Siemens Servo Ventilator 300, Service Manual

Page: 15 / 131

Servo Ventilator 300/300A Introduction
E382 E380E 061 01 03 01 Siemens-Elema AB 15
1
Inspiratory feedback control system
The inspiratory feedback control system
uses cascade control with a number of
controllers and compensating elements.
Flow regulation
Inspiratory flow regulation occurs during
inspiration time in the modes Volume
Control and SIMV (Vol. Contr.) and during
expiration time in all modes.
When flow regulation is used, the
shadowed main forward path comprises the
following:
• The microprocessor module in the block
MODE CPU
in the main block
REFERENCE
&
TIMING
generates a
FLOW REF
. signal.
• The block
MIXER
, in the main block
INSPIRATORY CONTROL
, splits the
FLOW REF
.
signal into one
GAS FLOW REF
. signal for each
inspiratory valve (
AIR FLOW REF
. and
O
2
FLOW
REF
.). Each
GAS FLOW REF
. signal is used
(after a minor correction within ±5 %) as
DESIRED GAS FLOW VALUE
(reference variable).
•
ACTUAL GAS FLOW VALUE
is generated by
signal converters (
FLOW
) using signals from
measuring
TRANSDUCERS
.
• The actuating signal from the
FLOW PI
CONTROL
results in the
DESIRED POSITION VALUE
(reference variable) for the
POSITION PD
CONTROL
. The
POSITION SENSOR
at the
INSPIRATORY VALVE
generates a valve position
signal which is used as the
ACTUAL POSITION
VALUE
in the
POSITION PD CONTROL
.
• The actuating signal from the
POSITION PD
CONTROL
results in the
DESIRED CURRENT VALUE
(reference variable) for the
CURRENT CONTROL
&
CURRENT POWER
.
• The
ACTUAL CURRENT VALUE
is an internal
feedback signal used in the
CURRENT
CONTROL
block.
• The actuating signal from the output stage
of the
CURRENT CONTROL
&
CURRENT POWER
is a
voltage pulse train with pulse width
modulation used to actuate the
INSPIRATORY
VALVE SOLENOID
which generates a certain
opening of the
INSPIRATORY VALVE
.
Flow
regulation
POSITION
SENSOR
INSPIRATORY
VALVE
CONTROLLED SYSTEM
VALVE
SOLENOID
PRESSURE
TRANSDUCERS
FLOW
ACTUAL CURRENT VALUE
ACTUAL POSITION VALUE
ACTUAL
SUPPLY
PRESS.
VALUE
GAS
FLOW
VALVE POSITION
CALCULATOR
REFERENCE
& TIMING
DESIRED
POSITION
VALUE
CURRENT
CONTROL &
CURRENT
POWER
POSITION PD
CONTROL
FLOW PI
CONTROL
DESIRED
CURRENT
VALUE
GAS
FLOW
REF.
MIXER
DESIRED
GAS FLOW
VALUE
ACTUAL
GAS FLOW
VALUE
INSP. VALVE POSITION
FLOW
REF.
GAS
SUPPLY
PRESS.
FLOW CONTROL
300-A09E
INSPIRATORY
CONTROL