This page has only limited features, please log in for full access.
Voltage source (VS) control based on inertia synchronization is a novel phase lock loop (PLL)-less autonomous grid-synchronization control strategy suitable for the permanent magnet synchronous generator (PMSG)-based wind turbine. It can autonomously sense grid frequency fluctuations by adopting the dynamics of DC-link capacitor, and it has the advantage of stable operation in an extremely weak grid. This paper further studies the low-voltage ride-through (LVRT) of the PMSG-based wind turbine under the VS control, and presents a wind turbine structure with the additional energy storage battery on the DC side, which not only improves its LVRT capability but also enables the wind turbine to participate in the grid primary frequency regulation. The transient characteristics of VS-controlled wind turbines after the occurrence of the short-circuit fault are analyzed, and a current suppression strategy via switching the virtual resistor in the control loop of the grid-side converter (GCS) is presented. Through coordination with the energy storage battery, the LVRT of the PMSG-based wind turbine is realized, which has the advantage of withstanding a long-time short-circuit fault. Finally, based on the PSCAD/EMTDC simulation platform, the feasibility of the control strategy and the correctness of the theoretical analysis are verified.
Shun Sang; Binhui Pei; Jiejie Huang; Lei Zhang; Xiaocen Xue. Low-Voltage Ride-Through of the Novel Voltage Source-Controlled PMSG-Based Wind Turbine Based on Switching the Virtual Resistor. Applied Sciences 2021, 11, 6204 .
AMA StyleShun Sang, Binhui Pei, Jiejie Huang, Lei Zhang, Xiaocen Xue. Low-Voltage Ride-Through of the Novel Voltage Source-Controlled PMSG-Based Wind Turbine Based on Switching the Virtual Resistor. Applied Sciences. 2021; 11 (13):6204.
Chicago/Turabian StyleShun Sang; Binhui Pei; Jiejie Huang; Lei Zhang; Xiaocen Xue. 2021. "Low-Voltage Ride-Through of the Novel Voltage Source-Controlled PMSG-Based Wind Turbine Based on Switching the Virtual Resistor." Applied Sciences 11, no. 13: 6204.
In recent years, the piezoelectric jet and atomization devices have exhibited tremendous advantages including their simple construction, and the fact that they are discreet and portable as well as low cost. They have been widely used in cell printing, spray cooling, drug delivery, and other industry fields. First, in this paper, two different concepts of jet and atomization are defined, respectively. Secondly, based on these two concepts, the piezoelectric jet and atomization devices can be divided into two different categories: piezoelectric micro jet device and piezoelectric atomization device. According to the organizational structure, piezoelectric micro jet devices can be classified into four different models: bend mode, push mode, squeeze mode, and shear mode. In addition, their development history and structural characteristics are summarized, respectively. According to the location of applied energy, there are two kinds of piezoelectric atomization devices, i.e., the static mesh atomization device and the vibration mesh atomization device, and both their advantages and drawbacks are discussed. The research achievements are summarized in three aspects of cell printing, spray cooling, and drug delivery. Finally, the future development trends of piezoelectric jet and atomization devices are prospected and forecasted.
Qiufeng Yan; Jiahan You; Wanting Sun; Ying Wang; Hongmei Wang; Lei Zhang. Advances in Piezoelectric Jet and Atomization Devices. Applied Sciences 2021, 11, 5093 .
AMA StyleQiufeng Yan, Jiahan You, Wanting Sun, Ying Wang, Hongmei Wang, Lei Zhang. Advances in Piezoelectric Jet and Atomization Devices. Applied Sciences. 2021; 11 (11):5093.
Chicago/Turabian StyleQiufeng Yan; Jiahan You; Wanting Sun; Ying Wang; Hongmei Wang; Lei Zhang. 2021. "Advances in Piezoelectric Jet and Atomization Devices." Applied Sciences 11, no. 11: 5093.
The aluminum electrolytic capacitor (AEC) is one of the most vulnerable parts in power electronic converters and its reliability is crucial to the whole system. With the growth of service time, the equivalent series resistance (ESR) increases and the capacitance (C) decreases due to the loss of electrolytes, which will result in extra power loss and even damage to transistors. To prevent significant damages, the AEC must be replaced at an optimal period and online health monitoring is indispensable. Through the analysis of degradation parameters (ESR and C), ESR is proved to be a better health indicator and therefore is determined as the monitoring parameter for AEC. From the capacitor perspective, ESR estimation schemes of output capacitors for a Buck converter are studied. Based on the voltage–current characteristics, two ESR calculation models are proposed, which are applicable for both continuous conduction mode (CCM) and discontinuous conduction mode (DCM). From the point of implementation view, the advantages and disadvantages of the two estimation schemes are pointed out, respectively. A Buck prototype is built and tested, and simulation and experimental results are provided to validate the proposed ESR estimation schemes.
Lei Ren; Lei Zhang; Chunying Gong. ESR Estimation Schemes of Output Capacitor for Buck Converter from Capacitor Perspective. Electronics 2020, 9, 1596 .
AMA StyleLei Ren, Lei Zhang, Chunying Gong. ESR Estimation Schemes of Output Capacitor for Buck Converter from Capacitor Perspective. Electronics. 2020; 9 (10):1596.
Chicago/Turabian StyleLei Ren; Lei Zhang; Chunying Gong. 2020. "ESR Estimation Schemes of Output Capacitor for Buck Converter from Capacitor Perspective." Electronics 9, no. 10: 1596.
Converter-interfaced doubly-fed induction generators (DFIGs) can provide short-term frequency support (STFS) capability by releasing rotating kinetic energy. After arresting the frequency decrease, the rotor speed should return to its initial operating condition. During the rotor speed recovery process, special attention should paid to the performance of the rotor speed restoration duration and size of the second frequency drop (SFD). This paper suggests an enhanced STFS method of DFIGs to preserve better performance of the frequency nadir with less released rotating kinetic energy and accelerate the rotor speed restoration. To this end, a rotor speed-varying incremental power is proposed and is added to the maximum power tracking (MPT) operation reference during STFS, thereby releasing less rotating kinetic energy from DFIGs; afterward, the power reference smoothly decreases to the reference for MPT operation during the preset period. Test results clearly demonstrate that since even less rotating kinetic energy is utilized, the proposed method can preserve better performance of heightening the frequency nadir; furthermore, the proposed method accelerates the rotor speed restoration when the proposed strategy produces the same SFD as the conventional method, thereby improving the power grid resilience.
Dejian Yang; Hong-Chao Gao; Lei Zhang; Jingjiao Li; Xinsong Zhang; Liang Hua. Fast Frequency Response of a Doubly-Fed Induction Generator for System Inertia Support. Applied Sciences 2020, 10, 2934 .
AMA StyleDejian Yang, Hong-Chao Gao, Lei Zhang, Jingjiao Li, Xinsong Zhang, Liang Hua. Fast Frequency Response of a Doubly-Fed Induction Generator for System Inertia Support. Applied Sciences. 2020; 10 (8):2934.
Chicago/Turabian StyleDejian Yang; Hong-Chao Gao; Lei Zhang; Jingjiao Li; Xinsong Zhang; Liang Hua. 2020. "Fast Frequency Response of a Doubly-Fed Induction Generator for System Inertia Support." Applied Sciences 10, no. 8: 2934.
Efficiency, power quality and reliability of SiC MOSFET-based voltage-source converters are significantly affected by the dead-time settings. The conventional fixed dead-time setting can induce large output voltage loss and additional energy loss due to the output capacitance of the SiC MOSFETs and the SiC SBDs or the freewheeling of the diodes, which will be more serious under high switching frequencies. This paper analyzes and models the detailed switching process of the SiC MOSFET half-bridge circuit when various dead-time settings are adopted. Based on the models, an optimal asymmetric variable dead-time (OAVDT) setting is proposed, which can avoid the discharging loss of the output capacitance and redundant freewheeling loss of the diode. The OAVDT setting is realized by adjusting the optimal dead-time in real time after the active device is turned off, which does not require any additional hardware circuits. The OAVDT setting can also reduce the output voltage loss to a certain level compared to the fixed dead-time setting. A three-phase two-level SiC MOSFET inverter has been built in the lab to verify the proposed OAVDT setting. Experimental results show a decrease of power loss by 22.5% with reduced output voltage loss compared to the fixed dead-time setting of 0.28μs when the output power is 8kW and the switching frequency is 40kHz. The proposed OAVDT setting shows clear advantages over the fixed dead-time setting, especially at light load and high switching frequencies.
Lei Zhang; Xibo Yuan; Jiahang Zhang; Xiaojie Wu; Yonglei Zhang; Chen Wei. Modeling and Implementation of Optimal Asymmetric Variable Dead-Time Setting for SiC MOSFET-Based Three-Phase Two-Level Inverters. IEEE Transactions on Power Electronics 2019, 34, 11645 -11660.
AMA StyleLei Zhang, Xibo Yuan, Jiahang Zhang, Xiaojie Wu, Yonglei Zhang, Chen Wei. Modeling and Implementation of Optimal Asymmetric Variable Dead-Time Setting for SiC MOSFET-Based Three-Phase Two-Level Inverters. IEEE Transactions on Power Electronics. 2019; 34 (12):11645-11660.
Chicago/Turabian StyleLei Zhang; Xibo Yuan; Jiahang Zhang; Xiaojie Wu; Yonglei Zhang; Chen Wei. 2019. "Modeling and Implementation of Optimal Asymmetric Variable Dead-Time Setting for SiC MOSFET-Based Three-Phase Two-Level Inverters." IEEE Transactions on Power Electronics 34, no. 12: 11645-11660.
The higher voltage blocking capability and faster switching speed of SiC MOSFETs has the potential to replace Si IGBTs in medium/low-voltage and high-power applications. In this paper, a state-of-the-art 325A, 1700V SiC MOSFET module has been fully characterized under various load currents, bus voltages and gate resistances to reveal their switching capability. Meanwhile, Si IGBT modules with similar power ratings are also tested under the same conditions. From the test results, several interesting points have been obtained: for example, the over-shoot current of the SiC MOSFET module is greater than that of the Si IGBT module when the load current is high although a SiC Schottky diode is used in the SiC MOSFET module and a PIN diode is used in the IGBT module and a circuit model to explain this phenomenon has been proposed in this paper; the induced negative gate voltage due to the complementary device turn-off (cross-talk effect) is more harmful to the SiC MOSFET module than the induced positive gate voltage during turn-on when the gate off-voltage is -6V. An accurate power loss model which is suitable for a three-phase two-level converter based on SiC MOSFET modules been presented and verified in this paper.
Lei Zhang; Xibo Yuan; Xiaojie Wu; Congcong Shi; Jiahang Zhang; Yonglei Zhang. Performance Evaluation of High-Power SiC MOSFET Modules in Comparison to Si IGBT Modules. IEEE Transactions on Power Electronics 2018, 34, 1181 -1196.
AMA StyleLei Zhang, Xibo Yuan, Xiaojie Wu, Congcong Shi, Jiahang Zhang, Yonglei Zhang. Performance Evaluation of High-Power SiC MOSFET Modules in Comparison to Si IGBT Modules. IEEE Transactions on Power Electronics. 2018; 34 (2):1181-1196.
Chicago/Turabian StyleLei Zhang; Xibo Yuan; Xiaojie Wu; Congcong Shi; Jiahang Zhang; Yonglei Zhang. 2018. "Performance Evaluation of High-Power SiC MOSFET Modules in Comparison to Si IGBT Modules." IEEE Transactions on Power Electronics 34, no. 2: 1181-1196.