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3.1. Variable power cooking
control
High Voltage Inverter Power supply (U) controls output power
by the signal from Digital Programmer Circuit (DPC). Power
relay stays ON for P3 to P10 and For P1 to P2, both inverter
drive signal and power relay to control output power.
by the signal from Digital Programmer Circuit (DPC). Power
relay stays ON for P3 to P10 and For P1 to P2, both inverter
drive signal and power relay to control output power.
NOTE:
The ON/OFF time ratio does not correspond with the
percentage of microwave power since approximately 2
seconds
percentage of microwave power since approximately 2
seconds
are
required
for
heating
of
magnetron
filament.
Variable Power Cooking
POWER SETTING
OUTPUT
POWER(%)
APPROX.
ON-OFF TIME OF
POWER RELAY (RY1)
ON(SEC)
OFF(SEC)
HIGH
P10
100%
22
0
P9
90%
22
0
P8
80%
22
0
MEDIUM-HIGH
P7
70%
22
0
MEDIUM
P6
60%
22
0
P5
50%
22
0
P4
40%
22
0
MEDIUM-LOW
P3
30%
22
0
P2
20%
15
7
LOW
P1
10%
8
14
DEFROST
P3
30%
22
0
3.2. Inverter power supply circuit
NEW H.V.
This Inverter Power Supply Circuit supplies 4,000V DC to the
magnetron tube from the line voltage, 220-240V 50Hz/60Hz AC
input. functions as the H.V. transformer, the H.V.capacitor and
H.V.diode.
magnetron tube from the line voltage, 220-240V 50Hz/60Hz AC
input. functions as the H.V. transformer, the H.V.capacitor and
H.V.diode.
1. The AC input voltage 220-240V 50Hz/60Hz is rectified to
DC voltage immediately.
2. DC voltage will be supplied to the switching devices called
IGBT. These devices will be switched ON-OFF by the 20 to
40 KHz PWM(pulse width modulation) signal from the
microcomputer in the DPC.
40 KHz PWM(pulse width modulation) signal from the
microcomputer in the DPC.
3. This drives the High voltage transformer to increase up to
2,000V AC and approximately 3V AC by means of
transformer.
transformer.
4. Then
the
half-wave
doubler
voltage
rectifier
circuit,
consisting of the H.V. diodes and Capacitors, generates the
necessary 4,000V DC needed for the magnetron.
necessary 4,000V DC needed for the magnetron.
5. Output power of the magnetron tube is always monitored by
the signal output from the current transformer built into the
inverter circuit.
inverter circuit.
6. Then this signal will be fed back to the microcomputer in the
DPC
to
determine
operating
conditions
and
output
necessary to control PWM signal to the Inverter Power
Supply to control output power.
Supply to control output power.
3.3. Inverter turbo defrost
When this Auto Control feature is selected and the Start Pad is
tapped:
tapped:
1. The digital programer circuit determines the power level and
cooking time to complete cooking and indicates the
operating state in the display window. Table shows the
corresponding cooking times for respective serving by
categories.
operating state in the display window. Table shows the
corresponding cooking times for respective serving by
categories.
2. When cooking time the display window has elapsed, the
oven turns off automatically by a control signal from the
digital programmer circuit.
digital programmer circuit.
3 DESCRIPTION OF OPERATING SEQUENCE
7
NN-S453WF
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