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Applying the brake as the frequency passes through zero
In Open-loop mode the torque produced may reduce as the frequency passes through zero. To prevent the load from falling during this period in a vertical application, it is possible to apply the brake
momentarily to hold the load. If
BC Brake Apply Through Zero Threshold
(12.051) = 0 then the brake is not applied when the frequency passes through zero unless
Reference On
(01.011) = 0.
If
BC Brake Apply Through Zero Threshold
(12.051) is non-zero then the brake is always applied when the modulus of frequency is less than
BC Brake Apply Through Zero Threshold
(12.051) even
if
Reference On
(01.011) = 1. This ensures that the brake is applied and then released as the frequency passes through zero.
BC Brake Apply Through Zero Threshold
(12.051) should be set to a
value that is lower than both
BC Brake Release Frequency
(12.044) and
BC Brake Apply Frequency
(12.045) so that it does not interfere with the control of the brake when starting and stopping.
Forced initial direction
If
BC Initial Direction
(12.050) = 0 then the brake controller operates as described above and the user reference is used to define the direction of operation. If
BC Initial Direction
(12.050) = 1 then
Force Reference Direction
(01.057) is used force the frequency reference to the positive modulus of the selected user reference until the end of the post-brake release period whatever the direction
of the user reference. This can be used for example to ensure that in a vertical application the motor will definitely hold the load at the point when the brake is released. The diagram below shows the
brake controller sequence when
BC Initial Direction
(12.050) = 1, but the user reference direction is reverse. It should be noted that
BC Initial Direction
(12.050) has no effect if
BC Brake Apply Through Zero Threshold
(12.051) is non-zero, and the user reference direction is always used as the initial direction, to prevent a condition where the brake would release then apply
repeatedly.
If
BC Initial Direction
(12.050) = 2 then
Force Reference Direction
(01.057) is used to force the frequency reference to minus the modulus of the user selected reference until the end of the post-brake
release period to ensure that the output frequency is negative during this period.
Parameter
12.041
BC Enable
Short description
Enables the brake control function
Mode
Open
‑
loop
Minimum
0
Maximum
3
Default
0
Units
Type
8 Bit User Save
Update Rate
Action on exit from edit and reset
Display Format
Standard
Decimal Places
0
Coding
RW, TE
Unidrive M200 Parameter Reference Guide
Issue: 01.05.00.10
199
Summary of Contents for unidrive m200
Page 1: ...Parameter Reference Guide Unidrive M200 Open loop Mode Issue 01 05 00 10 ...
Page 30: ...30 Unidrive M200 Parameter Reference Guide Issue 01 05 00 10 ...
Page 83: ...Enable logic Unidrive M200 Parameter Reference Guide Issue 01 05 00 10 83 ...
Page 125: ...Unidrive M200 Parameter Reference Guide Issue 01 05 00 10 125 ...
Page 145: ...Unidrive M200 Parameter Reference Guide Issue 01 05 00 10 145 ...
Page 204: ...204 Unidrive M200 Parameter Reference Guide Issue 01 05 00 10 ...