Flyback Converter Primary-Side Load Compensation
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Solution Overview
Problem
Conventional power conversion systems face challenges in effectively offsetting the change in output voltage due to output current variations caused by the resistance of the output cable, leading to poor regulation, especially at no load or light load conditions, and result in higher standby power loss.
Innovation Solution
A digitally-controlled nonlinear load compensation mechanism that generates a compensation current based on the output current, which adjusts the reference voltage to maintain constant output voltage without requiring an external pin for compensation, thereby canceling out the voltage change caused by the output cable resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional feedback mechanisms are used to regulate output voltage, then output voltage can be controlled, but the change in output voltage due to output current variations cannot be effectively offsetted, leading to poor regulation at no load or light load conditions
Solution Approach 1:
The patent implements a feedback mechanism where the auxiliary winding voltage is sampled and fed back to the controller chip. The controller adjusts the primary-side switching parameters based on this feedback to compensate for output voltage changes caused by load variations and cable resistance, thereby improving voltage regulation without requiring additional external compensation components.
Solution Approach 2:
The controller chip performs load compensation functions internally using its own resources. It calculates the compensation amount based on the auxiliary winding feedback and automatically adjusts the primary-side switching parameters, eliminating the need for external compensation circuits and reducing standby power loss while maintaining reliable output voltage regulation.
2Reliability
If conventional primary-side sensing and regulation are used, then output voltage can be controlled, but cross-regulation issues between controller chip consumption power and output power cannot be addressed
Solution Approach 1:
The patent dynamically changes the primary-side switching parameters (such as switching frequency or duty cycle) based on the load conditions detected through auxiliary winding feedback. This allows the system to adapt to different operating modes and resolve cross-regulation issues between controller consumption power and output power, improving both voltage control and adaptability.
3Reliability
If external compensation pins and components are used for load compensation, then output voltage regulation can be improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the load compensation function into the existing primary-side sensing and regulation circuitry. The controller chip integrates the compensation logic and uses the auxiliary winding feedback directly, eliminating the need for separate external compensation pins and components. This reduces device complexity and cost while maintaining improved output voltage regulation.
Solution Approach 2:
The auxiliary winding serves multiple functions: it provides feedback for output voltage regulation, enables load compensation, and supports cross-regulation management. This multi-functional approach eliminates the need for dedicated compensation components, reducing overall system complexity while achieving reliable voltage regulation across different operating conditions.
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 achieves very low standby power loss and improved output voltage regulation by directly addressing the cross-regulation issues between the controller chip's consumption power and the output power, reducing costs and enhancing the power conversion system's efficiency.
Implementation Method 1
the voltage of the auxiliary winding 114 maps the output voltage on the secondary side
Data Source
AI summary
System and method for regulating an output voltage of a power conversion system. The system includes a sampling component located on a chip configured to receive an input voltage through a terminal. The sampling component is configured to sample the input voltage and generate a sampled voltage. Additionally, the system includes an error amplifier configured to process information associated with the sampled voltage and a threshold voltage and generate a first output signal, and a first signal generator configured to generate a second output signal and one or more third output signals. Moreover, the system includes a comparator configured to receive the first output signal and the second output signal and generate a comparison signal, and a gate driver directly or indirectly coupled to the comparator and configured to generate a drive signal based on at least information associated with the comparison signal.