Common-Mode Power Supply Circuit With Resonance Suppression
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Solution Overview
Problem
Existing power supply devices with noise attenuation units using common mode choke coils can experience high gain at resonance frequencies, leading to oscillation and ineffective noise attenuation.
Innovation Solution
The power supply device incorporates a noise attenuation unit with an auxiliary coil, a capacitor, and a resonance suppression unit including an amplification unit and a low-pass filter. This configuration adjusts the insulation distance and parasitic capacitance to suppress oscillation and ensure effective noise attenuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a noise attenuation unit with amplification unit is used to attenuate noise, then noise attenuation performance is improved, but oscillation occurs at resonance frequency
Solution Approach 1:
A low-pass filter is introduced as an intermediary component between the amplification unit and the feedback path. This filter mediates the feedback signal by attenuating high-frequency components including resonance frequencies, thereby preventing oscillation while preserving the noise attenuation function at lower frequencies.
Solution Approach 2:
The frequency response characteristics of the feedback path are modified by introducing the low-pass filter. The filter changes the parameter of frequency selectivity, allowing passage of low-frequency noise attenuation signals while blocking high-frequency oscillation-prone signals, thus resolving the contradiction between noise attenuation and oscillation suppression.
2Object-affected harmful factors
If common mode choke coil is used in noise attenuation configuration, then noise attenuation is achieved, but high gain at resonance frequency causes oscillation
Solution Approach 1:
The low-pass filter acts as an intermediary that selectively attenuates the feedback signal at resonance frequencies. This prevents the high gain at resonance frequencies from causing oscillation, while maintaining the noise attenuation capability at non-resonance frequencies through the common mode choke coil configuration.
Solution Approach 2:
The resonance phenomenon, which initially causes harmful oscillation, is managed by the low-pass filter that converts the potentially harmful high-frequency resonance into a filtered signal. The filter transforms the oscillation-prone feedback into a controlled signal that maintains noise attenuation without triggering oscillation.
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 effectively suppresses oscillation in the closed circuit, allowing for reliable noise attenuation in the power supply device, even at resonance frequencies.
Implementation Method 1
a low-pass filter connected to the amplification unit and provided between the auxiliary coil and the capacitor
Implementation Method 2
a resonance suppression unit including an amplification unit and a low-pass filter connected to the amplification unit
Implementation Method 3
an auxiliary coil including a third winding and a third coating configured to coat the third winding and wound around the core
Implementation Method 4
a first common mode coil including a first winding and a first coating configured to coat the first winding and wound around the core, a second common mode coil including a second winding and a second coating configured to coat the second winding and wound around the core
Data Source
AI summary
In this power supply device, a main circuit includes a core, a first common mode coil, a second common mode coil, a first connection line, and a second connection line, and a noise attenuation unit includes an auxiliary coil having a third winding and a third coating, a capacitor connected to the first connection line, and a resonance suppression unit that includes an amplification unit and a low-pass filter connected to an output terminal of the amplification unit and that is provided between the auxiliary coil and the capacitor.