Primary-Side AC/DC Error Amplifier with Dual AC/DC Feedback Paths
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Solution Overview
Problem
The existing primary-side feedback controlled AC/DC converters suffer from poor stability and low output voltage precision due to the limitations of their error amplifiers, resulting in significant voltage errors between full and empty load conditions.
Innovation Solution
An improved error amplifier is introduced, comprising a transconductance amplifier and a summing module with both direct current and alternating current paths, where the alternating current path provides fast response to adjust output voltage quickly with low precision, while the direct current path reduces equivalent output errors, enhancing overall output voltage precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional error amplifier with single path is used, then the circuit is simple, but the output voltage precision is low and stability is poor
Solution Approach 1:
The error amplifier is divided into two independent paths: AC path and DC path. Each path processes different components of the error signal independently. The AC path handles dynamic voltage adjustments while the DC path handles steady-state precision, allowing both speed and accuracy requirements to be met without compromising circuit simplicity
Solution Approach 2:
The error amplifier transitions from a static single-path design to a dynamic multi-path design where different paths are activated based on the nature of the error signal. The AC path provides fast dynamic response for voltage adjustments, while the DC path provides precise steady-state regulation, creating a dynamically adaptive system
2Speed
If the error amplifier responds quickly to adjust output voltage, then the response speed is fast, but the output voltage precision deteriorates
Solution Approach 1:
The response function is segmented into two distinct paths: the AC path provides fast response for dynamic adjustments by handling alternating current components of the error signal, while the DC path provides precision for steady-state regulation by handling direct current components. This segmentation allows each path to be optimized for its specific function without compromise
Solution Approach 2:
The AC path provides excessive response speed for dynamic adjustments, while the DC path provides excessive precision for steady-state conditions. By combining these two paths, the system achieves both fast response and high precision simultaneously, with each path performing partial functions that together exceed the requirements
Data Source
AI summary
An error amplifier, a controller using the error amplifier, and a primary-side feedback controlled AC/DC converter using the controller are discussed. When the output voltage of the primary-side feedback controlled AC/DC converter according to present invention changes, the alternating current path enjoys a fast response and adjusts the output voltage quickly with a lower precision, avoiding large voltage fluctuate, then the direct current path functions slowly to reduce equivalent output error. In such a way, the output voltage precision is enhanced while the stability of the primary-side feedback controlled AC/DC converter is maintained.