ETAS
Hardware Description
ES430.1 - User’s Guide
23
• Internal resistance of the lambda sensor R
i
• Pump current of the lambda sensor I
p
The Lambda Module ES430.1 is set to a curve determined on test benches for
operation with the lambda sensor LSU4.9.
For the complete technical data of the ES430.1, refer to the chapter “Technical
Data” on page 79.
4.2
Block Diagram
The ES430.1 is a module with electronics which provide all signals necessary
for operating a broadband lambda sensor. A microprocessor system with two
Ethernet interfaces processes the acquired values. In addition, a value can be
issued at a galvanically isolated analog output.
Fig. 4
-
2
Block Diagram
The electronics control the heating of the sensor to guarantee the correct oper
-
ating temperature. The internal resistance of the sensor element is used as the
measure for its temperature. By controlling the pump current, a constant volt
-
age is set at the Nernst concentration cell. The lambda value can be calculated
from the pump current measured.
4.3
Measurement Channel
The measurement channel consists of the function groups input stage, signal
processing with filter, heater control, cable identification and a galvanically iso
-
lated analog output.
4.3.1
Signal Processing and Filters
In pump current measuring, the amplified signal of the pump current controller
is filtered with a Bessel 2nd order low-pass with 100 Hz cutoff frequency. An A/
D converter digitizes this pump current signal with a sampling rate of 2 kHz.
Sampling takes place synchronously with other devices of the ES400 family. A
digital Bessel 4th order low-pass which can be disabled and adjusted is used to
further smooth the pump current signal.
The microprocessor software calculates the values for lambda, oxygen content
and the air/fuel ratio from the pump current.
FPGA
Ethernet
Phy
Ethernet
Traf f ic
Det ect ion
100
MBit/s
Et hernet
Connector
(Host
direction)
M
eas
u
rem
en
t
C
ontr
o
ll
er
C
o
mm
uni
ca
ti
on
C
ontr
o
ll
er
Ti
m
e
Sy
nc
hr
oni
za
ti
on
Un
it
Ethernet
Phy
100
MBit /s
Et hernet
Connect or
On
Automat ic
P
rotoc
o
l
E
ng
ine
Frame
Generator
Volt age
Regulat or
5...50V
A
na
log
O
ut
p
ut
C
ontr
o
ll
er
Lambda
Sensor
ASIC
Isolated
Power Supply
Short circuit
protection
Output Diag.
Low side
switch
H
eater
C
ontr
ol
er
Power supply
TEDS
G
a
lv
ani
c Is
ol
ati
o
n
A
D
Activate
Heater
Ubatt
Heater
Heater
UN / VM / IP
A
D
A
D