A Novel Multiple DBC-staked units Package to Parallel More Chips for SiC Power Module

Silicon carbide(SiC) power modules play an essential role in the electric vehicle drive system. To improve their performance, reduce their size, and increase production efficiency, this paper proposes a multiple staked direct bonded copper(DBC) unit based power module packaging method to parallel more chips. This method utilizes mutual inductance cancellation effect to reduce parasitic inductance. Because the conduction area in the new package is doubled, the overall area of power module can be reduced. Entire power module is divided into smaller units to enhance manufacture yield, and improve design freedom. This paper provides a detailed design, analysis and fabrication procedure for the proposed package structure. Additionally, this paper offers several feasible solutions for the connection between power terminals and DBC untis. With the structure, 18dies were paralleled for each phase-leg in a econodual size power module. Both simulation and double pulse test results demonstrate that, compared to conventional layouts, the proposed package method has 74.8% smaller parasitic inductance and 34.9% lower footprint.

Investigation on the Novel High-performance Copper/Graphene Composite Conductor for High Power Density Motor

High-performance Cu/Graphene composite wire synergistically strengthened by nano Cr_(3)C_(2) phase was directly synthesized via hot press sintering followed by severe cold plastic deformation, using liquid paraffin and CuCr alloy powder as the raw materials. Since graphene is in situ formed under the catalysis of copper powder during the sintering process, the problem that graphene is easy to agglomerate and difficult to disperse uniformly in the copper matrix has been solved. The nano Cr_(3)C_(2)-particles nailed at the interface favor to improve the interface bonding. The Cu/Graphene composite possesses high electrical conductivity, hardness, and plasticity. The composite wire exhibits high electrical conductivity of 96.93% IACS, great tensile strength of 488MPa, and excellent resistance to softening. Even after annealing at 400℃ for 1 h, the tensile strength can still reach 268 MPa with a conductivity of about 99.14% IACS.The wire's temperature coefficient of resistance(TCR) is largely reduced to 0.0035/℃ due to the complex structure,which leads the wire to present low resistivity at higher temperatures. Such Cu/Graphene composite wire with excellent comprehensive performance has a good application prospect in high-power density motors.

Review of Thermal Design of SiC Power Module for Motor Drive in Electrical Vehicle Application

In the current vehicle electric propulsion systems,the thermal design of power modules heavily relies on empirical knowledge,making it challenging to effectively optimize irregularly arranged Pinfin structures,thereby limiting their performance.This paper aims to review the underlying mechanisms of how irregularly arranged Pinfins influence the thermal characteristics of power modules and introduce collaborative thermal design with DC bus capacitor and motor.Literature considers chip size,placement,coolant flow direction with the goal of reducing thermal resistance of power modules,minimizing chip junction temperature differentials,and optimizing Pinfin layouts.In the first step,algorithms should efficiently generating numerous unique irregular Pinfin layouts to enhance optimization quality.The second step is to efficiently evaluate Pinfin layouts.Simulation accuracy and speed should be ensured to improve computational efficiency.Finally,to improve overall heat dissipation effectiveness,papers establish models for capacitors,motors,to aid collaborative Pinfin optimization.These research outcomes will provide essential support for future developments in high power density motor drive for vehicles.

Message from Editors

THE rapid growth of new energy vehicles is accelerating the low-carbon transition in the global transportation sector. According to the international energy agency report, more than 10 million electric vehicles(EVs) including pure electric and hybrid models were sold worldwide in 2022, which means that the global share of electric vehicles in the overall automotive market has risen from less than 5% in 2020 to 14% in 2022.

Technical Approaches Towards Ultra-High Power Density SiC Inverter in Electric Vehicle Applications

Along with the rapid growth in electric vehicle(EV)market,higher power density and more efficient motor drive inverters are required.It is well known that silicon carbide(SiC)has advantages of high temperature,high efficiency and high switching frequency.It is believed that the appropriate utilization of these merits can pave the way to ultra-high power density inverters.This paper presents issues about SiC chip’s current-carrying capability enhancement which is crucial for a compact inverter of tens and hundreds of kilowatts.Technical approaches towards ultra-high power density EV inverter including SiC module packaging,dc-link capacitor function analysis and system level integration are discussed.Different PWM algorithms which may improve efficiency and help to reduce the inverter volume are also studied.

A Hybrid Si IGBT and SiC MOSFET Module Development

A compact wirebond packaged phase-leg SiC/Si hybrid module was designed,developed,and tested.Details of the layout and gate drive designs are described.The IC chip for gate drive is carefully selected and compared.Dual pulse test confirmed that,the switching loss of hybrid module is close to pure SiC MOSFET module,and it is much less than pure Si IGBT device.The cost of hybrid module is closer to Si IGBT.

An Improved Planar Module Automatic Layout Method for Large Number of Dies

The layout of power modules is one of the key points in power module design,especially for silicon carbide module,which may parallel more devices compared with silicon counterpart.In this paper,along with the design example,a improved layout design method for planar power modules is presented.Some practical considerations and implementations are also introduced in the optimization of module layout design.

Online Monitoring Method for Junction Temperature of SiC MOSFETs based on Temperature Sensitive Electrical Parameter

Compared to Si devices,the junction temperature of SiC devices is more critical due to the reliability concern introduced by immature packaging technology applied to new material.This paper proposes a practical SiC MOSFET junction temperature monitoring method based on the on-state voltage$\\boldsymbol{V}_{\\mathbf{ds}(\\mathbf{on})}$measurement.In Section II of the paper,the temperature sensitivity of the on-state voltage$\\boldsymbol{V}_{\\mathbf{ds}(\\mathbf{on})}$is characterized.The hardware of the measurement system is set up in Section III,which consists of an On-state Voltage Measurement Circuit(OVMC),the sampling and isolation circuit.Next,a calibration method based on the self-heating of the SiC MOSFET chip is presented in Section IV.In the final Section,the junction temperature is monitored synchronously according to the calibration results.The proposed method is applied to a Buck converter and verified by both an Infrared Radiation(IR)camera and a Finite Element Analysis(FEA)tool.

Review of Hybrid Packaging Methods for Power Modules

The hybrid structure of a power-module package is summarized and classified.Basic and extended planar wire-bond designs are analyzed and compared with regular wire-bond modules and planar modules,respectively.The automatic layout method can improve the electrical and thermal performance of hybrid structures.A state-of-the-art hybrid structure is introduced,and suggestions for alleviating the current and temperature imbalances for future designs are provided.

Review of Si IGBT and SiC MOSFET Based on Hybrid Switch

SiC Hybrid switch(HyS)combines low conduction loss of Si IGBT and low switching loss of SiC MOSFET,and the cost is closer to that of Si IGBT.The promising high performances of HyS will bring considerable achievement in terms of enhancing power density of a converter system.By reviewing the gate drive pattern,gate drive hardware,current sharing,module design,converter design,and cost,this paper introduces state-of-the-art SiC HyS.

Review of Power Module Automatic Layout Optimization Methods in Electric Vehicle Applications

The layout of power modules is a crucial design consideration,especially for silicon carbide devices.For electrical layout,optimizing the parasitic parameters can improving switching loss and dynamic behavior.For thermal layout,reducing the thermal resistance and controlling thermal capacitance can reduce the local hot point.Conventional layout design iterations are based on human knowledge and experience.But the major drawback of manual design methods is a limited choice of candidates,large time consumption and also the lack of consistency.With the introduce of automatic layout design,these challenges can be overcome which in the meanwhile alleviates current and temperature imbalance.By reviewing element representation,placement,routing,fitness evaluation,and the optimization algorithm approaches,a state-of-the-art power module layout design method for electric vehicle applications is introduced.

Monitoring of SiC MOSFET Junction Temperature with On-state Voltage at High Currents

A junction temperature monitoring method has been presented based on the on-state voltage at high currents.With a simplified physical model,this method mapped the relationship between junction temperature and on-state voltage.The tough calibration and signal sensing issues are solved.Verified by body-diode voltage detecting method,the presented method shows a good performance and high accuracy,in the meantime,it would not change the modulation strategy and topology of the converter.

Accurate Evaluation of Cooling System Capability of Three-phase IGBT-based Inverter

In this paper,an offline evaluation method for the cooling capability of three-phase insulated-gate bipolar transistor(IGBT)inverters is presented,which can better emulate real working conditions.With a properly designed sudden-stop control sequence,the conventional junction temperature monitoring method at a low current is used to calculate the junction temperature before the sudden stop of an inverter.This can solve the challenging switching loss calculation issue in conventional methods.Finally,the feasibility,control sequence,and electrical behaviors of the proposed method are validated through experimental tests.

Online Junction Temperature Measurement of Double-sided Cooling IGBT Power Module through On-state Voltage with High Current

The aim of this study is to achieve online monitoring of the junction temperature of double-sided-cooling insulated gate bipolar transistor(IGBT)power modules by using the on-state voltage under a high current to maximize the utilization of IGBT power chips.Online junction temperature measurement plays an important role in improving the reliability of the inverter with IGBT,increasing the power density of the motor controller of electric vehicles,and reducing the cost of electric vehicles.

Modular Design Method for Motor Drives

This paper introduces the concept of modular design methodology for hardware design and development of motor drives.The modular design process is first introduced separating the hardware development into three parts:controller,mother board and phase-leg module.The control and circuit function can be decoupled from the phase-leg module development.The hardware update can be simplified with the phase-leg module development and verification.Two design examples are used to demonstrate this method:a DC-fed motor drive with Si IGBTs and an AC-fed motor drive with SiC devices.Design of DC-fed motor drive aims at developing the converter with customized IGBT package for high temperature.Experience with development of the converter with commercial IGBTs simplifies the process.As the AC-fed motor drive is a more complex topology using more advanced devices,the modular design method can simplify and improve the development especially for new packaged devices.Also,the modular design method can help to study the electromagnetic interference(EMI)issue for motor drives,which is presented with an extra design example.

A Finite Difference Method Modeling for IGBT and Diode in PSPICE

In this paper,a novel modeling approach for both PiN diode and IGBT is presented.In this model,the carrier diffusion equation,which retains the distributed nature of charge dynamics in bipolar power devices,is solved directly by finite difference method in PSPICE.The physical basis of this model and some practical considerations are introduced.Compared with conventional Fourier based IGBT model,the presented model keeps higher simulation speed and comparable high accuracy.These features were also verified by simulations and experiments.