Complex Current Controller Design Based on Multiple Equations Construction of Three-Phase Inverter

Zheng Xinxin,Sun Shangyuan,Liu Xintian,He Yao,Liu Yunbo 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.4

This paper proposes a complex PI current controller design method of three-phase inverter based on multiple equations construction. The mathematical model of three-phase inverter system plays an important role in the controller design process. In the synchronous reference frame, the inverter model introduces coupling elements, which is diff erent from the model in the stationary reference frame and brings diffi culty for current controller design. Complex vector model (CVM) is introduced in the current loop, which is established in the synchronous reference frame and takes part in the current controller design. Multiple equations construction is established to solve the parameters of the complex PI current controller. Because the controller satisfi es the restrictions of the multiple equations, it can realize good dynamic performance and the coupling characteristic of the three-phase system. In this paper, the CVM is established. The process of construct and solve the multiple equations is analyzed in detail. The accuracy of the inverter system is validated. Finally the simulation and experimental results are given to verify the theoretical analysis.

Topology Generation and Analysis of the No Dead Time AC/DC Converter

Xinxin Zheng,Lan Xiao,Yangtian Tian 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.2

A novel topology generation method for the no dead-time three-phase AC/DC converter is proposed in this study. With this method, a series of no dead time topologies are generated and their operation principles are analyzed. The classic three-phase bridge AC/DC converter can realize a bidirectional operation. However, dead-time should be inserted in the driving signals to avoid the shoot-through problem, which would cause additional harmonics. Compared with the bridge topology, the proposed topologies lack the shoot-through problem. Thus, dead time can be avoided. All of the no dead time three-phase AC/DC converters can realize bidirectional operation. The operating principles of the converters are analyzed in detail, and the corresponding control strategies are discussed. Comparisons of waveform distortion and efficiency among the converters are provided. Finally, 9 KW DSP-based principle prototypes are established and tested. Simulation and experimental results verify the theoretical analysis.

Topology Generation and Analysis of the No Dead Time AC/DC Converter

Zheng, Xinxin,Xiao, Lan,Tian, Yangtian The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.2

A novel topology generation method for the no dead-time three-phase AC/DC converter is proposed in this study. With this method, a series of no dead time topologies are generated and their operation principles are analyzed. The classic three-phase bridge AC/DC converter can realize a bidirectional operation. However, dead-time should be inserted in the driving signals to avoid the shoot-through problem, which would cause additional harmonics. Compared with the bridge topology, the proposed topologies lack the shoot-through problem. Thus, dead time can be avoided. All of the no dead time three-phase AC/DC converters can realize bidirectional operation. The operating principles of the converters are analyzed in detail, and the corresponding control strategies are discussed. Comparisons of waveform distortion and efficiency among the converters are provided. Finally, 9 KW DSP-based principle prototypes are established and tested. Simulation and experimental results verify the theoretical analysis.

Current Decoupling Scheme of Three-Phase Inverter with Complex Coefficient Controller

Zheng Xinxin,Xu Jianjun,Shi Jingkui,Huang Wenxin,Li Qiyue 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.6

In the control of three-phase system, AC signals are always changed into DC signals by synchronous coordinate transformation. A decoupling control scheme in the dq synchronous reference frame (SRF) is proposed to realize active and reactive current decoupling of three-phase inverter. The complex vector control model is established in SRF. Diff erent from the model established in static reference frame, the SRF control model can refl ect the coupling characteristic of the active and reactive current. As a result, the PI controller with complex coeffi cient can be applied to realize current decoupling. In this paper, the coupling characteristic of three-phase system is analyzed. A novel complex PI controller design method is proposed based on the SRF control model and the coeffi cients are calculated. And its implementation in the control loop is given. Compared with existing PI controllers with real or complex coeffi cients, the proposed complex PI controller can realize completely the decoupling of the active and reactive current in three-phase system. Besides, the control scheme can make current loop fulfi ll the expected symmetrical bandwidth, so as to realize a higher eff ective set-off frequency. As a result, the inverter can achieve well dynamic performance. Finally, the simulation and experimental results are given to verify the theoretical analysis.

A New Islanding Detection Method Based on Feature Recognition Technology

Xinxin Zheng,Lan Xiao,Wenwen Qin,Qing Zhang 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

Three-phase grid-connected inverters are widely applied in the fields of new energy power generation, electric vehicles and so on. Islanding detection is necessary to ensure the stability and safety of such systems. In this paper, feature recognition technology is applied and a novel islanding detection method is proposed. It can identify the features of inverter systems. The theoretical values of these features are defined as codebooks. The difference between the actual value of a feature and the codebook is defined as the quantizing distortion. When islanding happens, the sum of the quantizing distortions exceeds the threshold value. Thus, islanding can be detected. The non-detection zone can be avoided by choosing reasonable features. To accelerate the speed of detection and to avoid miscalculation, an active islanding detection method based on feature recognition technology is given. Compared to the active frequency or phase drift methods, the proposed active method can reduce the distortion of grid-current when the inverter works normally. The principles of the islanding detection method based on the feature recognition technology and the improved active method are both analyzed in detail. An 18 kVA DSP-based three-phase inverter with the SVPWM control strategy has been established and tested. Simulation and experimental results verify the theoretical analysis.

A New Islanding Detection Method Based on Feature Recognition Technology

Zheng, Xinxin,Xiao, Lan,Qin, Wenwen,Zhang, Qing The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

Three-phase grid-connected inverters are widely applied in the fields of new energy power generation, electric vehicles and so on. Islanding detection is necessary to ensure the stability and safety of such systems. In this paper, feature recognition technology is applied and a novel islanding detection method is proposed. It can identify the features of inverter systems. The theoretical values of these features are defined as codebooks. The difference between the actual value of a feature and the codebook is defined as the quantizing distortion. When islanding happens, the sum of the quantizing distortions exceeds the threshold value. Thus, islanding can be detected. The non-detection zone can be avoided by choosing reasonable features. To accelerate the speed of detection and to avoid miscalculation, an active islanding detection method based on feature recognition technology is given. Compared to the active frequency or phase drift methods, the proposed active method can reduce the distortion of grid-current when the inverter works normally. The principles of the islanding detection method based on the feature recognition technology and the improved active method are both analyzed in detail. An 18 kVA DSP-based three-phase inverter with the SVPWM control strategy has been established and tested. Simulation and experimental results verify the theoretical analysis.

Primary Double Winding Coupling DC Transformer for DC Micro-Grid Applications

Zheng Xinxin,Pan Weijie,Liu Xintian,He Yao 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.3

In recent years, DC micro-grid has attracted widespread attention due to the signifi cant increase in DC loads and the demand for high-quality power. This paper proposes a novel primary double winding coupling topology of the DC transformer (DCT) for DC micro-grid applications. The primary side high-frequency full-bridge inverter is replaced by a novel topology without shoot-through problem. As a result, the reliability of the system is improved, and dead-time is unnecessary to be added to the driving signals thus the dc voltage utilization is higher. Compared to the no dead-time dual-buck inverter, the proposed topology has more advantages in the size and cost, because the primary two windings can be integrated on the same core. What’s more, the infl uence of the leakage inductance can be decreased by the parallel eff ect, so that the transmission effi - ciency of the DCT can be improved. In this paper, the evolution process of the non-dead zone and comparison with other topologies are given. The equivalent circuit and the compensation design are described in detail. The working principle and effi ciency of the proposed topology are analysed and calculated. The simulation and a simple prototype were built up for the experimental tests to verify the advancement of the proposed DCT.

Mechanistic Insight into Nanoarchitected Ag/Pr₆O₁₁ Catalysts for Efficient CO Oxidation

Zhang, Xinxin,Cheng, Shiyang,Zhang, Wei,Zhang, Cai,Drewett, Nicholas E.,Wang, Xiyang,Wang, Dong,Yoo, Seung Jo,Kim, Jin-Gyu,Zheng, Weitao American Chemical Society 2017 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.56 No.39

<P>Ag/Pr<SUB>6</SUB>O<SUB>11</SUB> catalysts supported by either Pr<SUB>6</SUB>O<SUB>11</SUB> nanorods (Pr<SUB>6</SUB>O<SUB>11</SUB>-NRs) or nanoparticles (Pr<SUB>6</SUB>O<SUB>11</SUB>-NPs) were prepared by conventional incipient wetness impregnation. The nanocomposite of Ag/Pr<SUB>6</SUB>O<SUB>11</SUB>-NRs demonstrated a higher catalytic activity for CO oxidation than Ag/Pr<SUB>6</SUB>O<SUB>11</SUB>-NPs at lower temperatures. This improved performance may be ascribed to the mesoporous features and resultant oxygen vacancies of the Pr<SUB>6</SUB>O<SUB>11</SUB> nanorods support, as well as the large surface area and homogeneous loading of Ag species. As a result, 98.7 and 100% CO conversions were achieved at 210 and 240 °C for Ag/Pr<SUB>6</SUB>O<SUB>11</SUB>-NRs, while Ag/Pr<SUB>6</SUB>O<SUB>11</SUB>-NPs require a temperature of 320 °C to obtain the 100% CO conversion rate. These findings reveal that Pr<SUB>6</SUB>O<SUB>11</SUB>-NRs is the preferable support, comparative to Pr<SUB>6</SUB>O<SUB>11</SUB>-NPs, for Ag/Pr<SUB>6</SUB>O<SUB>11</SUB> catalysts, for CO oxidation.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/iecred/2017/iecred.2017.56.issue-39/acs.iecr.7b02530/production/images/medium/ie-2017-02530c_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ie7b02530'>ACS Electronic Supporting Info</A></P>

Passive Islanding Detection Method for Grid‑Connected Inverters Based on Closed‑Loop Frequency Control

Xintian Liu,Xinxin Zheng,Yao He,Guojian Zeng,Yanan Zhou 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.6

Islanding detection is one of the frontier research problems in the study of distributed grid. The non-detection zone of traditional passive detection method is large, and existing active detection methods for non-detection zones are complicated. Aiming at the above problems, this paper proposes a novel passive islanding detection method with the help of closed-loop frequency control (CFC). In this new method, a high-frequency impedance detection method is combined with CFC to prevent the occurrence of islanding, and the frequency tracking principle and high-frequency impedance characteristics of the CFC are analyzed. Load impedance characteristics under diferent islanding conditions are also discussed. Simulation and experimental results show that proposed method is able to detect the occurrence of inverter disconnection quickly and accurately, and non-detection zone is also eliminated.

Equivalent hysteresis model based SOC estimation with variable parameters considering temperature

He, Yao,Li, Qiang,Zheng, Xinxin,Liu, Xintian The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.3

Estimation of the state of charge (SOC) of a lithium-ion battery is one of the key technologies in battery management systems. The accuracy of SOC estimation mainly depends on the accuracy of the battery model. The traditional Thevenin model has limited application due to its fixed parameters. In addition, its accuracy is not high. This paper proposes a variable parameter equivalent hysteresis model based on the Thevenin model. The parameters of this model are regarded as variables that vary with temperature and SOC. They can be identified by hybrid pulse power characteristic (HPPC) experiments. In addition, the model also considers the hysteresis characteristics of the open circuit voltage (OCV) and uses a mathematical recursive equation to describe it. Experimental and simulation results show that the proposed model has a higher accuracy and a wider application than the Thevenin model. On the basis of this model, SOC estimation is carried out based on modified covariance extended Kalman filter (MVEKF) at different temperatures. The results show that the SOC estimation accuracy of the MVEKF method is significantly higher than that of an extended Kalman filter (EKF).