Boost PFC Controller Eliminates Oscillator
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Solution Overview
Problem
Conventional boost power factor correction (PFC) controllers are complex and expensive due to the need for oscillators and increased pin count for detecting input voltage, which complicates design and increases costs, especially in high power applications.
Innovation Solution
A boost PFC controller using a conductive signal generator and shutdown signal generator to control the switching state of a power switch, allowing for a substantially constant or jitter frequency without the need for input voltage detection, reducing the pin count and enabling a simpler design with an input voltage feed forward circuit for wide voltage range compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If an oscillator is used to generate a saw-tooth wave with fixed clock frequency, then the operating frequency for power switch is fixed, but the device complexity increases
Solution Approach 1:
The patent removes the oscillator component from the conventional PFC controller by using a different control mechanism. Instead of using an oscillator to generate fixed frequency switching, the invention uses a control circuit that directly generates gate drive signals based on current and voltage feedback, thereby achieving frequency stability without the complexity of an oscillator circuit.
Solution Approach 2:
The control circuit automatically adjusts the switching frequency based on the operating conditions through feedback mechanisms. The circuit self-regulates the switching frequency to maintain stable operation without requiring external frequency reference or oscillator components, allowing the system to adapt to different load conditions while maintaining power factor correction performance.
2Measurement precision
If input rectified voltage detection is added to generate reference signal, then the reference signal can be generated accurately, but the pin count of PWM controller increases
Solution Approach 1:
The patent combines the voltage detection function with existing controller resources. Instead of adding separate detection circuits and pins, the invention utilizes the existing current sensing circuitry and control logic to derive the reference signal, merging multiple functions into existing components and avoiding pin count increase.
Solution Approach 2:
The patent introduces an intermediary calculation approach where the reference signal is generated through mathematical processing of existing sensed signals within the controller. By using the relationship between input voltage, output voltage, and power factor requirements, the controller generates the necessary reference signals through internal computation rather than direct voltage detection, eliminating the need for additional detection pins.
3Reliability
If conventional PWM controller with multiple detection circuits is used, then power factor correction can be achieved, but the manufacturing cost increases
Solution Approach 1:
The patent removes unnecessary detection circuits and components from the conventional PFC controller design. By using a simplified control approach that relies on existing components and feedback mechanisms, the invention eliminates redundant circuits that increase manufacturing cost, while maintaining the essential power factor correction functionality.
Solution Approach 2:
The patent employs a control strategy that uses readily available, low-cost components and standard controller resources. Instead of requiring specialized high-precision detection circuits, the invention uses standard sensing elements and digital processing capabilities that are already present in modern PWM controllers, thereby reducing overall manufacturing cost while achieving reliable power factor correction.
Data Source
AI summary
The present invention relates to a power factor correction (PFC) controller. In one embodiment, a boost PFC controller configured in an AC/DC converter can include: (i) a conductive signal generator configured to receive a first sampling signal, and to generate a conductive signal according to the first sampling signal and a first control signal; (ii) a shutdown signal generator configured to compare a second control signal against a third control signal, and to generate a shutdown signal when the second control signal reaches a level of the third control signal; and (iii) a logic controller coupled to the conductive signal generator and the shutdown signal generator to control a switching state of a power switch in AC/DC converter.