Simulation and performance comparison of Si and SiC-based interleaved boost converter

With the advancement in technology, the need for high efficient, switching speed and compact size of converters are gaining popularity. These converters require power devices having high breakdown voltage, thermal conductivity, switching frequency and operating temperature. Silicon devices exhibit limitations in switching frequency and operation at high temperature. The limitations of Si devices lead to advancements of wide band gap devices. The superior electrical properties of WBG devices make them potential candidates for use in high temperature, voltage and switching speed converter applications. Among the many WBG devices, silicon carbide, diamond and gallium nitride are a promising candidates. This paper deals with comparisons between conventional Si and GaN devices and highlights overall state of the art and future trends of GaN devices.

Wide-bandgap power semiconductor devices offer enormous energy efficiency gains in a wide range of potential applications. As silicon-based semiconductors are fast approaching their performance limits for high power requirements, wide-bandgap semiconductors such as gallium nitride (GaN) and silicon carbide (SiC) with their superior electrical properties are likely candidates to replace silicon in the near future. Along with higher blocking voltages wide-bandgap semiconductors offer breakthrough relative circuit performance enabling low losses, high switching frequencies, and high temperature operation. ARPA-E’s SWITCHES program, started in 2014, set out to catalyze the development of vertical GaN devices using innovations in materials and device architectures to achieve three key aggressive targets: 1200V breakdown voltage (BV), 100A single-die diode and transistor current, and a packaged device cost of no more than ȼ10/A. The program is drawing to a close by the end of 2017 and while no individual project has yet to achieve all the targets of the program, they have made tremendous advances and technical breakthroughs in vertical device architecture and materials development. GaN crystals have been grown by the ammonothermal technique and 2-inch GaN wafers have been fabricated from them. Near theoretical, high-voltage (1700-4000V) and high current (up to 400A pulsed) vertical GaN diodes have been demonstrated along with innovative vertical GaN transistor structures capable of high voltage (800-1500V) and low RON (0.36-2.6 mΩ-cm2). The challenge of selective area doping, needed in order to move to higher voltage transistor devices has been identified. Furthermore, a roadmap has been developed that will allow high voltage/current vertical GaN devices to reach ȼ5/A to ȼ7/A, realizing functional cost parity with high voltage silicon power transistors.

A cascaded bridgeless totem-pole multilevel converter and its model predictive control (MPC) are proposed for the power interface of 400 V dc-powered data centers. Wide bandgap devices such as gallium nitride (GaN) or silicon carbide (SiC) MOSFETs with very low reverse recovery charge are utilized in the proposed totem-pole converter to reduce the switching loss. DC bus voltage error can be effectively mitigated by adopting the proposed MPC strategy when compared with a conventional proportional-integral (PI) control; the proposed MPC also exhibits smaller overshoot and much faster response when the load changes, and can operate at lower switching frequencies, thus further reducing switching losses. Furthermore, it is easier to balance the dc-bus voltages in each module using the proposed MPC control. The simulation and hardware-in-loop test results of conventional PI and proposed MPC controllers are presented to validate the effectiveness of the proposed converter and its control algorithm.

MOSFETs built using wide band gap (WBG) materials offer numerous benefits to power electronic circuits. These benefits are quite apparent in applications requiring breakdown voltages ≥ 600V, where Silicon IGBTs are typically used due to their combination of high breakdown voltage and low conduction losses. Compared to Silicon IGBTs, WBG MOSFETs offer very short turn-ON and turn-OFF times, which reduce switching losses and enable significantly higher switching frequencies. This paper explores the application of WBG MOSFETs to motor drives, where higher switching frequencies reduce motor losses and torque ripple and allow higher control bandwidth, thus enabling greater output frequencies needed to operate motors at higher speeds. Specifically, two-level voltage source inverters utilizing Silicon Carbide (SiC) MOSFETs are constructed to operate a 1 HP induction motor. Experimental results are presented which show that the short turn-ON and turn-OFF transients as well as high switching frequencies lead to increased shaft voltage and conducted ground currents. Mitigation techniques are implemented and evaluated, including clamp-on ferrites and an open-end winding drive implementation. The shaft voltage and ground currents are found to be best suppressed in an open-end winding drive utilizing clamp-on ferrites.

Nowadays, Uses for transportation are evolving in the direction of getting more electrified due to rising fuel costs and environmentally hazardous pollutants due to which The grid’s need for power is increasing dramatically. As the only solution for this is to diminish the power consumption of Electric Vehicles (EV). Enhanced component efficiency can lead to improved electric vehicle performance. Wide band gap (WBG) semiconductors, in particular silicon carbide (SiC) and Gallium Nitride (GaN), are ideal candidates of choice to address the recent growing demand in both high efficiency and great power density converters about electric vehicles. Due to their the capacity to switch at a high frequency, high temperature, high voltage, reduced size and reduced conduction losses makes them superior than Si semi-conductors. WBG devices have some properties which include rapid electron mobility, high breakdown field, and big band gap low on-state resistance and capacitance, lower co-efficient of thermal expansion (CTE) and high stability. This paper includes a study on WBG devices, their properties, and the increased efficiency of power converters i.e DC-DC boost converter and single-phase full bridge inverter using LTSpice simulation tool.

The development of wide bandgap (WBG) devices in recent years, such as silicon carbide (SiC) and gallium nitride (GaN) power devices, has resulted in power converters with power densities and efficiencies that are not possible with traditional silicon (Si) devices. While the fast switching speed of WBG devices enables higher converter efficiency and power density, a number of issues are created such as increased sensitivity to parasitics, EMI noise, high voltage and current overshoot and ringing, and heat centralization in semiconductor devices. Resonant and soft-switching techniques can be effective in resolving these issues and allow even higher power densities and efficiencies to be achieved.

The nature of reverse recovery losses is examined in hard-switched and soft-switched converters, using silicon (Si), silicon carbide (SiC), or gallium nitride (GaN) devices. A loss model and experimental results with a prototype 150-to-400 V, 150 W, boost converter operated at switching frequencies between 500 kHz and 2 MHz are used to characterize and quantify losses related to diode reverse recovery. It is found that reverse-recovery related losses with Si diodes cannot be neglected even when the converter is soft switched, with zero-current switching of the diode and zero-voltage switching of the transistor. The switching losses with SiC or GaN diodes are substantially smaller in all cases considered, and can be reduced to negligible values when the converter is soft switching.

Gallium Nitride (GaN) and Silicon Carbide (SiC) power devices are segmented in the Wide Bandgap (WBG) device market: GaN devices are suitable for high-frequency but low-voltage applications; SiC devices are suitable for low-frequency but high-voltage applications. Cascoding a GaN HEMT and a SiC JFET best utilizes the advantages of both of these WBG power devices. Like GaN devices, the cascode GaN/SiC device is easy to drive at high frequencies and has low gate loss; like SiC devices, it also has relatively high voltage rating and low C oss energy loss at high frequencies. In previous studies, power circuits using the cascode device achieved higher power density than circuits using only a SiC device but efficiency similar to that of a SiC device [1]. In this paper, we present our investigation of the gate loss mechanism of the SiC JFET in the cascode structure and our finding that the loss can be greatly reduced by minimizing the gate resistance of the SiC JFET (R g,Jfet ). Simulation results showed that reducing R g,Jfet from 6 Ω to 1 Ω at 13.56 MHz leads to a 5× loss reduction, and experimental data verified the simulation trend. Here we provide a simple guideline to optimize the cascode GaN/SiC device and achieve better performance in high-frequency and high-voltage applications.

Fast and high-frequency switching operation of wide-bandgap power semiconductor devices such as Silicon carbide (SiC) and Gallium nitride (GaN) could cause severe electromagnetic interference (EMI) noise problem in high and wide frequency range. This report experimentally investigates the dependency of gate drive circuit configuration on EMI noise characteristics of SiC-based half-bridge converter.

Gallium Nitride (GaN) and Silicon Carbide (SiC) power cascode devices both take advantage of a low-voltage enhancementmode Silicon power MOSFET coupled with a high-voltage depletion-mode GaN HEMT or SiC JFET to realize high switching frequencies with the intention of avoiding charge trapping and threshold voltage drift in the gate oxide traps of enhancementmode SiC MOSFETs. Nevertheless, in this paper it is shown that SiC and GaN Cascodes will also suffer from the gate threshold voltage drift when subjected to significant electrothermal stress. This is partly due to the natural drift of threshold voltage in the gate, and partly due to the impact of the leakage current by the high-voltage device. The threshold voltage drift can lead to permanent degradations and potential failures, and as such is the subject of this investigation.

Increasing the power density of PV inverters have been of great interest in the PV industry. With a smaller and lighter inverter, the installation cost can be greatly reduced, making solar energy more affordable. To improve the power density of PV inverters, a new internal parallel converter has been proposed in the literature and prototyped. This paper presents the key design considerations of the Gallium Nitride (GaN) based power stage as the high switching frequency (HSF) module in the modularized prototype. Two issues have been addressed in detail, i.e. the sizing of film capacitor based flying capacitor (FC) and design of GaN power board. A current stress based sizing has been investigated for FC indicating that the volume of the FC bank is dominated by the current stress instead of the switching frequency. Furthermore, design of the GaN power board based on insulated metal substrate (IMS) board has been discussed in detail. In addition to improved thermal performance, the metal substrate can serve as a shielding layer and help reducing the power loop parasitic inductance. Experimental results have confirmed that the designed GaN HSF module can safely operate under full power.

This paper describes a comprehensive analysis of a three-phase two-level silicon carbide (SiC) MOSFET V2G inverter including the LCL filter design. The efficiency is compared between the SiC MOSFET and Si IGBT. Using a SiC device enables the inverter to operate at high switching frequency and this leads to improved efficiency up to 99.05% at 10 kHz and 97.71% at 100 kHz switching frequency. The output LCL filter is also designed based on a specific switching frequency and the filter value is most significantly reduced at the highest switching frequency. The SiC inverter and LCL filter is simulated using LTSpice and MATLAB Simulink.

The advent of wide bandgap (WBG) semiconductors, such as silicon carbide (SiC) and gallium nitride (GaN), has enabled power electronics with increasing current densities and switching frequencies. A byproduct of these improved electrical characteristics is an increase in thermal power density. Indeed, the full capability of WBG semiconductors may be underutilized if the thermal management solution cannot keep pace with the device heat generation density. Further, as many power electronics devices are integrated into a power module form factor containing a metal baseplate to allow heat spreading from high heat fluxes generated at semiconductor dies, system integrators are often sensitive to cost and weight considerations in building up systems with traditional power module designs. In this paper, a polymer baseplate with integrated microconvective cooling (PBIMC) is designed and built as a low-weight, cost-effective alternative for metal baseplates on power module devices. Microconvective cooling, featuring optimized single-phase impingement cooling and effluent fluid flow control, provides high power density heat removal from localized heat flux areas in power module packages to obviate the need for a metal heat spreader. Thermal performance of the PBIMC is tested on a thermal test vehicle representative of an IGBT power module to power densities up to 200W/cm2 and compared to an off the shelf minichannel cold plate. The PBIMC achieved equivalent per IGBT case-to-fluid areal thermal resistances of 0.15 K-cm2/W, a 69% decrease compared to the baseline cold plate. Additionally, thermal crosstalk was shown to be reduced by up to 89% when moving from the cold plate to the PBIMC, demonstrating potential advantages in utilizing thermal management techniques that do not feature heat spreading. The prototype-level polymer baseplates showed a > 80% decrease in weight compared to a traditional power module metal baseplate. The study concludes that the PBIMC shows promise as a solution for high current density power electronics in weight sensitive applications, while providing opportunities for cost savings.

In this paper, an efficiency comparison of neutral-point-clamped (NPC) inverters and bipolar switch NPC (T-Type) inverters is studied and the result shows that the T-Type inverter is more efficient at lower switching frequencies. Nevertheless, its efficiency suffers when the switching frequency increases due to high switching loss of the equipped high voltage power switches. In order to reduce switching loss and hereby enhance efficiency, a newly proposed circuit-level decoupling modulation (CLDM) scheme is applied for these two widely used three-phase three-level inverters, as well as their corresponding loss analyses are addressed. The switching loss reduction is evaluated comprehensively under variant modulation indices and load power factors. The analysis results reveal that the CLDM is an alternative discontinuous pulse-width modulation (DPWM) approach for inverters with high switching frequencies in order to achieve superior output voltage quality without lowering efficiency.

Pulse power converters demands single high voltage and current pulse shape waveform in high temperature, heavy neutrons, and ions radiation environment, where ${\text{50}}\% \sim {\text{75}}\%$ voltage derating margin is typically required for the power devices. silicon carbide (SiC) mosfet s are promising to improve radiation reliability owing to wide band-gap. However, the conventional converters with off-the-shelf commercial SiC mosfet s cannot provide enough voltage margin accordingly. A stack-capacitor pulse converter topology is proposed to reduce the voltage stress of switching devices and capacitors and improve the voltage derating capability significantly. The main idea is to build high voltage with multiple low voltage stacks instead of single high voltage capacitors, so that SiC mosfet s can be applied with improved voltage margin. The method is to charge the stack-capacitors in parallel with fast charging speed, and discharge in series for high pulse voltage. The converter operates at higher switching frequency, which reduces the weight and size of the magnetic components. A 300-kHz prototype with 18–28 V input and 1 kV/ 100 A output was built using 650 V SiC devices, demonstrating 75% reduction of the voltage stress of the capacitors and power devices compared with the conventional converters.