KR100691785B1 - Circuit for reducing electromagnetic interference in DC moter - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave attenuation circuit for a dc motor, wherein a common mode coil, a differential mode coil, and a capacitor are used to attenuate the electromagnetic wave noise generated when the dc motor is driven. It can prevent malfunctions and control the DC motor stably.

DC Motor, DC Motor, DC MOTOR, Electromagnetic Wave, Electromagnetic Wave, Electromagnetic Wave, EMI, Noise Filter, Noise Filter, Filter

Description

Circuit for reducing electromagnetic interference in DC motors {Circuit for reducing electromagnetic interference in DC moter}

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to

1 is a circuit diagram showing an electromagnetic attenuation circuit according to the prior art.

Fig. 2 is a circuit diagram showing an electromagnetic wave attenuation circuit in the case of employing a four brush type motor in the prior art.

3 is a circuit diagram illustrating an electromagnetic attenuation circuit according to a preferred embodiment of the present invention.

FIG. 4 is a circuit diagram showing an electromagnetic attenuation circuit in the case of employing a four-brush motor according to another embodiment of the present invention.

5 is a graph of measuring electromagnetic interference noise in an electromagnetic attenuation circuit according to a first comparative example of the related art.

6 is a graph of measuring electromagnetic interference noise in an electromagnetic attenuation circuit according to a second comparative example of the related art.

7 is a graph of measuring electromagnetic interference noise in an electromagnetic attenuation circuit according to a third comparative example of the related art.

8 is a graph of measuring electromagnetic interference noise in an electromagnetic attenuation circuit according to a fourth comparative example of the related art.

9 is a graph of measuring electromagnetic interference noise in an electromagnetic attenuation circuit according to a first embodiment of the present invention.

FIG. 10 is a graph measuring electromagnetic interference noise in an electromagnetic attenuation circuit according to a second exemplary embodiment of the present invention.

FIG. 11 is a graph measuring electromagnetic interference noise in an electromagnetic attenuation circuit according to a third exemplary embodiment of the present invention.

12 is a graph of measuring electromagnetic interference noise in an electromagnetic attenuation circuit according to a fourth exemplary embodiment of the present invention.

<Description of main reference numerals in the drawings>

20 ... Common mode noise filter 30 ... Differential mode noise filter

40 ... Arc discharge noise filter 50 ... Common mode noise filter

60 ... Differential Mode Noise Filter 70 ... Arc Discharge Noise Filter

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave attenuating circuit for a DC motor, and more particularly to a circuit capable of reducing electromagnetic noise generated in a common mode and a differential mode when a DC motor is driven.

In general, electrical and electronic devices composed of electrical and electronic circuits, when disposed in close proximity to each other, generate electromagnetic noise as a result of electrical or electromagnetic interactions. These electromagnetic waves affect the operation and control of electrical and electronic equipment, and may also cause malfunctions of the electrical and electronic equipment.

In particular, since parts such as permanent magnets, coils, and brushes are built in the motor, many electromagnetic noises are generated by arc discharge of the brush due to the rotation of the motor. Therefore, much research has been conducted on the design of the motor driving circuit that can reduce the electromagnetic noise generated in the motor.

Electromagnetic electromagnetic noise generated in electric and electronic devices includes largely conducted noise that is conducted through power lines and radiated noise that is radiated into the air in the form of electromagnetic waves. On the other hand, conducted noise is further divided into common mode noise caused by a common mode current component and differential mode noise caused by a differential mode current component.

Referring to FIG. 1, in general, a conventional method for reducing electromagnetic noise generated in a motor is mainly performed in a differential mode using coils L1 and L2 and a capacitor C ₁ used in a differential mode. It reduces the generated electromagnetic noise. Here, the capacity of the coil (L1, L2) and the capacitor (C ₁ ) is appropriately adjusted according to the rated voltage and current of the motor used. In addition, in motors where conduction noise is not a problem, coils L1 and L2 may be omitted or capacitor C ₁ may be omitted, that is, no attenuation circuit is provided.

2 is basically the same as the prior art illustrated in FIG. 1 except that a four-brush type motor is used as a conventional example.

However, when designing the attenuation circuit using the differential mode coil (L1, L2) and the capacitor (C ₁ ) as shown in Figures 1 and 2, the electrical presented by the manufacturer of the electronic device using the motor In many cases, the electromagnetic wave noise standards or international standards were not met.

The present invention has been made to solve the above problems, to provide a circuit that satisfies a predetermined standard by reducing the electromagnetic noise of the DC motor driving circuit using a common mode coil, a differential mode coil and a capacitor. have.

In order to achieve the above object, the electromagnetic attenuation circuit according to the present invention includes a matching capacitor for matching an impedance between a power supply and a power input terminal of a motor in a DC motor driving circuit; A common mode coil connected in parallel to the matching capacitor, a first capacitor connected between the positive pole of the common mode coil and ground, and a first capacitor connected between the negative pole of the common mode coil and ground; A common mode noise filter having two capacitors; A differential mode noise filter including a third capacitor connected in parallel to the common mode noise filter output and a differential mode coil connected to each end of the third capacitor; And an arc discharge noise filter connected between the differential mode noise filter and a power input terminal of the motor to absorb arc discharge noise generated from a brush of the motor.

It is preferable that the first capacitor and the second capacitor have a capacitance of 470 [Hz] to 2200 [kHz], and the third capacitor preferably has a capacitance of 1.0 [μF] to 3.3 [μF].

The common mode coil is preferably made of a coil capable of being formed as a waste including a toroidal coil, a U-type coil or an SQ-type coil, so as to form a waste path, and the core of the common mode coil is made of a ferrite magnetic material. Do.

In addition, the core of the differential mode coil is preferably made of a ferrite magnetic material.

Preferably, the arc discharge noise filter may include a capacitor, and more preferably, the capacitance of the capacitor may be 1.0 [μF] to 3.3 [μF].

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

3 is a circuit diagram illustrating an electromagnetic attenuation circuit of a DC motor driving circuit according to a preferred embodiment of the present invention. 3, the electromagnetic wave attenuation circuit according to an embodiment of the present invention is common mode noise filter is connected in parallel to the matching capacitor (C _10), the matching capacitor (C ₁₀₎ to match the impedance present in the circuit ( 20), the differential mode noise filter 30 is connected to the output of the common mode filter 20, the differential mode noise filter 30 and the arc discharge noise filter 40 and the arc discharge noise connected between the power input terminal of the motor It is provided with a two-brush motor M1 connected to the output end of the filter 40.

The matching capacitor C ₁₀ matches the impedance of the motor M1 itself with the impedance of each filter 20, 30, 40 and applies it to the common mode noise filter 20. Here, the capacitance of the matching capacitor (C ₁₀ ) is appropriately adjusted according to the impedance of the motor (M1) itself and the impedance of each filter (20, 30, 40), preferably of the capacitor adopted as the matching capacitor (C ₁₀ ) Capacitance may be 0.1 [μF] to 1.0 [μF].

The common mode noise filter 20 includes a common mode coil L ₂₀ connected across the matching capacitor C ₁₀ , and a first capacitor C connected between the positive pole of the common mode coil L ₂₀ and a ground. ₂₁ ) and a second capacitor C ₂₂ connected between the negative pole of the common mode coil L ₂₀ and the ground. When the first capacitor C ₂₁ and the second capacitor C ₂₂ are connected to the ground, the first capacitor C ₂₁ and the second capacitor C ₂₂ may be connected to the ground of the circuit board having the attenuation circuit. Is preferably connected to.

The common mode coil L ₂₀ blocks the inflow of the common mode high frequency generated from the motor by using counter electromotive force, and the first capacitor C ₂₁ and the second capacitor C ₂₂ have high impedance at a low frequency due to frequency characteristics. It prevents the inflow of current by supplying the current, and at the high frequency, the impedance is lowered, so that the high frequency present in the common mode noise is supplied to ground to reduce the generation of the high frequency.

Common mode coil (L ₂₀ ) is preferably made of a coil that can be formed as a waste containing a toroidal coil, a U-type coil or an SQ-type coil in order to block the inflow of the common mode high frequency.

In addition, the core of the common mode coil (L ₂₀ ) is preferably made of a ferrite magnetic material that can accommodate high frequency absorption.

The differential mode noise filter 30 may include a third capacitor C ₃₁ connected in parallel to both ends of the first capacitor C ₂₁ and the second capacitor C ₂₂ , and both terminals of the third capacitor C ₃₁ . And differential mode coils L ₃₁ and L ₃₂ connected to + and-).

The differential mode coils L ₃₁ and L ₃₂ suppress the differential mode high frequency introduced from both terminals of the motor through the counter electromotive force, and the third capacitor C ₃₁ has two differential mode coils L ₃₁ and L ₃₂ . L ₃₂ ) absorbs the high frequency generated by the imbalance of the output frequency.

The arc discharge noise filter 40 includes a fourth capacitor C ₄₁ . Brush-type motor M1 having a brush and a commutator tends to cause arc discharge due to air insulation breakdown between the brush and commutator. As a result, the electromagnetic interference of the electromagnetic waves is generated in the motor M1, and the fourth capacitor C ₄₁ absorbs the electromagnetic interference generated by the arc discharge.

Here, the inductance used for the common mode coil L ₂₀ and the differential mode coils L ₃₁ and L ₃₂ is appropriately adjusted according to the rated voltage and current of the motor and also according to the electromagnetic noise. It is preferable that it is 4 [μH] or more for blocking.

Fig. 4 is a circuit diagram showing the electromagnetic wave attenuation circuit in the case of employing a four brush type motor. 4 differs from that of adopting the 4 brush type motor M2 instead of the 2 brush type motor M1 of FIG. 3, and the basic components and circuit operations of the circuit are the same as those of FIG. The same components as those in Fig. 3 are given the same reference numerals and the detailed description thereof is omitted.

The four brush type motor M2 of FIG. 4 is provided with four input terminals. As a result, one fourth capacitor is provided at each terminal of the four-brush type motor M2, and thus, between the differential mode coils L ₃₁ and L ₃₂ and both terminals (+,-) of the four brush type motor M2. Four fourth capacitors C ₄₁₁ , C ₄₁₂ , C ₄₁₃ and C ₄₁₄ are connected in parallel.

On the other hand, it is preferable that the arc discharge noise filters 40 and 70 are most closely connected to the brushes of the motor, and the arc discharge noise filter 70 is shown in FIG. 4 in a circuit for driving the motor employing at least four brushes. Is preferably connected in parallel between each power input terminal of the motor M2 and the differential mode noise filter 60, respectively.

Then, it will be seen through the experimental example that can be attenuated by the electromagnetic wave generated when the motor driving through the electromagnetic attenuation circuit according to the present invention.

Comparative Example 1

As shown in FIG. 1, the electromagnetic attenuation circuit used in Comparative Example 1 includes a capacitor C ₁ , coils L 1 and L 2 connected to the capacitor C ₁ , and 2 connected to the coils L 1 and L 2. It consists of the brush-type motor M1. Impedances of the elements C ₁ , L1, and L2 provided in the electromagnetic attenuation circuit are as follows.

C ₁ = 0.47 [μF], L1 = 4.4 [μH], L2 = 4.4 [μH]

5 shows the results of measuring the electromagnetic waves based on the standards suggested by Hyundai through the design of the electromagnetic attenuation circuit having the two-brush type motor M1 as described above. In FIG. 5, the solid line indicates the reference of the electromagnetic waves presented by Hyundai Electronics, and the wave form indicates the measurement result of Comparative Example 1. FIG.

Comparative Example 2

The electromagnetic attenuation circuit used in Comparative Example 2 is the same as the circuit used in Comparative Example 1 except that the four-brush type motor M2 is provided as shown in FIG. 2, and is provided in the electromagnetic attenuation circuit. Impedance of each of the elements (C ₁ , L1, L2) is as follows.

C ₁ = 0.47 [μF], L1 = 4.4 [μH], L2 = 4.4 [μH]

FIG. 6 shows the results of measuring the electromagnetic waves based on the standards suggested by Hyundai through the design of the electromagnetic attenuation circuit having the four-brush type motor M2 as described above. In FIG. 6, the solid line indicates the electric magnetic wave standard presented by Hyundai Electronics, and the wave form indicates the measurement result of Comparative Example 2. FIG.

Comparative Example 3

Comparative Example 3 was equipped with a device having the same impedance and the same circuit as in Comparative Example 1 to measure the electric magnetic waves on the basis presented by Daewoo Electronics, the results are shown in FIG. In FIG. 7, the solid line indicates the electromagnetic wave standard presented by Daewoo Electronics, and the wave form indicates the measurement result of Comparative Example 3. FIG.

Comparative Example 4

Comparative Example 4 was equipped with a device having the same impedance and the same circuit as in Comparative Example 2 to measure the electric magnetic waves based on the standards presented by Daewoo Electronics, the results are shown in FIG. In FIG. 8, the solid line indicates the reference of the electromagnetic waves presented by Daewoo Electronics, and the wave form indicates the measurement result of Comparative Example 4. FIG.

Referring to Comparative Examples 1 to 4, it can be seen that the electromagnetic wave attenuation circuit implemented according to the prior art does not satisfy the electromagnetic wave standards proposed by the electrical and electronic device manufacturers.

Example 1

Example 1 Electrical used for magnetic wave attenuation circuit as shown in Figure 3, a matching capacitor (C _10), a matching capacitor (C ₁₀₎ a common mode coil (L ₂₀₎ is connected in parallel, a common mode coil (L ₂₀ ) the first capacitor C ₂₁ connected between the positive pole of the positive pole and the ground, the second capacitor C ₂₂ connected between the negative pole of the common mode coil L ₂₀ and the ground; Differential mode coils connected to both terminals (+,-) of the third capacitor (C ₃₁ ) and the third capacitor (C ₃₁ ) connected in parallel to the one capacitor (C ₂₁ ) and the second capacitor (C ₂₂ ) L ₃₁ and L ₃₂ , a fourth capacitor C ₄₁ connected to the rear ends of the differential mode coils L ₃₁ and L ₃₂ , and a two-brush type motor M1.

The impedances of the elements C ₁₀ , C ₂₁ , C ₂₂ , C ₃₁ , C ₄₁ , L ₂₀ , L ₃₁ and L ₃₂ provided in the electromagnetic attenuation circuit are as follows.

C ₁₀ = 0.47 [μF], C ₂₁ = 470 [㎊], C ₂₂ = 470 [㎊], C ₃₁ = 2.2 [μF], C ₄₁ = 2.2 [μF]

L ₂₀ = 90 [μH], L ₃₁ = 8.5 [μH], L ₃₂ = 8.5 [μH]

FIG. 9 shows the results of measuring the electromagnetic waves based on the standards suggested by Hyundai Electronics through the design of the electromagnetic attenuating circuit including the two-brush type motor M1. In FIG. 9, solid lines indicate electric electromagnetic waves presented by Hyundai Motor and Kia Motors, and waveforms indicate measurement results of the first embodiment.

Example 2

As shown in FIG. 4, the electromagnetic attenuation circuit used in Example 2 is provided with a four-brush type motor M2 and a fourth capacitor C ₄₁₁ , C ₄₁₂ , C ₄₁₃ , and C ₄₁₄ . And the same circuit used in Example 1.

The impedance of each element (C ₁₀ , C ₂₁ , C ₂₂ , C ₃₁ , C ₄₁₁ , C ₄₁₂ , C ₄₁₃ , C ₄₁₄ , L ₂₀ , L ₃₁ , L ₃₂ ) included in the electromagnetic attenuation circuit is as follows. .

C ₁₀ = 0.47 [μF], C ₂₁ = 470 [㎊], C ₂₂ = 470 [㎊], C ₃₁ = 3.3 [μF], C ₄₁₁ = C ₄₁₂ = C ₄₁₃ = C ₄₁₄ = 2.2 [μF], L ₂₀ = 90 [μH], L ₃₁ = 8.5 [μH], L ₃₂ = 8.5 [μH]

The results of measuring the electromagnetic waves based on the standards suggested by Hyundai through the design of the electromagnetic attenuating circuit provided with the four-brush type motor M2 are shown in FIG. 10. In FIG. 10, solid lines indicate electric electromagnetic waves presented by Hyundai Motor and Kia Motors, and waveforms indicate measurement results of the second embodiment.

Example 3

Example 3 was equipped with a device having the same impedance and the same circuit as in Example 1 to measure the electric magnetic waves by the standard proposed by Daewoo Electronics, the results are shown in FIG. In FIG. 11, the solid line indicates the electric magnetic wave reference suggested by Daewoo Motor, and the wave form indicates the measurement result of the third embodiment.

Example 4

Example 4 was equipped with a device having the same impedance and the same circuit as in Example 2 to measure the electric magnetic waves based on the criteria presented by Daewoo Electronics, the results are shown in FIG. In FIG. 12, the solid line indicates the electric magnetic wave standard suggested by Daewoo Motor, and the wave form indicates the measurement result of the fourth embodiment.

Referring to Examples 1 and 2, when the electromagnetic attenuation circuit is adopted in accordance with an embodiment of the present invention, the electromagnetic electromagnetic waves generated from the motor are significantly attenuated, and thus the electric electromagnetic standards proposed by Hyundai Motor and Kia Motors are used. It can be confirmed that it satisfies the present invention. Referring to Examples 3 and 4, it can be confirmed that the electromagnetic wave standards proposed by Daewoo Motors are satisfied.

Therefore, the capacitance of the first capacitor C ₂₁ and the second capacitor C _{22 included in} the electromagnetic attenuation circuit of the present invention preferably has a range of 470 [kW] to 2200 [kW], and the third It is preferable that the capacitances of the capacitor C ₃₁ and the fourth capacitors C ₄₁ , C ₄₁₁ , C ₄₁₂ , C ₄₁₃ , and C ₄₁₄ are 1.0 [μF] to 3.3 [μF].

In addition, the inductance of the common mode coil L ₂₀ is preferably in the range of 4 [μH] to 90 [μH], and the inductance of the differential mode coils L ₃₁ and L ₃₂ is 5 [μH] to 8.5 [μH] or less. It is preferable.

As described above, according to the present invention, by designing the electromagnetic wave attenuation circuit having a common mode coil, a differential mode coil and a capacitor, it is possible to effectively reduce the electromagnetic noise generated when driving the DC motor.

In addition, by reducing the electric electromagnetic wave noise generated when the DC motor is driven, it is possible to prevent the malfunction of the electrical and electronic equipment adopting the DC motor.

Claims (11)

In a DC motor drive circuit, A matching capacitor that matches the impedance of the circuit; A common mode coil connected in parallel to the matching capacitor, a first capacitor connected between a positive pole of the common mode coil and a ground, and a second capacitor connected between a negative pole of the common mode coil and a ground; A common mode noise filter having a capacitor; A differential mode noise filter including a third capacitor connected in parallel to the common mode noise filter output and a differential mode coil connected to each end of the third capacitor; And And an arc discharge noise filter connected between the differential mode noise filter and a power input terminal of the motor to absorb arc discharge noise generated from a brush of the motor. The method of claim 1, The matching capacitor has an electromagnetic attenuation circuit, characterized in that having a capacitance of 0.1 [μF] ~ 1.0 [μF]. The method of claim 1, The ground is an electromagnetic attenuation circuit, characterized in that connected to the motor body. The method of claim 1, And said first capacitor and said second capacitor have capacitances of 470 [Hz] to 2200 [Hz]. The method of claim 1, The third capacitor has an electromagnetic attenuation circuit, characterized in that having a capacitance of 1.0 [μF] ~ 3.3 [μF]. The method of claim 1, The common mode coil is an electromagnetic attenuation circuit, characterized in that consisting of a coil that can be formed as a waste containing a toroidal coil, a U-type coil or an SQ-type coil to form a waste path. The method of claim 1, And said common mode coil core is made of a ferrite magnetic material. The method of claim 1, The core of the differential mode coil is an electromagnetic interference attenuation circuit, characterized in that made of a ferrite magnetic material. The method of claim 1, The arc discharge noise filter is characterized in that it comprises a capacitor electro-magnetic wave attenuation circuit. The method of claim 9, The capacitor provided in the arc discharge noise filter has an capacitance of 1.0 [μF] to 3.3 [μF]. delete

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