Description Of Operating Sequence - Panasonic NN­GS595A Service Manual

10/24/2016
2 DESCRIPTION OF OPERATING
SEQUENCE
2.1 Variable power cooking control
High Voltage Inverter Power Supply (U) controls output power by the signal from Digital Programmer Circuit (DPC). Power relay
always stays ON, but PWM (pulse width modulation) signal controls microwave output power.
NOTE:
The ON/OFF time ratio does not correspond with the percentage of microwave power since approximately 2 seconds are
required for heating of magnetron filament.
SETTING
POWER
ON(SEC)
HIGH 100%
MEDIUM­HIGH 70%
MEDIUM 55%
MEDIUM­LOW 40%
LOW 20%
DEFROST 30%
2.2 Inverter power supply circuit NEW H.V.
The Inverter Power Supply circuit powered from the line voltage, 220V 50Hz AC input supplies 4,000V DC to the magnetron tube,
and functions in place of the H.V. transformer, the H.V. capacitor and H.V. diode.
1. The AC input voltage 220­240V 50Hz is rectified to DC voltage immediately.
2. DC voltage will be supplied to the switching devices called IGBT. These devices are switched ON­OFF by the 20 to 40
KHz PWM (pulse width modulation) signal from the microcomputer in the DPC.
3. This drives the High voltage transformer to increase voltage up to 2,000V AC.
4. Then the half­wave doubler voltage rectifier circuit, consisting of the H.V. diodes and capacitors, generates the
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.
6. This signal is fed back to the microcomputer in the DPC to determine operating conditions and output necessary to
control PWM signal to the Inverter Power Supply for control of the output power.
2.3 Steam defrost, Auto cook & Steam reheat
When the Auto Control feature is selected and the Start pad is 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.
Steam Defrost
SELECTED WEIGHT COOKING TIME
1.0 kg
Auto Cook (Rice)
SELECTED WEIGHT COOKING TIME
0.2 kg
file:///C:/Users/sh.dehghani/Desktop/NN­GS595AOTSVC_PHAMOS0511035C3/viewing/SGML_VIEW_DATA/OT/NN­GS595A/SVC/PHAMOS0511035C3/inde...
Variable Power Cooking
APPROX. MANUAL MICROWAVE DUTY
OUTPUT POWER(%)
OFF(SEC)
22 0
22 0
22 0
22 0
13 9
17 5
15 min.20 sec.
20 min.00 sec.
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