Compressor Magnetic Field Sensing for Contactless Speed Detection
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Solution Overview
Problem
Existing methods for determining the operating state of a compressor and the rotational speed of its drive are either invasive, require specialized personnel, or cannot distinguish between different operating states like standstill, idling, and load run.
Innovation Solution
A contactless method involving the detection of a magnetic field generated by the current in the power supply cable or motor lead, followed by analysis of the frequency spectrum to determine the operating state and rotational speed of the compressor drive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If potential-free contacts are tapped in the control cabinet to detect operating states, then the compressor can be monitored for standstill, idling, and load run states, but the installation requires electrically instructed personnel and the compressor must be disconnected from the electrical mains
Solution Approach 1:
The patent replaces electrical contact-based detection with magnetic field-based detection. Instead of tapping potential-free contacts in the control cabinet, the invention uses a detection element that senses the magnetic field generated by current in the power supply cable or motor lead, thereby determining operating state and rotational speed without electrical contact or disconnection
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the current-carrying conductor and the detection element. The detection element detects the magnetic field generated by the current, which serves as a non-invasive mediator to convey information about operating state and rotational speed without direct electrical contact
2Measurement precision
If reflex pulse counting with optical sensors is used to determine rotational speed, then the shaft speed can be measured, but the installation requires attaching reflective markers and solid mechanical attachment of the optical sensor, which is time-consuming and cannot distinguish between different operating states
Solution Approach 1:
The patent replaces mechanical attachment methods (reflective markers on the shaft and solid mechanical mounting of optical sensors) with a contactless magnetic field detection method. The detection element is attached to the power supply cable or motor lead, which remains stationary, eliminating the need for time-consuming mechanical installation on rotating or vibrating parts
Solution Approach 2:
The patent makes the detection element serve multiple functions: it simultaneously determines both the operating state (standstill, idling, load run) and the rotational speed of the compressor drive by analyzing the frequency spectrum of the detected magnetic field, whereas previous methods required separate systems for each measurement
3Ease of operation
If active current measurement is performed at the supply line via current clamp or Rogowski coil, then the magnetic field strength can be measured without electrical contact, but it requires opening the control cabinet and cannot determine rotational speed
Solution Approach 1:
The patent enhances the capability of contactless magnetic field detection by enabling it to perform both operating state determination and rotational speed measurement through frequency spectrum analysis, whereas previous current measurement methods could only determine operating state. The same detection element and measurement principle serve multiple purposes
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 method allows for a reliable, fast, and inexpensive determination of the compressor's operating state and rotational speed without the need for precise measurement of magnetic field strength or current RMS value, making it suitable for both installed and new compressors.
Implementation Method 1
detecting a magnetic field generated by a current of at least one phase of a power supply cable or at least one phase of a motor lead
Data Source
AI summary
The disclosure relates to a method for determination of an operating state of a compressor and/or a rotational speed of a compressor drive of the compressor comprising; measuring, over a time range, a magnetic field associated with one or more phases of an electrical power supply conductor supplying the compressor with electrical power; wherein the magnetic field is measured by a detection element to provide a representation of the magnetic field; determining a frequency spectrum of the representation of the magnetic field over the time range; and analyzing the frequency spectrum of the representation of the magnetic field over the time range to determine an operating state of the compressor and/or to determine a rotational speed of the compressor drive. The disclosure further relates to a device for carrying out the method, a compressor measuring system, and a computer-readable storage medium.