In this paper, a novel soft-switching-technique for quasi-single-stage$(\text{QS}^{2})$bidirectional DC-AC dual-active-bridge (DAB) converter is presented. The soft-switching-technique results in the triangular transformer current due to unsymmetrical switching of DC side H-bridge. DC side H-bridge of$\text{QS}^2$DAB consists of two branches, one branch supplied with fixed ON time pulse width modulation (PWM) signal. However, a variable ON-time controlled PWM is provided to another branch of the H-bridge. Due to this nature of switching, unsymmetrical H-bridge triangular modulation (TRM) is referred. The proposed modulation offered several advantages such as 1) near unit power factor correction (PFC) operation for bidirectional flow. 2) zero current switch (ZCS) turn ON and OFF for pulsating DC side H-bridge. 3) zero voltage switch (ZVS) turn ON and ZCS turn OFF for the switches of branch 2. 4) ZVS/ZCS turn ON for the switches of branch 1. 5) true soft-switching over the whole envelop of the line frequency. 6) improved performance with reduced total harmonics distortion (THD). A scale-down experimental prototype of 580 W is developed and the proposed technique is realized using TMS320F28335. A good power factor of 99.98% and THD of less than$< 2.71\%$with peak experimental efficiency of 95.7% achieved using the proposed modulation technique.

In this paper, the development of an efficient three- layer Cyber Physical System (CPS) using a multi-output power electronic interface integrated with IoT-enabled modules and AI- based algorithms is presented. The power electronic interface layer of the proposed CPS eliminates the need of bulky electrolytic capacitors and reduces the switching loss. This layer facilitates DC to DC and DC to three-phase AC power conversion for battery charging and smart-grid applications respectively. AI-based algorithms are utilized for accurately predicting the Remaining Useful Life (RUL) of batteries. The performance of the proposed CPS is validated through simulation and experimental measurement results using a 700 W prototype system. The measurement results show that the proposed CPS enables real-time monitoring, accurate prediction of RUL, predictive maintenance decisions, data analytics, and optimized power flow.

This paper proposes a novel fractional power processing (FPP) based solution for developing efficient ultra-fast charging (UFC) infrastructure for electric vehicles. The proposed strategy allows only a fraction of power to be processed through the converter, while rest of the power is bypassed through a series path from source to load. This improves the overall power conversion efficiency and reduces the current and voltage stress on the devices. In addition, the proposed FPP based architecture utilises the battery discharge voltage itself for charging of the battery, thus reducing the required DC voltage at the source. The operation of the converter is discussed and its advantages are mathematically established. A laboratory prototype of the proposed solution with current-fed resonant dual active bridge converter is developed and its steady-state behaviour is verified. Further, the performance of the proposed architecture is compared with the full rated converter through a 48 V battery charging, and the experimental results are presented.

Battery and super-capacitor-based hybrid energy storage systems (HESS) are becoming prevalent due to the dynamically varying power demand of electric vehicles (EVs) and dc loads. The boost-derived topologies used in these systems suffer from the problem of the Right Half Plane (RHP) zero in their voltage control plant transfer function. The RHP zero restricts the bandwidth and reduces the phase margin (PM) of the voltage control loop of the system. PM is further reduced with an increase in load or with a decrease in super-capacitor voltage. This causes ringings at DC-link voltage resulting in instability and restricting the optimum utilization of super-capacitors. This article presents a minimum phase converters-based hybrid energy storage system for dynamically varying DC loads and BLDC motors used in EVs. The proposed system eliminates the RHP zero, achieving high bandwidth with an enhanced phase margin. Therefore, the system's fast, smooth, and stable operation with increased phase margin and optimum utilization of the supercapacitor is achieved. MATLAB simulation results for the complete system are presented to validate the proposed system. Experimental results for the working of a minimum phase converter are also provided.

Grid integration of a transformerless interleaved hybrid converter (TLIHC) and its behavior during dynamic conditions for solar photovoltaic (PV) applications is proposed in this article. The controller design for the TLIHC and its dynamic performance is also discussed in this article. Further, the detailed analysis of grid side filter inductors$(L_{g1}$and$L_{g2})$and phase-locked loop (PLL) of the proposed TLIHC are discussed. Also, the closed loop control strategy of grid current$(I_{g})$is discussed in this article. As, the DC power processing part of the proposed TLIHC is a derived output form of a conventional boost converter, the performance of TLIHC is studied when both$I_{g}$and duty ratio (D) are varying. Further, the controlled switching pulses of the proposed TLIHC are well enough to minimize the high frequency common-mode voltage across the PV to ground parasitic capacitor. So, the harmful common mode leakage current is reduced in the system. In addition, as the shoot-through issue in the inverter part is resolved in this topology, the reliability of the proposed TLIHC is improved. Simulation results for the performance verifications of the grid integrated proposed TLIHC is also presented in this article.

Many modern appliances including Electric Vehicles use two batteries at two different voltages. Charging one battery from the other requires bidirectional DC-DC converter that charges the battery with lower state of charge. In addition to the converter, a charging algorithm is required for the optimal charge of the battery. There are three-existing optimal battery charging techniques; 1) constant current-constant voltage (CC-CV) charging, 2) pulse charging, and 3) reflex charging. However, these charging techniques require different control circuits for their implementation. Moreover, in the conventional chargers, the changeover from CC to CV is unsmooth as the circuit does not remain in the feedback control during the transition. To address the above issues, a fourth-order minimum-phase bidirectional DC-DC converter (BDC) with an adaptable feedback clamped modulator is proposed in this paper. The proposed charger is capable of adapting to all the three-existing charging techniques by controlling the clamping voltage. The steady-state behavior of the BDC is verified through a 250 W prototype. Also, the performance of the charger using CC-CV charging is experimentally verified using a 6 V- 4.5 Ah lead-acid battery.

This paper presents a unified loop based dual active bridge (DAB) with front end rectifier, a boost converter forming AC to DC power stage, and a DAB forming an isolated second DC-DC stage for electric vehicle battery charging application. In unified loop controller, controller capable of power factor correction (PFC) and battery charging control without sensing the DC link voltage in the topology is proposed. In this control strategy, irrespective of the nature of input supply (AC or DC) the output voltage/current maintained constant to the desired value as per battery constant current and constant voltage (CC-CV) characteristics thus the title referred mixed energy source. This type of power stage topology is used due to the inherent nature of the rectifier to provide DC output (constant or pulsating) irrespective of input supply nature. Therefore, a combination of unified loop and mentioned topology allows constant battery voltage/current irrespective of the nature of the input. A Boost converter is used to regulate DC link voltage depending upon load requirement thus varying DC link will allow to regulate the output supply of the DAB. As per the IEC 61000-3-2 standard, the total harmonic distortion in the current drawn from the AC main is restricted to prescribed limits. In this paper mathematical modeling of the topology has been carried along with a detailed study of working of the unified loop. MATLAB/Simulink based model along with the experimental results is discussed to support the idea with both AC and DC supply.

The leakage current is one of the major issues in transformerless PV inverters. It is essential to minimize the leakage current as low as possible. To achieve this, many topologies have been proposed based on different novel modulation techniques, novel circuit configurations. These topologies are predominantly voltage source inverters (VSIs) with discontinuous input current and have buck type characteristics. This paper presents a common ground based quasi-Z-source converter for PV applications. The leakage current is eliminated as the common mode voltage is zero due to the common ground. The proposed converter has continuous input current profile and gives buck-boost type AC output. MPPT operation can also be integrated with ease. The topology uses optimal number of switches as that of the conventional inverters proposed in the literature. The detailed operating principle and steady state analysis are discussed to show the advantages of the proposed inverter. Simulation results are provided to verify the operation of the proposed inverter.

Presence of right half plane zero (RHPZ) in conventional boost and buck-boost derived hybrid converters makes the system non minimum phase and it becomes difficult to obtain adequate phase margin along with higher bandwidth for such systems. Moreover, for microgrid applications, these need to operate on very high duty ratio in order to obtain high voltage gain, which causes severe reverse recovery of the diodes and increased EMIs. This paper introduces a high step-up hybrid inverter having no RHPZ for hybrid microgrid. The proposed hybrid inverter is developed by coupling the filter inductors of a quadratic boost converter with an insertion of damping network in the circuit and replacing the load side main switch by the H-bridge inverter. This arrangement helps in complete elimination of RHPZ and thereby makes the system minimum phase. The proposed hybrid inverter gives high step-up de voltage with comparatively low duty ratio and also provides simultaneous AC and DC outputs with inherent shoot through protection. Detailed mathematical modeling and small signal dynamic analysis are carried out. Experimental and simulation results are presented to validate the proposed hybrid inverter for the hybrid microgrid.

A high gain embedded dual switched capacitor boost-based impedance source DC-DC converter is presented in this paper. The converter is continuous input current based high gain converter which uses fewer passive components, lower capacitors voltage stress to achieve high voltage gain and inherits all the properties of impedance source network. This converter is suitable for batteries, photovoltaic, fuel cells for microgrid applications where the available input voltage is low and needs to step up by a huge value. The detailed analysis of operating principle and steady-state analysis are discussed to show the advantages of the proposed DC-DC converter. To verify the operation of the proposed converter, a hardware prototype is designed and implemented in the laboratory and the corresponding results are discussed in this paper.

This paper proposes a modified particle swarm optimization (MPSO) for fast convergence and harmonic minimization in three-phase eleven-level hybrid cascaded multilevel inverter (HC-MLI). Selective harmonic elimination pulsewidth modulation (SHE-PWM) technique implemented through MPSO has been used in the proposed work for synthesizing an eleven-level output voltage using two dc sources, a precharged capacitor, and twelve switches. The switching angles of the three-phase eleven-level HC-MLI has been computed for eliminating specified lower order odd harmonics such as 5th, 7th, 11th, and 13th from the output voltage of the HC-MLI. In the proposed MPSO optimized HC-MLI, capacitor voltage balance is also ensured even at higher modulation indices by utilizing the redundant switching states available at different switching instances of the HC-MLI. The performance of the MPSO optimized three-phase eleven-level HC-MLI has been verified through simulation and experimentation on a 1.5-kW prototype using closed-loop control. The results obtained through MPSO are compared with the results obtained through genetic algorithm (GA) and particle swarm optimization (PSO) in terms of convergence rate and harmonic content. It has been found that MPSO gives improved results in comparison to GA and PSO.

This paper proposes a digitally controlled bipolar converter for dc micro grids. The bipolar converter configuration is based on the combination of SEPIC and CUK converter with the modifications in both the converters. In the proposed bipolar converter, the equivalent series resistance (ESR) of the transfer floating capacitor is increased by inserting a series resistance in the both SEPIC and CUK converter and magnetically coupled inductors are used on both (input and output) sides of the SEPIC converter with damping network. Such type of arrangement eliminates right half zero (RHP) from the proposed bipolar converter and facilitates simpler controller design. The proposed bipolar converter is operated on field programmable gate array (FPGA) based digital current mode control for bipolar micro girds. The proposed concept facilitates regulated bipolar dc outputs and allows integration of renewable energy sources to bipolar micro grid. Thus, in view of the benefits of bipolar dc link, the proposed concept gives a solution to the requirement of distributed generation units with highly efficient, less costly and easy to implement. Detailed mathematical modeling and dynamic analysis is carried to take out the advantages of the proposed system. Simulation and experimental results are presented to verify the proposed algorithm.

In this paper, a minimum phase hybrid coupled inductor quadratic boost inverter (QBI) is proposed for DC microgrid applications. Microsources such as solar photovoltaic (PV), fuel cell, wind power, etc. are low voltage generation sources and to meet out the grid requirement a high voltage gain converter is required. Most of the hybrid boost and buck-boost drive inverters found in literature have a right half plane (RHP) zero problems (i.e. non-minimum phase system) and operating range limited to 0.5 duty cycle. With a non-minimum phase control-to-output transfer function, it is hard to obtain adequate phase margin and has bandwidth problems. In the proposed minimum phase hybrid coupled inductor QBI, filter inductors are magnetically coupled and a series damping network is inserted. With this arrangement right half plane (RHP) zero is eliminated for DC boost operation, and thus, the system becomes a minimum phase that provides better dynamic performance. The QBI is capable of giving high step-up voltage gain up to 16-17 times. The proposed minimum phase hybrid coupled inductor QBI provides simultaneous AC and DC outputs with inherent shoot through protection in the inverter stage unlike the conventional voltage source inverter (VSI). A modified pulse width modulation (PWM) technique is also presented for the proposed minimum phase hybrid coupled inductor QBI. The proposed PWM method reduces the stress on the switches and the switching losses of the inverter. Steady state and small signal dynamic modeling are carried out to exhibit the advantages of the proposed hybrid QBI. The concept is validated through simulation and experimental verifications.

A minimum phase PFC boost converter is proposed in this paper. The proposed PFC boost converter shows the minimum phase nature due to the complete removal of the right half plane zero (RHP) unlike the conventional PFC boost and boost derived converters. Due to the complete removal of the RHP zero the proposed minimum phase PFC boost converter is capable of supplying heavy load current requirement unlike the conventional boost PFC or boost derived PFC where load current is limited in the presence of RHP zero. The minimum phase nature of the proposed PFC boost converter makes the design of controller (for both voltage loop and current loop) simple. Detailed steady state and transient analysis is performed to show the merits of the proposed converter. Simulation and experimental results are shown to validate the proposed minimum phase PFC boost converter.

This paper presents a digital feedback-clamped synthetic ripple based hysteretic modulator for optimal battery charging. The proposed digital hysteretic modulator ensures a constant current (CC) charging for a low battery state of charge (SOC) and a constant voltage (CV) charging for battery SOC near 100 %. The modulator facilitates smooth and stable transition from CC to CV without the need of any extra switch or control loop. The proposed digital modulator generates carrier to the hysteretic comparator by generating piece-wise linear synthetic ripple using sensed converter voltages (switch node voltage and the output voltage), without the need of direct inductor current sensing and adding the output voltage to it. This facilities immediate (one switching cycle) fault detection incase of the main switch failure of the converter. A variable voltage feedback clamping circuit used in the proposed modulator makes the charging system feedback controlled in CC mode, in CV mode, and even during the transition from CC to CV. Experimental and simulation results verify the operation of the proposed charging system on 20 W prototype. The performance of the charger is verified on a 6 V-4.5 Ah lead acid battery as well.