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Daniel_P
Visitor II
July 1, 2024

Industry-first embedded software for sensorless zero-speed/high-torque motor control

  • July 1, 2024
  • 2 replies
  • 1935 views

The ZeST software algorithm for STM32 allows sensorless motor drives to achieve full torque at zero speed. This innovation enables smooth and predictable motor control in general-purpose drives.     

Applications such as power tools, domestic appliances, and e-bikes require motors that can start quickly and with maximum torque. Traditional sensorless drives are unable to meet these demands as they cannot detect rotor position when stationary. The STM32 ZeST algorithm offers a solution that enables optimal sensorless control for any permanent magnet synchronous motor (PMSM) at zero speed, working in conjunction with the high-sensitivity observer (HSO) algorithm. This embedded software solution operates seamlessly without the need for extra hardware or special features in the microcontroller, and it dynamically estimates motor resistance for efficient control.

The STM32 ZeST and HSO algorithms not only improve energy efficiency by reducing peak current during startup but also lower the bill of materials and enhance reliability, offering an advantage over sensor-equipped drives. ST has showcased this technology with a model that demonstrates the motor's ability to start and maintain a load at various speeds, including a complete standstill, while always starting in the correct direction.

ST32239_STEVAL-LVLP01_persp_scr.jpgST27802_B-G473E-ZEST1S-perspective2_scr.jpg

 

 

 

 

To support development, ST provides the B-G473E-ZEST1S control board and the STEVAL-LVLP01 power board, designed for low-power motors like those in the B-MOTOR-PMSMA kit, using a new motor-control connector.

The STM32 microcontroller family is supported by the ST motor control software development kit (MC-SDK), which includes a firmware library and the motor control workbench for configuration, both part of the STM32Cube ecosystem. The HSO algorithm is available in the latest MCSDK update (version 6.2) which also introduces a dual-drive solution for STM32G4 MCUs and extends support to the entire STM32 range, catering to various performance and cost requirements.

First published on Dec 13, 2023

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      2 replies

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      darenluie
      Graduate
      December 28, 2025

      The ZeST and HSO algorithms for STM32 make sensorless motor control at zero speed much more reliable. This kind of precise motor control can be really useful in practical applications, like automated home systems or smart devices, where smooth and efficient operation is important. Using these microcontrollers helps create efficient and dependable solutions even in cost-sensitive projects.

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      Wjr
      Visitor II
      December 28, 2025
      Your information is incorrect. More then 20 years ago i have invented a (uniform) motor control method that allows to control a motor at any speed and load condition - the implementation is very simple , cost effective and highly efficient. It was also implemented in an ELMOS IC 981.15, but there are also numerous SW-implementations in industrial applications. With a suitably designed motor the resolution can be very high and turns this motor into a lowcost servo.
      If You are interested in more information, please let me know.
      Best regards
      Dr. Rolf Strothmann

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