Conventional Converter Research Articles

Design and analysis of isolated high step-up Y-source DC/DC resonant converter for photovoltaic applications

ABSTRACT This paper presents the design and analysis of an isolated high step-up Y-source DC/DC converter for photovoltaic systems. At high switching frequencies, the conventional impedance source converter (ISC) experiences higher switching losses. To mitigate this, a high gain soft-switched frequency-modulated Y-source DC/DC converter is proposed. Here, soft switching is implemented on the Y-source impedance converter by creating quasi-resonance during a shoot-through instant. Thus, quasi-resonance occurs by an LC resonant tank, and it is formed using a resonant capacitor and leakage inductance of a transformer. It ensures that all the active switches are turned off with zero current switching (ZCS) and the voltage stress on each switch is much lower than the output voltage with lower turn-off voltage spikes. Thus, it eliminates the need for a snubber circuit. The output voltage is regulated by frequency modulation with the ON period of all four active switches kept constant. The converter can also deliver a continuous input current (CIC) and high voltage gain with a small shoot-through duty ratio . The galvanic isolation of the converter helps to eliminate the leakage current issues and safety hazards faced by the non-isolated counterparts. The proposed topology has all the inherent characteristics of a typical impedance source DC/DC converter with higher conversion efficiency over a wide range of output loads. The proposed converter achieves 96.46% of full load efficiency. Finally, a 200W prototype is built and tested in the laboratory to verify the converter design and performance.

Dual Output and Dual-Frequency Resonant Inverter-based Induction Heating Using ADC Control

A dual output dual-frequency (DODF) resonant converter-based AC-AC induction heating (IH) by using asymmetrical duty cycle (ADC) control is presented in this paper. The proposed scheme gives two outputs with independent power control, which improves input power factor and achieves zero voltage switching (ZVS) with a wide range of operations. It includes two pairs of two half-bridge series resonant converters, each pair having one common capacitor along with various resonant frequencies. These converters are modulated with the ADC control scheme to obtain smooth operation. The proposed topology doesn’t use the DC stage; it is directly connected to the power supply to produce high-frequency AC output. With the use of direct connection, the converter components are reduced when compared to conventional converters. There will be a reduction in voltage drop, power losses, cost of the converter and which will result in improved efficiency. Simulation results are obtained from PSIM 11.1.7 software. This scheme controls two different loads with an efficiency of 98.25%.

An Isolated Three-Port Power Converter with 2C3L and 2C2L Resonant Circuits

This study proposed an isolated three-port bidirectional resonant converter that combines 2C3L and 2C2L resonant circuits for application in power dispatching. The proposed converter improves the bidirectional power dispatch capabilities of conventional three-port converters and utilizes different resonant converters to complete the energy charge–discharge through ports of different voltage levels. By modulating the frequency alone, bidirectional power regulation and electrical isolation were achieved among the three ports with different voltage levels. The converter involves the use of resonance techniques to enable the power switch to perform soft switching during bidirectional power transmissions, reducing switching loss and electromagnetic interference. The system control of the circuit was a Texas Instruments TMS320F28335 microcontroller. By simulating a DC grid port with a fixed voltage of 400 V, a vehicle battery port with a variable voltage of 280–403 V, and a battery charging port with a variable voltage of 180–213 V, an experimental platform with a rated output of 3 kW was built to determine the accuracy of the proposed theoretical analysis and design method.

A 24 V to 1 V integrated dual-charging path dual-inductor hybrid converter for improved step-up load transient response

This paper proposes a dual-charging-path dual-inductor hybrid converter that can charge two inductors simultaneously to improve the step-up load transient response. The proposed scheme only introduces one additional switch and capacitor to form a dual charging path during step-up load transient response. All power switches are integrated using 5 V transistors with 0.25 μm HV BCD process. Using type-3 PWM control combined with a fast load transient detector, simulation results show that the proposed circuit achieves 55.4% voltage drop and 23.6% recovery time reduction compared to the conventional DIH converter for load transient step from 20 mA to 4 A.

A High Efficiency Modified Forward Converter for Solar Photovoltaic Applications

In this paper, a modification of a conventional forward converter and a new mixed-stranded transformer winding technique are proposed for the development of a simple and high efficiency isolated dc-dc boost converter for solar photovoltaic applications. The conventional single switch forward converter topology is modified for simplification and elimination of losses due to the output filter components. A new mixed-stranded transformer winding technique is proposed to minimize the leakage inductance between the primary and tertiary windings for reducing losses. A pulse frequency modulation technique (PFM) is employed for reducing switching losses at low power operation. An experimental prototype of 300 W with a voltage step-up ratio of 1:12 has been built to obtain dc output voltage between 360-480 V for the dc input voltage of 30-40 V. Through the experimental results, it is shown that the converter can boost the input voltage according to the step-up ratio and exhibits a remarkably high dc-dc power conversion efficiency with a flat response curve. The average efficiency of around 95.5 % and peak efficiency of 97.6% are obtained.

Design and Modeling of Modified Interleaved Phase-Shifted Semi-Bridgeless Boost Converter for EV Battery Charging Applications

Electric vehicles (EVs) are set to become one of the domestic transportation systems that are highly preferred over conventional vehicles. Due to the huge demand for and cost of fuel, many people are switching over to EVs. Companies such as Tesla, BMW, Audi, and Mercedes have started marketing EVs. These EVs need charging stations to charge the batteries. The challenges for EV batteries require the implementation of features such as fast charging, long-run utilization, reduced heat emission, a light weight, and a small size. However, fast charging using conventional converters generates an imbalance in current injection due to the passive component selection. In this study, a converter is proposed that uses an interleaved network that provides a balanced current injection; i.e., an improved interleaved phase-shifted semi-bridgeless boost converter (IIPSSBBC) is designed for EV battery charging applications. The suggested approach is mathematically designed using MATLAB/Simulink (2021) software. The result shows that the battery charging current achieves about 16.5 A, which is relatively more than conventional systems. Moreover, the charging time of the proposed converter is about 6 hrs for a 50 Ah battery with a discharge load capacity of 5000 W, which is relatively less than the conventional method. In a nutshell, compared with conventional converters, the IIPSSBBC performs better, and, notably, the charging speed and current injection are increased by two times the amount. Further, a prototype hardware model is developed to assess the performance of the proposed converter.

A Novel Bidirectional Wider Range of Boost-Buck Three-Level LCC Resonant Converter as an Energy Link

In order to maintain different voltage levels between the front and rear dc terminal bus derived from new energy industry, a novel bidirectional wider range of boost-buck three-level LCC resonant converter as an energy link is proposed by combining the LCC resonant tank module with a particular three-level coupling cascaded neutral point clamping active bridges, which is composed of two three-level neutral point clamping bridge arms. Furthermore, the converter can, respectively, establish forward LCC and backward SRC working modes to maintain unified wider bidirectional voltage gain range between the input and output by asymmetric structure of LCC resonant tank module that boost-voltage is enabled by equivalent principle of conventional LCC resonant converter and buck-voltage is enabled by equivalent principle of conventional series resonant converter, while, a unified bidirectional boost-buck voltage gain matching control strategy is designed with an optimization about parameters of LCC resonant tank module under realizing of zero voltage switching-on and reducing of reactive power losses. Finally, according to the simulation platform and experimental prototype, it can be shown that the practical voltage gain is closed to the theoretical designed gain and converter has good dynamic performances after realizing of soft-switching in each mode.

Two-Switch Forward Converter With an Integrated Buck Converter for High Bus Voltage in Satellites

As satellite missions become increasingly diverse, the power capacity of satellites continues to increase. Accordingly, the weight and loss of the electrical power system of the satellite must be reduced. Thus, a high bus voltage is required for the electrical power system of the satellite. However, most high-power dc/dc converter topologies, such as half-bridge and full-bridge dc/dc converters have leg-structures, which violate the heritage design characteristics of the dc/dc converters for satellites. To solve these problems, a two-switch forward converter with an integrated buck converter is proposed in this article. By integrating the buck converter into the two-switch forward converter, one switch and one diode are eliminated in the proposed converter, and consequently, its cost, weight, and volume can be greatly reduced. Moreover, the zero-voltage switching of the low-side switch can be achieved. Therefore, the proposed converter achieves a high efficiency under the entire load condition compared with conventional converters. The effectiveness and feasibility of the proposed converter were verified with a prototype of 300–330 V input and 600 W (150 V/100 V) output.

An Efficient Soft-Switching Buck Converter With Parasitic Resonance Suppression in Auxiliary Circuit

In this article, a new efficient soft-switching synchronous rectification (SR) buck converter is proposed, which is without voltage stress increment for all switches and diodes. By introducing an auxiliary circuit to the SR buck converter,the soft-switching condition is achieved within the wide range of load power for the power semiconductor devices. The auxiliary network, which consists of capacitor, inductor, switch, and three diodes, provides a zero-voltage condition for main switch and SR switch at both the turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and the turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> instant. Besides, the auxiliary inductor creates a zero-current turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and a zero-voltage turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> condition for the auxiliary switch. Considering the resonance between the parasitic capacitors of the semiconductor components and the auxiliary inductor, two diodes are designed to avoid the additional voltage stress on power devices. The operating principle of this proposed converter is analyzed. A 600 W prototype is implemented to test the soft-switching operation. The advantage of the proposed converter is demonstrated by the efficiency curve over a wide range of load power against the conventional SR buck converter .

A Split-Inductor Flying Capacitor Converter for Medium-Voltage Application

This article presents a split-inductor flying capacitor (SIFC) converter for medium-voltage applications to improve reliability and eliminate the shoot-through issue. Reliability and lower total harmonic distortion (THD), mainly caused by the pulsewidth modulation (PWM) dead time, are the vital aspects while designing higher power density converters. The dead time in the PWM can be reduced/removed in the proposed converter. This will increase the voltage/current gain and enhance the quality of the voltage/current waveforms even at lower modulation index and light loads than the traditional flying capacitor (FC) and neutral point clamped (NPC) converters. Furthermore, an improved phase-shifted PWM (IPS-PWM) is used to maintain the flying capacitor’s nominal reference voltage. A comparison is made between SIFC and five different existing multilevel topologies. The proposed converter has higher voltage/current gain, lower THD over conventional FC and NPC converters, and higher efficiency than the other three topologies. Finally, the SIFC converter’s robustness with IPS-PWM is validated using experimental results in different operating conditions such as sudden load changes, modulation index, output frequency, and power factor (unity, lagging, and leading).

Novel Controllable-Line-Commutated Converter for Eliminating Commutation Failures of LCC-HVDC System

To entirely eliminate commutation failure (CF) in conventional line-commutated converter based high-voltage direct current (LCC-HVDC) transmission system, a novel controllable line-commutated converter (CLCC) based on the combination of partially and fully controllable semiconductor devices is presented in this paper. The operating principle of CLCC and its control strategy are proposed. In addition, the voltage and current stress are analyzed. To verify correction and application of presented CLCC solution to the project, a CLCC-HVDC system model, adopting LCC at the rectifier side and CLCC at the inverter side, is developed in PSCAD/EMTDC software. Based on the model, the transient responses of the CLCC-HVDC system under various AC faults are simulated and compared with the pure LCC-HVDC. Simulation results show that the presented CLCC topology and its control strategy can not only eliminate CFs in various types of AC faults, but also improve the transient performance of the system after faults, while inheriting the attributes of traditional LCC such as large capacity, low cost and almost the same system control strategy. This is quite positive and meaningful for application of the CLCC-HVDC to multi-DC infeed system particularly.

A Dual-Transformer-Based Hybrid Dual Active Bridge Converter for Plug-in Electric Vehicle Charging to Cope With Wide Load Voltages

A dual-transformer-based hybrid dual active bridge (DAB) converter for plug-in electric vehicle charging to cope with wide load voltages is introduced in this article. The control degrees of freedom are extended by splitting the leg and transformer of the conventional DAB converter (CDABC) in two parts. Based on the numerical analysis, the full-domain four-variable closed-form optimal trajectories targeting at the minimum root mean square value of the leakage inductor current is attainted, and the unified-segmental control strategy is proposed to handle the working modes shifting without the current inrush. As a result, the conduction losses and switching losses can be significantly reduced in boost mode compared to CDABC. The discussed converter and control strategy are verified by a 1.0-kW prototype.

Comprehensive Analysis and Experiments of RB-IGCT, IGCT With Fast Recovery Diode and Standard Recovery Diode in Hybrid Line-Commutated Converter for Commutation Failure Mitigation

Commutation failure is one of the most important factors threatening the safety of multi-infeed high voltage direct current systems. To mitigate commutation failure, we have proposed a novel hybrid line-commutated converter by adding fully controlled devices to the conventional line-commutated converter. It aims to achieve auxiliary commutation and forced commutation with the help of fully controlled devices. Based on the novel hybrid line-commutated converter topology, the study investigates how to select suitable fully controlled devices and how to design the appropriate parameters of the devices. First, this article studied the general characteristics of reverse-blocking devices, including reverse-blocking integrated gate-commutated thyristor (RB-IGCT) and asymmetrical IGCT with diode (including fast recovery diode and standard recovery diode). Then, the novel commutation principle is carefully proposed and analyzed. The comprehensive simulation results and comparison study of the novel commutation principle are conducted. Then, according to the proposed commutation principle, the voltage and current working stress of devices are illustrated. According to these, vital features of devices, including recovery speed, <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -state voltage, current conduction ability, surge current, maximum turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> current, robustness, and volume of devices, are carefully analyzed and compared. Related experiments are conducted to present the vital characteristics of devices in the equivalent operating conditions in converters. Finally, the advantages and disadvantages of RB-IGCT and IGCT with fast recovery diode and standard recovery diode are comprehensively presented, which offers valuable reference considered in engineering applications.

Half-Bridge LLC Series-Resonant Converter With Hybrid Rectifier for LED Signage Backlighting Systems

Large-area LED signage backlighting systems require power supplies to provide constant voltage to multiple LED modules connected in parallel, each with a built-in LED current regulator to maintain a constant output brightness. LED signage backlighting systems can be divided into 12 V and 24 V, which require different power supply specifications. The development of a universal 2-in-1 LED driver will reduce the number of power supply models and avoid incorrect wiring in the field. A new topology of half-bridge LLC series-resonant converter with hybrid rectifier is proposed in this brief, which automatically switches between full-bridge rectifier and half-wave rectifier by LED current detection. The hybrid rectifier switching mode enables an optimized design with two times the output voltage range, thus reducing the switching frequency range and the circulating current of the LLC series-resonant converter. The performance of the 60 W half-bridge LLC series-resonant converter with hybrid rectifier and the conventional half-bridge LLC series-resonant converter is experimentally compared. The results prove that there is a significant improvement in efficiency based on the 24 V output condition.

A new Inductorless single capacitor step down DC-to-DC converter design

Conventional switched capacitor filter circuits require a number of capacitors for their implementation with attendant complexity, efficiency and power density costs. In this work, a simple hysteresis-controlled switched capacitor circuit requiring a single capacitor for its implementation was proposed, modeled, simulated with MULTISIM® software and also prototyped. Dependent variations in switching frequency and power density reveal that the converter has a relatively constant output ripple voltage and its efficiency figure approaches that of a conventional linear step-down converter over the same output power range.With a single capacitor and switch requirements, the circuit has a reduced complexity compared to other switched-capacitor converters.

AN ENHANCED POWER DC-AC BUCK CONVERTER

ABSTRACT: This paper presents an enhanced power DC-AC buck converter.The main aim of this research paper is to ensure that the conventional H-bridge DC-AC buck converter is operated practically without delay time between the complementary power switches on the same leg.The enhanced version is realized by serially connecting sized inductor-capacitor-diode topology between the drains and the sources of the high sides of the H-bridge converters. The significant improvement in this kind of converter is that it offers short-circuit immune systems that are not obtainable in the traditional buck DC-AC converter and it triggers the complementary power switches without delay time. The power circuit is obtained by an amalgamation of two Y-closed-up topologies to form an H-bridge converter. The proposed system has a power rating of 3.25 kW, THD of 0.2717%, and pure sine waveforms of output voltage and currentof 311.00V and 10.63A under resistive loads. Under RL loads, it offers 3.25 kW, THD of 0.2807%, and pure sine waveforms of output voltage and current of 297.5V and 10.925A Keywords: DC-AC Converter, traditional, Buck, Enhanced, Power

Parameter extraction and selection for a scalable N-type SiC MOSFETs model and characteristic verification along with conventional dc-dc buck converter integration.

Most silicon carbide (SiC) MOSFET models are application-specific. These are already defined by the manufacturers and their parameters are mostly partially accessible due to restrictions. The desired characteristic of any SiC model becomes highly important if an individual wants to visualize the impact of changing intrinsic parameters as well. Also, it requires a model prior knowledge to vary these parameters accordingly. This paper proposes the parameter extraction and its selection for Silicon Carbide (SiC) power N-MOSFET model in a unique way. The extracted parameters are verified through practical implementation with a small-scale high power DC-DC 5 to 2.5 output voltage buck converter using both hardware and software emphasis. The parameters extracted using the proposed method are also tested to verify the static and dynamic characteristics of SiC MOSFET. These parameters include intrinsic, junction and overlapping capacitance. The parameters thus extracted for the SiC MOSFET are analyzed by device performance. This includes input, output transfer characteristics and transient delays under different temperature conditions and loading capabilities. The simulation and experimental results show that the parameters are highly accurate. With its development, researchers will be able to simulate and test any change in intrinsic parameters along with circuit emphasis.

Design and Analysis of Quasi-Y Source High Gain DC/DC Resonant Converter for Renewable Energy Applications

This paper proposes a magnetically coupled partial resonant isolated quasi-Y source DC/DC converter. Here, to achieve soft switching, there is no additional auxiliary circuits or magnetic components are used. By making use of transformer’s parasitic elements like winding capacitance (Cp) and leakage inductance (Lk1), zero current switching (ZCS) is obtained at the turn-off instant of all MOSFETs. Hence, the converter can operate at a higher frequency, so that compact size and good efficiency are feasible. This converter inherits all the conventional impedance source converter features, and a higher gain is obtained by using three winding coupled inductor and isolation transformer with small shoot-through duty (dST). Hence, the continuous input current (CIC) and galvanic isolation feature of this converter is most suitable for renewable energy applications. Also, the output voltage is regulated by changing the switching frequency. Finally, a 300 W prototype is designed and tested in the laboratory. The simulation, experimental results with mathematical and design analysis are provided.

A Common Capacitor Hybrid Buck-Boost Converter

DC-DC converters are electronic circuit elements that are frequently used to change the direct current (DC) level. This paper presents a hybrid buck-boost converter - with constant modulation index - that can change a DC voltage at two directions compared to the conventional buck-boost DC-DC converters. First, the circuit structure and operation are given. Then, the performance of the proposed converter is tested on resistive and inductive loads, and compared with that of conventional buck-boost converters. The obtained results demonstrate the effectiveness of the proposed converter. They unveil that the proposed converter - compared to the conventional buck-boost converters – produces a higher and flexible rate of conversion without changing the operating ratio of the switches. Moreover, the proposed converter is able to change the voltage on double way on load for a constant operating ratio, while the traditional converters provide a one-way conversion.

Three-Port Forward Converters With Compact Structure and Extended Duty Cycle Range

A series of three-port forward converters with a compact structure and extended duty cycle range is presented for the standalone renewable energy system. Bidirectional power-flow port embedding and switch device sharing can be used to derive these converters from conventional two-switches forward converters. In comparison to the conventional two-switch forward converter, only one switch and one diode are added to build an energy storage port with bidirectional power flow characteristics, which has the benefits of compact structure and low cost. Meanwhile, the embedding of the energy storage port provides an additional demagnetization loop for the magnetic inductor, which extends the duty cycle range of the forward converter so that the proposed converter no longer requires a duty cycle of less than 0.5 as in the case of conventional forward converters. The proposed converters also offer the advantages of fewer components, easy control, and independent control of power flow between multiple ports when compared to similar solutions. Finally, an experimental setup with a photovoltaic battery as an application is developed, and the experimental results verify the effectiveness and flexibility of the proposed topology and control method.