Electric Bicycle Torque-Based Motor Control
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Solution Overview
Problem
Conventional chainless electric bicycles lack the acceleration sense provided by a chain, as the speed of the bicycle does not change when a high torque is applied to the pedal, leading to a less engaging riding experience.
Innovation Solution
An electric bicycle with a power generator, battery, motor, pedal speed sensor, motor driver, and electronic control unit that estimates pedal torque and adjusts motor current based on pedal speed and torque, allowing the wheel speed to change in response to applied torque, mimicking the acceleration feel of a chained bicycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the wheel speed is controlled to follow the pedal speed in a chainless electric bicycle, then the structure is simplified and the chain problems are eliminated, but the acceleration sense is lost when torque is applied to the pedal
Solution Approach 1:
The control system dynamically adjusts the relationship between pedal input and wheel speed based on real-time conditions. When torque is detected during acceleration, the system temporarily allows wheel speed to exceed pedal speed proportionally, creating the acceleration sense. This dynamic adjustment resolves the contradiction by making the system behavior adaptive rather than fixed.
Solution Approach 2:
The system changes the control parameter from strictly following pedal speed to allowing proportional overshoot based on torque detection. By detecting torque through current sensing and calculating the difference between actual and target speed, the system adjusts the wheel speed parameter dynamically to provide acceleration feedback while maintaining the simplified chainless structure.
2Extent of automation
If the wheel speed strictly follows the pedal speed, then the control is simple, but the bicycle speed does not change when high torque is applied to the pedal
Solution Approach 1:
The system implements feedback by continuously monitoring the difference between actual wheel speed and target wheel speed (based on pedal speed). When torque is applied and the actual speed lags behind the target, the system detects this discrepancy and allows the wheel speed to exceed the target temporarily, providing the acceleration sense while maintaining relatively simple control logic.
3Object-generated harmful factors
If no chain is used in the electric bicycle, then the chain-related problems are eliminated, but the acceleration sense provided by chain tension is lost
Solution Approach 1:
The system replaces the mechanical chain tension feedback with an electronic control mechanism. Instead of relying on physical chain tension to provide acceleration sense, the system uses sensors and controllers to detect torque application and programmatically adjust wheel speed to simulate the acceleration feel, eliminating chain problems while preserving the sensory feedback.
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 system provides an acceleration sense similar to a chained bicycle by dynamically adjusting wheel speed in response to pedal torque, enhancing the riding experience by changing speed based on pedal effort.
Implementation Method 1
a power generator configured to generate a voltage by driving of a pedal
Implementation Method 2
a battery configured to store the voltage generated by the power generator
Implementation Method 3
a motor mounted on at least one of a front wheel and a rear wheel and configured to provide a rotational force to a mounted wheel by power supplied from the battery
Data Source
Figure 1
Figure 2~4
Figure 5
AI summary
Disclosed herein are an electric bicycle and a method of controlling the same. The electric bicycle according to an embodiment of the present disclosure includes: a power generator configured to generate a voltage by driving of a pedal; a battery configured to store the voltage generated by the power generator; a motor mounted on at least one of a front wheel and a rear wheel and configured to provide a rotational force to a mounted wheel by power supplied from the battery; a pedal speed sensor configured to sense a speed of the pedal; a motor driver configured to drive the motor; and an electronic control unit configured to drive the motor according to a pedal speed sensed by the pedal speed sensor and to control a current supplied to the motor being driven based on a pedal torque applied to the pedal.