Compressor Noise Cancellation via Phase Synchronization
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Solution Overview
Problem
Screw compressors in heating and cooling systems produce significant noise due to pressure pulsations, leading to the need for large and costly muffler systems to attenuate these sounds, which can be complex and expensive.
Innovation Solution
A control circuit system that synchronizes the rotational speed and phase of multiple compressors using phase-lock loop circuits, adjusting the phase and frequency of pressure pulse waveforms to create a composite pressure pulse with higher frequency and lower peak-to-peak amplitude, thereby reducing noise without the need for error or acoustic sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If dissipative or absorptive muffler systems are used to attenuate sound from screw compressors, then noise attenuation is achieved, but the system becomes expensive and large in size
Solution Approach 1:
The invention changes the operating parameters of the compressors by varying rotational speed continuously. This allows modification of the pressure pulse frequency and amplitude characteristics, transforming the acoustic parameters of the noise source itself rather than treating it downstream with passive mufflers.
Solution Approach 2:
The system transitions from fixed-speed operation to dynamically adjustable variable speed operation. By continuously varying the compressor speed, the system can optimize the pressure pulse characteristics in real-time, reducing noise at the source without requiring large passive attenuation devices.
2Object-affected harmful factors
If low frequency sound with high peak-to-peak amplitude is attenuated, then noise reduction is achieved, but the muffler system size and cost increase significantly
Solution Approach 1:
The invention changes the frequency and amplitude parameters of the pressure pulses by varying compressor speed. By increasing frequency and reducing peak-to-peak amplitude through speed modulation, the acoustic characteristics are transformed to require smaller attenuation volume.
Solution Approach 2:
The invention converts the harmful high-amplitude low-frequency pressure pulses into beneficial lower-amplitude higher-frequency pulses through variable speed operation. This transformation turns the noise problem into an opportunity for active noise control through parameter modulation.
Data Source
AI summary
A system for cancelling or attenuating noise in at least two positive displacement compressors proximately located from each other for use with a heating or cooling system. A lead compressor and a lag compressor have a controllable rotational speed and phase of operation. A controller selectably controls the rotational speed and the phase of operation of each of the compressors. The controller controls the rotational speed of the compressors at substantially the same speed for each compressor, with a phase-lock loop and a comparator circuit for each compressor. The controller controls the phase of operation of the compressors through an oscillator so that the lead and lag compressor pressure pulses are spaced between successive outlet pressure pulses to effectively double the combined pulsation frequency for noise attenuation.