The rapid evolution of artificial intelligence (AI) has driven significant advancements in server power supply units (PSUs). With increasing power demands, efficiency requirements, and the need for modularity, the interleaved totem pole (TTP) power factor correction (PFC) topology has emerged as a leading solution. This article explores the advantages of hybrid triangular current mode (TCM) and continuous current mode (CCM) control strategies in interleaved TTP PFCs, highlighting their role in revolutionizing high-power AI server PSUs.

人工智能的快速變革不停驅動著伺服器電源供應單元（PSUs）的重要改動。隨著功率需求、效率要求以及模塊化必要性的增加，該交錯式圖騰柱（TTP）功率因數(shù)校正（PFC）拓撲作為一款前沿解決方案興起。本文討論了混合三角電流模式（TCM）和連續(xù)電流模式（CCM）控制策略在交錯式TTP PFC中的優(yōu)勢，強調(diào)了其在革新高功率伺服器AI伺服器PSU中的重要性。

Background: Trends in AI Server PSUs

背景：AI服務器PSU趨勢

The AI server market is experiencing unprecedented growth, which lead to increasing power demand with single PSUpower levels projected to rise to 5.5–8 kW by 2025. This increase is driven by the adoption of GPUs supporting 48 V outputs, which have become the industry standard. For instance, AI servers such as the ASUS ESC-N8-E11 and NVIDIA HGX H100 require power levels 3–10 times higher than traditional servers. To meet these demands, advanced control strategies, including hybrid TCM/CCM, GaN and SiC technologies, are essential for achieving high efficiency, increasedpower density, and reliability.

AI服務器市場正經(jīng)歷爆發(fā)式增長，推動單電源模塊功率需求激增，預計2025年將躍升至5.5kW ~ 8kW。這一增長由支持48V輸出的GPU普及所推動，該標準已成行業(yè)規(guī)范。例如華碩ESC-N8-E11及英偉達HGX H100等AI服務器，其功耗需求已達傳統(tǒng)服務器的3至10倍。為滿足需求，必須采用混合TCM/CCM模式、氮化鎵/碳化硅技術等先進控制策略，方能實現(xiàn)高效能、高功率密度與卓越可靠性。

Hybrid TCM/CCM Control

混合TCM/CCM控制

Figure 1: Totem pole PFC architecture

圖1：圖騰柱PFC架構

Hybrid TCM/CCM control combines the strengths of both modes to optimize efficiency across varying load conditions. Key features include:

混合TCM/CCM控制涵括了兩類模式的雙重優(yōu)勢，基于多種負載工況優(yōu)化效率。關鍵特征包括：

 · Optimized efficiency:

   · The hybrid strategy can switch between TCM and CCM based on load conditions, optimizing efficiency across a wide range of operating points.

   · TCM is more efficient at light loads due to reduced switching losses, while CCM is more efficient at higher loads due to lower conduction losses.

 · 能效更高：

   · 該混合策略可基于負載工況在TCM與CCM模式間動態(tài)切換，實現(xiàn)寬范圍工作點的能效優(yōu)化。

   · TCM模式在輕載工況下因開關損耗降低而能效更優(yōu)，而CCM模式在重載時憑借導通損耗減少實現(xiàn)更高效率。

 · Reduced ripple current:

   · Interleaving two phases helps in significantly reducing the input and output current ripple.

   · The hybrid approach can further optimize ripple reduction by dynamically adjusting the operating mode.

 · 紋波電流更少：

   · 雙階段交錯協(xié)助大幅減少輸入及輸出電流紋波。

   · 該混合方案可通過動態(tài)調(diào)整工作模式來進一步優(yōu)化紋波減少。

 · Enhanced thermal management:

   · Distributing the load between two phases and switching between TCM and CCM can lead to better thermal performance and more balanced heat dissipation.

 · 熱管理更強：

   · 雙階段負載分配及TCM與CCM模式轉換可優(yōu)化熱性能并促使熱耗散更加均衡。

 · Improved transient response:

   · The ability to switch between TCM and CCM allows the system to quickly adapt to changes in load, providing a better transient response.

 · 瞬態(tài)響應更佳:

   · TCM與CCM模式的切換功能會讓系統(tǒng)更快適應負載變化，帶來更快的瞬態(tài)響應。

 · Flexibility and reliability:

   · The hybrid control strategy offers flexibility in design and application, making it suitable for various operating conditions.

   · It can enhance the reliability of the PFC circuit by reducing stress on components and improving thermal management.

 · 靈活性與可靠性：

   · 該混合控制策略提供設計與應用的雙重靈活性，廣泛適配多變工況。

   · 通過降低元件應力與優(yōu)化熱管理，顯著提升PFC電路可靠性。

Figure 2: Comparison of TCM/CCM in control strategy

圖2：TCM/CCM控制策略對比

Implementation in Interleaved TTP PFC

交錯式TTP PFC中的應用

The interleaved TTP PFC topology leverages hybrid TCM/CCM control to achieve superior performance. Key design parameters include:

 · Switching Frequency Range: 50–180 kHz

 · Input Voltage: 180–305 VAC

 · Target Efficiency: Peak efficiency of 99.2% and full-load efficiency of 98.6%

該交錯式TTP拓撲采用混合TCM/CCM控制以達到優(yōu)越性能。關鍵設計參數(shù)包括：

 · 開關頻率范圍： 50–180 kHz

 · 輸入電壓：180–305 VAC

 · 目標效率：峰值效率99.2%；全負載效率98.6%

Control Strategy and Key Features

控制策略及關鍵特點

The hybrid TCM/CCM control strategy is implemented using advanced components such as the STM32G474 microcontroller. ST Power and Energy Competence Center offers 5.5kW advantages of hybrid TCM/CCM control in interleaved TTP PFC Reference Designbased on STM32G4 Digital Controller to fit this high growth market.

該混合TCM/CCM控制策略通過采用STM32G74微控制器等高級組件來實現(xiàn)。意法半導體電源與能源創(chuàng)新技術中心研發(fā)了基于STM32G4全數(shù)字控制的5.5kW混合TCM/CCM交錯式TTP PFC參考設計來滿足這一高增長需求。

This 5.5kW advantages of hybrid TCM/CCM control in interleaved TTP PFC reference design introduces a complete ST’s digital power solution for high power interleaved TTP PFC applications based on the Mixed mode control methods topology. Reference design topology is mostly used for AI server power ORV3 and MCRPS Server power applications.

該基于STM32G4全數(shù)字控制的5.5kW混合TCM/CCM交錯式TTP PFC參考設計基于混合模態(tài)控制拓撲，為高功率交錯TTP PFC應用提供完整的意法半導體數(shù)字電源解決方案。此參考設計拓撲主要面向AI服務器電源（ORV3/MCRPS標準）場景。

This reference design achieves larger than 99.2% peak efficiency by utilizing ST’s 650V, 40mohmSiC MOSFET’s and 600V, 30mohm HV MOSFET’s which is TOLL package. It features fully digital control, with the STM32G474mixed-signal high performance microcontroller. Providing the control mode is operated in Interleaved Mixed Mode Totem Pole PFC control. Operating interleaved to reduce ripple current and reduce output capacitance value. When the load is below half load, the TCM is operated and ZVS is achieved, effectively improvingefficiency. When the load is higher than half load, it operates in CCM and effectively reduces the inductor current ripple, thereby reducing conduction loss.And at full load PF higher than 0.98, iTHD lower than 5%. We also have increasedSTPM32 (Metering solution) on our PFC stage. And verify that it is fully functional.

該參考設計采用意法半導體650V/40mΩ SiC MOSFET與600V/30mΩ高壓MOSFET（TOLL封裝），峰值效率突破99.2%，結合STM32G474混合信號高性能微控制器實現(xiàn)全數(shù)字化控制。方案采用交錯式混合模式圖騰柱PFC控制，通過交錯運行降低紋波電流并縮減輸出電容容值。半載以下負載啟用TCM，實現(xiàn)ZVS，高效提升能效；半載以上切換至CCM，顯著抑制電感電流紋波，降低導通損耗。滿載工況下PF＞0.98，iTHD＜5%。我們更在PFC級集成STPM32計量方案，并驗證其功能完備性。

With very competitive features:

 · Interleaved TTP PFC converter with Mixed mode control TCM/CCM topology

 · Input AC Voltage: 208 to 277VAC

 · Input AC Frequency: 47Hz to 63Hz

 · Output range: DC voltage 400 to 420 VDC

 · Maximum power: 5.5 kW

 · Peak efficiency>99.2%(Rated 230VAC)

 · High switching frequency operation (50kHz~180kHz)

 · Power Factor > 0.98 @ 100% load

 · iTHD < 5% @ 100% load

 · STPM32 (Metering solution)

具有極具競爭力的優(yōu)勢：

 · 交錯TTP PFC 轉換器帶混合模式控制TCM/CCM拓撲

 · 輸入AC電壓：208~277 VAC

 · 輸入AC頻率： 47Hz ~ 63Hz

 · 輸出范圍：DC 電壓400 ~ 420 V

 · 最大功率： 5.5 kW

 · 峰值效率>99.2%(額定230VAC)

 · 高開關頻率工作 (50kHz~180kHz)

 · 功率因數(shù)> 0.98 @ 100%負載

 · iTHD < 5% @ 100%負載

 · STPM32 (計量方案)

Platform overview

平臺概覽

Figure 3: System Architecture of mixed mode control in interleaved TTP PFC

圖3：交錯式TTP PFC混合模式控制系統(tǒng)架構

Digital control provides a mixed mode control of both TCM and CCM for light-load to full-load conditions, the maximum efficiency 208Vac~277Vac and the load is from 10% to 100%, the efficiency can reach 97.88% at 10% load and over 98.46% at 100% full load. PF can also be satisfied above 0.987. The iTHD meet spec at full load 5.5KW (<5%@5.5 kW). As shown in Figure 4, The efficiency graph measured when the input voltage is from 208Vac to 277Vac. The peak efficiency is above 99.2% and the full load efficiency is above 98.4% and the iTHD under 5% in Figure5.

數(shù)字控制系統(tǒng)實現(xiàn)輕載至滿載工況下TCM與CCM混合模態(tài)控制。當208~277Vac輸入且10%至100%負載范圍內(nèi)，系統(tǒng)最高效率達10%輕載97.88%、滿載超98.46%。PF亦可穩(wěn)定高于0. 987。iTHD符合規(guī)范，在5.5kW滿載工況下＜5%。如圖4所示，208~277Vac輸入時系統(tǒng)效率曲線顯示：峰值效率＞99.2%，滿載效率＞98.4%；圖5驗證滿載iTHD穩(wěn)定低于5%。

Figure 4: Efficiency diagram of different input voltage measurements

圖4:不同輸入電壓測量的效率曲線圖

Figure 5: iTHD diagram of different input voltage measurements

圖5：不同輸入電壓測量的iTHD曲線圖

Summary

總結

Higher power level PSU is a new trend for AI server driven by AI technology. The hybrid TCM/CCM control strategy in interleaved TTP PFCs offers a comprehensive solution for high-power AI server PSUs. By combining the strengths of both modes, this approach achieves higher efficiency, reduced ripple current, enhanced thermal management, and improved reliability. ST provides tailored design kits, 5.5 kW and 8 kW AI server PSUreference design and a comprehensive product portfolio to support the development of next-generation AI server PSUs.

高功率電源（PSU）是AI技術驅動的AI服務器新趨勢。交錯式TTP PFC中的混合TCM/CCM控制策略，為高功率AI服務器電源提供全棧解決方案。該方案融合雙模優(yōu)勢，實現(xiàn)更高能效、更低紋波電流、更強熱管理及更優(yōu)可靠性。意法半導體提供定制設計套件（5.5kW/8kW AI服務器電源參考設計）及完整產(chǎn)品組合，賦能新一代AI服務器電源開發(fā)。

For more information, visit STMicroelectronics.

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