封面
市場調查報告書
商品編碼
2148259

全球電動車車載充電器市場規模、佔有率及成長預測(2026-2031年)

Global EV On-Board Charger Market Size, Share & Growth Forecast (2026-2031)

出版日期: | 出版商: Knowledge Sourcing Intelligence | 英文 153 Pages | 商品交期: 最快1-2個工作天內

價格
簡介目錄

全球電動車車載充電器市場預計到 2026 年將達到 84.5 億美元,預計到 2031 年將達到 183.5 億美元。這意味著在預測期內,複合年成長率將達到 16.8%。

隨著電動車產量的擴大和充電需求的日益複雜,全球電動車車載充電器市場在車輛電氣化過程中扮演著越來越重要的角色。車載充電器將電網提供的交流電 (AC) 轉換為車輛電池所需的受控直流電 (DC)。它們還具備功率因數校正、電氣隔離、電壓轉換、電池通訊和安全管理等功能。雖然直流快速充電在很大程度上無需車載充電器,但交流充電在住宅、職場和目的地等場所的充電中仍然發揮著至關重要的作用。

電動車產量的擴張直接推動了車載電源單元(OBC)的年度需求成長。預計到2025年,電動車的銷量將超過2,000萬輛,到2026年將達到約2,300萬輛。同時,每輛車的OBC組件價值也在改變。雖然低功率單元在大眾市場車型中仍然很重要,但11千瓦和22千瓦的系統正擴大應用於高階車型、商用車以及三相交流電普及的市場。此外,這項技術正朝著雙向充電、800伏特相容性、寬能隙半導體和整合電力電子架構的方向發展。

市場促進因素

電動車產量的擴大將直接促進車載信用卡(OBC)的需求。

  • 最強勁的市場促進因素是插電式汽車產量的成長。無論是電池式電動車(BEV) 或插電式混合動力汽車(PHEV),除非採用專用充電架構,否則都需要交流充電。這使得電動車產量與車載充電單元 (OBC) 的需求之間形成了直接連結。
  • 預計到2026年,電池式電動車(OBC)市場約58.3億美元的需求。乘用車約佔市場佔有率的91%,反映了全球電動車的高產量。隨著車隊營運商擴大採用電動巴士和卡車,商用車領域也湧現出更多機會。
  • 中國憑藉其大規模的電動車生產和銷售基地,仍然是一個極為重要的市場。到2025年,中國電動車銷量將超過1,300萬輛。中國本土汽車、電池、半導體和電力電子產品的大規模生產,既滿足了國內車載電池的需求,也促進了區域生產。

交流充電輸出功率的提高,使得可以安裝更多的電子元件。

  • 人們對電動車充電的期望正從3.3千瓦和6.6千瓦的系統轉向11千瓦和22千瓦的平台。高功率的車載充電站(OBC)需要更先進的開關元件、磁性元件、濾波器、溫度控管和控制系統。
  • 特別是 11 千瓦至 22 千瓦的細分市場預計將經歷快速成長,預計到 2031 年將接近 44 億美元。這一細分市場的成長動力來自高階汽車、商用車和高規格電動車平台的需求,以及三相交流充電的普及。
  • 隨著充電輸出功率的提升,高效率的溫度控管和緊湊的封裝設計也變得愈發重要。車載充電器供應商必須在確保電磁相容性、安全性和可靠性的前提下,實現更高的功率密度,以滿足汽車應用的需求。

雙向充電帶來的新功能潛力

  • 雙向車載通訊 (OBC) 使得車輛電池向外部負載或電網反向輸送電力成為可能。 「V2L(車輛到負載)」、「V2H(車輛到家庭)」和「V2G(車輛到電網)」等應用程式正在創造超越傳統電池充電的新功能。
  • 預計到 2031 年,雙向車載通訊市場規模將達到 64.2 億美元。該細分市場預計將實現最快成長,到 2031 年的年複合成長率(CAGR)約為 33.4%。
  • 這項技術需要額外的硬體和軟體來實現反向功率轉換、電網同步、保護、通訊和能源管理。隨著原始設備製造商 (OEM) 開發用於能源服務和備用電源應用的車輛,雙向功能正成為車載電腦 (OBC) 平台開發中日益重要的組成部分。

市場限制因素

直流快速充電限制了對高功率交流電的需求。

  • 公共直流快速充電樁可以繞過車輛的車載電腦(OBC),提供比交流電充電系統高得多的充電功率。隨著超快速充電網路的擴展,汽車製造商未必需要提高所有車型的車載電腦輸出功率。
  • 對於許多應用場景而言,7 kW 至 11 kW 的車載充電樁 (OBC) 仍然足以滿足夜間或職場的充電需求。提高 OBC 的輸出功率會增加成本、重量、冷卻需求和系統複雜性。這實際上限制了高功率交流充電的擴展規模。
  • 因此,車載電腦市場的成長預計不會由交流輸出的無限成長所驅動,而是由電動車銷量的成長、高價值半導體的採用、雙向功能和系統整合所驅動。

此次整合將提高認證和設計要求。

  • 將車載電腦 (OBC) 與直流/直流轉換器、配電單元以及充電和通訊系統整合,可減少對機殼、連接器、佈線、散熱介面和組裝工作的需求。然而,這種整合也增加了供應商的責任。
  • 整合式高壓電源箱必須滿足多項功能要求,包括隔離、電磁相容性、散熱設計、功能安全和網路安全。這可能導致原始設備製造商 (OEM) 進行漫長的認證週期。此外,設計變更可能同時影響車輛的多個子系統。
  • 這些要求有利於擁有成熟的汽車品質系統、電力電子專業知識、軟體開發能力和本地製造支援的供應商。

目錄

第1章:執行摘要

第2章:市場概述

  • 市場概覽
  • 市場區隔

第3章:商業環境

  • 市場促進因素
    • 電動車產量的擴大直接推動了車載充電器(OBC)的年需求量。
    • 空調充電輸出功率的提高,使得每台空調機組可安裝的電子設備容量更大。
    • 雙向充電創造了一種新的功能性收入來源。
  • 市場限制因素
    • 直流快速充電減少了對高功率交流車載充電器(OBC)的需求。
    • 此次整合將增加認證風險和供應商責任。
  • 市場機遇
  • 波特五力分析
  • 產業價值鏈分析
  • 政策、收費標準和功能安全

第4章 技術展望

  • 使用矽、碳化矽和氮化鎵的電力電子裝置
  • 雙向充電和V2X
  • 整合車載電腦、直流/直流轉換器和配電
  • 相容800V電壓,高功率交流充電

第5章:全球電動車車用充電器市場:額定功率

  • 7.4千瓦或以下
  • 7.4千瓦至11千瓦
  • 11千瓦至22千瓦
  • 22千瓦或以上

第6章:全球電動車車用充電器市場:依動力類型分類

  • 電池式電動車(BEV)
  • 插電式混合動力車(PHEV)

第7章 全球電動車車用充電器市場:依車輛類型分類

  • 搭乘用車
  • 商用車輛

第8章 全球電動車車用充電器市場:依架構分類

  • 獨立式車上電腦
  • 整合式車用電腦 + 直流/直流/高壓電源箱

第9章:全球電動車車用充電器市場:依方向分類

  • 單向
  • 雙向

第10章:全球電動車車用充電器市場:以功率半導體分類

  • 矽
  • 碳化矽(SiC)
  • 氮化鎵(GaN)

第11章 全球電動車車用充電器市場:按地區分類

  • 北美洲
    • 美國
    • 加拿大
    • 墨西哥
  • 南美洲
    • 巴西
    • 阿根廷
    • 其他南美國家
  • 歐洲
    • 德國
    • 英國
    • 法國
    • 挪威
    • 其他歐洲國家
  • 中東和非洲
    • 沙烏地阿拉伯
    • 阿拉伯聯合大公國
    • 南非
    • 其他中東和非洲國家
  • 亞太地區
    • 中國
    • 日本
    • 韓國
    • 印度
    • 東南亞
    • 其他亞太國家

第12章:競爭環境與分析

  • 主要公司及策略分析
  • 市佔率分析
  • 合約、專案和夥伴關係
  • 競爭環境儀錶板

第13章:公司簡介

  • Valeo
  • BorgWarner Inc.
  • Robert Bosch GmbH
  • Delta Electronics, Inc.
  • Schaeffler AG
  • KOSTAL Automobil Elektrik GmbH & Co. KG
  • MAHLE GmbH
  • BRUSA HyPower AG
  • Bel Fuse Inc.
  • Toyota Industries Corporation
  • Ficosa Internacional SA
  • Lear Corporation
  • LG Magna e-Powertrain Co., Ltd.
  • Eaton Corporation plc
  • Hyundai Mobis Co., Ltd.
  • Shinry Technologies Co., Ltd.
  • innolectric AG
  • Stercom Power Solutions GmbH

第14章 近期趨勢

第15章附錄

簡介目錄
Product Code: KSI-009285

The global EV on-board charger market is estimated at USD 8.45 billion in 2026 and is projected to reach USD 18.35 billion by 2031, representing a CAGR of 16.8% during the forecast period.

The global EV on-board charger market is becoming an increasingly important part of vehicle electrification as electric vehicle production expands and charging requirements become more sophisticated. An on-board charger converts AC electricity from the grid into the controlled DC power required by the vehicle battery. It also performs power-factor correction, galvanic isolation, voltage conversion, battery communication, and safety management. While DC fast charging largely bypasses the OBC, AC charging remains important for residential, workplace, and destination charging.

The growth of electric vehicle production directly expands annual OBC demand. More than 20 million electric cars were sold in 2025, with approximately 23 million expected in 2026. At the same time, the value of OBC content per vehicle is changing. Lower-power units remain important in mass-market vehicles, while 11 kW and 22 kW systems are gaining adoption in premium vehicles, commercial applications, and markets with three-phase AC availability. The technology is also moving toward bidirectional charging, 800 V compatibility, wide-bandgap semiconductors, and integrated power-electronics architectures.

Market Drivers

Electric Vehicle Production Directly Expands OBC Demand

  • The strongest market driver is the increasing production of plug-in vehicles. Both battery electric vehicles and plug-in hybrid electric vehicles require an AC charging pathway unless they use a specialized charging architecture. This creates a direct relationship between EV production and OBC unit demand.
  • Battery electric vehicles account for approximately USD 5.83 billion of OBC demand in 2026. Passenger cars represent about 91% of the vehicle-type market, reflecting the high volume of global electric-car production. Commercial vehicles provide an additional opportunity as fleet operators increasingly adopt electric buses and trucks.
  • China remains especially important because of its large electric vehicle production and sales base. More than 13 million electric cars were sold in China during 2025. The scale of local vehicle, battery, semiconductor, and power-electronics manufacturing supports both domestic OBC demand and regional production.

Higher AC Charging Power Raises Electronics Content

  • EV charging expectations are moving beyond 3.3 kW and 6.6 kW systems toward 11 kW and 22 kW platforms. Higher-power OBCs require more capable switching devices, magnetics, filtering, thermal management, and control systems.
  • The 11 kW to 22 kW segment is expected to grow particularly quickly. It is projected to approach USD 4.40 billion by 2031. The segment benefits from three-phase AC charging availability and demand from premium, commercial, and higher-specification EV platforms.
  • Higher charging power also increases the importance of efficient thermal management and compact packaging. OBC suppliers must deliver greater power density while maintaining electromagnetic compatibility, safety, and automotive reliability.

Bidirectional Charging Creates New Functional Opportunities

  • Bidirectional OBCs enable electricity to flow from the vehicle battery back to an external load or electrical network. Vehicle-to-load, vehicle-to-home, and vehicle-to-grid applications are creating additional functionality beyond conventional battery charging.
  • Bidirectional OBCs are projected to approach USD 6.42 billion by 2031. The segment is expected to record the fastest growth, with approximately 33.4% CAGR through 2031.
  • The technology requires additional hardware and software for reverse power conversion, grid synchronization, protection, communication, and energy management. As OEMs prepare vehicles for energy services and backup-power applications, bidirectional functionality is becoming a more important part of OBC platform development.

Market Restraints

DC Fast Charging Limits the Need for Very High AC Power

  • Public DC fast charging bypasses the vehicle's OBC and can provide much higher charging power than AC systems. As ultra-fast charging networks expand, automakers do not necessarily need to increase OBC power across every vehicle segment.
  • A 7 kW to 11 kW OBC can remain adequate for overnight and workplace charging in many applications. Increasing OBC power adds cost, weight, cooling requirements, and system complexity. This creates a practical limit on the extent to which very high-power AC charging can expand.
  • Consequently, OBC market growth is expected to come from increasing EV volumes, higher-value semiconductor content, bidirectional functionality, and system integration rather than an unrestricted move toward higher AC power.

Integration Increases Qualification and Engineering Requirements

  • OBC integration with DC/DC converters, power distribution units, and charging communication systems can reduce housings, connectors, cabling, cooling interfaces, and assembly operations. However, integration also increases supplier responsibility.
  • An integrated high-voltage power box must satisfy isolation, electromagnetic compatibility, thermal, functional safety, and cybersecurity requirements across multiple functions. OEM qualification cycles can therefore be lengthy. A design modification can also affect several vehicle subsystems simultaneously.
  • These requirements favor suppliers with established automotive quality systems, power-electronics expertise, software capabilities, and local manufacturing support.

Technology and Segment Insights

Power Rating

  • Up to 7.4 kW is the largest power-rating segment, accounting for approximately 43% of global OBC revenue in 2026 and generating around USD 3.63 billion. The segment includes 3.3 kW, 6.6 kW, 7 kW, and 7.4 kW configurations.
  • Its broad use reflects compatibility with single-phase residential electricity, adequate overnight charging, lower cost, and lower thermal requirements. The segment will continue to grow in absolute value, although its share is expected to decline as 11 kW and 22 kW systems gain adoption.
  • The above 11 kW to 22 kW category is the fastest-growing power band. It is projected to record approximately 23.7% CAGR through 2031. Above 22 kW remains a smaller and more specialized segment.

Propulsion Type

  • Battery electric vehicles represent approximately 69% of the OBC market in 2026. Their larger production volumes and higher charging-power content make them the primary source of demand.
  • Plug-in hybrid electric vehicles form the second propulsion segment. Their OBC requirements depend on battery capacity, charging architecture, and the design of the hybrid powertrain.

Vehicle Type

  • Passenger cars dominate the market and account for approximately USD 7.69 billion in 2026. Their strong position reflects the large number of passenger EVs entering production globally.
  • Commercial vehicles represent a smaller segment but provide opportunities for higher-value OBC systems. Fleet operators can place greater emphasis on charging speed and vehicle availability, supporting demand for higher-power charging systems.

Architecture

  • Standalone OBCs remain widely used, particularly in vehicle platforms where charging is packaged as a dedicated function. However, integrated OBC, DC/DC, and high-voltage power-box architectures are gaining rapidly.
  • Integrated systems represent approximately 38% of the market in 2026 and are projected to grow at about 23.4% CAGR through 2031. Combining multiple high-voltage functions can reduce packaging volume, wiring, connectors, assembly requirements, and duplicated cooling systems.

Directionality

  • Unidirectional OBCs remain the established architecture. Bidirectional systems are expanding rapidly because they support V2L, V2H, and V2G functionality.
  • Bidirectional OBCs represent approximately 18% of the market in 2026. Their adoption will depend on charging standards, utility requirements, OEM activation, grid integration, and energy-management systems.

Power Semiconductor

  • Silicon remains an established semiconductor technology for conventional OBC platforms. Silicon carbide is gaining share in higher-voltage and higher-power systems because of its switching efficiency and power-density benefits. SiC represents approximately 38% of the market in 2026.
  • Gallium nitride is developing rapidly for higher-frequency and compact OBC architectures. Its ability to support higher switching frequencies can reduce the size of passive components and contribute to more compact designs.

Geography

  • Asia Pacific accounts for approximately 60% of global OBC revenue in 2026, generating around USD 5.07 billion. China is the principal regional driver because of its large EV production and sales base and its established power-electronics ecosystem.
  • Japan and South Korea have strong automotive electronics and semiconductor capabilities. India and Southeast Asia are expanding from smaller bases as EV production increases. OBC localization in India is also developing alongside new electrification programs.
  • Europe remains an important market because three-phase AC charging supports wider use of 11 kW and 22 kW systems. North America provides opportunities through increasing EV adoption, charging infrastructure development, and higher-value vehicle platforms. South America and the Middle East and Africa remain smaller markets with developing EV adoption.

Competitive and Strategic Outlook

  • The competitive landscape includes global Tier 1 automotive suppliers, specialist high-voltage power-electronics companies, and vertically integrated vehicle groups. Major companies include Valeo, BorgWarner, Robert Bosch, Delta Electronics, Schaeffler, KOSTAL, MAHLE, BRUSA HyPower, Bel Fuse, Toyota Industries, Ficosa, Lear, LG Magna e-Powertrain, Eaton, Hyundai Mobis, Shinry Technologies, innolectric, and Stercom Power Solutions.
  • Competition is shifting toward power density, conversion efficiency, bidirectionality, 800 V compatibility, functional integration, software, cybersecurity, and localized production. Suppliers are increasingly expected to provide flexible platforms capable of supporting different battery voltages and charging-power requirements.
  • System integration is one of the strongest strategic themes. Valeo, Delta, Bosch, and Schaeffler offer architectures combining OBCs with DC/DC converters and other high-voltage functions. Such systems increase supplier content per vehicle while helping OEMs reduce electronic complexity.
  • Wide-bandgap semiconductor technology is also influencing competition. SiC is already established in high-voltage automotive power electronics, while GaN is progressing toward higher-power automotive conversion. The selection between silicon, SiC, and GaN increasingly depends on total system efficiency, thermal requirements, magnetics, cost, packaging, and supply security.

800 V compatibility is another important competitive factor. OBC suppliers increasingly need platforms capable of supporting different battery-voltage classes. Flexible designs can help OEMs use common power-electronics architectures across multiple vehicle platforms.

  • Recent developments further demonstrate the direction of the market. Valeo is expanding bidirectional OBC capabilities and localizing OBC and DC/DC combination units in India. Schaeffler has presented an 800 V multifunctional power-electronics concept. Delta continues to expand standalone, bidirectional, and integrated OBC/DC/DC solutions. Development of compact 22 kW GaN OBCs is also supporting the transition toward higher power density.

Conclusion

  • The global EV on-board charger market is projected to grow from USD 8.45 billion in 2026 to USD 18.35 billion by 2031 at a CAGR of 16.8%. Rising EV production will remain the fundamental source of demand, while higher AC charging power, bidirectional functionality, wide-bandgap semiconductors, and integrated power-electronics architectures will increase value per vehicle. Up to 7.4 kW systems will remain important because of their broad application, while 11 kW and 22 kW systems will expand in higher-specification platforms. Integrated OBC and DC/DC architectures and bidirectional systems are expected to grow particularly rapidly. Asia Pacific will remain the largest regional market, supported by China's EV manufacturing scale and the broader Asian automotive electronics ecosystem.

Key Benefits of this Report

  • Insightful Analysis: Detailed market insights across regions, customer segments, policies, socio-economic factors, consumer preferences, and industry verticals.
  • Competitive Landscape: Understand strategic moves by key players to identify optimal market entry approaches.
  • Market Drivers and Future Trends: Assess major growth forces and emerging developments shaping the market.
  • Actionable Recommendations: Support strategic decisions to unlock new revenue streams.
  • Caters to a Wide Audience: Suitable for startups, research institutions, consultants, SMEs, and large enterprises.

What Businesses Use Our Reports For

  • Industry and market insights, opportunity assessment, product demand forecasting, market entry strategy, geographical expansion, capital investment decisions, regulatory analysis, new product development, and competitive intelligence.

Report Coverage

  • Historical data from 2021 to 2024, Base year 2025, and Forecast years from 2026 to 2031
  • Growth opportunities, challenges, supply chain outlook, regulatory framework, and trend analysis
  • Competitive positioning, strategies, and market share evaluation, and trade analysis
  • Revenue growth and forecast assessment across segments and regions
  • Company profiling including strategies, products, financials, and key developments

TABLE OF CONTENTS

1. EXECUTIVE SUMMARY

2. MARKET SNAPSHOT

  • 2.1. Market Overview
  • 2.2. Market Segmentation

3. BUSINESS LANDSCAPE

  • 3.1. Market Drivers
    • 3.1.1. Electric Vehicle Production Directly Expands Annual OBC Unit Demand
    • 3.1.2. Higher AC Charging Power Raises Electronics Content per Vehicle
    • 3.1.3. Bidirectional Charging Creates a New Functional Revenue Layer
  • 3.2. Market Restraints
    • 3.2.1. DC Fast Charging Can Reduce the Need for Very High AC OBC Power
    • 3.2.2. Integration Increases Qualification Risk and Supplier Responsibility
  • 3.3. Market Opportunities
  • 3.4. Porter's Five Forces Analysis
  • 3.5. Industry Value Chain Analysis
  • 3.6. Policies, Charging Standards and Functional Safety

4. TECHNOLOGICAL OUTLOOK

  • 4.1. Silicon, Silicon Carbide and Gallium Nitride Power Electronics
  • 4.2. Bidirectional Charging and V2X
  • 4.3. Integrated OBC, DC/DC and Power Distribution
  • 4.4. 800 V Compatibility and Higher-Power AC Charging

5. GLOBAL EV ON-BOARD CHARGER MARKET BY POWER RATING

  • 5.1. Up to 7.4 kW
  • 5.2. Above 7.4 kW to 11 kW
  • 5.3. Above 11 kW to 22 kW
  • 5.4. Above 22 kW

6. GLOBAL EV ON-BOARD CHARGER MARKET BY PROPULSION TYPE

  • 6.1. Battery Electric Vehicles (BEVs)
  • 6.2. Plug-in Hybrid Electric Vehicles (PHEVs)

7. GLOBAL EV ON-BOARD CHARGER MARKET BY VEHICLE TYPE

  • 7.1. Passenger Cars
  • 7.2. Commercial Vehicles

8. GLOBAL EV ON-BOARD CHARGER MARKET BY ARCHITECTURE

  • 8.1. Standalone OBC
  • 8.2. Integrated OBC + DC/DC / High-Voltage Power Box

9. GLOBAL EV ON-BOARD CHARGER MARKET BY DIRECTIONALITY

  • 9.1. Unidirectional
  • 9.2. Bidirectional

10. GLOBAL EV ON-BOARD CHARGER MARKET BY POWER SEMICONDUCTOR

  • 10.1. Silicon
  • 10.2. Silicon Carbide (SiC)
  • 10.3. Gallium Nitride (GaN)

11. GLOBAL EV ON-BOARD CHARGER MARKET BY GEOGRAPHY

  • 11.1. North America
    • 11.1.1. United States
    • 11.1.2. Canada
    • 11.1.3. Mexico
  • 11.2. South America
    • 11.2.1. Brazil
    • 11.2.2. Argentina
    • 11.2.3. Rest of South America
  • 11.3. Europe
    • 11.3.1. Germany
    • 11.3.2. United Kingdom
    • 11.3.3. France
    • 11.3.4. Norway
    • 11.3.5. Rest of Europe
  • 11.4. Middle East and Africa
    • 11.4.1. Saudi Arabia
    • 11.4.2. United Arab Emirates
    • 11.4.3. South Africa
    • 11.4.4. Rest of Middle East and Africa
  • 11.5. Asia Pacific
    • 11.5.1. China
    • 11.5.2. Japan
    • 11.5.3. South Korea
    • 11.5.4. India
    • 11.5.5. Southeast Asia
    • 11.5.6. Rest of Asia Pacific

12. COMPETITIVE ENVIRONMENT AND ANALYSIS

  • 12.1. Major Players and Strategy Analysis
  • 12.2. Market Share Analysis
  • 12.3. Agreements, Programs and Collaborations
  • 12.4. Competitive Dashboard

13. COMPANY PROFILES

  • 13.1. Valeo
  • 13.2. BorgWarner Inc.
  • 13.3. Robert Bosch GmbH
  • 13.4. Delta Electronics, Inc.
  • 13.5. Schaeffler AG
  • 13.6. KOSTAL Automobil Elektrik GmbH & Co. KG
  • 13.7. MAHLE GmbH
  • 13.8. BRUSA HyPower AG
  • 13.9. Bel Fuse Inc.
  • 13.10. Toyota Industries Corporation
  • 13.11. Ficosa Internacional SA
  • 13.12. Lear Corporation
  • 13.13. LG Magna e-Powertrain Co., Ltd.
  • 13.14. Eaton Corporation plc
  • 13.15. Hyundai Mobis Co., Ltd.
  • 13.16. Shinry Technologies Co., Ltd.
  • 13.17. innolectric AG
  • 13.18. Stercom Power Solutions GmbH

14. RECENT DEVELOPMENTS

15. APPENDIX

  • 15.1. Currency
  • 15.2. Assumptions
  • 15.3. Base and Forecast Years Timeline
  • 15.4. Abbreviations