CLOSED-LOOP SYSTEM STEP RESPONSE

a) Small - signals analysis.

The transfer function (3) can be written as follows:

) =

0.044

1

+

s

2

ξ

1

+

2

(7)

where wo =

√

is the cutoff frequency

ξ =

√

is the dumping factor

By choosing the

ξ value, it is possible to determine

the system response to an input step signal.

Examples :

1)

ξ = 1 from which

(t)

=

0.044

[ 1

− e

−

t

t

(where Vi is the amplitude of the input step).

2)

ξ =

1

√ 2

from which

(t) =

0.044

(1 − cos

t

e

−

t

Fi gure 8. Small S ignal Step Response

(normalized amplitude vs.

t = 100

µs/div.

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