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 maximum rate at which the active limits may vary is given by parameters tp and tn as follows:

the steepest rise per second: $1 ∕ t p$ ,
the steepest descent per second: $- 1 ∕ t n$ .

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.

This block propagates the signal quality. More information can be found in the 1.4 section.

Input

u	Analog input of the block	Double (F64)
hi	Upper limit of the output signal	Double (F64)
lo	Lower limit of the output signal	Double (F64)

Parameter

tp	Slope limiter for positive limits change [s] $⊙$ 1.0	Double (F64)
tn	Slope limiter for negative limits change [s] $⊙$ 1.0	Double (F64)
hilim0	Upper limit of the output (valid when HLD=1) $⊙$ 1.0	Double (F64)
lolim0	Lower limit of the output (valid when HLD=1) $⊙$ -1.0	Double (F64)
HLD	Fixed saturation limits $⊙$ on	Bool
	off .. Variable saturation limits on ... Fixed saturation limits

Output

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

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