All-Wheel EV Torque Synchronization for Smooth Secondary Axle Engagement
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Solution Overview
Problem
Existing all-wheel drive vehicles with electric motors face challenges in achieving optimal performance, efficiency, and comfort due to delayed coupling of secondary axles, leading to uncomfortable jolts and torque gradients during dynamic driving modes.
Innovation Solution
A control device with an electronic control unit dynamically adjusts the target torque distribution between primary and secondary electric motors based on driver input, activating the secondary motor with a predefined delay to synchronize torque settings, thereby optimizing axle torque distribution for improved performance and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the secondary motor is activated immediately to provide sporty performance response, then the driving performance and acceleration response are improved, but torque gradients and uncomfortable jolts occur due to unsynchronized torque distribution
Solution Approach 1:
The control device determines a magnetization time for the secondary motor before full torque activation. The primary motor provides the required total target torque during this preliminary magnetization phase, and only after this delay are the target torques of both motors synchronously set according to an all-wheel drive distribution factor. This preliminary action prevents torque gradients and jolts while maintaining sporty acceleration response.
Solution Approach 2:
The system dynamically adjusts the activation strategy of the secondary motor based on driving conditions. In dynamic driving modes with steep accelerator pedal gradients, the system activates the secondary motor with a predefined magnetization delay to achieve synchronized torque distribution. This dynamic adaptation allows sporty performance while preventing uncomfortable torque gradients.
2Use of energy by moving object
If the secondary motor is kept deactivated to optimize efficiency, then energy consumption is reduced, but driving performance and traction are compromised in dynamic situations
Solution Approach 1:
The system performs preliminary magnetization of the secondary motor with a predetermined delay time before full torque activation. This allows the motor to be ready for immediate contribution without requiring continuous activation, thus maintaining energy efficiency while ensuring driving performance is available when needed through the primary motor during the magnetization phase.
3Object-affected harmful factors
If the secondary motor is activated with a delay to synchronize torque settings, then driving comfort is improved by reducing jolts, but acceleration response time is increased
Solution Approach 1:
The control device implements a predefined magnetization time as a preliminary action before full torque activation. During this magnetization delay, the primary motor provides the required total target torque. This preliminary magnetization ensures smooth torque synchronization and driving comfort while the primary motor maintains acceleration performance during the transition period.
Data Source
AI summary
A control device for operating a roadbound all-wheel vehicle having a first electric drive motor assigned to a primary axle and a second electric drive motor assigned to a secondary axle, including a control unit configured such that, when a defined dynamic driving mode of the driver is identified based on the driver request gradient during a operating mode with the first motor activated and the second motor deactivated for a predefined time window, an overall setpoint moment characteristic predefined by a new driver request is ascertained. This is set, in accordance with an axle distribution factor that is likewise predefined, by reducing the setpoint moment of the primary motor and by activating and increasing the setpoint moment of the secondary motor, even when the predefined overall setpoint moment characteristic lies below a maximum possible moment of the primary motor.