Powertrain Load Distribution via Efficiency Maps
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Solution Overview
Problem
Existing methods for determining load distribution in hybrid and electric vehicles with multiple traction motors do not consider total efficiency, leading to suboptimal performance in terms of driving performance and fuel or energy consumption.
Innovation Solution
A method and control unit that determine a load distribution characteristic map based on efficiency characteristic maps of each drive machine, optimizing the distribution to achieve maximum total efficiency by accounting for power losses and operational parameters such as rotational speed and torque, allowing for dynamic adjustment of load distribution between front-wheel and rear-wheel drives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed load distribution value is used (e.g., sport mode or eco mode), then the control system is simple to operate, but the total efficiency of the powertrain is not optimized
Solution Approach 1:
The patent implements dynamic load distribution by continuously adjusting the power allocation between front and rear drive machines based on real-time operating conditions. The control unit calculates optimal distribution ratios using efficiency characteristic maps that account for rotational speed, torque, and power loss parameters, enabling the system to adapt to varying driving conditions rather than relying on fixed mode-based distributions.
Solution Approach 2:
The system changes key operating parameters (rotational speed, torque, power loss) as inputs to the load distribution calculation. By monitoring these parameters and using them to query efficiency characteristic maps, the control unit dynamically adjusts the load distribution ratio to maintain optimal total efficiency across different operating points.
2Power
If mode-based load distribution is used (sport mode, eco mode), then the driving performance is optimized for specific conditions, but the efficiency is not optimized across all operating points
Solution Approach 1:
The patent uses parameter changes by continuously monitoring rotational speed, torque, and power loss as input variables. These parameters are used to dynamically query efficiency characteristic maps and calculate optimal load distribution ratios, replacing the discrete mode-based approach with a continuous parameter-driven control strategy that optimizes both performance and energy efficiency across all operating conditions.
Solution Approach 2:
The system implements feedback control by continuously measuring actual operating parameters (rotational speed, torque, power loss) and using this information to adjust the load distribution in real-time. The control unit compares current operating conditions against stored efficiency characteristic maps and modifies the power distribution between front and rear drive machines to maintain optimal efficiency, creating a closed-loop control system.
3Reliability
If slip-based four-wheel drive switching is used, then the traction is improved when needed, but the load distribution remains simple and not efficiency-optimized
Solution Approach 1:
The patent extends beyond simple slip-based switching by using multiple parameters (rotational speed, torque, power loss) to determine load distribution. This multi-parameter approach allows the system to optimize energy efficiency while maintaining necessary four-wheel drive operation, rather than relying solely on binary slip-based activation.
Solution Approach 2:
The system transitions from static, condition-based four-wheel drive switching to dynamic load distribution that continuously adjusts power allocation based on real-time efficiency calculations. This dynamic approach optimizes energy consumption by distributing load according to the actual efficiency characteristics of each drive machine rather than simply switching between fixed configurations.
Data Source
AI summary
A method for determining a load distribution in a powertrain of a motor vehicle, whereby the powertrain has at least two drive machines, whereby the first drive machine is provided for a front-wheel drive and the second drive machine is provided for a rear-wheel drive, whereby the method comprises: determining a load distribution characteristic map that is based on a first efficiency characteristic map of the first drive machine and on a second efficiency characteristic map of the second drive machine.