Electro-mechanical Transmission Torque Constraint Management
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Solution Overview
Problem
Existing hybrid powertrain systems face challenges in efficiently managing torque and battery power constraints across multiple torque-generative devices, leading to suboptimal performance and efficiency in achieving required motor torques and battery power levels.
Innovation Solution
A method for controlling an electro-mechanical transmission that determines minimum and maximum motor torque constraints and battery power constraints to select a predetermined operating zone, allowing for the calculation of optimal output torque based on these constraints, ensuring efficient power transmission and management between an internal combustion engine, electric machines, and the battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple torque-generative devices are used to increase system power capability, then the power output is improved, but the complexity of managing torque and battery power constraints increases
Solution Approach 1:
The patent segments the power management problem into three distinct operating zones (first zone with sufficient battery power, second zone with limited discharging power, third zone with charging capability) based on battery state of charge and power constraints. This segmentation allows the control system to apply different torque allocation strategies for each zone, simplifying the overall management complexity while maintaining multiple torque-generative devices for high power output capability.
2Reliability
If battery power constraints are strictly enforced to protect the energy storage device, then the reliability is improved, but the ability to achieve required motor torques is limited
Solution Approach 1:
The patent implements dynamic torque constraint determination where the maximum motor torque constraints for the first and second electric machines are adjusted in real-time based on the determined operating zone and battery power constraints. In the first zone, higher torque constraints are allowed; in the second zone, reduced constraints protect the battery; in the third zone, torque constraints are set to enable battery charging. This dynamic adjustment ensures both battery reliability and adequate motor torque achievement under varying conditions.
3Adaptability or versatility
If the system operates in multiple zones based on battery power constraints, then the adaptability is improved, but the control complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-defining three distinct operating zones with specific torque constraint characteristics before real-time operation. The control system evaluates the current battery state and determines which pre-defined zone applies, then retrieves the corresponding torque constraints. This approach provides high adaptability to different operating conditions while avoiding the complexity of real-time optimization algorithms, as the zone boundaries and constraint relationships are established in advance.
Data Source
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AI summary
A powertrain including an electro-mechanical transmission (10) mechanically-operatively coupled to an internal combustion engine (14) and first (56) and second (72) electric machines to transmit power to an output member (64) is disclosed. A method for controlling the electro-mechanical transmission (10) includes determining minimum and maximum motor torque constraints for the first (56) and second (74) electric machines, and determining available battery power in terms of battery power constraints. One of a first, a second and a third case is determined based upon the motor torque constraints and the battery power constraints. A preferred output torque is determined for transmitting to the output member (64) of the electro-mechanical transmission (10).