This article presents a dual-side capacitor tuning and cooperative control strategy for wireless electric vehicle (EV) charging. To improve the efficiency of wireless EV charging across broad output voltages and wide-range load variations, this article introduces a reconfigurable WPT system by incorporating two switch-controlled-capacitors (SCCs) into the double-sided LCC (DLCC) compensation network. Based on the analytical model of the system, optimal capacitor tuning factors are derived to reduce the rms values of the inductor currents and to minimize the turn-off currents across the semiconductors. Furthermore, a dual-side cooperative control strategy is proposed. Through the collaborative control of the inverter, rectifier, and SCCs, the proposed method achieves dual-side optimal zero-voltage-switching (ZVS), wide power regulation, and maximum efficiency tracking simultaneously. Compared with the existing triple-phase-shift (TPS) method, the proposed approach improves the system efficiency across a wide range of dc output voltages and power levels. Experimental results demonstrate that the proposed method achieves a maximum efficiency improvement of up to 1.8% in the boost mode and 1.9% in the buck mode.

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In this chapter, various electric vehicle (EV) charging technologies are reviewed, including onboard charging, offboard charging, and contactless charging. The focus is on charging power control as well as its converter topology. Because EV charging significantly influences the grid, the power quality of EV charging is thoroughly reviewed in terms of modeling, analysis, and mitigation measures. EV charging, especially overnight, gives a lot of flexibility to instant charging power, which can be used to improve the load flow in the electric grid. Smart charging describes those approaches, which are also reviewed.

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This paper introduces variable-frequency zero voltage switching (ZVS) modulation strategy for the four-switch buck+boost converter with one operating pattern for the inductor current, i.e., three-segment inductor current modulation control. The proposed modulation scheme guarantees a smooth transition from step-up to step-down or from step-down to step-up operating modes without abrupt duty cycle or switching frequency change. Triangular current mode (TCM) ZVS control could be derived from this three-segment inductor current modulation strategy. Moreover, the controller design can be simplified compared with other multi-mode control methods. Experimental results were given to validate the modulation control strategy based on a 300−600 V input, 400 V output, 3.3 kW prototype.@en

This paper proposes two modulation schemes for Dual Active Bridge (DAB) converters, with the aim of maximizing Zero Voltage Switching (ZVS) operation over a wide operational range. The first is a ZVS-optimized constant frequency modulation scheme, constructed based on the boundary conditions of ZVS operation. This scheme maximizes the number of ZVS events across a broad operational range and is easy to implement. Additionally, a variable frequency modulation scheme is proposed, enabling continuous full ZVS operation for the DAB converter at full power and eliminating the loss of ZVS due to transitioning between modulation regions. This functionality extends the full ZVS range, yielding improved Electromagnetic Interference (EMI) performance and overall power efficiency. The synergy of the proposed modulation schemes is particularly well-suited for applications like off-board Electric Vehicle (EV) charging. Experimental validation, conducted on an 11-kW DAB converter prototype with an output voltage range of 250V to 950V, demonstrates the efficacy of the proposed schemes in achieving ZVS and boosting converter efficiency.

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This article gives an overview of challenges in primary distribution, protections, and power scalability for shipboard dc systems. Given that dc technology is in development, several aspects of shipboard systems have not yet been sufficiently devised to ensure the protection and efficiency demanded. Several issues in dc systems arise from the lack of complete relevant standardization from different regulation bodies. Unipolar and bipolar bus architectures have application-specific advantages that are discussed and compared. The placement of power electronics in dc systems creates opportunities for switchboard design, and this article compares the centralized and distributed approaches. Likewise, protection architectures for shipboard dc systems have challenges. Breaker-based protection utilizes slow fuses, mechanical circuit breakers, and solid-state circuit breakers. In addition, power-electronics-based protection embeds the protective circuit in the power converters, but its development lags. This article compares the state-of-the-art technologies, reviewing their main features. Finally, the power requirement of various applications and the low production rate of vessels force the designers to utilize commercial off-the-shelf converters to scale up power. The misuse of such converters, the modular topologies, and power electronics building blocks are exposed highlighting challenges and opportunities toward the mass adoption of dc systems onboard maritime vessels.

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The lithium-ion battery of an electric vehicle (EV) is typically rated at either 400 or 800 V. When considering public parking infrastructures, EV wireless chargers must efficiently deliver electric power to both battery options. This can be normally achieved by regulating the output voltage through a dc-dc converter at the cost of higher onboard circuit complexity and lower overall efficiency. This article proposes a wireless charging system that maintains a high power transfer efficiency when charging EVs with either 400- or 800-V nominal battery voltage at the same power level. The control scheme is implemented at the power source side, and only passive semiconductor devices are employed on board the EV. The presented system, called voltage/current doubler (V/I-D), comprises two sets of series-compensated coupled coils, each of them connected to a dedicated H-bridge converter. The equivalent circuit has been analyzed while explaining the parameters' selection. The analytical power transfer efficiency has been compared to the one resulting from the conventional one-to-one coil system at 7.2 kW. For the same power level, the dc-to-dc efficiency of 97.11% and 97.52% have been measured at 400-V and 800-V voltage output, respectively. Finally, the functionality of the V/I-D converter has been proved at both the even and uneven misalignments of the two sets of coupled coils.

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The sinusoidal Triangular-Current-Mode (S-TCM) method has been proposed in the AC/DC power-factor-correction (PFC) converter to achieve the zero-voltage-switching (ZVS) which can lead to both, high efficiency operation and a high power density design. Nevertheless, the necessary wide range variation of the sinusoidal switching frequency profile imposed by the S-TCM results in a larger generated voltage harmonic peak due to the overlapping between different order carrier-frequency harmonics. In this work, the S-TCM is used in the interleaved 2-level converter to minimize the undesirable effects of such overlapped voltage harmonics while maintaining ZVS via S-TCM. Meanwhile, the necessity of coupled inductors (CIs) in the interleaved topology is avoided by implementing the S-TCM. Both simulation and experimental tests conducted in a 3.3 kW interleaved 2-level converter system are used to verify the study.

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A Modular Multilevel Converter (MMC)-based Arbitrary Wave shape Generator (AWG) for High Voltage (HV) testing faces challenges in the control hardware to generate kHz-range high-frequency waveforms. Real Time Simulators (RTS) provide a simple way to implement the control of the MMC-based AWG in the FPGA. One of the commercially available RTS named Typhoon HIL is found to satisfy the small simulation step requirement such as minimum of 200 ns for generating kHz-range high-frequency waveforms. The performance of Typhoon HIL device is demonstrated with a scaled-down prototype of MMC-based AWG where sinusoidal and other arbitrary waveforms are generated up to 5kHz with a THD less than 5 %.@en

In this article, a reconfigurable two-stage dc/dc resonant topology with a wide output voltage range of 150-1000 V is proposed for electric vehicle (EV) charging with high efficiency over the entire load range. The proposed topology consists of an LLC resonant converter with dual secondary sides; two interleaved triangular current mode (TCM) buck converters, and three additional auxiliary switches for reconfiguration. Two possible arrangements of the proposed topology are considered and compared. The analytical model of the topology is developed, which is used for the efficiency estimation of different configurations and the design of the prototype converter. An 11 kW hardware demonstrator is built and tested. The maximum measured efficiency of the converter is 97.66%, with a >95% efficiency over the complete 150-1000 V range at full power. The proposed two-stage converter achieves the widest output voltage range reported in literature for resonant power converters (RPCs), thereby capable of charging existing and future EVs very efficiently over any charging cycle.

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Compact and efficient power converter solutions are seen to be the backbone of future transportation systems in order to cope with the ongoing transition toward greener systems. Such systems usually comprise a main load section, in which one or more propulsion or traction motors are connected, in addition to an auxiliary load, which might comprise the hotels and air conditioning for example. This auxiliary load can be as low as 5-10% of the main load power. Therefore, it can be challenging to drive this power from a typical high-power system that employs a medium-voltage (MV) dc (MVDC) grid, which is typical in high-power systems. In such MVDC-integrated systems, neutral-point-clamped and active neutral-point-clamped (ANPC) converters are commonly used, where the auxiliary load converter is overrated in this case, resulting in a bulky and inefficient power system. Thus, in order to enable a lighter and efficient transportation power system, a multiport hybrid converter (MHC) is presented in this article. This converter can feed the main MV motor, in addition to two auxiliary low-voltage loads. Compared with the state-of-the-art ANPC converter, the proposed MHC utilizes only two extra switches per phase leg in order to achieve this multiport operation along with increasing the voltage rating of another two switches. The proposed MHC is analyzed in this article, where its operation, modulation, and mathematical derivation are presented. These analyses are supported by simulation and experimental results utilizing a reduced-scale 5-kW system.

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With the great emphasis from the international standard-setting community on the so-called supra-harmonics emissions (2-150 kHz), there are increasing research efforts in this noise level identification, measurement, standard setting and mitigation. The periodic variable switching frequency PWM method, which is known as VSFPWM, can reshape the generated output harmonics spectrum of the grid-connected PWM converter, leading to a significantly lower harmonics peaks, thus keeping the harmonics emission strictly below the harmonics emission standards e.g., IEEE519 & IEC-61000 series. This work conducted an insightful analysis on the harmonics spectra generated by the periodic VSFPWM based on newly derived analytical models. Besides, the sinusoidal VSFPWM which is often used in AC/DC PWM converter, is taken as an example of periodic VSFPWM profile to achieve the minimum efforts of AC filtering. Finally, experimental tests are conducted to verify the analysis and the design guideline provided in this paper.@en

This work proposes a hybrid space vector modulation (HSVM) scheme for multiport hybrid converters (MHCs). Moreover, the impact of shifting the auxiliary currents from the main ones is proposed and investigated in order to enhance the converter efficiency. The proposed operational schemes have been implemented in a three-phase 5 kW MHC prototype. It is shown that the proposed HSVM scheme can improve the MHC efficiency by 0.3% at full load with respect to space vector modulation. At partial loads, the improvement is even more significant, reaching +0.7% at 30% of the rated power. A further 0.15% increase in efficiency at full power can be achieved by a 180$^{\circ }$ phase shifting of the auxiliary currents with respect to the main terminal currents, reaching a peak efficiency of 98.5%.

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To test high-voltage (HV) equipment with increasingly complex transients obtained from various power system studies, this article demonstrates a hardware implementation of a medium-voltage (MV) submodule (SM) to be used in a modular multilevel converter (MMC)-based HV arbitrary wave shape generator (AWG). The MV SM is scalable with its own onboard auxiliary power supply (APS), and it is constructed by connecting three full-bridge SMs in series from the commercially available component. The designed MV SM can be operated for a wide voltage range of 0.8-2.7 kV to incorporate different test objects ranging from HV insulation material to MV equipment and generate a wide output range of 0.12-1.2 kV. Considering the hardware nonidealities in the APS, gate driver, and switches, the series operation of three SMs is ensured using an arm energy controller. Based on the current-based model of APS, SM capacitance design criteria are updated for variable-frequency output waveform, and the minimum dc-link voltage is calculated for the proper start-up of this scalable MMC module. Apart from the variable voltage per SM, the HV AWG application poses different conditions, such as a low value of SM capacitance value and the HV dc sources with a current rating of a few tens of milliamperes. Hence, this article proposes exclusive design guidelines for the proper start-up, steady-state, and shutdown operation of the MMC-based AWG. In addition, this article dives deeper analytically into the soft start-up algorithm to understand its working principle and to design the average charging current within the limit for any number of SMs of the arm. In the end, their performance is showcased with a single MV SM per arm, operating at a different voltage (0.8-2.7 kV) and frequency levels (1-600 Hz) and generating different wave shapes, such as triangular, sinusoidal with different harmonics, and pulse waveforms. In addition, the fault ride-through capability is verified for the MMC-based HV AWG.

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In order to damp the resonance in the MMC-based Arbitrary Wave shape Generator (AWG) used for high voltage testing, an active damping control methodology is proposed in this paper instead of the passive damping with an arm resistor. It is vital to ensure the system’s stability when such an active damping closed loop control is implemented. Consequently, optimal parameters of a PI controller are designed by analyzing the stability margins of the involved transfer function using Bode-Plots. The performance of the designed active damping control methodology and the PI controller have been demonstrated with a 50 Hz sinusoidal waveform and arbitrary waveforms such as triangular, trapezoidal, and complex waveforms in MATLAB-Simulink. These results proves that the output voltage can track the reference without any reasonable error and does not contain any resonant frequency. Additionally, the Total Harmonic Distortion (THD) of the sinusoidal waveform and other arbitrary waveforms is less than 1% with the Phase Shift Carrier (PSC) modulation technique.@en

Light-duty electric vehicles (EVs) typically have a rated voltage of either 400 or 800 V. Especially when considering public parking infrastructures or owners with multiple EVs, e.g., car rental companies, EV wireless chargers must efficiently deliver electric power to both battery options. For this purpose, this article proposes an advanced and compact version of the previously defined voltage/current doubler (V/I-D) converter, here comprising two coupled series-compensated bipolar pads (BPPs). The presented system can efficiently charge EVs with both battery voltage classes at the same power level without affecting the current rating of the converter's circuit components. The control scheme is implemented at the power source side in terms of switching frequency and input voltage, and only passive semiconductor devices are employed on board the EV. The equivalent circuit is analyzed, focusing on the BPPs' undesired cross-coupling and its effect on the power transfer. Methods to compensate for the cross-coupling are proposed regarding the BPP design and operating strategy. At 7.2 kW and aligned BPPs, the dc-to-dc efficiency of 96.34% and 96.53% have been measured at 400 and 800 V, respectively. The proposed method has been experimentally validated at different misalignment profiles while considering battery voltages 300-400 V and 600-800 V, which proves that the V/I -D converter is a universal charging solution for EV batteries.

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A variable switching frequency modulation for the Dual Active Bridge (DAB) converter is proposed in this paper. With this variable switching frequency modulation, the DAB converter can be operated in the ZVS-beneficial operational modes without the necessity to transition to others, thus a larger ZVS range for the DAB converter can be achieved. This modulation has potential of providing higher power efficiency and better EMI performance for the DAB converter in wide voltage range applications such as Electric Vehicle (EV) charging. A DAB converter with the variable frequency modulation method is simulated, and its effectiveness on the ZVS performance is demonstrated.

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Nowadays, inductive power transfer (IPT) with magnetic resonance is the most used method for high-power wireless battery charging applications. Once the topology of the compensation network and the operating frequency are selected, there are infinite combinations of the circuit equivalent inductance and compensation capacitance values resonating at that frequency. Choosing an appropriate ratio between these passive devices is essential to meet the target output power while ensuring that the required DC input and output voltages are found within the permitted range limited by the power source and the battery load. This paper proposes design trade-offs for selecting the optimum ratio between the inductance and capacitance in IPT systems with series-series compensation applicable to any power level. First, the target mutual inductance must be computed. Based on that, the coupled coils are designed depending on the physical constraints. An example is provided considering a 3.7 kW wireless charging system for electric vehicles (EVs) where different coils’ combinations are analyzed through the finite element method. The most suitable design is implemented, achieving or the application a relatively high measured peak DC-to-DC efficiency of about 96.24% at 3.28kW while the coils are aligned with 11cm distance. The required power is delivered at different battery voltages and coils’ alignments by regulating the DC input voltage.@en

An efficient, compact and lightweight three-phase AC-DC power factor correction (PFC) converter becomes a necessity for electric vehicles (EVs) On-board chargers (OBCs) in conventional grid-to-vehicle (G2V) and vehicle-to-grid (V2G) charging methods. The commercially available OBCs have very limited power density despite the moderate efficiency under specific power levels. In this paper, the integrated triangular current mode (iTCM) control is implemented to improve the power density (kW/L) and specific power (kW/kg) of the three-phase PFC converter stage while maintaining high efficiency. Zero voltage switching (ZVS) turn-on is realized in the iTCM control with a higher switching frequency to reduce the LCL filter size without sacrificing efficiency. By adding an LC branch between the bridge leg and mid-point of the DC link, the high-frequency and low-frequency currents are split to minimize the inductor loss and to derive a better inductor design. Analytical modeling and simulation in PLECS are conducted to verify the idea of iTCM. The capacitor-current feedback active damping method is implemented to prevent instability from the LC and LCL filters. The design of an 11kW three-phase AC-DC PFC converter, including the input LCL filter, achieves an efficiency of 98.81%, a power density of 12.46 kW/L and a specific power per weight of 1.87 kW/kg. The proposed three-phase iTCM control is benchmarked in a 3 kW SiC MOSFET-based AC-DC converter.@en

Two-stage AC-DC converters are considered as a prominent solution for DC-type electric vehicle (EV) chargers. However, this kind of architecture suffers from high switching losses with large heatsink and DC-link capacitor volume. To relieve this issue, this paper presents a new hybrid modulation for DC-type EV chargers, where a two-phase clamped discontinuous pulse-width-modulation (DPWM) in the front-end circuit is cooperated with the variable frequency triangular-current mode (TCM) zero voltage switching (ZVS) or its simplified implementation, i.e., boundary-ZVS (B-ZVS) strategy, in the back-end circuit. The former can stop the switching actions in the front-end stage during two-thirds of the grid period, while the AC currents are at their highest values, which can yield to the best switching loss reduction and deliver high power factor operation. Besides, TCM-ZVS or B-ZVS modulations can achieve ZVS turn-on action for all semiconductors during all operating range in the DC-DC stage to further reduce the power losses on the semiconductors. With such characteristics, the proposed strategies can reduce the switching losses of the system to the best extent, and thus allow an enhancement of the system power density by improving the power conversion efficiency. The proposed strategy is described, analyzed, validated, and benchmarked in a 5kW SMD SiC MOSFET-based two-stage AC-DC converter. A 99% power efficiency can be achieved with the solution implementing the TCM-ZVS strategy at an output voltage of 400V and rated power.

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Battery Energy Storage Systems typically procure their primary revenues from regulated energy and ancillary services markets; nonetheless, they have great potential in supporting distribution network operators and their users. This paper evaluates the potential business case of battery storage systems integrating market application and services to a photovoltaic assisted electric vehicle fast-charging station. A mathematical deterministic optimization problem is formulated using mixed-integer linear programming to combine battery storage system operation in the day-ahead and frequency regulation market and the remunerated services offered to the charging station. The technical and economic feasibility of the solution and the applicability of the proposed framework is verified through a case study reflecting an existing photovoltaic assisted charging station in the Netherlands and considering the Dutch energy market framework and prices. The study shows that such battery storage system implementation is economically and technically advantageous for the players involved. The battery storage system can stack additional revenues on top of the market revenues. The charging station benefits from a reduced peak power and a 30% tariff reduction, and the system operator would indirectly benefit from the shaved charging station profile. Furthermore, the analysis shows that providing services to the charging station from the battery storage system does not significantly impact its market-related revenues.@en