EV Drive Torque Control for Uphill Slip and Rollback Prevention
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Solution Overview
Problem
Existing drive control systems for electric vehicles struggle to simultaneously prevent slip and sliding down on uphill roads, especially when the torque changes suddenly.
Innovation Solution
A drive control apparatus that includes a controller configured to limit the change rate of torque outputted from an electric motor based on two modes: a first limit mode for when the torque is less than a threshold torque, and a second limit mode that is more flexible when the torque is equal to or greater than the threshold torque, during specific traveling states on uphill roads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the torque is increased rapidly to prevent sliding down on uphill roads, then the vehicle can maintain position, but wheel slip occurs
Solution Approach 1:
The control system dynamically adjusts the torque change rate limit based on the current torque level. When torque is below the threshold, a stricter first limit mode is applied to prevent slip. When torque reaches or exceeds the threshold, a more flexible second limit mode is applied to allow faster torque increase for preventing sliding down. This dynamic adjustment resolves the contradiction by adapting the torque control strategy to the current operational state.
Solution Approach 2:
The system changes the parameter of torque change rate limit between two different modes. The first limit mode uses a more restrictive change rate to prevent slip at lower torque levels, while the second limit mode uses a more permissive change rate to enable rapid torque increase at higher torque levels for preventing sliding down. This parameter switching resolves the contradiction by optimizing torque control for different operational phases.
2Reliability
If the torque change rate is strictly limited to prevent slip, then wheel slip is reduced, but the vehicle may slide down on uphill roads
Solution Approach 1:
The control system dynamically switches between two torque change rate limit modes based on the current torque level. At lower torque levels, the first limit mode maintains strict control to prevent slip. When torque reaches the threshold level, the system transitions to the second limit mode which allows faster torque increase to prevent sliding down. This dynamic switching resolves the contradiction by optimizing torque control for different operational phases.
Solution Approach 2:
The system changes the parameter of torque change rate limit between two different modes based on torque magnitude. The first limit mode applies a more restrictive change rate for slip prevention at lower torque, while the second limit mode applies a more permissive change rate for rapid torque buildup at higher torque levels. This parameter adaptation resolves the contradiction between slip prevention and torque response speed.
Data Source
AI summary
A drive control apparatus to be applied to an electric vehicle includes a controller. The controller is configured to limit a change rate of a torque to be outputted from an electric motor of the electric vehicle on the basis of a first limit mode in a case where the torque is less than a threshold torque, in a period of a first traveling state in which the electric vehicle travels on an uphill road where a level of likelihood of an occurrence of a slip is estimated to be equal to or greater than a threshold, and configured to limit the change rate of the torque on the basis of a second limit mode that is more flexible than the first limit mode in a case where the torque is equal to or greater than the threshold torque in the period of the first traveling state.