EV Drivetrain Torque Control for Torsional 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 that includes an electronic control module to adjust throttle commands based on drivetrain natural frequencies, combined with sensor data from wheel and motor output sensors, to control power supplied to the electric motor via an inverter, using filters and real-time adjustments to counter torsional wind-up.
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 before it is applied to the motor, using filters to modify the throttle command based on detected oscillatory behavior. This preliminary adjustment prevents the torque commands that would cause torsional wind-up and oscillations, allowing high torque application while maintaining drivetrain stability.
Solution Approach 2:
The system continuously monitors drivetrain parameters and uses this feedback to dynamically adjust the torque command. By detecting oscillatory behavior and responding in real-time, the control system can maintain both high acceleration performance and drivetrain stability, adjusting torque delivery to prevent torsional wind-up while preserving acceleration capability.
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, the system replaces mechanical solutions with a control-based approach. The electronic control module uses filtering algorithms to adjust torque commands, achieving drivetrain stability through software control rather than mechanical rigidity, thereby avoiding increased complexity and manufacturing cost.
Solution Approach 2:
The system changes the parameters of the torque command signal by applying filters that modify its characteristics. By adjusting the temporal and magnitude parameters of the torque delivery through electronic control, the system achieves drivetrain stability without altering the physical properties or complexity of the mechanical components.
3Stability of the object's composition
If filters are applied to the throttle command to reduce oscillations, then drivetrain stability is improved, but the acceleration response time increases
Solution Approach 1:
The control system applies filtering selectively and partially to the throttle command. Rather than heavily filtering all commands (which would slow response), the system applies just enough filtering to reduce oscillatory behavior while preserving the rapid response needed for acceleration. This balanced approach maintains both drivetrain stability and acceptable acceleration response time.
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 speed oscillations and vibrations by preemptively adjusting torque application, improving drivetrain stability and reducing pulsing or surging during acceleration.
Implementation Method 1
an inverter that controls current supplied to the motor to adjust torque applied by the motor
Data Source
AI summary
A vehicle system includes: a drivetrain that includes an electric motor configured to drive rotation of a wheel; an input device that receives an input and outputs an initial throttle command responsively; an electronic control module that receives the initial throttle command from the input device and outputs an adjusted throttle command, wherein the adjusted throttle command is determined based on a natural frequency of the drivetrain; a first sensor that senses an output of the electric motor; and an inverter having control circuitry that receives the adjusted throttle command from the electronic control module and receives sensor data from the first sensor and controls power supplied to the electric motor based on the sensor data and the adjusted throttle command to counter torsional wind-up of the drivetrain.