AnsweredAssumed Answered

L6629 Speed/Torque control

Question asked by ignas.g on Feb 27, 2015
Latest reply on Apr 8, 2015 by Enrico Poli
Hello,
I'm trying to control 12V BLDC motor with 3 x 120° Hall sensors, using L6229PD eval board from ST.
I'm controlling Speed by connecting 5V PWM signal (0-255) from microprocessor to FRW/REW pin (28) on CN4 connector. Visually everything seems OK - 0 one direction max speed, slowing down to zero when PWM comes close to mid point (128), and then reversing direction to maximum speed when reaching 255.
BUT. Motor very quickly looses torque when speed starts to decrease. On 70-180 PWM values it is unusable for my application.
How can I have high enough torque when decreasing speed ? Or how to control speed to not to loose the torque so drastically ?
 

P.S. Onboard Speed/Torque switch - can't find any differences in those two modes.

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