DC-DC Converter Pulse Frequency Modulation Light Load Noise
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Solution Overview
Problem
Existing DC-DC converters experience localization of switching operations at light loads, leading to noise and ripple in the output voltage, which affects power conversion efficiency.
Innovation Solution
A DC-DC converter system that employs pulse frequency modulation control at light loads, incorporating an oscillation circuit, a skipping circuit to skip the oscillation frequency signal, and a pulse width modulation control circuit to manage the ON and OFF states of transistors based on the skipped signal, thereby avoiding localization of switching operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the DC-DC converter operates using PWM method at heavy load, then power conversion efficiency is maintained, but at light load the switching operation localizes causing noise and ripple in output voltage
Solution Approach 1:
The patent applies dynamics by making the switching frequency variable rather than fixed. The oscillation circuit generates a frequency signal that dynamically adjusts based on load conditions, allowing the converter to transition between PWM and PFM modes smoothly without localization effects, thereby reducing noise and ripple while maintaining efficiency.
Solution Approach 2:
The patent changes the parameter of switching frequency from a fixed value to a variable parameter that adapts to load conditions. By using an oscillation circuit to generate frequency signals and a skipping circuit to modulate them, the system achieves parameter changes that prevent localization and reduce output voltage ripple at light loads.
2Loss of energy
If the DC-DC converter switches to PFM method at light load, then power conversion efficiency is improved, but switching operation localization occurs causing noise generation
Solution Approach 1:
The patent implements periodic action through the oscillation circuit that generates regular frequency signals. This periodic oscillation ensures that switching operations occur at predictable intervals rather than localizing at specific points, thereby reducing noise while maintaining the energy efficiency benefits of PFM operation at light loads.
Solution Approach 2:
The patent uses feedback mechanisms where the output voltage is monitored and fed back to the control circuit. This feedback allows the system to adjust the switching frequency and duty cycle dynamically, preventing localization effects that cause noise while maintaining optimal power conversion efficiency under varying load conditions.
3Device complexity
If the DC-DC converter uses fixed switching frequency, then circuit design is simplified, but at light loads the switching operation localizes causing output voltage ripple
Solution Approach 1:
The patent achieves universality by designing a control circuit that can operate in multiple modes (PWM and PFM) using the same basic oscillation and skipping circuits. This multi-functionality allows the system to maintain relatively simple circuit design while avoiding output voltage ripple through adaptive frequency control that prevents switching localization.
Data Source
AI summary
A DC-DC converter prevents localization of switching operations at light loads and is able to improve power conversion efficiency. The DC-DC converter of some variations performs pulse frequency modulation control at light loads, and includes a reducing circuit configured to skip an oscillation frequency signal at light loads and to generate a skipped signal.