Hybrid Vehicle Charge Control to Limit Shock From Torque Estimation Error
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Solution Overview
Problem
The challenge in controlling the charge of an electric power accumulator in a vehicle with an engine and electric motor system is the poor estimation accuracy of engine torque, leading to increased differences between actual and estimated values, which can cause shocks during charge control.
Innovation Solution
A control device with a power source control unit to increase engine torque for charge demand and a charge limit control unit to limit charging power based on fixed rotation and torque thresholds, vehicle velocity, and gear ratio, thereby suppressing shock occurrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine torque is increased to achieve the demanded charging power, then the charging power into the electric power accumulator is improved, but the estimation accuracy of the engine torque deteriorates and shock occurs
Solution Approach 1:
The patent applies parameter changes by modifying the charge limit value based on the gear ratio of the automatic transmission. When the gear ratio is a high-vehicle-velocity-side gear ratio, the charge limit value is set to a smaller value, and when it is a low-vehicle-velocity-side gear ratio, the charge limit value is set to a larger value. This dynamic parameter adjustment resolves the contradiction by preventing excessive engine torque increase in conditions where estimation accuracy is poor, thereby suppressing shock while still enabling adequate charging power.
2Object-affected harmful factors
If the charge limit value is set to a smaller value to suppress vibrations and noises, then the comfort is improved, but the remaining charge of the electric power accumulator deteriorates
Solution Approach 1:
The patent applies dynamics by making the charge limit value variable according to the gear ratio rather than using a fixed value. The control device dynamically adjusts the charge limit value based on the current gear ratio condition, allowing the system to optimize between suppressing vibrations/noises and maintaining remaining charge. This dynamic approach resolves the contradiction by adapting the charge limit to appropriate operating conditions.
3Object-affected harmful factors
If the charge limit control is performed at all operating conditions, then the shock suppression is improved, but the charging efficiency deteriorates
Solution Approach 1:
The patent applies local quality by implementing charge limit control selectively based on the gear ratio condition rather than uniformly across all operating conditions. The control is applied locally to specific gear ratio ranges (high-vehicle-velocity-side gear ratios) where shock suppression is most needed, while allowing more aggressive charging in other conditions (low-vehicle-velocity-side gear ratios) where estimation accuracy is sufficient. This resolves the contradiction by optimizing the balance between shock suppression and charging efficiency in different operating regions.
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
The solution effectively maintains the remaining charge of the electric power accumulator while preventing shocks by limiting charging power in specific conditions, enhancing torque control accuracy.
Implementation Method 1
a power source control unit performing charge control for increasing a torque of the engine that achieves a drive demand amount so as to achieve a demanded value of a charging power to be charged into the electric-power accumulator by power generation of the electric motor
Data Source
AI summary
A control device of a vehicle, the vehicle having: a power source including an engine and an electric motor; and a power transmission shaft to which the power source is coupled in a power transmittable manner; the vehicle comprising: a power transmission device transmitting a torque of the power source input to the power transmission shaft, to driving wheels; and an electric-power accumulator supplying/receiving electric power to/from the electric motor, the control device comprising: a power source control unit performing charge control for increasing a torque of the engine that achieves a drive demand amount during running of the vehicle in a driving state; and a charge limit control unit performing charge limit control for limiting a charging power in the charge control.