EV Motor Torque Control for Virtual Shifting in Drift Mode
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Solution Overview
Problem
Existing electric vehicles lack a technique to provide drivers with the driving emotion, fun, excitement, and direct connection typically experienced in vehicles with multi-speed transmissions, especially during drift mode operations where controlling rear-wheel slip is challenging due to fast torque response.
Innovation Solution
A torque control apparatus and method that detects vehicle driving states and generates a motor torque command to implement virtual shifting in drift mode, by determining a shift intervention torque and varying the motor torque with a slope based on vehicle states, ensuring a seamless transition without disrupting drift control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If virtual shift function is implemented in drift mode by generating shift intervention torque, then virtual shift feeling is provided to driver, but rear-wheel slip control becomes difficult and drift ease of operation deteriorates
Solution Approach 1:
The patent applies dynamics by making the torque control strategy adaptive and changeable based on driving mode. The controller dynamically adjusts torque distribution between front and rear wheels, and modifies torque transition characteristics during virtual shifting in drift mode versus normal driving mode, allowing the system to optimize performance for each specific operating condition
Solution Approach 2:
The patent applies local quality by implementing different torque control strategies for different wheels and different driving modes. Specifically, during drift mode virtual shifting, the system applies asymmetric torque control where rear-wheel torque is prioritized to maintain slip, while front-wheel torque is controlled separately, creating localized torque characteristics tailored to each wheel's function in drift conditions
2Speed
If motor torque range is set to entire available range for fast torque response, then torque responsiveness is improved, but rear-wheel slip control precision deteriorates during drift mode
Solution Approach 1:
The patent applies partial action by not using the entire available motor torque range simultaneously for both wheels. Instead, it selectively applies torque to rear wheels to induce and control slip, while modulating front wheel torque separately. The torque transition during virtual shifting is also applied partially and gradually rather than abruptly, maintaining precision control
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting torque distribution ratios between front and rear wheels, and by controlling the rate of torque change during virtual shifting. The system modifies torque parameters (magnitude, distribution, transition rate) based on detected driving conditions to maintain optimal slip control precision
3Ease of manufacture
If shift intervention torque is generated during virtual shifting in drift mode, then virtual shift feeling is implemented, but torque transition disrupts drift control and smoothness deteriorates
Solution Approach 1:
The patent applies beforehand cushioning by preparing and pre-calculating torque transition paths before executing virtual shifting during drift mode. The controller anticipates the need for smooth torque transitions and applies gradual torque changes rather than abrupt shifts, cushioning the transition to maintain drift state stability and prevent disruption
Data Source
AI summary
A torque control apparatus in an electric vehicle includes a driving information detector that detects information indicating a vehicle driving state, a controller that generates a motor torque command for satisfying a demand torque based on vehicle driving information including the detected information, and a motor that is controlled according to the generated motor torque command. The controller determines whether there is a virtual shift demand according to the vehicle driving state in a drift mode, stops, when there is the virtual shift demand, determination and generation of a shift intervention torque for implementing a virtual shift feeling and determines a motor torque as a value that varies with a slope from a target torque before shift to a target torque after shift during virtual shifting in the drift mode, and generates the motor torque command using the determined motor torque as a command value.