Primary-Side Regulation Voltage Accuracy in Continuous Conduction Mode
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Solution Overview
Problem
Conventional primary-side regulation (PSR) flyback converters struggle to accurately regulate output voltage in continuous conduction mode due to sensitivity to secondary inductor current loop resistance, leading to voltage drop and inaccuracy in feedback error signals.
Innovation Solution
A method is introduced to generate a calibrated feedback error voltage by sampling the feedback error signal and current-sense signal at multiple time points during ON and OFF cycles, using piecewise linear approximation and adjustment to compensate for the output inductor current loop resistance and nonlinearity of the rectifier diode, resulting in a feedback error voltage that is less sensitive to these factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional feedback control mechanism is used to regulate output voltage, then voltage regulation is achieved, but accuracy deteriorates due to sensitivity to secondary inductor current loop resistance
Solution Approach 1:
The patent changes the timing parameters of signal sampling, taking multiple samples at different time points during the switching cycle. By sampling the feedback error signal and current sense signal at multiple discrete time points and processing them through piecewise linear approximation, the system transforms the continuous analog feedback into a calibrated digital representation that compensates for resistive voltage drops, thereby improving measurement precision while reducing sensitivity to resistance variations.
2Measurement precision
If piecewise linear approximation and calibration are applied to feedback error signal, then voltage regulation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex analog compensation circuits with digital signal processing. Instead of using additional analog components to compensate for voltage drops, the system uses digital sampling, storage, and piecewise linear approximation algorithms to calculate calibrated feedback error voltage. This substitution of digital processing for analog circuitry achieves high accuracy while keeping the physical device complexity manageable.
Solution Approach 2:
The patent performs preliminary sampling and calibration of the feedback error signal during the switching cycle. By pre-sampling both the feedback error signal and current sense signal at multiple time points and performing piecewise linear approximation before the final control decision, the system prepares accurate voltage representations in advance, reducing the need for complex real-time compensation circuits.
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
This approach improves the accuracy of output voltage regulation by compensating for the voltage drop caused by the secondary inductor current loop resistance, enhancing the precision of voltage control in continuous conduction mode operations.
Implementation Method 1
A magnetic field is generated that transfers energy to secondary winding 13 when main power switch 30 is turned off
Data Source
AI summary
A power converter operates in continuous conduction mode and outputs a regulated output voltage. A feedback-derived signal is used to regulate the output voltage. The feedback-derived signal is sampled at multiple time points during an OFF cycle of a power switch. A current-sense signal is also sampled at one or more time points during an ON cycle of the power switch. The current-sense signal is indicative of an output inductor current of the power converter. A calibrated feedback-derived voltage is then generated based on the multiple voltage samples of the feedback-derived signal and the one or more voltage samples of the current-sense signal. The calibrated feedback-derived voltage is less sensitive to an output inductor current loop resistance than the original voltage samples of the feedback-derived signal. The calibrated feedback-derived voltage also compensates for the nonlinearity of a diode of the output inductor current loop.