EV Powertrain Backlash Control via Torque Biasing
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Solution Overview
Problem
Electric vehicles experience mechanical backlash in their powertrains due to gear play, leading to vibrations and noise, which existing filtering techniques partially address but at the cost of reduced responsiveness.
Innovation Solution
A control system with two powertrains, one for forward and one for rearward motion, where each powertrain maintains a minimum torque demand in the same direction to prevent backlash, allowing for smooth operation without reducing vehicle responsiveness by using a vehicle controller to manage torque demands and transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mechanical filtering techniques (e.g., flexible rubber coupling) are used to reduce backlash effects, then vibration and noise are reduced, but powertrain responsiveness is reduced
Solution Approach 1:
The control system continuously monitors the actual torque output of the motor and compares it with the demanded torque. Based on this feedback, the controller dynamically adjusts the motor torque to compensate for backlash effects, maintaining both vibration reduction and responsive performance. The feedback loop enables real-time correction without mechanical filtering.
Solution Approach 2:
The patent replaces mechanical filtering solutions (flexible rubber couplings) with an electronic control system that uses sensor feedback and electronic torque adjustment. This substitution eliminates the need for physical dampers while achieving the same vibration reduction effect without compromising responsiveness.
2Object-affected harmful factors
If engine control systems are used to estimate and minimize backlash effects, then vibration and noise are reduced, but system complexity increases
Solution Approach 1:
The control system utilizes existing sensor data from the motor control system to self-diagnose and self-correct backlash effects. The same sensors that monitor motor operation are repurposed to detect backlash conditions, and the existing torque control capability is used to compensate for it, eliminating the need for additional dedicated components.
3Force
If high transmission ratio (e.g., 10:1) is used in electric vehicles, then torque multiplication is improved, but backlash effects are exacerbated
Solution Approach 1:
The control system applies preliminary counteracting torque adjustments before backlash becomes problematic. By continuously monitoring torque demands and anticipating direction changes, the system pre-adjusts motor torque to maintain gear engagement and prevent backlash from occurring in the first place, rather than merely reacting after vibration occurs.
Data Source
AI summary
A powertrain backlash control system is provided for use with an electric vehicle (EV), where the EV uses at least one powertrain to provide forward vehicle motion and at least one additional powertrain to provide rearward vehicle motion. The control system eliminates backlash by maintaining a positive motor torque within each powertrain when the vehicle is in-gear, thus applying a minimum forward torque demand to the powertrain dedicated to forward motion and applying a minimum reverse torque demand to the powertrain dedicated to rearward motion.