Silicon Carbide Power Module Research Articles

Single‐Stage ZVS‐PWM AC‐AC Power Converter Using All SiC Power Module for High‐Frequency Induction Heating Applications

SUMMARYThis paper presents a novel prototype of a single‐stage zero voltage soft‐switching pulse‐width modulation ‐controlled ac‐ac converter with a silicon carbide (SiC)‐MOSFET/SiC‐SBD power module for high‐frequency (HF) induction heating (IH) applications. The newly developed ac‐ac converter can achieve higher efficiency than a Si‐IGBT/Si‐PN diode power module‐based prototype due to a low ON‐resistance of SiC‐MOSFET and a low forward voltage of SiC‐SBD under the condition of HF switching. The performances of the new prototype converter are evaluated by experiment with a single‐phase IH utensil of ferromagnetic stainless metal, after which the high‐efficiency and low switching noise characteristics due to the all SiC power module are actually demonstrated.

An Accurate Subcircuit Model of SiC Half-Bridge Module for Switching-Loss Optimization

The increasing demand for high power density requires the power converter to operate in high switching frequency. Silicon carbide (SiC) power module is regarded as one of the most promising candidates for high-frequency applications due to the superior switching speed and low switching loss. With the increase of switching frequency, the switching loss will be the limiting factor of efficiency. Hence, it should be minimized during each switching transition. The optimization of switching loss is normally achieved by the repetitive double pulse test experiments. It is time-consuming to find an optimum gate resistance to achieve the tradeoff between switching loss and electromagnetic interface. In this paper, an accurate subcircuit model for SiC power module is proposed to assist optimization of switching loss in converter design. By considering the device physics and structure, an accurate Miller capacitance model is obtained. Moreover, a parameter extraction procedure is presented, which is based on the datasheet. Good agreements are achieved between the PSpice simulation and experiment.

Evaluation of Thermal Resistance Degradation of SiC Power Module Corresponding to Thermal Cycle Test

Abstract In this paper, we demonstrate that thermal degradation of silicon carbide (SiC) power modules corresponding to thermal cycles can be detected and tracked non-destructively by transient thermal analysis. The purpose of this evaluation is to analyze the distribution of the thermal resistance in the power module and to identify the structure deterioration part. As a target for evaluation power modules using a SiC-MOSFET for high-temperature operation were assembled with Zn-5Al eutectic solder. The junction to case thermal resistance was successfully evaluated as 0.85 K/W by using transient thermal analysis, and the thermal resistance of the Zn-5Al die-attachment was also evaluated as 0.13 K/W. A series of thermal cycle test between −40 and 250°C was conducted, and the power modules were evaluated their thermal resistance taken out from thermal cycle test machine at 100, 200, 500 and 1000 cycles. We identified the increase of thermal resistance each thermal cycle in specific modules. It was successfully shown that thermal resistance deterioration of SiC power module corresponding to thermal cycles can be traced non-destructively by this transient thermal analysis method.

High Performance Silicon Carbide Power Packaging—Past Trends, Present Practices, and Future Directions

This paper presents a vision for the future of 3D packaging and integration of silicon carbide (SiC) power modules. Several major achievements and novel architectures in SiC modules from the past and present have been highlighted. Having considered these advancements, the major technology barriers preventing SiC power devices from performing to their fullest ability were identified. 3D wire bondless approaches adopted for enhancing the performance of silicon power modules were surveyed, and their merits were assessed to serve as a vision for the future of SiC power packaging. Current efforts pursuing 3D wire bondless SiC power modules were described, and the concept for a novel SiC power module was discussed.

Mission-profile-based stress analysis of bond-wires in SiC power modules

This paper proposes a novel mission-profile-based reliability analysis approach for stress on bond wires in Silicon Carbide (SiC) MOSFET power modules using statistics and thermo-mechanical FEM analysis. In the proposed approach, both the operational and environmental thermal stresses are taken into account. The approach uses a two-dimension statistical analysis of the operating conditions in a real one-year mission profile sampled at time frames 5min long. For every statistical bin corresponding to a given operating condition, the junction temperature evolution is estimated by a thermal network and the mechanical stress on bond wires is consequently extracted by finite-element simulations. In the final step, the considered mission profile is translated in a stress sequence to be used for Rainflow counting calculation and lifetime estimation.

Analysis of Parasitic Elements of SiC Power Modules With Special Emphasis on Reliability Issues

Commercially available silicon carbide (SiC) MOSFET power modules often have a design based on existing packages previously used for silicon insulated-gate bipolar transistors. However, these packages are not optimized to take advantage of the SiC benefits, such as high switching speeds and high-temperature operation. The package of a half-bridge SiC MOSFET module has been modeled and the parasitic elements have been extracted. The model is validated through experiments. An analysis of the impact of these parasitic elements on the gate-source voltage on the chip has been performed for both low switching speeds and high switching speeds. These results reveal potential reliability issues for the gate oxide if higher switching speeds are targeted.

Electro-thermal simulation of current sharing in silicon and silicon carbide power modules under short circuit condition of types I and II

Current sharing during short circuit events of types I and II has been investigated by electro-thermal compact simulation of semiconductor devices paralleled in a 650V power module. The response of silicon IGBTs has been compared to that of silicon carbide MOSFETs. The study of current unbalance due to symmetrical and asymmetrical interconnect topologies has been followed by isothermal and full electro-thermal simulation of the power modules. It has been shown that replacing in the simulation the active devices within the module by resistors leads to misleading results, because the current unbalance under short circuit conditions is mainly due to the difference in the gate-source/gate-emitter voltage among the individual paralleled devices. Finally, it has been demonstrated that in the investigated power modules, self-heating contributes to the mitigation of current unbalance.

Liquid Jet Impingement Cooling of a Silicon Carbide Power Conversion Module for Vehicle Applications

Thermal management of power electronics is an extremely challenging problem in the harsh environment of military hybrid vehicles, where the local air and liquid coolant's temperature exceed 100 °C under regular operating conditions. This paper presents the development work of a high heat flux, jet impingement-cooled heat exchanger for a 600-V/50-A silicon carbide (SiC) power module (rated at 175 °C device junction temperature), used for bidirectional power conversion between a 28-V battery and a 300-V dc bus. A total of 50 volume% mixture of water–ethylene glycol (WEG) coolant at 100 °C inlet temperature is the only available coolant. An array of WEG coolant microjets impinges on the base plate of the SiC module. The jet impingement cooling system has been optimized by experimental studies on a surrogate module, along with a high-fidelity computational model, to accurately estimate the SiC device junction temperature in relevant operating conditions. Results indicate that at the design heat load of 151 W (worst-case scenario), the SiC device junction temperature is reduced from 290 °C with commercial-off-the-shelf (COTS) cold plate cooling and 215 °C with COTS microchannel heat exchanger cooling, to 169 °C with a jet impingement-cooled heat exchanger, using the same flow rate.

A high temperature silicon carbide mosfet power module with integrated silicon-on-insulator-based gate drive

This paper presents a board-level integrated silicon carbide (SiC) mosfet power module for high temperature and high power density application. Specifically, a silicon-on-insulator (SOI)-based gate driver capable of operating at 200 °C ambient temperature is designed and fabricated. The sourcing and sinking current capability of the gate driver are tested under various ambient temperatures. Also, a 1200 V/100 A SiC mosfet phase-leg power module is developed utilizing high temperature packaging technologies. The static characteristics, switching performance, and short-circuit behavior of the fabricated power module are fully evaluated at different temperatures. Moreover, a buck converter prototype composed of the SOI gate driver and SiC power module is built for high temperature continuous operation. The converter is operated at different switching frequencies up to 100 kHz, with its junction temperature monitored by a thermosensitive electrical parameter and compared with thermal simulation results. The experimental results from the continuous operation demonstrate the high temperature capability of the power module at a junction temperature greater than 225 °C.

High-Heat-Resistance Polymers for SiC Power Modules

Power semiconductor devices are critical to CO2-reduction technology. In this study, we focus on a silicon carbide (SiC) device with a wide bandgap (WBG), which operates with low loss and high efficiency at temperatures up to 300°C. Conventional isolation/sealing technologies are unable to cope with such high operating temperatures; therefore, new advanced materials are necessary. In this report, we introduce SiC power module platforms to evaluate an alternative technology involving various encapsulating materials, bonding materials, and techniques for assembly. We attempted to produce four types of platforms, PT-1 through PT-4. Fig. 1 presents the cross section and a photograph of the platform PT-3, which was assembled from a Si insulated-gate bipolar transistor (IGBT) and a SiC diode. A simulation analysis was performed to evaluate the optimum properties of the platforms from the viewpoint of their reliabilities. The purpose of this project is to accelerate the development of high-heat-resistance materials and bonding technologies through the abovementioned evaluation platforms. We identify this project as “KAMOME-PJ (Kanagawa Advanced Module for Material Evaluation).” As a pertinent example, we report a novel polymer alloy having both high heat resistance and low thermal expansion (CTE). This alloy was prepared by melt mixing of two compounds,bismaleimide diphenyl methane (BMI) and 3,3’-(methylen-1,4-diphenylen) -bis(3,4-dihydro-2H-1,3-benzoxazine) (P-d). The resin comprising BMI 1.0 vs. P-d 0.3 exhibited superior thermal properties and processability. When cured at only 200°C for 4 h, the glass transition temperature of the resulting product was above 300°C. An encapsulation material was prepared using this polymer alloy, whose properties are described in Table 1 and are compared to those of conventional epoxy materials.

Development of Advanced All-SiC Power Modules

A thermally integrated packaging structure for an all silicon carbide (SiC) power module was used to realize highly efficient cooling of power semiconductor devices through direct bonding of the power stage and a cold baseplate. The prototype power modules composed of SiC metal-oxide-semiconductor field-effect transistors and Schottky barrier diodes demonstrate significant improvements such as low-power losses and low-thermal resistance. Direct comparisons to their silicon counterparts, which are composed of insulated gate bipolar transistors and PiN diodes, as well as conventional thermal packaging, were experimentally performed. The advantages of this SiC module in efficiency and power density for power electronics systems have also been identified, with clarification of the SiC attributes and packaging advancements.

1000-H Evaluation of a 1200-V, 880-A All-SiC Dual Module

The commercial availability of silicon-carbide (SiC) power devices began over a decade ago with the introduction of SiC diodes and has expanded in complexity the past few years to include the offering of SiC transistors and power modules. Recently, characterization of a 1200-V, 800-A all-SiC dual module designed for large-scale electric military vehicle applications has been reported. This paper expands on the previous work by presenting details and results obtained from a long-term evaluation of a similar module. The module has successfully operated in an experimental circuit at a switching frequency of 10 kHz while running vehicle load profiles for over 1000 h and exhibited little change in device characteristics. Of all measured characteristics, none had a significant unfavorable change greater than 10% from its initial value. The 1000 h of circuit operation represents 11 783 miles of use or over half of the expected lifecycle in a military vehicle traction inverter.

Development of High Power Density Three-Phase Inverter

A high power density three-phase unit with the forced-air cooling, which has 10kW power capacity, is developed in this report. The high power three-phase unit is composed of three SiC(Silicon Carbide) power module, cooling fan, DC capacitor, gate-drive circuit, and EMI filter. And also, the design method and the evaluations of the power module, cooling system, gate-drive circuit, and EMI filter are discussed in case that the switching frequency is 50kHz. The volume of the DC/AC converter, EMI filter, and device temperature in the rated output are respectively designed to become 220 degree, 250cc, and 120cc.

Precise Chip Joint Method with Sub-micron Au Particle for High-density SiC Power Module Operating at High Temperature

In this work, a novel precise chip joint method using sub-micron Au particle for high-density silicon carbide (SiC) power module operating at high temperature is proposed. A module structure of SiC power devices are sandwiched between two silicon nitride-active metal brazed copper (SiN-AMC) circuit boards. To make a precise position and height control of the chip bonding, the top side (gate/source or anode pad side) of SiC power devices are flip-chip bonded to circuit electrodes using sub-micron Au particle with low temperature (250°C) and pressure-less sintering. The accuracy of the bonding position of chips was less than 10 μm and the accuracy of the height after bonding chips was less than 15 μm. Mechanical shear fatigue tests for flip-chip bonded SiC Schottky barrier diode (SBD) were carried out. As a result, initial shear strength of the joint was 36 MPa. The shear strength of 43 MPa is obtained after storage life test (500 hours at 250°C), and also 35 MPa is obtained even after thermal cycle stress test (1000 cycles between −40°C and 250°C). The flip-chip bonding of SiC-JFET is successfully realizedon the substrate without short or open failure electrically. Finally we joint the backside of the SiC-JFET (drain side) and the SiC-SBD (cathode side) to each circuit electrodes at once by means of reflow process with Au-12%Ge solder. The structured sandwich SiC power module was also successfully formed.

High Temperature Silicon Carbide Power Modules for High Performance Systems

The demands of modern high-performance power electronics systems are rapidly surpassing the power density, efficiency, and reliability limitations defined by the intrinsic properties of silicon-based semiconductors. The advantages of silicon carbide (SiC) are well known, including high temperature operation, high voltage blocking capability, high speed switching, and high energy efficiency. In this discussion, APEI, Inc. presents two newly developed high performance SiC power modules for extreme environment systems and applications. These power modules are rated to 1200V, are operational at currents greater than 100A, can perform at temperatures in excess of 250 °C, and are designed to house various SiC devices, including MOSFETs, JFETs, or BJTs.

(Invited) Packaging and Modeling of SiC Power Modules

This paper presents the latest advancements in silicon carbide (SiC) power module packaging. Die attach methods, passivation techniques, and module packaging techniques for multiple-chip power modules are described. The most recent work involving high voltage/high current modules for a SiC fault current limiter rated at 8 kV and 400 A continuous current is described. A roadmap to address outstanding challenges is proposed.

High Temperature Silicon Carbide Power Modules for High Performance Systems

The demands of modern high-performance power electronics systems are rapidly surpassing the power density, efficiency, and reliability limitations defined by the intrinsic properties of silicon-based semiconductors. The advantages of silicon carbide (SiC) are well known, including high temperature operation, high voltage blocking capability, high speed switching, and high energy efficiency. In this discussion, APEI, Inc. presents two newly developed high performance SiC power modules for extreme environment systems and applications. These power modules are rated to 1200V, are operational at currents greater than 100A, can perform at temperatures in excess of 250 °C, and are designed to house various SiC devices, including MOSFETs, JFETs, or BJTs. One newly developed module is designed for high performance, ultra-high reliability systems such as aircraft and spacecraft, and features a hermetically sealed package with a ring seal technology capable of sustaining temperatures in excess of 400°C. The second module is designed for high performance commercial and industrial systems such as hybrid electric vehicles or renewable energy applications, implements a novel ultra-low parasitic packaging approach that enables high switching frequencies in excess of 100 kHz, and weighs in at just over 130 grams (offering ~5× mass reduction and ~3× size reduction in comparison with industry standard power brick packaging technology). It is configurable as either a half or full bridge converter. In this discussion, APEI, Inc. introduces these products and presents practical testing of each.

Developments in Hybrid Si – SiC Power Modules

This paper investigates utilization of silicon carbide (SiC) Schottky power diodes as inverter Free Wheel Diodes (FWD) in a commercially available standard Econopak module also packaged with latest generation low-loss IGBT silicon. Static and switching characteristics of SiC diodes over standard module operating temperature 25 0C to 125 0C (298 0K - 398 0K) are measured. Module Turn-on, Turn-off and conduction losses vs. frequency are calculated and measured for three phase motor drive operation. Measurements are compared to standard modules using all Silicon (Si) IGBT- diode. System benefits justifying the increased SiC diode cost, such as EMI reduction, increased efficiency, reduced magnetic filter volume and reduced cooling requirements at higher allowable switching frequencies is investigated.

Design and technology of compact high-power converters

New material technologies such as Silicon Carbide (SiC) are promising in the development of compact high-power converters for next-generation power electronics applications. This paper presents an optimized converter design approach that takes into consideration non-linear interactions among various converter components, source and load. It is shown that with the development of high-temperature, high-power SiC power module technology, magnetic components and capacitors become important technology challenges, and cannot be ignored. A 50% improvement in power density is calculated for a 100 V-2 kV, 7 kW SiC DC-DC power converter operating at 150/spl deg/C compared to a silicon power converter. The SiC power converter can be operated at junction temperatures in excess of 300/spl deg/C (as compared to 150/spl deg/C for a silicon power converter) with reasonable efficiency that potentially leads to a significant reduction in thermal management.