Turbo Compressor Shaft Angle Detection with Runout Frequency Filtering

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Solution Overview

Problem

Existing drive systems for turbo compressors face challenges in accurately detecting the rotational angle of the shaft due to shaft runout components, particularly during disturbances such as surging, which affect the amplitude of the detection signal and hinder precise control.

Innovation Solution

A drive system that includes a shaft supported in a non-contact manner using electromagnetic forces, with a rotational angle detector outputting a signal superimposable with a specific frequency component, and a signal processing unit that reduces this frequency component to enhance detection accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a rotational angle detector is used to detect the rotational angle of the shaft, then the rotational angle information is obtained, but the detection accuracy is degraded due to shaft runout components superimposed on the detection signal

Engineering Contradiction:

Improverotational angle detection accuracyVSAvoidshaft runout interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The signal processing unit extracts and removes the shaft runout frequency component from the detection signal. By identifying the specific frequency range corresponding to shaft runout and selectively eliminating it, the system separates the harmful interference from the useful rotational angle information, thereby improving detection accuracy without affecting the shaft's mechanical operation

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system continuously monitors the detection signal, identifies shaft runout components through frequency analysis, and dynamically adjusts the signal processing to remove these components. This closed-loop approach ensures that the rotational angle detection remains accurate even when shaft runout conditions vary during operation

Inventive Principle:

Principle #23Feedback

2Ease of operation

If the shaft is supported in a non-contact manner using electromagnetic forces, then mechanical friction is eliminated, but shaft runout occurs due to electromagnetic force fluctuations during disturbances such as surging

Engineering Contradiction:

Improvefrictionless supportVSAvoidshaft position stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The system converts the harmful effect of electromagnetic force fluctuations into a detectable signal characteristic. By recognizing that shaft runout caused by electromagnetic disturbances produces specific frequency components in the detection signal, the system can identify and remove these components, thereby maintaining accurate rotational angle detection despite the inherent instability of non-contact support during disturbances

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Measurement precision

If signal processing is performed to reduce shaft runout frequency components, then detection accuracy is improved, but system complexity increases due to additional processing requirements

Engineering Contradiction:

Improverotational angle detection accuracyVSAvoidsignal processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The signal processing unit changes the frequency domain parameters of the detection signal by filtering out specific frequency ranges corresponding to shaft runout. This parameter transformation approach converts the complex problem of removing varying amplitude shaft runout components into a simpler frequency-based filtering operation, achieving high detection accuracy with relatively straightforward processing

Inventive Principle:

Principle #35Parameter changes

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 detects the rotational angle of the shaft by reducing specific frequency components, enabling precise control and minimizing the impact of shaft runout, thus improving operational stability and efficiency.

Implementation Method 1

a support configured to support the shaft in a non-contact manner using an electromagnetic force

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

a driver configured to rotationally drive the shaft using an electromagnetic force

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Data Source

PatentUS20260025041A1Drive system, turbo compressor, and refrigeration device

Publication Date: 2026.01.22 DAIKIN INDUSTRIES LTD

AI summary

A drive system includes a shaft, a support, a driver, a rotational angle sensor, a signal processing unit, and a controller. The rotation angle sensor outputs a first signal on which a specific frequency component is superimposable. The signal processing unit generates, based on the first signal, a second signal by performing a reduction process in order to reduce the specific frequency component included in the first signal. The controller controls the support and the driver. The controller detects the rotational angle of the shaft based on the second signal. A frequency of the specific frequency component reduced by the reduction process is lower than a frequency of a first frequency component included in the first signal. The first frequency component is an alternating-current frequency component other than a direct-current component and corresponds to the change in the rotational angle of the shaft.