TMC4671 Datasheet • IC Version V1.00 | Document Revision V1.04 • 2018-Dec-11
21 / 157
Hexadecimal Value
0x5A81h
u16
23169
32767
s16
23169
32767
q8.8
23169 / 256
32767 / 256
q4.12
23169 / 4096
32767 / 4096
0x7FFFh
0x8000h
32768 -32768 -32768 / 256 -32768 / 4096
32769 -32767 -32767 / 256 -32767 / 4096
32770 -32766 -32766 / 256 -32766 / 4096
49153 -16383 -16383 / 256 -16383 / 4096
0x8001h
0x8002h
0xC001h
0xFFFEh
65534
65535
-2
-1
-2 / 256
-1 / 256
-2 / 4096
-1 / 4096
0xFFFFh
Table 5: Examples of u16, s16, q8.8, q4.12
The q8.8 and q4.12 are used for P and I parameters which are positive numbers. Note that q8.8 and q4.12
are used as signed numbers. This is because theses values are multiplied with signed error values resp.
error integral values.
4.3.2 N_POLE_PAIRS, PHI_E, PHI_M
The parameter N_POLE_PAIRS defines the factor between electrical angle PHI_E and mechanical angle
PHI_M of a motor (pls. refer figure 12).
A motor with one (1) pole pair turns once for each electrical period. A motor with two (2) pole pairs turns
once for every two electrical periods. A motor with three (3) pole pairs turns once for every three electrical
periods. A motor with four pole (4) pairs turns once for every four electrical periods.
The electrical angle PHI_E is relevant for the commutation of the motor. It is relevant for the torque control
of the inner FOC loop.
PHI_E = PHI_M · N_POLE_PAIRS
(3)
The mechanical angle PHI_M is primarily relevant for velocity control and for positioning. This is because
one wants to control the motor speed in terms of mechanical turns and not in terms of electrical turns.
PHI_M = PHI_E/N_POLE_PAIRS
(4)
Different encoders give different kinds of position angles. Digital Hall sensors normally give the electrical
position PHI_E that can be used for commutation. Analog encoders give - depending on their resolu-
tion - angles that have to be scaled first to mechanical angles PHI_M and to electrical angles PHI_E for
commutation.
©2018 TRINAMIC Motion Control GmbH & Co. KG, Hamburg, Germany
Terms of delivery and rights to technical change reserved.
Download newest version at www.trinamic.com
TRINAMIC [ TRINAMIC MOTION CONTROL GMBH & CO. KG. ]
