ABB ACS880-01-430A-3+N5350 - Page 144

Startup Assistant & Parameters 12-653AXD50000011888
Table 12-4 Level 1 Parameter Block Definitions
Block Title
Parameter (Number)
Selection (Value)
Descriptions
SPEED CONTROL
(Continued)
SPEED INTEGRATION TIME
(25.03)
Default: 4.00s
Range: 0.00 to 1000.00s
Denes the integration time of the speed controller. The integration
time denes the rate at which the controller output changes when
the error value is constant and the proportional gain of the speed
controller is 1. The shorter the integration time, the faster the
continuous error value is corrected. This time constant must be set to
the same order of magnitude as the time constant (time to respond)
of the actual mechanical system being controlled, otherwise instability
will result.Setting the integration time to zero disables the I-part of
the controller. This is useful to do when tuning the proportional gain;
adjust the proportional gain rst, then return the integration time.Anti-
windup (the integrator just integrates up to 100%) stops the integrator
if the controller output is limited.The gure below shows the speed
controller output after an error step when the error remains constant.
K
p
× e
K
p
× e
%
e = Error value
Time
Gain = K
p
= 1
T
I
= Integration time > 0
T
D
= Derivation time = 0
Controller output
T
I
SPEED DERIVATION TIME
(25.04)
Default: 0.000s
Range: 0.000 to 1000.00s
Denes the derivation time of the speed controller. Derivative action
boosts the controller output if the error value changes. The longer the
derivation time, the more the speed controller output is boosted during
the change. If the derivation time is set to zero, the controller works as
a PI controller, otherwise as a PID controller. The derivation makes the
control more responsive for disturbances. For simple applications
(especially those without a pulse encoder), derivative time is not normally
required and should be left at zero. The speed error derivative must be
ltered with a low pass lter to eliminate disturbances. The gure below
shows the speed controller output after an error step when the error
remains constant.