CVT Phase Compensation Control for Vibration and Stability
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Solution Overview
Problem
Continuously variable transmissions in vehicles face instability in transmission ratio control, leading to insufficient damping and potential vibration due to insufficient lead compensation, which can result in unstable control systems and vehicle behavior.
Innovation Solution
A control device for continuously variable transmissions that employs phase lead compensation and phase delay compensation, with a phase compensation on/off determination unit to dynamically adjust and stabilize the compensation based on the vehicle's operating state, ensuring stability and suppressing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead compensation amount is increased to improve damping performance and suppress longitudinal vibration, then vibration suppression is improved, but high frequency gain becomes larger causing the transmission ratio control system to become unstable
Solution Approach 1:
The phase compensation is divided into two separate components: phase lead compensation and phase delay compensation. This segmentation allows independent control of each component's effect, enabling the system to achieve vibration suppression through lead compensation while using delay compensation to counteract excessive high-frequency gain and maintain stability.
Solution Approach 2:
The system dynamically adjusts the lead and delay compensation amounts based on operating conditions. By changing the compensation parameters according to the vehicle state, the system can optimize vibration suppression performance while preventing control instability across different operating ranges.
2Ease of operation
If lead compensation is fixed for peak value frequency to simplify control, then control simplicity is improved, but damping performance becomes insufficient under varying vehicle operating states
Solution Approach 1:
The phase compensation amounts for both lead and delay components are made variable based on vehicle operating conditions rather than being fixed. This dynamic adjustment allows the system to maintain optimal damping performance across different operating states while using a standardized control structure.
Solution Approach 2:
The system uses feedback from vehicle state sensors to dynamically adjust the lead and delay compensation amounts. This feedback mechanism ensures that the compensation parameters are continuously optimized based on actual operating conditions, maintaining both simplicity and effectiveness.
3Reliability
If phase delay compensation is continuously applied to maintain stability, then control stability is improved, but response speed decreases during unstable traveling states
Solution Approach 1:
The phase delay compensation is applied periodically or conditionally rather than continuously. The control system switches between applying and not applying delay compensation based on the detected traveling state, providing rapid response during unstable states while maintaining stability during normal operation.
Data Source
AI summary
A control device for a continuously variable transmission performs feedback control so that an actual transmission control value becomes a target transmission control value. The control device for a continuously variable transmission includes a phase lead compensation unit configured to perform phase lead compensation of the feedback control, a phase delay compensation unit configured to perform phase delay compensation of the feedback control, and a phase compensation on/off determination unit configured to stop the phase delay compensation by the phase delay compensation unit when an unstable traveling state of a vehicle is detected, and to restore the phase delay compensation when a traveling state of the vehicle has changed.