Board description
UM1036
20/48
Doc ID 18293 Rev 1
With the default values this gives:
●
V
BIAS
= 1.57 V
●
Maximal voltage of V
SIGN
= 1.56 V
●
G = 5.38
●
G
TOT
= 3.90
●
Maximum current amplifiable without distortion is 16 A.
Figure 11.
Configuration for FOC
Table 1
shows the mentioned setting of gain jumpers for both FOC configurations.
Six-step (block commutation) current reading configuration
In the case of six-step (also called block commutation) current control, only two of the motor
phases conduct current at the same time. Therefore, it is possible to use only one shunt
resistor placed on the DC link to measure the motor phase current. Furthermore, as the
current is always flowing in the same direction on the shunt resistor, only positive current
must be measured, and in this case the amplifying network needs to be properly designed.
The details of single-shunt current sensing reading configuration are shown in
Figure 12
. In
this configuration, the current sampling is done only when the value on the shunt resistor is
positive. Only the positive value read on the shunt resistor allows the setting of a higher gain
for the op amp than the one set in three-shunt reading mode.
436
/0/54
/0
/0
'.$
6
2 222
2222
R 222
2 222
R 222
2(3
SENSE
RESISTOR
2,3
SENSE
RESISTOR
6
/0!-0
22
22
!-
Table 1.
Gain settings for FOC current reading configuration
Setting for FOC configuration
Three-shunt configuration
Single-shunt configuration
Setting of gain
W11
Present
W11
Present
W12
Present
W12
Present
W13
Present
W13
Present
W14
Present
W14
Present
