With the rapid development of electrical vehicles (EV) and the trends in transportation electrification, the demand for fast charging facilities for electric vehicles is rising.

In this thesis, a two-stage power electronics converter for DC fast battery charging application is designed and studied. A buck type 12-pulse converter with triangular current shaping method for harmonic reduction and power factor correction is chosen to be the front-end converter. Back-end converter is designed to be a full bridge converter with partial power processing technique.

This thesis innovatively proposed highly efficient ultra-fast charger charger using the multiple pulses rectifier with partial power processing DC-DC converter.

This EV fast charger meets the requirements of isolation, high efficiency, high output voltage and good power quality (low THD and unity power factor). This thesis describes in detail the analytical modeling of the studied circuit, including {the} loss modeling of the semiconductors and passive components and the design of three phase three winding transformer and phase shift full bridge transformer. Finally, the simulation results and experimental results of the proposed EV fast charging system are presented and analyzed.

A High Voltage (HV) Modular Multilevel Converter (MMC) based Arbitrary Wave shape Generator (AWG) is to be designed for a final voltage of 100 kV with 67 submodules in each arm. They can be used to test unconventional stresses experienced by high voltage equipment. Before the realization of a full-scale prototype setup, it is necessary to validate the controller as it involves the complexity of communication and control of a large number of switches in the circuit while demanding accuracy in the generation of gate pulses. OPAL-RT was identified as a good solution for implementing the MMC control. This thesis intends to investigate two main objectives. Firstly, to evaluate the various capabilities of the OPAL-RT to implement control of MMC by performing simulations and testing it with real MMC with 12- submodules. Secondly, to design a PR controller for the MMC circuit and further validate it in real-time. The topology of MMC, as well as two modulation approaches – Phase-Shifted Carrier (PSC) and Nearest Level Control (NLC) were explored initially. This was followed by the filter design for 50 Hz and 1 kHz fundamental frequencies. Thereafter, the trade-offs for both control strategies based on the filter design requirement were examined. Furthermore, the various software tools included in OPAL-RT were investigated for potential use in the development of the control algorithm. To test the accuracy of gate pulses and the ability to generate precise waveforms for higher fundamental frequencies, Model-in-Loop testing with eFPGAsim is used. By realizing, the control algorithm in the CPU and the MMC in the FPGA, results obtained are compared with the offline simulations. It is observed that the minimum CPU time step is incapable of generating accurate waveforms for higher fundamental frequencies, resulting in missing or delayed gate pulses. Next, the control was implemented in the FPGA using internal PWM generators of the OPAL-RT and the MMC plant was tested both in the FPGA and as actual hardware. In PSC modulation, the phase shift between the upper and lower arm decides the switching pattern of the submodules, contributing to the building of the voltage level at any instant. In this case, the gate pulses’ phase difference between the lower and upper arms are noticed to be larger than what is observed from the offline simulations. These phase delays are resulting in the addition of delayed gate pulses at any instant causing strange switching voltage levels at the output, contributing to unexpected carrier harmonics. Furthermore, because the CPU samples the modulating signal before passing it to the FPGA for processing, it compensates for communication latency while also contributing to inaccuracy. Finally, a PR controller was designed and discretized for performing stability analysis, later implemented on the real-time setup. The PR controller resulted in suppressing the lower order harmonics by reducing them within the expected tolerance limits and the THD obtained was consistent with the results of the offline simulation.

Solar array fed water pumping system is a good approach for water management and agriculture purpose. PV panels highly depend on unpredictable environmental conditions, as a result, the development of a PV system is with more technical challenges. System-level simulation on a desktop computer has limitations, such as uncertain accuracy of the models, unable to test the system realtime behaviour and the communication and measurement of sensors that are required on physically implementing the system. On the other hand, implementing tests for a physical system has defects like high cost, unsafety and long development cycle. Therefore, based on the OPAL-RT real-time simulation platform OP4510, this project has implemented the real-time hardware-in-loop (HIL) simulation of the solar array fed water pumping system. In the meanwhile, the proposed HIL emulation system provides a virtual testing environment in the ESP Lab for solar panels, batteries or electrical machines.

The worldwide adoption of Electric Vehicles (EV) has gained momentum in recent years, with more than 30% of all EVs being sold last year. Additionally, a new trend of 800 V battery architectures has appeared to allow for faster charging than the now common 400 V architectures. Future proof charging topologies should, therefore, be able to provide a wide output voltage range. This study investigates how DC-DC resonant power converters can be employed to achieve a wide output voltage range of 150-1000 V for EV charging. After the literature study, a two-stage topology consisting of a LLC converter and Interleaved TCM Buck converter is selected for this purpose. Additionally, the competitiveness of an IGBT based solution is examined in comparison with a SiC MOSFET based solution. An analytical model is created in MATLAB and verified using LTSpice, after which different configurations of the 11kW two-stage converter are compared analytically. This comparison is performed by developing a method to assess the efficiency of a converter based on real-world Charging cycles. A trade-off is made between efficiency and costs. In the end, one stage is equipped with IGBTs in the final design. After this, a PCB is designed and used to implement the prototype of the final design. The analytical and simulation models are verified experimentally using the prototype. 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 obtained efficiency for the 11 kW-400 V Charging cycle is 96.85% and 95.67% for the 11 kW-800 V Charging cycle. The proposed converter in this study thus proves to be a highly efficient charging solution that is capable of charging existing, and future Electric Vehicles.

The usage of physical space in an Electrical vehicle is a roadblock to achieving peak performance in wireless charging applications. Components like the receiver, onboard power electronics, etc. have to be arranged in such a way that challenges like bulkiness, power density, thermal management is handled to achieve maximum operating life of these devices and their performance. This becomes more prevalent in heavier vehicles. This thesis explores such possibility of solving this constraint by placing the power electronics on top of the receiver.To start with, different frequency ranges used in Wireless power transmission are discussed, fol­lowed by topologies of the coil and compensation networks. Every topology and network has its ad­vantages and disadvantages. And based on various parameters, a comparison is made.Subsequently, power losses across various components of both the primary and the secondary sides of the Wireless Power Transmission(WPT) are calculated in their worst ­case scenarios. These losses are essential for analyzing the thermal management of the system, as these losses produced by the devices generate heat.A series of thermal models were designed on COMSOL 5.6a to analyze the temperature distributions of these circuits. Starting with a simple model which involves two diodes connected in series to more complex cases like the design of the receiver and finally to the last step which is placing the rectifier on a heatsink atop the receiver. The results are experimentally verified and many conclusions are deduced from them. These results give a better understanding of how heat flows in a system. A Thermal analytical model is designed on LT­-SPICE to a thermal circuit of arrangement of the components in the system.

The need for efficient power transfer at lower cost is a common requisite for any power con­verter system. When considering the application of wireless power transfer for Electric Vehicle(EV) charging, higher efficiency and lower cost can be achieved by reducing the number of stages of the system at the grid side. This thesis explores the feasibility of an AC/AC matrix converter for wireless power transfer application. To begin with, different existing topologies of the converter module are discussed and qualita­tively compared to the matrix converter. Subsequently, the plausibility of single stage matrix converter is verified through simulation. Due to the converter’s high switching frequency, this configuration results in injection of higher than permitted harmonic content into the grid. Fur­thermore, the feasibility of three phase matrix converter and its advantages are studied. The converter working is verified through simulation. To make the grid current less distorted, closed­ loop control is introduced. This control con­sists of an inner current loop and an outer voltage loop which are both implemented using a PI controller. To conclude, three phase matrix converter acts as a plausible solution for the desired applica­tion. Furthermore, the control ensures balanced grid current and desired output power.

Up to 5 kW PV installations microinverters are common alternatives for the typical string solar inverters. The main draw back of the technology is the slight higher initial cost, however, a more efficient energy generation can be achieved if one of the PV modules are operated optimally at the maximum power point. This work shows that converters employed using low voltage Si-MOSFETS can exhibit excellent loss performance. Power efficiency above 97 % is possible yielding to much lower total cost of ownership. This thesis emphasizes on the investigation of microinverter technology in residential PV systems. A small scale prototype is developed to evaluate the performance of the selected topology. The advantage of the designed circuit are flexibility in expanding the system, redundant switching states and, less number of semiconductor switches per PV module.

The phenomenon of phase unbalance is prevalent in the low voltage distribution grid due to the presence of single-phase loads. The unbalance can cause issues such as capacity underutilisation, transformer losses and problems with induction motors. To ensure the reliability of the upstream grid, it is important to maintain balanced three-phase power. This becomes more relevant with the proliferation of Distributed Energy Resources (DERs) and storage. This thesis explores the use of power electronic devices as a power redistributor.
To begin with, different topologies of a converter are discussed. These topologies have their own sets of advantages and disadvantages. Based on various operating and design parameters, a comparison between these topologies is made.
Subsequently, different control strategies for the converter are analysed. Among these, the current control strategy ensures supply of balanced and sinusoidal current to the loads with low computational burden, and is hence chosen. This strategy involves the control of sequence components independently in the double synchronous reference frame.
Low-frequency harmonics occur in the DC-link as a result of the compensation of negative-and zero-sequence components by the converter. The magnitude of this low-frequency harmonic and the overall harmonic Root Mean Square (RMS) current in the DC-link are derived mathematically and validated by simulations to represent this converter. It is observed that the DC-link sizing is mainly dependent on the low-frequency harmonics and thus, their accurate estimation will help in better sizing of the DC-side components.
The various configurations of the converter under consideration are benchmarked against each other on parameters such as Total Harmonic Distortion (THD), Power Losses, and DC-Link Sizing.

TU Delft and KEMA laboratories are collaborating to create a Programmable high voltage test source by employing Modular Multilevel Converter MMC which can generate output voltage waveforms of any arbitrary shape. To produce an Impulse waveform of magnitude 250 kV across a capacitive load of 10 nF with a rise time of 1.2 µs as output voltage, each Power Electronic device incorporated into each Sub-Module of the MMC has to conduct pulse currents as high as 850 Amperes. Moreover, the Impulse Waveform has a very short time duration. Hence the Power Electronic devices need to conduct such high current magnitude only for a very short duration of time. This motivates this Master thesis to find out how many multiples of its rated current a Power Electronic device is able to conduct within such short time and what factor limits the peak current capability of the Power Electronic device. However, to produce an output voltage of any other waveshape each Power Electronic device of each Sub-Module of the MMC has to conduct only a few amperes of continuous current. Employing Power Electronic devices of current rating as high as pulse currents of Impulse waveform is not only uneconomical since other waveforms do not require such high continuous currents, but also such Power Electronic devices of high current rating would make the MMC bulkier.
To identify the Power Electronic device technology that is capable of conducting such high pulse currents, a literature review is conducted among IGBT, MOSFET and their types. Each device of IGBT and MOSFET is compared to one another. Finally, the most promising switching technology is chosen among MOSFET and IGBT based on three criteria namely, high peak current capability, high voltage blocking capability and high switching frequency.
A prototype of Pulse Current Test circuit is built to test the peak pulse current of the chosen switching technology. Then, the factors that can be utilized to achieve the peak pulse current are identified. Based on results of the pulse current test, the multiplication factor of the rated current of the Power Electronic device is identified. Switch technology for the MMC specifically for Impulse waveform is suggested.

This project investigates the newly proposed Belgian Rectifier, a novel three-phase boost power factor correction rectifier which is advantageous for AC-to-DC conversion in applications, such as, off-board and on-board chargers for electric vehicles. The Belgian rectifier can achieve very high levels of efficiency
and power density, while its components endure much lower stress than in other rectifier topologies.
The capacitive midpoint produces a three-level voltage over the switches and inductors, therefore a number of advantages can be pointed out such as low stress of the MOSFETs, low magnetic energy requirement for the inductors and low EMI filtering. Two modulation schemes have been analyzed with regard to component stresses and soft switching and one of them is proposed. The modulation scheme derivation is followed by a full analysis of the converter that consists of steady-state modelling, dynamic closed-loop modelling, component loss and volume modelling. In addition, by sweeping through different
parameters in the aforementioned models, a Pareto-front in the efficiency versus power density performance space is created. Thereby, an optimal design can be picked out using multi-objective optimization. Finally, a comparison between the Belgian Rectifier and Six-Switch Rectifier is done to reveal the advantages and disadvantages of the former topology.

In the past years electric cars have been rapidly taking market share in the automotive industry. Stimulated by their sustainable image and due to large investments in the charging infrastructure, the electric automobile has gained popularity in the field of research. Many papers are written on a variety of power converters inside the cars to interface between batteries, chargers and motors. Usually, these converters are made as universal as possible, in order to suit the needs of many different vehicles. As a result, they are capable of operating at wide voltage and power ranges, often at the cost of weight or efficiency. The Dutch electric car startup Lightyear aims at a completely different strategy. Their car with integrated solar panels is designed with one goal: increasing efficiency. For that reason, all components have been reconsidered and, if sufficient gains in efficiency can be achieved, completely redesigned. One of these components is an isolated bidirectional DC-DC converter that ensures power transfer from the solar panels to the main battery. In this thesis that DC-DC converter is developed. Special focus is put on maximizing the efficiency to ensure as much energy from the solar panels can be used to power the car. First, all possible topologies that meet the requirements are investigated and the best option is selected. Then, a script is developed that configures the power stage of the converter using a provided list of components. The implementation with the highest average efficiency over the operating range is automatically selected. After that, alternative modulation strategies are investigated, aimed at reducing the conduction losses of the converter. Finally, a controller is created and validated for the designed converter. The result of the presented work is an isolated bidirectional DC-DC converter, achieving an average power stage efficiency of 98.1 % over a wide range of input voltages and output voltages at a constant power output.

The parallel connection of a Silicon (Si)-based IGBT and a Silicon Carbide (SiC)-based MOSFET forming a so called hybrid switch can be used to capitalize on the advantageous features of both semiconductor and materials technologies. In this thesis, a hybrid switch-based inverter designed for the application of Electric Vehicle (EV) traction drive is compared to the conventional inverter assembled with Si-based IGBTs, and SiC-based MOSFETs. According to different standardized driving cycles, Electric Vehicles operate in low partial load for a considerable amount of the time. Therefore, in this application, semiconductor conduction losses can be considerably reduced when unipolar switches such as MOSFETs are used. Collectively, this work shows that the hybrid switch configuration constitutes a good compromise between efficiency and cost when compared to a solution implementing only Si-based IGBT or solely SiC-based MOSFETs.

Fast charging technology has accelerated the growth of the electric vehicle(EV) market and attracted significant attention from the industry. Two-stage AC/DC converter system is one of the traditional fast-charging architectures consists of the front-end converter and back-end converter. Numerous researches have developed IGBT-based medium-voltage converter or MOSFET-based low-voltage applications. In this work, a two-stage IGBT-based converter system is proposed in consideration of power switch costs and magnetic component loss.

The power system in Northern Europe supports a high degree of penetration of Wind Energy-based HVDC connections. Most of the modern HVDC connections will have Bipole with a dedicated metallic return (DMR) configuration. This thesis presents a basic guideline to increase the Levelized cost of operation of Bipole HVDC links by attaching the offshore poles to the point of common coupling and designing suitable control strategies. The results show that the control strategies can be applied under various real-life scenarios with slight overvoltages within the acceptable range.

Over the last decade the share of electric vehicles has increased and will continue to increase in the future in order to reduce the carbon footprint by transportation. However, the battery voltage is not standardised and can differ per car model. To reduce the charging time, a high power converter is preferred. Moreover, in order to utilise the car as a storage element and enable the Vehicle to Grid functionality, the capability of a bidirectional power flow is needed.

In this master thesis a DC-DC converter is designed for a wide output voltage range, with the focus on a high efficiency. Firstly a literature review is done, where the Dual Active Bridge (DAB) converter is chosen as a promising topology. The rectangular (single phase shift), triangular and trapezoidal current modulation are all investigated. For the actual design, two types of transistors are considered, followed by the design of a transformer and inductor. In the end a prototype according to the design is made and the modulation method is implemented in a digital controller.

Wireless power transfer (WPT) is becoming a popular choice for charging of batteries in various applications. Particularly, the increase in popularity of electrical vehicles (EVs) and the pursuit of user convenience for charging the batteries makes WPT an attractive solution. The usage of WPT in e-transportation is not straightforward because the current standardization limits the allowed frequency operating range and magnitude of the irradiated magnetic field. Additionally, a fast control loop with high current or voltage sensing bandwidth is necessary to guarantee soft-switching of the inverter’s semiconductors which are commonly employed as part of an equivalent DC-DC resonant converter. The resonant circuit typically comprises of a H-bridge inverter, two passive compensation network one at each side of the air-gapped transformer formed by a transmitter and a receiver coil, and a diode-bridge rectifier. The control of the resonant converter can be cumbersome particularly in case of dynamic charging condition because of the natural change in equivalent load and coil misalignment conditions which cause themagnetic coupling to change. The main goals of this thesis are: to understand the challenges involved with the control of WPT for EVs; to propose and implement a digital control strategy for WPTs which not only maintain soft-switching but also realize other functionalities such as soft start-up, soft shut-down and over-current protection. With respect to power efficiency, it is important to operate the inverter with a frequency whichmakes the resonant converter to function in the inductive region enabling soft-switching turn-on of the implemented active semiconductors, such as MOSFETs. For that reason the inverter is typically operated at a frequency slightly above the resonance, however this must avoid the effect of bifurcation. Studies in the literature have found that the efficiency of the system is typically the highest at maximal magnetic coupling between the coils and when the resonant circuit impedance match the so-called optimal load resistance. Furthermore, the current available standards have set narrow requirements on the frequency range, minimum power efficiency and restriction of irradiated magnetic field for both, safety of living beings and electromagnetic compatibility. All these requirements makes the control implementation of WPT very challenging, especially for high power applications. In this work, the closed-loop control is successfully integrated into a TI microcontroller where the soft-switching mechanism is derived with a selective band zero crossing detection circuit of the inverter AC current. The current band is used to tune the instant where the semiconductor bridge turns from ON to OFF state because there is a minimal current that need to be impressed into the inverter to reach the desired soft-switching by compensating the accumulated charges across the parasitic MOSFET capacitances. This is also important to compensate the signal processing delays of the closed-loop control. This functional block is implemented externally to the TI digital controller with the existing high bandwidth current sensing and commercial analog logic ICs. Moreover, an over-current protection is incorporated into the zero crossing block, achieving a reaction time of 66ns. Finally, several strategies are proposed and tested for the soft start-up and a concept is made for the soft shut-down of aWPT experimental setup available in the laboratory.

The Electric Vehicle (EV) charging market is very dynamic. The so-called AC-type chargers can be found confined within the vehicle or on-board. This must be able to withstand the harsh environment with an ambient temperature of above 75℃. Therefore, compact and high-efficiency power electronics and implementing electrolytic-less capacitors in the power range of 6 kW to 12 kW is desired. The operation of the grid-connected power stage with DC active power buffer has become standard in high compact systems. More importantly, this solution eliminates the requirement of high energy storage in the DC-link because the pulsating power is compensated leading to an electrolytic-less capacitor design. As the lifetime of the power converter in high-temperature environments is typically limited by the usage of the electrolytic capacitor technology, a more reliable system is finally obtained with the active pulsating power buffer.

The last ten years with the entrance of the SiC devices at the power electronics industry, new fundamental requirements have emerged. New types of gate drivers need to be developed due to the need for creating two voltage levels for driving the SiC based power switches efficiently; one positive and one negative bias voltage. Besides this requirement, extra measures need to be taken for the proper operation of the driver and its sufficient protection. The electromagnetic interference is increased compared with the conventional silicon based applications, which potentially can cause malfunction or disruption at the operation of the gate driver. Furthermore, ultra-fast response in case of faults must be designed, because of the lower fault capability of the new devices. Sophisticated methods are employed with the measurement of di/dt being one of them. This work focuses on proposing, designing, and testing of a robust gate driver capable of detecting and isolating in less than 1 μs a short-circuit of a power module. It uses the PCB principle embedded Rogowski coil so that the gate driver control can re-build a voltage signal, which is an image of the current flowing through the upper and bottom active switches. Finally, a comparison band logic interrupts the gate ON signal when the current reaches a prohibitive level. Simulation and experimental tests are used to verify the advantages of the proposed gate driver.

Until recent times, electrical power grids have been dominated by conventional power plants run by fossil or nuclear fuels in order to cater to the electrical load demand. These power plants employ large generators that operate in synchronous with each other to maintain a stable frequency and voltage across the power grid. The frequency and voltage stability, which are respectively linked to active and reactive power serves as a backbone for a secure operation of the power system. Furthermore, since these classical generation sources promised support of ancillary services during unstable conditions, along with power generation, they were characterized as a reliable solution for maintaining the security of the power system. But, due to the high emission of carbon by-products from these fossil-fuelled generators, challenges of global warming and climate change have made it inevitable to decommission them. And more emphasis has been embarked on the adaptation of renewable energy sources (RES) which offer minimum carbon footprint. Geothermal heat, wind, sunlight, and tides constitute some of the Renewable energy sources since their availability are unlimited and involve the least emission of greenhouse gasses, hence Renewable Energy Sources have a minimal impact on the environment compared to traditional energy sources and can effectively tackle the problems which arise with fossil fuel usage. For all these reasons, during the last decades, there is fierce research on finding ways to produce the needed energy in a sustainable fashion. Synchronous Generators, which are dominant in the existing power grid, have the inherent characteristics to relate system’s frequency with load balance. This considerable advantage is found missing from Power Electronic interfaced renewable energy resources due to the following reasons. Firstly, since active power support was earlier the main purpose of using these devices, they were operated at Maximum power point tracking (MPPT). Secondly, in wind energy technology, isolation between electrical and mechanical circuits had to be introduced due to their variable behavior of energy production, and this has led to no inertia backing from the synthetically produced frequency. So with high penetration of RES in the future grids, the aforementioned problems pose huge risks for grid stability and reliability. The current research mainly focuses on the development, implementation, testing, and validation of frequency regulation strategies under the umbrella of Fast Active Power Regulation controllers specifically to support during large load frequency variation in low inertia power system grid. These controllers developed are very generic and can be implemented with slight modifications in all the renewable energy devices with ease. In order to simulate more real-time behavioral conditions, dynamic simulation studies are performed in RSCAD software interfaced with a Real-Time Digital Simulator (RTDS). Two Test benches have been considered in this thesis, one being an IEEE 9 bus system modified with 52% wind share and another is the North of Netherlands Network. In the first stage of the project, FAPR controller’s proof of concept has been tested on a Type-4 Wind generator setup connected to the modified IEEE 9 bus system. Here wind penetration is scaled up to 52% and a low inertia grid have been simulated. Later, the results obtained here were validated by Hardware in Loop setup utilizing a mock-up grid side converter. The next stage of the project aims at making FAPR controllers more generic. For this the North of Netherlands network was modified by adding FAPR integrated 300MW solar farm, FAPR integrated 82MW full converter based Type-4 Wind Turbine and lastly, a responsive load (Electrolyser) was modified to accommodate FAPR controllers. All together formed a Multi-Energy Hub and simulations were performed to check the practical feasibility and boundaries of operation of FAPR controllers in the future power grid. The results prove that the proposed topology and control strategies can effectively provide frequency ancillary services to the grid by providing support during dynamic load frequency variations.

Recent studies have shown that energy distribution systems based on hybrid (or parallel)point-to-point AC and DC links are interesting solutions for capacity enhancement andon-line improvement of energy efficiency under specific operating conditions, particularlyfor high power, medium to high voltage levels and long-enough distances, e.g.>5km.Additionally, due to the power controlability provided by the power electronic circuitswithin the DC links the parallel distribution system can be re-configured through GISdisconnectors operating with improved switching performance. In this work this featureis explored and strategies for the system re-configurations are proposed. These aim toprovide a nearly zero current switching for the GIS in order to prevent its deteriorationand to extend the number of maneuvers for the typical GIS lifetime.
In fact, the proposed re-configuration strategies rely on the DC bus voltage and powercontrols of a Back-to-Back (B2B) power electronic system constructed with Voltage SourceConverters (VSC). Herein, three-wire three-phase two-level VSCs with thrid-order AC har-monic filters (or LCL filter) are adopted in the B2B system. Moreover, Grid-side CurrentControls (GCC) for the inner/fast control loops of the front- and back-end circuits are im-plemented in order to enhance the system performance against grid disturbances. Herein,a notch filter-based GCC scheme with a harmonic rejection control is proposed. This isable to deliver attenuation to the LCL filter resonances while suppressing the harmonicsin the grid-side currents originated when the AC voltages are distorted. Interestingly,the parallel AC and DC links provides a low impedance path for the zero-sequence com-ponents which can be created by the power electronics, thus the implementation of aZero-sequence Circulating Current (ZSCC) controller becomes necessary for the properoperation of the system. Hence, ZSCC controllers for the VSCs are used, while bothfront- and back-end circuits are modulated with constant switching frequency using theconventional sinusoidal PWM strategy.
All in all, results are obtained in both, computational simulations carried out in MAT-LAB/SIMULINK and laboratory experiments performed in a5kVA VSC or a B2B circuit,are used to verify the study and to prove the superior performance of the investigatedand proposed technical concepts. Herein, more specifically for the re-configuration studyof the parallel AC and DC links, the standalone mode control of the receiving-end VSCin the full DC link configuration is investigated and the smooth transition between grid-connected and standalone modes are realized in both simulation and experimental tests.