Modeling and dynamics analysis of electro-mechanical power-trains
Date of Issue2014
School of Mechanical and Aerospace Engineering
In the past few decades, the electro-mechanical power-trains (EMPTs) are being used to replace the conventional power-trains in a few transportations, such as “More Electric Aircraft” and “Hybrid Electric Vehicle”, to improve the energy efficiency and reduce greenhouse emissions. In the EMPTs, the electrical components such as electric machines, power electronics, controllers, and batteries are introduced. To accommodate these new components, the new power-train configurations are also involved. Due to the new components and new configurations, the application of the EMPTs gets a few challenges, including: (1) the nonlinear dynamics in the power-trains have not been sufficiently investigated, resulting in a limitation of the design optimization formulations that can reduce the vibration and noise levels in the power-trains; (2) the electro-mechanical interactions in an EMPT are not fully understood, especially the reflection of the vibration signature onto the stator current of electric machines. Therefore, the stator current has so far not been effectively utilized to analyze the dynamics and monitor the health of the EMPTs; and (3) modeling of the EMPTs is challenging and time consuming due to a large variation in the modeling strategies with respect to an EMPT’s configuration and the intended research application. In other words, there is a lack of a modeling strategy that could be applicable to various types of the EMPTs and be implemented with relative ease. To deal with the before mentioned challenges of the EMPTs, this doctoral research presents a study of the nonlinear dynamics involving gear rattle and electro-mechanical interactions in the power-trains, whose dynamic models were built based on a systematic co-simulation strategy developed for the EMPTs in the study. The key contributions of this doctoral research are as follows, 1. A systematic co-simulation modeling strategy, which utilizes the extensive model libraries of block diagrams (such as MATLAB/SIMULINK), multi-body system (such as SIMPACK), bond graph (such as 20-SIM), and finite element analysis (such as ANSYS and ANSOFT), is proposed to model the EMPTs of various configurations for different research applications. Compared with the existing modeling methods, the proposed co-simulation strategy is applicable to various types of EMPTs and at the same time allows for accurate models to be described with relative ease. 2. The nonlinear dynamics of the power-train having a gearbox during the occurrence of gear rattle was studied by developing a new analytical formulation. The formulation evaluated the level of vibrations and noise emitted during gear rattle by a gearbox with given parameters and therefore can serve as a guideline for gearbox design to reduce the rattle noise concern. This design guideline can help in reducing the time and capital in redesigning and remanufacturing a gearbox, which often result in selection of gearboxes for automotive transmissions due to the excessive vibration and gear rattle. 3. The electro-mechanical interactions were investigated by evaluating the transfer function from the gearbox vibration to the stator current of the electric machines. Using this investigation’s result, a novel condition health monitoring method based on the resonance residual technique is proposed for the EMPTs through the measured stator current. Compared with the existing condition health monitoring methods, this new method is shown to be more sensitive to the incipient faults in the EMPTs.
DRNTU::Engineering::Mechanical engineering::Mechanics and dynamics