Electric Vehicle Torque Control for Pitching Vibration
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Solution Overview
Problem
Conventional methods for suppressing drive wheel slippage in electric vehicles, which involve reducing and restoring electric motor torque, can cause significant pitching vibration, leading to degraded ride comfort due to resonance between torque variation and vehicle pitching frequency.
Innovation Solution
An electrically driven vehicle equipped with electric motor control means that reduces and restores torque while using pitching detection to vary the torque restoration amount based on detected vibration amplitude, ensuring the natural frequency of pitching vibration differs from the torque variation frequency, thus preventing resonance and maintaining stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the torque of the electric motor is reduced and restored to suppress drive wheel slippage, then the slippage is suppressed, but the pitching vibration of the vehicle increases due to resonance between torque variation frequency and natural pitching frequency
Solution Approach 1:
The patent applies dynamics by making the torque restoration amount variable rather than fixed. The control system dynamically adjusts the torque restoration amount based on detected pitching vibration amplitude, allowing the system to adapt to changing vehicle conditions and avoid resonance while maintaining effective slippage suppression.
Solution Approach 2:
The patent implements feedback by using pitching detection means to continuously monitor the vehicle's pitching vibration amplitude and using this information to adjust the torque restoration amount. This closed-loop control ensures that torque variations do not excite resonant frequencies, thereby suppressing pitching vibration while maintaining slippage control effectiveness.
2Reliability
If the torque variation of the electric motor is significant to suppress slippage, then the slippage suppression effect is improved, but the natural frequency of pitching vibration approaches the torque variation frequency causing resonance
Solution Approach 1:
The system dynamically adjusts the torque restoration amount based on real-time detection of pitching vibration amplitude. When pitching vibration is detected, the restoration amount is reduced to avoid exciting resonant frequencies, while still maintaining sufficient torque variation to suppress slippage. This dynamic adaptation preserves both slippage suppression effectiveness and vehicle stability.
Solution Approach 2:
The patent changes the parameter of torque restoration amount based on detected vibration conditions. By modifying this key parameter dynamically, the system prevents the torque variation frequency from matching the natural pitching frequency, thereby avoiding resonance while maintaining adequate slippage suppression capability.
3Speed
If the torque of the electric motor is rapidly restored after slippage suppression, then the response time is reduced, but the pitching vibration amplitude significantly increases degrading ride comfort
Solution Approach 1:
The system dynamically adjusts the torque restoration speed based on detected pitching vibration amplitude. When pitching vibration is detected, the restoration speed is reduced to prevent exciting resonant frequencies and increasing vibration amplitude. When no pitching vibration is present, faster restoration is permitted, improving response time without compromising ride comfort.
Solution Approach 2:
The patent changes the torque restoration parameter dynamically based on vibration detection results. This allows the system to optimize the balance between response speed and ride comfort by adjusting restoration parameters according to real-time vehicle conditions, preventing resonance while maintaining adequate response performance.
Data Source
AI summary
Provided is an electrically driven vehicle that is capable of suppressing drive wheel slippage without increasing the pitching vibration of the vehicle. The electrically driven vehicle having electric motors (1, 4), drive wheels (3, 6) driven by the electric motors respectively, and, when at least one of the drive wheels slips, an electric motor control device (40) for reducing the torque of at least one of the electric motors that drives the at least one wheel slipped, and for restoring the torque of the at least one electric motor when the slippage is stopped includes a pitching detection device (26) for detecting the amplitude of pitching vibration to which the vehicle is subjected. The amount of torque of the at least one electric motor to be restored by the electric motor control device over a predetermined period of time after the slippage is stopped varies depending on whether or not the amplitude A detected by the pitching detection device is greater than an assessment value A1.