Self-Powered Active EMI Filter Using Thermoelectric Modules
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Solution Overview
Problem
Conventional active EMI filters for PWM inverters require external power supplies, introducing noise and grounding paths, and only effectively reduce common mode noise on one side, leading to increased noise on the other side, while passive filters are heavy and costly.
Innovation Solution
A self-powered active EMI filter using thermoelectric modules to generate power for operational amplifiers and regulators, eliminating the need for external power supplies and providing floating filtering capabilities to reduce common mode noise on both AC and DC sides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive filters are used to filter common mode noise, then filtering capability is improved, but weight and size increase considerably
Solution Approach 1:
The patent replaces the mechanical/passive filtering system (inductors and capacitors) with an active electronic filtering system using operational amplifiers. This substitution eliminates the need for heavy passive components while maintaining filtering capability through active circuitry that generates counter-phase signals to cancel common mode noise.
Solution Approach 2:
The patent changes the operating parameters by using active components (operational amplifiers) that can dynamically adjust their operation based on the noise conditions. The operational amplifiers operate in inverting and non-inverting modes to generate signals with specific phase relationships, changing the fundamental operating mode from passive to active filtering.
2Weight of moving object
If active EMI filter with external power supply is used, then weight is reduced and power density is improved, but noise signals are introduced through additional electrical loops
Solution Approach 1:
The active EMI filter is designed to be self-powered by utilizing the existing electrical loops and power availability within the PWM inverter system. The filter draws power from the same electrical pathways that carry the signal, eliminating the need for separate external power supplies and their associated noise-introducing electrical loops.
Solution Approach 2:
The electrical loops in the PWM inverter system serve dual purposes: they carry both the power signal and provide the power source for the active EMI filter. This multi-functionality eliminates the need for dedicated power supply loops, reducing the number of electrical pathways and potential noise sources.
3Weight of moving object
If active EMI filter with external power supply is used, then weight is reduced, but grounding path is required which allows signal leakage
Solution Approach 1:
The filter uses the existing signal-carrying electrical loops to power itself, eliminating the need for separate grounding paths. By drawing power from the live signal pathways, the system maintains electrical isolation and prevents signal leakage through grounding connections.
Solution Approach 2:
The grounding path requirement is extracted and eliminated from the system design. The patent removes the need for separate grounding connections by using the existing insulated electrical loops for both power and signal transmission, thereby preventing signal leakage through ground paths.
4Reliability
If active EMI filter is used on one side of PWM inverter, then common mode noise is reduced on that side, but noise increases considerably on the other side
Solution Approach 1:
The active EMI filter is designed to handle both the AC side and DC side common mode noise simultaneously through its dual operational amplifier configuration. The filter processes signals from both sides of the PWM inverter, providing comprehensive noise reduction across the entire system rather than just one side.
Solution Approach 2:
The patent merges the filtering functions for both AC and DC sides into a single integrated active EMI filter unit. By combining the filtering operations and using shared power pathways, the system achieves coordinated noise reduction on both sides without the trade-offs of separate filtering systems.
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 self-powered active EMI filter effectively reduces common mode noise on both sides of the PWM inverter, improving filtering performance and eliminating the need for additional power sources, resulting in a compact and lightweight solution.
Implementation Method 1
at least one thermoelectric module, where each thermoelectric module comprises a conducting layer; and where the direct current link and at least one of the at least two operational amplifiers are operatively coupled to the at least one thermoelectric module
Data Source
AI summary
A filtering unit is presented. The filtering unit includes at least two operational amplifiers, where each of the at least two operational amplifiers includes an input end and an output end, where the input end of one operational amplifier is coupled across the corresponding input end of another operational amplifier of the at least two operational amplifiers. The filtering unit also includes a direct current link operatively coupled to the at least two operational amplifiers and at least one thermoelectric module, where each thermoelectric module includes a conducting layer, where the direct current link and at least one of the at least two operational amplifiers are operatively coupled to the at least one thermoelectric module. A filtering system is also presented.