Silicon Insulated Gate Bipolar Transistor Research Articles

Response of commercial Si-IGBT to neutrons and direction dependency

Silicon-insulated gate bipolar transistors (Si-IGBTs) are widely used for power control. In this study, we measured the energy deposited inside a commercial device with neutrons irradiation from 252Cf. We irradiated the device from the sealing and heat sink sides to evaluate the directional characteristics. A radiation simulation analysis was performed to understand the measurement results. The experiment and simulation showed that energy deposition in the device occurs through elastic scattering of neutrons and nuclear reactions. In particular, protons were generated by elastic scattering in the sealing material when the device was irradiated from the sealing side. Thus, the effect of neutrons on commercial Si-IGBTs is due to not only reactions inside the device but also secondary particles from the sealing material. When irradiated with high-energy neutrons, the knocked-out protons from sealing possibly cause single-event burnout (SEB). Therefore, the probability of SEB may depend on the direction of neutron incidence.

Analysis of high‐frequency electromagnetic ringing phenomenon under GaN‐FET inverter excitation

AbstractIn this study, the ringing phenomenon of gallium nitride‐field effect transistor (GaN‐FET) and silicon‐insulated gate bipolar transistor (Si‐IGBT) inverter excitations in a ring sample was thoroughly measured and analyzed by using a high‐quality oscilloscope with a very high sampling rate of 5 giga‐samples per second (GS/s). Owing to the rapid switching of the GaN‐FET power devices in several nanoseconds and the ringing frequencies in the MHz range, the use of the high sampling rate of 5 GS/s is necessary and useful for accurate measurement. The experimental findings and analysis reveal the following three key points: (i) there are two possible types of high‐frequency resonance phenomena, that is, the first one caused by semiconductor devices and circuits and the other generated by the resonance with loads in use. (ii) The ringing phenomenon because of the resonance under the load is considered to be due to the rising time of pulses that are caused by the rapid switching of the semiconductor devices. (iii) The ability to measure and the two types of ringing phenomena depends on the intensity of the white noise of the measuring instrument

Study on stress in trench structures during silicon IGBTs process-oxidation

In silicon insulated gate bipolar transistors, the trench gate structure is used to achieve smaller cell size and lower ON resistance, and thereby reduces energy loss. However, the thermal process can cause large stress near the trench and sometimes degrades device performance. This study proposed a three-dimensional model of a silicon chip with trench structures to analyze the stress distribution induced by thermal process around the trench, the scribe line, and the bottom surface of the chip. The calculated stress is in good agreement with measurement by Raman spectroscopy. The mesa top has much higher stress than the scribe line and the bottom surface. The stress depends on oxide thickness and the size scaling may reduce the stress.

Grid-patterned trench insulated gate bipolar transistor for 1.2 kV hybrid/plug-in hybrid electric vehicle silicon power devices

This paper reports on the newly developed silicon insulated gate bipolar transistor (IGBT) for Toyota’s fifth generation power devices. The designed IGBTs with a grid-patterned trench provide a lower on-state voltage (V ON ) while maintaining a wide mesa width. A successful 15% reduction of V ON was accomplished by enhancement of the two-dimensional hole storage effect. Furthermore, the grid-patterned trench IGBT merged with Schottky and multi-layered anode technology demonstrated a significant improvement in the trade-off curve between the reverse recovery current (I rr ) and V ON in a reverse conducting IGBT without a lifetime control process. As a result, the grid-patterned trench IGBT has contributed to reduce power loss and volume in the new power control units.

Low Inductive Characterization of Fast-Switching SiC MOSFETs and Active Gate Driver Units

Accurate switching device characterization is necessary for effectively utilizing the technological ad-vantages of Silicon Carbide (SiC) Power Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) over their Silicon (Si) Insulated-Gate Bipolar Transistor (IGBT) counterparts. With switching times of few nanoseconds, the unprecedented switching speed of SiC semiconductor devices challenges today's converter and characterization setup designs in regard to parasitic layout inductances for optimal conversion and reliable characterization data. Fur-thermore, active gate driving is a key to unlock the potential of SiC MOSFETs, but requires performance assessment prior to integration. This paper presents a low-inductive test platform for flexible and high-accuracy characterization of fast-switching SiC MOSFETs and active gate drivers evalu-ation. The test circuit delivers high quality characterization data that is comparable with a commercial dynamic power device characterizer. In addition to the conventional hard-switching double-pulse tests with a two-level voltage source gate driver, the test circuit offers soft-switching and gate driver evaluation capability in addition. This test platform is a valuable tool for obtaining reliable characterization data to develop more accurate SiC MOSFET simulation models, and evaluate the combination of gate driver and MOSFET prior to the prototyping phase of a converter.

Performance Comparison of Si IGBT and SiC MOSFET Power Module Driving IPMSM or IM under WLTC

The cumulative inverter losses and power consumption of a silicon insulated gate bipolar transistor (Si IGBT) and three types of silicon carbide metal-oxide-semiconductor field-effect transistors (SiC MOSFETs) were evaluated on an electric motor test bench under a worldwide harmonized light vehicles test cycle (WLTC). SiC MOSFETs showed higher performance than Si IGBT regardless of the motor type and test vehicles. In the case of driving an interior permanent magnet synchronous motor (IPMSM), the latest 4th generation SiC MOSFET (SiC-4G) in ROHM has the lowest inverter loss and energy consumption compared with the other generations. In the case of driving an induction motor (IM), on the other hand, the 2nd generation SiC MOSFET (SiC-2G) in ROHM has the best energy consumption despite the fact that the inverter losses of SiC-2G are slightly larger than the loss of SiC-4G. The latest or later generation power device does not necessarily contribute to better performance in a total system by simply replacing early power devices.

High precision scalable power converter for accelerator magnets

The lower conduction power losses and the positive temperature coefficient that favours parallel connections, make Silicon Carbide (SiC) Metal Oxide Semiconductor Field-Effect Transistors (MOSFETs) to be an excellent replacement of existing Silicon Insulated Gate Bipolar Transistors (IGBTs) technology. These characteristics combined with high switching frequency operation, enables the design of high-accuracy DC-DC converters with minimised filtering requirements. This paper investigates the design for a converter with high-accuracy current (0.9 ppm) supplying a 0.05 H electromagnetic load, aiming to achieve the accuracy without the use of active filters, by using SiC MOSFETs and a scalable module-based converter design.

Hybrid DC Circuit Breaker Using a SiC‐Semiconductor Module at 1 kA Interruption

Hybrid direct current circuit breakers (DCCBs) have become prominent because of their low on‐state power dissipation and small arc erosion compared with conventional semiconductor and mechanical circuit breakers (CBs). After a fault occurs in a DC circuit, the current commutates from the mechanical contacts to the semiconductor devices of the hybrid DCCB, and finally, the current is interrupted by the semiconductor devices. Thus, a low turn‐on voltage or a low on‐state resistance of the devices is needed to reduce the commutation time and power dissipation of the current interruption. This paper presents a comparison of DCCB performances metrics, such as the maximum interruption current, power dissipation, and junction temperature, using a silicon carbide metal‐oxide‐field‐effect transistor (SiC‐MOSFET) and silicon insulated‐gate‐bipolar transistor (Si‐IGBT) module. An interruption of 1.1 kA was achieved in 4.3 ms using the SiC‐MOSFET module of which rated current was 444 A. The junction temperature after the interruption was determined to be 275°C, which exceeded the maximum junction temperature of 175°C. In the case of the Si‐IGBT module of which rated current was 1110 A, the maximum interrupting current was limited to 900 A; however, the maximum junction temperature was 41°C. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Power Performance Comparison of SiC-IGBT and Si-IGBT Switches in a Three-Phase Inverter for Aircraft Applications.

The converters used to integrate the ground power station of planes with the utility grid are generally created with silicon-insulated gate bipolar transistor (Si-IGBT)-based semiconductor technologies. The Si-IGBT switch-based converters are inefficient, oversized, and have trouble achieving pure sine wave voltages requirements. The efficiency of the aircraft ground power units (AGPU) can be increased by replacing existing Si-IGBT transistors with silicon carbide (SiC) IGBTs because of the physical constraints of Si-IGBT switches. The primary purpose of this research was to prove that the efficiency increase could be obtained in the case of using SiC-IGBTs in conventional AGPU systems with the realized experimental studies. In this study, three different experimental systems were discussed for this purpose. The first system was the traditional APGU system. The other two systems were single-phase test (SPT) and three-phase inverter systems, respectively. The SPT system and three-phase inverter systems were designed and implemented to compare and make analyses of Si-IGBTs and SiC-IGBTs performance. The efficiency and detailed hard switching behavior comparison were performed between the 1200-V SiC-IGBT- and 1200-V Si-IGBT-based experimental systems. The APGU system and Si-IGBT modules were examined, the switching characteristic and efficiency of the system were obtained in the first experimental study. The second experimental study was carried out on the SPT system. The single-pulse test system was created using Si-IGBTs and SiC-IGBTs switches in the second experimental system. The third experiment included a three-phase-inverter-based test system. The system was created with Si-IGBTs and SiC-IGBTs to compare the two different switch-based inverters under RL loads. The turning off and turning on processes of the IGBT switches were examined and the results were presented. The Si-IGBT efficiency was 77% experimentally in the SPT experimental system. The efficiency of the third experimental system was increased up to 95% by replacing the old Si transistor with a SiC. The efficiency of the three-phase Si-IGBT-based system was 86% for the six-switch case. The efficiencies of the SiC-IGBT-based system were increased to around 92% in the three-phase inverter system experimentally. The findings of the experimental results demonstrated that the SiC-IGBT had a faster switching speed and a smaller loss than the classical Si-IGBT. As a result of the experimental studies, the efficiency increase that could be obtained in the case of using SiC-IGBTs in conventional AGPU systems was revealed.

LCL-Filter Design Based on Modulation Index for Grid-Connected Three-Level Hybrid ANPC Inverters

This paper proposes an LCL-filter design based on the modulation index for grid-connected hybrid active neutral point clamped (ANPC) inverters. The three-level hybrid ANPC inverter consists of silicon insulated gate bipolar transistors and silicon carbide metal oxide semiconductor field effect transistors to reduce the switching losses. LCL-filter parameters for the three-level hybrid ANPC inverter are calculated using the current ripple factor. The current ripple factor is affected by phase voltage, which varies according to the modulation index, and therefore the inductance on the inverter side must be considered with the modulation index. To design inductance on the inverter side, the output phase voltage and grid voltage are used to analyze the current ripple factor. The filter capacitor and the inductance on the grid side are designed based on the reactive power absorption and current ripple attenuation. The effectiveness of the proposed LCL-filter design method is validated via simulation and experimental results.

Characterization of a 3.3-kV Si-SiC Hybrid Power Module in Half-Bridge Topology for Traction Inverter Application

A state-of-the-art 3.3-kV/450-A hybrid power module for the next generation traction inverter of rolling stock is reported in this paper, combining the silicon (Si) insulated-gate bipolar transistor (IGBT) and silicon carbide Schottky barrier diodes (SBDs) chips. Compared with the existing hybrid technology at the same voltage level, this module is characterized by a half-bridge topology, in which 6 IGBT and 12 SBD chips are integrated in each switch. The outnumbering of the diodes represents a promising mitigation to the low availability of SBDs at this voltage level. Both static and dynamic test of this module and an equivalent Si-based module are carried out comparatively. Apart from describing the features of compactness, low-inductance, and good current distribution among chips, this module is characterized by low turn-ON current overshooting and turn-ON loss of IGBTs, negligible diode reverse recovery time and loss, as well as flexible allowance of IGBT turnON current rising rate dI/dt. A parameterized study is carried out to benchmark the advantage of this new topology. Based on the experimental results, the performance of the hybrid module in a three-phase traction inverter circuit is also evaluated by means of electro-thermal simulation. The hybrid module distinguishes itself by describing much lower power loss and junction temperature than its Si-based counterpart.

Wide-Range Prediction of Ultra-High Voltage SiC IGBT Static Performance Using Calibrated TCAD Model

In this paper, a technology computer-aided design (TCAD) model of a silicon carbide (SiC) insulated-gate bipolar transistor (IGBT) has been calibrated against previously reported experimental data. The calibrated TCAD model has been used to predict the static performance of theoretical SiC IGBTs with ultra-high blocking voltage capabilities in the range of 20-50 kV. The simulation results of transfer characteristics, IC-VGE, forward characteristics, IC-VCE, and blocking voltage characteristics are studied. The threshold voltage is approximately 5 V, and the forward voltage drop is ranging from VF = 4.2-10.0 V at IC = 20 A, using a charge carrier lifetime of τA = 20 μs. Furthermore, the forward voltage drop impact for different process dependent parameters (i.e., carrier lifetimes, mobility/scattering and trap related defects) and junction temperature are investigated in a parametric sensitivity analysis. The wide-range simulation results may be used as an input to facilitate high power converter design and evaluation. In this case, the TCAD simulated static characteristics of SiC IGBTs is compared to silicon (Si) IGBTs in a modular multilevel converter in a general high-power application. The results indicate several benefits and lower conduction energy losses using ultra-high voltage SiC IGBTs compared to Si IGBTs.

A New User-Configurable Method to Improve Short-Circuit Ruggedness of 1.2-kV SiC Power MOSFETs

Silicon carbide (SiC) power MOSFETs have been commercialized to replace silicon insulated gate bipolar transistors (IGBTs) in power conversion applications. However, the short-circuit ruggedness of SiC power MOSFETs must be enhanced to match that of Si IGBTs for application in motor drives for electric vehicles. A new, user-configurable method with a series-connected, Si enhancement mode MOSFET (EMM) is demonstrated to improve the short-circuit withstand time of commercially available 1.2-kV SiC power MOSFETs by 86% with a 4.2% increase in on- resistance and a 13% increase in switching loss. In contrast, operating the 1.2-kV SiC power MOSFET with a reduced gate bias of 15 V produces an 80% improvement in short-circuit withstand time with 31% increase in on- resistance and a 31% increase in switching loss. It is demonstrated that the drain of the EMM can be used as a sensing node to monitor on- state current and to detect short-circuit events.

Exploring SiC Planar IGBTs towards Enhanced Conductivity Modulation Comparable to SiC Trench IGBTs

The state-of-the-art silicon insulated-gate bipolar transistor (IGBT) features a trench gate, since it enhances the conductivity modulation. The SiC trench IGBT, however, faces the critical challenge of a high electric field in the gate oxide, which is a crucial threat to the device’s reliability. In this work, we explore the possibility of using a SiC planar IGBT structure to approach high performance to the level of a SiC trench IGBT, without suffering the high gate oxide field. The proposed SiC planar IGBT features buried p-layers directly under the p-bodies, and thus can be formed using the same mask set. The region between the buried p-layer and the p-body is heavily doped with n-type dopants so that the conductivity modulation is improved. Comprehensive TCAD simulations have been carried out to verify this concept, and the simulation results show the new SiC planar IGBT exhibits a high performance comparable to the trench IGBT, and also exhibits a low gate oxide field.

Fault Diagnosis of Open-Switch Failure in a Grid-Connected Three-Level Si/SiC Hybrid ANPC Inverter

A diagnostic method for an open-circuit switch failure in a hybrid active neutral-point clamped (HANPC) inverter is proposed in this paper. The switching leg of the HANPC inverter consists of four silicon insulated gate bipolar transistors and two silicon carbide metal-oxide-semiconductor field-effect transistors to achieve higher efficiency and power density compared to conventional neutral-point clamped inverters. When an open-circuit failure occurs in a switching device, the output current is severely distorted, causing damage to the inverter and the connected loads. The proposed diagnostic method aims to detect the open-switch failure and protect the related devices without additional sensors or circuits. The faulty conditions of six different switches are investigated based on the current distortion in the stationary reference frame. By analyzing the individual characteristic of each switch failure, it is possible to detect the exact location of the failed switch in a short period. The effectiveness and feasibility of the proposed fault-diagnostic method are verified using simulation and experimental results.

Comparison and Discussion on Shortcircuit Protections for Silicon-Carbide MOSFET Modules: Desaturation Versus Rogowski Switch-Current Sensor

Survivability of silicon-carbide (SiC) mosfet modules during short circuit (SC) is essential for modern power electronics systems due to large economic implications. SiC mosfet modules exhibit narrow SC withstand times and generally much lower SC robustness than silicon (Si) insulated-gate bipolar transistors (IGBTs). This puts a critical concern on their utilization, further stressing the importance of reliable protection. This article presents a comprehensive analysis and discussion on the SiC mosfet module SC protection and performance comparison between conventional desaturation detection, previously used for Si IGBT protection, and Rogowski switch-current sensor (RSCS) detection. In addition, this article presents the experimental design for soft turn-off as a reaction to the SC detection to avoid excessive overshoots during the abrupt turn-off of the SC current. To perform different types of SC with various fault inductances on different temperatures, and for the sake of fair comparison under the same conditions, a gate-driver unit for 1.2 kV SiC mosfet half-bridge modules is developed containing both detection methods. The results demonstrate that both methods are successful in protecting the module in all SC types, with superiority of the RSCS detection and concerns for desaturation detection in high-inductance and high dc-bus voltage SC events.

A Modification of Offset Strip Fin Heatsink with High-Performance Cooling for IGBT Modules

For reliability and thermal management of power devices, the most frequently used technique is to employ heatsinks. In this work, a new configuration of offset strip fin heatsink based on using the concept of curvy fins and U-turn is proposed with the aim of improving the heat transfer performance. With this aim, a three-dimensional model of heatsink with Silicon Insulated-Gate Bipolar Transistors (IGBTs) and diodes, solder, Direct Bonded Copper (DBC) substrate, baseplate and thermal grease is developed. Richardson’s extrapolation is used for increasing the accuracy of the numerical simulations and to validate the simulations. To study the effectiveness of the new offset design, results are compared with conventional offset strip fin heatsink. Results show that in aspects of design of heatsinks (including heat transfer coefficient, maximum chip temperature and thermal resistance), the new introduced model has advantages compared to the conventional offset strip fin design. These enhancements are caused by the combination of the longer coolant passage in the heatsink associated with generation of disturbance and recirculation areas along the curvy fins, creation of centrifugal forces in the U-turn, and periodic breaking up boundary layers. Also, it is shown that due to narrower passage and back-and-forth route, the new introduced design can handle the hot spots better than conventional design.

Digitally Controlled Gate Current Source-Based Active Gate Driver for Silicon Carbide MOSFETs

Silicon carbide (SiC) MOSFETs are viable alternatives for silicon (Si) insulated-gate bipolar transistors (IGBTs). However, direct retrofitting of SiC MOSFETs in Si IGBT-based converters is not feasible due to the presence of a higher amount of parasitic inductance. A large voltage and current overshoot along with oscillation are noticed in such attempts as SiC MOSFETs switch very fast. An active gate driver (AGD) can meet the conflicting requirements of faster switching speed and lower overshoot and ringing. A switched current source-based AGD is designed and extensively tested in a 50-kVA voltage source inverter made with SiC MOSFET power modules. The control methodology is discussed and the experimental results are presented in this article.

A Gate Drive Circuit and Dynamic Voltage Balancing Control Method Suitable for Series-Connected SiC mosfets

Compared with silicon insulated-gate bipolar transistor, silicon carbide (SiC) metal–oxide–semiconductor field-effect transistor ( mosfet ) presents good features that it clearly shows on its switching and thermal performance. However, the fast switching speed of SiC mosfet makes it much more difficult for solving the dynamic voltage imbalance problem caused by the parameter fluctuations of the SiC mosfet s and drive circuits when they are connected in series. This article proposes an effective gate drive circuit and its dynamic voltage balancing control method to tackle this issue. The proposed method not only balances the dynamic voltage during high-speed switching but also adapts to the variation of the dc-bus voltage by utilization of overdrive control method (ODCM). Furthermore, to widen the control range of the ODCM, a switched-capacitor compensation method by switching and combining different drive capacitors into different values is proposed. The operation principles and the parameter design method are discussed in detail. The performance of the proposed series-connected SiC mosfet s gate drive circuit and its dynamic voltage balancing control method is validated by experimental results. The dynamic voltage can be well balanced within the design range.

Achieving Zero Switching Loss in Silicon Carbide MOSFET

Due to the unipolar conduction mechanism, the switching loss of silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (mosfet) is reduced significantly when compared with silicon insulated gate bipolar transistor (IGBT). This enables the use of SiC mosfet in high-frequency application. However, the switching loss could still thermally limit the upper limit of the switching frequency. Further reduction of switching loss of SiC mosfet, therefore, remains an open challenge for higher frequency applications. Based on the in-depth revelation of device physics of the switching process, accurate switching loss model is established which highlights the dependence of the switching loss on the gate driving condition. With extreme fast gate driving condition, several loss limitations can be established. The minimum turn-on loss is the energy stored in the output capacitance and the minimum turn-off loss can approach zero or the so-called zero turn-off loss (ZTL). Furthermore, zero switching loss (ZSL) is achieved when utilizing zero-voltage switching turn-on and ZTL turn-off condition. With ZSL, the upper limit of the switching frequency is no long thermally limited which is verified by co-package experimental demonstration. We believe the trailblazing concepts of SiC mosfet switching loss will provide guiding principles for device innovation, package optimization, gate driver improvement, and current possible solutions toward higher frequency applications.