An Innovative HIL Test Bench to Validate Embedded SOCOMEC Inverter Software

The Company

SOCOMEC is an international industrial group represented across five continents, specializing in electrical equipment for the service and industrial sectors. As a leader in switching and protection, energy efficiency, and power converters—such as Uninterruptible Power Supplies (UPS)—SOCOMEC focuses on continuous innovation to ensure high availability, safety, and energy performance for critical power infrastructure.

The Challenges

• Strict Real-Time Constraints: Validating embedded software for power electronic converters operating at chopping frequencies exceeding 10 kHz required ultra-fast real-time simulation models running at over 200 kHz (up to 1 MHz for converter models).
• High Circuit Complexity: The HIL simulator needed to support over 150 simulation variables, 50+ semiconductors, 36 PWM control inputs, and 30 real-time analog output signals concurrently.
• Long Recompilation Bottlenecks: Traditional FPGA-based simulation tools required lengthy FPGA compilation processes whenever changes were made to converter circuit schematics.
• Diverse Power Grid Waveforms: Testing product reliability against extreme environmental conditions and global grid voltage/frequency disturbances that cannot be safely or easily replicated on physical test benches.

The OPAL-RT Solution

SOCOMEC deployed an integrated NI and OPAL-RT hardware and software HIL solution:

• OPAL-RT eHS Solver on FlexRIO FPGA: Implemented the eHS64 real-time solver on an NI FlexRIO FPGA board within an NI PXI Express chassis, enabling instant schematic changes without FPGA recompilation.
• Unified VeriStand & LabVIEW Environment: Utilized NI VeriStand to manage real-time I/O, acquire signals, and run LabVIEW environment models for lower real-time constraint components like batteries and motors (< 5 kHz).
• Automated Test Sequences via TestStand: Partnered with MESULOG to design business-driven TestStand modules and automated test sequences for non-regression and fault-injection testing on Unit Under Test (UUT) boards.
• High-Fidelity Converter Simulation: Simulated fast-switching power converters and related filters at microsecond/sub-microsecond time steps (< 1 MHz solver execution).

The Results

• Sub-Minute Model Reconfiguration: Achieved the ability to modify digital power electronics circuit schematics and see simulation results in less than a minute, eliminating hours of FPGA compilation.
• Rapid System Deployment: System engineers from NI, OPAL-RT, and MESULOG brought the HIL test bench to full operation in less than a week.
• De-Risked Software Validation: Provided developers with a risk-free platform to test complex features, inject fault modes, and replay error sequences safely.
• Expanded Global Grid Reliability: Enabled rigorous testing under extreme temperatures and global grid voltage/frequency degradation that physical test benches could not replicate.
• Improved Quality & Reduced Time-to-Market: Standardized automated non-regression testing, dramatically accelerating product development cycles while raising product reliability.

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