4
230V
2
2
T
T
H
H
E
E
S
S
T
T
R
R
U
U
C
C
T
T
U
U
R
R
E
E
A
A
N
N
D
D
W
W
O
O
R
R
K
K
I
I
N
N
G
G
P
P
R
R
I
I
N
N
C
C
I
I
P
P
L
L
E
E
O
O
F
F
M
M
I
I
C
C
R
R
O
O
W
W
W
W
A
A
V
V
E
E
O
O
V
V
E
E
N
N
.
.
Microwave oven can be classified to many kinds
according to various construction, volume and control
function. But anyhow, the main electric parts are all
composed of high voltage rectification, cooling system.
Microwave generator, electric control system and heating
chamber (FIG.2-1). Its working process are as follows:
230V power frequency voltage transferred to the rectifier
through electric control system, and then be changed to
4000V direct volt-age by the rectifier, and be then
transferred to the microwave generator, the generator
stars working to transfer the microwave energy to the
heating chamber for heating food through wave guide
tube. At the same time, the electric control system set off
the cooling system to cool the working rectifier and the
microwave generator to keep the oven working steadily
from a too high temperature. If something wrong with the
cooling system cause the temperature too high, the control system would cut off the power automatically to
prevent microwave generator being damaged form the high temperature. Now, we’d like to introduce the working
principle of each part of the widely used model, mechanical control and touch control microwave oven.
2
2
.
.
1
1
H
H
I
I
G
G
H
H
V
V
O
O
L
L
T
T
A
A
G
G
E
E
R
R
E
E
C
C
T
T
I
I
F
F
Y
Y
I
I
N
N
G
G
C
C
I
I
R
R
C
C
U
U
I
I
T
T
.
.
At present, home use microwave oven adopt this high voltage rectifying circuit as shown at diagram 2-2.The
circuit is a single phase, semi-wave, double voltage rectifying circuit. The circuit has only a high voltage capacitor,
a high voltage diode, a magnetic leakage transformer besides the magnetron, is very simple.
The working principle of the circuit: 230V power boosted through the transformer, output about 2000V alternating
high voltage current when the high voltage winding is at the positive half-circle, the high voltage winding is at the
negative half-circle, the diode is cut off and the magnetron is conducted. The electricity charged at the positive
half-circle of the capacitor is series connected with the positive phase of the winding voltage, and got a doubled,
about 4000V direct high voltage, then transferred to between the cathode and the anode of the magnetron.
2
2
.
.
2
2
M
M
I
I
C
C
R
R
O
O
W
W
A
A
V
V
E
E
G
G
E
E
N
N
E
E
R
R
A
A
T
T
E
E
R
R
.
.
Microwave generator is the heart of microwave oven. The quality of a microwave oven mostly depends on the
quality of the microwave generator. A microwave generator is mainly composed of magnetron and its power
supply circuit, FIG.2-3 is the typical circuit diagram of the present used microwave oven’s generator. The power
supply circuit is composed of rectifying circuit and filament circuit.
Usually, we adopt continuous wave magnetron. It can turn the direct energy which is applied to the magnetron
after being high voltage rectified to microwave energy, the power supply circuit supply a direct high voltage
Fig.2-2
Fig.2-3
230V
230V
