DMC1500 Datasheet, PDF (50/67 Pages) List of Unclassifed Manufacturers – versatile digital motor controller

Spectrum Digital, Inc
2.16 Phase Voltage
The phase voltages are measured from the top transistor with respect to Bus-. Each
phase is divided by a resistive divider consisting of 400K and 4.99k. This gives a
division of 81. Each channel also contains a filter with a cutoff frequency of 3.2Khz.
The gain of each channel can be adjusted between 1 and 10. In our example we will
assume a maximum voltage of 160 volts.
Op-amp voltage = Phase Voltage / 81
Op-amp voltage = 160V / 81
Op-amp voltage = 1.97 Volts
The next step is to calculate the gain. In our case we want the 1.97 volts to correspond
to 5.0 volts to the A/D. The gain would be:
Gain = A/D Volts / Op-amp Volts
Gain = 5.0 volts / 1.97 Volts
Gain = 2.6
To set the gain make sure there is 0 phase volts. To set phase U volts install jumper
JP10. Next measure the voltage on JP10 and adjust R17 for .5 volts. This sets a
reference voltage we will use to set the gain. The output voltage will be:
Vout = Ref x gain
Vout = .5v x 2.6
Vout = 1.3V
Now measure the voltage on JP24 pin 17 and adjust R11 for 1.3 volts. Repeat this
procedure for each of the phases.
Table 51: Phase Current Gain Adjust
Phase
U
V
W
Jumper
JP10
JP13
JP15
Adjust
R11
R15
R18
Measure on
JP24
Pin 17
Pin 19
Pin 21
Note: Make sure the jumper is removed after each adjustment
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