Modified Carrier-Overlapped PWM With Balanced Capacitors and Eliminated Dead-Time Spikes for Four-Level NNPC Converters Under Low Frequency
Bibliographic record
Abstract
Due to the lack of sufficient redundant states, four-level nested neutral-point clamped (4L-NNPC) converters suffer from severe flying capacitor (FC) voltage fluctuations under low fundamental frequencies, which restricts their applications in practice. To deal with this issue, a modified carrier-overlapped pulsewidth modulation (PWM) (COPWM) is proposed in this article, which could achieve zero average current flow through the two FCs over each carrier period. As a result, their voltages can be balanced naturally under steady states theoretically, and the low-frequency FC voltage fluctuation issue would no longer exist. In order to compensate for any nonideal factors in real industrial applications, an active control by dynamically adjusting the correspondence between carriers and switches is further applied for better control performance. A dead-time compensation scheme is proposed accompanied by this modified COPWM to eliminate the unexpected dead-time-induced voltage spikes of 4L-NNPC converters. The effectiveness of the proposed modified COPWM in regulating the FCs under low frequency and eliminating the dead-time-induced voltage spikes is verified by both simulation and experimental results.
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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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".