Silicon Carbide Power Module Research Articles

A Novel Double-Sided Cooling Silicon Carbide Power Module With Ultralow Parasitic Inductance Based on an Interleaved Power Loop

A Novel Double-Sided Cooling Silicon Carbide Power Module With Ultralow Parasitic Inductance Based on an Interleaved Power Loop

Multichip Parallel Double-Sided Cooling Silicon Carbide Power Module With Low Parasitic Inductance and Balanced Dynamic Current

Multichip Parallel Double-Sided Cooling Silicon Carbide Power Module With Low Parasitic Inductance and Balanced Dynamic Current

Power Cycling Performance of 3.3 kV SiC-MOSFETs and the Impact of the Thermo-Mechanical Stress on Humidity Induced Degradation

Recently, silicon carbide (SiC) power modules of the 3.3 kV voltage class became available and are a promising candidate to replace silicon power modules in traction applications. However, the more than three times higher Young’s Modulus compared to silicon leads to a reduced lifetime under thermo-mechanical stress. This could pose a significant obstacle in their implementation, since traction applications are particularly demanding in their mission profiles with respect to load cycling, but also to environmental conditions. Thus, the thermo-mechanical stress is not just limiting the lifetime itself, but might also promote the humidity induced degradation due to delamination or micro-cracks. In this work, multiple power cycling tests at different temperature swings on 3.3 kV SiC MOSFET chips in a power module were performed, to assess their ruggedness under thermo-mechanical stress. Before or afterwards, these modules were tested under standard HV-H3TRB conditions to verify the interaction between thermo-mechanical and humidity stress on the robustness of the modules.

High-Pressure-Assisted Large-Area (>2400 mm2) Sintered-Silver Substrate Bonding for SiC Power Module Packaging.

The emergence of new semiconductor devices puts forward higher requirements for packaging technology. Sintered silver technology has gradually developed into critical packaging technology in silicon carbide power module packaging due to its good heat dissipation performance and reliability. However, high sintering drive requirements, low sintering densification, and high thermal-mechanical stresses limit the application of sintered silver technology for large-area bonding. In this study, the high-pressure-assisted (≥10 MPa) large-area sintered-silver interconnection process between a substrate and baseplate was discussed. C-scan acoustic microscopy, warpage testing, and microanalysis were used to analyze the effects of drying methods, sintering pressure, and holding time on the sintered joints, and thermal fatigue reliability tests were conducted on large-area sintered silver joints. The results demonstrated that the quality of large-area sintered joints obtained via open-face convective drying is higher than that via close-face convective drying. Combining the performance of sintered joints and productivity, the recommended process condition is determined as follows: open-face convective drying, sintering temperature of 250 °C, sintering pressure of 15 MPa, and holding time of 5 min. Large-area sintered joints have outstanding reliability, with slight delamination of the sintered layer at the corners and no cracking after 1000 cycles of temperature cycling.

Development of a steady state electrothermal cosimulation model of SiC power modules

Silicon carbide power modules are suitable for high temperature, high voltage and high frequency applications. High operating temperature and high power density bring enormous challenges in chip parallel connection and junction temperature predicting. In this work, a steady state electrothermal cosimulation model is established based on Matlab electrical model and ANSYS thermal analysis model. An experimental study is conducted using a customized single die SiC module. The experimental and numerical results exhibit great agreement, with deviation consistently below 4 %. Then, comprehensive research is conducted to investigate the electrothermal performance of several dies in parallel configuration. The findings unequivocally validate the efficacy of the proposed model in accurately capturing the intricate electrical and thermal characteristics. The proposed numerical model offers a reliable and accurate electrothermal modeling approach for SiC power modules.

Power Cycling Reliability with Temperature Deviation of Pressureless Silver Sintered Joint for Silicon Carbide Power Module

SiC devices can enhance power conversion in electric vehicles. However, traditional soldering techniques are limited by their low melting temperatures. Therefore, we used pressureless Ag sintering to assemble a 1200 V/200 A SiC metal-oxide-semiconductor field-effect transistor power module and compared the long-term reliability, electrical properties, and driving performance of the module with those of a similar module assembled using the solder Sn-3.0Ag-0.5Cu (SAC305). To assess sinter joint reliability, we performed power cycling tests over two temperature ranges, 50–150°C and 50–175°C, for 15,000 cycles. Subsequently, we compared the breakdown voltage (BVDSS) and drain-source on-resistance (RDS(ON)) of the SiC power modules and performed cross-sectional analyses of the device bonding interfaces. No difference in BVDSS was found between the Ag-sintered and SAC305-soldered joints. However, the RDS(ON) exhibited minimal variation for the Ag-sintered module but significantly varied for the SAC305-soldered module, suggesting that the former better maintained its characteristics. Furthermore, the electrical characteristics of the SAC305-soldered module underwent more significant alterations with increasing temperature change during power cycling, indicating that cracks propagated throughout the SAC305 soldered joint over time. Therefore, Ag sintering was quantitatively validated as the superior die attachment technology compared to soldering for long-term reliability.

State-of-the-Art Medium- and High-Voltage Silicon Carbide Power Modules, Challenges and Mitigation Techniques: A Review

State-of-the-Art Medium- and High-Voltage Silicon Carbide Power Modules, Challenges and Mitigation Techniques: A Review

An Effective Current Balancing Method for Inverters With Paralleled Silicon Carbide Power Modules

An Effective Current Balancing Method for Inverters With Paralleled Silicon Carbide Power Modules

Silicon carbide based traction inverter cooling in electric vehicle using heat pipes

Power train in electric vehicles is provided with assortment of power electronics including traction inverter to control, monitor and deliver electric power from battery system to electric motor as per vehicle needs. Inverter technology based on Silicon Carbide (SiC) semiconductor provide lower switching losses, can handle high power densities and can operate at very high junction temperatures ∼ 200 °C, which enables air cooling for such system viable. This project investigates the technical feasibility and the potential of an air-cooled traction inverter, for mid-sized passenger vehicles, with very high heat fluxes (∼35 W/cm2) and heat loads exceeding ∼ 2.2 kW. Heat pipe based air cooled heat sink has been evaluated for thermal management of SiC inverter for traction purposes in electric vehicles. Traction inverter was equipped with 3x SiC power modules, each with 350 W heat load (∼17 W/cm2 heat flux) totaling 1050 W, and operating in 85 °C ambient. Based on analysis of different design options, remote heat pipe heat exchanger was chosen as optimal design with best performance and volume/area ratio. Heat pipe system with copper–water heat pipe configuration and air cooled aluminum sheet metal based heat sink arrangement was designed in segmented form to dissipate asymmetric heat loads (65 % top, 35 % bottom) output by two faces of each SiC power module. Top surface of each chip was cooled by separate heat sink, each with 2x U-shape heat pipes while bottom faces of three chips have common heat sink with 6x L-shape heat pipes. Complete cooling system was put together using system of copper blocks that provide housing for SiC power modules while allowing for integration of cooling module into inverter housing, keeping IP6 K4K sealing requirements. Proposed solution was able to keep junction temperature < 142 °C against requirement of 175 °C, provide thermal uniformity within ∼ ±5 °C, was able to handle maximum power surges double of nominal loads, qualify for start-up from frozen state and was able to handle temperature cyclic loading without showing any performance degradation. Heat pipe based air cooling system for traction inverter, in particular, and overall vehicular power electronics, in general, will provide dedicated and modular cooling system approach, which can be located with relative ease and simplicity as compared to liquid cooled system while achieving lower system cost. Furthermore, such systems will provide operational safety against leaks, runtime reliability and lifetime longevity which is critical in automotive.

Structure and the Thermal Management of a 3-D Silicon Carbide MOSFET Module

Silicon carbide (SiC) device has higher switching frequency, higher breakdown voltage, and lower on-state voltage drop, which makes it subversive potential in the high power density applications. However, the traditional packaging structure cannot cope with the high power density of SiC devices, so the existing commercial SiC power module can only be used in derating applications. This paper proposed a 3-D packaging design method for high power density MOSFET power module, in which the cooling system is integrated inside the module to reduce the thermal resistance and the temperature difference of the SiC MOSFET chips. At the same time, the heat dissipation process of the new structure is modeled and analyzed, and the accuracy of the model is proved by experiment and simulation.

FEA-Dominant Reliability and Lifetime Model of Double-Sided Cooling SiC Power Module

Owing to the low parasitic inductance, high power density, and excellent heat extraction performance, double-sided cooling (DSC) is regarded as a promising packaging solution for the silicon carbide (SiC) power module. Nevertheless, given the unclear failure mechanism and missed lifetime model, the reliability assessment and lifetime prediction of the DSC SiC power module remains a concern. Besides, the accelerated aging test generally used for the reliability assessment of the SiC power module is extremely time-consuming and costly. Therefore, the obstacles mentioned before limit the development and deployment of the DSC SiC power module. Aiming to fulfill these research gaps, based on the aging mechanism and failure criterion of packaging materials, the lifetime model of the DSC SiC power module is proposed in this paper. Comparative experiments show that the relative error of the FEA-dominated model is less than 6%. Moreover, the stress property and creep principle of the solder layer in SiC and Si power modules are assessed, respectively. Besides, the lifetime models of SiC and Si power modules applying different packaging materials are created. It is found that the lifetime of the DSC power module is twice that of the single-sided cooling (SSC) counterpart. Furthermore, applying the same packaging, the lifetime of the SiC power module decreases by 70% compared with the Si counterpart. In addition, the lifetime of the DSC SiC power module affected by different materials such as ceramic and spacer is studied in order to enhance its reliability.

A High Power Density Double-Side-End Double-Sided Bonding SiC Half-Bridge Power Module

Silicon Carbide (SiC) power module with lower loop inductance, better dynamic current sharing properties and better thermal performance will contribute to achieve high power density three phase inverter in medium voltage applications. Inspired by the concept of double-side-end busbar, a novel double-side-end double sided bonding power module is proposed in this paper. For three chips parallel situation, double-side-end structure decreases parasitic inductance by 40% compared to that of traditional baseline structure. Besides lower parasitic inductance, novel structure also has better dynamic current sharing properties. To explain these dynamic current sharing phenomena, an equivalent source inductance model considering mutual inductance is proposed in this paper. A 1200V 10mΩ SiC double-side-end double sided bonding half-bridge power module is designed, fabricated and tested. Proposed power module realizes 3nH power loop inductance. Furthermore, to realize practical application of the novel power module, a novel compact two-level three-phase integration architecture based on novel power module is also proposed. With the help of the double-sided direct-cooling method and double-side-end busbar, proposed architecture will help to realize better performance.

High Temperature Characteristics of Composite Materials Composed of Silicone Gel and Barium Titanate in High Voltage Power Modules

The blocking voltage of silicon carbide (SiC) device is greater than 10 kV. High voltage can cause high electric field inside SiC power module. Improving the insulation properties of the encapsulation material of power module becomes an urgent requirement. The electrical field-dependent permittivity (FDP) material composed of silicone gel and barium titanate (BaTiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) can be used to reduce the high electric field. However, the related research on FDP materials is limited to the room temperature conditions. It is not enough since the operating temperature of power module is higher than the room temperature because of the power loss, and the temperature has a great influence on the performance of FDP material. This paper focuses on the high temperature performance of this composite material in reducing electric field. Firstly, the simulation results show that the triple point between metallization, ceramic and silicone gel is both stressed by high electric field and high temperature. Increasing the dielectric permittivity of the encapsulation material can reduce electric field stress. Secondly, the breakdown voltage and aging properties of silicone gel and the composite were analyzed. The Curie temperature of the FDP material was measured experimentally, which proved that the Curie point of the FDP material would not be changed by the silicone gel. Thirdly, the permittivity of FDP material at different temperatures and the mechanism of reducing the electric field stress are investigated.

Multiscale Electrothermal Design of a Modular Multilevel Converter for Medium-Voltage Grid-Tied Applications

As a key feature of modular multilevel converters (MMCs), a large number of semiconductor devices are employed in the converter and distributed over a stack of submodules. Each submodule has a strict temperature limit that imposes constraints on the operating range of the converter. Different loading conditions/losses in the submodules lead to unavoidable temperature variations inside the MMC, which consequently affect the system-level performance and reliability. This paper is focused on the electrothermal analysis and design of a medium-voltage silicon carbide (SiC)-based MMC system, from submodule power semiconductors to the overall MMC system integration of multiple submodules, for grid-connected applications. Loss calculations are performed to estimate the cooling requirements and aid thermal design at different levels. The performance of a forced-air cooling approach is analyzed within a numerical modeling framework. Maximum temperature of the SiC power modules is predicted using numerical tools. Thermal design of the MMC cabinet with various arrangements of air inlet(s) and outlet(s) is investigated and compared from a cooling performance perspective. A fully resolved model of the arrangement that yields optimal results is developed to accurately predict the temperature profile of the essential components in the submodules.

Single-Phase Jet Impingement Cooling for a Power-Dense Silicon Carbide Power Module

The adoption of silicon carbide (SiC) devices in the electric vehicle (EV) industry is increasing due to their superior performance over silicon devices. SiC devices enable further miniaturization of EV inverters, increasing their power density, which results in thermal management challenges. In this paper, the limits of single-phase jet impingement cooling are explored for an automotive SiC power module. We propose embedding pin fins in the direct-bonded-copper (DBC) substrate of the power module package using laser powder bed fusion additive manufacturing. The thermalhydraulic performance of the DBC-embedded pin fins is compared against folded fins that are directly soldered to the DBC substrate. A heat conduction analysis was conducted on a SiC package to determine the target heat transfer coefficient (HTC) for the heat sink. A water-ethylene glycol (WEG) jet impingement on the proposed concepts was studied using unit-cell models to achieve the target HTC. The studied designs put emphasis on the reliability and manufacturability requirements of the automotive industry. The thermal performance of DBC-embedded pin fins outperformed the DBC-soldered folded fins. The performance of the DBC-embedded pin fins is benchmarked against WEG-based cooling systems of commercial EVs. With the proposed cooling solution, we have shown a pathway of reducing the specific thermal resistance by 75% compared to BMW i3 thermal management system without any penalty on pressure drop or parasitic power.

A Highly Integrated Multichip SiC MOSFET Power Module With Optimized Electrical and Thermal Performances

This paper proposes a highly integrated multichip silicon carbide (SiC) MOSFET power module packaging with optimized electrical and thermal performances. The structure of the module is to stack the two power switches up and down with the cooling system and the decoupling circuit integrated inside the module. The structural characteristics of the module realize the co-optimization of the switching performance, thermal management, and electromagnetic interference (EMI) issue of the multichip SiC module, which effectively solve the contradiction in the optimization of the electrical and thermal performance. In addition, by optimizing the process flow and designing a variety of soldering fixtures, the feasibility of the process and the engineering margin is increased. Experiments and simulations show that the proposed SiC power module has good electrical and thermal performance. The loop parasitic inductance is reduced to 2.02 nH and the common-mode (CM) current is eliminated. The drain–source voltage overshoot during the turn-off transient is reduced by 76.5%, and the voltage oscillation is significantly improved due to the integration of the decoupling circuit. At the same time, the integrated liquid-cooling heatsink greatly improves the cooling efficiency of the module on the premise of ensuring the insulation performance of the module.

Design and Evaluation of a Face-Down Embedded SiC Power Module With Low Parasitic Inductance and Low Thermal Resistance

This letter proposed an embedded silicon carbide (SiC) power module with low parasitic inductance and low thermal resistance for high-frequency and high-temperature applications. The SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s were oriented in a face-down configuration with Cu connecting blocks, contributing to better switching performance and heat dissipation. The simulation results showed that the total parasitic inductance was lower than 300 pH. Double pulse test and thermal resistance experiments compared with a commercial package showed that the switching loss and the junction-to-case resistance of the proposed module were reduced by 23% and 35%, respectively.

Real-Time FPGA Simulation of High-Voltage Silicon Carbide MOSFETs

This article presents a real-time field-programmable gate array (FPGA)-based dynamic model of high-voltage and high-current silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor ( <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> ) half-bridge power modules. The dynamic switching model utilizes the Shichman and Hodges equations using voltage-dependent nonlinear device capacitances and module electrical parameters to obtain an accurate dynamic model of the device switching transients. The key device states gate-source voltage, drain current, and drain-source voltage are modeled and discretized using forward Euler discrete integration method. Analysis of synthesizing the discrete-time model into real-time FPGA-based system with real-time data output from the on-board digital-to-analog converter is presented in detail. The model is utilized in modeling a 320-kW, medium-voltage dc/dc dual-active bridge converter and verified using dynamic experimental results from a 3.3-kV SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> half-bridge power module. It has been shown that the presented discrete-time dynamic switching model accurately describes the turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> switching transients of the SiC power module at various voltage and current levels. Such models are useful for rapid and cost effective design and prototyping of SiC-based power electronic systems by defining key design and operating parameters, such as deadtime, switching frequency, and switching losses.

Knowledge is Power

Experts from two firms leading the way in developing new silicon carbide power modules for traction, Mitsubishi Electric and Microchip Technology, reveal how SiC technology can help rail operators reduce energy losses and improve reliability and efficiency, while minimizing their impact on the environment

Layout-Dominated Dynamic Current Balancing Analysis of Multichip SiC Power Modules Based on Coupled Parasitic Network Model

Multichip silicon carbide (SiC) power modules with Kelvin-source connections are commonly used in applications requiring large capacity. As a result of the parasitic effect induced by the interconnections in module packaging, the dynamic current mismatch among paralleled dies limits the available capacity of power modules. This article presents a general analysis on the mechanism of layout-dominated dynamic current balancing in multichip SiC power modules, utilizing a coupled parasitic network model. Focusing on the interrelation of parasitic parameters in the power module, a coupled parasitic network model is developed specially for switching transients, and the dynamic current balancing equations are derived. For the multichip power modules with two different layouts, the parasitic parameters pertaining to the proposed model are extracted by the finite-element analysis (FEA). The acquired parasitic parameters considering magnetic coupling are utilized to calculate and verify the dynamic current balancing equations. Moreover, based on these parasitic parameters, the electromagnetic coupling simulation is performed to evaluate the dynamic current sharing. Furthermore, for the validation of the proposed model and equations, experiments are conducted with the fabricated power module prototypes.