IN Brief:
- The design targets Open Rack V3 installations and emerging high-voltage data centre systems.
- Peak efficiency exceeds 98 per cent at 480VAC input and half load.
- A 20-millisecond energy buffer provides hold-up during short input interruptions.
Infineon Technologies has introduced a 27kW three-phase power supply reference design for high-density AI server applications, using a combination of silicon carbide and silicon switching devices with digitally controlled conversion stages.
The architecture is designed for power supply manufacturers developing equipment around the Open Compute Project Open Rack V3 specification and the growing use of high-voltage direct-current power distribution in AI computing installations.
The reference design accepts a three-phase alternating-current supply and provides a regulated output through a multistage conversion architecture. Its stated AC input range spans 311V to 528V.
Infineon gives peak efficiency above 98 per cent at 480VAC input and 50 per cent of rated output. The stated figure is tied to that test condition and must not be interpreted as efficiency across the entire load range.
Conversion efficiency is important at high power levels because losses turn largely into heat. In dense racks, the thermal design must remove that heat while maintaining acceptable component temperatures and electrical clearances.
The first conversion stage uses a five-level active neutral-point-clamped power factor correction topology. Multiple switching voltage levels affect the electrical stress carried by individual devices and can influence filtering and switching losses.
Multilevel circuits also increase control and component coordination requirements. The practical balance between efficiency, cost and complexity depends on switching frequency, semiconductor performance and the required electrical operating range.
A three-level LLC resonant stage provides further conversion from the intermediate DC link. The resonant network shapes the switching characteristics and supports regulated energy transfer under the control of the power electronics system.
The equipment integrates CoolSiC and CoolMOS power semiconductor devices with EiceDRIVER gate drivers, current sensing and PSOC digital control devices. These elements support switching, feedback and regulation of the converter stages.
Silicon carbide devices can handle demanding switching requirements, but whole-system performance depends on magnetic components, thermal interfaces, circuit configuration and controls as well as semiconductor selection.
The reference design has a stated power density of 116 watts per cubic inch. That specification relates output power to the volume occupied by the conversion equipment, with packaging constraints including insulation, heat removal and connection hardware.
An integrated energy buffer provides approximately 20 milliseconds of hold-up time. The buffer is intended to support regulated output briefly when the incoming supply is disturbed or interrupted.
Hold-up capability is not equivalent to long-duration backup power. Large UPS systems and site-level electrical continuity arrangements provide different services and remain subject to the wider data centre electrical design.
The buffer also addresses the short-term voltage effects of changing GPU electrical loads. Those loads can rise and fall quickly as computing activity changes, creating demands on converter regulation and available stored energy.
Digital control manages the power factor correction and resonant conversion stages. The controller must respond to changing input and output conditions while keeping current, voltage and temperature within the intended limits.
Power factor and input harmonics matter when many high-power supplies share an electrical distribution system. Poor power quality can increase network loading and affect equipment performance, making the behaviour of the input converter significant.
The PSU has an indicated ambient operating range from minus 5°C to 45°C. Actual thermal performance will depend on the way manufacturers package the design and provide airflow or other cooling arrangements.
Infineon plans to demonstrate the reference system during the Open Compute Project Global Summit in October. The design remains an engineering reference for manufacturers rather than a confirmed deployment at a named data centre.
The use of a three-phase supply also affects installation requirements within the data centre electrical distribution architecture. Protective devices, conductor sizing, earthing and power quality must be coordinated with the equipment upstream of the PSU. Reference performance in a laboratory does not replace verification in the completed rack or distribution system.
A PSU manufacturer adapting the reference design may select different mechanical cooling arrangements or operating parameters. Such modifications require retesting of efficiency, thermal behaviour, electromagnetic compatibility and electrical safety. The published reference design establishes a potential circuit architecture rather than a certification for every derivative commercial product.
Infineon’s 27kW design supplies manufacturers with an evaluated electrical architecture, not a claim that every derived power supply will achieve identical figures in service. Performance will depend on the commercial product’s switching, cooling and control arrangements and on testing at the specified electrical input, load and ambient conditions. Its reference efficiency, density and hold-up capabilities therefore require separate qualification in finished equipment.
