Software Time-Delay Modulation for Fixed-Sampling EMI Reduction
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Solution Overview
Problem
Systems with fixed sampling frequencies face challenges in reducing electromagnetic interference (EMI) due to periodic electric current consumption, which limits their application in high-reliability automotive and medical semiconductors, as conventional methods like Spread Spectrum Clock Generators require additional hardware and complex algorithms, reducing flexibility.
Innovation Solution
A method that modulates a time delay software each cycle of the fixed sampling frequency, using pre-stored modulation profiles or calculations, to distribute EMI spectrum through software-based time delay generation, eliminating the need for additional hardware and complex algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If Spread Spectrum Clock Generator (SSCG) is applied to reduce EMI, then EMI level is reduced, but additional hardware and complex algorithms are required, reducing flexibility
Solution Approach 1:
The patent replaces the hardware-based Spread Spectrum Clock Generator with a software-based time delay modulation mechanism. Instead of using dedicated EMI reduction hardware, the invention implements EMI spectrum spreading through software-controlled timing variations in the interrupt handler, thereby eliminating additional hardware while achieving the same EMI reduction effect
Solution Approach 2:
The system uses its own existing hardware resources (CPU, timer, interrupt controller) to perform EMI reduction functions. The microcontroller's built-in timing mechanisms are leveraged to generate the modulated time delays, making the system self-sufficient and eliminating the need for external EMI reduction hardware
2Object-affected harmful factors
If Spread Spectrum Clock Generator (SSCG) is applied to reduce EMI, then EMI level is reduced, but additional hardware and complex algorithms are required, reducing flexibility
Solution Approach 1:
The patent implements dynamic time delay modulation where the delay amount can be varied in real-time based on operational requirements. The software-based approach allows the modulation characteristics to be changed dynamically without hardware reconfiguration, enabling adaptive EMI reduction that can respond to different operating conditions and frequency ranges
Solution Approach 2:
The invention changes the timing parameters of interrupt handling dynamically to achieve EMI spectrum spreading. By modifying the time delay values in software based on modulation profiles, the system can adjust the EMI reduction characteristics without changing hardware parameters, providing greater versatility
3Object-affected harmful factors
If conventional EMI reduction methods are used, then EMI level is reduced, but system cost increases due to additional hardware
Solution Approach 1:
The patent makes the existing microcontroller system perform multiple functions including both normal operation and EMI reduction. The same CPU and timing resources that execute the main application code are also used to generate the modulated time delays for EMI spectrum spreading, eliminating the need for dedicated EMI reduction hardware and reducing overall system cost
Data Source
AI summary
A method for reducing electromagnetic interference (EMI) in a system that periodically operates with a fixed sampling frequency includes reading a digital signal to which an analog signal received from a sensor is converted, generating a time delay that is modulated each cycle of the fixed sampling frequency with software, starting to execute a digital signal processing algorithm by applying the time delay that is modulated, and transmitting to another device through write of the digital signal. Accordingly, the EMI spectrum is spread through the time delay that is modulated with software, resulting in reduced EMI level.