2021
We propose a results of a simple motor inverter simulation with WLTC droving mode using PLECS. PLECS is the simulation platform of power electric systems.
We propose a SiC MOSFET model for circuit simulation. We validated the accuracy of the proposed model by measured switching waveforms of an inductive load switching evaluation circuit. Simulation speed of the model has been validated by a three-phase inverter simulation. Excellent results have been observed for both accuracy and speed.
2020
Developping a method to track GaN transistor degradation over time with recurrent neural networks. From measurements easily obtained during the normal operation of the transistor we can detect if the behavior is standard or if there is an anomaly. This method should enable live monitoring of device health.
We employed a single resonant tunneling diode as both a transmitter and a receiver simultaneously, and demonstrated its impact in terahertz imaging applications.It leads to simplify terahertz imaging systems.
Influence of device parameter variation on current sharing between SiC MOSFETs connected in parallel has been studied. From the simulation results, we reveal the device parameters which mainly affetct the static and dynamic current sharing behavior of the devices. We also evaluate the effect of the current sharing mismatch on energy loss for each device.
The presentation reveals the pore size and shape dependences on sintered silver mechanical durabilities.
From stress-strain results, uniform crystal structure make sphere and small pore shape. In terms of thermal cycle reliability using sintered silver materials, uniform structure with small and sphere pore state is essential.
A method to diagnose whether the accelerometer itself is in a state of mechanical deterioration by statistically examining the output data from the accelerometer while the machine health monitoring application system is in continuous operation.
The Id-Vd charactaristic in high-Id and high-Vd range of SiC-MOSFET shows incremental trend instead of saturated Id behavior. By TCAD simulation, the self-heating at measurement reproduce well this incremental trend.
In the evaluation of the impurity level depth in Zn-doped GaN, it was found that Zn behaves as an acceptor impurity in GaN by forming the state at 0.3 eV from the top of the valence band. Normaly-off operation was confirmed in an AlGaN/GaN HFET with a 0.1 μm mesa shape using Zn-doped GaN as the gate layer.
To maximise the switching capability of SiC-MOSFET, we introduce a current and voltage hybrid source gate driver and design method.
The adoption of small Qoss and small Qg GaN transistors was found to be a useful option to solve both the miniaturization and high power conversion efficiency of switching power supplies. Isolated 48 V-12 V LLC converter with a switching frequency of 2 MHz and 100 W class was fabricated, and the maximum power conversion efficiency reached 95.3%.
The basic characteristics of the latest generation of ROHM's SiC-MOSFETs are presented and compared with the current generation of devices in production. On the other hand, it is often assumed that better power device characteristics improve power-circuit performace, but it is not that simple. For better system-level performance, our researches of power applications and the related simulations are also presented.
This research investigates how the mechanical properties of sintered silver (s-Ag) as a die attach material influence its heat-cycle reliability. s-Ag mechanical fatigue life was 500 times under elastic stress. To investigate the correlation between fatigue mechanical test and thermal shocked test (TST), we performed TST with different temperature patterns. From TST results, higher TST gives faster degradation of s-Ag.
Twisted bilyaer graphene can be mocified the energy band structure by changing the rotation angle. Especially, the 1.1degree called as a magic angle can be shown the superconductivity. However, the next challenge is to obtain big scale (millimeter-scale) TBG samples. This research was shown to obtain it with using transfer graphene after annealing.
The method to control graphene angle on C face in SiC(000-1) is not performed, so this research is challenging to control it.
We have devloped the world's first small general-purpose PLCC package and a high-gain antenna integrated package for terahertz devices. There are promising as a high-frequency package form that are functional and can be mass produced.
This paper presents a semi-theoretical method for predicting the turn-off surge voltage (Vsurge) in double-pulse test (DPT) using a power module (PM) with SiC MOSFETs and an embedded DC-link decoupling capacitor. In this scheme, multiple Kirchhoff’s laws-based equations are simultaneously solved, and drain-source voltage and drain current are mathematically expressed. This calculation process is semi-theoretical, and sufficiently predicts the Vsurge observed in DPT performed under various conditions.
2019
The modeling method developed in SiC DMOS was applied to the SiC UMOS and its versatility was verified. The model was also evaluated by comparing the switching waveforms fo a power module with SiC UMOS chip. As a result, the SiC UMOS model reproduced the measurement data with high accuracy as well as the SiC DMOS.
The fatigue mechanical property of sintered silver plays a critical role to estimate the reliability of systems. The tensile fatigue test is performed for the sintered silver with p=5% and the bulk silver. The fatigue lifetime of the silver films is shorter than that of the bulk silver one.
Demonstrate the dynamic on-state resistance of GaN-HEMT and estimate inpact of loss of devices.
This study report that high speed switching gate drive circuit for SiC MOSFETs. The provided gate drive circuit adapted subsidery capacitor in order to add gate voltage, enables increase gate current. This allows fast charge and discharge and reduced switching losses. This study confirmed that the provided gate drive circuit reduce switching loss compared to conventional one.
A novel measurement method to extract high voltage and high current I-V characteristics (HVHC I-V)of SiC MOSFET is proposed in this paper. The method could extract the HVHC I-V with extremely reduced self heating of the device. By using the method, we can measure higher voltage and current I-V characteristics than those extracted by the conventional method. It is possible for us to measure the HVHC I-V of the next generation SiC MOSFET, whose rated volatge and current is more than those of the conventional device.
The internal gate resistance of SiC MOSFET effects its switching behavior larger than Si devices because it can switch at high speed with low external gate resistance. However, the convention mesurement method of internal gate resistance is not accurate. Then, we devised the new measurement method of it at switching operation by the switching waveforms.
銀焼成は、空孔率がその引張り機械特性に影響することがわかっている。ところが、銀焼成の疲労機械特性について未だ不明である。今回我々は多孔質銀焼成の薄膜試験片と銀膜の疲労試験を実施した。銀焼成膜は、高加圧条件(60MPa)で成膜し、空孔率は5％であった。疲労試験結果から、焼成膜の引張疲労強度は銀膜と比較して低下しやすいことが分かった。
ロームの高度な分析・解析技術により、PZT薄膜のドライエッチング中に起こる形態変化がPZTの結晶方位が変動する現象に起因することを突き止めた。
SiC,GaNのパワーデバイスを開発するだけでなく、それらを使いこなすための技術も伴わないと社会貢献することはできない。本講演では、アプリケーションの実例、それを支える設計技術、ノイズの予測について紹介する
The precise modeling of SiC MOSFETs are difficult by means of conventional modeling method of Si devices because of the device characteristics. Then, we invented the new modeling method for SiC MOSFETs which can reproduce its switching behavior precisely.
A 3-phase15kW using SiC MOSFETs and trans-linked topology achieved maximum efficiency of 99.2%, and verified the benefit of combining SiC MOSFET with trans-linked technology.
IoT社会では、モノやヒトの状態や変化をセンシングして得られるデータを収集し、生産性や環境の改善、安全や安心の向上、セキュリティの強化等のアプリケーションで活用している。本講演では、デバイスにフォーカスし、IoTアプリケーション事例を述べ、将来技術としてのエネルギーハーベスティングについても述べた。
電流形と電圧形を組み合わせたSiC-MOSFET用ハイブリッド形ゲート駆動回路の実機実験により、ターンオン損失が50%、ターンオフ損失が35%低減できることを実証した。
SiC-MOSFETを高速に駆動できるゲート駆動回路についての報告。本ゲート駆動回路は補助キャパシタを用いており、この補助キャパシタを介してゲートに通常よりも高い電圧を印加することができ、ゲート電流を増加させることができる。これにより高速にゲートを充放電し、スイッチング損失を低減できる。実測でもこの効果を確認し、本回路の優位性を実証した。
2018
This paper investigates the porosity-dependent tensile mechanical properties of porous 8-10 μm thick silver films. The silver films are fabricated by pressure press, the variety of which changes the porosity (p) ranging 5% to 25%. p is determined by use of scanning electron microscopy cross-section images of the films. Stress-strain (S-S) curves are obtained by tensile tests performed for the porous and bulk silver films.Breaking strain and Ultimate tensile strengh decrease almost linearly with increase of p.
SiC,GaNのパワーデバイスを開発するだけでなく、それらを使いこなすための技術も伴わないと社会貢献することはできない。本講演では、アプリケーションの実例、それを支える設計技術について紹介する
Workshop: Introduced RTD devices for THz communication and sensing. With comparison with other terahertz device, RTDs are compact and power-efficient.
接合層の機械特性を取得することが、信頼性システムを設計する上で非常に重要な要因となる。次世代接合材として注目される銀焼成は多孔質体でその機械特性が不明であった。今回我々は多孔質銀焼成の薄膜試験片と銀膜を用意した。また銀焼成膜は、加圧力を変化させて作成している。引張試験結果から、銀焼成は銀膜と異なって伸びずに破壊し、高加圧力条件で高強度を示した。
A number of IoT applications are rapidly growing. Among others, smart factory, smart infrastructure and digital medicine/health are major IoT markets. ROHM also succeeded in demonstration of healthcare monitoring utilizing non-volatile PZT devices. The essentials for IoT society and ROHM’s device applications of PZT thin film were described.
A Scalable drain current model and a small-signal AC model have been developed for AlGaN/GaN MIS HEMTs with embedded source field plate. The model was found to reproduce the device characteristics well by comparing the Id-Vds, Id-Vgs, S11and H21 characteristics of the device.
A trans-linked 5kW interleaved inverter using SiC MOSFETs drastically reduced both tansistor loss and reactor losses, resulting in high efficiency over 99% and fanless operation.
The accurate electro-thermal simulation is presented by using a new SiC die model to predict the power loss and temperature of SiC MOSFET dies in a power module. The new model incorporates a temperature dependent I-V model and body diode model which is dependent on the gate-voltage. The simulation using the model yields an accurate power loss and temperature estimate of the SiC module in a buck converter.
S-parameter based simulation model for power module (PM) except for the semiconductor chips was created with electromagnetic simulation. This PM model was combined with the chip model in order to build the model of the whole structure. As a result of verifying the model by the double pulse test, the simulation waveforms which reproduce the measurement results well were obtained.
ROHM has developed PZT thin film devices, such as non-volatile ferroelectric memory, highly-sensitive sensors, highly-accurate actuators, high-speed space light modulators and ultra-low-power-consumption non-volatile flip-flop devices so far. ROHM also succeeded in demonstration of healthcare monitoring utilizing non-volatile PZT devices (memory and logic). In this presentation, ROHM’s device applications of PZT thin film were described.
We have proposed a new hybrid structure of the PZT film which we made by sol-gel method of construction on the PbTiO3 seed layer made by rf magnetron sputtering. These hybrid PZT films showed high (100)/(001) orientation and had high breakdown voltage.
電流形と電圧形を組み合わせたSiC-MOSFET用ハイブリッド形ゲート駆動回路を提案し、シミュレーションにてゲート電圧の安定性とスイッチング損失の低減ができることを確認した。
The high speed switching of SiC MOSFET is affected by the parasitic elements of circuit board. Therefore, we analyzed the impact of stray capacitance in circuit board on the switching behavior and tried circuit simulation of the effect by use of precise model and electromagnetic simulation results of circuit board.
2017
Present the recent advance of RTD-based terahertz devices. Based on a well-defined equivalent circuit model, circuits like mixer, detector, and oscillators have been integrated.
IoT社会におけるPZTデバイスの位置付けについて述べ、ロームのPZTデバイス技術（メモリからセンサ/アクチュエータ）を概観した。最近の取組み事例として、「不揮発ロジックデバイス」と「ピエゾMEMSデバイス」を紹介した。
This study report that a three-phase, 5-kW LLC series resonant dc/dc converter utilizing SiC MOSFETs. The high-break down voltage of SiC MOSFETs, enables increasing the input voltage up to 800 V. Around 160kHz switchig frequency successfully reduces the volume of isolation transformers. Current-balancing transformers among each phases effectively suppress a peak current from arising in the circuit and contributed that miniaturizes the input and output capacitances. The proposed power supply weighs 1.55 kg with dimensions including a width of 18 cm, a length of 12 cm, and a height of 12.5cm. The conversion efficiency of the converter reaches 98.1% at 5-kW operation.
2016
本講演では、IoTにおけるセンサの重要性を示し、MEMSセンサ、及びIoT/ワイヤレスセンサネットワークについて述べ、更にはアプリケーション開拓に向けた検証としてのセンサソリューションについても述べた。
Progress In Electromagnetics Research Symposium 2016 China
Until now, the transientcharacteristics of circuit simulations using the SiC device model have not been consistent. Since EMC must be considered when using SiC Devices, it is important to reproduce their transient characteristics. Therefore, we have developed a novel SiC devie model by measureing the Id-Vds characteristics with the high-voltage and high-current region and the on-state capacitance of the SiC MOSFET to reproduce the transient characteristics. As a result the novel SiC device model successfully reproduce the switching taransient waveform with high accuracy.
IoT世界においては、トリリオンセンサに代表されるように大量のセンサがネットワークでつながり、暮らしの省エネから快適性・安全性を高めていく。本講演では、各種センサとセンサネットワークへの取り組み、ヘルスケアに必要な常時モニタリングについて紹介した。
2015
The self-sustained oscillations are sometimes obserbed when SiC MOSFETs switch at high speed in the half bridge configuration. The oscillation is regard as nonlinear self-excited oscillation as a result of its device characteristics. We tried to analyze it from the aspects of device characteristics of MOSFET and trajectory of the oscillation in the I-V plane.
