A Common-Mode Voltage Suppression Strategy Based on Double Zero-Sequence Injection PWM for Two-Level Six-Phase VSIs

A common-mode voltage (CMV) suppression strategy, namely double zero-sequence injection common-mode voltage (DZICMV), is proposed in this paper for an asymmetrical six-phase induction motor fed by two-level dual three-phase voltage source inverters (VSIs). In this strategy, the sinusoidal waveforms injected by double zero-sequence signals are employed as modulation signals, and two opposite triangular waveforms are used as carriers. The fundamental period is divided into 24 sectors. In each sector, the carrier used by the medium amplitude phase is distinct from the carriers used by the other two phases in each set of three-phase windings. Using this method, the zero vectors (000) and (111) in each set of three-phase windings can be eliminated, and the peak values of sub-CMV and total CMV can be reduced from ±Udc/2 to ±Udc/6. The experiment results show that the root mean square (RMS) value of common-mode leakage current in DZICMV can be reduced by 51.83% compared with the double zero-sequence injection PWM (DZIPWM) strategy. It is also found in the other four existing benchmark CMV suppression strategies that the peak values of sub-CMV therein are nearly all ±Udc/2, and only in the low linear modulation region could one of these strategies suppress sub-CMV peak values to ±Udc/6. However, the proposed DZICMV can suppress the sub-CMV peak values to ±Udc/6 in the whole linear modulation range. Moreover, the maximum linear modulation index of the DZICMV is 1.15, which is larger than that of the four benchmark strategies, whose maximum modulation index is 1

Design and Implementation of Recursive Model Predictive Control for Permanent Magnet Synchronous Motor Drives

In order to control the permanent-magnet synchronous motor system (PMSM) with different disturbances and nonlinearity, an improved current control algorithm for the PMSM systems using recursive model predictive control (RMPC) is developed in this paper. As the conventional MPC has to be computed online, its iterative computational procedure needs long computing time. To enhance computational speed, a recursive method based on recursive Levenberg-Marquardt algorithm (RLMA) and iterative learning control (ILC) is introduced to solve the learning issue in MPC. RMPC is able to significantly decrease the computation cost of traditional MPC in the PMSM system. The effectiveness of the proposed algorithm has been verified by simulation and experimental results

Role of WDHD1 in Human Papillomavirus-Mediated Oncogenesis Identified by Transcriptional profiling of E7-expressing cells

The E7 oncoprotein of the high-risk human papillomavirus (HPV) plays a major role in HPV-induced carcinogenesis. E7 abrogates the G(1) cell cycle checkpoint and induces genomic instability, but the mechanism is not fully understood. In this study, we performed RNA sequencing (RNA-seq) to characterize the transcriptional profile of keratinocytes expressing HPV 16 (HPV-16) E7. At the transcriptome level, 236 genes were differentially expressed between E7 and vector control cells. A subset of the differentially expressed genes, most of them novel to E7-expressing cells, was further confirmed by real-time PCR. Of interest, the activities of multiple transcription factors were altered in E7-expressing cells. Through bioinformatics analysis, pathways altered in E7-expressing cells were investigated. The upregulated genes were enriched in cell cycle and DNA replication, as well as in the DNA metabolic process, transcription, DNA damage, DNA repair, and nucleotide metabolism. Specifically, we focused our studies on the gene encoding WDHD1 (WD repeat and high mobility group [HMG]-box DNA-binding protein), one of the genes that was upregulated in E7-expressing cells. WDHD1 is a component of the replisome that regulates DNA replication. Recent studies suggest that WDHD1 may also function as a DNA replication initiation factor as well as a G(1) checkpoint regulator. We found that in E7-expressing cells, the steady-state level of WDHD1 protein was increased along with the half-life. Moreover, downregulation of WDHD1 reduced E7-induced G(1) checkpoint abrogation and rereplication, demonstrating a novel function for WDHD1. These studies shed light on mechanisms by which HPV induces genomic instability and have therapeutic implications. IMPORTANCE The high-risk HPV types induce cervical cancer and encode an E7 oncoprotein that plays a major role in HPV-induced carcinogenesis. However, the mechanism by which E7 induces carcinogenesis is not fully understood; specific anti-HPV agents are not available. In this study, we performed RNA-seq to characterize transcriptional profiling of keratinocytes expressing HPV-16 E7 and identified more than 200 genes that were differentially expressed between E7 and vector control cells. Through bioinformatics analysis, pathways altered in E7-expressing cells were identified. Significantly, the WDHD1 gene, one of the genes that is upregulated in E7-expressing cells, was found to play an important role in E7-induced G(1) checkpoint abrogation and rereplication. These studies shed light on mechanisms by which HPV induces genomic instability and have therapeutic implications

A Harmonic Suppression SVPWM Strategy for the Asymmetric Six-Phase Motor Fed by Two-Level Six-Phase VSI Operating in the Overmodulation Region

For the asymmetric six-phase motor fed by a two-level six-phase voltage source inverter (VSI), when the modulation index is less than 0.5774, the motor operates in the linear region, and the harmonics in the Z1 − Z2 subspace can be suppressed to zero. When the modulation index is beyond 0.5774 and less than 0.6221, the motor operates in overmodulation regions, and the harmonics in the Z1 − Z2 subspace cannot be suppressed to zero. To minimize the harmonics in the Z1 − Z2 subspace for these regions, a harmonic suppression strategy, namely, harmonic suppression overmodulation strategy (HSOS), is proposed in this paper. The lower-order harmonics of the Z1 − Z2 subspace, namely, the 5th, 7th, 17th and 19th, are considered. Compared with the traditional four-vector overmodulation strategy (TFOS), the content of the 5th harmonic is reduced by about 20%, and the total harmonic distortion (THDZ1Z2) of these four kinds of harmonics is reduced by about 21% in the proposed HSOS. Finally, the simulation and experiment are carried out to verify the effectiveness of the proposed strategy