Optimal design of three-planetary-gear power-split hybrid powertrains

TL;DR

This paper presents a systematic optimization methodology for designing multi-mode three-planetary-gear hybrid powertrains, improving fuel economy and performance for light trucks by exploring clutch topologies and energy management strategies.

Contribution

It introduces an exhaustive search and optimization framework for multi-mode HEV designs with three PGs, identifying efficient configurations with fewer clutches and better performance.

Findings

Identified 8 optimal designs with improved launching performance.

Achieved better fuel economy compared to benchmark designs.

Reduced number of clutches needed for effective operation.

Abstract

Many of today's power-split hybrid electric vehicles (HEVs) utilize planetary gears (PGs) to connect the powertrain elements together. Recent power-split HEVs tend to use two PGs and some of them have multiple modes to achieve better fuel economy and driving performance. Looking to the future, hybrid powertrain technologies must be enhanced to design hybrid light trucks. For light trucks, the need for multi-mode and more PGs is stronger, to achieve the required performance. To systematically explore all the possible designs of multi-mode HEVs with three PGs, an efficient searching and optimization methodology is proposed. All possible clutch topology and modes for one existing configuration that uses three PGs were exhaustively searched. The launching performance is first used to screen out designs that fail to satisfy the required launching performance. A near-optimal and computationally efficient energy management strategy was then employed to identify designs that achieve good fuel economy. The proposed design process successfully identify 8 designs that achieve better launching performance and better fuel economy, while using fewer number of clutches than the benchmark and a patented design.