Resistor-Integrated Contact Ring for Electric Machine Shaft Voltage Dissipation
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Solution Overview
Problem
Electric machines experience shaft voltages due to various causes, leading to spark erosion in bearings and electromagnetic interference, which can damage the machine and disrupt nearby electrical devices.
Innovation Solution
An electrically insulating contact ring with an integrated resistor is mounted on the rotor shaft, providing a secure and reliable electrical connection to dissipate shaft voltages via a slip-ring group, effectively protecting the resistor from environmental influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sliding contact is used to dissipate shaft voltages, then charge carriers can be dissipated from the rotor shaft, but the arrangement becomes complex and requires additional components like capacitance and inductance
Solution Approach 1:
The invention extracts the essential function of shaft voltage dissipation from the complex arrangement of sliding contacts, capacitance, and inductance, and implements it through a simple ohmic resistor connected between the rotor shaft and excitation winding, eliminating unnecessary components
Solution Approach 2:
The invention uses a simple, inexpensive ohmic resistor instead of complex and expensive sliding contact arrangements with capacitance and inductance, achieving the same protective function with a basic electrical component
2Reliability
If an ohmic resistor is connected between excitation winding and rotor shaft, then shaft voltages are dissipated effectively, but the resistor is exposed to environmental influences
Solution Approach 1:
The resistor is nested within the hollow structure of the contact ring, which provides mechanical mounting on the rotor shaft and simultaneous environmental protection, integrating two functions into one component
Solution Approach 2:
The contact ring acts as a protective shell enclosing the resistor, isolating it from environmental influences while allowing electrical contact through designated contact surfaces
3Volume of moving object
If a contact ring with lateral contact surfaces is used, then space requirements are minimized, but the manufacturing precision requirements increase
Solution Approach 1:
The contact ring serves multiple functions simultaneously: mechanical mounting of the resistor, environmental protection, electrical contact with the rotor shaft, and electrical contact with the excitation winding, reducing the need for separate precision-aligned components
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 effectively dissipates shaft voltages, preventing damage to bearings and reducing electromagnetic interference, while ensuring a secure and space-efficient design.
Implementation Method 1
an electrical resistor which is electrically conductively connected to the rotor shaft and via which resistor charge carriers can be dissipated from the rotor shaft
Implementation Method 2
electrical resistor for dissipating shaft voltages occurring at the rotor shaft
Data Source
AI summary
An electric machine with at least one electrical resistor (24) for dissipating shaft voltages occurring at the rotor shaft (2) of a rotor (1), in which the electrical resistor (24) is enclosed in a contact ring (13) mounted on the rotor shaft (2) between contact surfaces (17, 23, 25, 28, 29) applied to the contact ring (13) on the outside, and in which the resistor (24) is electrically connected via the contact surfaces (17, 23, 25, 28, 29) to the rotor shaft (2) on one side and to the excitation winding (14) of the rotor (1) on the other side.