Emerson Mentor MP User Manual

Parameter
description
protocol
Performance
Menu
3
This
is
the
final
speed
demand
at
the
input
to
the
speed
regulator
formed
by
the
sum
of
the
ramp
output
and
the
hard
speed
reference
(if
the
hard
The
speed
feedback
can
be
taken
from
the
drive
encoder
port
or
tachometer
or
armature
voltage
or
a
position
feedback
module
installed
in
any
slot
Where
ELPR
is
the
equivalent
encoder
lines
per
revolution
as
defined
below:
For
example
a
4096
line
Ab
type
encoder
gives
a
ripple
level
of
0.23
rpm.
Parameter
structure
Keypad and
format
Advanced parameter
descriptions
Serial comms
speed reference is enabled). If the drive is disabled this parameter will show 0.0.
as selected with Pr 3.26 { Fb01, 0.71 }. Pr 3.02 { di05, 0.40 } shows the level of the speed feedback selected for the speed controller. Display filtering is
active when this parameter is viewed with one of the drive keypads. The value held in the drive parameter (accessible via comms or an Solutions
Module) does not include this filter, but is a value that is obtained over a sliding 16 ms period to limit the ripple seen in this parameter value. The
speed feedback value includes encoder quantization ripple given by the following equation:
Ripple in Pr 3.02 { Fb01, 0.71 } = 60 / 16 ms / (ELPR x 4)
The 16 ms sliding window filter is always applied to the value shown in Pr 3.02 {Fb01, 0.71}, but this sliding window filter is not normally
applied to the actual speed feedback used by the speed controller or the drive encoder reference system (Pr 3.43 to Pr 3.46). The user may
apply a filter to the speed controller input and the drive encoder reference system input if required by setting Pr 3.42 to the required filter time. The
encoder ripple seen by the speed controller is given by:
Encoder speed ripple = 60 / Filter time / (ELPR x 4)
If Pr 3.42 is set to zero (no filter) the ripple seen by the speed controller and drive encoder reference system is given by:
Encoder speed ripple = 60 / 250 µs / (ELPR x 4)
From the drive
encoder port
Filter
defined
by Pr 3.42
16ms
filter
Speed
controller
Drive encoder
reference
system
Pr 3.02 and
Pr 3.27
The diagram above shows the filter arrangement. It should be noted that the same filtering is provided at the speed controller input and for Pr 3.02
{ di05, 0.40 } when the feedback is obtained from an Solutions Module, but the variable length window filter is controlled by Pr x.19 .
It is not advisable to set the speed feedback filter too high unless it is specifically required for high inertia applications with high controller gains
because the filter has a non-linear transfer function. It is preferable to use the current demand filters (see Pr 4.12 or Pr 4.23 ) as these are linear first
order filters that provide filtering on noise generated from both the speed reference and the speed feedback. It should be noted that any filtering
included within the speed controller feedback loop, either on the speed feedback or the current demand, introduces a delay and limits the maximum
bandwidth of the controller for stable operation.
Mentor MP Advanced User Guide 43
Issue Number: 4 www.onxcontrol.com
3.01
{di04, 0.39}
Final speed reference
Coding
Bit
SP
FI
DE
Txt
VM
DP
ND
RA
NC
NV
PT
US
RW
BU
PS
1
1
1
1
1
1
Range
±SPEED_MAX rpm
Update rate
4 ms write
3.02
{di05, 0.40}
Speed feedback
Coding
Bit
SP
FI
DE
Txt
VM
DP
ND
RA
NC
NV
PT
US
RW
BU
PS
1
1
1
1
1
1
Range
±SPEED_MAX rpm
Update rate
4 ms write
Position feedback device
ELPR
Ab
number
of
lines
per
revolution
Fd,
Fr
number
of
lines
per
revolution
/
2

Emerson Mentor MP Specifications

General

Brand	Emerson
Model	Mentor MP
Category	DC Drives
Language	English