Electromagnetic Lock Power Control Circuit Using PWM
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Solution Overview
Problem
Existing electromagnetic door locking systems waste energy by constantly supplying power to the electromagnet when the door is closed and not being opened, and re-energize unnecessarily after a fixed delay, leading to inefficiency and increased electricity costs.
Innovation Solution
An electromagnetic door locking system that uses a power control circuit with pulse-width modulation to adjust the current to the electromagnet based on the door's position and unauthorized attempts, switching to a high holding force mode only when needed, and maintaining a constant current flow through the magnetic core windings during the 'off' portion of the cycle to reduce energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electromagnet is constantly powered to prevent unauthorized opening, then the door security is maintained, but energy consumption increases significantly
Solution Approach 1:
The electromagnet is powered periodically rather than continuously. The system uses a timer to cycle the electromagnet between powered and unpowered states, checking for door position at intervals. This periodic operation dramatically reduces energy consumption while maintaining security through regular monitoring and immediate re-powering when the door is detected open.
Solution Approach 2:
The system uses the door's own position state to control power consumption. When the door is closed, the system infers security is maintained and powers down the electromagnet. When the door opens, the system automatically detects this state change and re-energizes the electromagnet, making the system self-regulating based on its operational needs.
2Loss of time
If the electromagnet is re-energized after a fixed delay period, then sufficient time is provided for passage through the door, but energy is wasted when the door remains open beyond the delay period
Solution Approach 1:
The system continuously monitors door position and uses this feedback to control electromagnet power state. Instead of using a fixed timer that wastes energy, the system checks the actual door position state and only re-energizes the electromagnet when the door is detected to be open, eliminating unnecessary energy consumption during extended door-open periods.
3Force
If full power is supplied to the electromagnet at all times, then the magnetic holding force is maximized, but energy efficiency deteriorates
Solution Approach 1:
The system applies partial power to the electromagnet only when necessary for brief periods during door monitoring cycles, rather than maintaining full power continuously. This partial action approach provides sufficient magnetic holding force during critical moments while dramatically improving overall energy efficiency through reduced power duration.
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 achieves significant energy savings by minimizing power usage when the door is closed and not being opened, and ensures secure locking only when necessary, reducing environmental impact and electricity costs while maintaining effective door security.
Implementation Method 1
an energizable electromagnet is affixed to the door or the door frame for electromagnetically attracting an armature
Implementation Method 2
the electromagnet is energized, the armature is attracted to the electromagnet
Implementation Method 3
providing power to the magnetic coil(s) in an adjustable pulse-width modulated (PWM) wave form
Implementation Method 4
Transform Electrical Energy to Magnetic Energy
Data Source
AI summary
An energizable electromagnet of a door locking system is affixed to the door or the door frame for electromagnetically attracting an armature affixed to the other. A power control circuit is configured to selectively energize the electromagnet using a pulse-width modulated current cycle wherein two levels of magnetic force may be selectively applied to the system. A door position sensor is configured to provide a first communication signal to the power control circuit when the door is in a closed position. A second communication signal is provided when the door is not in the closed position. The electromagnet is energized at the lower level of magnetic force when the power control circuit receives the first communication signal and at the higher level of magnetic force only when an unauthorized attempt to open the door is initiated.