E-Bike Motor Torque Control for Consistent Acceleration
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Solution Overview
Problem
Electric bicycles exhibit undesirable acceleration behavior due to changes in total mass, friction coefficients of the drive train, and varying surroundings conditions, leading to inconsistent driving experiences.
Innovation Solution
A method for controlling the electric motor of an electric bicycle that adapts motor torque based on detected longitudinal acceleration, using sensors to ensure a predefined setpoint acceleration is maintained, independent of the bicycle's mass, friction coefficients, and surroundings, with adjustable thresholds and assistance modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the electric motor provides a fixed drive torque, then the control system is simple, but the acceleration varies with changes in total mass, friction coefficients, and surroundings conditions
Solution Approach 1:
The control unit continuously detects the actual longitudinal acceleration of the electric bicycle and compares it with a reference acceleration value. Based on this feedback, the control unit dynamically adjusts the motor torque to compensate for variations caused by changes in total mass, friction coefficients, and surroundings conditions, thereby maintaining consistent acceleration behavior.
Solution Approach 2:
The system transitions from a static fixed torque control to a dynamic torque adjustment mechanism. The motor torque is continuously adapted based on real-time acceleration feedback, allowing the system to respond to changing operating conditions and maintain desired acceleration performance.
2Reliability
If the motor torque is continuously adapted to maintain predefined acceleration, then the acceleration behavior becomes consistent, but the control complexity and computational requirements increase
Solution Approach 1:
The control unit implements a closed-loop feedback system where the detected longitudinal acceleration is continuously compared with the reference acceleration. The difference between actual and reference acceleration drives the torque adjustment, ensuring reliable and consistent acceleration behavior while using a relatively simple control algorithm.
3Measurement precision
If acceleration sensors and continuous monitoring are added, then the acceleration control precision improves, but the device cost and complexity increase
Solution Approach 1:
The system uses acceleration sensors to provide real-time feedback on the actual longitudinal acceleration. This measurement precision enables the control unit to accurately determine torque adjustments needed to maintain the reference acceleration, improving overall control precision while using standard sensor technology.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method provides consistent and user-defined acceleration behavior, ensuring the electric bicycle maintains a predefined setpoint acceleration with the same pedaling force, regardless of changes in mass, friction, or surroundings, enhancing the driving experience and safety.
Implementation Method 1
a longitudinal acceleration of the electric bicycle in the direction of the longitudinal axis of the electric bicycle is detected with the aid of an acceleration sensor
Data Source
AI summary
A method for controlling an electric motor of an electric bicycle for driving the electric bicycle. The method includes: detecting a longitudinal acceleration of the electric bicycle in the direction of the longitudinal axis of the electric bicycle; and generating a motor torque with the aid of the electric motor as a function of the detected longitudinal acceleration, the motor torque being adapted until a predefined setpoint acceleration is reached or exceeded or undershot.