JP3469056B2 - Electrical equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric device provided with a plurality of noise filters for removing conduction noise from a plurality of switching power supply circuits.

[0002]

In an electric device, in particular, one having an inverter circuit for performing high frequency switching as a switching power supply circuit, the high frequency conduction noise generated by the switching operation flows out to the input power supply line, and the same input is generated. EMI (electromagnetic interference) such as malfunction, failure, noise mixing, etc. for other electrical equipment connected to the power line
cause. Therefore, a noise filter is inserted between the input power source and the input terminal of the inverter circuit as one means for suppressing the conduction noise to a regulation value according to a predetermined standard.

FIG. 3 is a connection diagram showing an example of a conventional configuration of a noise filter in an electric device, for example, an electromagnetic cooker, which has taken the above measures. First, the noise filter 32a, which is connected between the input terminals 42 and 43 and the output terminals 38a and 39a and is surrounded by a dashed line in the figure, includes a common mode coil 33a, a power source side line capacitor 34a, a load side line capacitor 35a, and Line bypass capacitor 36
a, 37a. In addition, the input terminal 42,
The noise filter 32b, which is connected between the output terminal 38b and the output terminals 38b and 39b and is surrounded by an alternate long and two short dashes line in the drawing, has the same configuration. Then, these two noise filters 32
A noise filter device 31 composed of a and 32b and surrounded by a broken line in the drawing is mounted on a substrate, and input terminals 42 and 43 shared by the two noise filters 32a and 32b are connected to an input power source 46 such as a commercial power source. , Noise filter 32
The output terminals 38a and 39a of a are connected to the inverter circuit 47,
The output terminals 38b and 39b of the noise filter 32b are connected to the inverter circuit 48, respectively.

In the above conventional structure, the input current of the inverter circuit 47 is supplied from the input power supply 46 to the noise filter 32.
Since it is supplied through the noise source 32a, the conduction noise flowing from the inverter circuit 47 to the input power supply 46 is suppressed by the noise filter 32a, and the input current of the inverter circuit 48 is supplied from the input power supply 46 through the noise filter 32b. Input power supply 4 from the inverter circuit 48
The conduction noise flowing out to 6 is suppressed by this noise filter 32b.

Further, in the above-described structure in which the noise filters 32a and 32b are provided independently of each other for the inverter circuits 47 and 48, the noise filters 32a and 32b are provided.
The current ratings of the common mode coils 33a and 33b are such that the inverter circuits 47 and 48 connected to the common mode coils 33a and 33b can be operated in rated operation, respectively. It is set according to the value.

However, normally the inverter circuit 4
Common-mode coil 33 when rated operation of 7, 48
There is a problem that the temperature rise of a and 33b is large, and therefore the magnetic characteristics of the common mode coils 33a and 33b are deteriorated, the filter characteristics are deteriorated, and the reliability as an electric device is deteriorated. On the other hand, in order to suppress the temperature rise, it is conceivable that the common mode coils 33a and 33b have a sufficient current rating, but in this case, the common mode coils 33a and 33b become large and the degree of freedom in mounting design is impaired. In addition to being costly, it causes high costs.

Further, in the case of adjusting the noise filter device 31 having the above-mentioned conventional structure, the noise filter 32a alone in which the respective constants are adjusted so as to optimally suppress the conduction noise from the inverter circuit 47, and the inverter circuit 48.
The noise filter 32b alone whose constants are adjusted so as to optimally suppress the conduction noise from the sensor and the input busbars 44 and 4 of both the noise filters 32b are mounted on the same substrate as described above after each adjustment.
If 5 is used in common, there arises a problem that the filter characteristics adjusted by each noise filter alone cannot be reproduced. This is affected by mutual components of the noise filters 32a and 32b (especially capacitors 34a and 34b between power supply lines) because the input power supply sides of the noise filters 32a and 32b are connected by the input buses 44 and 45. It depends. As a result, a plurality of noise filters 32a, 32
When using b, the total noise filters 32a, 32
It is necessary to readjust each constant in the actual use state in which all the inverters 47 and 48 are connected to each other, and in that case, the constant change of each component is the characteristic of all the noise filters 32a and 32b as described above. Therefore, there is a problem that it is difficult to adjust the constant.

If the current capacities of the inverter circuits 47 and 48 are different, the constituent parts of the noise filters 32a and 32b connected to the input terminals are also different, so that the output terminals 38a, 39a and 3 of the noise filters 32a and 32b are different.
If the connection relationship between the inverter circuits 8b and 39b and the inverter circuits 47 and 48 is incorrect, a current exceeding the design value may flow through the noise filter 32a or 32b and the components may be overheated.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a plurality of switching power supply circuits and a plurality of noises respectively inserted between the input terminals and the input power supplies of these switching power supply circuits. in the electric apparatus having a filter, a large effect of suppressing the conduction noise with a current rating and temperature rise can be set lower than each conventional noise filter, further to easily adjust the constants, and when the equipment assembly It is to provide an electric device that is hard to be miswired.

[0010]

In order to achieve the above object, the present invention has a plurality of switching power supply circuits and a common mode coil inserted between the input terminals and the input power supplies of these switching power supply circuits. in the electric apparatus having a plurality of noise filters formed by, as well as connecting the common-mode coil of said plurality of noise filters connected to the same input power in parallel, a plurality of Noizufu
Common line capacitor provided on the input power side of the filter
The present invention has the constitution (the invention of claim 1).

According to this invention, the input current from the input power supply to the switching power supply circuit is shunted to each common mode coil connected in parallel, and the current flowing through each common mode coil is reduced. The temperature rise of the mode coil is suppressed, and the current rating of the common mode coil can be lowered. Further, when the current of the common mode coil is decreased and the temperature is decreased, the magnetic characteristics of the core are not deteriorated, so that the effect of suppressing noise is increased. Furthermore, since each output terminal of the plurality of noise filters connected in parallel can be wired to any input terminal of the plurality of switching power supply circuits connected to them, miswiring is less likely to occur.

In this case, the common mode coils connected in parallel can have the same current rating (the invention of claim 2). According to this invention, current flows evenly through the common mode coil. In addition, in a plurality of noise filters, it is preferable to connect one common line capacitor on the input power supply side of the common mode coil (the invention of claim 3). According to this invention, the same noise suppression effect as when connecting the line capacitors to the respective noise filters can be obtained.

In this case, the plurality of noise filters can be mounted on a glass epoxy double-sided board (the invention of claim 4). According to this invention, the heat generated from the components of the noise filter, particularly the common mode coil, can be effectively radiated through the substrate, and the temperature rise of the common mode coil can be suppressed.

Further, the common mode coil may be arranged on a straight line which is perpendicular to the cooling air (the invention of claim 5). According to this invention, the common mode coil is uniformly cooled by the cooling air. Then, the load side terminal of the noise filter may be used as a tab terminal, and all the tab terminals at the same potential may be arranged so that their longitudinal directions are aligned (invention of claim 6). According to this invention, tab terminals having different potentials can be easily identified.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to an electromagnetic cooker will be described below with reference to FIGS. 1 and 2. In FIG. 1, a noise filter device 1 surrounded by a broken line is a noise filter 2a connected between input terminals 11 and 12 and output terminals 7a and 8a and surrounded by a dashed line in the drawing.
And a noise filter 2b connected between the input terminals 11 and 12 and the output terminals 7b and 8b and surrounded by a two-dot chain line in the figure.

The noise filter 2a has an input terminal 1
A power source side line capacitor 15, which is connected between the input buses 13 and 14 respectively connected to 1 and 12, and which is shared with the noise filter 2b, and a common mode coil which is inserted between the input buses 13 and 14 and the output buses 9a and 10a. 3a, output terminal 7
load side line capacitor 4a connected between output busbars 9a and 10a respectively connected to a and 8a, and output busbar 9a,
It is composed of line bypass capacitors 5a and 6a which are respectively connected between 10a and ground. Here, the common mode coil 3a is a four-terminal choke coil in which two windings are wound by the same number of turns on a toroidal core,
These two coils form a coupling relationship between the input bus bar 13 and the output bus bar 9a and between the input bus bar 14 and the output bus bar 10a to mutually cancel the magnetic flux against the current from the input bus bar side to the output bus bar side. To be connected.

Since the noise filter 2b has the same structure as the noise filter 2a, the description of the same parts will be omitted by adding b to the reference numerals instead of the subscript a. However, the power line side line capacitor 15 connected between the input buses 13 and 14 is the noise filter 2
a and the noise filter 2b are used in common and function as a filter capacitor for both.

Furthermore, the output bus 9 of the noise filter 2a
a and the output busbar 9b of the noise filter 2b, and the output busbar 10a of the noise filter 2a and the output busbar 10b of the noise filter 2b are connected to each other, whereby the common mode coil 3a and the common mode coil 3b are configured in parallel.

Further, the noise filter 2a and the noise filter 2b are all made of the same rated product, and the constant thereof is, for example, 0.68μ for the power supply side line capacitor 15.
F, common mode coils 3a, 3b are 0.9 mH, 15
A, the load side line capacitors 4a and 4b are 2.5 μF, and the line bypass capacitors 5a, 6a, 5b and 6b are 33.
It is 00 pF.

Now, the input terminals 11 and 12 of the noise filter device 1 provided in the electromagnetic cooker as the electric equipment.
A commercial power supply of, for example, a single-phase 200V is connected as an input power supply 16 to one of the output terminals 7 of the noise filter device 1.
In a and 8a, an inverter circuit 17 (rated input current 15A) with a rated output of 3kW is used as a load of the noise filter 2a.
However, the noise filter 2b is connected to the other output terminals 7b and 8b.
Inverter circuit with rated output of 2kW and 1.2
A kW heater (rated input current 16A, hereinafter simply referred to as an inverter circuit 18) is connected. Then, power demand control is performed so that the total input current value of both inverter circuits 17 and 18 is within 24A. An inverter circuit 17 as these switching power supply circuits,
Reference numeral 18 is for applying a high frequency current to the induction heating coil to heat the pot placed on the induction heating coil by heat generation based on eddy current loss. In both cases, a rectifier circuit (not shown) and a plurality of switching elements are bridge-connected. The inverter main circuit is composed of the following inverter main circuits, and these inverter main circuits are switching-controlled by a microcomputer as a control means.

FIG. 2 is a board plan view showing a mounted state of the noise filter device 1 on a board. The noise filter device 1 is mounted on a glass epoxy double-sided board 19, and terminals 2 as input terminals 11 and 12 are provided on the board.
0 and 21 are provided side by side in the lateral direction, and tab terminals 2 as output terminals 7a and 7b, which are at the same potential, are provided on the lower portion of the substrate.
3, 25 and the other tab terminals 24, 26 as the output terminals 8a and 8b at the same electric potential are arranged so that the longitudinal directions of the tab terminals at the same electric potential are aligned.

Slightly above the central portion of the substrate surface, the common mode coils 3a and 3b are provided with respect to the cooling air flowing from the top to the bottom of the drawing with the toroidal surfaces of the toroidal cores parallel to the substrate. Are arranged on a straight line that is vertical. Also, although not shown, the power supply side line capacitor 1
5, load-side line capacitors 4a and 4b, and line bypass capacitors 5a, 6a, 5b, and 6b are arranged on the substrate 19.

Further, on the surface of the substrate 19, a pattern 27 as a bus bar 13 which extends downward from the terminal 20 and is branched into two and connected to the input ends of the common mode coils 3a and 3b, respectively, and these input ends. On the other hand, the U-shaped pattern 29 as the busbars 9a and 9b, which extend downward from the output end serving as the other end of the coil and are connected in the lateral direction at the positions of the tab terminals 23 and 25, is substantially O-shaped as a whole. It is formed in a shape. Similarly, on the back surface of the substrate 19, a pattern 28 as a busbar 14 extending downward from the terminal 21 and then branched in two directions and connected to the input ends of the common mode coils 3a and 3b, respectively, and to these input ends. The tab terminals 24, 2 extend downward from the output end, which is the other end of the coil, respectively.
Busbars 10a, 10b that connect the two in the horizontal direction at the position of 6
And a U-shaped pattern 30 as a whole are formed in a substantially O shape. The ground pattern and the ground terminal are not shown in FIG.

Next, the operation of this embodiment will be described.
Since the common mode coils 3a and 3b are connected in parallel and configured with the same current rating, the input power source 1
The input current flowing from 6 to the inverter circuit 17 and the input current flowing from the input power source 16 to the inverter circuit 18 are evenly shunted to both common mode coils 3a and 3b. At this time, the conduction noise generated in each of the inverter circuits 17 and 18 is the noise filter 2a, 2 through which the input current passes.
In b, it is suppressed by the same amount to prevent the high frequency conduction noise from flowing out to the commercial power source which is the input power source 16.

Table 1 shows the results of the temperature rise test of the common mode coil in the present embodiment shown in FIG. 1 and the conventional example shown in FIG. Noise filter device 3 in a conventional example
The constants of 1 are the same as the constants of this embodiment described above (both the power supply side line capacitors 34a and 34b are 0.68 μF).
And the board mounting is the same as that of the present embodiment.
In the test, when the rated input current 15A is applied only to the inverter circuit A (17, 47), the inverter circuit B (1
8, 48) only when the rated input current of 16 A is passed, and when the demand control of electric power is performed, the inverter circuit A
When the rated input current of 15 A is applied to (17, 47) and the input current of 9 A is applied to the inverter circuit B (18, 48), continuous operation is performed in an environment of an indoor temperature of 30 ° C. and the temperature of the common mode coil of the noise filter. The rise was measured.

[0026]

[Table 1]

First, in the noise filter device 31 of the conventional construction in which independent noise filters are provided for the respective inverter circuits, when the rated input current is passed through only one of the inverter circuits, all the currents are connected to the inverter circuit. The temperature rise is large because it flows through the common mode coil, and rises to 108 ° C. when the passing current is 15 A and to 123 ° C. when the passing current is 16 A. At this time, no current flows in the other common mode coil, but since the ambient temperature of the noise filter device 31 is rising,
The temperature becomes higher than the room temperature. Further, in the case of demand control, since 15 A flows in the common mode coil 33a and 9 A flows in the common mode coil 33b, the temperature rise of the common mode coil 33a is larger than that of the common mode coil 33b.

On the other hand, in the noise filter device 1 of this embodiment in which the common mode coils are connected in parallel, the input current to the inverter circuits 17 and 18 is two common mode coils 3.
Since the currents evenly flow in a and 3b, when the rated input current is passed through only one of the inverter circuits, the current flowing through each common mode coil is ½ of the rated input current. Therefore, in this embodiment, the temperature rise is small compared to the conventional common mode coil in which the rated input current flows as it is, and the rated input current 1 is applied only to the inverter circuit A (17).
1 to when the rated input current of 16A is applied only to the inverter circuit B (18) when 108A to 50 ° C when 5A is applied.
Significant improvement from 23 ° C to 53 ° C. Also, control value 2
Even in the case of the 4A demand control, the current that is biased in the common mode coil 33a in the conventional example is
Since 12A flows evenly to both common mode coils,
The temperature rise value of the common mode coil on the inverter circuit A side drops from 108 ° C to 78 ° C.

Next, the measurement result of the noise terminal voltage will be described with reference to Table 2. The constants and the board mounting of the noise filter device 31 in the conventional example of Table 2 are also set in the same manner as the noise filter device 1 of the present embodiment. Only the inverter circuit A (17, 47) is measured for its rated input current 15A.
It was carried out for the case of flowing. In addition, the allowable values in the lower part of Table 2 show the regulated values under the Electrical Appliance and Material Control Law.

[0030]

[Table 2]

As a result, in this embodiment, as compared with the conventional example, 5
It can be seen that the noise terminal voltage is reduced by 10 dB at frequencies below MHz and 14 dB at frequencies above 5 MHz, and the effect of suppressing conduction noise is increased.
This is because the common mode coils are connected in parallel and the current flowing through each common mode coil is reduced, so that the temperature of the common mode coil is reduced and the deterioration of the magnetic characteristics of the core is improved.

Further, the relationship between the number of capacitors in the noise filter device 1 and the noise terminal voltage was measured. As a result, if the number of line bypass capacitors is twice the number of common mode coils (two), the noise terminal voltage is about 2 dB lower at frequencies below 5 MHz and at frequencies above 5 MHz compared to the same number. Did not make a difference. When the number of load-side line capacitors is the same as the number of common mode coils (two), the noise terminal voltage is 5MHz compared to half the number.
It decreased about 3 dB at the following frequencies and about 4 dB at frequencies above 5 MHz. Further, although the number of power source side line capacitors is increased to two or more, there is no change in the noise terminal voltage, and as shown in this embodiment, one power source side line capacitor is provided by the noise filter 2a and the noise filter 2b. By sharing 15, the cost can be reduced without deteriorating the noise terminal voltage.

As described above, according to this embodiment, a plurality of inverter circuits 17 for supplying a high frequency current to the induction heating coil,
18 and an electromagnetic cooking device including a plurality of noise filters 2a and 2b having common mode coils 3a and 3b inserted between the input terminals of these inverter circuits 17 and 18 and a commercial power source as the input power source 16 Since the common mode coils 3a and 3b of the plurality of noise filters 2a and 2b are connected in parallel and have the same current rating, the input current to the inverter circuits 17 and 18 is applied to the common mode coils 3a and 3b. The current is shunted evenly, and the passing current is reduced to 1/2 of the demand-controlled current value even at the maximum. As a result, the temperatures of the common mode coils 3a and 3b are lowered, reliability and safety are improved, and a common mode coil having a smaller current rating and smaller size and lower cost than the conventional one can be adopted. Further, the current in the common mode coil is reduced and the core temperature is also lowered, so that the effect of suppressing conduction noise is increased.

In the present embodiment, the noise filters 2a and 2b are mounted on the glass epoxy double-sided substrate 19 having excellent heat conduction, and the common mode coils 3a and 3b are arranged on a straight line which is perpendicular to the cooling air. A cooling effect is obtained. Moreover, since the pattern is a double-sided pattern, the pattern design of the substrate is easy and the substrate size can be made small. At this time, since the longitudinal directions of the tab terminals 23 and 25 and the tab terminals 24 and 26, which are at the same potential, form a straight line,
The tab terminals having different potentials can be easily identified, and miswiring is reduced.

Further, since the common mode coils 3a and 3b are connected in parallel and the power supply side line capacitor 15 is shared by the noise filters 2a and 2b, each noise filter is less susceptible to the constant of the other noise filter. ,
As well as facilitating constant adjustment of the noise filter device 1,
The cost can be reduced. Since the common mode coils 3a and 3b are connected in parallel, the output terminal 7a
And the output terminal 7b, and the output terminal 8a and the output terminal 8b become the same potential, respectively, and these output terminals 7a, 8a and 7b, 8
b can be connected to either of the inverter circuits 17 and 18.

The present invention is not limited to the embodiments described above and shown in the drawings. For example, the present invention is applied not only to an electromagnetic cooker using a plurality of inverter circuits but also to electric appliances in general using a switching power supply circuit. It can be implemented by appropriately modifying it within a range not departing from the gist of the invention.

[0037]

According to the first aspect of the present invention, since the common mode coils of the plurality of noise filters are connected in parallel, the passing current of the common mode coil can be reduced. Therefore, the temperature of the common mode coil is lowered and the reliability and reliability are improved. Safety is improved. Further, since the common mode coil can be downsized, the cost can be reduced and the flexibility in mounting design can be increased. Furthermore, the noise suppression effect increases as the passing current decreases.

According to the second aspect of the invention, since the common mode coils have the same current rating, the input current of the switching power supply circuit is shunted evenly to each common mode coil. Therefore,
The temperature rise of each common mode coil can be minimized. According to the third aspect of the present invention, one power source side line capacitor can be commonly used by a plurality of noise filters without impairing the noise suppressing effect, so that the cost can be reduced and the mounting design can be improved. More freedom,
Adjustment of the constant becomes easy.

According to the fourth aspect of the invention, since the plurality of noise filters are mounted on the glass epoxy double-sided board, the heat generated by the components can be efficiently dissipated. Further, by using the double-sided pattern, the pattern design of the substrate can be facilitated and the substrate size can be reduced.

In the invention of claim 5, since the common mode coil is arranged on a straight line which is perpendicular to the cooling air,
The temperature rise can be effectively suppressed. In the invention of claim 6, since the tab terminals at the same potential are aligned in the longitudinal direction, the tab terminals having different potentials can be easily discriminated from each other, erroneous wiring is less likely to occur, and manufacturability is good.

[Brief description of drawings]

FIG. 1 is a connection diagram of a noise filter device provided in an electric device according to an embodiment of the present invention.

FIG. 2 is a plan view of the substrate of the noise filter device.

FIG. 3 is a diagram corresponding to FIG. 1 showing a conventional noise filter device.

[Explanation of symbols]

1, 31 are noise filter devices, 2a, 2b, 32a,
32b is a noise filter, 3a, 3b, 33a, 33b
Is a common mode coil, 15, 34a, 34b are power source side line capacitors, 4a, 4b, 35a, 35b are load side line capacitors, 5a, 5b, 6a, 6b, 36a, 3
6b, 37a, 37b are line bypass capacitors, 1
Reference numerals 7, 18, 47, and 48 denote inverter circuits, and 23 to 26 denote tab terminals.

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Claims (6)

(57) [Claims] 1. An electric device comprising a plurality of switching power supply circuits and a plurality of noise filters each having a common mode coil inserted between an input terminal and an input power supply of the switching power supply circuit, a common mode coil of said plurality of noise filters connected to the same input power as well as connected in parallel, the plurality of Neu
The line-to-line capacitor provided on the input power side of the filter
Electric equipment characterized by being shared . 2. The electric device according to claim 1, wherein the common mode coils connected in parallel have the same current rating. 3. The electric device according to claim 1, wherein in the plurality of noise filters, one common line capacitor is connected to the input power source side of the common mode coil. 4. The electric device according to claim 1, wherein a plurality of noise filters are mounted on a glass epoxy double-sided substrate. 5. The common mode coil is arranged on a straight line perpendicular to the cooling air.
The listed electrical equipment. 6. The electric device according to claim 4, wherein the load-side terminals of the noise filter are tab terminals, and all the tab terminals at the same potential are arranged so that their longitudinal directions are aligned.