Current Stress Of Switches Research Articles

A novel bidirectional DC–DC converter with high voltage conversion ratio and capability of cancelling input current ripple

AbstractThis paper proposes a novel bidirectional DC–DC converter with high voltage conversion ratio and capability of cancelling input current ripple. The proposed converter uses two coupled inductors and switched‐capacitor circuit to increase the voltage conversion ratio. The input current ripple at low voltage side can be eliminated for a pre‐selected duty cycle by adjusting special values of magnetizing inductances of coupled inductors. The input current is divided into two paths of the primary winding of coupled inductors that causes the decrease in the current stresses of switches. The proposed converter has five switches that consist the internal diodes of switches to bring about bidirectional power flow and have boost and buck operations. Here, the proposed topology is analysed in all operating modes and the current and voltage stresses of switches, input current ripple cancelling condition and voltage conversion ratio are calculated. Finally, the accuracy performance of the proposed converter is reconfirmed through EMTDC/PSCAD simulation and experimental results for boost operations.

Analysis and validations of operation behaviors for dual active bridge‐based unified power quality conditioner under different working conditions

AbstractIn this paper, a dual active bridge‐based unified power quality conditioner (DAB‐UPQC) is constructed to solve the bulky issue caused by a line‐frequency transformer (LFT) in conventional UPQC. Since there is no LFT, the constructed DAB‐UPQC is easier to realize modular manufacturing, which further increases the flexibility of system. After adding DAB, the UPQC will present two obvious changes as follows: (a) Almost all of the grid input current flows through the series converter, resulting in an increase in the current stress of switches in the series converter. (b) The dc link is allowed to contain both low‐ and high‐voltage amplitudes due to the voltage ratio of high‐frequency transformer in DAB. Considering these two changes, the operation behaviors of DAB‐UPQC are analyzed in detail, which has the valuable significance for designs of DAB, series and parallel converters. Additionally, the characteristics and implementation conditions of soft‐switching for DAB with single‐phase‐shift (SPS) modulation are analyzed and discussed, and the battery bank is integrated on the low‐voltage side of dc link to provide continuous power to the load in the event of the grid outage or failure. Finally, the operation performances of DAB‐UPQC under the conditions of grid voltage sag/swell, nonlinear load, and grid outage are verified by using a hardware‐in‐the‐loop (HIL) experimental platform.

A Coupled-Inductor Interleaved LLC Resonant Converter for Wide Operation Range

In this paper, a coupled-inductor interleaved LLC resonant converter (CI-ILLC) was proposed, which can achieve extensive operation range applications by multiplexing inductors and switches. In this proposed CI-ILLC, the coupled-inductor not only serves as a filter inductor but also plays the role of transformer to improve the power density. By changing the modulation methods, the proposed converter can work at three modes for a wide operation range, namely high gain (HG) mode, medium gain (MG) mode, and low gain (LG) mode. Moreover, the interleaved structure greatly reduces the current ripple and current stress of switches. Besides, in HG and MG modes, all switches can realize zero-voltage switching, with high energy transmission efficiency. Finally, the simulation and experiment results of the prototype with 120–200 V input and 50–200 V output are presented to verify the viability of the proposed converter.

A New Transformer-Less Structure for a Boost DC-DC Converter with Suitable Voltage Stress

In this paper, a new structure is proposed for a boost dc–dc converter based on the voltage-lift (VL) technique. The main advantages of the proposed converter are its lack of transformer, simple structure, free and low input current ripple, high voltage gain capability by using an input source, suitable voltage stress on semiconductors and lower output capacitance. Herein, the analysis of the proposed converter operating and its elements voltage and current relations in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) are presented, and the voltage gain of each operating mode is individually calculated. Additionally, the critical inductance, current stress of switches, calculation of passive components’ values and efficiency are analyzed. In addition, the proposed converter is compared with other studied boost converters in terms of ideal voltage gain in the CCM and the number of active and passive components, maximum voltage stress on semiconductors, and situation of input current ripples. The correctness of the theoretical concepts is examined from the experimental results using the laboratory prototype.

Staggered parallel asymmetric boost converter based on coupled inductor

Aiming at the problems of insufficient voltage gain, excessive voltage stress and current stress of switches in DC boost converters, an interleaved parallel asymmetric boost converter is proposed. The circuit adopts interleaved parallel boost converters, coupled inductors and switched capacitors to form an asymmetric boost converter structure, so that the voltage gain of the converter is more than twice that of the traditional coupled inductor boost converter; and it adopts the passive clamp circuit to eliminate the switch voltage spike at the moment of turn-off, so that the voltage stress and current stress on the switch devices are reduced. The simulation results show that the boost converter obtains high voltage gain and high efficiency, and is suitable for applications with large DC boost ratio.

Pseudo DC-Link EV Home Charger With a High Semiconductor Device Utilization Factor

This article proposes a bidirectional battery charger for grid to vehicle and vehicle to grid operations of electric vehicles (EV). The dc stage of the proposed converter offers a quadratic buck–boost voltage gain ratio, which makes it suitable for interconnecting the battery pack unit of EVs with both dc and ac grids as a home EV charger. A high-voltage gain ratio, low voltage, and current stress of switches, high values of utilization factors (UF) for both directions are achieved. Continuous input current and common electrical ground are preserved at the dc–dc stage and also, the continuous output current of the proposed converter makes the realization of the pseudo dc-link method possible for connecting to an ac grid. Consequently, the switching power loss in the dc–ac stage of the EV charger is reduced, and as a result, it allows the proposed charger to run more efficiently and cooler. The operating principle, steady-state characteristics including the current, voltage stress, and UF of the switches, and comparison with other state-of-the-art dc–dc bidirectional converters are carried out in detail. Finally, to verify the theoretical achievements, a 500-W laboratory prototype of the proposed EV charger is implemented. The EV charger exhibits the capability for ac and dc regulation and demonstrates peak efficiency of 97.8% in the forward and 97.5% in the backward direction modes of operation.

Analysis of Multi-Phase qZ-Source Inverter with Maximum Constant Boost Control Technique

This paper proposes a topology of two-level qZ- source multiphase inverter based on maximum constant boost control algorithm which can be used to power multiphase machines. Indeed, these kinds of machines have many advantages compared to their counterpart three-phase machines, which are actually used extensively in many industries. On the other side, the qZ-source inverter has also many advantages compared to the conventional inverters, mainly high boosting capability, more freedom degrees of switching states and less voltage and current stresses of switches can be obtained. Such advantages among others make it to be a good candidate in many industrial applications. Thus, the present paper proposes the topology of two level five-phase qZ-source inverter, where the main aim is to be used for driving the five-phase machine and consequently benefiting from the merits of the advantages of both topologies of the machine and the inverter in building one combined topology. The simulations results obtained in this paper prove the quality of the improved performances of the proposed topology in comparison with previous works which can be a promising solution in many industrial applications based on the afore mentioned advantages.

Hybrid Control Scheme for Photovoltaic Microinverter With Adaptive Inductor

This paper studies the two-stage photovoltaic microinverter. Its prestage is a full-bridge dc–dc converter with an adaptive inductor whose inductance can be regulated by a controlled current source. The aim of the adaptive inductor is to realize current boundary continuous mode (BCM) operation with constant frequency and decrease the current stress of the switches in the prestage converter. The structure and operational principle of the proposed adaptive inductor are introduced. The mathematical model has been established for achieving the proper inductance of the adaptive inductor for BCM operation and for verifying the operational condition of the core. The current stress of switches and power loss of the prestage converter with the adaptive inductor or the fixed inductor are analyzed. A hybrid control strategy, which includes an adaptive inductor regulating controller, discontinuous conduction mode operation, and BCM selection in different power ranges, is proposed according to the derived mathematical model. The experimental results are presented to verify the analysis.

A Versatile Family of Partial-Resonance Inductive-AC-Link Universal Converters

In this paper, a new class of bidirectional partial-resonance power converters is presented. The proposed family can be configured to interface single- or multi-port dc, single- or multi-phase ac systems at input-side and/or output-side. The proposed family offers a very modular structure, which can lead to cost reduction from a common designed module. In this converter, which accomplishes power conversion in a single stage, a small inductor placed in series with the input and output switch-bridges forms the link. This small link inductor is responsible for transferring power between different ports of the system. The proposed topologies can operate in buck, boost, and buck–boost modes of operation to step up and/or step down the voltage. In buck–boost mode of operation, the converter is controlled such that the power is entirely transferred through the link inductor; whereas, in buck or boost modes of operation only a fraction of the power is transferred through the link inductor, and the remaining power is directly transferred from input phases to the output phases. Galvanic isolation, which is typically a prominent factor contributing to power density of a converter, can be provided by means of a compact and lightweight single-phase high-frequency transformer added to the link. In comparison with earlier generations of partial-resonance inductive-link power converters, in the proposed converter, the level of link peak current and consequently power-loss, as well as voltage and current stress of switches are dramatically decreased. A very small film capacitor can be placed in parallel with the link inductor to facilitate zero-voltage-switching (ZVS) operation for all the switches/diodes. Apart from increasing the overall efficiency, minimized dv/dt stress and improvement in power density are achieved by adding the link capacitor. The proposed converter employs four-quadrant switches, i.e., bidirectional-conducting bidirectional-blocking switches, and charges the link inductor in both positive and negative directions in each cycle. In view of this, better utilization of the link inductor and lower total harmonic distortion (THD) are offered. Furthermore, two distinct switching algorithms are developed for the proposed family of converters. In this paper, the detailed behavior of the proposed family is investigated analytically, and simulation and experimental results are presented to evaluate the performance and effectiveness of the proposed converter. A low-power proof-of-concept prototype with input voltage of 59 V/161 V, load voltage of 178 V/73.5 V, maximum switching frequency of 4.9 kHz/3.65 kHz at 215 W/450 W in a step-up/step-down operation is considered for the experimental verification.

New high step‐up two‐input‐single‐output converter with low‐voltage stresses on switches and zero input currents ripple

This study proposes a new non-isolated high-step-up two-input-single-output DC–DC converter with the capability of cancelling input currents ripples. The proposed converter has low-voltage stresses on switches and diodes. Furthermore, it consists of two three-winding-coupled inductors connected with voltage multiplier cells. The voltage gain of the proposed converter can be increased by adding the second windings’ turns’ ratio or increasing the number of voltage multiplier cells. The third windings of coupled inductors, which are in series with capacitors at the input part of each boost stage are used to eliminate the ripples of input currents for the whole range of duty cycles. The proposed structure is a kind of two-phase converter that can be used as an interleaved converter with one-input-one-output terminals. In this study, the proposed converter is analysed during all operating modes and the voltage and current stresses of switches and diodes, voltage gain, required condition for cancelling input currents ripple are calculated. Moreover, in order to reconfirm theoretical analysis, EMTDC/PSCAD simulation and experimental results are presented.

A New Structure for Nonisolated Boost DC–DC Converter

In this paper, a new structure of nonisolated boost DC–DC converters is proposed. The operation of the proposed structure in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) is presented. Then, the critical inductance relation between CCM and DCM is obtained. The voltage gain and current stress of switches are calculated. Finally, the validity of the presented theoretical issues is reconfirmed by using simulation results obtained from PSCAD/EMTDC software.