Two-Stage Power Supply Inductor Coupling for Audible Noise Suppression
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Solution Overview
Problem
Conventional power supplies with a two-stage structure, comprising a boost power factor corrector and an LLC converter, generate audible noise due to simultaneous energy buildup when the switching frequencies are mismatched, particularly at higher output loads.
Innovation Solution
A power supply design that includes a boost circuit and an LLC converter, where the first inductor of the LLC converter is inductively coupled with the boost inductor to delay the zero-voltage switching of the second switch, ensuring the turn-on time of the second switch lags behind the power switch, thereby reducing noise by preventing simultaneous energy buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the switching frequency of the LLC converter is lowered to meet higher output power requirements, then the output power capability is improved, but audible noise is generated due to simultaneous switching with the boost power factor corrector
Solution Approach 1:
The patent applies preliminary action by detecting the switching frequency of the boost power factor corrector beforehand and using this information to dynamically adjust the switching frequency of the LLC converter. The control device obtains the switching frequency information from the boost circuit and uses it as a reference to set the LLC converter's switching frequency, ensuring that the LLC converter switches at a different time than the boost circuit. This preventive approach avoids simultaneous switching and eliminates audible noise while maintaining high output power capability.
2Object-generated harmful factors
If the switching frequency of the LLC converter is increased to reduce noise, then audible noise is reduced, but the output power capability is reduced
Solution Approach 1:
The patent implements dynamics by making the switching frequency of the LLC converter dynamically adjustable based on the operating conditions. Instead of using a fixed switching frequency, the control device continuously monitors the boost circuit's switching frequency and dynamically adjusts the LLC converter's switching frequency to maintain an optimal difference between the two. This dynamic adjustment allows the system to achieve noise reduction at various power levels without sacrificing output power capability, as the switching frequencies adapt to changing load conditions.
3Device complexity
If a fixed switching frequency is used for the LLC converter, then the control complexity is reduced, but simultaneous switching with the boost circuit occurs causing audible noise
Solution Approach 1:
The patent applies feedback by creating a closed-loop control system where the switching frequency information from the boost power factor corrector is fed back to the LLC converter's control device. The control device uses this feedback information to continuously adjust the LLC converter's switching frequency, ensuring that it remains different from the boost circuit's switching frequency. This feedback mechanism automatically prevents simultaneous switching and audible noise without requiring complex manual tuning or fixed frequency settings, achieving noise reduction while maintaining relatively simple control architecture.
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
The solution effectively suppresses dynamic noise by synchronizing the turn-on times of the switches, minimizing audible noise generation and improving operational efficiency.
Implementation Method 1
The first inductor is inductively coupled with the boost inductor to obtain a first energy
Data Source
AI summary
Provided is a power supply including a boost circuit and an LLC converter. The LLC converter includes a first inductor, a first switch, and a second switch. The LLC converter controls the first switch and the second switch according to the zero-voltage switching rule, so as to convert a boosted power supply provided by the boost circuit to an output power. The first inductor is inductively coupled with a boost inductor of the boost circuit to obtain the first energy. In response to the first energy, a time point when a first terminal and a second terminal of the first switch have zero voltage difference is delayed, such that a turn-on time point of the second switch lags behind a turn-on time point of a power switch of the boost circuit.