The profile of a power simulation tool for SiC devices

Power electronics design is a critical aspect of modern engineering, influencing the efficiency, reliability, and performance of numerous applications. Developing circuits that meet stringent requirements while considering manufacturing variations and worst-case scenarios demands precision and sophisticated tools.

At the same time, the landscape of power electronics design is rapidly evolving, ushering in an era of high-speed, high-efficiency components. Amidst this evolution, simulation tools need to redefine the way engineers conceptualize, design, and validate power systems. Take Elite Power Simulator and Self-Service PLECS Model Generator (SSPMG), which allows power electronics engineers to reduce time-to-market. Collectively, these tools offer a precise depiction of the operational behavior of the circuit when using EliteSiC line of silicon carbide (SiC) products.

Figure 1 Elite Power Simulator and Self-Service PLECS Model Generator provides a precise depiction of the operational behavior of power circuits. Source: onsemi

This simulation platform aims to empower engineers to visualize, simulate, and refine complex power electronic topologies with unparalleled ease. It does that by offering engineers a unique digital environment to test and refine their designs. Here, the underlying PLECS models and their accuracy are a critical component to the effectiveness of the Elite Power Simulator. The simulator allows engineers to upload custom PLECS models that are generated with the SSPMG.

The heart of this simulation tool is its ability to accurately simulate a wide array of power electronic topologies, including AC-DC, DC-DC, and DC-AC converters, among others. With over 40 topologies available, it provides engineers with an extensive library to explore and fine-tune their designs. For instance, in industrial applications, it supports critical systems such as fast DC charging, uninterruptible power supplies (UPS), energy storage systems (ESS), and solar inverters. Similarly, the tool is suited for onboard chargers (OBC) and traction inverter systems serving the automotive industry.

Figure 2 Engineers can select application and topology in Elite Simulator. Source: onsemi

Challenges in creating PLECS models

The traditional method of creating PLECS models in the industry relies on measurement-based loss tables aligned with manufacturer datasheets. However, this approach faces several key challenges:

Dependency on measurement setups: The switching energy loss data is influenced by the specific parasitics of the application layouts and circuits used, leading to variations and inaccuracies.
Limited data density: Conduction and switching energy loss data are often insufficiently dense, hindering accurate interpolation within PLECS and often necessitating extrapolation, which can compromise accuracy.
Nominal semiconductor conditions: Loss data typically represents nominal semiconductor process conditions, potentially overlooking variations and real-world scenarios.
Validity for hard switching only: Models derived from datasheet’s double-pulse-generated loss data are applicable only to hard switching topologies. They become highly inaccurate when applied to soft switching topology or for synchronous rectification simulations.

These challenges associated with the conventional approach of depending on measurement-based loss tables for PLECS model generation are addressed by introducing the SSPMG. It optimizes models by considering specific passive elements’ impact on energy losses, providing denser and more detailed data for accurate simulations.

Figure 3 Dense loss table is one of the key SSPMG features. Source: onsemi

SSPMG includes semiconductor process variations for realistic models and creates adaptable models suited for soft switching topologies, ensuring reliability beyond hard switching scenarios. PLECS models designed with SSPMG can be seamlessly uploaded to the Elite Power Simulator or downloaded for use in stand-alone PLECS.

Figure 4 Soft switching simulation is another key SSPMG feature. Source: onsemi

Simulator capabilities

Central to the tool’s prowess is PLECS operating in the background. PLECS is a system-level simulator that makes it easier to model and simulate whole systems by using device models that are designed for speed and accuracy. It combines an easy-to-use web-based environment, simplifying things for engineers during the design process.

The significance of this tool extends beyond its simulation capabilities. It’s not merely a tool for simulating; it can also aid engineers in selecting suitable components for their applications. Engineers can seamlessly navigate through various product generations to understand performance-cost trade-offs and make informed decisions.

Moreover, PLECS is not a SPICE-based circuit simulator, where the focus is on low-level behavior of circuit components. The PLECS models, referred to as “thermal models”, are composed of lookup tables for conduction and switching losses, along with a thermal chain in the form of a Cauer or Foster equivalent network.

The simulator has an intuitive loss and thermal data plotting utility that enables engineers to visualize the loss behavior of their chosen switch. This multifunctional 3D visualization tool works with device conduction loss, switching energy loss, and thermal impedance.

Next, the simulator has a utility to design custom heat sink models, enabling users to accurately predict junction temperatures and optimize cooling solutions tailored to their specific needs.

The simulation stage within this tool is highly detailed, offering insights into various parameters such as losses, efficiency, and junction temperature in transient and steady state conditions. Furthermore, the tool has an easy mechanism to compare runs with different devices, circuit parameters, cooling designs, and loss models.

Figure 5 Loss plotting is another important feature offered by Elite Power Simulator. Source: onsemi

The simulator and SSPMG are adaptable to diverse semiconductor technologies. While initially focusing on SiC products, both tools will be expanding to other power devices. This versatility ensures that engineers can leverage the tools across various devices, tailoring simulations to their specific requirements.

Simulating beyond datasheet conditions

The utilization of simulation tools in virtual prototyping has brought about substantial transformation in design flows. Engineers and designers are now able to comprehend the performance of these electronic circuits prior to their mass production in their quest for first time right performance. Accuracy is a critical component when it comes to simulating intricate electronic circuits.

Simulating beyond datasheet conditions is key due to the access to unlimited data that normally would be difficult to acquire via physical testing. This facilitates the optimization and analysis of circuit performance virtually.

By employing precise simulations, one can prevent the underestimation or overestimation of system performances.

James Victory is a fellow for TD modeling and simulation solutions at onsemi’s Power Solutions Group.

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The profile of a power simulation tool for SiC devices

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