Hybrid Vehicle Control Device for High-Rotation Torque Management
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Solution Overview
Problem
In hybrid vehicles equipped with an engine and supercharger, there is a challenge in preventing the engine rotation speed from exceeding the maximum allowed speed, leading to a high-rotation state due to response delays in supercharging pressure, which can result in decreased output torque and power performance.
Innovation Solution
A control device is implemented that includes a high rotation curbing control unit to adjust the engine and first rotary machine operating points, a supercharging pressure decreasing unit to manage supercharging pressure, and a torque compensation unit using the second rotary machine to compensate for torque shortages, ensuring the engine rotation speed remains within safe limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine is controlled to decrease output torque when rotation speed exceeds maximum, then the engine rotation speed can be reduced, but a response delay occurs due to supercharging pressure delay
Solution Approach 1:
The control device predicts future engine rotation speed based on current acceleration and the margin to maximum rotation speed. When the predicted speed exceeds the maximum, the control device proactively decreases engine torque output before the actual speed violation occurs, preventing the need for reactive torque reduction that would cause response delays.
Solution Approach 2:
The control device continuously monitors engine rotation speed, acceleration, and the margin to maximum rotation speed. This feedback loop enables real-time prediction of future speed states and dynamic adjustment of torque output to maintain speed within limits while minimizing response delays.
2Reliability
If the engine rotation speed is controlled to stay within maximum limits, then the engine operates safely, but the output torque may be insufficient due to supercharging pressure response delay
Solution Approach 1:
The first rotary machine acts as an intermediary to compensate for torque loss. When the control device decreases engine torque to prevent speed violation, the first rotary machine increases its torque output to make up for the deficiency, ensuring total vehicle power output remains sufficient while engine speed stays within safe limits.
3Power
If the engine operates close to maximum rotation speed, then power output is maximized, but the risk of exceeding maximum speed increases
Solution Approach 1:
By predicting future engine rotation speed based on current acceleration and margin to maximum, the control device takes preliminary action to reduce torque when violation is anticipated, allowing the engine to operate closer to maximum speed without actually exceeding it, thus maximizing power output while maintaining reliability.
Data Source
AI summary
Since a supercharging pressure from a supercharger decreases when an actual rotation speed difference is equal to or less than a margin rotation speed difference, a response delay of an engine torque due to a response delay of the supercharging pressure in a high rotation curbing control unit can be appropriately curbed. A shortage of the engine torque with respect to a required engine torque due to a decrease in the supercharging pressure by a supercharging pressure decreasing unit is compensated for using an torque of a second rotary machine. Accordingly, it is possible to curb a decrease in power performance due to a decrease in the supercharging pressure and to prevent an engine rotation speed from falling into a high-rotation state in which the engine rotation speed exceeds a maximum rotation speed.