Dynamic Gear Ratio Control for Smooth EV Gear Shifts
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Solution Overview
Problem
Electric vehicles with multiple motors experience drivability issues during gear shifts due to changes in vehicle acceleration, necessitating a system to control vehicle motion and distribute motor torque effectively across axles.
Innovation Solution
A method and system that dynamically computes gear ratios and motor torques using an optimization process based on kinematic equations and constraints to maintain constant acceleration and torque ratio during gear shifts, employing a vehicle motion controller to manage the gearbox operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional gear shift control is used in multi-speed electric vehicles, then the gear shift operation is simple, but the vehicle acceleration changes during gear shift causing drivability issues
Solution Approach 1:
The patent implements dynamic gear ratio computation during gear shift operations, transitioning from static to dynamic control. The system continuously adjusts gear ratios based on real-time vehicle state to maintain constant acceleration, resolving the contradiction between operational simplicity and acceleration stability.
Solution Approach 2:
The system dynamically changes the gear ratio parameter during gear shift to compensate for acceleration variations. By adjusting the gear ratio in real-time based on computed optimal values, the system maintains stable vehicle acceleration while preserving ease of operation through automated control.
2Stability of the object's composition
If dynamic gear ratio computation is implemented to maintain constant acceleration, then vehicle acceleration stability is improved, but the control system complexity increases
Solution Approach 1:
The vehicle motion controller is designed to perform multiple functions: it manages motor torque distribution, computes optimal gear ratios, and maintains acceleration stability. By consolidating these functions into a single controller, the system achieves acceleration stability without proportionally increasing overall system complexity.
Solution Approach 2:
The patent replaces complex mechanical gear shift mechanisms with computational control. Instead of relying on purely mechanical solutions for maintaining acceleration stability, the system uses electronic computation and control algorithms to dynamically adjust gear ratios, reducing mechanical complexity while achieving the desired stability.
3Adaptability or versatility
If motor torque is dynamically adjusted during gear shift, then torque distribution across axles is improved, but the computation and control complexity increases
Solution Approach 1:
The system performs preliminary computation of optimal torque distribution and gear ratios before executing the gear shift operation. By pre-calculating the required torque adjustments based on predicted vehicle state, the system achieves adaptive torque distribution while reducing real-time computational complexity during the actual gear shift.
Solution Approach 2:
The system implements feedback control by continuously monitoring vehicle acceleration and motor torque, then adjusting torque distribution accordingly. This closed-loop control enables adaptive torque management across axles while keeping computation complexity manageable through iterative adjustment based on measured performance.
Data Source
AI summary
A vehicle includes a system and method of operating a gearbox of the vehicle. The vehicle includes an interface for entering a desired vehicle acceleration and a processor. The system includes a processor. The processor is configured to receive the desired vehicle acceleration, create an objective function that relates the desired vehicle acceleration to a torque, perform an optimization process on the objective function to determine the torque, and apply the torque to the vehicle to achieve the desired vehicle acceleration.