Products UsedANSYS® Simplorer®

KeywordsPower electronics, IGBT, MOSFET, diode, switch, surge, EMC (EMI), characterization

Device Characterization ToolANSYS Simplorer provides a system-level library for IGBTs, MOSFETs and diodes for quick evaluation of circuit behavior and control algorithms. As the design evolves, developers need a more-detailed version of these devices. Simplorer’s device characterization tool enables users to incorporate device information — such as working point, breakdown, test confi guration, transfer and output characteristics, thermal impedance, switching energy, etc. — to accurately characterize the devices for simulation. For IGBTs, the device characterization tool provides three levels of modeling (Figure 1):• Average model: Provides basic operation and is optimized for electrother-

mal evaluation. (Power injection into thermal network can be averaged to speed up simulation.) This level is valid for evaluation of the long thermal time constant aspects (compared to fast-switching electrical time constants) of the switching device. You should not use this level for the design of gate drives or EMI, as the switching characteristics require additional detailed modeling.

• Basic dynamic model: Adds additional transient (dynamic) behavior and default voltage dependent capacitance, which yield more-accurate gate drive response, as well as switching characteristics. This level is suitable for evaluating circuit-level switching behavior and associated transients.

• Advanced dynamic model: Adds additional parameter access, user-defi ned voltage dependent capacitance, more-detailed and accurate overshoot, tail current, and gate drive characteristics. This level is ap-propriate for the most-accurate gate drive design, detailed EMI/EMC and switching transient analysis.

Application Brief

ANSYS Simplorer Device Characterization Tools

ANSYS® Simplorer® simulates circuits and systems for a wide variety of applications. It has the capability to model at diff erent levels of abstraction, providing optimal simulations for diff erent phases of the design process. As part of this capability, Simplorer supports device and system component characterization tools for IGBT, MOSFET and diode model generation. ANSYS devel-oped the tools in collaboration with industry-leading experts to provide the diff erent levels of abstraction, which aid in designing power electronic systems. Simplorer links with other ANSYS software to provide additional detailed thermal and electrical parasitic modeling for these devices. Simplorer also supports importing VHDL-AMS, C and SPICE models.

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Figure 1. Diff erent levels of IGBT modeling available with Sim-plorer’s device characterization tool

ANSYS Simplorer Device Characterization Tools

Automatic Parameter FittingSimplorer’s device characterization tool includes a sheet scan utility. This imports characteristics from data sheets and automatically creates required model parameters for each device level. The user interface enables you to select the type of device (IGBT, Power-MOSFET or power-diode) to be cre-ated, then scans information from the manufacturer data sheet (Figure 2).

Figure 2. IGBT device characterization fl ow using sheet scan utility

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Thermal Parameter FittingThe device characterization tool also provides thermal modeling for each device. You can apply this characteristic to the model in several ways. Data sheets often provide thermal curves or thermal resistance and capacitance equivalents to represent thermal impedance (Figure 3); Simplorer’s device characterization tool can import either of these. Alternatively, the thermal network can be created external to the device, a process useful in creating a more-detailed thermal network. This can be based on Simplorer’s thermal library or imported detailed thermal models from other ANSYS thermal tools.

Figure 3. Thermal characteristics for device models

ANSYS Simplorer Device Characterization Tools

Figure 4. Importing detailed thermal model for IGBT package from ANSYS Icepak into ANSYS Simplorer

Figure 5. Three-phase inverter utilizing IGBT model in conjunction with package parasitic created from Q3D Extractor

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Application ExamplesFigure 4 shows an example of an inverter motor drive using an IGBT multi-package (several IGBTs in one package). The IGBT electrical characteristics were created in the device characterization tool. To optimize the design, it is important to understand the detailed thermal characteristic of the IGBT multi-package. In this case, ANSYS Icepak was used to model the thermal package and import that model into Simplorer. The detailed IGBT thermal model then interacts with the IGBT electrical model in the system.

Figure 5 shows an inverter circuit using IGBTs in Simplorer. In this case, the IGBT package electrical parasitic (lead inductance) was modeled using ANSYS Q3D Extractor coupled into Simplorer to interact with the IGBT mod-el in the system. Q3D Extractor also modeled the bus bar and other cabling in the system. The motor model was created in ANSYS Maxwell and brought into Simplorer. This detailed modeling approach enables high-fi delity conducted noise analysis of common mode and diff erential mode currents.

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ANSYS Simplorer Device Characterization Tools

SummaryDepending on the phase of the design process, diff erent levels of model abstractions can be used to increase simulation effi ciency. At the system level, you can use a combination of detailed and higher-level component models. This enables detailed analysis of specifi c blocks of the system as well as modeling other blocks at a higher level to speed up simulation. Simplorer’s capability to provide diff erent levels of component models, along with the ability to link with other ANYSS tools for additional detailed thermal and electrical parasitic modeling, yield a unique top-down or bottom-up design process capability, depending on your simulation needs.