Motor Driving Apparatus Over-rotation Detection
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Solution Overview
Problem
Existing motor driving systems for electrically assisted vehicles face challenges in accurately detecting over-rotation due to slip, leading to incomplete suppression of motor speed and torque, especially when error factors such as wheel radius, tire deformation, and torque sensor malfunctions are present, resulting in potential over-driving and safety issues.
Innovation Solution
A motor driving apparatus with a controller that compares accumulated running distances from pedal rotation and motor-driven wheel rotation to detect abnormal states, suppressing assist driving by setting torque to zero when over-rotation is detected, using a configuration with a computing unit, assist ratio limiter, and smoothing filter to ensure accurate and timely suppression of motor assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If speed comparison method with fixed margins is used to detect over-rotation, then false detection due to error factors is reduced, but motor speed suppression becomes incomplete and over-driving cannot be prevented
Solution Approach 1:
The patent changes the detection parameter from speed comparison with fixed margins to accumulated distance comparison. By integrating speed over time to obtain distance, the system accumulates small errors rather than comparing instantaneous speeds, allowing for more precise detection of abnormal rotation without requiring large safety margins.
Solution Approach 2:
The patent introduces accumulated distance as an intermediary parameter between speed detection and over-rotation determination. Instead of directly comparing speeds and determining over-rotation, the system uses accumulated distance to bridge the gap, providing a more accurate indicator of actual wheel movement that accounts for detection errors.
2Reliability
If large fixed-rate speed margin is set to account for error factors, then false detection is avoided, but motor rotation cannot be suppressed even when pedal rotation is zero
Solution Approach 1:
The patent changes from using speed as the primary parameter to using accumulated distance. This parameter change eliminates the need for large speed margins because accumulated distance naturally filters out transient errors and provides a more stable basis for detecting true over-rotation events.
Solution Approach 2:
The system performs preliminary accumulation of distance values before making the over-rotation determination. By accumulating distance over a period of time, the system prepares a more reliable metric that reduces false positives and allows for tighter control margins without increasing false detection risk.
3Speed
If acceleration-based detection is used to identify over-rotation, then rapid slip detection is improved, but gradual over-driving with light load cannot be detected
Solution Approach 1:
The patent changes the detection parameter from acceleration to accumulated distance. This allows the system to detect both rapid slips (which create abnormal distance accumulation patterns) and gradual over-driving (which creates subtle but consistent distance deviations), providing comprehensive detection coverage across different over-rotation scenarios.
Data Source
AI summary
A motor driving apparatus includes a driving unit configured to drive a motor according to a torque inputted by a rotation input from a human being; and a controller configured to control driving of the driving unit according to a relationship between an accumulated value of first amounts that correspond to the rotation input from the human being and an accumulated value of second amounts that correspond to rotation of a rotating object driven by the motor. The controller may be further configured to cause the driving unit to suppress driving of the motor when an accumulated difference that is calculated by subtracting the accumulated value of the second amounts from the accumulated value of the first amounts is equal to or less than a predetermined threshold.