Voltage Set-Point; Voltage Controller Kp Gain - Emerson SP1201 Installation Manual

Safety Product
Introduction
Information information

Voltage set-point

3.05
Drive mode Regen
Bit SP
Coding
Range Regen
Default Regen
Update rate Background
The Regen drive will attempt to hold the DC bus at the level specified by this parameter. The DC bus voltage must always be higher than the peak of
the line to line supply voltage if the unit is to operate correctly. The default values can be used with most supplies giving a reasonable level of control
headroom. However, with higher voltage supplies the set-point must be raised.

Voltage controller Kp gain

3.06
Drive mode Regen
Bit SP
Coding
Range Regen
Default Regen
Update rate Background
When the drive is operated as a Regen drive it uses a DC bus voltage controller with inner current controllers as shown below.
Pr 3.05 DC
bus voltage
set point
-
DC bus
voltage
feedback
The gains of the voltage and current controllers affect the stability of the regen unit control system and incorrect gain settings can result in over-
voltage or over-current trips. In many applications the default gains given for the current controllers (Pr 4.13 and Pr 4.14) will be suitable, however, it
may be necessary for the user to change these if the inductance or resistance of the supply plus the regen inductors varies significantly from the
expected values.
Setting the current controller gains
The most critical parameter for stability is the current controller proportional gain (Pr 4.13). The required value for this is dependent on the Regen unit
input inductance. If the inductance of the supply is a significant proportion of the recommended regen inductor (i.e. 60/IDR mH per phase, where IDR
is equivalent to Kc), then the proportional gain may need to be increased. The supply inductance is likely to be negligible compared to the regen
inductor value with small drives, but is likely to be significant with larger drives.
The proportional gain Pr 4.13 should be adjusted as described below using the total inductance per phase. The current controller integral gain Pr 4.14
is not so critical, and in a majority of cases the default value is suitable. However, if it is necessary to adjust this parameter it should be set up as
described below using the supply resistance for one phase.
The proportional gain Kp (Pr 4.13) is the most critical value in controlling the performance of the current controllers. The value can be set by the user
so that
Kp = (L / T) x (I / V ) x (256 / 5)
fs fs
Where:
T is the sample time of the current controllers. The drive compensates for any change of sample time, and so it should be assumed that the sample
time is equivalent to the lowest sample rate of 167µs.
L is the total inductance per phase
is the peak full scale current feedback = Kc x √2 / 0.45. Where Kc is the current scaling for each size of drive.
I
fs
V is the maximum DC link voltage.
fs
Therefore:
Kp = (L / 167µs) x (Kc x √2 / 0.45 / V
Where:
K = [√2 / (0.45 x V x 167µs)] x (256 / 5)
fs
Unidrive SP Regen Installation Guide
Issue Number: 2
System Mechanical
design installation
FI DE Txt VM DP ND
1
0 to DC_VOLTAGE_SET_MAX V
200V rating drive: 350
400V rating drive: 700
575V rating drive: 835
690V rating drive: 1005
FI DE Txt VM DP ND
0 to 65,535
4,000
Voltage
controller
-
Current
feedback
) x (256 / 5) = K x L x Kc
fs
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