User manual

TMCM-1640 TMCL Firmware V2.00 Manual (Rev. 2.00 / 2012-JUL-31) 50
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7.2 Current Regulation
The current regulation mode uses a PID regulator to adjust a desired motor current. This target current can
be set by axis parameter 155. The maximal target current is limited by axis parameter 6.
The PID regulation uses three basic parameters: The P and I value as well as the timing control value.
TIMING CONTROL VALUE
The timing control value (current regulation loop multiplier, axis parameter 134) determines how often the
current regulation is invoked. It is given in multiple of 50µs:


 

 


= resulting delay between two current regulation loops


= current regulation loop multiplier parameter
For most applications it is recommended to leave this parameter unchanged at its default of 2*50µs. Higher
values may be necessary for very slow and less dynamic drives.
STRUCTURE OF THE CURRENT REGULATOR
I
ACTUAL
˗
I
TARGET
+
P
PARAM
/256
X
I
PARAM
/65536
X
+
Clip
-32768..
+32767
SVPWM
Clip
I
Max
Clip
I
CLIP
e
SUM
Figure 7.2: Current regulation
Parameter
Description
I
ACTUAL
Actual motor current (GAP 150)
I
TARGET
Target motor current (SAP 155)
I
Max
Max. motor current (SAP 6)
e
SUM
Error sum for integral calculation (GAP 201)
P
PARAM
Current P parameter (SAP 172)
I
PARAM
Current I parameter (SAP 173)
PARAMETERIZING THE CURRENT REGULATOR SET
1. Set the P parameter and the I parameter to zero.
2. Start the motor by using a low target current (e.g. 1000 mA).
3. Modify the current P parameter. Start from a low value and go to a higher value, until the actual
current nearly reaches 50% of the desired target current.
4. Do the same with the current I parameter.
For all tests set the motor current limitation to a realistic value, so that your power supply does not become
overloaded during acceleration phases. If your power supply reaches current limitation, the unit may reset or
undetermined regulation results may occur.