Hollow Rotor Shaft Rectifier Layout for Lower Centrifugal Load
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Solution Overview
Problem
In externally excited synchronous machines, the rotating rectifier experiences high centrifugal forces due to its placement on the rotor shaft, leading to potential damage and limiting the use of electronic components, and the temperature constraints of common materials result in reduced power output and increased costs.
Innovation Solution
The rectifier is positioned within the rotor shaft's cavity, allowing for a compact design that reduces centrifugal forces and enables improved mechanical stability, cooling, and efficient assembly, with options for prefabricated assemblies and thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the rectifier is arranged on the rotor shaft at a larger diameter, then the assembly space is increased, but the centrifugal forces acting on electronic components increase strongly, leading to potential damage
Solution Approach 1:
The rectifier is nested within the hollow rotor shaft, placing electronic components inside the shaft cavity rather than on the outer surface. This nesting approach allows the rectifier to be positioned at a smaller effective radius from the rotation axis, significantly reducing centrifugal forces while still providing adequate assembly space within the shaft's internal volume.
2Reliability
If the upper temperature limit of the rotor is reduced to match the temperature limit of electronic components, then the reliability of electronic components is improved, but the continuous and peak power of the motor has to be reduced
Solution Approach 1:
The rectifier is extracted from the conventional position on the rotor shaft surface and relocated to the interior of the hollow rotor shaft. This spatial extraction creates physical separation between heat-generating rotor windings and temperature-sensitive electronic components, allowing the rotor to operate at higher temperatures without compromising component reliability, thus maintaining motor power output.
3Device complexity
If the rectifier is arranged on the rotor shaft, then the electrical connection to rotor windings is simplified, but the mechanical stability of electronic components deteriorates due to high centrifugal forces
Solution Approach 1:
The rectifier is nested within the hollow rotor shaft, which provides a protective structural environment for electronic components. This nesting maintains simple electrical connections to rotor windings through the shaft structure while the shaft itself acts as a protective cage that enhances mechanical stability by constraining components closer to the rotation axis where centrifugal forces are lower.
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 configuration enhances mechanical stability, allows for more compact construction, simplifies assembly, and improves cooling, enabling higher performance and cost-effective use of components within the synchronous machine.
Implementation Method 1
An alternating current is required for the inductive transmission according to the transformational principle. This alternating current has to be rectified subsequently in a rectifier, so that a direct current applies at the rotor
Implementation Method 2
In an inductive electrically excited synchronous machine, the energy for a rotor winding is transmitted from a stator to a rotor by means of an inductive transmitter (rotary transformer)
Implementation Method 3
The electronic components arranged on the printed circuit board of the rectifier experience high centrifugal forces during the operation, which increase strongly with increasing rotational speed of the rotor
Data Source
AI summary
A rotor for an externally excited synchronous machine, e.g., for use as a traction motor of a motor vehicle, is disclosed. The rotor includes rotor windings arranged on a rotor shaft having at least one cavity. A rectifier is electrically connected to the rotor windings. The rectifier is at least partly arranged in the cavity of the rotor shaft.