JPH10200358A - Conduction noise eliminating filter constant selector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently select a filter constant for eliminating conduction noise by constituting a filter circuit while selectively combining respective circuit constants. SOLUTION: An AC power source is connected through a pseudo power supply circuit network 2 and a filter selector circuit 1 to a sampler 4 and at such a time, the noise generated from the sampler 4 and conducted to the side of the power source is taken out by the pseudo power supply circuit network 2 and measured by a spectrum analyzer 3. Namely, the noise level at that time is measured by the spectrum analyzer 3 and the constant is selected while performing the selection of a filter circuit and the selection of a circuit constant through the filter selector circuit 1. Thus, by inserting the filter selector circuit 1 between the sampler 4 and the pseudo power supply circuit network 2, the selection of the filter circuit or the filter constant can easily be performed without executing the disassembly or soldering work of the sampling equipment 4 so that work can remarkably be improved and the selecting work can efficiently be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for regulating noise generated and transmitted from an electric product, and more particularly to an apparatus capable of efficiently selecting a filter constant for removing a transmission noise. is there.

[0002]

2. Description of the Related Art Various electric and electronic equipment products are manufactured by EMI.
(Electro MagneticInterfer
It is necessary to suppress electromagnetic noise generated from a power supply line or the like due to regulations, such as noise and electromagnetic interference. Such regulations mainly deal with noise in the AM radio band, and particularly in the case of home electric appliances, which are strictly regulated. Therefore, measures must be taken to satisfy the regulations.

As one of the methods, a filter circuit using a capacitor and a coil is mounted on a power supply portion of a device. This filter circuit is used to reduce noise generated by the device and characteristic impedance of the device. The constant is not constant due to the problem.

Therefore, in order to select a constant of a filter circuit, conventionally, a device is disassembled and a capacitor component and the like of a power supply portion are soldered or screwed or the like. I was experimenting.

[0005]

In such a conventional method, various operations, such as disassembly of the device, increase the time required for EMI measures, or the device is repeatedly disassembled and damaged by repeated soldering. There was a problem.

Further, even if a filter constant that matches the EMI regulation value is determined, a case may occur in which the determined filter constant cannot be used safely due to a leakage current test. In this case, there is a problem that the operation of selecting the filter constant must be performed again.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a conduction noise elimination filter constant selection apparatus capable of efficiently selecting a filter constant for eliminating conduction noise. .

[0008]

SUMMARY OF THE INVENTION To this end, the present invention is an apparatus for selecting a constant of a filter circuit for removing noise transmitted from a test apparatus through a line, wherein the circuit element includes a plurality of types of circuit elements constituting the filter circuit. A unit, by-passing the circuit element unit, or selecting means for selecting an element having a predetermined constant from the circuit element unit, and display means for displaying the selected circuit and circuit element, and A filter circuit is configured by selecting and combining circuit constants.

[0009]

Embodiments of the present invention will be described below. FIG. 1 is a diagram showing a schematic configuration of a conduction noise elimination filter constant selection device of the present invention. In FIG.
The AC power supply is connected to the EUT 4 through the pseudo power supply network 2 and the filter selection circuit 1. At this time, noise generated from the EUT 4 and transmitted to the power supply side is extracted by the pseudo power supply network 2, and the spectrum is extracted. The measurement is performed by the analyzer 3.

As will be described in detail later, the filter selection circuit 1 is a device for efficiently selecting a filter circuit and efficiently selecting a capacitor capacity and a coil inductance constituting the selected filter circuit. The constant is selected while observing the waveform, and the device of the present invention further includes a leakage ammeter.

The pseudo power supply network 2 is a constant impedance power supply for supplying power to the EUT 4 and includes therein the EUT 4.
It has an LC filter circuit that extracts noise transmitted from the power supply to the power supply side, and a commercially available product can be used.

The spectrum analyzer 3 displays the spectrum of the noise signal extracted by the pseudo power supply network 2, and a commercially available product can also be used.

Taking the case where the test device 4 is a home-installed electric device as an example, as shown in FIG.
In the 30 MHz band, the noise level is regulated to be 66 dB or less, and particularly to be 56 dB or less in the range of 500 KHz to 5 MHz. Therefore, the noise level at that time is measured by the spectrum analyzer 3 while selecting the filter circuit and the circuit constant by the filter selection circuit of FIG. 1, and the constant is selected so as to be lower than the level shown in FIG. Furthermore, in the case of home-installed electrical equipment, since the leakage current is regulated to 0.25 mA or less, the leakage current is measured, and if it is less than the specified value, the selected filter constant is used. In this case, the constant selection must be performed again.

FIG. 3 is an external view of a device incorporating the filter selection circuit 1, and FIG. 4 is a diagram showing an example of the filter selection circuit. FIG. 3A is a front view of the device, in which units 11 to 19 of each circuit element and a leakage ammeter 20 are provided, and each unit has a constant that can be changed according to the device under test. It is a box-type detachable replacement type, and can be mounted with various constant elements by replacement. When a component not mounted on the unit is used, the component is detached and replaced with an individual component unit as shown in FIG. 1C, and the individual component can be connected to the external terminal. FIG. 2B is a side view of the apparatus, in which a breaker 24 and an outlet 25 are provided.

The filter circuit constituted by the units of the respective circuit elements is displayed brightly by the backlight illumination by the circuit display lamp 21, and the constant of each unit can be selected by a selection switch 22 provided below the filter circuit. It has become. The part selected by the selection switch 22 is displayed as indicated by a black circle in the figure. In addition, the display of "None" of each circuit element unit indicates that the element is not used, and the drawing shows that the differential mode choke coil is not used.

The Y capacitor units 11, 14 and 18 are composed of a pair of capacitors connected in series between the lines to absorb high-frequency noise. A coil is connected so that components that cannot be absorbed by the capacitor can be canceled. The X capacitor units 12 and 15 are large-capacity capacitors connected to a constant resistor in parallel or used independently to smooth a signal. The common mode choke coil unit 13 is connected to both lines so as to cancel magnetic fields generated from each other, and cancels noise that is commonly transmitted through both lines as generated from the EUT. Differential mode choke coil units 16 and 17
It is connected to the line side or the neutral side, and suppresses noise transmitted through each line.

By using such a circuit element unit and sequentially selecting each circuit element with the selection switch 22 while observing the noise level with the spectrum analyzer 3 (see FIG. 1), the test apparatus can be disassembled. Also, the selection of the circuit without soldering the circuit elements, etc.
Circuit elements can be selected.

Next, an example of a filter selection circuit will be described with reference to FIG. The switches 30 to 44 are switches for deciding whether to bypass or connect each circuit element unit. When each switch is turned to the upper position, the circuit element unit is bypassed and not inserted, and corresponds to "None" in FIG. I do. When the switch is turned down, each switch is connected to one of the rotary switches 50 to 65, and the circuit element is connected.

For example, when selecting the X capacitor, the switches 33 and 34 or the switches 39 and 40 are turned down. In the case of the switches 33 and 34, when the switch is turned down, the switch 33 is connected to the connector A through the terminal a of the rotary switch 50, and the switch 34 is connected to the connector B through the terminal b of the rotary switch 51. . Seven capacitors are selectably connected between the connector A and the connector B, and a predetermined capacity is selected by selecting the interlocking rotary switches 50 and 51.

When selecting a Y capacitor, the switches 31 and 32, the switches 37 and 38, or the switches 43 and 44 are turned to the lower side in the figure. Switches 31, 3
In the example of FIG. 2, when the switch is tilted downward, the switch 3
1 is connected to the connector C through the terminal c of the rotary switch 52, and the switch 32 is connected to the rotary switch 53.
Is connected to the connector D through the d terminal. Connector C
Seven Y capacitors are connected between the power supply and the connector D. By rotating the rotary switches 52 and 53 in conjunction with each other, one of the capacitors is selected and connected between the lines. At this time, when the switch 30 is tilted downward,
The terminal e of the rotary switch 54 is connected to the connector E, and the connector P, the rotary switches 55 and 6
4 to the connector N. Since the floating coil is selectably connected between the connector N and the connector O, and the connector O is grounded via the rotary switch 65, the floating coil is eventually inserted between the middle point of the Y capacitor and the ground. Will be done.

When a common mode choke coil is selected, when switches 35 and 36 are turned down, switch 35 is connected to connector F via the terminal f of rotary switch 56, and three types of choke coils are further connected. Since the connector H is connected to the line through the connector H, the choke coil is inserted into the line. On the other hand, the switch 36 is connected to the connector G via the rotary switch 57, and further connected to the connector I via three types of choke coils. Since the connector I is connected to the line, the choke coil is inserted into the line. .
The pair of choke coils inserted in this way cancels each other's magnetic field and cancels common mode noise (noise conducting both lines equally).

When selecting a differential mode choke coil, for example, when the switch 41 is tilted downward, the switch 41 is connected to the connector J via the j terminal of the rotary switch 60 and further connected to the connector J via the choke coil. K, and the connector K is connected to the line, so that a choke coil is inserted into the line.
The same is true for the differential mode choke neutral line.

In the above example, the case of a constant coil (inductance) has been described. Of course, a resistance unit having a plurality of types of resistance values may be provided, or a ferrite core unit may be mounted. .

[0024]

As described above, according to the present invention, the device of the present invention is inserted between the device under test and the pseudo power supply network for noise measurement, so that the device under test can be disassembled and soldered. The filter circuit selection and filter constants can be easily selected without having to perform the above steps, so that the work involved in selecting the filter circuits and constants can be greatly improved, and the selection work can be performed efficiently. . In addition, by mounting a leakage ammeter, it is possible to select a filter constant and perform an electrical safety test.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a conduction noise elimination filter constant selection device of the present invention.

FIG. 2 is a diagram showing a noise level regulation value of a household electric appliance.

FIG. 3 is an external view of an apparatus including a filter selection circuit.

FIG. 4 is a diagram illustrating an example of a filter selection circuit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Filter selection circuit, 2 ... Pseudo power supply network, 3 ... Spectrum analyzer, 4 ... Test device, 11, 14,
18 ... Y capacitor unit, 12, 15 ... X capacitor unit, 13 ... Common mode choke coil unit, 16, 17 ... Differential mode choke coil unit, 19 ... Floating coil unit,
23 individual unit units, 30 to 44 switches, 50
~ 65 ... Rotary switch.

Claims (5)

[Claims] An apparatus for selecting a constant of a filter circuit for removing noise transmitted from a test apparatus through a line, comprising: a circuit element unit having a plurality of types of circuit elements constituting a filter circuit; and a circuit element unit bypassed. Or a selecting means for selecting an element having a predetermined constant from the circuit element unit, and a display means for displaying the selected circuit and circuit element. And a conduction noise elimination filter constant selecting device. 2. The apparatus according to claim 1, wherein said circuit element unit is detachable and replaceable. 3. The apparatus according to claim 1, further comprising a leakage ammeter so as to select a filter constant and perform an electrical safety test. 4. The apparatus according to claim 1, further comprising an external terminal for attaching an individual component. 5. The circuit according to claim 5, wherein the display means is a selected circuit,
2. The apparatus according to claim 1, wherein the circuit component is illuminated with a lamp and displayed.