Power Electronics Applications Research Articles

Dual Control Strategy for Non-Minimum Phase Behavior Mitigation in DC-DC Boost Converters Using Finite Control Set Model Predictive Control and Proportional–Integral Controllers

Model Predictive Control (MPC) has emerged as a promising alternative for controlling power converters, offering benefits such as flexibility, simplicity, and rapid control response, particularly when short-horizon algorithms are employed. This paper introduces a system using a short-horizon Finite Control Set MPC (FCS-MPC) strategy to specifically address the challenge of non-minimum phase behavior in boost converters. The non-minimum phase issue, which complicates the control process by introducing an initial inverse response, is effectively mitigated by the proposed method. A Proportional–Integral (PI) controller is integrated to dynamically adjust the reference current based on the output voltage error, thereby enhancing overall system stability and performance. Unlike conventional PI-MPC methods, where the PI controller has an influence on the system dynamics, the PI controller in this approach is solely used for tuning the reference current needed for the FCS-MPC controller. The PI controller addresses small deviations in output voltage, primarily due to model prediction inaccuracies, ensuring steady-state accuracy, while the FCS-MPC handles fast dynamic responses to adapt the controller’s behavior based on load conditions. This dual control strategy effectively balances the need for precise voltage regulation and rapid adaptation to varying load conditions. The proposed method’s effectiveness is validated through a multi-stage simulation test, demonstrating significant improvements in response time and stability compared to traditional control methods. Hardware-in-the-loop testing further confirms the system’s robustness and potential for real-time applications in power electronics.

Evaluation of an Infinite-Level Inverter Operation Powered by a DC–DC Converter in Open and Closed Loop

This paper evaluates the open- and closed-loop DC–DC converter operation within a DC coupling multilevel inverter architecture to obtain an infinite-level stepped sinusoidal voltage. Adding a cascade controller to the DC–DC converter should reduce the settling time and increase the number of levels in the output voltage waveform; it could decrease the speed error and phase shift concerning the sinusoidal reference signal. The proposed methodology consists of implementing an experimental multilevel inverter with DC coupling through a single-phase bridge inverter energized from a BUCK converter. Trigger signals for the two converters are obtained from a control circuit based in an ATMEGA644P microcontroller to explore its capabilities in power electronics applications. A digital controller is also implemented to evaluate the operation of the BUCK converter in open and closed loop and observe its influence in the stepped sinusoidal output voltage. The evaluation is performed to energize a resistive load with common output voltage in multilevel inverters, i.e., 3, 5, 7, 11, and infinity levels. Results show that during the design stage, fast dynamic elements, like the storage capacitor, can be used to obtain a minimum THD because the settling time is sufficiently fast, the speed error remains small, and there is no need for a controller. A digital controller requires processing time, and although in theory it can reduce the settling time to a minimum, the processor introduces latency in the control signals generation, producing the opposite effect. Controller complexity of the digital controller must be considered because it increases processing time and influences the efficiency of the closed-loop operation.

Germanium surface segregation in highly doped Ge:β-Ga2O3 grown by molecular beam epitaxy observed by synchrotron radiation hard x-ray photoelectron spectroscopy

We present a study of Ge segregation at the surface of highly germanium-doped gallium oxide (2.5 × 1020 cm−3 nominal doping level) grown by molecular beam epitaxy. We probed the dopant concentration as a function of depth by hard x-ray photoelectron spectroscopy and standard laboratory photoemission spectroscopy. We notably found that there is germanium segregation within the top 2 nm where its concentration is 3 times the nominal doping level. This increased dopant concentration leads to a threefold enhancement of surface conductivity. The results suggest a reliable method for delta doping for power electronics applications.

Novel super stack passivation in AlGaN/GaN HEMT for power electronic applications

Abstract A super-stack passivation technique is proposed for an AlGaN/GaN HEMT in order to improve the breakdown voltage and cutoff frequency. The performance of the proposed technique is benchmarked against a conventional GaN HEMT. The analysis and investigation are carried out using Technology Computer-Aided Design (TCAD). The simulation results are validated with experimental data. It is observed that the breakdown voltage of the conventional and proposed devices is 356V and 449V, respectively. In contrast to the conventional device, the breakdown voltage of the proposed device is improved by 21%. This is the manifestation of the suppression of the electric field by the super-stack passivation technique in the proposed device. Furthermore, it is also observed that the Johnson’s figure of merit in the proposed GaN-HEMT is also improved.

Phase disposition PWM control topology based: A novel multilevel inverter with reduced switch for power electronics applications

In the field of industrial drive applications, a neutral point clamped multilevel inverter (NPC MLI) is an extensively used option. The NPC MLI architecture involves more number of components for higher level and higher switching frequency operation. In this work paper, a novel three-phase 3-Level MLI is proposed evading the usage of clamping diodes and quadratic switches. Additionally, phase disposition pulse width modulation (PD-PWM) control technique is also employed for the proposed MLI. In comparison to NPC MLI, proposed MLI reduces the voltage switching stress as only one switch is operated per inverter leg. Another feature is that there is a considerable reduction in power losses as the current flows only through fewer elements. The proposed 3L inverter topology is explored thoroughly using the MATLAB simulation model. The evaluation of results is also demonstrated concerning the proposed PD-PWM technique by comparing its performance with the conventional sinusoidal PWM method. The Real-Time hardware-in-loop (HIL) simulator is also used to validate the simulation outcomes of the proposed model.

Fast switching Ga2O3 Schottky barrier power diode with beveled-mesa and BaTiO3 field plate edge termination

Power devices rely on ideal edge termination to suppress the electric field crowding and avoid premature breakdown before the material's critical field is reached. In this work, a hybrid electric field management configuration, featuring the combination of beveled-mesa (BM) termination and high-k oxide BaTiO3 field plate (FP), was implemented in Ga2O3 Schottky barrier diodes (SBDs). This BMFP-SBD realizes a breakdown voltage (BV) of 1.7 kV with extremely low reverse leakage current, outperforming the BM terminated SBD with BV of 0.64 kV and bare SBD with BV of 0.22 kV. Based on the temperature-dependent reverse characteristics, the dominant leakage mechanism transforms from Poole–Frenkel (P–F) emission in BM-SBD to variable-range-hopping (VRH) in BMFP-SBD at high bias. In particular, under switching conditions of di/dt up to 420 A/μs, the BMFP-SBD exhibits superior dynamic switching characteristics with a short reverse recovery time of 10.1 ns, which are comparable with those in advanced commercial SiC SBDs. These findings underscore the potential of Ga2O3 SBD enabled by BM and high-k FP edge termination for high-speed and high-voltage power electronics applications.

Sinusoidal PWM Generation for 3 Phase Inverter and RPM Measurement using Hercules TMS570LC43xx Launchpad

This project focuses on implementing a 3 phase Sinusoidal PWM generation using the Hercules TMS570LC43xx Launchpad Development Kit (Launchpad). The primary objective is to generate synchronized Sinusoidal nature PWM signals using the onboard High-End Timer (HET) and Enhanced Pulse Width Modulation (ePWM) module, which can be given to the Inverter for conversion of Direct current (DC) power into Alternating current (AC) power. This conversion is essential in various applications where AC power is required but the power source provides DC power. It is used in Solar photovoltaic (PV) systems and other renewable energy installations. These systems generate power suitable for powering household appliances or feeding into the electrical grid. Itis alsoused in electric vehicles (EVs) to drive the electric motor with variable speed. For verification of the wave nature, we have used an external lowpass filter (LPF) to transform the dynamic PWM signals into sinusoidal waveforms, ensuring compatibility with various applications like Inverters which can be further used in equipment and machinery such as Brushless DC motors, pumps and compressors. With the addon functionality to control the signal’s frequency which will be given to the Inverter to control the speed of the motor. Additionally, the project incorporates RPM measurement of the motor using an optical encoder setup interfaced with the Enhanced Quadrature Encoder Pulse (eQEP) module on the Launchpad. This feature enables accurate measurement of rotational speeds, position and Revolution per minute (RPM), enhancing the functionality of the system in real world applications like the speed of conveyor belts and other automated transport systems. Through successful implementation, this project demonstrates wide control for the Inverter, achieving reliable synchronized 3 phase signals with its variable speed having 120-degree phase shift signals alongside precise RPM measurement. The project highlights the Launchpad’s capabilities in handling complex signal processing tasks essential for modern power electronics applications. Looking forward, this project establishes a foundation for future enhancements and innovations in power electronics.

Design optimization for enhancing performances of integrated planar inductor for power electronics applications

Goal. In this work, the performance of an integrated planar inductor with a square geometric shape using different materials for the substrate: Ni-Fe, Mn-Zn and Ni-Zn have been analyzed and investigated in order to assess the impact of the substrate material on the performance of the integrated planar inductor and to determine the optimal material in the various applications of power modules in power electronics. Methods. To this end, we carried out an in-depth analysis of the geometric dimensions of the integrated planar inductor, by calculating all the geometric parameters of the proposed structure, to establish an equivalent physical model of the integrated planar inductor in order to evaluate its different electrical specifications. The numerical simulation, based on the three-dimensional mathematical model of the system using Maxwell’s equations, was realized by COMSOL Multiphysics software. Results show the importance of the substrate material for the performance of the integrated planar inductor, and specify that the use of Ni-Fe ferrite as a substrate of the integrated planar inductor gives very interesting performance compared to other materials studied. The presented results provide valuable information on the influence of substrate material on the performance of embedded integrated planar inductor and can help to design and optimize these components for use in power electronic systems. Practical value. These results are significant for a wide range of applications, where the integrated planar inductor performance and efficiency can have a significant impact on the overall performance and cost-effectiveness of the power electronic device. References 37, tables 2, figures 7.

Design and implementation of a solar power optimizer for module level power electronics application

AbstractPartial shading on series‐connected photovoltaic (PV) panels in conventional PV systems results in lower harvested power. To resolve this, it is vital to utilize module level power electronics (MLPE) such as Solar Power Optimizers (SPOs). This paper introduced a non‐isolated common ground non‐inverting output voltage buck‐boost converter as an SPO. Proposed converter benefits from continuous input and output currents which has a significant role in designing SPOs. Having a quadratic gain, beside acceptable step‐down range are other features of the converter. Operating principle, design, steady‐state, small‐signal analysis, and dynamic performance of proposed converter are included. Proposed converter is compared with other buck‐boost converters in terms of voltage gain, voltage stresses, continuous input and output current, and output polarity. To validate the performance of introduced converter, experimental results for a prototype with input voltage 24 V, output voltage 72 V for step‐up and 15 V for step‐down modes are given and results are examined. The maximum efficiency of the prototype is 93% and 89% for step‐up and step‐down modes, respectively. To evaluate the effect of proposed SPO for extracting maximum available power from PVs, simulation results of a grid connected PV system with two series connected SPOs is discussed.

LG = 50 nm T-gated and Fe-doped double quantum well GaN‒HEMT on SiC wafer with graded AlGaN barrier for future power electronics applications

High-performance LG = 50 nm graded double-channel (GDC)-HEMT featuring AlN top barrier, recessed T-gate and graded-AlGaN bottom barrier is designed and investigated. Two quantum wells are formed in the AlN-GaN-graded AlGaN-GaN multilayer structure developed on a SiC substrate and the clear double hump feature of the transconductance (GM), cut-off frequency (fT), and capacitance plots clearly illustrates the double-channel (DC) behavior. The investigations carried out to explore the impact of barrier thickness (both AlN & graded-AlGaN) revealed superior performance with the GM showing two peaks at 181.5 & 488.1 mS/mm, the peak-drive-current (ID_peak) with VGS biased at 3 V is 1.81 A/mm, maximum saturation drain current of 3.08 A/mm (VGS = 3V), and the fT derived from the left- and right-hump are 263.7 GHz & 354.2 GHz, respectively, when both barriers are 6 nm thin, attributable to enhanced 2DEG density due to the coordination of channels because of proximity and lower leakage. It has been noticed that when the bottom barrier is thick, the DC behaviour is less obvious due to insufficient gate access to the lower channel. We investigated the impact of varying the Al % in AlGaN top barrier on the DC/RF performance of GDC-HEMTs, demonstrating enhanced performance with increased Al content, particularly for Al0.35Ga0.65N. By using various metals, this study also investigates how gate engineering affects the electrical characteristics of the GDC-HEMT. The lower ϕm (work function) of the Al-gate led to better DC/RF performance. When the Schottky barrier rises as a result of the conduction band edge being elevated, the performance reduces, and the threshold voltage (Vth) increases. Since it is essential to comprehend the role that source resistance (Rs) & drain resistance (Rd) play in RF design, we have also conducted simulations by varying the source-gate gap (LGS) & drain-gate gap (LGD). Due to low Rs & Rd, it was determined that the GDC-HEMT performed better at the smallest LGS & LGD. The extraordinary performance strongly highlights the immense potential and applicability of the GDC-HEMTs for future broadband power amplifiers.

A hBN/Ga2O3 pn junction diode.

The development of next-generation materials such as hBN and Ga2O3 remains a topic of intense focus owing to their suitability for efficient deep ultraviolet (DUV) emission and power electronic applications. In this study, we combine p-type hBN and n-type Ga2O3, forming a pseudo-vertical pn hBN/Ga2O3 heterojunction device. Rectification ratios > 105 (300K) and [Formula: see text]400 (475K) are observed and are amongst the highest values reported to date for ultra-thin hBN-based pn junctions. The measured current under forward bias is ~2mA, which we attribute to the shallow Mg acceptor level (60 meV), and 0.2 µA at -10V. Critically, device performance remains stable and highly repeatable after a multitude of temperature ramps to 475K. Capacitance-voltage measurements indicate widening the depletion region under increasing reverse bias voltage and a built-in voltage of 2.34V is recorded. The hBN p-type characteristic is confirmed by Hall effect, a hole concentration of [Formula: see text] cm-3 and mobility of 24.8 cm2/Vs is achieved. Mg doped hBN resistance reduces by >108 compared to intrinsic material. Future work shall focus on the optical emission properties of this material system.

Hardware Testing Methodologies for Wide Bandgap High-Power Converters

Wide bandgap (WBG) power semiconductor devices are increasingly replacing silicon IGBTs in high-power and high-voltage power electronics applications. However, there is a significant gap in the literature regarding efficient testing methodologies for high-power and high-voltage converters under constrained laboratory resources. This paper addresses this gap by presenting comprehensive, hardware-focused testing methodologies for high-power and high-voltage WBG power semiconductor-based converter bring-up before the control validation phase steps in. The proposed methods enable thorough evaluation and validation of converter hardware, including device switching characteristics, driving circuit functionality, thermal management performance, insulation integrity, and sustained operation at full power. We utilized the double pulse test (DPT) to characterize switching performance in a two-level phase leg configuration, extract circuit parasitics, and validate magnetic components. The DPT was further applied to optimize gate driving circuits, validate overcurrent protection mechanisms, and measure device on-resistance. Additionally, a multicycle test was introduced to rapidly assess steady-state converter performance and estimate efficiency. Recognizing the critical role of thermal management in high-power converters, our methodologies extend to the experimental extraction of key thermal parameters—such as junction-to-ambient thermal resistance and thermal capacitance—via a heat loss injection method. A correlation method between temperature sensor measurements and junction temperature is presented to enhance the accuracy of device temperature monitoring during tests. To ensure reliability and safety, dielectric withstand tests and partial discharge measurements were conducted at both component and converter levels under conventional 60 Hz sinusoidal and high-frequency PWM waveforms. Finally, we highlight the importance of testing converters under full voltage, current, and thermal conditions through power circulating tests with minimal power consumption, applicable to both non-isolated and isolated high-power converters. Practical examples are provided to demonstrate the effectiveness and applicability of these hardware testing methodologies.

Unraveling High Temperature-Induced Glass Transition Effect on Underlying Multitimescales Dynamic Mechanisms of Epoxy Resin Insulation in Power Electronic Applications

Unraveling High Temperature-Induced Glass Transition Effect on Underlying Multitimescales Dynamic Mechanisms of Epoxy Resin Insulation in Power Electronic Applications

On the coupled effect of a MIS-based anode and AlGaN-polarized super-junction to reduce the local electric field for AlGaN/GaN Schottky barrier diodes

This work employs advanced physical models with the help of technology computer-aided design tools to systematically design and investigate AlGaN/GaN Schottky barrier diodes (SBDs), focusing on enhancing forward conduction and reverse blocking characteristics. A recessed metal/insulator/III-nitride (MIS) anode is demonstrated to manage electric field distribution. The incorporation of a 1 nm thick Al2O3 layer enables a reduced leakage current and a significant increase in breakdown voltage (BV). Subsequently, tailored field plates (FPs) further improve the BV of the MIS SBD to ∼1650 V but strong electric field magnitude will be found at the edge of the FP. Hence, a MIS SBD with a graded AlGaN barrier layer (MIS-GA SBD) is designed, featuring a gradient decrease in Al content along the [0001] direction. The generation of negative polarization charges within the barrier functions as a super-junction, significantly homogenizing the electric field. As a result, the MIS-GA SBD achieves a remarkable BV exceeding 3500 V, highlighting its strong potential for high-voltage power electronic applications.

Low turn-on voltage AlGaN/GaN Schottky barrier diode with a low work function anode and high work function field plate

AlGaN/GaN Schottky barrier diodes (SBDs) with a low work function W anode and a high work function Ni field plate on sapphire substrates are investigated in this Letter. The low work function metal W leads to the low turn-on voltage, while the high work function metal Ni maintains the leakage current and increases the breakdown voltage. An ultralow turn-on voltage of 0.23 V determined by the positive fixed charge at the AlGaN/Si3N4 interface is achieved in this W/Ni SBD. More importantly, benefitting from the dual-metal anode/field plate structure, the on-resistance decreases from 7.99 to 5.53 Ω mm, and the breakdown voltage increases from 493 to 1219 V. In addition, the turn-on voltage decreases less than 57%, and the on-resistance increases less than 186% at a high temperature up to 120 °C. The W/Ni SBD with a cathode–anode length of 18 μm and a field plate length of 4 μm shows a low turn-on voltage of 0.23 V, a low on-resistance of 5.53 Ω mm, a leakage current of 0.65 mA/mm, and a high breakdown voltage of 1.21 kV, indicating a great potential for power electronic applications.

Surgical Energy: A Unique Power Electronics Application in Healthcare

Surgical Energy: A Unique Power Electronics Application in Healthcare

Ultrahigh growth rate-induced thick 3C-SiC heteroepitaxial layers on 4H-SiC and its oxidation characteristics

The cubic 3C-SiC displays unique advantages in power electronics applications due to its high channel mobility and low SiO2/3C-SiC interface state density. Therefore, the epitaxial growth technology of 3C-SiC is one of the core technologies for preparing high-performance SiC power devices. In this work, we choose 4H-SiC as substrates to grow 3C-SiC with methyltrichlorosilane (MTS)-H2 complex precursor and acheieved an ultrahigh epitaxial growth rate up to 278 μm/h. Then the oxidation treatment has been conducted. The elemental composition, surface morphology, and crystalline phase of the prepared 3C-SiC/4H–SiC thick films were comprehensively characterized with SEM, Raman, XRD and TEM techniques. The growth mechanism and oxidation characteristics of the 3C-SiC/4H-SiC heteroepitaxial layers were analyzed based on experimental phenomena.

(Invited) Wide Bandgap Semiconductor Homo- and Hetero-P-N Junctions

Wide bandgap (WBG) semiconductors, such as gallium nitride (GaN), gallium oxide (Ga2O3), aluminum nitride (AlN), and diamond, hold immense promise for power electronics applications by drastically reducing power loss, enhancing switching frequency, and reducing system volume. However, effective doping (p-type or n-type) remains a substantial challenge for these materials, given that the p-n junction is a fundamental building block for device design. Selective-area doping, crucial for high-performance electronic devices and integrated circuits, poses another significant obstacle.We report recent progress on selective-area doping for GaN homo-p-n junctions. Although GaN shows substantial development in both p-type and n-type doping, achieving selective doping, especially p-type, remains challenging through techniques such as ion implantation, diffusion, or in-situ doping. Our investigation delves into the challenges of p-GaN regrowth using metal-organic chemical vapor deposition (MOCVD). Interface contaminants post etching and regrowth, such as silicon (Si), carbon (C), and oxygen (O), have been systematically investigated. An optimized interface treatment has been identified to effectively reduce surface charge and, consequently, reverse leakage current to the level comparable to the as-grown p-n junction. Additionally, a novel hydrogen plasma treatment has been proposed to realize selective doping for GaN, successfully applied to p-GaN gated high electron mobility transistors (HEMTs) to improve the dynamic performance by avoiding the etching damage and edge termination for vertical GaN p-n diodes to realize high breakdown voltage.β-Ga2O3 has emerged as a standout in power electronics applications, surpassing Si (3000×), SiC (10×), and GaN (4×) in Baliga’s figure of merit. Its great potential for mass production, facilitated by the availability of high-quality and large-size wafers, significantly enhances its attractiveness. However, challenges, including the absence of p-type doping due to deep acceptor states and a flat valence band, as well as exceptionally low thermal conductivity, limit its performance at high power and temperatures. Overcoming these challenges necessitates hetero-integration with semiconductors possessing p-type characteristics and high thermal conductivity. P-type diamond stands out due to its exceptional thermal conductivity, high critical breakdown field, and well-established p-type characteristics. Moreover, since the n-type doping of diamond also poses challenges, fusing the p-type diamond and n-type Ga2O3 to create a diamond/Ga2O3 p-n-heterojunction can effectively overcome doping bottlenecks for both materials. Our successful construction of a diamond/β-Ga2O3 hetero-p-n junction through the mechanical integration of bulk p-type diamond and bulk n-type Ga2O3 presents robust electrical performance up to 125 ℃, with hysteresis lower than 0.7 V @ 1 μA. Impressively, the ideality factor of the p-n junction is remarkably low at 1.28, and the rectification ratio exceeds 108. This approach has also been applied to other hetero-p-n junctions, such as the diamond/GaN structure, demonstrating consistent robust performance. These findings underscore the significant potential of the mechanical integration approach, offering a promising avenue to simplify the fabrication process and facilitate the widespread application of WBG heterojunctions.

(Electronics and Photonics Division Poster Award Winner) A High Breakdown Voltage Silicon Carbide (SiC)/Gallium Oxide (Ga2O3) Heterojunction Diode for High Power Applications

Wide and ultrawide bandgap semiconductors demonstrate exceptional performance due to their elevated energy bandgap. This characteristic results in breakdown electric fields surpassing those found in conventional silicon electronics by more than an order of magnitude. Furthermore, the high energy bandgap offers distinctive advantages, including enhanced efficiency, drift velocity, increased voltage blocking, and high-frequency switching, making these semiconductors crucial in pushing the boundaries of electronic technology. Gallium Oxide and Silicon Carbide, distinguished by their unique properties, contribute significantly to the advancement of power electronics. Gallium Oxide, with its wide bandgap of 4.6 – 4.9 eV and excellent thermal stability, stands out for its ability to handle high electric fields and temperatures. Silicon Carbide, on the other hand, boasts a robust combination of high thermal conductivity and a wide bandgap of 3.26 eV, making it well-suited for high-power and high-temperature applications. The combination of these two materials in a heterojunction holds promise for the development of high-performance power devices. In this study, we propose a novel high breakdown voltage Silicon Carbide (SiC)/ Gallium Oxide(Ga2O3) heterojunction diode through TCAD Sentaurus. We present a comparative study of the breakdown voltage and electric field across different heterojunction lengths and under various doping concentrations. The investigated heterojunction showcases a high breakdown voltage of 1899V, making it a promising candidate for advanced power electronics applications. Furthermore, simulation results revealed a significant increase in the breakdown voltage of the SiC/Ga2O3 heterojunction, escalating from 1899 V to 4864 V when extending the heterojunction length. Improved specific ON resistance (RON, sp) and Baliga figure-of-merit (BFOM) will also be presented.

Active elimination of DC bias current of a SiC based dual active bridge by controlling the dead time period

AbstractDual active bridge (DAB) is an isolated DC‐DC converter gaining wider attention in power electronics applications. The high frequency (HF) transformer is an integral part of the DAB which is prone to saturation. Silicon carbide (SiC) based DAB are generally preferred for highly efficient power conversions, calling for an extremely low DC resistance of the transformer. This aggravates the DC bias issue significantly. The DC bias current generally flows due to the mismatch in static and transient switching of active devices, leading to eventual saturation of the transformer. This paper proposes an active method to precisely control the dead time of the devices (8–100 ns) without sacrificing the voltage utilization of the converter. This method does not require a sophisticated DC offset current measurement technique. The field programmable gate array (FPGA) based control platform on the gate driver side executes the proposed algorithm. The proposed control is experimentally verified in a 5 kW SiC based converter. The control implementation methodology is discussed with the support of necessary experimental results.