Hybrid EV Shift Torque Distribution for Input Speed Tracking
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Solution Overview
Problem
Hybrid electric vehicles face challenges in securing a consistent and sophisticated shift feeling during shifting due to disturbing factors such as viscosity changes in transmission oil, hydraulic response deviations, and torque errors from the drive source, which can prevent the input end of the transmission from reaching its target speed.
Innovation Solution
A shift control method for hybrid electric vehicles that distributes speed control torque to multiple motors, ensuring the input end of the transmission follows its target speed by determining the appropriate distribution based on the engine clutch lock-up status and motor charging limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If intervention control is performed to reduce kinetic energy of the input shaft during shifting, then clutch protection and efficient shifting are improved, but the speed of the input end of the transmission may not reach the target speed due to disturbing factors
Solution Approach 1:
The control method continuously compares the actual speed of the input end of the transmission with the target speed and adjusts the torque of the drive source accordingly. This closed-loop feedback control ensures that the input shaft speed reaches the target speed despite disturbing factors such as oil viscosity changes and hydraulic response deviations during intervention control.
Solution Approach 2:
The torque of the drive source (particularly the electric motor) is dynamically adjusted based on the speed difference between actual and target speeds. By changing the torque parameter in real-time, the system compensates for disturbing factors and ensures the input shaft reaches the target speed while maintaining clutch protection.
2Speed
If active shift control is performed by controlling the torque of the drive source, then the speed of the input end of the transmission follows the target speed, but the system complexity increases due to multiple motors and control coordination
Solution Approach 1:
The speed control torque is segmented and distributed to multiple drive sources (electric motor and engine) based on their respective capabilities and operational states. The control system divides the total torque requirement between the second motor connected directly to the transmission and the first motor connected through the engine clutch, simplifying the control of each individual motor while achieving overall speed control.
Solution Approach 2:
The control system is designed to handle multiple drive sources (electric motor and engine) with a unified control strategy. The same speed control algorithm applies regardless of which drive source is active, and the system automatically adapts to different operational modes (electric-only, hybrid, engine-only), reducing the need for separate control logic for each motor.
3Ease of operation
If speed control torque is distributed to multiple motors, then consistent and sophisticated shift feeling is secured, but the control precision requirements increase due to torque distribution coordination
Solution Approach 1:
The system continuously monitors the actual speed of the input end of the transmission and compares it with the target speed. This feedback information is used to adjust the torque distribution between multiple motors in real-time, ensuring that the combined torque output achieves the desired speed control with high precision despite the complexity of coordinating multiple drive sources.
Data Source
AI summary
A shift control method of a hybrid electric vehicle includes: determining a speed control torque based on a result of comparing a speed of an input end of a transmission with a target speed of the input end of the transmission according to a shift signal; distributing the speed control torque to a second motor connected directly to the input end of the transmission; and distributing a residual speed control torque to a first motor connected selectively to the second motor through an engine clutch based on whether the engine clutch is locked up when the speed control torque is greater than a charging limit torque of the second motor.