Chainless E-Bike Pedal Torque Control for Battery-Free EPAC Riding
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Solution Overview
Problem
Chainless electric bicycles need a method to meet the Electric Power Assist Cycle (EPAC) standard, which requires propulsion without a battery, as users must reach 10 km/h through pedal operation alone, and existing systems lack a mechanism to create a pedal load similar to traditional bicycles.
Innovation Solution
A pedal control device and method that detect DC link voltage, pedal speed, and wheel speed, adjusting pedal and wheel torque to maintain a stable DC link voltage, allowing the electric bicycle to be driven without a battery by controlling the generator and motor torques based on speed differences and voltage comparisons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a chainless electric bicycle uses only motor power without pedals, then the structure is simplified and no chain is needed, but users feel awkward and cannot meet EPAC standards requiring pedal operation
Solution Approach 1:
The generator is designed to serve dual functions: acting as a brake to provide pedaling resistance when the user pedals, and as a power source to generate electricity when pedaling. This multi-functionality allows the system to maintain simplicity while enabling genuine pedaling interaction required by EPAC standards
Solution Approach 2:
The system uses the pedaling action itself to generate the electrical energy needed to power the motor that assists pedaling. The generator converts mechanical energy from pedal rotation into electrical energy, creating a self-sustaining energy loop that eliminates the need for external battery power
2Ease of operation
If a generator is connected to the pedal to create load, then pedaling feeling similar to traditional bicycles is achieved, but the system cannot operate without a battery to meet EPAC standards
Solution Approach 1:
The system dynamically adjusts the electrical load on the generator based on pedaling speed and desired motor assistance level. By changing the electrical parameter (load current), the system controls the mechanical resistance felt by the user, creating realistic pedaling feedback while regulating power flow to eliminate battery requirements
Solution Approach 2:
The control device continuously monitors pedaling speed and adjusts the generator's electrical load accordingly. This feedback mechanism ensures that the pedaling resistance remains appropriate across different speeds while optimizing energy recovery, enabling battery-less operation under EPAC conditions
3Ease of operation
If the generator is controlled to provide braking load, then realistic pedaling resistance is achieved, but DC link voltage becomes unstable without battery buffering
Solution Approach 1:
The system dynamically adjusts the generator's electrical load based on real-time operating conditions including pedaling speed, wheel speed, and DC link voltage levels. This dynamic control allows the generator to provide appropriate braking load while simultaneously regulating power flow to maintain voltage stability without battery buffering
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
This solution enables chainless electric bicycles to operate without a separate battery, maintaining stable DC link voltage and providing a pedaling experience similar to traditional bicycles, thus meeting EPAC standards.
Implementation Method 1
a generator configured to be driven by and apply a pedal torque to a pedal of the bicycle and provide an electrical direct current (DC voltage)
Implementation Method 2
a motor configured to drive a wheel of the bicycle at a predefined wheel speed and/or wheel torque
Data Source
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AI summary
A pedal control device and method for a chainless electric bicycle are provided. A pedal control device includes a detector (10) configured to detect a DC link voltage, a pedal speed, and a wheel speed (S410, S510), and an adjuster (120) configured to adjust at least one of a pedal torque (S620, S630) and a wheel torque based on the pedal speed and the wheel speed (S410, S510), and configured to compare the detected DC link voltage with a target voltage (S610), and further adjust at least one of the pedal torque (S620, S630) and the wheel torque based on a voltage comparison result (S420).