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Bidirectional dc-dc converter (BDC) is an integral part of energy storage interface, where high efficiency, high voltage transfer ratio and small input ripple current are essential for application, such as dc microgrid and electric vehicle. In this article, a new approach is proposed to achieve reduced input ripple current at the low voltage side, which potentially replaces the necessity of using interleaved circuit structure. Parallel coupled inductor and capacitor circuit are utilized for charging and discharging the two parallel paths in a complementary fashion using a mosfet. The proposed solution helps to increase the voltage conversion ratio unlike interleaved structure. Additionally, in proposed BDC, zero voltage switching turn on operation of all active switches are possible utilizing synchronous rectification principle in both the operating modes. Parallel path structure not only reduce the input current ripple, but also helps to share the input current, thereby reducing the coil size and associated losses. A 250 W BDC is designed to validate performance in 1kW dc microgrid system

Today, transformerless inverters (TIs) are widely applicable in different solar photovoltaic (PV) grid-connected applications owing to their promising features, such as higher efficiency and power density. However, high-frequency common-mode voltage (CMV) in these topologies can result in high leakage current, electromagnetic interference, and lack of safety, reducing the whole system’s reliability. To resolve the problems associated with TIs, this paper proposes a novel hybrid switched capacitor (SC)-based common-ground (CG) transformerless inverter (TI) topology, which can be applied in grid-connected photovoltaic (PV) applications. The boost inductor is integrated to achieve continuous input current and dynamic voltage gain. In addition, the proposed circuit comprises nine switches and two SCs with a single input DC source. It can generate five-level AC voltage with voltage boosting within a single-stage DC–AC power conversion. The working principles of the proposed topology, circuit description, and control technique are presented. Furthermore, the proposed inverter is comprehensively compared with other five-level TIs to show its superiority. Finally, a laboratory prototype is developed and tested to validate the practical viability of the proposed configuration.

Single-phase buck-boost inverters are very popular nowadays due to the wide input voltage range regulation capability. This feature is mostly demanded by photovoltaic (PV), fuel cell, or battery storage applications. In this study, four new structures from the family of flying inductor (FI)-based inverters are presented. Performance in a wide range of input dc voltages and the ability to increase the voltage in single-power processing stage is one of the features of the proposed structures. Three of the four structures are common ground and completely bypass the parasitic capacitors which make them attractive for PV application. Nonuse of electrolytic capacitors in the proposed structures helps to increase the life of the converter and also there is no unpleasant inrush current of charging electrolytic capacitors in these structures. The operation modes are fully explained, as well as the theoretical analysis and design of passive elements have been done. Finally, the simulation and 2 kW laboratory circuit for the proposed Type-III structure are performed and the results are investigated.

This article presents a new nonisolated three-port converter with reduced component count compared with existing reported topologies. This is achieved by developing different power flow graphs and selecting the most appropriate converters arrangement. In addition, as compared to only one bidirectional port in most reported studies, this article considers two bidirectional ports to accommodate applications requiring bidirectional power flow, such as dc microgrid and regenerative braking. The proposed converter is able to work in seven different modes of operation, which cover all possible combinations of power flow among the three ports. Furthermore, seamless and smooth transition, maximum power point tracking, battery protection and output voltage regulation are achieved. Experimental waveforms, particularly for transient responses during mode transition, are reported to verify the proposed TPC.

This paper proposes a universal converter that is capable of operating in three modes for generating positive dc voltage, negative dc voltage, and sinusoidal ac voltage. By controlling the duty-cycle of two half-bridges, an inductor is operated at a high frequency to control the voltage across two film capacitors that constitute a dual-buck-boost converter. Two additional half-bridges operating at a fixed state or line frequency are used to select the mode of operation. Compared to the latest universal converter in the recent literature, the proposed topology has the same switch count while reducing the number of conducting switches for inductor current and reducing the number of switches operating at high frequency. The operation of the proposed dual-buck-boost dc–dc/ac universal converter is analyzed. Experimental results are presented for validation. The power conversion efficiency of the 100 W experimental prototype modeled in PLECS is approximately 98%.

This paper proposes a novel 5-level active neutral-point-clamped (ANPC) inverter that doubles the voltage gain of the conventional topology from half to unity. Each phase of the proposed topology is constituted by three half-bridges that control a flying capacitor to generate 5 symmetrical ac voltage levels. Natural voltage balancing of dc-link and flying capacitors in the proposed topology implies that the sensors and voltage balancing controller commonly used in the conventional ANPC inverter is no longer necessary. In addition to switch count reduction, the most noteworthy merit of the proposed topology is its ease of implementation with commercial half-bridge modules, where the design of dedicated circuit is not needed. The operation of the proposed 5-level unity-gain ANPC (5L-VG-ANPC) inverter is analyzed and validated through simulation and experimental tests.

Common-ground (CG) string inverters with a transformerless (TL) circuit configuration have been broadly popular in grid-connected photovoltaic (PV) applications. The most important feature of a PV string TL inverter with a CG circuit connection is the elimination of leakage current concerns. Having the voltage boosting property within a single power processing stage can also be propitious to further facilitate the integration of low-scale PV string panels with higher efficiency. An efficient topology of such converters is presented in this study, which is able to produce a five-level stair-case output voltage waveform using an integrated switched-boost (SB) cell with only seven power switches. The proposed SB common grounded five-level (SBCG5L)-TL inverter can also be extended for the three-phase CG-based applications with the contribution of the same integrated SB cell. As for the single-phase configuration, it needs two dc-link capacitors and two power diodes along with two small inductors. A quasi-soft charging operation of the involved capacitors is also achieved. To control the injected current under the grid-connected condition, a single-step model predictive control (MPC) technique with a fixed switching frequency operation has also been presented. The proposed circuit description, the theoretical analysis of the applied MPC principles, and the comparative study with associated experimental results are also presented to ascertain the correctness and feasibility of the proposed SBCG5L-TL inverter.

Single-inductor multi-input single-output (SI-MISO) switching DC-DC power converter architecture is a cost effective solution to applications where multiple input sources are required to be managed with a limited space and cost. This paper presents a new time-multiplexed hysteretic control (TMHC) scheme for SI-DISO topology to decouple the power sharing among two input sources. Unlike previously reported solutions with discontinuous conduction or pseudo-continuous conduction operation of the inductor, this paper focuses on how to keep the inductor current in a continuous conduction mode (CCM) and proposed a control scheme with considerably lower ripple current with fast transition time upon switching and higher efficiency. The mathematical proof using the expressions of inductor ripple current, comparison between efficiency and transition time from one level to other, is derived. Additionally, a low-cost analog circuitry has been implemented to incorporate the proposed control scheme. Experimental results from the hardware prototype are given to verify the proposed control scheme.

H-bridge inverter is a common topology used for single-phase applications. Due to its limited voltage gain, a two-stage power conversion with a front-end dc-dc converter is usually adopted to accommodate the low dc source voltage. Recently, single-stage boost inverters are gaining significant interest due to their higher power efficiency and compactness. This paper presents a family of boost inverters with continuous dc source current. By the incorporation of merely a power switch and a boost inductor to the first leg of H-bridge, voltage-boosting and 3-level generation can be simultaneously achieved within a single-stage operation. All potential topologies using the same number of components are derived. An extension to generate five voltage levels with voltage gain enhancement is also proposed. The operation of the proposed boost inverters is thoroughly analyzed. Simulation and experimental results are presented for verification.

The merit of switched-capacitors-based multilevel inverters (SCMLIs) is generally quantified in terms of a 'cost function' (CF) that incorporates parameters such as voltage gain, component count, total standing voltage (TSV), and number of levels. In this article, a 13-level inverter is proposed with the aim of achieving a low value of CF. The proposed single-stage SCMLI uses one input source and three capacitors to attain a voltage gain of 3. It requires 13 power switches, of which the peak inverse voltage (PIV) of nine switches is restricted to the source voltage. The remaining four switches have PIV equal to twice the source voltage and they operate at low frequency. Thus, for all switches, the PIV is less than the amplitude of the output voltage. Moreover, the capacitors are self-balanced at all regions of modulation index values. The proposed inverter is validated through simulation and experimental results. A comparison of the proposed topology with other contemporary SCMLIs shows that it is highly competent in terms of CF, PIV and TSV requirements, waveform resolution, and capability to achieve voltage balancing of capacitors at low values of modulation index.

This paper proposes two improved cascaded H‐bridge (ICHB) multilevel inverters that feature voltage‐boosting capability. The conventional H‐bridge with a front‐end dc–dc boost converter was restructured for single‐stage operation. The developed three‐level topology not only saves one power switch but also exhibits lower voltage stress across its capacitor. Extension to five-level generation was also introduced by merely adding two power switches and one capacitor. The final five‐level topology outperforms the classical cascaded H‐bridge (CHB) multilevel inverter with a significant reduction in the power switch count, with a 42% and 50% reduction in both the isolated dc source and inductor counts. The power efficiency was also improved without compromising the modularity feature of the classical CHB multilevel inverter. The operation and theoretical analysis of the proposed topologies were validated via simulations and experimental tests.

Single-stage inverters with a common ac and de ground are emerging topologies which effectively eliminate the high-frequency common mode voltage. However, most of the existing common-ground-type inverters are based on switched-capacitor (SC) circuits which are inherently subjected to several important issues that lead to many practical limitations. Disadvantages such as high current spikes, high capacitor voltage ripples, and distorted ac output voltage with de offset are some significant challenges in these inverters. A new common-ground-type inverter that discard the use of SCs is therefore proposed in this paper. It consists of a single-inductor and an ac output capacitor that are controlled by 8 power switches. Sinusoidal ac voltage generation in both buck and boost modes can be achieved by controlling the inductor with a sinusoidal duty-cycle. Simulations are presented to verify the operation of the proposed topology.

The emerging active-neutral-point-clamped (ANPC) inverters with voltage-boosting capability are attractive for their low dc-link voltage requirement. These low voltage requirements enable a single-stage dc-ac power conversion, which improves the overall efficiency, reliability, and power density of the system. A high voltage gain of 1.5 was demonstrated in recent boost type ANPC topology; however, it was achieved at the expense of high voltage stress on some of its switching devices. This brief proposes an improved topology with reduced voltage stress and a lower number of components while retaining the merits of high voltage gain. The proposed topology is a hybrid of a T-type inverter and an H-bridge, which require only one floating capacitor and one less power switch than the aforementioned topology. One floating capacitor with self-voltage balancing capability is integrated to generate 7 output voltage levels. The proposed topology is analyzed and compared with recent boost ANPC topologies. Experimental results are presented for validation.

A single-phase transformerless mid-point clamped H-bridge zero-voltage switch-controlled rectifier inverter topology is proposed in this paper for photovoltaic (PV) systems to address the issue of common mode (CM) voltage and leakage currents. Apart from the full H-bridge inverter, the proposed voltage clamping circuit consists of two switches and a full-bridge diode which clamps the AC terminal to the DC midpoint (consisting of two DC-link capacitors) during the freewheeling period. As a result, the common mode voltage is held constant which makes it suitable for the grid-connected PV system. The operating principle and CM effect of the proposed topology are analysed and compared with the conventional topologies. This is followed by the thermal analysis and loss calculation, which shows that the proposed circuit is more efficient over the conventional topologies. Validation is carried out using MATLAB-Simulink using the PLECS toolbox followed by a scale down prototype of 1.5 kW. It is shown that the proposed inverter has the 98±1% efficiency over a wide range of loads with a peak efficiency of 98.96%, and the total harmonic distortion of the output current relatively low (≤1.8 %). The leakage current (icm) is measured for different values of parasitic capacitance that reaches a maximum of 16.65 mA for 330 nF capacitor under consideration which is well below the limit set by different safety standards

© 2019 IEEE. The active neutral-point-clamped (ANPC) inverter is a popular multilevel inverter for various industry applications. In a recent attempt, an improved topology that integrates a flying capacitor to enhance the voltage gain from half to unity has been presented [11]. Retaining the benefit of unity-gain, this paper proposes a new ANPC topology with two improvements. Firstly, the voltage stress of the flying capacitor is reduced by half. Secondly, the charging of the flying capacitor at 0 level is made possible to achieve uniform charging over the power cycle. Comprehensive analysis is presented and experimental results of a prototype are presented for validation. Finally, the extension of the topology with increased number of output voltage levels generation is briefly discussed.

© 2019 IEEE. This paper presents a new transformerless inverter topology which is termed as a single-stage common-ground boost inverter (S2CGBI) for single-phase solar photovoltaic (PV) systems. The proposed topology provides a common-ground for both the dc source and ac output to eliminate the leakage current induced by the parasitic capacitance of PV cells. Voltage-boosting is made possible with the incorporation of only one inductor, which renders the realization of single-stage power conversion. The proposed pulse width modulation (PWM) technique is capable of charging the inductor with a constant duty-cycle while guaranteeing ac output generation. The operation of the proposed S2CGBI is analyzed. Simulation and experimental results are provided to validate the effectiveness of the proposed topology and modulation scheme.

© 2013 IEEE. This paper proposes a modified coupled-inductor SEPIC dc-dc converter for high-voltage-gain (2< G< 10) applications. It utilizes the same components as the conventional SEPIC converter with an additional diode. The voltage stress on the switch is minimal, which helps the designer to select a low-voltage and low R{mathrm {DS}-mathrm{scriptscriptstyle ON}} MOSFET, resulting in a reduction of cost, conduction, and turn ON losses of the switch. Compared to equivalent topologies with similar voltage-gain expression, the proposed topology uses lower component count to achieve the same or even higher voltage gain. This helps to design a very compact and lightweight converter with higher power density and reliability. Operating performance, steady-state analysis and mathematical derivations of the proposed dc-dc converter have been demonstrated in this paper. Moreover, extension of the circuit for higher gain (G>10) application is also introduced and discussed. Finally, the main features of the proposed converter have been verified through simulation and experimental results of a 400-W laboratory prototype. The efficiency is almost flat over a wide range of load with the highest measured efficiency of 96.2%, and the full-load efficiency is 95.2% at a voltage gain of 10.

© 2019 IEEE. This paper presents a switched-capacitor integrated (2N+1)-level (N≥2) boost inverter for single-phase photovoltaic (PV) applications. It consists of N modular switching cells, where each cell consists of two switched capacitors and three active switching elements. A boost converter at the front side of the switching cells helps to maintain the capacitor voltage balance during different operation modes. With this arrangement, the inverter is capable to generate 2N+1 output voltage levels, and able to accommodate a wide range of input voltage. Detailed analysis followed by simulation and experimental results of a 5-level inverter as an example is presented to verify the proposed concept. Further, comparison with other multilevel inverter topologies is presented to show the merit of the proposed concept.

© 2016 IEEE. Impedance-source networks are an increasingly popular solution in power converter applications, especially in single-stage buck-boost power conversion to avoid additional front-end dc-dc power converters. In the survey papers published, no analytical comparisons of different topologies have been described, which makes it difficult to choose the best option. Thus, the aim of this paper is to present a comprehensive analytical comparison of the impedance-source-based buck-boost inverters in terms of passive component count and semiconductor stress. Based on the waveform of the input current, i.e., with or without a transformer, and with or without inductor coupling, the impedance-source converters are classified. The main criterion in our comprehensive comparison is the energy stored in the passive elements, which is considered both under constant and predefined high frequency current ripple in the inductors and the voltage ripple across the capacitors. Two-level and multilevel solutions are described. The conclusions provide a 'one-stop' information source and a selection guide of impedance-source-based buck-boost inverters for different applications.

© 1982-2012 IEEE. This paper introduces a new magnetically coupled single-switch nonisolated DC-DC converter with a high-voltage gain. The topology utilizes magnetic coupling for boosting its output voltage, but unlike other converters with coupled magnetics, its voltage gain is increased by reducing its magnetic turns ratio. The name 'Trans-inverse (Tx-1)' is thus used for representing this inverse operating principle of the converter. The converter draws a continuous current from the source and is, hence, suitable for many types of renewable sources. Its leakage energy from the coupled magnetics has further been recycled and transferred to the load by an integrated regenerative snubber circuit. Its inclusion of dc-current-blocking capacitors has also helped to prevent core saturation, which, together with other performance features, has been verified experimentally.

© 1986-2012 IEEE. In this letter, a new topology called 'quasi-Y-source dc-dc converter' is presented. It inherits all the advantages of the original Y-source converter. In addition, the new topology draws a continuous current from the source, which is definitely more appropriate for most renewable sources. It also has dc-current-blocking capacitors, which will definitely help to prevent the coupled inductor core from saturation. Experimental testing has proven the validity of the proposed network and its application as a high boost dc-dc converter.

© 2015 IEEE. In this paper, a new magnetically coupled single-switch non-isolated dc-dc converter with a high voltage gain is proposed. The new topology utilizes a transformer to boost the output voltage. However, unlike other converter topologies with transformer or coupled magnetics, the voltage gain in the proposed topology is increased by reducing the turns ratio of the transformer. Hence the name Trans-inverse (Tx-1) is given to represent the inverse transformer principle of operation of the proposed converter. The new topology draws a continuous current from the source, which is required for many renewable sources. Further, the leakage energy of the transformer is recycled and transferred to the load using a passive regenerative snubber circuit. In addition, the new topology has dc-current-blocking capacitors, which avoids saturation in the transformer core. Simulation and experimental results have confirmed the validity of the proposed converter.

We present a simple and rapid prototyping technique for Field Programmable Gate Array (FPGAs)-based digital controllers for power electronics and motor drives using MATLAB's Simulink and HDL Coder design software. The MATLAB/Simulink models are optimized and converted to target independent, specific and traceable Very High Speed Integrated Circuit Hardware Description Language (VHDL) code for FPGA programming. An example implementation of the space vector pulse width modulation (SVPWM) technique is presented, illustrating the design of a generic 3-phase voltage source inverter (VSI). Simulation and co-simulation, system level design, and verification for rapid prototyping of FPGA-based digital controllers will assist power electronics engineers and researchers to develop and prototypes in a relatively short time by eliminating tedious and time-consuming manual coding. This enables increased productivity and facilitates the development of power electronic controllers with more complex control algorithms. © 2013 IEEE.

This paper presents the modulation techniques to reduce the common mode voltage (CMV) and common mode current (CMC) in 3-Φ Quasi Z-Source Inverter (q-ZSI) for AC drive systems. A modified Space Vector Pulse Width Modulation technique with reduced number of commutation per sector was used to minimize the CMV and CMC without adding extra circuitry (filters and/or leakage current isolation/bypass circuits) in a q-ZSI whilst maintaining the boost capability of q-ZSI by inserting the shoot-through vector in between the active state vector. Detailed analysis of the modified SVPWM technique to reduce the CMV and CMC of q-ZSI is presented, and performance of the proposed system has been verified using Matlab Simulink. © 2013 IEEE.

DC microgrids for power combining and distribution are of interest in many applications due to their high efficiency, relatively low cost of installation and operation, freedom from harmonic and reactive power and stability. The quasi Z-Source Inverter (q-ZSI) is a particularly promising circuit for DC Distributed Power System (DPS) because of its unique buck-boost characteristics, high power handling capability and inbuilt fault tolerance. The buck-boost capability reduces the number of power conversion stages required and provides ride-through capability during voltage sag and swells from the grid. However, the performance of q-ZSI in DC DPS under varying sources and load conditions has not previously been investigated. We present analysis and simulation of 400V DC DPS by placing q-ZSI converters in parallel under widely varying input and output conditions. An automatic master-slave control strategy was used to share the load current among parallel converters. The results verify the benefit of q-ZSI converters in DC DPS and show that DC DPS can have good transient and steady state response and is capable of maintaining stiff DC voltage at the common bus with minimal interaction. © 2013 IEEE.

This paper presents an analysis and design of a new boost type six-switch five-level Active Neutral Point Clamped (ANPC) inverter based on switched/flying capacitor technique with self-voltage balancing. Compared to major conventional 5-level inverter topologies, such as, Neutral Point Clamped (NPC), Flying Capacitor (FC), Cascaded Hbridge (CHB) and Active NPC (ANPC) topologies, the new topology reduces the dc-link voltage requirement by 50%. Whilst reducing the dc-link voltage requirement, the number and the size of the active and passive components are also reduced without compromising the reactive power capability. The analysis shows that the proposed topology is suitable for wide range of power conversion applications (for example, rolling mills, fans, pumps, marine appliances, mining, tractions, and most prominently grid-connected renewable energy systems). Experimental results from a 1.2- kVA prototype justifies the concept of the proposed inverter with a conversion efficiency of around 97.5% ± 1% for a wide load range.