Synchronous Switching Controller for Power Converter Noise Reduction
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Solution Overview
Problem
Existing power converter control circuits face difficulties in synchronizing switching signals across multiple converters due to varying switching frequencies, leading to noise, instability, and jitter, especially under changing load conditions.
Innovation Solution
A synchronous control circuit that includes a synchronous input circuit, soft start circuit, enable circuit, oscillation circuit, and signal converter to generate and synchronize the switching signal with a synchronous input signal, allowing immediate synchronization and adjustment of the switching frequency and duty cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the switching frequency is varied in response to load changes to save power losses, then power efficiency is improved, but synchronization with other power converters becomes difficult
Solution Approach 1:
The control circuit preliminarily determines a base switching frequency before load changes occur. This base frequency serves as a reference that maintains synchronization capability while allowing frequency variation within a predetermined range in response to load changes, thus preserving both power efficiency and synchronization reliability
Solution Approach 2:
The patent applies parameter changes by allowing the switching frequency to vary within a predetermined range around a base frequency. The control circuit adjusts the switching frequency based on load conditions while constraining it within limits that ensure synchronization with other converters, resolving the contradiction between power saving and synchronization
2Speed
If fast synchronization of the switching signal is implemented, then synchronization speed is improved, but jitters and acoustic noises are generated during phase locking
Solution Approach 1:
The patent applies dynamics by implementing a dynamic synchronization process where the switching frequency is initially adjusted quickly to match the synchronous signal, then gradually stabilized. The control circuit dynamically controls the switching frequency to converge to the target frequency while minimizing oscillations, thus achieving fast synchronization without excessive jitters or acoustic noises
3Reliability
If synchronization of the switching signal is implemented under variable load conditions, then synchronization capability is improved, but supply voltage stability deteriorates during turning-on
Solution Approach 1:
The control circuit performs preliminary actions by establishing the switching frequency synchronization before full power operation begins. The base switching frequency is determined in advance, and the synchronization is achieved during the startup phase, preventing voltage instability during the turning-on process while maintaining synchronization capability under variable load conditions
Data Source
AI summary
A switching control circuit having a synchronous input for the synchronization of power converters is provided. It includes a synchronous input circuit for receiving a synchronous input signal. An oscillation circuit is connected to the synchronous input circuit for generating an oscillation signal in response to the synchronous input signal. A signal converter is coupled to receive a feedback signal of the power converter for modulating the oscillation signal in response to the feedback signal for achieving power savings. The oscillation signal is connected for enabling the switching signal of the power converter. The switching signal can be synchronized with the synchronous input signal immediately after the synchronous input signal is inputted. Otherwise, the switching signal will be running free.