Key facts
- Brand
- STMicroelectronics
- Model
- ST7FMC
- Documents
- 2
- Languages
- EN
- Last added
- 2012-08-07
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STMicroelectronics ST7FMC Enhanced Sensorless Startup Control Application Note AN2502
The document details how the ST7FMC microcontroller controls 3-phase brushless DC (BLDC) motors in position sensorless mode. It highlights a specific capability to monitor zero crossings of all three back EMF voltages directly without attenuation, allowing for startup from zero speed without the need for initial rotor stepping.
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How to use the product for one specific task, with worked examples.
Questions answered in these manuals
What voltage is the BLDC motor tested on in this application note?
The concept was implemented using a starter kit to run an onboard 24V Ametek BLDC motor.
From: STMicroelectronics ST7FMC Enhanced Sensorless Startup Control Application Note AN2502
What is the minimum voltage level mentioned for which this method will be even more reliable?
The document states that for higher voltage motors, such as 300V DC, this method will be even more reliable.
From: STMicroelectronics ST7FMC Enhanced Sensorless Startup Control Application Note AN2502
What are the advantages of controlling a PMSM as an AC motor instead of a BLDC motor?
Controlling a PMSM as an AC motor results in sinusoidal currents which produce lower audible noise, lower core losses, and allow for optimized power circuit dimensioning compared to rectangular currents.
How does the ST7FMC estimate rotor speed with Hall sensors?
The microcontroller calculates rotor speed based on the time difference between two consecutive Hall sensor edges, which corresponds to a specific electrical angle (e.g., 60 degrees for three sensors).