to reduce the capacity and voltage level of the inverter in the system, thereby reducing costs. The DFIG's rotor is managed by a small inverter, and the IM is directly driven by the DFIG's stator. A speed matching algorithm is developed to optimize the internal combustion engine's (ICE) efficiency and minimize the inverter's power and voltage by adjusting the vehicle's speed in some intervals, that keeps the ICE either idling or in a high-efficiency state. Additionally, the paper introduces a vector control algorithm for the DFIG direct-drive IM integrated system, ensuring high-performance speed control similar to the traditional vector control for single motor. Experiment results prove that this system meets the vehicle's speed control requirements and reduces the inverter's power and voltage to less than 2/3 of the original system.