A Novel Twin Epicyclic Gear Train for Optimal Power Sharing Strategy in Two-Motors Driven Hybrid Vehicles

The paper presents a novel approach in power sharing between an internal combustion engine and two electrical motors (M1 and M2) for optimal drive of a hybrid vehicle. It is realized by employing the three Degrees of Freedom (DOF) twin epicyclic gear train with specially selected gear ratios. The first stage of the train provides either a high torque from the IC engine or moderate torque from the motor M1. The second stage provides moderate torque form the motor M2. The motors are capable of providing sufficient speed and torque to drive the vehicle along the horizontal or close to horizontal road surfaces. The closed-loop controller has been designed to provide a proper switching sequence between IC engine and the motors. When vehicle’s torque demand increases beyond of the motors capability (driving up the hill) the controller engages the engine into the system. The designed continuous variable transmission system is able to minimize the power usage of the IC engine and thus to minimize the exhaust gas emission and save cost of petrol usage. Constant charging of the vehicle batteries by the IC engine helps to maintain charge level of the batteries at the nominal level most of the time. 