nuDrive Accessory User Guide
20
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Use the following formula to calculate the value for R42, which determines
the peak current limit:
where R42 represents the resistor value in k
Ω
and I
peak
represents the
maximum allowable peak current for the motor.
Use the following formula to calculate the value for R40, which determines
the continuous current limit:
where R40 represents the resistor value in k
Ω
and I
cont
represents the
maximum allowable continuos current for the motor.
Table 3 lists the factory default values for the current gain and current limits
resistors.
Note
The 47.5 k
Ω
value for R6 and R7 actually corresponds to a maximum output current
of 10.5 A rather than 10 A (although the actual output current will never exceed the 10 A
configured by R42). This is because 47.5 k
Ω
is the closest standard resistor value below
the 50 k
Ω
value that would correspond to a gain of 1.0 and, therefore, a maximum output
current of 10 A. Use the closest resistor value below the value you calculate for R40 and
R42 to ensure that your current limits do not exceed your motor’s specifications. Use the
closest resistor value below the value you calculate for R6 and R7 to ensure that your gain
value provides a maximum current output that matches or exceeds your peak current
setting (the drive will not actually output current that exceeds the peak current setting).
As an example, if you used a maximum input command voltage value of
±10 V, and you wanted to set your peak current limit to 6.4 A and your
continuous current limit to 2.7 A, you would calculate your resistor values
as demonstrated in the following example.
Table 3.
Default Current Gain and Current Limit Resistor Values
Resistor
Value
Description
R6
47.5 k
Ω
Current gain of 1.1 A/V
R7
47.5 k
Ω
Current gain of 1.1 A/V
R40
3.3 k
Ω
Continuous current limit of 5 A
R42
10 k
Ω
Peak current limit of 10 A
R42
10
I
peak
×
20
I
peak
–
-----------------------
=
R40
2
I
cont
×
8
I
cont
–
-------------------
=
Summary of Contents for nuDrive 2CF-001
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