EMIVT Control Using Engine Torque Mode and Machine Speed Switching
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Solution Overview
Problem
Existing control strategies for multi-mode electro-mechanical infinitely variable transmissions (EMIVT) in vehicles constrain driveline performance and efficiency, requiring significant tuning for each vehicle configuration and reducing efficiency due to mode switching strategies that operate the engine in speed control modes.
Innovation Solution
Operating the engine in a torque control mode and switching control modes of first and second electric machines based on their speeds, independent of clutch states and vehicle speed, to simplify control and extend the operating envelope of the EMIVT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the engine is operated in speed control mode with mode switching based on vehicle speed, then the DC voltage bus stability is maintained, but the driveline performance and efficiency are reduced
Solution Approach 1:
The patent changes the control parameter from speed control to torque control for the engine. By operating the engine in torque control mode rather than speed control mode, the system maintains DC voltage bus stability while avoiding the efficiency losses associated with traditional mode switching strategies. This parameter change allows the engine to operate in optimal torque ranges without being constrained by speed-based mode transitions.
2Stability of the object's composition
If mode switching strategy is implemented based on vehicle speed, then the DC voltage bus stability is achieved, but significant tuning is required for each vehicle configuration
Solution Approach 1:
The patent implements a universal control strategy where the engine operates in torque control mode across all operating conditions, eliminating the need for vehicle-speed-based mode switching. This approach makes the control system universally applicable to different vehicle configurations without requiring significant retuning, as torque control is inherently more adaptable to varying vehicle setups than speed control.
3Stability of the object's composition
If the engine is operated in speed control mode, then the DC voltage bus stability is maintained, but vehicle drivability is reduced
Solution Approach 1:
The patent inverts the traditional control approach by operating the engine in torque control mode instead of speed control mode. This inversion allows the electric machines to handle speed regulation while the engine focuses on torque production, resulting in improved vehicle drivability and responsiveness while maintaining DC voltage bus stability through alternative control mechanisms.
Data Source
AI summary
A method and system for operating a multi-mode electro-mechanical infinitely variable transmission (EMIVT) that is coupled to an engine and includes two electric machines is described. In one example, operating modes of the two electric machines are controlled without regard to vehicle speed and system conditions that are external to the two electric machines.