EMI Shunt Filter Circuit for DC/DC Converter Common-Mode Noise
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Solution Overview
Problem
Existing electrical power systems in aircraft, particularly those using hybrid-electric propulsion, face challenges in reducing common mode emissions from DC/DC converters, which can introduce voltage stresses and parasitic currents.
Innovation Solution
The implementation of a power system architecture that includes a multi-level DC/DC converter electrically coupled with a battery, and an EMI filter network with EMI shunt filters, which are first or second order filters, to shunt common mode electric current to less-resistive paths, limit voltage, and reduce common mode voltage noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional EMI filtering methods using common mode inductors and split DC link configurations are used, then common mode emissions are reduced, but system weight increases and device complexity increases
Solution Approach 1:
The patent extracts and eliminates the heavy common mode inductors and split DC link configurations from the system while maintaining EMI filtering functionality through alternative circuit topologies and control methods
Solution Approach 2:
The patent changes the operating parameters and circuit configuration by using phase-shifted full-bridge rectifiers and modified switching sequences to achieve common mode noise cancellation without requiring additional heavy filtering components
2Object-affected harmful factors
If traditional EMI filtering methods using common mode inductors and split DC link configurations are used, then common mode emissions are reduced, but device complexity increases
Solution Approach 1:
The patent makes the DC/DC converter circuit perform multiple functions simultaneously - power conversion, EMI filtering, and common mode noise cancellation - through integrated control strategies rather than separate dedicated components
Solution Approach 2:
The patent achieves EMI reduction by modifying switching phase angles and duty cycles in the full-bridge rectifier circuit, using parameter optimization rather than additional complex filtering hardware
3Power
If DC/DC converters are used to regulate voltage in hybrid-electric propulsion systems, then power regulation is achieved, but common mode voltage stresses and parasitic currents are introduced
Solution Approach 1:
The patent converts the harmful common mode voltage stresses and parasitic currents generated by the DC/DC converter into beneficial effects by using phase-shifted switching to cancel these emissions through controlled interference
Solution Approach 2:
The patent employs control strategies that monitor and adjust switching phase angles and duty cycles to actively cancel common mode emissions, creating a feedback mechanism that reduces harmful effects while maintaining power regulation
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
This solution effectively reduces common mode voltage/current noise in the power system, eliminates the need for heavy common mode inductors and split DC link configurations, and provides weight performance benefits while containing common mode noise without introducing significant current stresses.
Implementation Method 1
EMI shunt filters, which are first or second order filters, to shunt common mode electric current to less-resistive paths
Data Source
AI summary
A power system is provided. The power system includes a multi-level DC/DC converter electrically coupled with a terminal of a voltage source, such as a battery. The power system includes an EMI filter network having EMI shunt filters electrically coupled between the terminals of the battery and a reference frame or grounding system. The EMI shunt filters each include at least one of a first order filter and a second order filter. The elements of these ordered filters can be used to shunt common mode electric current to less-resistive paths, limit voltage, and reduce common mode voltage noise to ultimately reduce the common mode effects in the power system.