Electric power conversion systems – Current conversion – By circuit interrupter type
Utility Patent
2000-02-10
2001-01-02
Nguyen, Matthew (Department: 2838)
Electric power conversion systems
Current conversion
By circuit interrupter type
Utility Patent
active
06169682
ABSTRACT:
CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for NDFG SPARK REMOVAL CIRCUIT FOR AN AC/DC MOCROWAVE OVEN earlier filed in the Korean Industrial Property Office on Sep. 21, 1999 and there duly assigned Ser. No. 40530/1999.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a non-directional frequency generator spark removal circuit, and more particularly to a non-directional frequency generator spark removal circuit for removing the spark generated from the non-directional frequency generator during the conversion of direct current into alternating current.
2. Description of the Related Art
Generally, electronic appliances such as a microwave oven, etc., are designed to be driven solely by alternating current (hereinafter called AC), and accordingly has a shortcoming in that the electronic appliances can not be used in places such as the outdoors, in the vehicles such as a ship, airplane, etc. where the AC is not available. In order to solve such a problem, a non-directional frequency generator (hereinafter called NDFG) has been developed to convert direct current (hereinafter called DC) into AC in the places where the AC power source is not available.
The NDFG usually uses relays or semiconductor elements for its converting operation into AC. The conventional semiconductor type NDFG circuit, however, has many problems of increasing manufacturing cost due to the expensive semiconductor elements, output loss of the semiconductor elements due to the switching operation, and excessive heat generation due to the output loss, etc.
In order to solve the above problems, the same applicant disclosed NDFG utilizing rotational AC converter to convert DC into AC in the Korean Patent Application Nos.
98-18589
(filed May 22, 1998) and
98-21117
(filed Jun. 8, 1998), which have not been opened to the public yet.
Hereinafter, the above NDFG will be briefly described as a related art with reference to the accompanying drawings.
FIG. 1
is a circuit diagram of the NDFG driven by a DC power source and a magnetron driving section thereof according to the related art.
Referring to
FIG. 1
, the NDFG 100 includes a motor
110
for generating rotational force by being driven by a DC power source, a commutator
130
rotated by the motor
110
, and a plurality of brushes such as first, second, third, and fourth brushes
121
-
124
as shown in
FIG. 1
, which are in contact with the outer circumference of the commutator
130
. The commutator
130
includes a conductive part which is divided into at least two parts
132
a
and
132
b
as shown in
FIG. 1
, but into an even number of parts. The commutator
130
has an insulating part
133
of a certain width formed between the conductive parts
132
a
and
132
b.
The conductive parts
132
a
and
132
b
are in simultaneous contact with at least two neighboring brushes of the brushes
121
-
124
. The DC is applied to input sides of the first to fourth brushes
121
-
124
, while the output sides of the first to fourth brushes
121
-
124
are connected with a high voltage transformer (hereinafter called HVT). The first and second relays RY
1
and RY
2
switch on/off the operation of the NDFG 100.
The operation of the NDFG 100 is as follows: When the first and second relays RY
1
and RY
2
are in the on-state, the commutator
130
is rotated by the DC power source. Accordingly, the brushes
121
-
124
in contact with the commutator
130
come in contact with the conductive part
132
a
, the insulating part
133
, the conductive part
132
b
, and the insulating part
133
which are formed on the outer circumference of the commutator
130
, sequentially.
More specifically, as the first brush
121
comes in contact with the conductive part
132
a
of the commutator
130
, the electric current from the positive (+) terminal of the DC power source is inputted into the first brush
121
, and flows through the conductive part
132
a
of the commutator
130
and the fourth brush
124
, and to the upper portion of the primary coil
202
of the HVT downwardly to the lower portion of the primary coil
202
of the HVT. Then, the electric current is inputted into the second brush
122
, and circulates through the conductive part
132
b
, the third brush
123
, and to the negative (−) terminal of the DC power source.
Next, as the commutator
130
is further rotated and as the first brush
121
accordingly comes in contact with the insulating part
133
, the electric current does not flow through the commutator
130
.
Then, as the commutator
130
is further rotated to 90°, the electric current from the positive (+) terminal of the DC power source is inputted into the first brush
121
, flows through the conductive part
132
b
of the commutator
130
and the second brush
122
, reverses its direction, and flows from the lower portion of the primary coil
202
of the HVT to the upper portion of the primary coil
202
of the HVT. Then, the electric current is inputted into the fourth brush
124
, flows through the conductive part
132
a
, and the third brush
123
, and then circulates to the negative (−) terminal of the DC power source.
By the constant rotation of the commutator
130
of the NDFG, the AC is generated at the primary coil
202
of the HVT in a manner as described above. Then the AC is transmitted to a secondary coil of the HVT through the primary coil
202
thereof. Then, the HVT converts the normal voltage into a high voltage, and the magnetron MGT is driven by the high voltage stepped-up by the HVT.
As described above, by the periodic contact of the brushes
121
-
124
with the conductive parts
132
a
and
132
b
during the rotation of the commutator
130
of the NDFG, DC is converted into AC. The problem is that there is excessive spark produced between the commutator
130
and the brushes
121
-
124
due to a low impedance of the HVT during the initial application of the DC to the NDFG. The spark becomes more excessive when the brushes enter into/escape from the contact with the conductive parts
132
a
and
132
b
of the commutator
130
.
SUMMARY OF THE INVENTION
The present invention has been developed to overcome the above-mentioned problems of the related art, and accordingly, it is an object of the present invention to provide a non-directional frequency generator spark removal circuit capable of removing the spark by performing pre-operation of intermittently applying a voltage prior to the actual operation of electronic appliances until a high voltage transformer thereof is increased to a certain impedance.
The above object is accomplished by a non-directional frequency generator spark removal circuit according to the present invention, including: a non-directional frequency generator having a direct current input end connected with a direct current power source, and an alternating current output end connected with an alternating current output section, for converting the direct current inputted from the direct current power source into alternating current, and for outputting the alternating current to the alternating current output section; first and second switching sections connected with the direct current input end and the alternating current output end, respectively, for controlling a conducting status between the direct current input end and the alternating current output end of the non-directional frequency generator; and a third switching section connected in parallel with the first switching section, for intermittently switching so as to control the conducting status of the non-directional frequency generator.
The third switching section is an integrated gate bipolar transistor, and the intermittent switching of the third switching section is kept being performed until the impedance of a high voltage transformer connected with the alternating current output end is increased to a certain impedance. Further, during the intermittent switching of the third switching se
Han Yong-Woon
Jang Seong-deog
Kang Kwang-Seok
Sung Han-Jun
Bushnell , Esq. Robert E.
Nguyen Matthew
Samsung Electronics Co,. Ltd.
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