Outer Rotor Air Compressor Voltage Control for Noise-Stable Discharge

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Solution Overview

Problem

Existing air compressors face challenges in increasing discharge amount without causing motor rotation instability and excessive noise, particularly when using outer rotor motors, as they generate more sound and have limited effectiveness in high-pressure regions.

Innovation Solution

The air compressor employs an outer rotor motor controlled by a controller that adjusts stator winding voltage based on rotor position information or induced current, separates current components for torque and magnetic flux, and uses vector control to stabilize rotation, incorporating neodymium magnets for increased torque and inertia.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the number of rotations is increased to improve compression efficiency and discharge amount, then productivity is improved, but generated sound increases

Engineering Contradiction:
Improvedischarge amountVSAvoidgenerated sound
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent applies dynamic control by using a controller to adjust the voltage applied to the stator winding based on rotor position information. This enables the motor to operate with optimized voltage at different rotation speeds and positions, improving compression efficiency and discharge amount while suppressing harmonic noise generation through adaptive voltage adjustment rather than simple speed increase

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the electrical parameters by controlling the voltage applied to the stator winding based on rotor position. This parameter change allows the motor to achieve better compression performance and discharge amount while reducing harmonic noise through position-dependent voltage optimization

Inventive Principle:
Principle #35Parameter changes

2Productivity

If cylinder diameter or stroke is increased to increase discharge amount, then productivity is improved, but device complexity and size increase

Engineering Contradiction:
Improvedischarge amountVSAvoidcylinder dimensions
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces mechanical solutions (increasing cylinder diameter or stroke) with an electrical control solution. By using a controller to adjust stator winding voltage based on rotor position, the system achieves increased discharge amount without modifying the mechanical dimensions of the cylinder, thus avoiding increased device complexity and size

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If high torque is generated in the motor to increase discharge amount, then productivity is improved, but current reaches upper limit and rotation stability decreases

Engineering Contradiction:
Improvedischarge amountVSAvoidmotor rotation stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The patent implements feedback control by using a controller that monitors rotor position information and adjusts the voltage applied to the stator winding accordingly. This feedback mechanism enables the motor to generate high torque when needed while maintaining rotation stability through continuous adjustment, preventing current from reaching upper limits and avoiding rotation instability

Inventive Principle:
Principle #23Feedback

4Power

If motor drive current is increased to generate high torque, then power is improved, but electromagnetic force increases and generated sound increases

Engineering Contradiction:
Improvemotor torqueVSAvoidgenerated sound
Core Design Contradiction:
PowerVSObject-generated harmful factors

Solution Approach 1:

The patent applies dynamic control by adjusting the voltage applied to the stator winding based on rotor position information. This enables the motor to generate high torque when needed while suppressing harmonic noise generation through position-dependent voltage optimization, avoiding the need to continuously increase drive current

Inventive Principle:
Principle #15Dynamics

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 configuration suppresses harmonic noise generation while enhancing discharge capacity and stabilizing motor rotation, even under varying loads, without the need for additional position sensors, thus maintaining efficiency and compact size.

Implementation Method 1

the controller is configured to adjust a voltage applied to a stator winding of the stator, based on induced current flowing through the stator winding

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

incorporating neodymium magnets for increased torque and inertia

Methodology Applied
Scientific EffectMagnetic field interaction: Magnetic Field

Data Source

PatentEP4306802B1Air compressor
Publication Date: 2025.07.30 MAX CO LTD
  • EP4306802B1 patent drawingFigure 1
  • EP4306802B1 patent drawingFigure 2
  • EP4306802B1 patent drawingFigure 3

AI summary

An air compressor (1) includes: a motor (20) configured to drive a compression mechanism (10) for compressing air, and a controller (30) configured to control the motor. The motor is an outer rotor motor including a stator (21) and a rotor (22) disposed on an outer side of the stator. The controller is configured to adjust a voltage applied to a stator winding (21a-c) of the stator, based on position information of the rotor.