E-Bike PMSM Wheel Locking for Theft Detection and Prevention
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Solution Overview
Problem
Electric bicycles are vulnerable to theft due to their reliance on external power to rotate the wheels, lacking effective theft prevention mechanisms.
Innovation Solution
An electric bicycle theft prevention system utilizing a permanent magnet synchronous motor (PMSM) that controls the d-axis current to lock the wheels and generates an alarm when theft is detected, preventing wheel rotation with external power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electric bicycle uses a motor to rotate the wheels, then the bicycle can move forward efficiently, but the bicycle becomes vulnerable to theft through external power application
Solution Approach 1:
The system applies preliminary anti-action by detecting theft attempts before the bicycle can be moved away, and immediately activating the alarm unit to deter the thief. The sensor unit continuously monitors for unauthorized movement, and upon detection, the alarm is activated to prevent the theft from succeeding.
Solution Approach 2:
The patent replaces traditional mechanical locking systems with an electronic sensing and alarming system. Instead of using physical locks that can be picked or broken, the system uses sensor units to detect movement and electronic alarm units to deter thieves, substituting mechanical security with electronic security measures.
2Device complexity
If the electric bicycle lacks external locking devices, then the structure remains simple, but the theft prevention capability is insufficient
Solution Approach 1:
The sensor unit serves multiple functions: it detects wheel rotation, determines whether the bicycle is in motion, identifies theft attempts, and triggers the alarm system. This multi-functionality allows the system to maintain simplicity while providing comprehensive theft prevention without requiring separate dedicated components for each function.
Solution Approach 2:
The system provides self-service theft prevention by automatically detecting unauthorized movement through the sensor unit and immediately activating the alarm without requiring user intervention. The bicycle monitors itself and responds to theft attempts autonomously, eliminating the need for the user to manually engage locks or security measures.
3Measurement precision
If the sensor unit continuously monitors wheel rotation, then theft detection accuracy improves, but energy consumption increases
Solution Approach 1:
The sensor unit performs periodic monitoring of wheel rotation rather than continuous monitoring, checking at regular intervals to detect changes in wheel position. This periodic action maintains theft detection accuracy by capturing movement events while reducing energy consumption compared to continuous monitoring, as the sensor can enter low-power states between measurement cycles.
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
Effectively prevents theft by locking the wheels and alerting the user to unauthorized movement, even without additional external locking devices, thereby reducing material and mental damage from theft.
Implementation Method 1
The sensor unit may be configured to detect a position of a rotation shaft or a rotor of the motor unit
Implementation Method 2
the controller controls magnitudes of a d-axis current and a q-axis current of the motor unit to be predetermined values
Data Source
AI summary
An electric bicycle theft prevention system for preventing theft of an electric bicycle according to an embodiment of the present disclosure includes a motor unit, a sensor unit, a controller, and an alarm unit. The motor unit is a permanent magnet synchronous motor (PMSM), and is configured to rotate wheels of the electric bicycle by receiving power from an electric storage unit. The sensor unit is configured to detect a position of a rotation shaft or a rotor of the motor unit. The controller is configured to control the motor unit and the sensor unit. The alarm unit is configured to generate an alarm by an electrical signal of the control unit. In addition, when a theft prevention function is activated in an unused state of the electric bicycle, the controller monitors a sensor value of the sensor unit to detect a movement of the electric bicycle.An electric bicycle theft prevention control method of an electric bicycle theft prevention system for preventing theft of an electric bicycle according to an embodiment of the present disclosure includes a theft prevention function activating operation, an electric bicycle movement detecting operation, an alarm operating and wheel locking operation, an alarm operation and wheel lock cancelling operation. In the theft prevention function activating operation, a theft prevention function of the electric bicycle is activated by a user in an unused state of the electric bicycle. In the electric bicycle movement detecting operation, a controller monitors a sensor value of a sensor unit to detect a movement of the electric bicycle after the theft prevention function is activated. In the alarm operating and wheel locking operation, when the controller determines that the electric bicycle is moving in the electric bicycle movement detecting operation, an alarm is operated and wheels of the electric bicycle are locked. In the alarm operation and wheel lock cancelling operation, the controller detects whether the sensor value of the sensor unit is greater than a predetermined set value in the alarm operating and wheel locking operation, and when it is detected that the sensor value of the sensor unit is smaller than the predetermined set value, the alarm operation and wheel lock are cancelled.