Diode Losses Research Articles

An Analytical Evaluation of Performance Limit for PiN diodes and IGBTs

This paper reports analytical evaluation for minimum reverse recovery loss and turn‐off loss of PiN diodes and IGBTs, respectively. In this evaluation, we take account of structural parameters and current continuity at the both ends of the i‐layer, and we calculate switching losses (E) from energy dissipation on the i‐layer during switching action by using position integration instead of time integration. In the case of IGBT, we assume that depletion layer spreads from the i‐layer and n+ layer interface of the PiN diode that corresponds to bottom p type layer ‐ n− layer ‐ p type backgate region of IGBT cells. We evaluate optimum structure for minimum energy dissipation of these switching actions and conduction states by newly employed index RE consists of R calculated by voltage drop at the i‐layer and both ends of the i‐layer and E. We clarify that ideal carrier profile for minimum RE, and we also evaluate structural parameters for that condition. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

A new soft‐switching multi‐input quasi‐Z‐source converter for hybrid sources systems

This study focuses on a zero voltage transition multi-input quasi-Z-source converter (qZSC). This topology can be used for input sources with different voltages and currents to provide a constant output voltage. In the proposed structure, several qZSCs are combined and the output filter of all stages is eliminated. Therefore, the overall number of circuit elements, cost, volume and weight are reduced in comparison with when they are in a separate operation. In this converter, the soft-switching conditions are provided for all stages by using only one auxiliary circuit. The employed technique provides zero-voltage zero-current switching (ZVZCS) and zero-voltage switching for main switches at turn-on and turn-off instants, respectively. The auxiliary switch turns on under zero-current switching and turns off under ZVZCS. Furthermore, the reverse recovery losses of diodes are reduced. The theoretical foundation of the proposed converter is presented and its performance is simulated by OrCAD software. The obtained results show 3.5% improvement in the efficiency at nominal loads, compared to its hard-switching counterpart. A dual-input prototype of the proposed structure is successfully built to support the validity of the theoretical analysis.

A Single-Stage High Power Factor Power Supply for Providing an LED Street-Light Lamp Featuring Soft-Switching and Bluetooth Wireless Dimming Capability

Light-emitting diode (LED) has the characteristics of environmental protection and energy saving, having become the lighting source of a new generation of street-light lamps. The traditional two-stage power supply for providing an LED street-light lamp is composed of an AC-DC converter with a power-factor-correction (PFC) function at the front stage and a DC-DC converter at the rear stage. The two-stage power supply for an LED street-light lamp has a large number of electronic components and costs, and the circuit efficiency is not high. Therefore, this paper presents a novel single-stage high power factor AC-DC power supply for providing an LED street-light lamp featuring soft-switching and Bluetooth wireless dimming capability through using smart tablets or smartphones to remote control the output power of the LED street-light lamp for achieving energy-saving benefits. The proposed AC-DC LED power supply integrates an interleaved buck converter circuit with coupled inductors and a half-bridge LLC resonant converter circuit into a single-stage power conversion circuit. Moreover, the coupled inductor of the interleaved buck converter circuit is designed to operate in the discontinuous conduction mode, which can naturally achieve PFC. In addition, the two power switches in the novel LED power supply have zero-voltage switching (ZVS) characteristics, which can reduce the switching losses of the power switches. The two output diodes have the characteristics of zero-current switching (ZCS), which can reduce the conduction losses of the power diodes. This paper developed a single-stage prototype circuit for providing an 144 W (36 V/4 A)-rated LED street-light lamp. According to the experimental results of the prototype circuit with an AC input voltage of 110 volts, the presented single-stage LED power supply offers high power factor (PF > 0.99), low input-current total harmonic distortion factor (THD < 3%), and high efficiency (>89%). In addition, this paper used the built-in Bluetooth wireless communication function of a smart tablet or smart phone to fulfill remote dimming control. By changing the duty ratio of the control signal, we could realize remote dimming control of 20% to 100% of the output LED street-light lamp power.

Full Digital Control of an All-Si On-Board Charger Operating in Discontinuous Conduction Mode

This paper deals with the design, tuning and implementation of a digital controller for an all-Si electric vehicle (EV) on-board battery charger operated in discontinuous conduction mode (DCM). This charger consists of two cascaded conversion stages: a front-end power factor corrector (PFC) with two interleaved legs and an isolated phase-shifted full bridge DC/DC converter. Both stages operate in DCM over the complete battery charging power range, allowing lower inductance values for both the PFC and the DC/DC filtering elements. Moreover, DCM operation ensures a large reduction of the reverse-recovery losses in the power diodes, enabling the adoption of relatively cheap Si devices. The main goal of the work is to address the well-known DCM control challenges, leveraging a novel control strategy for both converter stages. This control scheme counteracts the DCM system non-linearities with a proper feed-forward contribution and an open-loop gain adjustment, ensuring consistent dynamical performance over the complete operating range. The designed controllers are tuned analytically, taking into account the delay components related to the digital implementation. Finally, the proposed control strategy is implemented on a single general purpose microcontroller unit (MCU) and its performance is experimentally validated on a 3.3 kW battery charger prototype.

Characterization of a 3.3-kV Si-SiC Hybrid Power Module in Half-Bridge Topology for Traction Inverter Application

A state-of-the-art 3.3-kV/450-A hybrid power module for the next generation traction inverter of rolling stock is reported in this paper, combining the silicon (Si) insulated-gate bipolar transistor (IGBT) and silicon carbide Schottky barrier diodes (SBDs) chips. Compared with the existing hybrid technology at the same voltage level, this module is characterized by a half-bridge topology, in which 6 IGBT and 12 SBD chips are integrated in each switch. The outnumbering of the diodes represents a promising mitigation to the low availability of SBDs at this voltage level. Both static and dynamic test of this module and an equivalent Si-based module are carried out comparatively. Apart from describing the features of compactness, low-inductance, and good current distribution among chips, this module is characterized by low turn-ON current overshooting and turn-ON loss of IGBTs, negligible diode reverse recovery time and loss, as well as flexible allowance of IGBT turnON current rising rate dI/dt. A parameterized study is carried out to benchmark the advantage of this new topology. Based on the experimental results, the performance of the hybrid module in a three-phase traction inverter circuit is also evaluated by means of electro-thermal simulation. The hybrid module distinguishes itself by describing much lower power loss and junction temperature than its Si-based counterpart.

Electrical properties of inhomogeneous tungsten carbide Schottky barrier on 4H-SiC

In this paper, the electrical behavior of tungsten carbide (WC) Schottky barrier on 4H-SiC was investigated. First, a statistical current-voltage (I–V) analysis in forward bias, performed on a set of equivalent diodes, showed a symmetric Gaussian-like distribution of the barrier heights after annealing at 700 °C, where a low Schottky barrier height (ΦB = 1.05 eV) and an ideality factor n = 1.06 were measured. The low value of the barrier height makes such a WC contact an interesting candidate to reduce the conduction losses in 4H-SiC Schottky diodes. A deeper characterization has been carried out, by monitoring the temperature dependence of the I–V characteristics and the behavior of the relevant parameters ΦB and n. The increase of the barrier height and decrease of the ideality factor with increasing temperature indicated a lateral inhomogeneity of the WC/4H-SiC Schottky contact, which was described by invoking Tung’s model. Interestingly, the temperature dependence of the leakage current under reverse bias could be described by considering in the thermionic field emission model the temperature dependent barrier height related to the inhomogeneity. These results can be useful to predict the behavior of WC/4H-SiC Schottky diodes under operative conditions.

High‐order high‐performance LCLCL DC/DC converter based on harmonic optimisation

This work presents a new type of high-order LCLCL resonant DC/DC converter. The converter in this study can properly inject the third harmonic for energy transmission through optimal configuration and parameter design of the resonant tank, which can not only achieve a wider voltage regulation range but also provide an easy method for soft start and overcurrent protection. In this study, both switches can realise soft switching, and due to the injection of the third harmonic, the loss of the secondary rectifier diode is reduced. This article describes the working principle of the LCLCL converter and provides the parameter design principle and small-signal modelling method. In the laboratory, a 400 W prototype with 400 V input and 24 V output is built to verify the correctness of the theoretical analysis.

Calculation of Semiconductor Power Losses of a Three-Phase Quasi-Z-Source Inverter

This paper presents two novel algorithms for the calculation of semiconductor losses of a three-phase quasi-Z-source inverter (qZSI). The conduction and switching losses are calculated based on the output current-voltage characteristics and switching characteristics, respectively, which are provided by the semiconductor device manufacturer. The considered inverter has been operated in a stand-alone operation mode, whereby the sinusoidal pulse width modulation (SPWM) with injected 3rd harmonic has been implemented. The proposed algorithms calculate the losses of the insulated gate bipolar transistors (IGBTs) and the free-wheeling diodes in the inverter bridge, as well as the losses of the impedance network diode. The first considered algorithm requires the mean value of the inverter input voltage, the mean value of the impedance network inductor current, the peak value of the phase current, the modulation index, the duty cycle, and the phase angle between the fundamental output phase current and voltage. Its implementation is feasible only for the Z-source-related topologies with the SPWM. The second considered algorithm requires the instantaneous values of the inverter input voltage, the impedance network diode current, the impedance network inductor current, the phase current, and the duty cycle. However, it does not impose any limitations regarding the inverter topology or switching modulation strategy. The semiconductor losses calculated by the proposed algorithms were compared with the experimentally determined losses. Based on the comparison, the correction factor for the IGBT switching energies was determined so the errors of both the algorithms were reduced to less than 12%.

Internal loss of AlGaN-based ultraviolet-B band laser diodes with p-type AlGaN cladding layer using polarization doping

Aluminum gallium nitride (AlGaN)-based ultraviolet-B band laser diodes (LDs) with a p-type AlGaN cladding layer using polarization doping were fabricated on lattice-relaxed Al0.6Ga0.4N/AlN/sapphire. The threshold current density Jth and lasing wavelength of this LD were 25 kA cm−2 and 298 nm, respectively. The internal loss (αi) was estimated by means of a variable stripe length method using optical excitation. The αi value of this LD was relatively low (i.e. <10 cm−1), thus suggesting that the device is characterized by both, proper light confinement and low internal loss.

Evolutionary Design Automation of High Efficiency Series Resonant Converter for Photovoltaic Systems

Series resonant converter (SRC) is one of the main parts which has to be designed carefully to be compatible with the general requirements of photovoltaic (PV) grid-connected system. The extensive search space for design parameters of SRC such as resonant tank component values, transformer turn ratio, dead time and switching frequency requires an automated design framework. The proposed framework is developed using genetic algorithm (GA), differential evolution algorithm (DEA), and nondominated sorting genetic algorithm (NSGA-II) for the multi-objective optimization of SRC circuit while accomplishing zero voltage switching (ZVS). Regulating the output voltage while minimizing the losses of MOSFET, diode and transformer are the design objectives. FEM is applied to subdivide the single phase transformer into simpler and finite parts to calculate flux density value according to the optimized design parameters. Amongst these evolutionary algorithms, NSGA-II achieved the best optimization performance considering various operation modes and required specifications. Simulation results are also provided to validate the efficient and robust automated design of SRC to be used in photovoltaic systems.

Coupled‐inductor‐based high‐gain converter utilising magnetising inductance to achieve soft‐switching with low voltage stress on devices

This work proposes a soft-switched quadratic quadrupler boost converter with high voltage step up gain and low voltage stress on devices. With this converter topology, high voltage gain is achieved at low duty ratio operation of MOSFETs and few number of turns in coupled inductor. Operation at low duty ratio keeps boost converter gain in linear region and smaller number of turns in coupled inductor reduces the lossy part of the winding. Further, the magnetising inductance of coupled inductor is utilised to achieve zero voltage switching of MOSFETs to minimise the switching loss. In addition, secondary side diodes are operating under zero current switching conditions using resonance between leakage inductance and the capacitors of voltage quadrupler circuit. This greatly reduces the reverse recovery losses of the secondary side diodes. A detailed analysis of converter dynamics is discussed in one of the subsections to find out small-signal transfer functions with respect to variations in input voltage and duty ratio variation of MOSFETs. A 250 W prototype of the proposed converter is built and tested in laboratory with a maximum efficiency of ∼93% at 175 W output power.

Passive Resonant Level Shifter for Suppression of Crosstalk Effect and Reduction of Body Diode Loss of SiC MOSFETs in Bridge Legs

Due to the presence of parasitic elements in switching devices and circuit realization, crosstalk phenomenon in bridge-leg configurations is unavoidable. A passive resonant level shifter that can suppress the effect of the crosstalk and deliver a low off-state gate-source voltage to reduce the forward voltage drop of the body diode of SiC mosfets is presented. The circuit is composed of two parts. The first one is a resistor-capacitor-diode (RCD) level shifter that delivers a static negative off-state gate-source voltage to the mosfets. The voltage level is designed to be close to zero, so that the forward voltage drop of the body diode is lowered. The second one is a series resonant tank circuit. It generates short voltage pulses to counteract the voltage pulses caused by the crosstalk. The gate-source voltage can then be maintained at a level below the threshold voltage of the mosfets. The proposed level shifter does not require any active devices or additional supply. It can be applied readily to commercially available gate drivers. A passive resonant level shifter module for four SiC mosfets in a 1-kW H-bridge inverter has been built and evaluated. Detailed performance comparison with the RCD level shifter will be given.

A Reduced-Switch-Count Family of Soft-Switched High-Frequency Inductive AC-Link Converters

This article introduces a new family of partial-resonance high-frequency ac-link converters with a reduced number of switches, which contributes to enhanced reliability and reduced size. The proposed family of converters can be configured to interface various number of single-/multiport dc and/or single-/multiphase ac systems of sources and loads through a partial-resonance parallel LC link. The LC link is composed of a small inductor and a very small ac capacitor without the use of bulky and short life-cycle electrolytic capacitors. The high-frequency ac link is responsible for transferring power between different ports of the system entirely or partially as well as realizing zero voltage switching for all the power switches/diodes over the full load range, which results in minimized stress over the switches as well as low electromagnetic interference (EMI). This class of converters, which only employs two-quadrant switches, is inherently bidirectional with voltage step-up/step-down capability. It allows variable frequencies and power factors between the input and output terminals in one stage of power conversion. The proposed converters can function in buck–boost, buck, and/or boost modes of operation to step up and/or step down the input voltage. Functioning in buck or boost modes of operation can significantly reduce the link peak current and voltage, contributing to reduced power loss, size of components, voltage/current stress of power switches/diodes, and EMI. Furthermore, the proposed converters are robust against the open-circuit/short-circuit problems of input, output, and link inductors/capacitors, which place emphasis on improved reliability of the system. They are also capable of minimizing poor recovery issues and related losses of the body diodes of switches by using external fast recovery diodes in series with the main switching devices. In view of these features, this class of converters is expected to exhibit improved reliability, efficiency, power density, functionality, and flexibility compared to most existing power converters. A current modulation approach is also developed for each function to regulate the input and output currents on a switching cycle-by-cycle basis. A detailed performance analysis to investigate the challenges of each function in terms of frequency, power factor, and voltage amplitude is presented. The effectiveness of the proposed configurations along with the modulation schemes is verified theoretically using simulation software and experimentally via a low-power laboratory prototype at different operating conditions.

A Flexible Mode Electrolytic Capacitor-Free LED Driver With High Efficiency Over a Wide Range of Input Voltage

The conventional ac-dc LED drivers fail to achieve high efficiency and optimized bus voltage over a wide range of input voltage. In order to obtain the better performance in high-line and low-line conditions simultaneously, a flexible mode LED driver is proposed. The proposed driver can operate in half-voltage input mode at high-line input to achieve relatively low-bus voltage and high efficiency. Meanwhile, the proposed driver can operate in full-voltage input mode at low-line input to cut down the diode loss and switch loss; thus, high efficiency can be also achieved. Meanwhile, zero-voltage switching characteristic of the active switches can be fulfilled in both modes. In addition, the proposed LED driver can achieve electrolytic capacitor free. The detail structure, operational principle, and design considerations are examined in detail. Finally, the feasibility and the effectiveness of the proposed LED driver are verified by an experimental prototype with rated power of 100 W.

Study of multimode semiconductor lasers with buried mesas

A buried-mesa AlGaAs/GaAs/GaInAs laser heterostructure emitting at a wavelength of 1050 nm is formed on a GaAs substrate by MOCVD. Mesa-stripe laser diodes with an aperture of 100 μm based on the obtained heterostructure are fabricated and studied. The internal optical losses of the laser diodes are 2.4 cm−1. The output powers in both directions achieved at a cavity length of 2900 μm in the cw and pulsed regimes were 2.1 and 23 W, respectively.

MOSFET Power Loss Estimation in LLC Resonant Converters: Time Interval Analysis

In the past ten years, LLC resonant converters have become a mainstream topology for dc/dc power conversion, and multiple design tools have been developed for this topology, including controllers, regulators, soft-switching techniques, etc. While many tools are available for designing this converter, techniques for accurately determining power losses in the inverter mosfet s of the topology based on time-domain analysis have not been fully explored yet. Precise power loss estimation is fundamental to determine the thermal behavior of the switches before the converter is built, which accelerates and optimizes the thermal management design process. In addition, accurate methods of estimating conduction losses, which are dominant in this topology, switching losses, and body diode losses are lacking in the literature. This paper proposes a method for enhancing power loss estimation in LLC inverter mosfet s based on time-domain analysis of the converter. Moreover, a detailed characterization of mosfet 's conduction losses ( $P_{\text{cond}}$ ), switching losses ( $P_{\text{sw}}$ ), and body diode losses ( $P_{\text{diode}}$ ), including the effects of different parameters such as gate-source voltage ( $V_{\text{GS}}$ ), junction temperature ( $T_{j}$ ), drain current ( $\displaystyle I_{D}$ ), and drain-source voltage ( $V_{\text{DS}}$ ), is presented, which can further improve power loss assessment in this topology. The developed method based on time interval analysis replaces the simplistic first-harmonic approximation (FHA), which allows for improved power loss calculations. Further improvement is obtained with the detailed characterization of the switching device. As verified by simulation and experimental results, the proposed estimation tool provides a significant boost in accuracy for power loss determination when compared to the existing method for power loss estimation using FHA.

Angular rotation ion implantation technology in SiC for 4H-SiC junction barrier Schottky rectifiers

• This study proposes an angular rotation ion implantation technology. • This technology could improve the rate of finished product products to be 90%. • With the angle rotation technology, the production cost will be saved effectively. SiC is widely used for making high level power electronic devices due to its excellent properties. SiC Junction Barrier Schottky (JBS) diodes have a low reverse leakage current and could offer fast switching and the Schottky-like on-state characteristics. High temperature ion implantation has been an essential process for the mainly doping formation SiC power electronic devices. In this work, the angular rotation ion implantation technology in SiC JBS has been investigated. The distribution of the injected elements has also been simulated, and the calculated results fitted well with the experimental results. With this angular rotation technology the power loss of the SiC JBS diodes have been reduced, effectively. And the rate of finished product was turned out to be as high as 90%. This method can greatly reduce the process flow, reduce the damage to the wafer and save production cost, which has great significance in quantity production.

KF‐based estimation of diode turn‐off power loss using datasheet information

In this Letter, an effective method for estimation of turn-off power losses of power diodes using datasheet information is proposed. An effective regression method with non-linear least-squares algorithm is used to obtain approximate representations of the reverse-recovery charge and softness factor of the diode using datasheet information. Kalman Filter (KF) algorithm is then used to accurately acquire the value of diode forward current at the turn-off instant. Finally, the obtained information is used to estimate the turn-off power losses with simple calculations, based on approximated reverse-recovery equations. Despite the simplicity of the proposed technique, the results demonstrate that the estimation error does not exceed 4% in the worst case.

Development of two-phase interleaved synchronous rectification DC-DC for commercial vehicle engine ECU

The commercial vehicle diesel engine ECU and the electronically controlled common rail system power supply developed in this paper adopt the two-phase BUCK converter as the main loop. Considering the problems of large current fluctuation, high continuum diode loss and possible non-uniform current in parallel connection of traditional BUCK converter, a control strategy of two-phase staggered parallel synchronous rectifier BUCK converter is proposed. The relationship between current fluctuation and inductance, switching frequency and duty cycle of different operating modes is theoretically analyzed, and the current fluctuation of traditional BUCK converter is compared. The prototype test results show that the converter structure and control strategy effectively reduce the output current fluctuation and improve the system power density.

Resonant Converter with Soft Switching and Wide Voltage Operation

A new DC/DC resonant converter with wide output voltage range operation is presented and studied to have the benefits of low switching losses on active devices and low voltage stresses on power diodes. To overcome serious reverse recovery losses of power diodes on a conventional full-bridge pulse-width modulation converter, the resonant converter is adopted to reduce the switching loss and increase the circuit efficiency. To extend the output voltage range in conventional half-bridge or full-bridge resonant converters, the secondary sides of two diode rectifiers are connected in series to have wide output voltage operation. The proposed converter can be either operated at one-resonant-converter mode for low voltage range or two-resonant-converter mode for high voltage range. Thus, the voltage rating of power diodes is decreased. Experiments with the design example are given to show the circuit performance and validate the theoretical discussion and analysis.