PFC Frequency Modulation Circuit for Peak Load Saturation Control
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Solution Overview
Problem
Existing power supply frequency modulation circuits struggle to efficiently manage peak load requests without saturating the internal inductor of the power factor correction (PFC) circuit, leading to inefficiencies and potential acoustic issues.
Innovation Solution
A frequency modulation circuit that includes a frequency adjustment circuit and a switch control signal generation circuit, which alter the internal equivalent resistance and capacitance to adjust the switch frequency of the PFC circuit power stage in response to peak load requests, thereby preventing inductor saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the winding turns of the PFC inductor are increased to avoid saturation during peak load, then the inductor can handle higher current, but the size of the choke increases
Solution Approach 1:
The patent applies dynamic frequency modulation to the PFC circuit, adjusting the switching frequency based on load conditions. During peak load, the frequency is increased to prevent inductor saturation without requiring physical changes to the inductor dimensions, thus avoiding the need to increase choke size while maintaining reliability
Solution Approach 2:
The invention changes the operating parameter (switching frequency) of the PFC circuit dynamically. By modulating the frequency according to load demands, the system can handle peak loads without saturation while keeping the inductor physical dimensions constant, resolving the contradiction between reliability and volume
2Reliability
If the cross-sectional area of the choke is increased to avoid saturation during peak load, then the inductor can handle higher current, but the size of the choke increases
Solution Approach 1:
The system dynamically adjusts switching frequency based on real-time load conditions. During peak load events, frequency modulation allows the existing choke area to handle higher currents without saturation, eliminating the need to increase the cross-sectional area while maintaining reliability
3Reliability
If the air gap of the choke is increased to decrease the inductance value and avoid saturation, then peak load handling improves, but PFC efficiency decreases
Solution Approach 1:
Instead of permanently changing the inductance value through air gap adjustment, the invention dynamically changes the switching frequency parameter. This allows the system to handle peak loads by frequency modulation while maintaining the optimal air gap setting for efficiency, thus improving peak load handling without energy loss
4Reliability
If the material of the choke is changed from iron material to soft saturation material to avoid saturation, then peak load handling improves, but PFC efficiency decreases and acoustic impact is created
Solution Approach 1:
The invention avoids material changes entirely by using frequency modulation as a parameter change strategy. The existing iron material choke operates at dynamically adjusted frequencies, preventing saturation and maintaining both high efficiency and low acoustic impact while handling peak loads
Data Source
AI summary
A frequency modulation circuit of a power supply includes a frequency adjustment circuit and a switch control signal generation circuit coupled to the frequency adjustment circuit. The switch control signal generation circuit generates a plurality of switch control signals to the frequency adjustment circuit based on a peak load request, in order to control a plurality of switches in the frequency adjustment circuit. In response to these switch control signals, an internal equivalent resistance and an internal equivalent capacitance of the frequency adjustment circuit are altered. By adjusting the internal equivalent resistance and internal equivalent capacitance of the frequency adjustment circuit, a switch frequency of a PFC circuit power stage of the power supply is controlled by the frequency adjustment circuit, in order to meet the peak load request.