Neutral Voltage Sensing for Parallel Motor Winding Imbalance
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Solution Overview
Problem
Conventional electric motors with parallel windings face issues of current imbalance due to increased resistance or open circuits, leading to overcurrent stress and potential overheating, which reduces motor reliability.
Innovation Solution
A motor arrangement with voltage sensors connected to neutral buses and a motor controller that monitors current imbalance by calculating differential voltage between neutral buses, allowing for accurate detection of winding failures and implementing countermeasures such as de-rating or shutting down affected phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If parallel windings are used to reduce electrical losses, then energy efficiency is improved, but current imbalance can occur leading to overcurrent stress and overheating
Solution Approach 1:
The patent implements voltage sensing on neutral buses to detect current imbalance between parallel windings. The controller receives feedback signals from voltage sensors and adjusts power distribution to prevent overcurrent conditions, thereby maintaining both energy efficiency and reliability
Solution Approach 2:
The patent replaces mechanical current sensing with electrical voltage sensing on neutral buses. By measuring voltage differentials instead of directly sensing current, the system achieves more accurate and reliable detection of current imbalance without additional mechanical complexity
2Reliability
If voltage sensors and control systems are added to monitor current imbalance, then motor reliability is improved, but device complexity increases
Solution Approach 1:
The patent uses existing neutral buses in the motor winding structure for dual purposes: as electrical connection points and as sensing points for current imbalance detection. This eliminates the need for separate sensing infrastructure and reduces overall system complexity
Solution Approach 2:
The system uses its own neutral bus structure to provide sensing functionality. The existing motor components serve the additional function of enabling current imbalance detection, eliminating the need for external monitoring equipment
3Weight of moving object
If sensor leads with smaller wire gauge are used, then weight and parts quantity are reduced, but sensing capability must be maintained
Solution Approach 1:
The patent changes the sensing approach from direct current measurement to voltage differential measurement on neutral buses. This parameter change allows the use of smaller gauge sensor leads since voltage signals require less current carrying capacity while maintaining measurement precision
Data Source
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AI summary
An electrical machine includes a with a parallel first and second phase windings (122, 124). A first neutral bus (136) is connected to the first phase winding (122) and a second neutral bus (138) is connected to the second phase winding (124). A first voltage sensor (154) is coupled to the first neutral bus (136) and a second voltage sensor (150) is coupled to the second phase winding (124) for monitoring current imbalance between the first and second phase windings (122, 124).