Hybrid Vehicle Driving Force Control for Engine Start-Stop Reduction
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Solution Overview
Problem
Hybrid vehicles experience frequent starting and stopping of the internal combustion engine, leading to driver discomfort and increased shock due to inefficient battery charging and discharging strategies, which do not effectively reduce the switching frequency between engine operation modes.
Innovation Solution
A driving force control device for hybrid vehicles that calculates travel loads and identifies regeneration possible intervals, estimating the energy that can be regenerated and distributing it to adjacent intervals to minimize internal combustion engine output, thereby reducing engine start-stop events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the remaining battery capacity is consumed entirely by the summit of the uphill road to enable regeneration in downhill interval, then the internal combustion engine can be stopped during uphill travel, but the switching frequency between stopping and starting of the internal combustion engine increases, causing shock and driver discomfort
Solution Approach 1:
The control device performs preliminary calculation of the travel load for the entire predicted route before making control decisions. By dividing the route into multiple intervals and calculating the travel load for each interval in advance, the system can plan the battery discharge strategy ahead of time to ensure the engine runs continuously without frequent stop-start operations, thereby reducing driver discomfort while maintaining fuel efficiency benefits
2Use of energy by moving object
If the internal combustion engine is stopped frequently to increase electric motor travel opportunities, then fuel consumption is reduced, but the actual switching frequency between stopping and starting of the internal combustion engine cannot be reduced
Solution Approach 1:
The control device continuously monitors the actual vehicle position, remaining battery capacity, and predicted route conditions, then adjusts the discharge amount for each interval based on this feedback. This closed-loop control ensures that the engine operates stably by making informed decisions about when to discharge the battery and when to maintain engine operation, balancing fuel consumption reduction with operational stability
3Loss of energy
If the battery is discharged earlier to enable engine stopping on uphill roads, then regeneration opportunities are created, but the discharge strategy does not optimize the overall travel load distribution
Solution Approach 1:
The control device divides the predicted route into multiple intervals and calculates the travel load for each interval separately. This segmentation allows the system to identify specific intervals where the engine can be stopped and to distribute the total discharge amount appropriately across different intervals, optimizing regeneration efficiency while maintaining manageable control complexity through structured breakdown of the control problem
Data Source
AI summary
A driving force control device for a hybrid vehicle includes: a travel load calculation unit adapted to divide a predicted route from a current position to a predetermined distance ahead into a plurality of intervals, and to estimate a travel load in each interval; a recommended discharge amount calculation unit adapted to search for a regeneration possible interval, in which a travel condition required by a driver can be maintained even when an output of an internal combustion engine is stopped and regeneration is performed by a motor/generator, from an estimation result, and to estimate a charge amount expected value in the regeneration possible interval, and distributes the charge amount expected value preferentially to an adjacent interval to the regeneration possible interval as a recommended discharge amount in order to stop the output of the internal combustion engine; and an energy management unit that controls an operation of the motor/generator in the current position on the basis of a travel condition, a state of charge, and the recommended discharge amount in the current position.