Dual-Motor EV Transmission Torque Control for Cold Lubricant Heating
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Solution Overview
Problem
Existing electric vehicle control technologies do not effectively address the issue of increased viscosity of transmission lubricants at low temperatures, leading to frictional forces and deteriorated electric efficiency.
Innovation Solution
An electric vehicle control device that controls multiple electric motors to apply a heating component torque to one motor while subtracting it from another to manage torque distribution, promoting transmission lubricant heating and reducing electric cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If one electric motor is operated at high torque to heat the transmission, then the transmission temperature increases, but the overall vehicle propulsion torque is reduced
Solution Approach 1:
The control device dynamically adjusts torque distribution between the first and second electric motors based on transmission temperature conditions. During heating periods, the system dynamically allocates torque to optimize both heating efficiency and propulsion requirements, rather than using a fixed torque distribution strategy
Solution Approach 2:
The system changes operational parameters by adjusting the torque commands to each motor based on transmission temperature feedback. When heating is required, the control device modifies the torque parameters to increase heating component torque while maintaining overall system performance
2Temperature
If heating component torque is increased to warm the transmission, then transmission lubricant viscosity decreases, but electric motor efficiency deteriorates
Solution Approach 1:
The system uses the electric motors' own operational characteristics to generate heat for the transmission lubricant. By controlling the motors to operate in a manner that produces beneficial heating effects, the system self-services the heating requirement without external energy input, thereby maintaining overall energy efficiency
Solution Approach 2:
The control device converts what would normally be wasted energy (motor losses that generate heat) into a beneficial heating effect for the transmission lubricant. During cold conditions, the system intentionally allows or enhances these losses to warm the lubricant, transforming a potential inefficiency into a useful function
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively heats transmission lubricants, reducing frictional forces and maintaining electric vehicle efficiency by optimizing torque distribution between motors.
Implementation Method 1
at a low temperature of the transmission, the viscosity of the liquid medium of the transmission increases, and a frictional force is applied to the gears
Implementation Method 2
the viscosity of the liquid medium of the transmission increases, and a frictional force is applied to the gears
Data Source
AI summary
An electric vehicle control device that controls a vehicle traveling via a transmission coupled to a plurality of electric motors as a drive source, the electric vehicle control device including: a controller configured to control a first electric motor and a second electric motor that are in contact with a first transmission and a second transmission incorporating a liquid medium, respectively, in which in a heating period in which the first transmission or the second transmission is heated, the controller drives and controls one of the first electric motor and the second electric motor with a powering torque obtained by increasing a heating component torque to a required torque of the electric motor, and controls an other of the first electric motor and the second electric motor with a torque obtained by subtracting the heating component torque from the required torque of the electric motor.