YASKAWA E7U Programming Manual page 63

Setting: 30
By configuring one of the digital inputs as an Integral Reset Input, (H1-0x= 30), the value of the integral component of PI
control can be reset to zero whenever the configured input is CLOSED. The integral component of PI control will be held at
zero as long as the configured digital input is held CLOSED.
Resetting the Integral component of PI control can be useful in cases where an excessively large Integral value prevents the PI
control from responding quickly to changes in the system being regulated by the Drive (e.g. duct pressure, water temperature).
Function: PI Integral Hold
Setting: 31
By configuring a digital input as an Integral Hold input (H1-0X= 31), the value of the Integral component of the PI control can
be forced to clamp at the value it was at when the input is CLOSED. The Integral component of the PI control returns to
accumulating error when the digital input is OPEN again.
Holding the Integral Value can be useful during periods when the error can build up naturally, such as during long
accelerations. Not allowing Integral windup produces a more stable PI control.
Function: PI SFS Cancel
Setting: 34
SFS means softstart, also referred to as accel/decel in this description.
By configuring a digital input as a PI SFS (softstart) Cancel input (H1-0x= 34), the operator will be able to use a contact closure
to remove the acceleration and deceleration times that are applied to changes in the PI setpoint by the b5-17 parameter. If the
digital input configured as PI SFS Cancel is closed, the PI setpoint Accel/Decel (Parameter b5-17) will be ignored. Immediate
updating of any change to the setpoint will apply.
Function: Input Level Sel
Setting: 35
When using the PI Function built into the Drive, the chosen set point is compared with the measured feedback. The difference
is called the Error. The proportional and integral function are applied to this error. For some applications it may be appropriate
to invert the input to the PI block . This can be accomplished by setting one of the digital inputs up as an Input Level Sel
(H1-0x=35). When an Input Level Sel digital input is closed the Error will be inverted before it is passed to the PI block.
Set
+
Point
-
Feed
back
Fig. 39 PI Error signal Inversion Block Diagram
Programming 57
H1=0x=35
Open
OP
PI Block
-1
Z
Closed
CLOSED