Electric vehicles are evolving fast, demanding smarter, more efficient power conversion. This trend increases the complexity of key components like onboard chargers and DC/DC converters. Infineon meets this challenge by using a powerful and flexible microcontroller for the digital control of power converters. Validated with dSPACE HIL systems, this innovation accelerates development and paves the way for faster and more efficient charging solutions.
Electric vehicles rely on a range of power converters to manage energy efficiently. The onboard charger (OBC) converts AC voltage from the grid into DC voltage to charge the high-voltage battery. Meanwhile, the high-voltage to low-voltage (HV-LV) DC/DC converter steps down the high battery voltage to supply the vehicle’s low-voltage loads. As vehicle architectures become more integrated and compact, Infineon’s goal was to combine both applications into a single, intelligent system, reducing complexity while boosting performance and efficiency.
The power flow in electric vehicles: AC voltage from the grid is converted into DC voltage by the onboard charger (OBC) to charge the high-voltage EV battery. An HV-LV DC/DC converter ensures that the vehicle’s low-voltage loads, such as lights, power windows, and windshield wipers, are supplied with the appropriate voltage level.
Trends in OBC Design
OBC development is shaped by some major trends: The systems must support faster charging, higher power density, and even bidirectional energy flow – without increasing hardware complexity. At the same time, the OBCs and HV-LV DC/DC converters must meet stringent safety standards and ensure long-term reliability, while the automotive industry focuses on faster time to market. To address these challenges, the industry is moving towards integrated designs combining several functions in a single system. This approach not only reduces costs and space but also enables the use of a single microcontroller unit (MCU) instead of multiple ones.
The Role of AURIX™ TC4x MCU
In EV charging applications, an MCU is needed to manage various tasks, including:
- The digital control of the power converters
- The communication between the converters and other ECUs, such as the battery management system (BMS)
- Safety monitoring
To combine the OBC and HV-LV DC/DC applications in a single system, Infineon relies on its powerful AURIX™ TC4x microcontroller. With its multicore architecture, high clock speed, and powerful parallel processing unit, it can manage all key functions within a single device. This enables independent CPU usage for real-time critical use cases, eliminating the need for multiple MCUs, software source codes, and tool chains. The result: faster development, lower costs, and a more streamlined system design.
Model-Based Design Approach
To manage the growing complexity in the field of power electronics, Infineon adopted a model-based design (MBD) approach for developing the control system of the power converters. This means that both design and validation take place in a simulated environment. The method allows the developers to design their control algorithms at a high level and test them at an early stage, without having to rely on early hardware prototypes. Since the design is done on an abstract level, no MCU-specific, hand-written code needs to be generated. Especially in highly dynamic applications like OBCs and DC/DC converters, MBD thus helps provide early insights into system behavior, validate safety margins, and evaluate new control strategies.
Challenge: Ultra-Fast Switching Converters
One of the key challenges in developing and controlling automotive power converters is their extremely high switching frequency – often exceeding 100 kHz. To be able to continuously and accurately reproduce this dynamic behavior, highly responsive and precise simulation models are required. For this, Infineon relies on high-performance FPGA-based plant models from dSPACE. For the simulation, the electrical circuit is divided into different stages and each stage is modeled separately: the AC/DC converter stage, also called PFC stage, the HV-HV DC/DC converter stage, and the HV-LV DC/DC converter stage. Each power stage is represented by a customized dSPACE plant model. By combining these models into an overall simulation, the behavior of the controller and the power stages can be optimally reproduced.
HIL Setup for MCU Testing
To evaluate and fine-tune the control of the OBC and the HV-LV DC/DC converter, Infineon created a virtual test setup combining the AURIX™ TC4x MCU with the plant models of the three power converters. The models were implemented on the dSPACE SCALEXIO LabBox, the compact real-time system for hardware-in-the-loop (HIL) testing. The modular dSPACE system is equipped with FPGA boards to emulate the power stages with high precision. Depending on model complexity, multiple stages can be combined on a single FPGA, reducing hardware requirements. The plant models run at a small discrete time step on the FPGAs. To achieve optimum emulation quality, each model operates at a sample rate that is at least 20 to 30 times higher than the converter’s switching frequency. For parameterization, tuning, and visualization, Infineon uses ControlDesk, the dSPACE experiment and instrumentation software for ECU development. This setup enables in-depth analysis of the MCU’s performance when controlling OBC and DC/DC applications.
Infineon uses this HIL setup to test its controller for the OBC and the HV-LV DC/DC converter. The AURIX™ TC4x MCU is tested as the device under test (DUT) using the dSPACE SCALEXIO LabBox as the real-time platform. FPGA-based plant models from dSPACE simulate the behavior of the power converter stages. dSPACE ControlDesk is used for parameterization and visualization.
Reliable Results Without Physical Prototypes
With the dSPACE HIL system, Infineon can test its MCU for high-voltage onboard chargers at signal level, without the need for real power stages or high-voltage components. Critical parameters, such as the high battery voltages of up to 800 V, are part of the simulation, allowing the developers to evaluate the system behavior in a safe yet realistic environment. The virtual setup also enables easy testing of fault scenarios, which can be reproduced at any time without risks to hardware or personnel. This helps detect bugs and failures early, reducing design errors and improving the overall system reliability.
Controlling multiple power converters with a single MCU is a complex task, but thanks to the HIL approach, the OBC developers receive fast and realistic feedback early in the development process. “The HIL system from dSPACE has proven to be a valuable tool in our mission to make life easier, safer, and greener. By leveraging this system, we were able to significantly accelerate the testing of our control software for onboard chargers and DC/DC converters. This not only showcased the capabilities of our AURIX™ TC4x microcontrollers, but also demonstrated the efficiency of model-based design workflows. The scalability and reusability of the HIL system, combined with the reduced need for physical prototypes, have enabled us to focus on developing innovative solutions that meet the evolving needs of the automotive industry. By streamlining our development process, we can bring new technologies to market faster, ultimately making a positive impact on people's lives," concludes Nagendra Badiger, who is responsible for power conversion system architectures at Infineon.
The HIL system from dSPACE has proven to be a valuable tool in our mission to make life easier, safer, and greener. By leveraging this system, we were able to significantly accelerate the testing of our control software for onboard chargers and DC/DC converters.
The scalability and reusability of the HIL system, combined with the reduced need for physical prototypes, have enabled us to focus on developing innovative solutions that meet the evolving needs of the automotive industry.
Conclusion and Outlook
Infineon has shown how model-based design, using scalable HIL test systems and high-precision simulation models, enables accurate and efficient development of complex converter control systems – even in demanding applications involving multiple converters. The collaboration with dSPACE has been key to mastering the complexity and dynamics of modern power electronics. By combining the AURIX™ TC4x MCU with the SCALEXIO HIL platform and FPGA-based simulation models from dSPACE, Infineon can validate its control strategies comprehensively and early, long before physical prototypes are available. Looking ahead, Infineon plans to refine and expand its virtual testing capabilities to continue driving innovation in the fast-moving e-mobility sector.
Courtesy of Infineon Technologies AG
dSPACE MAGAZINE, PUBLISHED AUGUST 2025
The article was created in close cooperation with the following persons:
Nagendra Badiger
Nagendra Badiger is Senior System Application Engineer at Infineon, responsible for power conversion system architectures.
Marko Gecic
Marko Gecic is Principal Application Engineer at Infineon, focusing on automotive microcontrollers for electric drives.
Christian Weber
Christian Weber is responsible for product marketing of the AURIX™ TC4x at Infineon.
Power Stages in EV Charging
- Power converter stages in the OBC:
- AC/DC converter stage, also called PFC stage: This stage rectifies the AC voltage from the power grid into a DC voltage. It also performs the power factor correction (PFC) functionality to improve the power grid voltage quality.
- HV-HV DC/DC converter stage: This stage converts the DC voltage output from the PFC stage into another DC voltage level to feed the high-voltage battery.
- At least one HV-LV DC/DC converter stage: This stage steps down the high-voltage battery power to supply the vehicle’s low-voltage loads fed by a voltage of 12 V or 48 V.
See this white paper published by Infineon for more detailed technical information.
Ready-to-Use Models for Power Electronics Simulation
The dSPACE model library XSG Power Electronics Systems offers preconfigured simulation models of key power electronics circuits, including:
- Bidirectional DC/DC converter (incl. buck & boost)
- Totem-pole PFC in different configurations
- CLLC and CLLLC resonant converters
Optimized for highly dynamic applications with switching frequencies of up to 500 kHz, the parameterizable models enable flexible testing and offer convenient usability.
Learn more: XSG Power Electronics Systems (XSG PES)
