Switching Control with Multi-Carrier Phase Shifts for EMI Reduction
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Solution Overview
Problem
Conventional power conversion devices struggle to achieve sufficient electromagnetic noise reduction across various measurement conditions using multiple switching frequencies.
Innovation Solution
A switching control device that sets multiple carrier frequencies and phase differences between switching square waves to control the switching operation, reducing harmonic noise components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a noise filter having an anti-noise component such as a choke coil or a capacitor is used, then electromagnetic noise is reduced, but device size and cost increase
Solution Approach 1:
The patent changes the switching frequency parameter dynamically by using multiple carrier frequencies (first carrier frequency and second carrier frequency) instead of a fixed frequency. This parameter variation disperses the electromagnetic noise energy across different frequency bands, reducing peak noise levels without requiring additional filtering components, thereby avoiding increases in device size and cost.
Solution Approach 2:
The patent implements periodic switching between different carrier frequencies in a repeating pattern. This periodic frequency modulation creates a frequency changing pattern that systematically distributes noise energy over time and frequency, achieving noise reduction through temporal and spectral distribution rather than through physical filtering components.
2Object-affected harmful factors
If a noise filter having an anti-noise component such as a choke coil or a capacitor is used, then electromagnetic noise is reduced, but device cost increases
Solution Approach 1:
The patent changes the switching frequency parameter dynamically by using multiple carrier frequencies (first carrier frequency and second carrier frequency) instead of a fixed frequency. This parameter variation disperses the electromagnetic noise energy across different frequency bands, reducing peak noise levels without requiring additional filtering components, thereby avoiding increases in device size and cost.
Solution Approach 2:
The patent makes the power conversion device itself generate the noise reduction effect through its own switching control mechanism. By internally modulating the switching frequency between multiple carrier frequencies, the device creates frequency dispersion that reduces its own electromagnetic noise emissions, eliminating the need for separate external filtering components and associated costs.
3Object-affected harmful factors
If multiple switching frequencies are used, then electromagnetic noise is reduced, but sufficient noise reduction effect cannot be obtained under various measurement conditions
Solution Approach 1:
The patent employs multiple carrier frequencies (first carrier frequency and second carrier frequency) with different frequency values to create a frequency changing pattern. This multi-frequency approach disperses electromagnetic noise energy across broader spectral ranges, enhancing the effectiveness under various measurement conditions by ensuring that noise energy is not concentrated at any single frequency that might be emphasized by different measurement setups.
Solution Approach 2:
The patent implements periodic switching between different carrier frequencies in a repeating pattern. This periodic frequency modulation creates a frequency changing pattern that systematically distributes noise energy over time and frequency, achieving noise reduction that is more consistent across various measurement conditions by preventing concentration of noise energy at any particular frequency or time interval.
Data Source
AI summary
A switching control device is a device that controls a switching operation performed by a switching element, and includes: a frequency setting unit that sets at least a first carrier frequency and a second carrier frequency; a phase shift setting unit that sets a phase difference between a first switching square wave determined by the first carrier frequency set by the frequency setting unit and a second switching square wave determined by the second carrier frequency set by the frequency setting unit; and a control signal generation unit that controls the switching operation performed by the switching element on the basis of the phase difference set by the phase shift setting unit.