Multi-Stage Transmission Control for Electric Vehicles
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Solution Overview
Problem
Conventional control systems for multi-stage transmissions in electric vehicles fail to provide a sufficient feeling of acceleration and stable shifting due to the lack of consideration for the varying driving force characteristics based on vehicle speed during upshift and downshift operations.
Innovation Solution
A control device and method that calculates the driving force of the drive motor when entering shift modes and determines the shift time point based on this calculation, using a controller, vehicle speed sensor, and accelerator position sensor to adjust shifting accordingly, ensuring optimal shifting during upshift and downshift operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional control systems control shifting without considering driving force characteristics, then the transmission structure remains simple, but the feeling of acceleration and stable shifting cannot be secured
Solution Approach 1:
The control system calculates the driving force of the drive motor in real-time based on vehicle speed and torque characteristics, and uses this feedback to determine the optimal shift time point. This feedback mechanism ensures stable shifting by continuously adjusting the shift control decision based on actual driving conditions.
Solution Approach 2:
The control device uses the drive motor's own operating parameters (vehicle speed and torque) to calculate its own driving force characteristics, and autonomously determines the shift time point without requiring external intervention or complex additional sensing systems.
2Speed
If shift time point is determined without calculating driving force, then the control process is simple, but sufficient feeling of acceleration during downshift cannot be achieved
Solution Approach 1:
The control system preliminarily calculates the driving force of the drive motor before making the shift control decision. By performing this calculation in advance based on current vehicle speed and torque characteristics, the system can determine the optimal shift time point that provides sufficient acceleration feeling during downshift.
Solution Approach 2:
The system changes the control parameter from simple speed-based shifting to driving force-based shifting. By calculating driving force as a function of vehicle speed and torque, and using this parameter to determine shift timing, the system achieves better acceleration feeling while maintaining reasonable processing efficiency.
3Power
If multi-stage transmission is installed to improve driving force performance, then the drive motor size can be reduced, but the shifting control becomes more complex
Solution Approach 1:
The control device uses the same drive motor operating parameters (vehicle speed and torque) for both power delivery control and shift timing determination. This multi-functional use of existing sensors and calculations simplifies the overall control system while achieving both power optimization and stable shifting.
Solution Approach 2:
The system changes the shift control approach from fixed gear ratio scheduling to dynamic driving force-based timing. By using the driving force calculation (already performed for power control) to determine shift moments, the system achieves optimal driving force performance across all gear stages without proportionally increasing control complexity.
Data Source
AI summary
A control device for a multi-stage transmission for an electric vehicle is provided. The control device includes a controller configured to calculate a driving force of a drive motor when entering a shift mode and to determine a shift time point based on the calculated driving force, and the multi-stage transmission configured to perform shifting at the determined shift time point.