Power Supply Frequency Control for Audible Noise Suppression
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Solution Overview
Problem
Conventional power supply devices experience noise issues due to switching frequencies of PFC and LLC converters being close, leading to poor user experience.
Innovation Solution
A power supply device incorporating a first and second bridge rectifier, a coupling inductive element, a power switch element, a transformer, a resonant capacitor, and an auxiliary control circuit, where the second power switch element is enabled or disabled based on the switching frequency relative to the clock voltage's central frequency to suppress noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the switching frequency of PFC and LLC converter are kept close for compact design, then device size is reduced, but noise is generated that is easily discernable by human ear
Solution Approach 1:
The patent implements dynamic frequency adjustment by introducing a frequency adjustment module that dynamically changes the switching frequency of either the PFC or LLC converter based on real-time detection. This dynamic adaptation allows the system to maintain compact size while avoiding fixed frequency ranges that cause audible noise, thereby resolving the contradiction between device size and noise generation.
Solution Approach 2:
The patent changes the frequency parameter of the switching power supply system by detecting the switching frequency and adjusting it to fall outside the human audible range (20Hz-20kHz). This parameter modification allows the system to maintain close frequencies for compact design while eliminating audible noise by operating in ultrasonic or subsonic frequency ranges.
2Object-generated harmful factors
If the switching frequency is adjusted to suppress noise, then noise levels are reduced, but frequency stability may be affected
Solution Approach 1:
The patent implements a feedback mechanism where a frequency detection module continuously monitors the switching frequency, and this detected frequency is fed back to the frequency adjustment module. This closed-loop feedback system automatically adjusts the frequency to maintain it outside the audible range while ensuring frequency stability through continuous monitoring and correction, thereby resolving the contradiction between noise suppression and frequency stability.
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
Effectively suppresses resonant noise within a specific frequency range, improving user experience by maintaining stable output voltage and reducing noise levels.
Implementation Method 1
The coupling inductive element receives the first rectified voltage and the second rectified voltage. The first power switch element selectively couples the coupling inductive element to a ground voltage according to the clock voltage. The first output stage circuit, which is coupled to the coupling inductive element, is configured to generate an internal voltage.
Implementation Method 2
The transformer includes a main coil, a first secondary coil, and a second secondary coil. A leakage inductor and a magnetizing inductor are built in the transformer. The main coil is coupled through the leakage inductor to the switch circuit.
Implementation Method 3
The resonant capacitor is coupled to the magnetizing inductor.
Data Source
AI summary
A power supply device for suppressing noise includes a first bridge rectifier, a second bridge rectifier, a coupling inductive element, a first power switch element, a first output stage circuit, a switch circuit, a transformer, a second output stage circuit, and an auxiliary control circuit. The first bridge rectifier and second bridge rectifier generate a first rectified voltage and a second rectified voltage according to a first input voltage and a second input voltage. The coupling inductive element receives the first rectified voltage and the second rectified voltage. The switch circuit generates a control voltage. The second output stage circuit generates an output voltage. The auxiliary control circuit includes a second power switch element. The second power switch element is coupled to the coupling inductive element, and is selectively enabled or disabled according to the control voltage.