The trend in power electronic applications is to reach higher power density and higher efficiency. Currently, the wide band-gap devices such as silicon carbide MOSFET (SiC MOSFET) are of great interest because they can work at higher switching frequency with low losses. The increase of the switching speed in power devices leads to high power density systems. However, this can generate problems such as overshoots, oscillations, additional losses, and electromagnetic interference (EMI). In this paper, a novel active gate driver (AGD) for improving the SiC MOSFET switching trajectory with high performance is presented. The AGD is an open-loop control system and its principle is based on gate energy decrease with a gate resistance increment during the Miller plateau effect on gate–source voltage. The proposed AGD has been designed and validated through experimental tests for high-frequency operation. Moreover, an EMI discussion and a performance analysis were realized for the AGD. The results show that the AGD can reduce the overshoots, oscillations, and losses without compromising the EMI. In addition, the AGD can control the turn-on and turn-off transitions separately, and it is suitable for working with asymmetrical supplies required by SiC MOSFETs.

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A Novel Active Gate Driver for Improving SiC MOSFET Switching Trajectory

Silicon carbide (SiC) power transistors have started gaining significant importance in various application areas of power electronics. During the last decade, SiC power transistors were counted not only as a potential, but also more importantly as an alternative to silicon counterparts in applications where high efficiency, high switching frequencies, and operation at elevated temperatures are targeted. Various SiC device designs have been proposed and excessive investigations in terms of simulation and experimental studies have shown their advantageous performance compared to silicon technology. On a system-level, however, the design of gate and base drivers for SiC power transistors is very challenging. In particular, a sophisticated driver design is not only associated with properly switching the transistor and decreasing the switching power losses, but also it must incorporate protection features, as well as comply with the electromagnetic compatibility. This paper shows an overview of the gate and base drivers for SiC power transistors which have been proposed by several highly qualified scientists. In particular, the basic operating principle of each driver along with their applicability and drawbacks are presented. For this overview, the three most successful SiC power transistors are considered: junction-field-effect transistors, bipolar-junction transistors, and metal-oxide-semiconductor field-effect transistors. Last but not least, future challenges on gate and base drivers design are also presented.

Gate and Base Drivers for Silicon Carbide Power Transistors: An Overview

Efficiency is a key design parameter when designing the power converters for domestic induction heating applications, since it determines not only the environmental impact of the power converter but also its final performance and reliability. In this paper, the design of high-efficiency converters for induction heating applications is discussed, focusing on the advantages of using wide bandgap devices. As a conclusion, a multiple-output boost resonant ac-ac converter is proposed, significantly improving current state-of-the-art efficiency and achieving a reduced component-count solution for multiple-load systems. The proposed converter has been tested through a dual-output boost resonant inverter for domestic induction heating applications. The design procedure is detailed, including the design of an optimized gate drive circuit for this application. Experimental results show significant improvements in efficiency in the whole operating range, and an accurate output power control, proving the benefits and feasibility of the proposed SiC-based converter.

Design and Implementation of a High-Efficiency Multiple-Output Resonant Converter for Induction Heating Applications Featuring Wide Bandgap Devices

Galvanic isolation is becoming an essential requisite for several low-power applications, such as sensor interfaces and medical devices. In the last years, different solutions of silicon-integrated data transmission with galvanic isolation have been proposed that are based on RF links [1], capacitive couplings [2] or integrated coreless transformers [3]. As far as the power transfer is concerned, a dedicated link exploiting a discrete transformer is the typical solution. State-of-the-art devices currently adopt post-processed technologies and thick Au metals to implement the power link [4]. In this work, a fully integrated system is demonstrated for galvanically isolated power and bidirectional half-duplex data transfer by using a single integrated transformer [5].

16.7 A fully-integrated half-duplex data/power transfer system with up to 40Mb/s data rate, 23mW output power and on-chip 5kV galvanic isolation

This work presents a driver and controller integrated circuit (IC) for depletion-mode gallium nitride (GaN) high-electron-mobility transistors (HEMTs). The dual-mode driver can be configured for cascode-drive (CD) or HEMT-drive (HD) mode. In the CD mode, a cascode low-voltage DMOS is driven to achieve high-speed normally OFF operation. An active clamping circuit is proposed for the DMOS breakdown protection. In the HD mode, an HEMT gate driver with negative drive-voltage capability and programmable slope control is presented. A digital peak current-mode controller is also integrated with the dual-mode driver. The IC was implemented in a 140-nm automotive bipolar-CMOS-DMOS silicon-on-insulator process. The driver/controller IC is copackaged with an optimized 600-V GaN HEMT fabricated in a GaN-on-Si process. The solution was verified to operate at up to 1 MHz in a 35-W boost converter prototype and achieves a programmable switching-node $dv/dt$ of up to 20 V/ns. To the best of the author's knowledge, this is the first monolithic integration of a cascode MOSFET, device driver, and digital current-mode controller that is designed specifically for high-voltage GaN devices.

A Dual-Mode Driver IC With Monolithic Negative Drive-Voltage Capability and Digital Current-Mode Controller for Depletion-Mode GaN HEMT

This paper presents the single channel galvanically isolated gate driver optimized for driving a normally-on silicon carbide junction field effect transistor (SiC JFET) also presented at ISSCC 2012 [1]. The idea of the chosen direct drive JFET concept is to switch power with a normally-on SiC JFET, using the high voltage breakdown capability of the SiC JFET and ensuring a safe normally-off behavior using a normally-off low voltage MOSFET in series. By controlling the transistor gates individually the JFET can be driven with minimum switching losses and good control. The driver makes the operation and handling of normally-on SiC JFETs as safe as normally-off switches, thereby simplifying the integration of normally-on SiC JFETs into systems like switch mode power supplies. To transfer the signal from the controller to the driver over a needed galvanic isolation of 1700 V a two chip solution with a coreless transformer arranged in one package was chosen, using a 0.6 μm BiCMOS and a 0.8 μm BCD technology. Powering of the gate driver through bootstrapping has been made possible, due to the direct drive JFET concept and the further integration of supervision and control circuitry and a negative voltage regulator that regulates the entire p-substrate of the driver chip. Tested together with the JFET in a buck converter efficiencies over 99% have been measured.

C. Lindholm

Papers

An Optimized Driver for SiC JFET-Based Switches Enabling Converter Operation With More Than 99% Efficiency