Secondary-Side Controller Using Superposition Voltage for Audio Noise
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Solution Overview
Problem
In power converters with grounded capacitors having low electrical series internal resistance, the feedback voltage ripples appear in groups, leading to rapid operational frequency increases and audio noise due to smaller ripples.
Innovation Solution
A secondary controller with a control signal generation circuit and a gate control signal generation circuit that uses a superposition voltage, greater than the feedback voltage ripples, to control the primary side power converter, preventing rapid frequency increases and audio noise by generating a gate pulse signal when the superposition voltage is less than a reference voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the feedback voltage with smaller ripples is used to control the primary controller, then the output voltage control precision is improved, but the operational frequency increases rapidly causing audio noise
Solution Approach 1:
The patent introduces a superposition voltage as an intermediary between the feedback voltage and the primary controller. This superposition voltage is generated by adding a triangular wave signal to the feedback voltage, creating a new control signal that masks the ripple effects while maintaining accurate output voltage control, thereby eliminating audio noise without sacrificing control precision
Solution Approach 2:
The patent changes the parameter of the control signal by superimposing a triangular wave onto the feedback voltage. This parameter modification transforms the control signal characteristics, preventing rapid frequency increases while maintaining the ability to regulate output voltage accurately, thus resolving the contradiction between control precision and audio noise
2Manufacturing precision
If the feedback voltage has smaller ripples, then the output voltage regulation accuracy is improved, but the ripples appear in groups causing instability
Solution Approach 1:
The triangular wave superposition acts as a mediator that stabilizes the control signal. By adding this intermediary signal, the patent prevents the feedback voltage ripples from appearing in groups, maintaining both regulation accuracy and signal stability simultaneously
Solution Approach 2:
The patent applies periodic triangular wave superposition to the feedback voltage. This periodic action masks the ripple grouping effect while preserving the accuracy of output voltage regulation, thereby maintaining both precision and stability
Data Source
AI summary
A secondary controller applied to a secondary side of a power converter includes a control signal generation circuit and a gate control signal generation circuit. The gate control signal generation circuit generates a gate control signal, and generates an injection signal according to the gate control signal. When a superposition voltage is less than a reference voltage, the control signal generation circuit generates a gate pulse control signal, wherein the gate pulse control signal corresponds to an output voltage of the power converter and the injection signal, the gate control signal generation circuit is further used for generating a gate pulse signal according to the gate pulse control signal, and the gate pulse signal is used for making a primary side of the power converter turned on.