Variable- and Fixed-Frequency Compressor Control for Air Delivery

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Solution Overview

Problem

Traditional air compressors are high in energy consumption, low in efficiency, and limited in the adjustment range of output gas volume due to the connection of each compression unit to a corresponding oil-gas separator.

Innovation Solution

A method for controlling a compressor that adjusts free air delivery by dynamically controlling the working modes of variable-frequency and fixed-frequency compression units based on discharge pressure, using a combination of stopping, loading, and unloading modes, and incorporating an oil-gas separator to separate and cool the compressed gas and oil.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If each compression unit is connected to a corresponding oil-gas separator in a traditional drive system, then the system structure is simple and reliable, but the energy consumption is high and the efficiency is low

Engineering Contradiction:
Improveenergy consumptionVSAvoidsystem structure
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent merges multiple compression units (variable-frequency and fixed-frequency compression units) to share a common oil-gas separator. This consolidation reduces the number of separate separators needed, simplifying the overall system structure while enabling more efficient compression coordination that lowers energy consumption and improves overall system efficiency

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces variable-frequency compression units that can dynamically adjust their operating speed and load based on actual demand. This dynamic control allows the system to optimize energy consumption by matching compression output to required free air delivery, while the coordinated operation with fixed-frequency units maintains system reliability

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If a traditional single motor drive system is used, then the system structure is simple, but the adjustment range of output gas volume is limited

Engineering Contradiction:
Improveadjustment range of output gas volumeVSAvoiddrive system structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the compression system into multiple independent compression units with different frequency characteristics (variable-frequency and fixed-frequency). Each unit can operate independently or in coordination, allowing flexible adjustment of total output gas volume by controlling which units are active and at what load levels, thereby expanding the adjustable range while maintaining manageable system complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent designs the compression system so that multiple compression units can serve multiple functions - they can operate individually to provide different output levels, or work together to provide full capacity. The shared oil-gas separator also serves multiple units, making the system more versatile in handling various output requirements without proportionally increasing complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 method enhances flexibility and expands the adjustment range of free air delivery, resulting in energy savings and improved efficiency.

Implementation Method 1

a variable-frequency compression unit and a fixed-frequency compression unit which are respectively connected to an oil-gas separator, so that compressed gas is supplied to the oil-gas separator via the variable-frequency compression unit and the fixed-frequency compression unit in cooperation

Methodology Applied
Scientific EffectGas compression: Compression

Implementation Method 2

an oil-gas separator, arranged in the box body and configured to separate the oil-gas mixture

Methodology Applied
Scientific EffectOil-gas separation: Centrifugal Separation

Data Source

PatentEP4617492A1Compressor control method and compression system
Publication Date: 2025.09.17 PAN ASIA GAS TECH (WUXI) CO LTD
  • EP4617492A1 patent drawingFigure 1
  • EP4617492A1 patent drawingFigure 2~3
  • EP4617492A1 patent drawingFigure 4~5

AI summary

The present invention provides a method for controlling a compressor and a compression system, the method for controlling a compressor comprises: acquiring a discharge pressure of the compressor; and dynamically controlling working modes of the variable-frequency compression unit and the fixed-frequency compression unit according to the discharge pressure, so as to adjust free air delivery of the compressor, wherein the working modes at least include a stopping working mode, a loading working mode and an unloading working mode, and the variable-frequency compression unit and the fixed-frequency compression unit are respectively connected to an oil-gas separator, so that compressed gas is supplied to the oil-gas separator via the variable-frequency compression unit and the fixed-frequency compression unit in cooperation. According to the above method, the free air delivery of the compressor is adjusted by controlling the working modes of the variable-frequency compression unit and the fixed-frequency compression unit, so that the adjustment method for the free air delivery is more flexible, and the adjustment range of the free air delivery can be expanded.