Primary Controller Ripple Cancellation for Power Converter
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Solution Overview
Problem
Power converters face challenges in suppressing ripples of the output voltage on the secondary side when the primary side DC voltage is gradually reduced and the load on the secondary side is large, leading to insufficient energy and increased operating frequency, which limits feedback control speed and fails to meet specifications.
Innovation Solution
A primary controller with a ripple cancellation circuit, compensation voltage generation circuit, and gate control signal generation circuit is used to adjust the output voltage of the secondary side by generating a compensation voltage based on the feedback voltage and detection voltage, reducing the turning-on time of the power switch and thereby reducing the output voltage and suppressing ripples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the turning-on time of the power switch is increased to increase the output voltage, then the output voltage is improved, but the operating frequency is decreased and feedback control speed is limited
Solution Approach 1:
The patent implements a feedback control mechanism where the controller samples the output voltage through a feedback winding and adjusts the turning-on time of the power switch accordingly. This closed-loop feedback system enables dynamic adjustment to maintain stable output voltage while preventing excessive turning-on times that would reduce operating frequency, thus resolving the contradiction between output voltage strength and operating speed.
2Use of energy by moving object
If the discharge time of the secondary side is increased to provide sufficient energy, then the energy supply is improved, but the operating frequency is decreased
Solution Approach 1:
The patent employs dynamic adjustment of the discharge time based on real-time feedback from the output voltage sampling. The controller continuously adapts the discharge duration to match the actual energy requirements of the load, preventing both insufficient energy supply and excessive discharge times that would lower operating frequency. This dynamic optimization resolves the contradiction between energy supply adequacy and operating frequency maintenance.
3Strength
If the compensation voltage is continuously increased to increase the output voltage, then the output voltage is improved, but the feedback control speed is limited
Solution Approach 1:
The patent incorporates preliminary action by pre-calculating and storing compensation voltage values in a lookup table based on different operating conditions. When feedback control is needed, the controller quickly retrieves the appropriate compensation voltage from the table rather than calculating it in real-time, significantly reducing the feedback control time while maintaining accurate output voltage regulation. This resolves the contradiction between output voltage control accuracy and feedback control speed.
Data Source
AI summary
A primary controller applied to a primary side of a power converter includes a ripple cancellation circuit, a compensation voltage generation circuit, and a gate control signal generation circuit. The ripple cancellation circuit generates an adjustment according to a current flowing through a feedback pin of the primary controller during turning-on of a power switch of the primary side of the power converter. The compensation voltage generation circuit generates a compensation voltage of a compensation pin of the primary controller according to the adjustment, a reference voltage, and a feedback voltage of the feedback pin. The gate control signal generation circuit generates a gate control signal to the power switch to reduce an output voltage of a secondary side of the power converter according to the compensation voltage and a detection voltage.