Totem-Pole PFC Circuit with Backup Overvoltage Sampling
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Solution Overview
Problem
The existing power factor correction (PFC) circuits with totem-pole PFC configurations face issues with overvoltage protection when the output sampling circuit is abnormal, leading to potential damage to the power supply.
Innovation Solution
A power factor correction circuit is designed with an alternating current input circuit, a totem-pole PFC circuit, input and output sampling circuits, and a PFC control protection circuit. The circuit uses separate sampling voltages for PWM control and overvoltage protection, allowing for effective overvoltage protection when the output sampling circuit is abnormal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the PWM control circuit and OVP circuit share the same sampling voltage from the output sampling circuit, then the device complexity is reduced, but the reliability deteriorates because neither circuit can work normally when the output sampling circuit is abnormal
Solution Approach 1:
The patent divides the sampling function into two independent paths: one sampling circuit for PWM control and another sampling circuit for OVP protection. This segmentation ensures that abnormality in one sampling path does not affect the other, resolving the reliability issue while maintaining reasonable complexity through functional separation.
Solution Approach 2:
The patent introduces an intermediary mechanism by using the input sampling circuit's second sampling voltage as a backup for OVP detection when the output sampling circuit fails. This intermediary sampling path provides redundant protection capability without requiring a completely separate independent system.
2Reliability
If a separate input sampling circuit is added to provide backup sampling voltage for overvoltage protection, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The input sampling circuit is designed to serve multiple functions: it provides sampling voltage for PWM control during normal operation and simultaneously serves as a backup for OVP protection when the output sampling circuit fails. This multi-functionality reduces the need for completely separate dedicated circuits, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent merges the OVP sampling function with the existing input sampling circuit rather than creating a completely separate OVP sampling system. By combining multiple functions into existing circuit structures, the patent achieves improved reliability while minimizing the increase in overall device complexity.
Data Source
AI summary
A power factor correction (PFC) circuit includes an alternating current input circuit, a totem-pole PFC circuit, an input sampling circuit, an output sampling circuit, and a PFC control protection circuit. A first output terminal of the alternating current input circuit is respectively connected to a first input terminal of the totem-pole PFC circuit and a first input terminal of the input sampling circuit.