Cascaded Power Split Hybrid Drive System with Dual Air Gap Machines
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Solution Overview
Problem
The high costs of electric machines and inverters in hybrid drive systems for hybrid vehicles, particularly due to high electrical power transmission, lead to increased investment barriers and reduced margins, limiting vehicle performance, especially at low speeds and trailer towing capabilities.
Innovation Solution
The implementation of a cascaded power split drive system using mechanically and electromagnetically coupled dual air gap electric machines, which reduces the need for large inverters and simplifies the design, allowing for a mechanical drive path alongside an electrical one, thereby decreasing system complexity, mass, and volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large inverters are used to transmit high electrical power, then power transmission capability is improved, but system cost and complexity increase
Solution Approach 1:
The power transmission system is segmented into multiple paths: a first electrical path with an inverter and a second mechanical path without an inverter. This segmentation allows the electrical power transmission capability to be maintained through the first path while the second mechanical path provides an alternative route that reduces the burden on the inverter, thereby reducing inverter size and system complexity.
2Ease of manufacture
If the transmission ratio range is limited to keep costs down, then system cost is reduced, but vehicle performance at low speed deteriorates
Solution Approach 1:
The system employs a variable transmission ratio mechanism that can dynamically adjust the transmission ratio range. This allows the system to maintain cost-effectiveness with a compact inverter design while adapting the transmission ratio to provide enhanced low-speed performance when needed, thus resolving the contradiction between cost reduction and performance maintenance.
3Power
If the cooling system is designed for high electrical power transmission, then power transmission capability is improved, but system complexity and cost increase
Solution Approach 1:
The power transmission system is divided into electrical and mechanical paths, which segments the cooling requirements. The mechanical path generates less heat and requires simpler cooling, reducing the overall cooling system complexity and cost while maintaining high power transmission capability through the electrical path.
4Weight of moving object
If mechanically integrated electric machines are used, then system mass and volume are reduced, but manufacturing complexity increases
Solution Approach 1:
Multiple electric machines are merged into a single mechanically integrated unit that shares common structural components, magnetic circuits, and control systems. This merging reduces the total mass and volume of the electric machine system while the modular design approach maintains manufacturing feasibility by standardizing the integrated components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces the cost and size of electric machine components, enhances vehicle performance by optimizing power transmission, and improves low-speed drive torque and trailer towing capabilities while maintaining efficient fuel consumption and emission performance.
Implementation Method 1
two mechanically coupled electric machines that form a cascaded power split having both a mechanical and an electrical drive path
Data Source
Figure 1~2
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AI summary
Drive system, in particular for a hybrid vehicle, comprising a power split device (2) with associated drive paths (I,IIa,IIb), wherein at least one of the drive paths comprises two mechanically coupled electric machines that form a cascaded power split having both a mechanical (IIa) and an electrical drive path (IIb). The invention also relates to a hybrid vehicle, a method for transmission of power in a drive system and to the use of a dual air gap electric machine in a drive path of a drive system with a power split device.