TMC4671 Datasheet • IC Version V1.00 | Document Revision V1.04 • 2018-Dec-11
32 / 157
ADC_GAIN
=
(
(
I_SENSE_MAX ∗ R_SENSE
SENSE_AMPLIFIER_GAIN
)
)
(12)
∗
∗
ADC_RAW_MAX/ADC_U_MAX
Rsense [mΩ] Isense [A] Usense [mV ] GAIN[V/V ] ADC_GAIN[A/V ] Sense Amplifier
5
10
5
50
50
20
20
10
5
AD8204
AD8204
10
Table 15: Example Parameters for ADC_GAIN
For the FOC, the ADC_RAW is scaled by the ADC scaler of the TMC4671 together with subtraction of offset
to compensate it. Internally, the TMC4671 FOC engine calculates with s16 values. So, the ADC scaling needs
to be chosen so that the measured currents fit into the s16 range. With the ADC scaler, the user can choose
a scaling with physical units like [mA]. A scaling to [mA] covers a current range of
] resolution. For higher currents, the user can choose unusual units like centi Ampere [cA] covering
−327A . . . + 327A or deci Ampere −3276A . . . + 3276A.
−
32A . . . + 32
A
with
m[A
ADC scaler and offset compensators are for mapping raw ADC values to s16 scaled and offset cleaned
current measurement values that are adequate for the FOC.
4.6.1 FOC3 - Stator Coil Currents I_U, I_V, I_W and Association to Terminal Voltages U_U, U_V, U_W
The correct association between stator terminal voltages U_U, U_V, U_W and stator coil currents I_U, I_V,
I_W is essential for the FOC.
For three-phase motors with three terminals U, V, W, the voltage U_U is in phase with the current I_U, U_V
is in phase with I_V, and U_W is in phase with I_W according to equations (13) and (14) for FOC3.
UU (φe) = UD
UV (φe) = UD
UW (φe) = UD
·
·
·
sin(φe)
sin(φe + 120o)
sin(φe − 120o)
U_UVW_FOC3(U_D, PHI_E)
I_UVW_FOC3(I_D, PHI_E)
=
(13)
(14)
IU (φe) = ID
IV (φe) = ID
IW (φe) = ID
·
·
·
sin(φe)
sin(φe + 120o)
sin(φe − 120o)
=
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