EV Powertrain Torque Map Switching for Stable Speed Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric automobiles with a fixed reduction ratio between the motor and drive wheels face challenges in maintaining constant vehicle speed when traveling environments change, such as road surface gradients or headwinds, requiring adjustments to the accelerator pedal opening, which can lead to increased muscle burden and reduced comfort.
Innovation Solution
A powertrain system that includes a motor, a motive power transmission mechanism, an accelerator pedal opening sensor, a controller, and an operation switch mounted on the steering wheel, allowing the driver to change torque control information without adjusting the accelerator pedal opening, enabling desired torque output regardless of traveling environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the accelerator pedal opening is adjusted to maintain constant vehicle speed when traveling resistance changes, then the vehicle speed stability is improved, but the muscle burden on the driver's right foot increases and operation comfort deteriorates
Solution Approach 1:
The system changes the control parameter from accelerator pedal opening angle to motor output torque directly. By providing multiple torque control modes (first through fourth modes) that define different relationships between pedal opening and torque output, the system maintains vehicle speed stability while allowing the pedal to remain at a comfortable, fixed position regardless of traveling resistance changes.
Solution Approach 2:
The system dynamically switches between different torque control modes based on driving conditions. The controller selects appropriate control information from multiple predefined modes, enabling the motor torque to adapt dynamically to changing traveling resistance while the accelerator pedal position remains static, thus resolving the contradiction between speed stability and operation comfort.
2Device complexity
If the reduction ratio between motor and drive wheels is fixed, then the device complexity is reduced, but the adaptability to different traveling environments deteriorates
Solution Approach 1:
Instead of changing the mechanical reduction ratio, the system changes the control parameters (torque control modes) to adapt to different traveling environments. The controller stores multiple sets of control information corresponding to different modes, allowing the motor torque output to be adjusted according to road gradient, wind resistance, and other environmental factors while maintaining a simple fixed reduction ratio transmission system.
Solution Approach 2:
The single fixed reduction ratio transmission mechanism serves multiple functions by combining it with multiple torque control modes. The same mechanical transmission system can adapt to various traveling conditions through electronic control, making the system universally applicable across different environments without requiring multiple physical transmission configurations.
Data Source
AI summary
A powertrain system for an electric automobile outputs a desired torque from a motor with an angle of an accelerator pedal that is easy for a driver to operate, regardless of traveling environments such as the road surface gradient and the wind direction. The powertrain system includes a paddle switch and a shifter that are mounted to be operable by a driver, and are electrically connected directly or indirectly to an electronic control unit (ECU). The ECU controls, based on a torque control map defining the relationship between an accelerator pedal opening and output torque of a motor in advance, the output torque of the motor according to the accelerator pedal opening, and changes, based on an operation on the paddle switch or the shifter, the torque control map to be used for controlling the output torque of the motor.