SAT – Saturation with variable limits

Block SymbolLicensing group: STANDARD
PIC

Function Description
The SAT block copies the input u to the output y if the input signal satisfies lolim u and uhilim, 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

hi

Upper limit of the output signal (for the case HLD = off)

double

lo

Lower limit of the output signal (for the case HLD = off)

double

Outputs

y

Analog output of the block

double

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

tn

Time constant defining the maximum negative slope of active limit changes  1.0

double

hilim0

Upper limit of the output (valid for HLD = on)  1.0

double

lolim0

Lower limit of the output (valid for HLD = on)  -1.0

double

HLD

Fixed saturation limits  on

bool

off ..

Variable limits

on ...

Fixed limits

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