The Task
Resonant converters are a widely used topology for DC/DC converters. They offer a very high energy density and excellent efficiency across a wide operating range. Thanks to these superior properties, resonant converters are often used in onboard chargers of electric vehicles.
The size and weight of components are of crucial importance in today’s world, especially when it comes to mobile applications, for example, in the automotive industry. In this context, one thing is important to know: The higher the switching frequency of the resonant converter, the smaller the inductances and transformers become. For this reason, high frequencies are undoubtedly the perfect choice for mobile applications. Depending on the power and application of the resonant converters, their switching frequency nowadays ranges from around 100 kHz up to several MHz.
Wide-bandgap (WBG) semiconductors, such as silicon carbide (SiC) and gallium nitride (GaN), can operate at considerably higher switching frequencies compared to silicon (Si)-based semiconductors – at similar losses. In fact, they can handle switching frequencies that are about 10 times higher. Thanks to this property, switching frequencies above around 100 kHz are the typical domain for WBG semiconductors in automotive applications. The switching frequencies in these applications usually range up to 500 kHz, and the trend is moving towards even higher frequencies.
The Challenges
Hardware-in-the-loop (HIL) simulation of power electronics circuits is a widely used method for testing the controls of resonant converters. The aim is to test and validate the controls at the signal level while simulating the entire power electronics on a HIL system.
However, the models used for the simulation have an inherent limit for the switching frequency that they can simulate. This limit is a result of different factors, including the computing performance of the algorithms.
The drastic increase in the switching frequency therefore requires a higher performance of the algorithms used. Unfortunately, existing models and tools are hardly able to deliver the required computing performance.
The dSPACE Solution
Simulation models that are specifically designed to run at high switching frequencies are the key to success. Our XSG Power Electronics Systems (PES) solution is such a specialized tool. The powerful dSPACE software provides a library containing ready-to-use simulation models of common power electronics circuits and is the ideal choice for developing and testing highly dynamic electrical systems. Although it is a library, the included models are customizable in terms of the component ratings, type of switching elements, and the interface configuration.
And best of all: XSG PES is able to simulate CLLC resonant converters at high switching frequencies of up to 500 kHz, making it the perfect choice for testing fast-switching resonant converters.
Our XSG PES solution creates the required FPGA model of your circuit. After integrating this model into your existing FPGA framework, you can configure and generate the FPGA build using the dSPACE FPGA Programming Blockset, the Simulink® blockset for using an FPGA model created with a dSPACE system. Finally, you can upload the FPGA build to your SCALEXIO hardware-in-the-loop (HIL) system to run your simulation and tests and keep track of the results.
