End Winding Protections Improvements Helping To Downsize dV/dt Filter For Medium Voltage Machine Fed By NPP Multi-Levels VSI Drive
Bibliographic record
Abstract
In recent years, a growth trend is evident in power electronics from Load Commutated Inverter to Voltage Source Inverter drives based on Neutral Point Piloted 5-levels topology up to 15kV using fast switching devices for better efficiency and compactness. However, a dV/dt filter is required to avoid fast insulation degradation of the motor when exposed to rapid rise repetitive impulses voltage from the Drive. Especially in the ending winding region where preeminent electrical stress is localized toward the slot exit with fast rise time of pulsed voltage. For dV/dt above 3kV/us, traditional corona protection method using conventional stress grading tape is no longer sufficient to prevent the surface discharge and excessive heating at the slot exit. Numerical simulation established in multi-physics finite element analysis indicates that electrical stress distribution and power dissipation at the end winding is closely related to the rise time of drive pulses and stress grading materials properties. New corona protection method is developed based on modeling results and validated on real stator bars under fast pulses. This paper will describe the typical dV/dt patterns generated by those multilevels drives impacting the dV/dt filter and the system of insulation of medium voltage machine. It will also discuss the effectiveness of end winding surface discharge prevention by proper stress grading design and materials selection under high stresses of dV/dt.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".