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This paper applies a common-mode modeling approach for a Silicon Carbide (SiC) based medium voltage neutral point clamped (NPC) dual active bridge (DAB) with a 2 level Full-Bridge (2L-FB) stage utilizing an electromagnetic interference (EMI) characterization testbed. A common-mode equivalent circuit model (CEM) for the system is derived, which accurately captures the effect of cross-mode coupling behavior between differential-mode and common-mode caused by circuit asymmetries, such as baseplate capacitance of multi-chip power modules or windings in the transformer. This cross-mode coupling effect is required to accurately model EMI at the higher frequencies of the conducted emissions standards. The derived CEM shows close agreement when compared to the mixed-mode simulation, verifying the model's efficacy. Additionally, baseplate current was shown to be minimized by tying the neutral point of the converter to the heatsink, where this result can be explained through the CEM. The CEM of the NPC DAB will be validated through empirical measurements on an EMI characterization testbed. The testbed features a copper ground plane and custom-built LISNs that can handle the unfiltered harmonic and EMI content of power electronic converters. 

In this study, a sliding mode control (SMC) scheme is proposed for the single-phase cascaded H-bridge (CHB) multilevel active front end (AFE) rectifier with LCL filter. A PI controller is employed to control the DC voltage of the rectifier modules and to obtain the amplitude for the reference grid current. The SMC based current control scheme uses the grid current and filter capacitor voltage feedbacks. The resonance of the LCL filter is damped using the voltage feedback of the capacitor. Therefore, the requirement for additional damping circuitry is removed. Simulation and experimental results are presented to verify the performance of the SMC for the CHB multilevel AFE rectifier. The overall proposed control scheme provides almost unity power factor and fast transient response. It is seen from the results that the current drawn from the grid is in sinusoidal waveform with low THD. 

In this study, a power converter topology and control schemes for the power converter stages are proposed for a DC extreme fast charger. The proposed system is composed of a cascaded H-bridge (CHB) converter as the active front end (AFE), and an input series output parallel (ISOP), which includes three parallel connected dual active bridge (DAB) cells. A modified Lyapunov Function (LF) based control strategy is applied to obtain high current control response for the AFE. An additional controller to remove the voltage unbalances among the H-bridges is also presented. Additionally, the triple phase-shift (TPS) control method is applied for the ISOP DAB converter. A Lagrange Multiplier (LM) based optimization study is performed to minimize the RMS current of the transformer. The performance of the proposed converter topology and control strategies is validated with MATLAB/Simulink simulations. 

The increasing demand for electric vehicles, due to advantages such as higher energy efficiency, lower fuel costs, and less vehicle maintenance, is expected to drive the need for electric vehicle charging infrastructure. Due to their reduced size and weight, high power and scalable compact solid state transformers (SST) are growing in popularity. This study presents the total loss analysis and control design for a direct grid connected single-phase SST for a fast charging station. A control strategy to achieve robust current control, DC voltage and power balancing, and power loss minimization (PLM) is implemented for this system. Detailed analyses and simulation results obtained from MATLAB/Simulink are given to prove the effectiveness of the proposed control techniques. 

In this paper, a 10 kV SiC MOSFET-based solid-state transformer (SST) operating at 13 kV to 7.2 kV, 667 kW, and 20 kHz is modeled and optimized to reach maximum power density and efficiency. In order to reach optimum configuration, different core material/type/size, primary/secondary turns, insulation type/thickness, and cooling systems are considered; then based on a systematic approach the best solution is obtained. To reach this goal, the magnetic part of SST forced air-cooling, and the water-cooling system is modeled in ANSYS MAXWELL/Simplorer, ANSYS-ICEPAK, and ANSYS-FLUENT, respectively. The simulation results show a high efficient SST with an effectiveness of the cooling system. 

The increasing viability of wide band gap power semiconductors, widespread use of distributed power generations, and rise in power levels of these applications have increased interest and need for medium voltage converters. Understanding the definitions of insulation coordination and their relationship to applications and methodologies used in the test environment allows system engineers to select the correct insulation materials for the design and to calculate the required distances between the conductive surfaces, accessible parts and ground accurately. Although, design guidelines are well established for low voltage systems, there are some deficiencies in understanding and meeting the insulation coordination requirements in medium voltage, medium frequency applications. In this study, an overview on standards for insulation coordination and safety requirements is presented to guide researchers in the development of medium voltage power electronic converters and systems. In addition, an insulation coordination study is performed as a case study for a medium frequency isolated DC/DC converter that provides conversion from a 13.8kV AC system to a 4.16kV AC system. 

The primary purpose of this paper is to obtain accurate analytical expressions of the dual active bridge (DAB) converter under the three-degree of freedom control technique. This technique, known as triple phase-shift (TPS) modulation, is utilized for the efficiency optimization of different operating zones and modes of the DAB. Three operating zones and modes have been retained to analyze the converter. Depending on the operating regions and due to the high nonlinearity of the obtained expressions, two optimization techniques have been used. The offline particle swarm optimization (PSO) method is utilized in local optimization (LO) and results in a numerical value. The Lagrange Multiplier (LM) is utilized in global optimization (GO) and results in a closed form expression. In the case of LO, the optimal duty cycles that minimize the power loss are not the optimal values for the minimum root-mean-square (RMS) current or peak current stress. Conversely, in the case of GO, the optimal duty cycles minimize the RMS, peak current and power loss at the same time for the entire power range. Detailed analyses and simulation results from MATLAB/Simulink are given to prove the effectiveness of the proposed method.