United States

The first GaN power devices has been commercialized over a decade ago. These devices have been demonstrated in multiple end applications including chargers for cell phones, motor drives, DC/DC converters for servers or class-D audio amplifiers. GaN devices delivers clear benefits in system performance or cost in those end applications, but true commercial success has been mostly limited to chargers for cell phone or other portable devices. This limited commercial success so far is at least partly due to a restricted supply of GaN device production at a competitive cost point. The various fabless startups are facing the issue of high GaN wafer price at foundries (6-inch today) and limited value adder of discrete device design. More functionality integration on GaN die aims to increase their value adder of these products vs. discrete devices with mixed results and market adoption success. This presentation will argue that true integrated device manufacturer with high volume 8-inch internal manufacturing, fully focused on GaN is the game changer required to bring GaN power devices out of peripheral applications and into mainstream high-volume end-products, including mobile phones. In such ecosystem, roadmap based on discrete devices from 650V down to 30V and system-in-package integration is highly attractive for foreseeable future. This talk will give examples of latest device innovation including 40V bi-directional GaN switch reducing on-state resistance by 50%, chip size by 70% and temperature rise by 40%. First ever GaN product designed directly into mobile phone handset.

IEEE WiPDA 2022

GaN device innovation matched with manufacturing capacity and quality propels GaN to new markets

shoot-through detection

on-state resistance

ultrafast sensor

prognostics

diagnostics

Download the proceedings [here](https://underline.io/events/372/lounge)
 
 
 The IEEE Workshop on Wide Bandgap Power Devices & Applications (WiPDA) provides a forum for device scientists, circuit designers, & application engineers from the Power Electronics & Electron Devices Societies to share technology updates, research findings, experience & potential applications.
 
 **Topics of interest**
* Heteroepitaxial & Bulk Materials Growth
* Gate Dielectrics & Surface Passivation
* Device Structures & Fabrication Techniques
* Device Characterization & Modeling
* Very-High Efficiency Or Compact Converters
* Safe Operating Areas Of Wide Bandgap Devices, including Short Circuit, Spike, &Transient Tolerance
* Harsh Environment (High Temperature) Operation & Reliability
* Packaging Power Modules & ICs
* Gate Drive & Other Auxiliary Circuits
* High-Performance Passive Components
* Hard-Switched & Soft-Switched Application Analysis
* Applications in Renewable Energy & Energy Storage, Transportation, Industrial Drives, Grid Power Systems, Space and Aerospace
* Wide Bandgap System Design Philosophies & Strategies
* Radio Frequency (RF) GaN
* Technology Roadmap of Wide Bandgap Including Devices, Applications and Packaging

You must register to attend this event. If you haven't done so already, please use the link below to register for the event. All registered attendees will have access to the event site on November 4th.

Registration Is Required

The IEEE Workshop on Wide Bandgap Power Devices & Applications (WiPDA) provides a forum for device scientists, circuit designers, & application engineers from the Power Electronics & Electron Devices Societies to share technology updates, research findings, experience & potential applications.

keynote

GaN Growth Beyond Consumer Applications: What is the Right Level of Integration?

Wide-bandgap Device and related technology to Enable Medium Voltage Distribution Power Grid

DC short circuit fault ride-through is a critical feature for the reliability and performance of DC microgrids. This paper presents the advantage that SiC-based devices offer for designing a Dual-Active Bridge (DAB) DC-DC converter while considering DC short circuit events. It is known that SiC-MOSFET devices have a higher transient current carrying capability than Si-IGBT devices due to their superior thermal conductivity. This characteristic of SiC-MOSFET devices is utilized to improve the design of DAB for DC short circuit fault ride-through applications. An analytical model is developed to understand the performance of a DAB during DC short circuit faults. Switching and thermal simulations are used to validate the analytical model and compare DAB designs based on SiCMOSFET and Si-IGBT. The advantages of SiC-MOSFET enabled DAB compared to Si-IGBT enabled DAB are also quantified for a particular application of DAB in a DC microgrid. It is shown that for fault ride-through applications, DAB enabled with SiCMOSFET can be designed for lower phase shifts compared to Si-IGBT enabled DAB, which inherently reduces the inductor size and circulating current in a DAB.

Advantages of SiC-Based Devices on the Design of Dual-Active Bridge DC/DC Converter for DC Faults

In this paper, the gate driving characteristics of a SiC cascoded Junction Field Effect Transistor (JFET) is explored. Firstly, a Conventional Gate Drive (CGD) circuit is analyzed and implemented, followed by the proposal and implementation of two Active Gate Driving (AGD) methods for the cascoded JFET. Two approaches of gate control are explored: i) using the low-voltage -MOSFET gate & (ii) using the JFET gate. Switching characteristics during turn-on and turn-off for the CGD and both AGD approaches are compared, and it is observed that the proposed AGD circuits provide controllability of both switching edges and thus allowing an application optimized switching operation. Analytical, simulation and experimental results are shown to verify the proposed methods.

Active Gate Driving of Cascoded SiC JFETs

Resonant converters are used extensively for voltage regulation and isolation purposes in electric vehicles. The power level and frequency of the converters is increasing with the ongoing development of the wide-band-gap devices, which brings more challenges to the design of magnetic components. The first challenge is that such high power and frequency make it hard to make proper Litz wire. In this paper, a new current sharing method for paralleled Litz wire transformers is introduced. Using this method, the transformer can stand much higher current without increasing the cost or volume. And the power level can be further increased by integrating more matrix transformers. The second challenge is the resonant inductance integration. Different resonant inductance integration methods are summarized and compared. And controlling the leakage inductance by properly breaking the interleaving structure is proposed in this paper. Using this method, the desired leakage inductance can be reached without sacrificing too much winding loss. Comprehensive transformer design and optimization procedure is also presented in this paper. A 30 kW 100 kHz Serial Half Bridge DC-DC converter prototype is designed to verify the methods at last.

High Frequency High Power Integrated Transformer Design for Resonant Converters with SiC Devices

New semiconductor devices based on wide bandgap materials are emerging in medium voltage power electronic converter applications, presenting new opportunities to the industry relying on semiconductor devices. SiC MOSFETs with blocking voltages of 10 kV (and above) is a promising technology, however, their fast switching transitions result in increased output voltage slew rate (dv/dt), which poses challenges to the applicability of the SiC MOSFET technology. This paper examines the impact of the increased dv/dt on the applicability of an off-the-shelf closed loop hall-effect current sensor when utilized in a medium voltage SiC MOSFET based power electronics converter. Analysis of the capacitive couplings in the current sensor is presented along with an experimental determination of the parasitic capacitance between its primary conductor and secondary winding. Experimental measurements have identified two distinct noise components in the current sensor measurement path due to: 1) capacitive coupling between the primary conductor and secondary winding, and 2) an inferred capacitive coupling into the active circuitry of the current sensor

Noise Analysis of Current Sensor for Medium Voltage Power Converter Enabled by Silicon-Carbide MOSFETs

A 99% efficient power converter is applied to an electrocaloric heat pump prototype for the first time, enabling cyclic electrical field variation in electrocaloric capacitors and high heat pump performance. The electrocaloric effect is an almost fully reversible temperature change in special dielectrics caused by changed electrical field. The GaN power converter achieves high efficiency by zero-voltage switching hysteretic current control. Blocks of commercial multi-layer ceramic capacitors which exhibit an electrocaloric effect are efficiently charged and discharged, synchronized to contacting to a heat sink and source by actuators, which forms a heat pump prototype. Brayton cycles are caused by trapezoidal voltage. Then, arbitrary voltage (E-field) variation for Carnot-like cycles with quasi-isothermal heat transfer is demonstrated and verified by the measured almost constant heat flux during contact to the heat sink. The performance of electrocaloric heat pump prototypes in literature was limited by losses of LC resonant circuits, and is improved by an up to 15.5-fold decrease by this work. The work demonstrates electrocalorics as an emerging power electronics application and contributes to realize future efficient and emission-free, solid state, and electrocaloric heat pump systems.

GaN Power Converter Applied to Electrocaloric Heat Pump Prototype and Carnot Cycle

This paper demonstrates a GaN-based three-level inverter design for an electric vehicle (EV) traction application. The basic power block is a three-level active neutral point clamped (3L-ANPC) converter operating at 800 V DC bus voltage with the use of two paralleled 650 V, 60 A GaN E-HEMTs. The paper focuses on switching mode selection for better thermal performance of high-power 3L-ANPC inverters. The paper presents design details and guidelines for power layout structure and gate driver. The key parasitic inductances of the designed power block are extracted using ANSYS Q3D. A PLECS simulation model using the device loss parameters shows approximate power delivering capability of 41 kW for the designed forced air-cooled three-phase inverter. Experimental double pulse test results are presented with low voltage overshoot to verify the low inductance power loop design. Experimental results of the three-phase 3LANPC inverter operation at 70 kHz switching frequency are presented for delivered output power of 5.1 kW at 550 V DC.

Design Considerations of a GaN-Based Three-Level Traction Inverter for Electric Vehicles

In this paper, a novel structure of three-port with zero voltage switching (ZVS) dc-dc converter is proposed. Three-port dc-dc converters are widely applicable in hybrid energy generating systems to provide substantial power to sensitive loads. One of the ports of the proposed converter is interfaced with a storage such as a battery which makes the converter capable of supplying the load even if the main renewable energy supply of the proposed converter (e.g. photovoltaic cells) is not able to generate power. The proposed converter operates in two operations of charging the battery port and the mode when the battery discharges to the load. In addition, it has ZVS operation for all utilized switches and can eliminate the input current ripple. The ZVS of the switches is provided by the leakage inductances of the used coupled inductors. Also, the voltage control of each of the terminals is achieved by three active switches. In this paper, the proposed topology is analyzed theoretically for all operating modes, also, the voltage and current equations of all components are calculated. Furthermore, the required soft switching and zero input currents ripple conditions are analyzed. Finally, the accuracy performance of the proposed converter and the analytical results is verified by the PSCAD/EMTDC simulation and experimental results for 1MHz switching frequency operation. Applying high frequency and using GaN Fets leads to achieve a more compact prototype of the proposed topology.

Novel High-Voltage-Gain High-Frequency Non-Isolated Three-Port DC-DC Converter with Zero Input Current Ripple and Soft Switching Capability

In this work an approach for a direct experimental comparison of the application-oriented performance between two high current GaN DC/DC converters based on 7 mΩ, 100 V GaN HEMTs in a commercial off-the-shelf top-cooled package and 5 mΩ, 100 V GaN HEMTs embedded in a thermally-optimized single-chip package is given. The two packaging versions are compared by a maximally identical implementation of the power and gate loops in a 48 V, 300 kHz buck converter with two parallel GaN HEMTs. In the single-chip package the die is directly mounted on a 12×6 mm2 copper-heat spreader offering a significantly lower thermal resistance to heatsink (1.69 K W−1) in comparison to the commercial off-the-shelf version (2.45 K W−1). For a direct benchmark, the COTS-based converter has an identical power-loop to the SCP-version with a novel gate-drive concept. Both versions have an efficiency of 96.8 % at 65 A output current (output power: 1.5 kW), while the commercial off-theshelf version has a better efficiency for lower currents, due to its better hard-switching Figure-of-Merits and therefore lower switching losses and reaches an output current of up to 80 A (output power: 1.75 kW). A detailed analytical loss breakdown for the different transistors in dependence of the temperature and output current is given to proof the measured current point, where the efficiencies of both converters are identical, since the higher switching losses of the SCP version are compensated by lower conduction losses at higher currents and temperatures compared to the smaller COTS transistor. Finally, an outlook on further improvements for reaching higher output currents and potential converters for a more fair comparison of different thermally optimized SMD packages are given.

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GaN Growth Beyond Consumer Applications: What is the Right Level of Integration?

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