Anti-parallel Diode Research Articles

Soft-Switching High Step-Up/Down Bidirectional DC–DC Converter

A nonisolated bidirectional dc-dc converter with high voltage gain, low voltage stress, low component count, and soft-switching features is presented in this paper. In this topology, coupled inductors and voltage multiplier cells are merged to achieve high step-up/down voltage gain. Also, due to using active clamp circuits, the voltage stress of power switches is relatively low. Thus, the low voltage switches with low on-resistance can be employed to reduce the conduction losses. Furthermore, zero-voltage switching is accomplished in both high step-up and high step-down modes for all power switches, and due to zero-current switching operation of all antiparallel diodes, the reverse recovery losses are reduced. In order to verify the theoretical analysis and the converter performance, a 200 W prototype circuit of the proposed converter is implemented in the laboratory.

Multi-Input Ćuk-Derived Buck-Boost Voltage Source Inverter for Photovoltaic Systems in Microgrid Applications

This paper presents a multi-input Ćuk-derived Buck-Boost voltage source inverter (CBBVSI) for Photovoltaic (PV) systems. The proposed topology consists of a single-stage DC-AC inverter that combines both DC-DC and DC-AC stages. The DC-DC stage is used for stepping-up the voltage from the PV generator. Simultaneously, the DC-AC stage is used for interfacing the PV source with the AC grid. The topology allows three sources to utilize the antiparallel diodes for each inverter leg for transferring the energy. The proposed system exhibits several features such as a reduction of the number of components compared to typical two-stage structures, and Split-Source Inverter (SSI), and Z-Source Inverter (ZSI) topologies. Moreover, the power of each PV source can be harvested either simultaneously or separately since independent Maximum Power Point Tracking (MPPT) is performed. The system was simulated using MATLAB/SIMULINK software and a 1 kW laboratory prototype was implemented to verify the operation of the proposed CBBVSI. The numerical simulations are presented together with the experimental results, showing a good agreement.

Frozen Leg Operation of a Three-Phase Dual Active Bridge Converter

Three-phase dual active bridge (DAB) topology is a potential alternative for high-power applications when a compact and efficient converter with a bidirectional power transfer capability is desired. In a constructed prototype, high-power SiC modules with dedicated drivers are utilized to achieve high-efficiency and compact size. Each module has two interconnected switches with anti-parallel diodes resembling a converter leg. It is observed that the driver halts the module operation as a result of protective actions such as overcurrent, gate undervoltage, or gate overvoltage. In this frozen leg mode, the module operates as a leg with two diodes until an external hardware signal resets the driver. The converter continues operation but with a reduced performance. Analysis, simulation, and verification of a three-phase DAB converter under a frozen leg operation are considered in this paper. The converter with a frozen leg has two different behaviors at light loads and heavy loads. Consequently, two different analysis methods are developed to solve converter operation in different load conditions. Results show that the power transfer capability is reduced, but this fault mode is nondestructive.

A broadband 630–720 GHz Schottky based sub-harmonic mixer using intrinsic resonances of hammer-head filter

An room temperature low noise anti-parallel Schottky diode based 630–720GHz sub-harmonic mixer (SHM) is designed, built and measured. Intrinsic resonances in low-pass hammer-head filter have been adopted to prevent the LO and RF power leak from the IF channel, while greatly minimizing the transmission line size. The mixer consists of 15um quartz terahertz circuit and 127um Al2O3 IF transformer circuit. An improved lumped element equivalent noise model of SBDs guarantees the accuracy of simulation. The measurement indicates that with local oscillating (LO) signal of 2–8 mW, the lowest double sideband (DSB) conversion loss is 8.2 dB at 645 GHz, and the best DSB noise temperature is 2800 K at 657GHz. The 3 dB bandwidth of conversion loss is 75 GHz from 638 to 715 GHz. The work IF frequency band is above 20GHz ranging from 1 to 20 GHz with −10dB return loss.

A Modified DC Chopper for Limiting the Fault Current and Controlling the DC-Link Voltage to Enhance Fault Ride-Through Capability of Doubly-Fed Induction-Generator-Based Wind Turbine

A simple conventional dc chopper is employed to protect the doubly-fed induction generator (DFIG) from overvoltage; however, it is not capable to keep the transient overcurrent in an acceptable level in stator and rotor sides. Therefore, an effective current-limiting strategy should be incorporated with the dc chopper to improve the fault ride-through capability of the DFIG. In this paper, a modified DC chopper is proposed not only to keep the dc-link voltage in an acceptable range, but also to limit the high-current level in the stator and the rotor sides in a permissible level without incorporating any extra fault-current-limiting strategy. Unlike the conventional dc chopper, in the proposed dc chopper, it is not required to stop rotor-side converter (RSC) switching and employ high-rated-current antiparallel diodes. The proposed modified dc chopper is placed between the dc-link capacitor and the RSC. In the proposed switching strategy of the modified dc chopper, three extra semiconductor switches are included, which are triggered to insert dc chopper resistance either in parallel or series connections with the dc link regarding the dc-link voltage level and the dc-link current level, respectively. Calculation of the dc chopper resistance is discussed. To prove the effectiveness and robustness of the proposed modified dc chopper in terms of both limiting the fault current and controlling the dc-link voltage of the DFIG, symmetrical and asymmetrical grid faults are applied in a power system including the DFIG-based wind turbine modeled in PSCAD/EMTDC so.

Nonlinear effect of forced harmonic oscillator subject to sliding friction and simulation by a simple nonlinear circuit

We study the nonlinear behaviors of mass-spring systems damped by dry friction using simulation by a nonlinear LC circuit damped by anti-parallel diodes. We show that the differential equation for the electric oscillator is equivalent to that of the mechanical system when a piecewise linear model is used to simplify the diodes' I–V curve. We derive series solutions to the differential equation under weak nonlinear approximation which can describe the resonant response as well as amplitudes of superharmonic components. The experimental results are consistent with the series solutions. We also present the phenomenon of hysteresis. A theoretical analysis along with numerical simulations is conducted to explore the stick-slip boundary. The correspondence between the mechanical and electric oscillators makes it easy to demonstrate the behaviors of this nonlinear oscillator on a digital oscilloscope. It can be used to extend the linear RLC experiment at the undergraduate level.

A Snapback-Free and Low Turn-Off Loss Reverse-Conducting SOI-LIGBT With Embedded Diode and MOSFET

A novel snapback-free and low turn-off loss reverse-conducting (RC) SOI-LIGBT is proposed and investigated by numerical simulations. An n-MOSFET (MN2) is embedded in the anode side of the LIGBT to short the P-anode/N-buffer junction during the turn-off transient, thus allowing the LIGBT to be turned off rapidly without excessive tail current. In addition, MN2 enable the LIGBT to conduct the reverse conducting current like the freewheeling diode. In the forward-conducting state, MN2 is turned off, then the proposed LIGBT operates like a conventional one and the snap-back is avoided. The gate electrode of MN2 can be controlled synchronously by the gate signal of the LIGBT which is level-shifted by a p-i-n diode (D1) and processed by an anode-controlling circuit, and therefore, the proposed RC-LIGBT still maintains a three-terminal configuration. D1 and MN2 are embedded in the drift region and anode-side of the LIGBT, respectively, and they can be isolated by deep-oxide trenches. The numerical simulation results reveal that the turn-off loss ( ${E} _{\mathrm{ off}}$ ) and reverse recovery charge of the proposed LIGBT is reduced by 58.3% and 38.9%, respectively, compared with the conventional LIGBT combining with antiparallel freewheeling diode.

A Snapback-Free and Low-Loss RC-IGBT With Lateral FWD Integrated in the Terminal Region

A novel Reverse Conduction Insulated Gate Bipolar Transistor (RC-IGBT) with Lateral Free-Wheeling Diode (FWD) integrated in the Termination is proposed and investigated by simulation, named LDT-RC-IGBT. Firstly, the Equi-Potential Ring (EPR) of the termination acts as an anode and the N-Stopper/N-Collector of the termination acts as the cathode of the anti-parallel built-in diode. The N-Stopper/N-Collector is shorted to the P-Collector, and it also acts as the electric filed stopper in the breakdown state. Secondly, the N-Collector and the P-Collector are designed apart at the surface and bottom, respectively. Thus the short effect of the N-Collector of the conventional RC-IGBT is avoided, and the snapback is completely eliminated. Thirdly, the P-Collector is not replaced by the N-Collector so that the hole injection is much higher than the conventional RC-IGBT, thus the forward voltage drop ( $V_{on}$ ) can be reduced remarkably, which is favorable to the decrease of conducting energy loss. The results show that, the LDT-RC-IGBT not only eliminates the snapback but also reduces $V_{on}$ , it achieves a better trade-off between $V_{on}$ and turn-off loss $E_{off}$ . At the same $V_{on}$ of 1.27 V, the $E_{off}$ of LDT-RC-IGBT is 2.06 mJ/cm2, which is 35.2%, 45.2% and 46.3% lower than that of the conventional RC-IGBT(3.19 mJ/cm2), TPRC-IGBT(3.78 mJ/cm2) and DARC-IGBT(3.85 mJ/cm2), respectively. At the same $E_{off}$ of 3.10 mJ/cm2, the $V_{on}$ of LDT-RC-IGBT is 1.17 V, which is 10% and 15.8% lower than that of the conventional RC-IGBT(1.30 V) and the DARC-IGBT(1.39 V), respectively.

A novel center-tapped transformer based multilevel inverter with common DC source

In this paper, a novel multilevel inverter topology is proposed which uses lesser switches and anti-parallel diodes are eliminated in the circuit configuration of the multilevel inverter. Optimal switching strategy for the inverter using three different Space Vector Pulse Width Modulation (SVPWM) techniques is analyzed based on the power quality indices. The proposed model is simulated and tested using MATLAB/Simulink. Owing to the switching techniques used the harmonic content at the output of the inverter is mitigated which results in a lesser value of total harmonic distortion. Reduced number of power electronic switches results in lesser power loss. The performance of the proposed system is validated with simulation results of conventional multilevel inverters and pulse width modulation control methods. The results for various performance parameters such as efficiency, switching loss, voltage magnitude, and total harmonic distortion are analyzed.

Reversals of period doubling, coexisting multiple attractors, and offset boosting in a novel memristive diode bridge-based hyperjerk circuit

In this paper, a new memristive diode bridge-based RC hyperjerk circuit is proposed. This new memristive hyperjerk oscillator (MHO) is obtained from the autonomous 4-D hyperjerk circuit (Leutcho et al. in Chaos Solitons Fractals 107:67–87, 2018) by replacing the nonlinear component (formed by two antiparallel diodes) with a first order memristive diode bridge. The circuit is described by a fifth-order continuous time autonomous (‘elegant’) hyperjerk system with smooth nonlinearities. The dynamics of the system is investigated in terms of equilibrium points and stability, phase portraits, bifurcation diagrams and two-parameter Lyapunov exponents diagrams. The numerical analysis of the model reveals interesting behaviors such as period-doubling, chaos, offset boosting, symmetry recovering crisis, antimonotonicity (i.e. concurrent creation and destruction of periodic orbits) and several coexisting bifurcations as well. One of the most attractive features of the new MHO considered in this work is the presence of several coexisting attractors (e.g. coexistence of two, three, four, five, six, seven, or nine attractors) for some suitable sets of system parameters, depending on the choice of initial conditions. Accordingly, the distribution of initial conditions related to each coexisting attractor is computed to highlight different basins of attraction. Laboratory experimental measurements are carried out to verify the theoretical analysis.

Accurate Estimation of Diode Reverse-Recovery Characteristics From Datasheet Specifications

This letter proposes a structured approach for accurate estimation of diode reverse-recovery characteristics using datasheet specifications. Considering a conductance model of a diode, the entire reverse-recovery process is divided into four operating modes. The state equations for each mode are derived taking the circuit nonidealities, viz., device capacitance and parasitic inductances, into account. Analytical expressions for reverse-recovery charge, reverse-recovery time, and diode current are derived and numerically solved to estimate the diode conductance directly from manufacturer's data. An empirical model is proposed to characterize the effects of temperature variation on the diode conductance. Numerical simulation and experimental results are presented for antiparallel diodes of three MOSFETs having different current and voltage ratings and also for a discrete p-n diode at different junction temperatures. The maximum estimation error with the proposed approach is 5.1% for peak reverse-recovery current and less than 8% for reverse-recovery time, peak voltage, and energy loss.

Low conversion loss and high isolation harmonic mixer based on multilayer graphene

Low conversion loss (CL) and high isolation graphene harmonic mixer with inductor-capacitor resonators and microstrip reflective stubs (MRS) is presented in this paper. The nonlinear electromagnetic field characteristics of the multilayer graphene are similar to those of an antiparallel diode pair, which has very strong nonlinear characteristic and is suitable for the development of the Low-level even-combinatorial-frequency harmonic mixer. Through the reflection of radio frequency (RF) signal and local oscillator (LO) frequency signal, the CL of graphene harmonic mixer is significantly reduced, and the isolation between the ports is also improved. The measured minimum CL at the LO power of 16dBm is about 19.2dB, and 2-3dB lower than that without MRS over the frequency band from 2.05-2.5GHz, while the isolation between ports is better than 30dB.

Threshold voltage instability in SiC MOSFETs as a consequence of current conduction in their body diode

An antiparallel PiN diode is present in the structure of the SiC Power MOSFET. For simplicity, increased module current ratings, and cost reasons, it sometimes may be preferable to use this diode rather than to add an external Schottky diode to the MOSFET. However, SiC PiN diodes are sensitive to defects in the SiC crystal, and their performance can degrade rapidly.In this paper, we assess the effect of several stresses on the characteristics of a SiC MOSFET, focusing on the stresses which involve the body diode. We demonstrate that using the body diode does not degrade its performances. However, it may produce a noticeable shift in the threshold voltage of the MOSFET. While this behaviour is observed for MOSFETs from one manufacturer, it is not exhibited for others, which indicates that it may be a consequence of some particular design or manufacturing parameters.

Design and Analysis of a New Zero Current Transition Bidirectional DC-DC Converter for Energy Storage Systems

This paper proposes a new zero-current transition based non-isolated bidirectional DC-DC converter for battery storage appliances in DC traction vehicles. The proposed converter has an auxiliary IGBTS, auxiliary inductor, auxiliary capacitor and bypass diodes are additionally to the main converter module. Usually, the zero-current transition achieved for the main IGBTs circuit has major advantages like reduced turn-off losses, overall conduction losses and minimized reverse recovery problems to the anti-parallel diodes of the main IGBTs. The operation principles, simulation and experimental investigations on 150 V/250 V/1 kW laboratory prototype are presented in order to show the performance and also to verify the soft-switching characteristics in boost/buck modes of the converter.DOI: http://dx.doi.org/10.5755/j01.eie.24.4.21471

A Developed Two-Leg Ladder Multilevel Converter Structure

The applications of multilevel converters (MCs) in industry have been increased because of their advantages such as high quality output waveform and lower harmonic distortions. This paper proposes an improved two-leg ladder topology for MC. For generating all levels at output voltage waveform, two methods are investigated for selecting the values of dc sources. The suggested structure generates a large number of levels at output voltage waveform with the least number of power electronic components such as insulated gate bipolar transistors, gate driver circuits, dc voltage sources and anti-parallel diodes in comparison with other similar topologies. Also, the magnitude of blocked voltage by switches is low. Power losses analysis on the proposed topology is provided. It is shown that the number of on-state switches in the presented structure is less than other similar topologies, which causes the voltage drop and power losses of proposed topology to be reduced. To show the merits of the proposed structure, comparison results are provided with other structures. To validate the analytical results of proposed topology, an experimental work for a 9-level converter and the simulation results for a 25-level converter are provided. PSCAD/EMTDC software is used for simulation works.

Quasi-resonant DC-Link transformer-less structures for grid-connected PV systems

This paper presents the quasi-resonant DC-Link transformer-less structures whereby the efficiency of the grid-connected PV systems could be improved. Transformer-less PV inverters as a critical part in power conditioning units are more advantageous to the user. However leakage current that is resulted from omitting bulky transformers can compromise their higher efficiency. So the low leakage current and high efficiency are two crucial points in transformer-less PV systems. By incorporating Quasi-resonant DC-Link as a method of soft switching into the H6 structures two new DC-decoupled soft-switched transformer-less PV inverters are proposed by which the switching losses of power devices as well as high di/dt, dv/dt and EMI could be avoided. A new auxiliary circuit is extracted from available structures. Proposed auxiliary circuit features lower voltage stress and saves one gate drive circuitry as well. Using only two auxiliary switches, ZVS turn on/off for high frequency DC bus switches and ZVS turn on/off of the antiparallel diodes of all grid frequency main switches are realized. Soft switching condition for auxiliary switches and their antiparallel diodes are also provided. Finally a 20 kHz 1-kW universal prototype is built and Operation characteristics, soft switching conditions and efficiency improvement of proposed QRDCL transformer-less PV inverters are verified.

DC-Link Current and Voltage Ripple Analysis Considering Antiparallel Diode Reverse Recovery in Voltage Source Inverters

In this paper, a method is proposed to investigate the dc-link current and voltage ripple calculations in voltage source inverters by considering the reverse recovery of the antiparallel diodes. The impact of the diode reverse recovery transient on the dc-link current and voltage within the switching period is first analyzed. The analysis indicates that the current ripple rms value is affected by the value of inverter switching frequency, diode reverse recovery time, and current. However, the diode reverse recovery shows negligible impact on the dc-link voltage ripple calculation, since the difference between the voltage ripples calculated by the proposed and existing method is less than 1%. To evaluate the estimation accuracy of the dc-link current ripple rms value by the proposed method, the experiments are implemented and the comprehensive analysis is done under different operating conditions, including various power factors, modulation indexes, inverter output currents, and inverter switching frequencies. Experimental results show that the accuracy of dc-link rms current ripple calculation by the proposed method is in the range of $\pm$ 5% and increased by up to 7% compared with the existing method neglecting the antiparallel diode reverse recovery.

Accurate Transient Calorimetric Measurement of Soft-Switching Losses of 10-kV SiC mosfets and Diodes

The characterization of soft-switching losses (SSL) of modern high-voltage SiC mosfet s is a difficult but necessary task in order to provide a sound basis for the accurate modeling of converter systems, such as medium-voltage-connected solid-state transformers, where soft-switching techniques are employed to achieve an improved converter efficiency. Switching losses (SL), in general, are typically measured with the well-known double pulse method. In the case of SSL measurements, however, this method is very sensitive to the limited accuracy of the measurement of the current and voltage transients, and thus is unsuitable for the characterization of fast-switching high-voltage mosfet s. This paper presents an accurate and reliable calorimetric method for the determination of SSL using the example of 10-kV SiC mosfet modules. Measured SSL curves are presented for different dc-link voltages and switched currents. Furthermore, a deeper analysis concerning the origin of SSL is performed. With the proposed measurement method, it can be experimentally proven that the largest share of the SSL arises from charging and discharging the output capacitance of the mosfet module and especially of the antiparallel junction barrier Schottky diode.

Remerging Feigenbaum trees, and multiple coexisting bifurcations in a novel hybrid diode-based hyperjerk circuit with offset boosting

This paper proposes a novel chaotic hyperjerk circuit obtained from the autonomous 4-D hyperjerk circuit (Leutcho et al. in Chaos Solitons Fractals 107:67–87, 2018) via substituting the nonlinear component (pair of anti-parallel diodes) with a first order hybrid diode circuit. The nonlinear component (i.e. hybrid diode) is characterized by a frequency dependent nonlinear I–V characteristic which is responsible for complex behaviours of the whole circuit. The essential dynamic properties of the model are investigated by exploiting numerical tools of nonlinear theory such as bifurcation diagrams, graphs of Lyapunov exponents, as well as phase portraits. Some interesting features are found including period-doubling bifurcation, coexisting bifurcations, symmetry recovering crises, antimonotonicity, and offset-boosting. One of the most interesting features of the new hyperjerk circuit is the presence of various areas of parameter space in which the hyperjerk system exhibits the attractive and intricate property of coexisting bifurcation and several coexisting attractors (e.g. coexistence of two, three, four, five, six, or seven disconnected periodic and chaotic attractors) for the same parameter’ set. Laboratory experimental results show a very good agreement with the theoretical analysis.

Switching-Cell Arrays—An Alternative Design Approach in Power Conversion

The conventional design of voltage-source power converters is based on a two-level half-bridge configuration and the selection of power devices designed to meet the full application specifications (voltage, current, etc.). This leads to the need to design and optimize a large number of different devices and their ancillary circuitry and prevents taking advantage from scale economies. This paper proposes a paradigm shift in the design of power converters through the use of a novel configurable device consisting on a matrix arrangement of highly optimized switching cells at a single voltage class. Each switching cell consists of a controlled switch with antiparallel diode together with a self-powered gate driver. By properly interconnecting the switching cells, the switching-cell array (SCA) can be configured as a multilevel active-clamped leg with a different number of levels. Thus, the SCA presents adjustable voltage and current ratings, according to the selected configuration. For maximum compactness, the SCA can be conceived to be only configurable by the device manufacturer upon the customer needs. For minimum cost, it can also be conceived to be configurable by the customer, leading to field-configurable SCAs. Experimental results of a 6 × 3 field-configurable SCA are provided to illustrate and validate this design approach.