More Like this

1. Design and implementation of a series resonant solid state transformer

   https://doi.org/10.1109/ECCE.2017.8095937  

   Rashidi, Mohammad ; Sabbah, Mohamad ; Bani-Ahmed, Abedalsalam ; Nasiri, Adel ; Balali, Mohammad Hasan ( October 2017 , 2017 IEEE Energy Conversion Congress and Exposition (ECCE))

   The focus of this study is on the design of a full-bridge unidirectional resonant LLC Solid State Transformer. The proposed topology uses a high-frequency transformer to optimize the size and weight of the converter. This converter has the capability of operating at fluctuating load conditions while it keeps the voltage regulated in different operation point. The converter is designed to maintain soft switching by using a resonant circuit in this design to minimize the switching loss of the high frequency converter. ZVS in the leading leg for turn on mode and ZCS commutation in the lagging leg for all of the modes are achieved in the H-bridge through the suggested circuitry which is analyzed mathematically in detail in this study. A combination of Pulse frequency modulation (PFM) and Phase Shifting Modulation (PSM) are utilized to control this resonant converter. The experimental setup for the suggested configuration was implemented and the results of the simulation and calculations have been verified with test results. The hardware set up was tested with two different power levels and the output results confirm that the control method works properly to feed the load and keeps the converter working in the expected frequency range and maintainingmore »the soft switching to decrease switching loss. The results shows conversion efficiency of 97.18% is achieved.« less
2. A High Efficiency, Decoupled On-board Battery Charger with Magnetic Control

   https://doi.org/10.1109/ICRERA.2018.8566835  

   Wei, Yuqi ; Altin, Necmi ; Luo, Quanming ; Nasiri, Adel ( October 2018 , International Conference on Renewable Energy and APplications)

   In this paper, a high efficiency, decoupled on-board battery charger is proposed. The proposed topology is composed of two LLC resonant converters sharing the same full-bridge inverter with constant switching frequency. The outputs of two LLC resonant converters are connected in series. One of the LLC resonant converters is operated at the resonant frequency, which is the highest efficiency operation point. The magnetic control is adopted for the second LLC resonant converter to fulfill the closed-loop control of charge voltage and current for constant voltage (CV) and constant current (CC) charge modes. The proposed topology can achieve zero voltage switching (ZVS) for all primary switches and zero current switching (ZCS) for all secondary diodes during both CC and CV modes. Furthermore, thanks to constant frequency operation, the electromagnetic interference (EMI) filter design is simplified. Simulation and experimental studies are presented to verify the feasibility and validity of the proposed topology.
3. A Novel Solar PV Inverter Topology Based on an LLC Resonant Converter

   https://doi.org/10.1109/ECCE.2019.8912924  

   Altin, Necmi ; Ozdemir, Saban ; Nasiri, Adel ( September 2019 , IEEE Energy Conversion Conference and Expo)

   In this paper, a new topology for grid-connected solar PV inverter is proposed. The proposed topology employs an LLC resonant converter with high frequency isolation transformer in the DC-DC stage. The DC-DC converter stage is controlled to generate a rectified sine wave voltage and current at the line frequency. An unfolder inverter interfaces between this DC stage and the grid. Both phase-shift and frequency control methods are used to control the LLC resonant converter. The switching frequency is determined depending on the phase-shift angle to extend the zero-voltage switching (ZVS) region. The transformer leakage and magnetization inductances are also properly designed to provide ZVS for wide operation area. The LLC converter operates in the ZVS region except the narrow band around the zero-crossings of the inverter output current. Since the LLC resonant converter has a high frequency transformer, the line frequency transformer requirement is eliminated, and thus more compact and efficient design is obtained. The proposed topology is validated by the simulation and experimental results.
4. A Control Scheme Based on Lyapunov Function for Cascaded H-Bridge Multilevel Active Rectifiers

   https://doi.org/10.1109/APEC39645.2020.9124234  

   Jean-Pierre, Garry ; Altin, Necmi ; Shafei, Ahmad El ; Nasiri, Adel ( March 2020 , 2020 IEEE Applied Power Electronics Conference and Exposition (APEC))

   The cascaded H-bridge multilevel active rectifier is a prominent converter configuration. It presents compelling advantages, including high adjustability for a number of applications, such as in solid-state transformers, traction applications, medium and high power motor drives and battery chargers. However, when the H-bridge is operating under an unbalanced load and asymmetrical voltage conditions, it becomes important to design advanced control strategies to maintain the stability of the system. In this study, a Lyapunov-function based control method is proposed for controlling the single-phase cascaded H-bridge active rectifier to achieve global asymptotic stability. A capacitor voltage feedback is added to the conventional Lyapunov-function based stabilizing control method to minimize the resonance of the LCL filter. Additionally, a Proportional-Resonant (PR) control approach is adopted to obtain the reference current signal. This increases the robustness of the current control scheme. A DC voltage balancing control procedure is also employed to prevent the unbalanced DC voltage conditions among the H-bridges. The DC voltage is controlled via a PI controller. The capability of the control approach is verified with simulation and experimental studies.
5. Optimal Operation of Multilevel Modular Resonant Switched-Capacitor Converter

   https://doi.org/10.1109/WiPDA.2018.8569135  

   Li, Yanchao ; Ni, Ze ; Cao, Dong ( November 2018 , 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA))

   Multilevel modular resonant switched-capacitor converter can achieve either zero-current switching (ZCS) or zero-voltage switching (ZVS) by utilizing different converter control strategies. This paper presents a comprehensive way to compare the root mean square (RMS) value of current flowing through switching devices in both ZCS operation and ZVS operation. The study shows that with appropriate converter parameter design, the ZVS operation allows the RMS value of switch current at most 10% lower than that in ZCS operation. Therefore, the converter operating at ZVS mode has the potential to achieve higher efficiency comparing to the converter that operates at ZCS mode due to less semiconductor conduction loss. Furthermore, the ZVS operation can reduce the power loss due to MOSFET output capacitance. A 6x converter with 54V input voltage, 9V output voltage and 600W power rating is used as an example to show the detailed design procedure. Simulation results are provided to verify the theoretical analysis. Also, a 600W lab prototype that has 6 to 1 voltage conversion ratio has been built to verify the theoretical analysis.