Electric Axle Torque Control for Drivetrain Wind-Up
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Solution Overview
Problem
Electric vehicles experience torsional wind-up and oscillatory behavior due to the elasticity of drivetrain components, leading to unwanted vibrations and oscillations during acceleration, which conventional systems fail to effectively mitigate.
Innovation Solution
A vehicle system with an electric axle assembly and sensors that adjust the torque applied by the electric motor based on real-time feedback from motor and wheel sensors to counter torsional wind-up, using an inverter's control circuitry to manage power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high torque is applied instantaneously by the electric motor during acceleration, then acceleration performance is improved, but torsional wind-up and oscillatory behavior occur in the drivetrain
Solution Approach 1:
The control system preemptively adjusts the torque command from the accelerator pedal before it is fully applied to the motor. By modifying the throttle command in advance based on predicted drivetrain conditions, the system prevents torsional wind-up from occurring in the first place, rather than reacting after oscillations begin
Solution Approach 2:
The system continuously monitors motor output and wheel output through sensors, comparing the actual drivetrain response against the commanded torque. This feedback loop allows the control system to detect early signs of torsional wind-up and dynamically adjust the torque application to maintain drivetrain stability while preserving acceleration performance
2Stability of the object's composition
If the drivetrain components are made more rigid to reduce torsional wind-up, then drivetrain stability is improved, but the system complexity and manufacturing cost increase
Solution Approach 1:
Instead of modifying the mechanical drivetrain components to be more rigid or adding mechanical dampers, the system replaces the mechanical solution with an electronic control approach. The control circuitry actively manages torque delivery to compensate for drivetrain elasticity, achieving stability without altering the physical drivetrain structure
Solution Approach 2:
The system dynamically changes the torque parameter delivered to the motor based on real-time drivetrain conditions. By adjusting the magnitude and timing of torque application through electronic control, the system compensates for the inherent elasticity of drivetrain components without requiring structural modifications
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
The system effectively mitigates low-frequency oscillations and vibrations by preemptively adjusting torque direction and magnitude, enhancing vehicle stability and comfort during acceleration.
Implementation Method 1
an inverter that supplies power to the electric motor and includes control circuitry that controls power supplied to the electric motor based on the sensed output of the electric motor and the sensed output of the wheel to adjust operation of the electric motor
Data Source
AI summary
A vehicle system includes: an electric axle assembly with an electric motor, a gear system, a differential, a half shaft, and a wheel; an input device that receives an input and outputs an initial throttle command; an electronic control module that receives the initial throttle command from the input device and outputs an adjusted throttle command; a first sensor that senses an output of the electric motor; a second sensor that senses an output of the wheel; and an inverter having control circuitry that receives the adjusted throttle command from the electronic control module and receives sensor data from the first and second sensors. The control circuitry controls power supplied to the electric motor based on the adjusted throttle command and the sensor data from the first and second sensors.