SAT – Saturation with variable limits

Block SymbolLicensing group: STANDARD

Function Description
The SAT block copies the input u to the output y if the input signal satisfies $lolim \leq u$ and $u \leq hilim$ , where lolim and hilim are state variables of the block. If $u < lolim$ ( $u > hilim$ ), then $y = lolim$ ( $y = hilim$ ). The upper and lower limits are either constants ( $HLD = on$ ) defined by parameters hilim0 and lolim0 respectively or input-driven variables ( $HLD = off$ , hi and lo inputs). The maximal rate at which the active limits may vary is given by time constants tp (positive slope) and tn (negative slope). These rates are active even if the saturation limits are changed manually ( $HLD = on$ ) using the hilim0 and lolim0 parameters. To allow immediate changes of the saturation limits, set $tp = 0$ and $tn = 0$ . The HL and LL outputs indicate the upper and lower saturation respectively.

If necessary, the hilim0 and lolim0 parameters are used as initial values for the input-driven saturation limits.

Inputs

u	Analog input of the block	Double (F64)
hi	Upper limit of the output signal (for the case $HLD = off$ )	Double (F64)
lo	Lower limit of the output signal (for the case $HLD = off$ )	Double (F64)

Outputs

y	Analog output of the block	Double (F64)
HL	Upper limit saturation indicator	Bool
LL	Lower limit saturation indicator	Bool

Parameters

tp	Time constant defining the maximal positive slope of active limit changes $⊙$ 1.0	Double (F64)
tn	Time constant defining the maximum negative slope of active limit changes $⊙$ 1.0	Double (F64)
hilim0	Upper limit of the output (valid for $HLD = on$ ) $⊙$ 1.0	Double (F64)
lolim0	Lower limit of the output (valid for $HLD = on$ ) $⊙$ -1.0	Double (F64)
HLD	Fixed saturation limits $⊙$ on	Bool
	off .. Variable limits on ... Fixed limits

[Previous] [Back to top] [Up] [Next]