Zero-voltage And Zero-current Switching Research Articles

The use of a front-end ZVZCS DC-DC converter for an IoT VFD inverter system in the paddle wheel machine drive applications

This research paper proposes the integration of power electronics and internet of things (IoT) technologies to apply in shrimp farms. By focusing on the design of a front-end converter, a three-level half-bridge (3L-HB) DC-DC converter with the zero voltage and zero current switching (ZVZCS) technique is chosen to be the front-end power converter to supply the DC bus voltage for the variable frequency drive (VFD) inverter for the paddle wheel machine in the shrimp pond. To confirm the effectiveness and possibility of the proposed concept, the circuit was theoretically designed and tested at 540 V DC of the input voltage, 700 V DC of the DC bus voltage and 3 kW of rated power. It is found that, the front-end converter can step up the DC bus to be 700 V DC which is enough for operating the VFD inverter. All switches can achieve the soft switching condition ZVZCS resulting in decreasing the switching loss and increasing the reliability of the circuit. The maximum experimental efficiency of the front-end converter is 94.9% at 75% of a full load. In addition, the introductory concept of using the IoT system also presents to improve the shrimp farming method.

태양광 발전용 단일 SiC 스위치 기반 8kW급 ZVZCS 부스트 컨버터

In this paper, tapped inductor-based high-efficiency and high-power density zero-voltage and zero-current switching(ZVZCS) boost converters are proposed for 8 kW PV applications. The proposed converter uses only one SiC switch and three SiC diodes for turn-on ZCS and turn-off ZVS operations, resulting in an efficiency of over 98.2%. This value is higher than that of the conventional converter (97.3%), which uses two switches and two diodes, considering switching and conduction losses. The proposed converters are applied to 500 and 800 V of input and output voltages for PV, respectively, and verified by simulation analysis and experimental setup with SiC high-frequency switching devices manufactured from PowerCubeSemi Co., Ltd.

A Dual-Transformer-Based Three-Level DC–DC Converter With Wide ZVZCS Switching Range

In this letter, a dual-transformer-based three-level DC-DC converter (TLDC) with wide zero-voltage and zero-current switching (ZVZCS) switching range is proposed. Compared with traditional ZVZCS TLDCs, this converter can achieve zero-voltage switching (ZVS) for the leading switches and zero-current switching (ZCS) for the lagging switches without any extra auxiliary components. By introducing an additional transformer, the energy can be transmitted during the whole switching period, and the current ripple of the output filter inductor can be reduced, resulting in a reduction in output filter inductance. Besides, the control strategy is a traditional simple phase-shift control. The circuit, operation principle and some steady-state characteristics are discussed in this letter. Finally, a 1-kW 650–800 V input and 250 V output experimental prototype is designed to demonstrate the validity and features of the proposed converter.

Coupled Inductor Based Voltage Balancing in Dual-Output CLL Resonant Converter for Bipolar DC Distribution System

Bipolar dc distribution systems face imbalances in voltages when unbalanced loads are connected at the outputs. To address imbalances in bipolar voltage levels, dedicated voltage balancers are required. However, they add extra active and/or passive components; including, magnetics, capacitors, etc. This increases the cost, reduces the conversion efficiency, and power density of dual-output converters. Therefore, to tackle the imbalances in output voltages without adding any extra active and/or passive components, this article presents coupled inductor ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CI</i> ) based voltage balancing in dual-output <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLL</i> resonant converter. The main features of the proposed method are as follows: since <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CI</i> is the result of already present resonant inductors of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLL</i> tank circuit, therefore, it does not require extra magnetic components to balance the output voltages; with no additional components, it does not increase the magnetic volume, component count, cost, and complexity of the converter; due to the direct coupling, a half of circuit inductances are integrated to achieve the respective resonant inductance of the tank circuit; and it can also avoid complex control schemes applied to voltage balancing. Besides, with the proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CI</i> , the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLL</i> converter maintains all of its good features including; zero-voltage and zero-current-switching (ZVZCS). The detailed analysis of the proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CI</i> with different load conditions is discussed. Moreover, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> or Type-12 resonant tank circuit is presented to validate ZVZCS operation in the reverse power flow condition. To verify the effectiveness of the proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CI</i> based voltage balancing, a 3.6-kW hardware prototype has been built and tested.

A phase‐shift modulated series resonant converter achieving zero‐voltage and zero‐current switching for wide output voltage range battery charging applications

In this article, a phase-shift modulated zero-voltage and zero-current switching (ZVZCS) series resonant converter (SRC) was proposed for constant current (CC) and constant voltage (CV) charging operating at the series resonant frequency. Wide output voltage range is achieved by adjusting the duty cycle of the primary inverter for CC charging and unity gain is for CV charging at full duty cycle. By tuning resonant tank parameters, discontinuous conduction mode (DCM) and boundary conduction mode (BCM) are obtained in CC charging and CV charging, respectively, which ensures zero-current switching (ZCS) of rectifier diodes and nearly ZCS of leading leg in whole charging profile. Meanwhile, a constant triangular current provided by a novel auxiliary circuit is used to implement zero-voltage switching (ZVS) for all primary MOSFETs with a reduced conduction loss. The auxiliary current is independent of duty cycle and load variation. Compared with the conventional ZVZCS phase-shift full-bridge converter with capacitive output filter, smaller conduction loss and turn-off loss can be obtained in battery charging profile. Detailed circuit operation principles and model analysis are presented. A 100 kHz/1 kW prototype is built to verify the performance.

A ZVT Auxiliary Circuit for High Step-Up Multi-Input Converters with Diode-Capacitor Multiplier

In this paper, a Zero-Voltage Transition (ZVT) non-isolated high step-up multi-input DC-DC converters is proposed which employs an auxiliary cell and diode-capacitor multiplier. The auxiliary cell has only one switch and is suitable for high step converters with diode-capacitor multiplier. In the proposed converter, all semiconductor devices operate under fully soft switching condition. The main switches turn on and turn off under Zero Voltage Switching (ZVS) condition whereas the auxiliary switch turns on under Zero Current Switching (ZCS) condition and turns off under zero Voltage and Zero Current Switching (ZVZCS) condition. Also, ZCS condition at turn-off is provided for all diodes to eliminate reverse recovery issue. The structure of the proposed converter includes two boost cells, one diode-capacitor multiplier cell, and one ZVT auxiliary circuit. Soft switching conditions for all main switches are provided by only one auxiliary circuit. The proposed converter has high step-up conversion gain without any coupled inductor. Soft switching conditions, continuous current of input sources, high efficiency, expansion capability of input sources, returning the energy of the auxiliary circuit to the diode-capacitor multiplier and low-voltage stress on switches are the main advantages of the proposed converter. The steady-state analysis of the converter and operation modes are discussed. A 160-W prototype of the proposed converter is designed and implemented. Experimental results confirm that the theoretical and the efficiency of the proposed converter reaches 96.4% at the nominal load.

High Performance Flexible Structure Three-Level DC-DC Converter: A Candidate DC Interface for Microgrids With Distributed Energy Resources

High-performance DC interfaces play a pivotal role in microgrids with distributed energy resources (DERs), which would significantly improve the utilization of DERs and the flexibility of the prosumers. For a candidate DC interface converter, how to maintain the performance over a wide operation range becomes the biggest challenge. This paper proposes a flexible structure soft-switching three-level (TL) dc-dc converter, which adds four high-speed MOSFETs and one low-speed electronic relay to achieve overall optimum performance over a wide range. Under high output or low input voltage conditions, the relay and the extra MOSFETs on the primary side are ON permanently. The proposed converter is a zero-voltage switching (ZVS) converter, which guarantees ZVS for all primary switches even under 0 load currents. Under low output or high input voltage conditions, the relay and the extra MOSFETs in the secondary side are OFF permanently. The proposed converter is a zero-voltage and zero-current switching (ZVZCS) converter, and two added MOSFETs provide ZVZCS operation not only for the main primary switches but also themselves over a wide range. Other advantages of the presented converter include reduced filter size, no primary side circulating currents, and reduced current stress of the clamping capacitor. Besides, the switching loss caused by the added power devices is low because of the full range of soft-switching operation and low on-state resistance of these devices. This paper discusses the circuit configuration, operation principle, soft switching characteristics, technical comparison, and experimental results from a 1-kW prototype prove the rightness of the presented converter.

Optimized Design of 1 MHz Intermediate Bus Converter Using GaN HEMT for Aerospace Applications

This paper presents the possibility of using Gallium Nitride (GaN) high-electron-mobility transistors (HEMTs) instead of the conventional silicon metal oxide semiconductor field effect transistor (MOSFET) to implement a high-frequency intermediate bus converter (IBC) as part of a typical distributed power architecture used in a space power application. The results show that processing the power at greater frequencies is possible with a reduction in mass and without impacting the system efficiency. The proposed solution was experimentally validated by the implementation of a 1 MHz zero-voltage and zero-current switching (ZVZCS) current-fed half-bridge converter with synchronous rectification compared with the same converter using silicon as the standard technology on power switches and working at 100 kHz. In conclusion, the replacement of silicon (Si) transistors by GaN HEMTs is feasible, and GaN HEMTs are promising next-generation devices in the power electronics field and can coexist with silicon semiconductors, mainly in some radiation-intensive environments, such as power space converters. The best physical properties of GaN HEMTs, such as inherent radiation hardness, low on resistance and parasitic capacitances, allow them to switch at higher frequencies with high efficiency achieving higher power density. We present an optimized design procedure to guaranty the zero-voltage switching condition that enables the power density to be increased without a penalization of the efficiency.

Analysis and Design of ZVZCS Full-Bridge Converter With Reduced Components for Input-Series-Output-Parallel Application

Different from the conventional performance improvement of a single phase-shift full-bridge (PSFB) converter by adding auxiliary components, this article utilizes the intrinsic advantage of multimodule in the input-series-output-parallel (ISOP) application to achieve zero-voltage and zero-current switching (ZVZCS) operation of switches and reduce the duty-cycle loss and conduction loss in two PSFB converters through their interaction. The interaction is established by sharing the secondary rectifier diodes, and hence the number of components used in the proposed converter is reduced compared with the ISOP PSFB converter. Moreover, the voltage stress of the shared diodes is reduced. As a consequence, lower cost is achieved along with the improved performance. In this article, operational principle and relevant analysis of the proposed ZVZCS PSFB converter with reduced components are presented in detail to obtain a comprehensive understanding. Besides, its small-signal model is gained and a closed-loop control scheme is accordingly designed to improve the dynamic performance. Finally, the favorable advantages of the proposed converter are experimentally verified in a prototype circuit with 400 V input and 120 V/500 W output.

ZVZCS Full-Bridge Three-Level DC/DC Converter With Reduced Device Count

This letter proposes a new zero-voltage and zero-current switching (ZVZCS) full-bridge (FB) three-level dc/dc converter (TLDC) with the reduced device count. The merits of the proposed converter with the corresponding modulation strategy are concluded as follows. In comparison with the zero-voltage-switching FB TLDC: 1) only one blocking capacitor is added to realize the ZVZCS strategy, 2) the primary circulating current and duty cycle loss can be effectively reduced. Also, the wide input voltage range can be satisfied because of having two working patterns. More significantly, the proposed converter with the corresponding modulation strategy can reduce the device count by removing the primary blocking diodes in comparison with other ZVZCS FB TLDCs, which would reduce the conduction losses of primary power devices and thus increase the converter's efficiency. Finally, experimental results are presented to verify the proposed converter with the corresponding modulation strategy.

Large Power Hybrid Soft Switching Mode PWM Full Bridge DC–DC Converter With Minimized Turn-on and Turn-off Switching Loss

A novel PWM full bridge (FB) dc–dc converter for large power industrial applications is proposed in this paper. The soft switching mode of the primary switches can be varied under different input and output conditions to achieve optimum system efficiency. In the zero-voltage and zero-current switching (ZVZCS) mode, the turn- on and turn- off switching loss can be optimized because the soft switching conditions of the turn- on and turn- off instants are well decoupled. In the zero-voltage switching (ZVS) mode, the turn- off switching loss can also be optimized because there is no requirement for light load operation in this mode. Four mosfet s with ultra-low on-state resistance are used, thus, the added conduction loss is small. The auxiliary mosfet s with high switching frequency are turned on with zero-current and off with zero-voltage, hence, the added switching loss can also be neglected. Furthermore, some drawbacks of the conventional ZVS and ZVZCS converters, e.g., narrow ZVS load range, high primary circulating current, incomplete reset of the primary current, and unreasonable VA rating of the added components, have been well solved. The operation principles and soft switching characteristics are discussed. Experimental results from an 18-kW prototype are provided to verify the proposed converter.

Large-Power ZVZCS Full-Bridge Three-Level DC–DC Converter With Wide Operation Range and Its Application in Sapphire Crystal Furnace Power Supply

A novel zero-voltage and zero-current switching (ZVZCS) full-bridge (FB) three-level (TL) dc-dc converter is proposed, which can satisfy most requirements of wide operation range high-input dc-dc industrial applications. OFF-voltage on the primary switches can be maintained to V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in</sub> /2 by the input capacitors, and no extra primary clamping device is needed. The primary switches can obtain zero-voltage switching (ZVS) or zero-current switching (ZCS) easily. Furthermore, the operation mode can be altered under different output and input conditions, which ensures high efficiency over a wide operation range. The extra MOSFETs have low ON-state resistance and cause less switching loss; thus, the power loss caused by these MOSFETs can be omitted. Furthermore, these components are not inserted into the circuit loop of the input capacitors and primary switches, which may reduce the voltage spike on the primary switches at turn-off instants. The VA rating of the primary switches and input capacitors is identical to that of conventional FB TL dc-dc converters, and the utilization of the dc-link voltage is close to 100%. To evaluate the proposed converter, an industrial application example and some experimental results are also provided.

Wide Load Range ZVZCS Three-Level DC–DC Converter With Compact Structure

To fit the requirements of high input dc–dc power conversion, a novel zero-voltage and zero-current switching (ZVZCS) three-level dc–dc converter is proposed. Some advantages of the proposed converter are concluded as follows. The off voltages on the primary switches are clamped around V in/2 by the input capacitors and the blocking capacitor. A total of two mosfet s with low VA rating are added to provide ZVZCS for the main switches in a wide load range. The switching loss of the main switches can be optimized because the soft-switching conditions of the turn- on and turn- off instants are well decoupled. The primary components can achieve reduced current stress and even current distribution because the primary current is zero during the free-wheeling stages. As the current of the auxiliary mosfet s is zero during most operation stages, the added conduction loss can be neglected. Furthermore, the added switching loss can also be neglected because these mosfet s can achieve zero-voltage turn- off and zero-current turn- on . The circuit, operation principles, and some technical analyses are discussed in this letter, and experimental results are also provided to evaluate the proposed converter.

A Hybrid Resonant ZCS PWM Converter for Renewable Energy Sources Connecting to MVDC Collection System

To relieve the tail current effect of insulated-gate bipolar transistors which are preferred in high-power applications, an approach of zero-current-switching (ZCS) for main switches is presented in this paper. Different from the large turn-off current of the main switches of the conventional zero-voltage and zero-current-switching (ZVZCS) full-bridge (FB) dc-dc converter, small turn-off current of auxiliary circuit is introduced to achieve ZCS for main switches, where the auxiliary circuit also delivers a small portion power and can realize ZVZCS. Hence, high efficiency can be achieved with the switching loss lowered remarkably. Furthermore, a hybrid resonant FB dc-dc converter is proposed, the operation principle and parameters design rules of which are analyzed in detail. A 200 V-2 kV/3 kW experimental platform has been built to verify the feasibility and performance of the proposed ZCS approach, as well as the proposed converter.

Design of 10kW three-phase EV charger with wide output voltage range based on voltage-fed isolated PFC converter

ABSTRACTThis article presents a design of the three-phase Electric vehicle (EV) charger with a wide-output voltage range. The proposed charger is based on a voltage-fed/isolated power factor correction (PFC) converter followed by a non-isolated DC/DC converter. The three-phase PFC converter come from asymmetrical dual active bridge (ADAB) converter having zero-voltage- and zero-current-switching (ZV-ZCS) operation in the primary side so that a low-cost device such as Insulated gate bipolar junction transistor (IGBT) is available despite of a high switching frequency. Also, since the PFC converter adopts the harmonic modulation technique that can be implemented in a simple equation, all the controls for the three-phase PFC converter and the non-isolated DC/DC converter can be implemented with a simple digital controller by excluding fast current loops for input current harmonic regulation. The feasibility of the proposed charger has been verified with a 10kW prototype.

Analysis of Strategy for Achieving Zero-Current Switching in Full-Bridge Converters

Conventional zero-voltage and zero-current-switching (ZVZCS) full-bridge converters are widely used because they can realize zero-voltage switching (ZVS) for the leading leg and zero-current switching (ZCS) for the lagging leg. However, the large turn-off loss of the leading leg is still unacceptable in high-voltage high-power applications where insulated-gate bipolar transistors (IGBTs) with current tailing are employed. Hence, it is preferable to achieve ZCS for all IGBTs of full-bridge converters. This paper analyzes the ZCS conditions for pulsewidth modulated (PWM) full-bridge converters and proposes a general strategy for achieving ZCS for main switches, including the control strategy and design method of the topology. Based on this theory, a novel ZCS PWM full-bridge converter with simple auxiliary circuit is derived and tested. It can achieve ZCS not only for the main switches of full-bridge converter, but for the auxiliary switch as well, and obtain high efficiency. The operation principle of the proposed ZCS PWM full-bridge converter and the design procedure are presented. The experimental results of a 600 V/2.5 kW prototype are also included to verify the theoretical analysis.

A Resonant ZVZCS DC–DC Converter With Two Uneven Transformers for an MVDC Collection System of Offshore Wind Farms

A resonant zero-voltage and zero-current-switching (ZVZCS) dc–dc converter is proposed in this paper for a medium-voltage dc collection system of offshore wind farms. The resonant converter is composed of two full-bridge cells sharing a bridge leg, two transformers with uneven power ratings and different functions, whose secondary windings are connected in series and a voltage-doubler rectifier. The converter operates in discontinuous current mode and can achieve zero-current switching for four main power switches and rectifier diodes over the whole load range. The two auxiliary switches with small forward current can be turned on with ZVZCS, and turned off with zero-voltage switching. Hence, the switching loss can be reduced and efficiency is improved. The operation principle of the converter is analyzed and design rules of main parameters are presented. The influences of the turn ratios of auxiliary transformer and resonant capacitance on the peak and switching-off currents are discussed in detail. Furthermore, a model is built in PLECS and simulation results are given. A 150–1500 V/2 kW prototype is established and tested to verify the operation principle and design rules.

Full soft‐switching high step‐up DC–DC converter based on active resonant cell

In this paper, a new full soft switching high step-up DC–DC boost converter is proposed. To achieve high voltage gain, a N-level voltage multiplier cell (VMC), and to achieve soft switching, a simple auxiliary resonant cell is implemented on a conventional pulse width modulation boost converter. All semiconductor devices are switched under soft switching conditions, which decrease the switching losses significantly. These soft switching conditions consist of zero voltage and zero current switching (ZVZCS) condition for both main and auxiliary switches, ZVZCS for auxiliary cell diode and zero current switching for all output VMC diodes. To control the output voltage in this converter, two degrees of freedom, consisting of the main switch duty cycle and output VMC level (N), are available. These degrees of freedom lead the converter to operate in a wide output voltage range and have maximum power point tracking implementation or output voltage regulation capabilities. In this paper, operational modes analysis, design procedure, application discussion, soft switching and power efficiency evaluations and simulation results are presented. Finally, experimental results with input voltage of 32 V, output power of 80 W and switching frequency of 20 kHz are given to prove the accuracy of theoretical analysis.

Analysis, Design, and Implementation of an APWM ZVZCS Full-Bridge DC–DC Converter for Battery Charging in Electric Vehicles

An efficient power converter system plays a significant role in the design of battery charging systems for electric vehicles (EVs). In this paper, a new zero-voltage and zero-current switching (ZVZCS) full-bridge dc–dc converter is proposed to reduce the power conversion losses. The proposed converter incorporates a new asymmetrical pulse width modulation (APWM) gating technique for the dc–dc conversion stage in the battery charging system. The proposed dc–dc converter topology achieves zero-voltage switching (ZVS) for all the active switches and near zero-current switching (ZCS) for low-side active switches throughout the charging range of the battery. The proposed APWM technique can reduce the switching and conduction losses compared to the conventional phase-shift modulation (PSM) gating technique. The auxiliary inductance required to ensure ZVS with APWM can also be reduced compared to PSM. Analysis, design, and implementation of the proposed APWM ZVZCS full-bridge dc-dc converter are discussed in this paper. A 100-kHz 1.2-kW laboratory prototype is developed and the experimental results are presented. The results validate the analysis and performance of the proposed converter.

Interleaved full ZVZCS DC–DC boost converter: analysis, design, reliability evaluations and experimental results

In this study, a new interleaved full soft switching DC-DC boost converter with a high power reliability is proposed. To achieve soft switching, a simple auxiliary circuit consisting of one switch, one diode, one inductor and two capacitors is employed in each single-phase DC-DC boost converter connected in parallel. All switches and diodes, including main and auxiliary ones, operate under soft switching conditions. These soft switching conditions consist of zero voltage and zero current switching (ZVZCS) for all switches and diodes at switching transitions except the output diodes, which turn off only with zero current switching. The soft switching technique used in this study decreases power losses which leads the converter to have higher efficiency and reliability. Also, the auxiliary circuit is located out of the main power path preventing high voltage and current stresses on the switches. In this study, operational modes analysis, design procedure, power reliability evaluations and laboratory prototype results with switching frequency of 20 kHz, input voltage of 48 V and output power of 40 W are presented.