Infineon 27 kW Three-Phase PSU for AI Servers: Topology, Efficiency and Design

Introduction: Why AI Servers Need a New Generation of Power Supplies

Artificial intelligence is changing the way data centers are designed. Modern AI servers contain powerful GPUs, accelerators and high-performance processors that consume substantial amounts of electrical power. As data center operators increase the number of accelerators installed in each rack, the power supply must deliver more energy within a limited physical space.

This creates several engineering challenges. The power supply must achieve high efficiency, handle rapid load changes, minimize heat generation and maintain reliable operation under demanding conditions. At the same time, the power architecture must be scalable enough to support increasingly high rack power levels.

To address these requirements, Infineon Technologies announced a 27 kW three-phase power supply unit (PSU) reference design on October 8, 2026. The solution is intended for server original equipment manufacturers (OEMs), original design manufacturers (ODMs) and next-generation AI data center power architectures.

The reference design is aligned with the Open Compute Project (OCP) Open Rack V3 (ORV3) specification. It combines Infineon's CoolSiC and CoolMOS power MOSFETs, EiceDRIVER gate drivers, XENSIV current sensors and PSOC microcontrollers.

Its major features include a five-level active-neutral-point-clamped power-factor-correction stage, a three-level LLC converter, an integrated energy buffer and digitally controlled power conversion.

According to Infineon, the design achieves peak efficiency above 98% at 480 V AC input and 50% load, with a power density of 116 W/in³. It also provides 20 ms of hold-up time during short power-grid disturbances. Official announcement: Infineon Technologies.

Key Specifications of the 27 kW PSU

The following table summarizes the principal specifications announced by Infineon.

Parameter	Specification
Manufacturer	Infineon Technologies
Application	AI servers and high-density data center racks
Rated power	27 kW
Input	Three-phase AC
Published input-voltage range	311–528 V AC
Peak efficiency	More than 98%
Efficiency test point	480 V AC input, 50% load
Power density	116 W/in³
OCP compatibility	Designed to meet ORV3 requirements
PFC topology	Five-level ANPC
DC-DC topology	Three-level LLC
Main power semiconductors	650 V CoolSiC and CoolMOS MOSFETs
Gate drivers	EiceDRIVER family
Current sensing	XENSIV family
Digital controller	PSOC Control C3 Performance Line
Energy buffering	Integrated
Hold-up time	20 ms
Power-factor performance	Above 0.99 across most of the load range
Input-current distortion	Low input-current total harmonic distortion
Ambient operating temperature	−5°C to +45°C

These are manufacturer-reported specifications. The efficiency figure applies to the stated test point and should not be interpreted as a guarantee of greater than 98% efficiency at every input voltage and load condition.

Why Are Three-Phase Power Supplies Becoming Important?

Conventional server power supplies often use single-phase AC input. This arrangement works well for many computing systems, but it becomes increasingly challenging when each rack requires tens or hundreds of kilowatts.

Three-phase power distribution is widely used in industrial facilities and large electrical installations because it can transfer substantial power with a relatively balanced use of conductors and electrical infrastructure.

For high-power data center systems, three-phase input can provide several benefits:

• Higher power handling: Suitable for power supplies rated at tens of kilowatts.
• Improved integration: Supports compact power conversion for high-density server racks.
• Balanced grid loading: A properly designed three-phase front end can distribute input current more evenly among the phases.
• Scalability: Supports the transition to higher-power rack architectures.
• Potentially lower infrastructure complexity per unit of power: Depending on the facility and distribution design.

However, a three-phase input does not automatically guarantee high efficiency or low harmonic distortion. These properties depend on the rectifier topology, power-factor-correction control, switching devices, filters and the operating point.

Infineon's design addresses these issues through a multilevel PFC stage and digital control.

Understanding the Five-Level ANPC PFC Stage

One of the most important features of this PSU is its five-level active-neutral-point-clamped (ANPC) power-factor-correction topology.

The PFC stage processes the incoming AC power and establishes the DC power needed by the downstream converter. It also shapes the input current so that it follows the input-voltage waveform more closely, helping improve power factor and reduce current harmonics.

What does a multilevel converter do?

A conventional two-level switching leg produces two principal switching-node voltage levels. A multilevel converter can generate more voltage levels, allowing the voltage transitions to be distributed among switching devices.

This can provide advantages such as:

• Lower voltage steps at switching nodes.
• Reduced voltage stress on individual devices, depending on the circuit arrangement.
• Opportunities to reduce filter requirements.
• Improved waveform quality.
• Potentially lower switching losses or electromagnetic interference when the topology and modulation are appropriately optimized.

The actual benefits depend on the switching pattern, component selection and operating conditions.

Why use ANPC?

An active-neutral-point-clamped topology uses actively controlled semiconductor devices to manage current paths and voltage levels around the DC-link neutral point.

Compared with some simpler multilevel arrangements, ANPC designs offer flexibility in controlling switching states and distributing losses between semiconductor devices. This can be useful in high-power converters where efficiency and thermal management are critical.

In a three-phase PSU, the PFC stage must also regulate the DC bus while drawing suitable currents from all three input phases.