Switching Power Supply Control for Radiated Noise Under Load Jitter
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Solution Overview
Problem
Existing switching power supply circuits face challenges in adjusting radiated electromagnetic noise levels due to fluctuations in load or set voltage, particularly when pulse width decreases, leading to increased noise in the radio-frequency band.
Innovation Solution
A switching power supply circuit with a pulse width control unit, drive voltage control unit, and weighting factor calculation unit that adjusts pulse width and drive voltage based on output voltage differences to maintain optimal duty ratio and reduce electromagnetic noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the pulse width of the pulse signal is decreased to improve power efficiency, then the power efficiency increases, but the radiated electromagnetic noise increases in the radio-frequency band
Solution Approach 1:
The patent applies dynamics by making the switching frequency adjustable rather than fixed. The frequency adjustment unit dynamically changes the switching frequency based on operating conditions, allowing the system to optimize between power efficiency and electromagnetic noise reduction. When noise levels are high, the frequency is adjusted to shift the noise spectrum away from problematic radio-frequency bands while maintaining acceptable power efficiency.
Solution Approach 2:
The patent changes the parameter of switching frequency to resolve the contradiction. By adjusting the switching frequency parameter, the system can move the electromagnetic noise spectrum away from sensitive radio-frequency bands while maintaining efficient power conversion. This parameter adjustment allows the system to operate at frequencies that minimize radiated noise without sacrificing power efficiency.
2Object-generated harmful factors
If the switching frequency is adjusted to reduce radiated electromagnetic noise, then the electromagnetic noise decreases, but the power efficiency and output voltage stability may deteriorate
Solution Approach 1:
The patent implements feedback through the frequency adjustment unit that monitors operating conditions and automatically adjusts the switching frequency. This closed-loop control ensures that when the frequency is changed to reduce electromagnetic noise, the system simultaneously maintains output voltage stability by detecting voltage deviations and adjusting frequency accordingly. The feedback mechanism coordinates noise reduction with power efficiency maintenance.
3Adaptability or versatility
If the pulse width is reduced to handle variable load conditions, then the adaptability to load changes improves, but the radiated electromagnetic noise increases
Solution Approach 1:
The patent applies dynamics by enabling the switching frequency to dynamically adapt to load conditions. When the load varies and requires pulse width adjustment that would normally increase noise, the system simultaneously adjusts the frequency to keep the noise spectrum away from radio-frequency bands. This dynamic frequency adaptation maintains load versatility while suppressing electromagnetic noise.
Data Source
AI summary
To provide a switching power supply circuit that can reduce an amount of a radiated electromagnetic noise even in a case of a jitter in a load, a set voltage, or the like. The switching power supply circuit includes: a pulse width control unit configured to control a pulse width of a pulse voltage output from a switching transistor; a drive voltage control unit configured to control a drive voltage for determining a magnitude of the pulse voltage output from the switching transistor; and a weighting factor calculation unit configured to determine a weighting factor for the pulse width and a weighting factor for the drive voltage based on a difference value between a set output voltage value set in advance for a power supply circuit and a measured output voltage value, which is a result of measuring an output voltage of the power supply circuit, and the set output voltage value.