Rotary Transformer With Integrated PCB Position Sensing
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Solution Overview
Problem
Traditional wound rotor synchronous machines (WRSMs) face challenges due to brushes and slip rings causing friction, wear, and frequent maintenance, while polyphase rotary transformers offer a solution by eliminating these components, but there is a need for a compact and efficient design with integrated sensors for monitoring rotating members.
Innovation Solution
Integration of an inductive position sensor within a rotary transformer, utilizing a PCB on the rotating side as a target, with coils and targets positioned on both stationary and rotating sides to monitor rotor position efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional wound rotor synchronous machines use brushes and slip rings for power transfer, then power transfer between stator and rotor is achieved, but friction, wear, and frequent maintenance occur
Solution Approach 1:
The patent replaces the mechanical brush and slip ring system with a rotary transformer that uses electromagnetic induction for power transfer. The primary coil on the stator side and secondary coil on the rotor side enable wireless power transfer across the air gap, eliminating mechanical contact and its associated friction and wear.
Solution Approach 2:
The rotary transformer acts as an intermediary device between the stator and rotor, enabling power transfer through electromagnetic fields in the air gap without direct mechanical contact. This intermediary system resolves the conflict between power transfer capability and mechanical wear.
2Adaptability or versatility
If separate rotary transformer and position sensor systems are used, then power transfer and position monitoring functions are achieved, but device complexity and space requirements increase
Solution Approach 1:
The patent combines the rotary transformer and inductive position sensor into a single integrated assembly. The primary coil serves dual purposes: power transfer and position sensing. The sensor coils are positioned adjacent to the primary coil, sharing the same magnetic circuit and air gap, thereby reducing component count and simplifying the overall system.
Solution Approach 2:
The primary coil assembly serves multiple functions: it acts as both the power transfer coil for the rotary transformer and the excitation coil for the inductive position sensor. This multi-functionality reduces the number of separate components needed and simplifies the system architecture.
3Ease of manufacture
If compact integrated design is implemented, then space efficiency and manufacturing cost are improved, but manufacturing precision requirements increase
Solution Approach 1:
The integrated assembly is divided into distinct functional zones: the primary coil region for power transfer, the sensor coils positioned adjacent to it for position sensing, and the targets on the rotor. This segmentation allows for standardized manufacturing of modular components that can be assembled with controlled precision requirements.
Solution Approach 2:
The patent uses PCB technology to define coil positions and dimensions through standardized trace widths, spacing, and layouts. By transitioning from custom-wound coils to PCB-based coil structures, the manufacturing precision requirements are standardized and reduced, making the integrated design more manufacturable while maintaining functional performance.
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 integrated rotary position sensor provides a compact and efficient solution for monitoring rotating members, reducing manufacturing costs and improving efficiency in applications like electric vehicles.
Implementation Method 1
The rotary transformer may be used to feed the rotor of a wound rotor synchronous machine (WRSM)
Implementation Method 2
Integration of an inductive position sensor within a rotary transformer, utilizing a PCB on the rotating side as a target
Data Source
AI summary
A rotary transformer with an integrated inductive position sensor is disclosed herein. The rotary transformer comprises a stationary side and a rotating side. The stationary side includes a core defining a central axis and a first printed circuit board (PCB) coupled to the core. A primary coil of the rotary transformer is positioned within the core concentric with the central axis. An excitation coil of an inductive position sensor and at least one sensing coil of the inductive position sensor is positioned on the first PCB. The rotating side includes a second PCB with a secondary coil of the rotary transformer positioned on the second PCB. Additionally, at least one target for the inductive position sensor positioned on the second PCB. The rotary transformer may be advantageously used to feed the rotor of a wound rotor synchronous machine.