In this paper, the impacts of various data integrity attacks on the power electronic hardware present in an EV charger are comprehensively analyzed in order to provide necessary recommendations to defend against cyberattacks on electric vehicles and their onboard charging (OBC) systems. The adverse scenarios arising due to cyberattacks are carefully reviewed in this study, which includes (a) interfering with the main charger controller (FPGA) logic and its data, (b) establishing fake communication between the charging controller and other electronic control units (ECUs) connected over same controller area network (CAN) bus, and (c) interfering with the battery management system functionalities. A 6.6kW interleaved totem-pole PFC front-end followed by a high frequency DC-DC converter is used as our OBC representative system in this analysis. Possibilities and ways of potential cyberattacks on this model are investigated in detail. Effort is made towards providing software as well as hardware design-level protection mechanisms to mitigate the malicious effects of such cyberattacks on the OBC hardware. This system is simulated in MATLAB/Simulink to verify the fault occurrences under various data integrity attacks as well as to validate the effectiveness of our proposed countermeasure approaches. Quantitative analyses of the obtained results clearly demonstrate that if adequate precautionary measures are properly taken while designing the charging architecture (e.g., implementing intelligence to the main controller), any electrical hazard or deterioration of health of the components can be avoided to the maximum extent under the circumstances of a malicious cyberattack.

This article presents the design, development, and optimization of pulsewidth modulation (PWM) scheme of an isolated bidirectional triple-active-bridge (TAB) dc–dc converter composed of three full-bridge modules and a high-frequency planar transformer. This article aims at improving the efficiency of the TAB converter by means of conduction loss minimization. The approach utilizes multiple control variables as degrees of freedom for the converter modulation. The optimization is based on the minimization of the true rms current, formulated using generalized harmonic approximation technique. The approach constitutes of two steps: the modulation pattern with least algorithmic complexity for efficiency maximization is first found depending on the operating load and gain condition, and, subsequently, the optimum control variables are calculated using the gradient descent algorithm applied on the identified modulation pattern. An 800-W TAB converter proof-of-concept is built to verify all theoretical considerations and model-oriented analysis. While the converter has an input dc bus voltage of 160 V, the two output ports of the converter can deliver 400 W each at voltage levels of 110–130 V and 18–27 V, respectively. With the implementation of the proposed optimal phase-duty control, the experimental results show a nonunity gain light load efficiency increment up to 6.1% compared with the conventional modulation technique.

Triple active bridge (TAB) as an isolated multiport dc-dc converter is a promising solution for integrated energy management systems to maintain an efficient power flow between the ports. This paper presents the design, modeling, and switching loss optimized phase-duty controlled PWM modulation scheme of a TAB converter composed of three full-bridge modules and a high-frequency planar transformer. The work aims at the derivation and analysis of the zero-voltage switching (ZVS) conditions for a TAB, where the turn-on switching loss is mitigated along with attaining an improved EMI performance, comprising of reduced noise peaks. Moreover, an optimized five-variable control-based TAB PWM modulation technique is proposed in the paper in order to achieve the minimized switching loss as well as overall system loss for a wide voltage gain and load range. The instantaneous switching currents, responsible for the switching losses at the devices, are derived from the transformer winding current expressions, formulated employing the generalized harmonic approximation (GHA) technique. The various loss minimization techniques and the theoretically obtained criteria for ZVS are experimentally verified using a laboratory-developed prototype of a 800W TAB converter. With the implementation of the proposed optimal phase-duty control, the experimental results show a non-unity gain light load efficiency increment up to 10% compared to the conventional phase shift modulation alone.

This paper presents a novel design and loss optimization technique for a single-stage DC-AC series resonant dual active bridge (SR-DAB) converter through considering a all-harmonic-inclusive general harmonic approximation (GHA) oriented converter model. The proposed work considers the design level optimization of an SR-DAB as well as its control-based optimization by employing a simplified mathematical approach to obtain the LC-tank instantaneous and RMS currents. Also, the ZVS range of operation is vastly improved by applying the GHA model. A series of comparisons in terms of DC-AC RMS currents, ZVS region, and turn-off current of all transistors are conducted at different loads and different modulation techniques to prove the advantage of the proposed optimized design and control optimizations over the traditional dual active bridge (DAB) based DC-AC converters. Finally, a GaN/SiC-based hardware prototype to connect a 40V/500W solar panel to the 120 V _rms AC grid is developed and a quantitative comparison of the efficiencies at different modulation strategies for standard DAB as well as SR-DAB is presented where the proposed design using Advanced Triple Phase Shift (ATPS) modulation exhibits a peak efficiency of 95.8% for the SR-DAB.

Bidirectional onboard chargers introduce electric vehicles (EVs) as flexible actors in the power grids that can operate in grid-to-vehicle (G2V) and vehicle-to-grid (V2G) modes. Despite the benefits of the bidirectional EVs in the event of grid contingencies, they may have adverse impacts on the normal operation of the power systems. This article investigates the impacts of bidirectional EVs on power quality, voltage profile, and frequency stability of the power grid. For this purpose, a detailed model of practical bidirectional onboard charger is presented to measure the total harmonic distortion (THD) in the grid current caused by the EVs. The proposed study accounts for various EV power levels, grid voltage levels, and EV modes of operation. Furthermore, an optimal frequency support strategy is developed that takes advantage of available EVs in V2G mode to improve the frequency stability of the grid in the event of frequency fluctuations. The effects of bidirectional EVs on the voltage profile is also explored by implementing current summation method (CSM)-derived power flow analysis for IEEE 33-Bus radial distribution system. The results show that with an optimal planning of EVs, it is possible to improve voltage profile and frequency stability of the grid while the power quality of the grid is maintained in the allowed range according to the IEEE 519-2014 standard.

In this paper, a switching network loss optimized variable frequency-oriented pulse-width-modulation (PWM) control strategy for a single-stage single phase dc-ac inverter is reported for the application of grid integration of solar PV. The converter is realized by employing a dc-dc high frequency (HF) dual-active-bridge (DAB) stage followed by a low-frequency full-bridge unfolder. To synthesize a loss optimized modulation technique for the converter, the HF switching network losses are precisely quantified by employing a generalized-harmonic-approximation (GHA) based DAB circuit model. Parallel to this, an analytical framework for computing the output voltage total harmonic distortion (THD) under any PWM control strategy is formulated and validated in this paper. Further, based on the mathematical models for loss and THD, a multi-variable multi-constraint loss optimization algorithm is developed that outputs the optimal choice for the converter design as well as control parameters, ensuring an efficient power flow while yielding a better THD and improved electromagnetic interference (EMI) performance. Moreover, the proposed variable-frequency triple-phase-shift (TPS) DAB modulation scheme provides appropriate condition for the zero-voltage-switching (ZVS) of the HF DAB legs over most part of the ac line cycle, while ensuring a minimal turn-off switching current that leads to substantially lower switching loss. A GaN/SiC-based proof-of-concept connecting the 40V/500W solar panel to the 120 Vrms ac grid is developed and its operation under the proposed control scheme is validated at the nominal operating point to verify the formulated analytical models and simulation results. The experimental results conclude that with the application of the proposed optimal modulation scheme, the dc-ac inverter achieves an efficiency and output voltage THD of 96.24% and 2.51%, respectively.