Door System PWM Frequency Adjustment for EMI Reduction
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Solution Overview
Problem
Existing door systems with automatic drive devices emit high-frequency radiation due to fixed pulse width modulated signal switching frequencies, which can interfere with nearby electronic devices, such as merchandise security systems, leading to disruptive influences.
Innovation Solution
An adjustment device is integrated into the door system to dynamically adjust the switching frequency of the pulse width modulated signal, allowing it to be synchronized with the operating frequencies of nearby electronic devices, preventing interference and ensuring only authorized personnel can make adjustments through a display and input device, potentially with remote interface options.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the switching frequency of the pulse width modulated signal is fixed, then the control device operates stably, but electromagnetic interference with nearby electronic devices occurs
Solution Approach 1:
The patent applies the dynamics principle by transforming the fixed switching frequency into a variable one. The control device now dynamically adjusts the switching frequency of the pulse width modulated signal based on the operating frequencies of nearby electronic devices, allowing the system to adapt and avoid interference while maintaining stable operation.
Solution Approach 2:
The patent implements parameter changes by modifying the switching frequency parameter of the pulse width modulated signal. Instead of using a fixed frequency, the system varies the switching frequency to ensure it and its harmonics do not overlap with the operating frequencies of nearby electronic devices, thereby eliminating electromagnetic interference.
2Object-affected harmful factors
If the switching frequency is adjusted to avoid interference, then electromagnetic compatibility improves, but system complexity increases
Solution Approach 1:
The patent applies feedback by implementing a frequency detection and adjustment mechanism. The control device detects the operating frequencies of nearby electronic devices and uses this information to adjust the switching frequency of the pulse width modulated signal, creating a closed-loop system that automatically avoids interference without requiring complex external intervention.
Solution Approach 2:
The control device performs self-service by autonomously adjusting its own switching frequency based on the detected electromagnetic environment. The system monitors nearby electronic devices and automatically modifies its operating parameters to avoid interference, eliminating the need for external calibration or complex manual configuration.
3Adaptability or versatility
If frequency adjustment functionality is added, then adaptability to different electronic devices improves, but ease of operation decreases
Solution Approach 1:
The control device performs self-service by autonomously adjusting its own switching frequency based on the detected electromagnetic environment. The system monitors nearby electronic devices and automatically modifies its operating parameters to avoid interference, eliminating the need for external calibration or complex manual configuration.
Solution Approach 2:
The patent implements preliminary action by pre-programming the control device with frequency adjustment algorithms and interference avoidance logic. The system is prepared in advance to detect and respond to electromagnetic interference, allowing it to automatically adapt to different electronic devices without requiring manual setup or complex user intervention during operation.
Data Source
Figure 1
AI summary
The system (1) has an automatic driving device (7) for driving a door leaf (2), where the device comprises an electronic control device (11) and an electrical driving motor. The control device emits a pulse width modulated signal for controlling the driving motor, where switching frequency of the pulse width modulated signal is adjusted to working frequency of electronic equipments in goods protection system (9) by an adjusting mechanism (12). The adjusting mechanism exhibits a display device, an input mechanism and an interface.