NI's Deputy Director Jeong Jae-hyung

The core of electric vehicle (EV) technology goes beyond just the battery and motor. The power converters that connect these two elements—the inverter, onboard charger (OBC), DC-DC converter, and integrated charge/conversion unit (ICCU)—act like a neural network that determines the vehicle's performance, efficiency, and safety. Recent advancements in power devices, system integration, and the proliferation of high-voltage platforms have exponentially increased the complexity of these controllers, necessitating innovation in verification methods.

To address this challenge, NI, a global test and measurement company, has unveiled a next-generation verification strategy centered on FPGA-based signal-level HIL (sHIL). In an interview, NI Vice President Jaehyung Jeong presented a comprehensive approach encompassing everything from inverters to ICCUs, emphasizing that FPGA-based sHIL will become the new standard for EV controllers.

Transforming Power Converter Complexity and Verification

In the past, internal combustion engine controllers were limited to handling physical objects like gearboxes and fuel injection. However, the situation is completely different in electric vehicles. The ECU is no longer simply a control logic unit, but rather acts as a 'brain' that controls the entire high-voltage, high-power circuit in real time.

In particular, the market is currently moving toward ICCU (X-in-1 architecture), which combines the inverter, OBC, and DC-DC into a single controller. While this offers the advantages of reduced wiring, space savings, and improved efficiency, it places the burden of performing much more complex calculations simultaneously on the ECU. Furthermore, the emergence of next-generation power devices such as SiC (silicon carbide) and GaN (gallium nitride) has increased switching speeds, necessitating simulation and verification environments that are significantly faster and more precise than before.

Step-by-step HIL – from virtual to real

NI's strategy aligns with the V-cycle development process: a step-by-step verification process that "increases the scope of the virtual and expands the real."

1. Signal-level HIL (sHIL)

The ECU (controller) is left as actual hardware, while the battery, power circuit, and motor are virtualized as FPGA-based models. It can safely perform risk tests such as algorithms, communication, and fault injection.

2. Power-level HIL (pHIL)

Applying actual high-voltage power, the battery cycler and motor emulator are utilized. Stability is verified under real-world conditions, including power loss, protection logic, and thermal behavior.

3. e-Dyno (test cell)

By connecting actual motors and batteries, verification is performed at a level similar to the final vehicle environment. This allows for efficient use of models and scenarios from previous stages.

"Actual testing begins with only the ECU physically present, while the rest is virtualized, gradually expanding the real-world component. Today, we're focusing on signal-level HIL, where only the ECU is physically present, with the rest being simulated through FPGAs." - NI Vice President Jeong Jae-hyung

FPGAs – A Game Changer for EV Verification

The reason FPGAs are attracting attention for power circuit verification lies in their fundamental differences in computational methods. CPUs convert data into 0s and 1s, store them in memory, and then perform computations. No matter how fast their performance, data input/output delays are unavoidable. On the other hand, FPGAs receive signals as they are and perform parallel operations in logic gate units.

For example, NI's latest PXIe-7891 module supports 400 kHz PWM, 2.5 ns signal capture, and can model four inverters and motors simultaneously, enabling ultra-high-speed power circuit simulations that were previously impossible.

The station manager explained this difference as follows:

FPGAs don't necessarily convert data into 0s and 1s and store it in memory. Instead, they perform calculations by multiplying and adding the signal states as they are. This allows them to simulate power circuits much faster and more accurately, and they can even load complex models, including automotive powertrains, all at once.

ICCU Verification – New Challenges Created by Integration

However, the emerging power converter ICCU (X-in-1 architecture) presents challenges as significant as the benefits of integration. While previously controlling only the OBC or LDC was sufficient, now a single ECU must manage both simultaneously. This presents various risks, including control algorithm conflicts, priority settings, and load distribution.

For this reason, the verification system also requires faster and greater computational power. FPGA-based sHIL can reproduce these complex interactions in real time, and is emerging as an essential verification tool for ICCU development.

Comparison with global competitors

The EVPC verification market has long been dominated by German and Japanese companies. Current major competitors include dSPACE (Germany), OPAL-RT (Canada), ETAS (Germany), and A&D (Japan).

• dSPACE

A traditional powerhouse. It boasts excellent MATLAB/Simulink-based software model compatibility and a wealth of OEM references. However, it is considered a latecomer in FPGA-based power circuit simulation. While a "stable choice," some point out its limitations in EVPC high-speed verification.

• OPAL-RT

The company excels at real-time power electronics simulation using FPGAs. It has a strong presence in research institutions and the aviation and power grid sectors. However, its experience with Tier-1 and OEM collaborations is limited due to a lack of automotive ECU-friendly architecture and interface support. In the EV field, we are cooperating and competing with NI.

• ETAS

Once a Bosch subsidiary and a strong player in the HIL market, the company has now scaled back its HIL business, focusing on calibration and diagnostic tools. The company has transformed from a former powerhouse into a niche player.

• A&D (Japan)

As a HIL company specializing in OEMs in Japan, we provide solutions tailored to local customers. However, we face limitations in global market scalability and in addressing the complexities of EVPCs.

NI's differentiating factors include over 20 years of FPGA experience, comprehensive support for automotive interfaces, turnkey partnerships, and a proven track record of successful Japanese OEM projects. In essence, NI possesses a competitive advantage by embracing the reliability of dSPACE and the pure performance of OPAL-RT while also securing specialized capabilities for the automotive industry.

What's interesting is that NI's HIL platform isn't limited to EVs. It can be expanded to a variety of applications, including electric ships, fuel cell trains, and charging infrastructure verification. This demonstrates that NI is not just a vendor, but a platform company.

EV controllers must simultaneously address three challenges: speed, integration, and safety. FPGA-based sHIL is a powerful tool to address this challenge and is at the core of next-generation verification platforms.

Vice President Jeong Jae-hyung concluded the interview by saying:

"EV controllers are becoming increasingly complex. FPGA-based sHIL is the first tool to address these challenges and will become the standard for verification platforms encompassing inverters, OBCs, DC-DCs, and ICCUs."

Amid intensifying global competition, NI's strategy is more than a simple technology proposal; it's a declaration of a paradigm shift in EVPC verification. As the EV market expands, the speed and scope of this new paradigm are expected to emerge as key variables determining industry competitiveness.