Electric Machine Insulating Housing Sections Prevent Bearing Currents
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric machines experience bearing currents due to high switching frequencies, leading to rapid wear and failure of bearings through electro-erosion, and existing solutions like ceramic bearings are expensive.
Innovation Solution
The use of light metal alloys with transformed material structures to create electrically insulating sections in the housing and rotor shaft, combined with a rotor shaft grounding ring, prevents bearing currents from flowing through conventional bearings, thereby avoiding damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramic bearings are used to avoid bearing current damage, then bearing reliability is improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent introduces an electrically insulating layer as an intermediary between the bearing and the housing/rotor shaft. This insulating layer prevents bearing currents from reaching the bearing, thereby protecting it without requiring expensive ceramic materials. The insulating layer acts as a mediator that blocks the harmful electrical path while allowing the bearing to remain conventional and cost-effective.
Solution Approach 2:
Instead of using expensive ceramic bearings, the patent employs a cheaper alternative: an electrically insulating layer applied to the housing or rotor shaft. This layer is relatively simple and inexpensive compared to ceramic bearings, yet it effectively prevents bearing current damage, allowing conventional bearings to be used without significant cost increase.
2Ease of manufacture
If conventional bearings are used in electric machines with high switching frequencies, then manufacturing cost is reduced, but bearing currents cause rapid wear and failure
Solution Approach 1:
The electrically insulating layer serves as a protective intermediary that prevents bearing currents from reaching conventional bearings. This allows the use of cost-effective conventional bearings while eliminating the harmful effect of bearing currents, thus maintaining both low cost and high reliability.
Solution Approach 2:
The patent applies preliminary protective action by introducing the electrically insulating layer before bearing currents can cause damage. This preventive measure blocks the harmful electrical paths in advance, preventing electro-erosion and extending bearing life without requiring expensive ceramic materials.
3Reliability
If the housing and rotor shaft are made electrically insulating in sections, then bearing currents are prevented, but material transformation complexity increases
Solution Approach 1:
The patent changes the electrical parameter (conductivity) of specific sections of the housing or rotor shaft by applying electrically insulating layers or using materials with different electrical properties. This localized parameter change creates electrically insulating sections without requiring complete transformation of the entire structure, thereby preventing bearing currents with moderate complexity.
Solution Approach 2:
Instead of making the entire housing or rotor shaft electrically insulating, the patent applies insulation only to specific local sections where bearings are mounted. This localized approach creates the necessary electrical insulation precisely where needed to prevent bearing currents, while leaving other areas unchanged, thus minimizing overall complexity.
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 effectively prevents bearing current-induced damage without the need for expensive ceramic bearings, ensuring the longevity of electric machine components while maintaining cost-effectiveness.
Implementation Method 1
The material structure of the light metal material or light metal alloy material may be transformed using plasma electrochemistry with the configuration of a functionally graded material with the electrically insulating functional layer in the edge layer region
Data Source
AI summary
An electric machine (10) has a rotor (15) and a stator (11). The rotor (15) has a rotor shaft (16) and a rotor laminated core (17). The stator (11) has a housing (12) with a housing cover (14) and a stator laminated core (13). The rotor shaft (16) is mounted rotatably in the housing (12) via bearings (18, 19). Each bearing (18, 19) has a bearing inner ring (18a, 19a) that bears against the rotor shaft (16), and a bearing outer ring (18b, 19b) that bears against the housing (12). Sections (24) of the housing (12) against which the respective bearing outer ring (18b, 19b) bears are formed from a light metal alloy material or a light metal material that has a transformed material structure such that the housing (12) is of electrically insulating configuration in these sections (24).