Train Power Converter Switching Frequency for Cabin Noise Control
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Solution Overview
Problem
The electrical power supply system in train cars generates significant noise and vibration due to the interaction between PWM harmonics and mechanical resonances, creating an unpleasant environment in passenger and staff compartments.
Innovation Solution
A system comprising sensors for measuring acoustic pressure and output data from the electrical power supply system, processed by a controller to adjust the operation point of the system, specifically the switching frequency of converters, to reduce noise and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If passive noise reduction solutions are used, then noise filtering is simple, but there is lack of space and materials for efficient passive solutions
Solution Approach 1:
The patent replaces passive mechanical noise filtering solutions with an active control system using speakers and microphones. Instead of using physical barriers or absorptive materials that would consume valuable space, the system uses acoustic waves generated by speakers to counteract noise measured by microphones, thereby solving the space constraint problem while maintaining noise reduction effectiveness
Solution Approach 2:
The system dynamically adjusts acoustic parameters (frequency, amplitude, phase) of the anti-noise sound waves based on real-time measurements. By changing these parameters adaptively, the system achieves effective noise cancellation without requiring fixed physical structures or materials that would occupy space
2Productivity
If switching frequency is increased to improve power conversion, then power supply efficiency is improved, but noise and vibration increase due to PWM harmonics
Solution Approach 1:
The patent converts the harmful PWM switching noise and vibrations into useful information for control. By measuring the noise characteristics and using them to generate counteracting sound waves, the system transforms the harmful acoustic emissions into a basis for active noise cancellation, allowing high switching frequencies to be used without compromising passenger comfort
Solution Approach 2:
The system dynamically adjusts the noise control parameters based on real-time measurements of PWM harmonics and structural vibrations. The active noise control system adapts its response to changing operating conditions, allowing the power conversion system to operate at optimal efficiency while maintaining acceptable noise levels through continuous adjustment
3Manufacturing precision
If accurate noise prediction is attempted, then design optimization is possible, but many physics and manufacturing uncertainties need to be mapped and quantified
Solution Approach 1:
The patent implements a self-adjusting noise control system that automatically adapts to actual noise conditions without requiring complex pre-characterization of all uncertainty sources. The system uses real-time measurements from microphones and sensors to determine the actual noise environment and adjusts its control parameters accordingly, eliminating the need for exhaustive uncertainty mapping during design
Solution Approach 2:
The system employs feedback control where microphones continuously monitor the acoustic environment and the controller adjusts the anti-noise signal accordingly. This closed-loop approach allows the system to compensate for manufacturing variations and physical uncertainties automatically, achieving accurate noise control without requiring precise prior knowledge of all uncertainty sources
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 system effectively reduces acoustic pressure in the train car's inner space by actively controlling the switching frequency of converters, thereby mitigating noise and vibration sources.
Implementation Method 1
The root cause is an unfavorable interaction between multiple core mechanical resonances in the kHz range and the clusters of PWM harmonics in the same frequency domains
Implementation Method 2
at least one second sensor, preferably provided on or close to at least one reactor corresponding to a train converter of the train car
Implementation Method 3
at least one first sensor and/or at least one second sensor for measuring data related to acoustic pressure in an inner space of the train car
Data Source
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AI summary
A system for operation of an electrical power supply system of a train car, comprising: at least one first sensor and/or at least one second sensor for measuring data related to acoustic pressure in an inner space of the train car; at least one third sensor for measuring data related an output of the electrical power supply system; a processor configured to: process the measured data from one or more of the at least one first sensor, from the at least one second sensor, and from the at last one third sensor, and adjust an operation point of the electrical power supply system based on the processed measured data so as to reduce the acoustic pressure in the inner space of the train car.