The story began at Strömberg in Helsinki (a company that later became part of ABB). The innovation that made it all possible is called pulse-width modulation (PWM). That is the concept of using voltage pulses to synthesize any required voltage and frequency. PWM, in turn, was made possible through progress in power semiconductors - compact devices that switch voltage on and off at high frequency, with great precision and at low losses - and all this without moving parts. 

The invention was the work of Martti “Roope” Harmoinen and his team. The first drive design, called the SAMI A, was rated at 350 kVA/500 V. Not long after, drives were fitted to trains of Helsinki’s metro. The passengers were treated to smoother acceleration while the company benefitted from lower energy consumption.

Harmoinen’s pioneering role was later recognized with the Finnish Engineering Award (1981) and an honorary professorship (1995). Harmoinen passed away in 2023 at the age of 88.

Performance, savings and a better planet

The payoffs of drives are twofold: On average, electricity usage is reduced by 30%, but can reach as much as 80% in variable‑torque duties. The advantages do not stop there: Smoother starting and control mean lower thermal and mechanical stress on the motors as well as on the belts, pumps and other connected equipment. This extends asset life and reduces unplanned downtime. Softer starts and greater controllability are also good news for the product being handled. For example, it avoids unwanted foaming of liquids and the resulting waste.

Motors consume roughly 45% of global electricity, yet fewer than 25% are presently paired with drives - demonstrating a huge efficiency reserve still to be harvested. In Europe alone, broader adoption on pumps, fans, and compressors could abate about 140 TWh annually, in addition to the estimated 41 TWh/year already being saved today. These reductions equate to about 38 million tons of CO₂ avoided.

Digital and secure

Today’s LV VSDs do far more than simply power motors. They integrate powerful microprocessors that can run numerous functions ranging from toolboxes for setup and configuration to the analysis of waveforms, permitting insights into the operations of both the motors and the connected equipment. This can be harvested for optimization and maintenance.

Tools such as Crealizer™ allow customers to unlock additional information and functionality by optimizing drives to their own particular needs and situations.

As connectivity grows, “secure by design” becomes mandatory: contemporary drives (e.g., ACS380‑E) embed measures such as port hardening, secure boot/code verification, and compliance with IEC 62443‑4‑2 to protect integrity and uptime within industrial networks. 

Grid friendliness

One challenge that can be associated with drives is electrical harmonics. These are current and voltage distortions due to switching inside the drives that – if present in an excessive amount and not managed properly – can cause malfunctions and excess heating of power network equipment. Ultra‑Low Harmonic (ULH) drives address this challenge by minimizing total harmonic distortion. This improves both equipment performance and power quality, eliminating costly mitigation hardware. Examples include the heat‑pump systems supplying ~19,300 MWh of carbon‑neutral heat annually at Orion’s pharmaceutical facilities in Finland.

Variable speed drives at 50

Drives today are a central part of the fight for energy efficiency, helping industries outrun, leaner and cleaner.