3.3kV SiC Drives Medium-Voltage Power Supply Revolution: The Evolution of Busbar from "Conductive Component" to "Core System Component"

As power consumption of AI clusters surges from megawatt to gigawatt levels, the traditional power supply chain of "10kV grid → power frequency transformer → 380V power distribution → 800V rack busbar" faces severe bottlenecks including excessive copper loss, large footprint and difficult capacity expansion. On May 21, 2026, Wolfspeed unveiled two types of 3.3kV SiC power modules at the APEC Exhibition (per official press release), officially kicking off the medium-voltage transformation of AI power supply architectures. This is far more than a simple upgrade of device voltage rating; it represents a complete restructuring of the design logic for the entire power electronic system.In this transformation, high conductivity busbar technology has become increasingly important for improving current transmission efficiency and reducing power losses in next-generation power systems.

Amid this transformation, the busbar, long regarded merely as a conductive connector, has quietly become a core determinant of the practical deployment of medium-voltage SiC systems. A&J Link Technologies specializes in the R&D, design, production and manufacturing of high-performance laminated busbars. Boasting robust R&D and precision manufacturing capabilities, we focus on high-voltage low-inductance busbar technology. For 3.3kV medium-voltage SiC power supply applications in AI data centers, we deliver integrated professional high-performance busbar solutions featuring superior insulation, low parasitic parameters, balanced current sharing and optimized EMI control, laying a solid hardware foundation for stable and efficient operation of medium-voltage power supply systems.

I. Medium-Voltage Transformation of AI Power Supply: Fundamental Restructuring of Busbar Functions

The two 3.3kV SiC modules launched by Wolfspeed precisely cover two core application scenarios for medium-voltage AI power supply architectures:

• HAB900C33LM4 half-bridge module with substrate: Rated 3300V/900A with stray inductance <10nH. Adopting copper substrate and sintered chip technology, it targets high-power-density main switching applications, applicable to core power nodes such as medium-voltage AC/DC converters for AI parks, energy storage PCS and solid-state transformers (SSTs).
• IBB020A33GM4 full-bridge substrate-free WolfPACK module: Rated 3300V/20mΩ, equipped with aluminum nitride substrates and press-fit pins. Positioned as a scalable system building block, it is specially designed for multi-module series-parallel applications including cascaded H-bridges of SSTs and medium-voltage DC/DC converters.

The launch of these two modules marks the official spillover of SiC technology from low-voltage automotive applications to medium-voltage infrastructure. With the voltage level jumping from 800V to 3.3kV, the functional scope of busbars has undergone a fundamental shift. In traditional low-voltage systems, busbars only need to meet current-carrying and temperature rise requirements. However, modern medium-voltage SiC systems require advanced high conductivity busbar designs to achieve lower resistance, improved current distribution and higher energy efficiency.In contrast, busbars in medium-voltage SiC systems must fulfill four core functions simultaneously: electrical insulation isolation, parasitic parameter suppression, balanced current sharing across multiple modules, and EMI path management. These functions are deeply intertwined with four major engineering constraints of medium-voltage modules: partial discharge insulation, thermal management, gate drive design, and parasitic & EMI suppression.

Leveraging our self-developed multi-physics simulation platform (3D electromagnetic simulation and thermo-mechanical coupling simulation), A&J Link Technologies can pre-match electrical and mechanical parameters of 3.3kV SiC modules to resolve industry-wide pain points in one stop, such as concentrated electric fields in insulation, high loop stray inductance, unbalanced current across parallel branches and high-frequency common-mode interference. All our products pass full validation tests covering partial discharge, power cycling and EMC reliability.

Take insulation performance as an example. Although 3.3kV SiC modules feature 6kV AC housing isolation capability, the insulation reliability of the whole system depends on the full power chain. The interlayer insulation thickness, creepage distance and electrical clearance of busbars directly determine the partial discharge level of the power loop. All high-voltage laminated busbars from A&J Link Technologies adopt high-temperature PET/PI insulating films and R5 or larger rounded edge passivation processes. Creepage distances and electrical clearances are designed with a 1.5× safety margin for 3.3kV systems, and 100% of finished products undergo partial discharge testing at 10pC@3.3kV to eliminate insulation breakdown risks at the manufacturing stage.

II. Divergent Positioning of Dual Modules Defines New Busbar Design Paradigms

The distinct positioning of Wolfspeed’s two modules demands completely different busbar design philosophies. A&J Link Technologies provides customized low-inductance laminated busbar development and mass delivery services tailored to both module types.

1. Half-Bridge Modules with Substrate: Low-Parasitic Busbars for Heavy-Duty Scenarios

The HAB900C33LM4 supports high current up to 900A and is deployed in heavy-duty scenarios such as main power loops of SSTs. The core design objectives for corresponding busbars are extreme parasitic parameter reduction, reliable insulation and high electrical conductivity. Therefore, customized high conductivity busbar structures are essential for maintaining stable operation under high-current conditions.

• Laminated structure: Adopting tightly coupled positive and negative laminated busbars, the power loop area is reduced to 1/5 of that of discrete conventional busbars. Through symmetrical hot-press lamination of multi-layer copper foils, A&J Link Technologies stabilizes the total system stray inductance below 25nH (as low as under 20nH under extreme operating conditions), effectively suppressing L·di/dt voltage overshoot induced by high-speed SiC switching.
• Insulation and mechanical control: High-temperature PET/polyimide films are used for interlayer insulation with R5 rounded edges and a minimum creepage distance of 45mm. Precision CNC machining ensures hole position tolerance within ±0.02mm, paired with standardized torque assembly guidelines to avoid module damage caused by mechanical stress.
• Thermo-mechanical matching: Specially formulated copper alloys are selected to match the thermal expansion coefficients of modules and liquid-cooled heat sinks. A&J Link Technologies’s vacuum hot-press lamination process guarantees no deformation and a contact resistance variation rate ≤10% after 1,000 power cycling tests ranging from -40℃ to 125℃.

2. Substrate-Free Full-Bridge WolfPACK Modules: Scalable Busbars for Modular Systems

As system building blocks, IBB020A33GM4 modules are applied to cascaded H-bridge SSTs and similar topologies. Corresponding busbars prioritize modular expandability and high-precision current sharing.

• Zoned architecture: A standardized unit design consisting of 1 main sub-busbar paired with 2 full-bridge modules supports plug-and-play expansion, enabling rapid construction of cascaded topologies with 8 to 16 modules and drastically shortening system integration cycles.
• Current sharing control: Optimized via 3D electromagnetic simulation, impedance deviation between parallel branches is controlled within 3% (measured as low as 2.5% for A&J Link Technologies products), ensuring dynamic and static current sharing efficiency ≥95% to prevent overload failure of individual modules.
• Compatibility and shielding: A flatness tolerance of 0.1~0.2mm is reserved to accommodate pre-coated TIM (thermal interface material) and avoid cracking of epoxy encapsulation from excessive local pressure. An optional integrated aluminum shielding layer with grounding impedance ≤5mΩ diverts common-mode current excited by high dv/dt to ground, meeting high CMTI (common-mode transient immunity) requirements for gate drivers.

III. Four Core Design Principles for Medium-Voltage Busbars (Aligned with 3.3kV System Constraints)

Derived from the engineering constraints of Wolfspeed’s 3.3kV modules, A&J Link Technologies has established a systematic design framework for medium-voltage busbars, covering four key principles:

1. Partial Discharge Insulation as Top Priority: All metal edges are rounded; insulating materials with CTI ≥600 are adopted; 100% partial discharge testing at 10pC@3.3kV is implemented; heat sink flatness and assembly torque are strictly controlled to avoid air gaps triggering partial discharge after thermal cycling.
2. Co-Simulation of Parasitic Parameters: 3D co-simulation of busbars, DC-Link capacitors and module layouts is conducted to limit total stray inductance ≤30nH; integrated snubber capacitors can be embedded into busbars for further overvoltage suppression if needed.
3. Thermo-Mechanical Reliability Matching: Copper alloy materials are selected to match thermal expansion coefficients of SiC modules and heat sinks; products pass 1,000 power cycling tests from -40℃ to 125℃ with full-load temperature rise ≤40K.
4. Controllable EMI Paths: Grounding paths are kept short and low-impedance; integrated shielding and wave-absorbing structures are embedded to easily meet CISPR 32 Class A EMI standards.

IV. Practical Application: Medium-Voltage Busbar Solution for 10,000-GPU AI Clusters

A 10,000-GPU AI cluster adopts the power supply architecture: "10kV grid → SST → 2.5kV DC bus → medium-voltage DC/DC converter → 800V rack busbar". Its core SST stage employs 16 pieces of 3.3kV full-bridge modules to build a cascaded H-bridge topology, with a customized busbar solution successfully delivered by A&J Link Technologies:

• Input-side busbar: Double-layer laminated structure with creepage distance ≥60mm and partial discharge ≤10pC, complying with strict insulation requirements for grid-side equipment.
• Power loop busbar: Zoned laminated design with branch impedance deviation ≤2.8% and total stray inductance ≤10nH, resulting in switching voltage overshoot of only 7% (far below the 10% safety threshold).
• Shielding design: Integrated 0.5mm aluminum shielding layer with grounding impedance ≤5mΩ, delivering EMI performance 10dB better than the CISPR 32 Class A limit.

This system achieves an overall efficiency of 98.5%, 2.2 percentage points higher than traditional silicon-based power frequency transformer solutions, with a 40% improvement in power density. A&J Link Technologies has mass-produced and delivered multiple batches of busbars with identical specifications, fully verifying the technical and commercial value of the combination of 3.3kV SiC devices and customized laminated busbars.

Conclusion

The launch of Wolfspeed’s dual 3.3kV SiC modules signals a clear industry shift: competition in AI power supply systems is no longer centered on device conduction loss alone, but on overall medium-voltage system capability. The evolution of busbars perfectly embodies this trend—they have transformed from passive auxiliary conductive components into active core system parts requiring collaborative design with power devices, gate drives, thermal management and EMI suppression. As higher-voltage SiC modules gain wider adoption, busbar design and manufacturing capacity will become a core competitive advantage across the industry.

A&J Link Technologies will continue to deepen its research on high-performance laminated busbar technology, developing advanced high conductivity busbar solutions for AI data centers, solid-state transformers, energy storage PCS and other high-power applications. Supported by a full industrial chain covering simulation design, precision manufacturing and reliability testing, we provide integrated high-voltage low-inductance busbar solutions compatible with 3.3kV and higher SiC devices for AI data centers, solid-state transformers, energy storage PCS and other applications, helping industry players capture the dividends brought by medium-voltage power supply transformation. For practitioners in AI infrastructure, mastering the evolution logic of busbars and partnering with professional manufacturers with full-process customized R&D capabilities is the key to gaining a competitive edge in the future.

This paper mainly references official technical documents of Wolfspeed’s 3.3kV SiC power modules and industry research on medium-voltage AI power supply architectures. For more technical details, please contact A&J Link Technologies.