Totem Pole PFC Reverse Voltage Detection for Fast Switch Shutdown
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power conversion circuits, particularly totem pole PFC circuits, are vulnerable to damage from reverse currents caused by sudden changes in AC input voltage, leading to potential circuit failure due to the need for high-voltage isolation devices or Hall devices, which increase costs.
Innovation Solution
A control circuit with integrated sampling circuits and a detecting circuit that quickly determines abnormal AC input voltage conditions by comparing sampling voltages, allowing timely shutdown of power switches to prevent reverse current damage without requiring high-voltage isolation or Hall devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-voltage isolation devices or Hall devices are used to protect against reverse current, then circuit reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses a voltage detection circuit as an intermediary to monitor the AC input voltage and generate early warning signals before reverse current occurs. This mediator detects abnormal voltage conditions and triggers protective action without requiring complex high-voltage isolation devices or Hall devices, thus resolving the contradiction between reliability and device complexity
Solution Approach 2:
The patent implements preliminary detection of abnormal AC input voltage conditions before reverse current can damage the circuit. The detection circuit monitors voltage in advance and generates warning signals that trigger protective shutdown, preventing the harmful reverse current from occurring in the first place rather than relying on complex protective devices
2Speed
If fast reverse voltage detection is implemented, then response speed is improved, but circuit complexity increases
Solution Approach 1:
The voltage detection circuit serves as an intermediary that rapidly monitors AC input voltage and immediately generates warning signals when abnormal conditions are detected. This intermediary approach enables fast detection without requiring complex circuitry, as the detection circuit simply monitors voltage levels and triggers protective shutdown when thresholds are exceeded
Solution Approach 2:
The detection circuit is designed to autonomously monitor voltage conditions and automatically generate protective shutdown signals without requiring complex external control systems. The circuit serves itself by detecting its own operational state and initiating protection, achieving fast response with minimal added complexity
Data Source
AI summary
A control circuit for a power conversion circuit having a first input terminal and a second input terminal for receiving an AC input voltage is provided. The control circuit includes a first terminal, a second terminal, a driving terminal, and a detecting circuit. The detecting circuit is coupled to the first terminal and the second terminal to receive a first sampling voltage provided by a first sampling circuit and a second sampling voltage provided by a second sampling circuit. The first sampling circuit is coupled between the first input terminal and a reference ground. The second sampling circuit is coupled between the second input terminal and the reference ground. The detecting circuit provides a control signal to turn off a power switch of the power conversion circuit when it determines that the AC input voltage is abnormal based on the first sampling voltage and the second sampling voltage.