External Primary Control in Power Electronics Applications

The company

GEISER is a power electronics research group at the University of Alcalá (Universidad de Alcalá), a public university located 25 km from Madrid, Spain. Recognized as one of the most relevant power electronics laboratories in Europe, GEISER has developed more than a dozen power converter systems, demonstrating deep expertise in energy conversion and control.

Velox-PS, a young company in the energy sector uniting over 15 years of experience in converter and control system design, sponsors this project—proving the strong commercial interest in externalized primary control for industrial applications.

The Challenges

• Control Speed Constraints: Primary control must act extremely fast (sub-millisecond), making externalization outside the converter hardware technically demanding.
• Electromagnetic Interference: Power electronics systems generate significant electromagnetic interference, requiring communication channels that are immune to noise and maintain galvanic isolation.
• Inflexible Control Updates: Traditional approaches embed primary control locally inside converters—any algorithm change requires reprogramming the power equipment, slowing research and development.
• Multi-Device Coordination: Managing multiple converters independently creates resource redundancy; centralizing control on a single platform requires deterministic, low-latency communication across all devices.

The OPAL-RT Solution

The team built an external primary control system combining OPAL-RT’s real-time computing power with high-speed optical communication:

• Real-Time Simulator: The OP5707XG from OPAL-RT serves as the external controller, running both primary and secondary control algorithms implemented directly from MATLAB/Simulink models via automatic code generation.
• High-Speed SFP Communication: Up to 5 Gbit communication via 16 SFP optical fiber channels connects the converter to the simulator—ensuring electromagnetic immunity, galvanic isolation, and long-distance capability.
• Converter Interface Modules: A custom three-module converter control system handles ADC acquisition (voltage/current measurements), SFP data packaging and transmission, and PWM signal generation for IGBT switching.
• Ultra-Low Latency: The entire control loop—from sensor acquisition through external computation to PWM output—operates within control periods of approximately 100 µs.

The results

The project successfully demonstrated externalized primary control as a viable paradigm for power electronics:

• Proven Concept: Demonstrated that primary control can be reliably executed outside the converter on an external real-time simulator without compromising performance.
• Rapid Algorithm Prototyping: Novel control algorithms are deployed instantly via MATLAB/Simulink without reprogramming the physical power equipment—dramatically accelerating R&D iteration.
• Centralized Multi-Device Control: A single OPAL-RT platform manages primary control for multiple converters, reducing hardware redundancy and simplifying system architecture.
• Industry Validation: Velox-PS sponsorship confirms commercial viability, with applications spanning customized testing laboratories, high-power supplies, power quality stations, and traction solutions.

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