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STM8S BLDC Speed Closed Loop runaway issue

Question asked by sangani.sam on Aug 19, 2013
Latest reply on Aug 26, 2013 by Gigi
Hi,
I am using STM8S three-phase BLDC motor control software library V1.0 to drive BLDC. Everything works great except PI regulator for speed closed loop runways after speed 13000rpm.

My settings are:

#define PWM_FREQUENCY 14400

#define SPEED_KP 40 
#define SPEED_KI 0.01

#define SPEED_OUT_MAX 666
#define SPEED_KP_DIVISOR 128
#define SPEED_KI_DIVISOR 512

#define SPEED_PID_SAMPLING_TIME 4

#define HALL_MAX_SPEED_01HZ          ((u16)4333)
#define MOTOR_POLE_PAIRS 2
#define MAX_SPEED_RPM 16000

I have checked there is no overflow of PI regulator registers. After 13000rpm, motor speed ramps up rapidly and keeps going on until is stopped. To be safe I stopped motor at 20000rpm.

It will be highly appreciated if some one aware of this issue or can think of potential root cause and guide me to solution.

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