Hybrid Engine Clutch Synchronization Control Method
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Solution Overview
Problem
Hybrid electric vehicles experience synchronization delays and poor power performance due to delayed lock-up of the engine clutch during mode transitions from EV to HEV mode, leading to inefficient power transmission and fuel efficiency issues.
Innovation Solution
A synchronization control method that adjusts engine speed by controlling motor speed towards a target speed during clutch lock-up, estimating engine speed changes, and calculating motor speed post-change to synchronize engine and motor speeds quickly, thereby facilitating faster clutch lock-up and improved power performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the engine clutch is locked up during transition from EV mode to HEV mode, then power transmission efficiency is improved, but synchronization delay occurs leading to poor power performance
Solution Approach 1:
The system performs preliminary speed synchronization between the engine and motor before locking up the engine clutch. The control unit adjusts the engine speed to match the motor speed in advance, ensuring that when the clutch locks up, there is minimal speed difference, thus preventing synchronization delay and improving power transmission efficiency.
Solution Approach 2:
The control unit continuously monitors the speeds of both the engine and motor, and adjusts the engine speed based on feedback from the speed difference. When the speed difference exceeds a predetermined threshold, the control unit activates speed synchronization control to reduce the difference, ensuring timely clutch lock-up without synchronization delay.
2Ease of operation
If the engine speed is controlled to follow motor speed during synchronization, then clutch lock-up is achieved, but synchronization delay occurs due to sharp motor speed decrease
Solution Approach 1:
Before the motor speed decreases sharply, the control unit predicts the future motor speed and adjusts the engine speed in advance to match the predicted speed. This preliminary adjustment prevents synchronization delay that would otherwise occur due to the sharp decrease in motor speed.
Solution Approach 2:
The control system dynamically adjusts the target engine speed based on real-time motor speed changes. Instead of following a fixed target speed, the engine speed control adapts to dynamic motor speed variations, ensuring continuous synchronization even when motor speed changes sharply.
3Reliability
If the engine clutch lock-up is delayed, then synchronization can be achieved, but power performance deteriorates
Solution Approach 1:
The control unit uses feedback from speed sensors to continuously monitor the speed difference between engine and motor. When the speed difference is within an acceptable range, the control unit commands clutch lock-up, achieving both synchronization accuracy and timely power transmission for optimal power performance.
Solution Approach 2:
The system changes the control parameters by setting a predetermined speed difference threshold as the lock-up condition. When the speed difference falls within this threshold, the clutch is locked up, balancing synchronization accuracy with timely power transmission to maintain high power performance.
Data Source
AI summary
A synchronization control method includes controlling an engine speed to follow a motor speed as a target speed of the engine when synchronization between the engine speed and the motor speed starts according to a demand for the lock-up of the engine clutch while travelling under the EV mode with the engine clutch opened; estimating the engine speed at a time of a transmission gear ratio change at which the motor speed increases and reaches a preset motor speed, wherein the transmission gear ratio change is carried out at the preset motor speed; calculating the motor speed, which is reduced after the transmission gear ratio change, by using the preset motor speed and information on a gear ratio before and after the transmission gear ratio change; and controlling the engine speed by resetting the target speed to the calculated motor speed as a new target speed of the engine.