AN1905 ST Microelectronics, Inc., AN1905 Datasheet - Page 18

• Manufacturer Part Number: AN1905
• Description: St7mc Three-phase BLDC Motor Control Software Library
• Manufacturer: ST Microelectronics, Inc.

ST7MC THREE-PHASE BLDC MOTOR CONTROL SOFTWARE LIBRARY
3.3 STANDALONE MODE AND CLOSED LOOP OPERATION
To run a BLDC motor in standalone closed loop, the approach should be, for a given target
mechanical speed, to fine tune all the realtime parameters most adequate for this speed. For
each target speed, these values should be recorded in the form of a table, which will be used
by the ST7MC standalone firmware. You should collect data for 4 speeds: the min and max
speeds specified in the GUI advanced screen, and 2 intermediate speeds of your choice. The
ST7MC standalone firmware will then make a linear extrapolation of realtime parameters in
between the 4 specified speeds to ensure smooth operation.
Once the data is collected, edit the ‘mtc.h’ file and fill in the field dedicated to the Rising/Falling
Bemf, Ki, Kp coefficient calculation (see
Figure 6. ‘mtc.h’ field for coefficient computation
Once the motor runs, rising/falling Back-EMF and proportional/integer coefficients are com-
puted following a linear curve between F_min and F_1, F_1 and F_2, F_2 and F_max (see
Figure
(for example F_1 = 1234 means F_1 = 123.4Hz).
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// See 'Mtc_Settings_Sensorless.h' for Freq_Min & Freq_Max values
//Fmin
#define Rising_Fmin
#define Falling_Fmin
#define Ki_Fmin
#define Kp_Fmin
//F_1
#define F_1
#define Rising_F_1
#define Falling_F_1
#define Ki_F_1
#define Kp_F_1
//F_2
#define F_2
#define Rising_F_2
#define Falling_F_2
#define Ki_F_2
#define Kp_F_2
//Fmax
#define Rising_Fmax
#define Falling_Fmax
#define Ki_Fmax
#define Kp_Fmax
7). Note that F_min, F_1, F_2, F_max are electrical frequencies, with 0.1 Hz resolution
30
16
20
10
30
50
40
20
10
30
10
50
40
10
13
18
1000
2000
// Frequency min coefficient settings
// 100 Hz
// Intermediate frequency 1 coefficient settings
// 200 Hz
// Intermediate frequency 2 coefficient settings
// Frequency max coefficient settings
Figure
6).