Externally Excited Synchronous Machine With Contactless Rotor Current Feedback
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Solution Overview
Problem
Existing externally excited electric synchronous machines face challenges in maintaining operational stability and flexibility due to difficulties in adjusting operating parameters, particularly the current flowing through the rotor coil, which limits their variability and adaptability.
Innovation Solution
Incorporating a signal coil connected in series with the rotor coil to generate a magnetic field detected by a sensor, allowing for contactless transmission of operating signals to the stator, enabling real-time adjustment of the rotor field based on load current, thereby enhancing stability and variability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotor coil is supplied with DC voltage inductively, then the rotor field is generated, but the current flowing through the rotor coil cannot be easily monitored or adjusted
Solution Approach 1:
The rotor circuit is segmented into two separate coils: the rotor coil for generating the magnetic field and the signal coil for transmitting operating signals. This segmentation allows independent optimization of each coil's function, enabling current monitoring and adjustment without interfering with the primary field generation process.
Solution Approach 2:
The signal coil acts as an intermediary element that transmits information about the rotor coil current to the stator side through magnetic coupling. This intermediary mechanism enables indirect monitoring and control of the rotor current without requiring direct electrical connections, thus maintaining operational stability while improving adjustability.
2Reliability
If the matching between stator and rotor is fixed, then the desired operation is achieved, but changes in operating parameters are difficult to realise
Solution Approach 1:
The system transitions from a fixed matching configuration to a dynamic one where operating parameters can be adjusted in real-time. The signal transmission device enables continuous monitoring of rotor coil current, allowing the control system to dynamically adapt the stator- rotor interaction to changing operational requirements while maintaining stability.
Solution Approach 2:
The signal coil provides feedback information about the rotor coil current to the stator side, enabling closed-loop control. This feedback mechanism allows the system to automatically adjust operating parameters to maintain desired performance while adapting to changing conditions, thus achieving both stability and variability.
3Ease of operation
If a signal coil is added in series with the rotor coil, then contactless transmission of operating signals is enabled, but the device complexity increases
Solution Approach 1:
The signal coil serves multiple functions: it transmits operating signals from the rotor to the stator, enables current monitoring, and provides feedback for control purposes. This multi-functionality justifies the additional component by consolidating several capabilities into a single element, thereby limiting the increase in overall device complexity.
Solution Approach 2:
The patent replaces mechanical or direct electrical connection methods for signal transmission with a magnetic field-based inductive coupling system. This substitution eliminates the need for sliding contacts or complex wiring arrangements, reducing mechanical complexity while enabling contactless signal transmission and monitoring.
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 solution allows for simple and effective monitoring and adjustment of the synchronous machine's operating parameters, resulting in increased operational stability and variability, facilitating easier implementation of changes during operation.
Implementation Method 1
the signal coil connected in series with the machine rotor coil and on the machine stator a magnetic field sensor. The magnetic field sensor detects the magnetic field generated by the signal coil during the operation
Implementation Method 2
the machine rotor coil generates a magnetic field during the operation, which in the following is also referred to as rotor field. For this purpose, the machine rotor coil is supplied with a DC voltage during the operation
Implementation Method 3
The machine stator comprises a coil that is fixed to the machine stator, which in the following is also referred to as machine stator coil. The machine stator coil generates a magnetic field during the operation, which in the following is also referred to as stator field
Data Source
AI summary
An externally excited electric synchronous machine may include a machine rotor, a machine stator, and a signal transmission device for contactless transmission of an operating signal corresponding to a DC voltage to the machine stator. The machine rotor may include a rotor shaft and a machine rotor coil. The machine rotor coil may be supplied with DC voltage and may provide a magnetic rotor field. The machine stator may include a machine stator coil that is fixed relative to the machine stator. The machine stator coil may provide a magnetic stator field, which may interact with the magnetic rotor field such that the machine rotor rotates. The signal transmission device may include (i) on the machine rotor, a signal coil connected in series with the machine rotor coil and (ii) on the machine stator, a magnetic field sensor that detects a magnetic field provided via the signal coil.