Frequency Modulation Device for Switching Power Supply EMC
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Solution Overview
Problem
Switching power supply systems with fixed-frequency oscillators exhibit low Electromagnetic Compatibility (EMC) performance, leading to interference issues.
Innovation Solution
A frequency modulation device and method that includes a waveform generation unit, a frequency modulation unit for voltage-current conversion and arithmetic processing, and an RC oscillation unit to generate a frequency oscillation signal, effectively modulating the clock signal of the switching power supply, thereby improving EMC performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed-frequency oscillator is used in the switching power supply, then the circuit structure is simple, but the EMC performance is poor due to electromagnetic interference
Solution Approach 1:
The patent applies frequency modulation by dynamically varying the oscillation frequency around a center frequency. The oscillator output frequency is modulated according to a modulation signal, transforming the fixed-frequency system into a dynamic frequency system. This resolves the contradiction by maintaining circuit simplicity while reducing electromagnetic interference through frequency variation.
Solution Approach 2:
The patent changes the frequency parameter of the oscillator by introducing frequency modulation. The oscillation frequency is varied within a range around the center frequency based on the modulation signal, which disperses the electromagnetic energy spectrum and reduces peak interference levels while maintaining the basic circuit structure.
2Object-affected harmful factors
If frequency modulation is implemented to improve EMC performance, then electromagnetic interference is reduced, but the device complexity increases
Solution Approach 1:
The patent introduces a frequency modulation unit as an intermediary component between the oscillator and the rest of the power supply circuit. This unit generates the modulation signal and applies it to the oscillator, enabling frequency variation without fundamentally redesigning the entire power supply circuit, thus limiting the increase in device complexity.
Solution Approach 2:
The frequency modulation is implemented through periodic variation of the oscillation frequency around the center frequency. This periodic action disperses the electromagnetic interference energy across multiple frequency points in the spectrum, reducing peak interference levels while using a relatively simple modulation scheme.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances EMC performance, reliability, and safety by allowing the switching frequency to vary within a range, reducing electromagnetic interference and improving the overall performance of the switching power supply.
Implementation Method 1
an RC oscillation unit configured to perform RC oscillation processing based on the frequency modulation current to obtain a frequency oscillation signal as the clock signal of the switching power supply to be controlled
Data Source
AI summary
The present disclosure relates to a frequency modulation device, a switching power supply and a frequency modulation method thereof. The device includes: a waveform generation unit (10) configured to generate a periodic signal required for performing frequency modulation on a clock signal of a switching power supply to be controlled; a frequency modulation unit (20) configured to perform voltage-current conversion and arithmetic processing based on the periodic signal to obtain a frequency modulation current required for performing the frequency modulation on the clock signal of the switching power supply to be controlled; and an RC oscillation unit (30) configured to perform RC oscillation processing based on the frequency modulation current to obtain a frequency oscillation signal as the clock signal of the switching power supply to be controlled.