DC-DC Converter Switching Frequency Modulation for Radio Noise Suppression
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Solution Overview
Problem
On-board DC-DC converters generate abnormal noise due to a power spectrum component at the repetition frequency, which can be demodulated as sound by radios, causing discomfort to vehicle passengers.
Innovation Solution
The power conversion device changes the switching frequency in a predetermined pattern over time, ensuring the repetition frequency does not coincide with the frequency bands that can be demodulated as sound by radios, thereby suppressing the abnormal noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If switching frequency is changed in a predetermined pattern and repeated at every repetition time, then the maximum value of the power spectrum can be suppressed and noise interfering with radios can be reduced, but a power spectrum is newly generated at the repetition frequency that can be demodulated as sound by a radio, causing abnormal noise
Solution Approach 1:
The patent changes the repetition time parameter of the switching frequency modulation to shift the repetition frequency away from the radio demodulation frequency band. Specifically, the repetition time is set so that the repetition frequency (inverse of repetition time) does not coincide with frequencies that can be demodulated as sound by radios, thereby eliminating abnormal noise while maintaining the noise suppression benefits of frequency modulation.
2Power
If repetition time is set to disperse switching frequencies, then the maximum power spectrum value is suppressed, but the repetition frequency component introduces noise that can be demodulated as sound
Solution Approach 1:
The patent optimizes the repetition time parameter to achieve a dual benefit: it maintains sufficient frequency dispersion to suppress the maximum power spectrum value while simultaneously ensuring that the resulting repetition frequency falls outside the radio demodulation frequency band, thereby preventing abnormal noise generation.
Data Source
AI summary
A converter is provided as a power conversion device. The converter includes a switching circuit that performs switching on the basis of switching signals; and a control circuit that changes switching frequency of switching signals in a predetermined pattern with the elapse of time, and repeats the changes in switching frequency in the predetermined pattern at every repetition time. The converter sets the repetition time such that a repetition frequency that is the inverse of the repetition time does not coincide with a frequency band that can be demodulated as sound by a radio that receives radio broadcasts.