AMB Position Detection Using Square Wave Oscillator
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Solution Overview
Problem
Classical position detection devices for active magnetic bearings consume high power and are difficult to integrate, making them expensive and inefficient.
Innovation Solution
A position detection device using a programmable digital component to generate a 25 KHz square waveform signal, a current amplifier with a Darlington transistor and resistors for sensing inductance coils, and a differential amplifier to deliver position values via an A/D converter, reducing power consumption and enabling easier integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a sinusoidal oscillator with push-pull power transistor and tank capacitor is used for position detection, then position detection function is achieved, but power consumption is high and electronics integration is difficult
Solution Approach 1:
The patent replaces the classical sinusoidal oscillator with a square wave oscillator using a programmable digital component (microcontroller or DSP). This substitution eliminates the need for analog components like push-pull power transistors and tank capacitors, thereby reducing power consumption and enabling easier electronics integration while maintaining the position detection function through digital signal processing
Solution Approach 2:
The patent changes the waveform parameter from sinusoidal to square wave and operates at a lower frequency (25 KHz). This parameter change simplifies the oscillator circuit design, reduces power consumption, and allows direct digital synthesis using programmable components, thereby resolving the contradiction between achieving position detection and minimizing power consumption with improved integrability
2Measurement precision
If sinusoidal waveform is used for oscillator, then position detection is achieved, but power consumption increases significantly
Solution Approach 1:
The patent substitutes the sinusoidal oscillator with a digital square wave oscillator. The position detection accuracy is maintained through differential amplification of the voltages induced in the sensing coils and subsequent digital signal processing, while the square wave generation consumes significantly less power due to its simpler circuit implementation
Solution Approach 2:
The patent uses two sensing inductance coils that are identical copies of each other, connected in opposition. This differential configuration allows position detection through voltage difference measurement, maintaining measurement precision while enabling the use of low-power square wave excitation instead of high-power sinusoidal excitation
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 solution achieves reduced power consumption and integration benefits, allowing precise position detection of rotating shafts with improved efficiency and cost-effectiveness for active magnetic bearings.
Implementation Method 1
two sensing inductance coils (12A, 12B) in opposition and connected to a differential amplifier (22)
Data Source
AI summary
A position detection device of active magnetic bearings (AMB's) maintaining the position of a rotating shaft and comprising two sensing inductance coils, the position detection device comprising a programmable digital component for generating a 25 KHz square waveform signal, a current amplifier receiving the 25 KHz square waveform signal and injecting two identical control currents in the two sensing inductance coils, a differential amplifier for amplifying a voltage difference between the resulting voltages in the two sensing inductance coils and, depending on the displacement of the rotating shaft, an analog to digital (A/D) converter for delivering a position value from the voltage difference.