Inductive Rotary Joint Air-Gap Fluctuation Control
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Solution Overview
Problem
In non-contacting inductive rotary joints, the fluctuation in air-gap between rotatable units leads to significant variations in stray inductance, requiring feedback from output side sensors to maintain constant electrical parameters, which is impractical due to mechanical constraints and increased complexity with larger units.
Innovation Solution
An inductive rotary joint design that includes a power generator, an inductive power transmitter, a measurement means to determine electrical parameters, and a functional unit with a model simulating the transmission function to control the power generator, eliminating the need for feedback from output side sensors by maintaining electrical parameters constant on the load side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inductive rotary joints are used for non-contact power transmission, then torque and wear are minimized, but stray inductance increases due to air-gap fluctuations
Solution Approach 1:
The patent implements a feedback control system where sensors on the output side continuously monitor electrical parameters (voltage, current, power) and transmit this information back to the input side. A control amplifier adjusts the input parameters dynamically to compensate for stray inductance variations caused by air-gap fluctuations, thereby maintaining stable output parameters despite the harmful inductance effects
Solution Approach 2:
The system dynamically changes electrical parameters (voltage, current, frequency) on the input side based on detected output conditions and air-gap position. By adjusting these parameters in real-time, the system compensates for the variable stray inductance, transforming a static problematic parameter into a dynamically controlled variable
2Reliability
If output side sensors are added to regulate electrical parameters, then constant voltage supply is achieved, but device complexity increases
Solution Approach 1:
The patent introduces a closed-loop feedback system with sensors, signal transmitters, and control amplifiers that continuously monitor and adjust electrical parameters. This feedback mechanism enables automatic regulation of output voltage and current, compensating for load variations and air-gap fluctuations without manual intervention
Solution Approach 2:
The patent replaces mechanical slip-rings with an inductive coupling system, eliminating mechanical contact and associated wear. The added electronic control system substitutes for mechanical regulation mechanisms, using electromagnetic fields and electronic feedback instead of mechanical adjustments
3Object-generated harmful factors
If inductive coupling is used instead of slip-rings, then no carbon dust pollution occurs, but coupling factor fluctuates with relative positions
Solution Approach 1:
The system uses feedback from output side sensors to detect variations in coupling factor caused by relative position changes. This information is transmitted back and used to adjust input parameters, compensating for the fluctuating coupling and maintaining stable power transmission despite positional variations
Solution Approach 2:
The system dynamically adjusts electrical parameters (voltage, current, frequency) on the input side in response to detected coupling factor changes. By changing these parameters in real-time, the system compensates for the variable magnetic coupling, maintaining consistent power transfer efficiency across different rotational positions
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 design ensures stable electrical parameter transmission without the need for output side sensors, reducing mechanical complexity and maintaining constant voltage, current, or phase angle across varying load conditions, particularly beneficial for large units like computer tomographs.
Implementation Method 1
inductive power transmitter having a primary side and a secondary side, in which the primary side is fed by the power generator and the secondary side serves to feed a load
Implementation Method 2
a measurement means for determining at least one electrical parameter such as a voltage, a current, a phase angle of electrical energy fed by the power generator into the primary side of the power transmitter
Implementation Method 3
a functional unit for controlling the power generator with the aid of the at least one electrical parameter so that at least one other electrical parameter on the load, such as a voltage, a current, a phase angle, is maintained approximately constant
Data Source
AI summary
An inductive rotary joint for non-contact transmission of electrical energy between a stationary part and a rotating part of the rotary joint comprises a power generator for generating an alternating voltage or an alternating current, which feeds a load by means of a rotatable power transmitter. An electrical parameter on the primary side of the power transmitter is determined with a measurement means, and from this, the condition of another electrical parameter at the load is approximated by means of a functional unit. Regulation of the power generator is effected with this approximated value.