The feedback value of back-emf used for the field weakening control, when BEMF SOURCE is set to BEMF INPUT. It allows for the use of the field
weakening control structure on motors not directly connected to the armature terminals. It can be wired within the block diagram to an analogue input
or a communications path.
The use of this parameter is typically combined with parameters ISOL DMD SOURCE and 3-PHASE FIELD (CURRENT LOOP function block) to
apply the drive to field weakening control of a motor field.
Note: If the ADVANCED field weakening mode is being used with an external back-emf feedback, ensure to apply the speed feedback so that
the base speed calculator can function correctly.
Action of EMULATE 590P on Software Versions
In 590+ software version 5.x or earlier, the processor was using a 12MHz clock. The formulae used to compute internal
variables from the "visible" time constant (set by DSElite or MMI) were dependant on that crystal frequency.
Software version 7.x introduced a 16MHz crystal, but the formulae were not changed. Thus, a 12/16 factor was added in
error to the time constant for the following parameters in the FIELD CONTROL function block:
EMF LEAD (tag 175)
EMF LAG (tag 176)
BEMF FBK LEAD (tag 191)
BEMF FBK LAG (tag 192)
Software version 8.x corrects this error, and also includes the EMULATE 590P parameter in the Configure Drive function block. When EMULATE
590P is set to non-zero, the drive emulates the features of software version 7.x, including the (INCORRECT) 12/16 factor. See the table below.
Software Version
EMULATE 590P
Non-zero (emulating) Zero
5.x CORRECT 200ms = 200ms Not applicable
7.x INCORRECT 200ms = 150ms Not applicable
8.x INCORRECT 200ms = 150ms CORRECT 200ms = 200ms
To Next Page
Loading...
