In 1975, the fuel rod changer at the Loviisa nuclear power plant and the Karihaara sawmill in Finland became the first applications to be equipped with SAMI A frequency converters from Strömberg’s electronics workshop in Helsinki, Finland. This marked the beginning of the AC LV drive's success story, which has since grown and evolved into a global standard in the industry.

For 50 years, ABB’s low voltage drives have been a part of many era-defining technologies and breakthroughs - from electric public transport to today’s push for energy-efficient, low-carbon industries. Our passion for solving technical challenges has always inspired our innovation. This anniversary celebrates how LV drives impacted on the world around us. Low voltage drives story continues, with the next chapters already being written on the desks of our bright minds. 

VideoThe journey through time: 50 years of LV drivesWatch the video →

Web storyMartti Harmoinen and the invention that changed industry Read the story →

VideoThe Strömberg story of SAMI: From the Helsinki subway to an industrial success with low-frequency AC drives from the 1970s. Watch the video →
1960's

Research, engineering, and pioneering work began at the electric laboratory in Pitäjänmäki, Finland.

    • The Strömberg Electronics Group and Department was established. Focus was placed on developing DC drive control systems based on thyristors and analog electronics. A variety of other control products using thyristor and analog technologies were also developed.
    • AC drives were already seen as a future solution, as highlighted in technical publications.
    • Development of Strömberg’s first AC drive began in 1969: a 2-level voltage source inverter (VSI) frequency converter based on fast thyristors, pulse width modulation (PWM) — a technique that controls motor voltage and frequency by adjusting the width of voltage pulses — and analog electronics.
1970's

Strömberg intensified AC drive development for industrial and traction applications.

  • 1973
    • AC drive development for the Helsinki Metro officially began through cooperation with Metrovaunut Oy.
  • 1974
    • The SAMI A frequency converter was developed.
  • 1975
    • SAMI A was launched to the market. The first delivery took place in September–October: three units (350 kVA, 500 V) to the Karihaara sawmill in Northern Finland, the first commercial application of Strömberg’s AC drive.
    • Early applications also included a fuel rod replacement device at the Loviisa nuclear power plant.
    • SAMI A represented the first high-power PWM drive.
  • 1979
    • Strömberg AC drives successfully passed Helsinki Metro train tests, confirming maturity for demanding traction use.
1980's
  • 1981
    • Martti Harmoinen received Finland’s first engineering award for underground train AC drive technology.
    • The SAMI B product was launched, with the first delivery to a Yhtyneet Paperitehtaat paper machine in Finland.
  • 1982
    • Helsinki Metro began operation on August 2. SAMI converters developed by Strömberg powered the trains.
  • 1985
    • The SAMI F (SAMI STAR) was introduced, featuring gate-commutated power electronics, modular design, microprocessor-based digital control, vector control, space vector modulation, advanced HMI panel, and PLC communication.
    • SAMI D (MEGA STAR) was introduced, with the first eight units delivered to a gas pipeline landing vessel in Finland.
    • A 3-level NPC medium-voltage converter was developed using GTO-thyristors and space vector modulation.
  • 1986
    • ASEA acquired Kymi-Strömberg.
  • 1988
    • ASEA and Brown Boveri merged to form ABB Inc., with Strömberg Drives taking global responsibility for AC drive R&D.
  • 1989
    • ABB began AC drive production in New Berlin, Wisconsin.
1990's

Engineering focus expanded toward drive functionality and energy efficiency.

  • 1990
    • Commercialization of Insulated Gate Bipolar Transistors (IGBTs) revolutionized AC drive technology. IGBTs became a central component of modern drives, enabling more compact, efficient, and high-performance solutions across a wide range of applications.
    • Professor Jayant Baliga, developer of the IGBT, was awarded the Millennium Technology Prize.
    • The 2-level IGBT-based voltage source inverter (VSI) topology became the industry standard for decades, supporting robust and flexible motor control.
  • 1992
    • The ACS500, ABB’s first general-purpose drive series based on IGBT technology, was launched.
    • ABB opened a new drive production facility in China.
  • 1995
    • ABB introduced the ACS600 product family for industrial applications, featuring Direct Torque Control (DTC), signal processors, ASICs, and IGBTs, enhancing energy efficiency and motor performance.
  • 1999
    • The ACS600 family was extended to high power levels, with air- and liquid-cooled variants and Multidrive systems.
2000's

Development focused on active front-end converters and advanced power electronics.

  • 2003
    • ABB launched the ACS800 product family.
  • 2004
    • ABB introduced the ACS550 standard drive series, expanding global production in the USA, China, and Finland.
    • The ACH550 variant was introduced for HVAC applications, featuring an intuitive user interface.
  • 2005
    • The ACS800 R8 high-power inverter was introduced, serving as a core building block for industrial, solar, and wind applications.
  • 2006
    • ABB launched the ACS350 and ACSM1 machinery drives, spanning from entry-level to high-performance servo control.
2010's

Development of unified platforms and high-speed application capabilities accelerated.

  • 2011
    • ABB introduced the All-Compatible platform for low- and medium-voltage drives, featuring unified architecture, common connectivity, cloud services, and mobile device support.
  • 2013
    • The All-Compatible ACS880 product family was launched.
  • 2016
    • ABB introduced a mobile drive module for fully electric and hybrid working machines.
  • 2017
    • ABB released the ACS580 general-purpose drive and the ACH580 for HVACR applications.
    • ABB developed a subsea variable speed drive.
  • 2018
    • The ACQ580, a US NEMA-rated drive for water and wastewater applications, was released.
2020's

ABB continues to address the global shift toward electrification and digitalization.

  • 2021-2024
    • ABB launched new control units for industrial drives, offering integrated connectivity, remote/cloud access, AI-driven analytics, and increased computing power.
  • 2025
    • Focus on developing lifecycle services for Finnish-made ABB drives and expanding global service channels.
What's next?
  • 2025 and beyond
    • ABB will focus on the future of electricity production, usage, and storage through improved power quality, power density, energy efficiency, and cooling technologies.
    • Artificial intelligence will offer transformative opportunities for drive control, diagnostics, energy management, and customer applications.
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