Current Trimming Mode; Menu 4: Current Control; Regen Mode - Emerson SP1201 Installation Manual

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Introduction
Information information
Power feed-forward compensation
3.10
Drive mode Regen
Bit SP
Coding
Range Regen
Default Regen
Update rate 4ms
Power feed-forward compensation can be used to reduce the transient DC bus voltage produced when a fast load transient occurs on drives
connected to the Regen drive. 100.0% power feed-forward is equivalent to an active current of Rated drive current / 0.45 (i.e. over current trip level)
and an AC terminal peak phase voltage equal to DC_VOLTAGE_MAX / 2. This scaling is the same as the power output from Pr 5.03 when high speed
output mode is used (see section 9.7 Menu 7: Analogue I/O ). Therefore an analogue output of the drive supplying the load and analogue input 2 or 3
of the drive acting as the supply Regen drive can be connected together to give power feed-forward compensation without further scaling if the two
drives are of equal rating. If the ratings are different the analogue input scaling must be used to give the correct power feed-forwards, where the
scaling is given by:
Load drive Rated drive current / Regen drive rated drive current

Current trimming mode

3.11
Drive mode Regen
Bit SP
Coding
Range Regen
Default Regen
Update rate 4ms read
This parameter defines the strategy used for current trimming in regen mode. If Pr 3.11=0 then current trimming is only carried out once after power-
up. If Pr 3.11=1 current trimming is carried out after power-up and then before the drive runs each time it is enabled.
9.4

Menu 4: Current control

In Regen mode the drive operates in a reference frame that is aligned to the voltage at the drive terminals. Because the phase shift across the input
inductors is small, the reference frame is approximately aligned with the supply voltage. The maximum normal operating current is controlled by the
current limits.
DRIVE_CURRENT_MAX is used in calculating the maximum of some parameters and is fixed at 1.75 x rated drive current. The drive can operate up
to this level under normal conditions.
The relationship between the voltage and current for Regen mode operation is shown in the following vector diagram.

Regen mode

wLi
sy
vs = Regen unit
terminal voltage
Supply
voltage
i
s
Definitions:
i = Regen drive terminal voltage vector
s
vs = Regen drive current vector
CURRENT_LIMIT_MAX is used as the maximum for some parameters such as the user current limits. The maximum current limit is defined as
follows (with a maximum of 1000%):
CURRENT_LIMIT_MAX =
Where:
Regen drive rated current is given by Pr 5.07
100
System Mechanical
design installation
FI DE Txt VM DP ND
1 2
±100 %
0.00
FI DE Txt VM DP ND
0 to 1
0
Maximum current
------------------------------------------------------ - ×
100%
Motor rated current
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Parameters
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1
PS
1 1
Unidrive SP Regen Installation Guide
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