Selective Brush Group Switching for Dynamoelectric Current Density
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Solution Overview
Problem
Dynamoelectric machines face issues with uneven current distribution to electrical brushes, leading to overheating, poor film development, and a risk of flashover due to high variable contact resistance.
Innovation Solution
An arrangement of switches is introduced in the electrical circuit of the electrical brushes to selectively activate or deactivate individual brushes or groups of brushes, adjusting the average current density within a predetermined range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical brushes continuously contact collector rings to pass current, then current transmission is maintained, but uneven current distribution causes overheating and poor film development
Solution Approach 1:
The patent implements periodic switching of brush groups, alternating between first and second groups of brushes at regular intervals. This periodic action distributes the thermal load over time, allowing each brush group to cool down during its inactive period while maintaining continuous current transmission through the active group.
Solution Approach 2:
The patent divides the electrical brushes into multiple independent groups (first group and second group) that can be selectively activated. This segmentation allows the current path to be divided among different brush groups, reducing the current density and thermal load on each individual brush while maintaining overall current transmission.
2Power
If electrical brushes operate at high current levels, then power transmission is improved, but variable contact resistance causes flashover risk
Solution Approach 1:
The periodic switching between brush groups allows the contact surfaces to be refreshed regularly. By alternating which brushes are active, the system prevents prolonged high current through the same contact points, reducing the accumulation of variable contact resistance that leads to flashover while maintaining high power transmission capability.
Solution Approach 2:
The system dynamically changes the operational parameters of the brushes by switching between different groups. This parameter change involves altering which brushes are active and adjusting their duty cycles, thereby controlling the effective current density and contact resistance characteristics to prevent flashover while maintaining power transmission.
3Quantity of substance
If all electrical brushes remain continuously active, then current capacity is maximized, but current density becomes uneven across brushes
Solution Approach 1:
The patent segments the brush population into multiple controllable groups that can be independently managed. By activating only the required number of brushes from these groups at any given time, the system maintains adequate current capacity while ensuring more uniform current distribution across the active brushes, avoiding the uneven density that occurs when all brushes operate simultaneously.
Solution Approach 2:
The system dynamically adjusts which brushes are active based on operational requirements. This dynamic configuration allows optimization of current density distribution by selectively engaging brushes, ensuring uniform current flow across active contacts while maintaining the necessary total current capacity for the application.
Data Source
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AI summary
A system and method for selective activation and deactivation of electrical brushes used in a dynamoelectric machine for current density optimization is disclosed. The approach includes using an arrangement of switches electrically connected to the electrical brushes to selectively activate and deactivate the brushes during the operation of the dynamoelectric machine. This entails opening and closing selective ones of the switches for a predetermined time period to adjust the average current density of the electrical current passing through the electrical brushes to be within a predetermined current density range while the dynamoelectric machine is operating.