Space‑Vector‑Based Hybrid PWM for Zero‑Sequence‑Circulating‑Current RMS and Common Mode Voltage Reduction in Two Parallel Interleaved Two‑Level Converters

Zhiyong Zeng,Zhongxi Li,Stefan M. Goetz 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.3

This paper aims at reducing the root mean square (RMS) values of the zero-sequence circulating current (ZSCC). The analysis reveals that the ZSCC is determined by the duty ratios of the medium voltage vector and zero vector. Whereas the reference voltage fxes the duty ratio of the medium vector, the duty ratio of the zero-voltage vector depends on the distribution of the small and larger vectors, which can be used to optimize the ZSCC. As such, we propose a generalized PWM architecture, where the distribution of the active vectors is parameterized by a coefcient k. Based on this, we derive regions for k that attain the same minimal ZSCC peak. Within these regions, we further optimize k to minimize the ZSCC RMS. Depending on the reference voltage, the method selects diferent coefcient k for the ZSCC RMS optimizations. The proposed modulation strategy is therefore a HBSVM due to its adaptive feature in the distribution of the active vectors. The proposed HBSVM uniformly applies to the entire vector plane and is computationally afordable for mainstream microcontrollers. Finally, the experimental results validate the merits of the proposed method.

Flatbands and Emergent Ferromagnetic Ordering in Fe3Sn2 Kagome Lattices

Lin, Zhiyong,Choi, Jin-Ho,Zhang, Qiang,Qin, Wei,Yi, Seho,Wang, Pengdong,Li, Lin,Wang, Yifan,Zhang, Hui,Sun, Zhe,Wei, Laiming,Zhang, Shengbai,Guo, Tengfei,Lu, Qingyou,Cho, Jun-Hyung,Zeng, Changgan,Zhan American Physical Society 2018 Physical Review Letters Vol.121 No.9

Performance Analysis and Comparison of Post-Fault PWM Rectifiers Using Various Space Vector Modulation Methods

Chong Zhu,Zhiyong Zeng,Rongxiang Zhao 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6

In this paper, some crucial performance characteristics related to the operational reliability of the post-fault Pulse Width Modulated (PWM) rectifiers, such as line current harmonic distortion, Common Mode Voltage (CMV), and current stress on the capacitors, are fully investigated. The aforementioned performance characteristics of post-fault rectifiers are highly dependent on the utilized space vector modulation (SVM) schemes, which are also examined. Detailed analyses of the three most commonly used SVM schemes for post-fault PWM rectifiers are provided, revealing the major differences in terms of the zero vector synthesis approaches. To compare the performances of the three SVM schemes, the operating principles of a post-fault rectifier are presented with various SVM schemes. Using analytical and numerical methods in the time domain, the performances of the line current distortion, common mode voltage and capacitor current are evaluated and compared for each SVM scheme. The proposed analysis demonstrates that the zero vector synthesis approaches of the considered methods have significant impacts on the performance characteristics of rectifiers. In addition, the advantages and disadvantages of the proposed SVM schemes are discussed. The experimental results verify the effectiveness and validity of the proposed analysis.

Direct Stator Flux Vector Control Strategy for IPMSM using a Full-order State Observer

Yuan, Qingwei,Zeng, Zhiyong,Zhao, Rongxiang The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.1

A direct stator flux vector control scheme in discrete-time domain is proposed in this paper for the interior permanent magnet synchronous motor (IPMSM) drive to remove the proportional-integral (PI) controller from the direct torque control (DTC) scheme applied to IPMSM and to obtain faster dynamic response and lower torque ripple output. The output of speed outer loop is used as the desired torque angle instead of the desired torque in the proposed scheme. The desired stator flux vector in dq coordinate is calculated with a given amplitude. The state-space equations in discrete-time for IPMSM are established, the actual stator flux vector is estimated in deadbeat manner by a full-order state observer, and then the closed-loop control is achieved by the pole placement. The stator flux error vector is utilized to calculate the reference stator voltage vector. Extracting the angle position and amplitude from the estimated stator flux vector and estimating the output torque are eliminated for the direct feedback control of the stator flux vector. The proposed scheme is comparatively investigated with a PI-SVM DTC scheme by experiment results. Experimental results show the feasibility and advantages of the proposed control scheme.

Direct Stator Flux Vector Control Strategy for IPMSM using a Fullorder State Observer

Qingwei Yuan,Zhiyong Zeng,Rongxiang Zhao 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.1

A direct stator flux vector control scheme in discrete-time domain is proposed in this paper for the interior permanent magnet synchronous motor (IPMSM) drive to remove the proportional-integral (PI) controller from the direct torque control (DTC) scheme applied to IPMSM and to obtain faster dynamic response and lower torque ripple output. The output of speed outer loop is used as the desired torque angle instead of the desired torque in the proposed scheme. The desired stator flux vector in dq coordinate is calculated with a given amplitude. The state-space equations in discrete-time for IPMSM are established, the actual stator flux vector is estimated in deadbeat manner by a full-order state observer, and then the closed-loop control is achieved by the pole placement. The stator flux error vector is utilized to calculate the reference stator voltage vector. Extracting the angle position and amplitude from the estimated stator flux vector and estimating the output torque are eliminated for the direct feedback control of the stator flux vector. The proposed scheme is comparatively investigated with a PI-SVM DTC scheme by experiment results. Experimental results show the feasibility and advantages of the proposed control scheme.

Performance Analysis and Comparison of Post-Fault PWM Rectifiers Using Various Space Vector Modulation Methods

Zhu, Chong,Zeng, Zhiyong,Zhao, Rongxiang The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.6

In this paper, some crucial performance characteristics related to the operational reliability of the post-fault Pulse Width Modulated (PWM) rectifiers, such as line current harmonic distortion, Common Mode Voltage (CMV), and current stress on the capacitors, are fully investigated. The aforementioned performance characteristics of post-fault rectifiers are highly dependent on the utilized space vector modulation (SVM) schemes, which are also examined. Detailed analyses of the three most commonly used SVM schemes for post-fault PWM rectifiers are provided, revealing the major differences in terms of the zero vector synthesis approaches. To compare the performances of the three SVM schemes, the operating principles of a post-fault rectifier are presented with various SVM schemes. Using analytical and numerical methods in the time domain, the performances of the line current distortion, common mode voltage and capacitor current are evaluated and compared for each SVM scheme. The proposed analysis demonstrates that the zero vector synthesis approaches of the considered methods have significant impacts on the performance characteristics of rectifiers. In addition, the advantages and disadvantages of the proposed SVM schemes are discussed. The experimental results verify the effectiveness and validity of the proposed analysis.

Effects of raw meat and process procedure on N^ε-carboxymethyl-lysine and N^ε-carboxyethyl-lysine formation in meat products

Yu, Ligang,Gao, Chang,Zeng, Maomao,He, Zhiyong,Wang, Linxiang,Zhang, Shuang,Chen, Jie 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.4

This work aimed to investigate the effects of stored raw meat and process procedures on $N^{\varepsilon}$-carboxymethyl-lysine (CML) and $N^{\varepsilon}$-carboxyethyl-lysine (CEL) generation in meat products. Meat products of raw pork were sterilized and pasteurized at different storage times (0-4 months) and the CML/CEL contents were determined. The results showed that the extent of lipid and protein oxidation of raw pork increased with increasing storage time. A linear correlation was found between thiobarbituric acid-reactive substances value/carbonyl content and CML/CEL in sterilized meat products, indicating that stored raw pork could promote CML/CEL formation under high temperature processing. Furthermore, mild heating temperatures seemed to favor CML formation, while high temperature could accelerate CEL generation. Therefore, formation kinetics of CML and CEL might be different for different process procedures. These results suggested that stored raw meat and processing temperature could significantly affect CML and CEL generation in meat products.

Influence of the Electrolytic Dy-Cu alloy on the Coercivity of Sintered Nd-Fe-B Magnet

Chun-fa Liao,Xun Zhou,Peng Jiang,Zhiyong Zeng,Lianghua Que 한국자기학회 2022 Journal of Magnetics Vol.27 No.4

The fluorine salt oxide molten-salt electrolytic Dy-Cu alloy was used as a grain boundary diffusion source instead of the doped Dy-Cu alloy. The microstructure and coercivity of the GBDPed magnets with the different diffusion times were studied. The results show that the coercivity increased with the increase in the GBDP time. The ability of the electrolytic Dy-Cu alloy to improve the coercivity of Nd-Fe-B is more advantageous than that of the doped Dy-Cu alloy. Microstructure analysis shows that the segregation and metal inclusion, a small amount of Dy2O3, and the poor synergy diffusion between Dy and Cu lead to the unsatisfactory performance of the doped Dy-Cu alloy to improve the coercivity. The diffusion rate and depth of the GBD source improved by replacing the doped alloy with an electrolytic alloy.

Effects of raw meat and process procedure on Nε-carboxymethyllysine and Nε-carboxyethyl-lysine formation in meat products

Ligang Yu,Chang Gao,Maomao Zeng,Zhiyong He,Linxiang Wang,Shuang Zhang,Jie Chen 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.4

This work aimed to investigate the effects of stored raw meat and process procedures onNε-carboxymethyl-lysine (CML) and Nε-carboxyethyl-lysine (CEL) generation in meat products. Meatproducts of raw pork were sterilized and pasteurized at different storage times (0-4 months) and theCML/CEL contents were determined. The results showed that the extent of lipid and protein oxidationof raw pork increased with increasing storage time. A linear correlation was found betweenthiobarbituric acid-reactive substances value/carbonyl content and CML/CEL in sterilized meatproducts, indicating that stored raw pork could promote CML/CEL formation under high temperatureprocessing. Furthermore, mild heating temperatures seemed to favor CML formation, while hightemperature could accelerate CEL generation. Therefore, formation kinetics of CML and CEL might bedifferent for different process procedures. These results suggested that stored raw meat andprocessing temperature could significantly affect CML and CEL generation in meat products.

Magnetic Properties and Microstructure of DyAlCu-diffusion Sintered Nd-Fe-B Magnets

Chunfa Liao,Xun Zhou,Peng Jiang,Zhiyong Zeng,Lianghua Que 한국자기학회 2022 Journal of Magnetics Vol.27 No.2

The ability to improve the coercivity of sintered Nd-Fe-B diffused by Dy-Al-Cu alloy derived from electrolysis in a fluoride salt-oxide system was evaluated. The results show that with the increase in heat treatment time, the coercivity of the magnet firstly increased and then decreased. Holding at 900 ℃ for 4 h, tempering at low temperature for 3 h at 550 ℃, the coercivity of GBDPed magnet increased by 44.34 %, the remanence decreased by 1.26 %, the Dy-rich shell phase was recognizable, and the Nd-rich phase evenly distributed. Electron microscope analysis showed that when the GBDP time was longer than 4h, the diffusion of Dy from the shell phase to the matrix phase dominated, decreasing the coercivity with the increase in the diffusion time. The increase of Fe content in the grain boundary phase enhanced the exchange coupling between grains, which also reduced the coercivity of the GBDPed magnet. The infiltration of the matrix phase by excessive Dy and deterioration of (00L) texture of Nd-Fe-B resulted in the reduction of the remanence and the maximum energy product.