KR101776213B1 - An apparatus for emi reduction of cooling fan controller - Google Patents

Abstract

In the present invention, an EMI reduction device on the DC power input side for reducing EMI CE noise, an EMI reduction device on the output side of a DC motor for reducing EMI RE noise in the AM band, and EMI RE noise in the DC motor are reduced An EMI reduction device is provided.
The EMI reduction device according to the present invention reduces the EMI noise in the operating frequency range due to the switching element of the PWM controller for controlling the DC motor of the automotive cooling fan and reduces the brush noise in the DC motor, It is possible to prevent the noise radiated from the other parts from adversely affecting the other parts, thereby providing a more reliable and safe electric vehicle component.

Description

TECHNICAL FIELD [0001] The present invention relates to an EMI reduction device for a cooling fan controller,

The present invention relates to an EMI (Electro-Magnetic Interference) reduction apparatus for a cooling fan controller, and more particularly, to an electromagnetic interference (EMI) reduction apparatus for a cooling fan controller, To an EMI reduction device for reducing EMI.

In accordance with the development of the automobile industry, the transition to a highly efficient and environmentally friendly automobile era incorporating environment and energy technology is rapidly progressing, and accordingly, efforts are being made to improve the fuel efficiency of automobiles in the automobile industry.

In accordance with this tendency, improvements have been made on automotive electric equipment to realize environment-friendly and high fuel efficiency characteristics. In particular, in the case of a cooling fan motor driven by an automobile battery, Research is continuing.

On the other hand, there are general DC motors, stepping motors and BLDC motors applied to automobiles. Of these, DC motors account for more than 95% of all motors used. DC motor is applied to the cooling fan. PWM (Pulse Width Modulation) method is generally used for speed control of DC motor. In order to increase the efficiency of motor drive system which consumes a lot of energy, If the overall motor efficiency increases by 1%, the power generation capacity of 1.5 nuclear power plants can be reduced. In addition, the speed control of the conventional cooling fan can be achieved only by adjusting the speed of the four stages by applying the variable resistance. However, in recent years, fine control has been required to improve the efficiency. For this purpose, the PWM inverter was applied instead of the conventional variable resistance method, but the problem of ensuring the electromagnetic compatibility was raised.

The PWM control method converts the DC output from the battery to AC waveform through time-based switching and power semiconductor control. It can control the speed and torque of the motor through DC-to-AC converter. have. In other words, the DC supply voltage of the battery is applied to the DC motor during the on-time using the switch of the battery, and the DC supply voltage is not applied to the DC motor during the off-time to control the speed of the motor . However, the PWM control method basically controls the energy transfer efficiency by switching, and it involves an unnecessary RFI (Radio Frequency Interference) due to the operation of the switch. Unlike an ideal switch, a switching device has electromagnetically undesirable factors such as switching loss and inrush current in practical switches because it performs a physical operation to block or flow the charge.

In other words, in the PWM control method, electromagnetic wave radiation and conduction noise are inevitably generated. In addition, as the number of electrical parts used in the vehicle increases, the electric power demand also increases and the amount of energy to be converted increases. Therefore, Since noise is generated, a solution is needed. In particular, the high frequency band signal has a good linearity, but does not cause a problem to the system because the energy amount is not large. However, the low frequency band signal has a large energy amount and low linearity, so it is likely to affect other components in the system.

Accordingly, it is necessary to reduce the radiation noise in the operating frequency range due to the switching of the switching device of the PWM controller for controlling the DC motor of the cooling fan. Therefore, it is necessary to design an EMI reduction device for the PWM controller.

In order to solve the above problems, the present invention reduces EMI noise in an operating frequency range caused by a switching element of a PWM controller for controlling a DC motor of a car cooling fan, And it is an object of the present invention to provide an EMI reduction device for a car cooling fan controller that can prevent adverse effects.

According to an aspect of the present invention, there is provided an EMI reduction apparatus comprising: a PWM (Pulse Width Modulation) controller for controlling an automobile cooling fan; an EMI (Electro-Magnetic Interference An EMI reduction device for reducing noise, comprising: a first terminal coupled to a direct current (DC) power source; A second terminal connected to ground; An inductor having both ends connected to the first terminal and the third terminal, respectively; First to fourth capacitors having opposite ends connected to the first terminal and the second terminal, respectively; And fifth to seventh capacitors having both ends connected to the third terminal and the second terminal, respectively.

In the EMI reduction apparatus according to an embodiment of the present invention, the second to fourth capacitors may have the same capacitance value, and the fifth and sixth capacitors may be configured to have the same capacitance value .

Meanwhile, an EMI reduction device according to an embodiment of the present invention includes a pulse width modulation (PWM) controller for controlling an automobile cooling fan, a radiating emission (RE) type EMI (Electro-Magnetic Interference) ) Comprising: a first terminal connected to a positive terminal of a direct current (DC) motor; A second terminal connected to the negative terminal of the direct current (DC) motor; A third terminal connected to the switching element; An inductor whose both ends are connected to the second terminal and the third terminal; And first to fourth capacitor groups having both ends connected to the first terminal and the second terminal, wherein the first to fourth capacitor groups are each formed by connecting two capacitors in series.

In the EMI reduction apparatus according to an embodiment of the present invention, the inductor may be a troidal type inductor, and two capacitors connected in series constituting the first to fourth capacitor groups may have the same capacitance value . ≪ / RTI >

An EMI reduction device according to an embodiment of the present invention may include a radiated emission (RE) type EMI (Electro-Magnetic Interference) noise in a PWM (Pulse Width Modulation) controller for controlling an automobile cooling fan An EMI reduction device for reducing an amount of electromagnetic interference (EMI), comprising: a first terminal connected to a negative terminal of a direct current (DC) motor; A second terminal connected to the switching element; A first inductor having both ends connected to the second terminal and the third terminal; A second inductor having both ends connected to the third terminal and the first terminal; A fourth terminal connected to ground; First to fifth capacitors having opposite ends connected to the third terminal and the fourth terminal; And sixth to tenth capacitors having both ends connected to the first terminal and the fourth terminal.

In the EMI reduction apparatus according to an embodiment of the present invention, the first inductor and the second inductor may have the same inductance value, and the fifth and tenth capacitors may have the same capacitance value. Lt; / RTI >

An EMI reduction device according to an embodiment of the present invention is an EMI (Electro-Magnetic Interference) reduction device for reducing brush noise in a DC motor for rotating a car cooling fan, A first terminal connected to a positive terminal of the DC motor and a first terminal of the brush; A second terminal connected to a negative terminal of the DC motor and a second terminal of the brush; A first capacitor having both ends connected to the first terminal and the second terminal; A second capacitor having one end connected to the first terminal and the other end grounded through a metal housing of the DC motor; And a third capacitor having one end connected to the second terminal and the other end grounded through a metal housing of the DC motor.

In the EMI reduction apparatus according to an embodiment of the present invention, the first capacitor to the third capacitor may have the same capacitance value, and the first capacitor to the third capacitor may be connected to each other without a stub, .

The technique disclosed in the present invention can have the following effects. It is to be understood, however, that the scope of the disclosed technology is not to be construed as limited thereby, as it is not meant to imply that a particular embodiment should include all of the following effects or only the following effects.

The EMI reduction device according to the present invention reduces the EMI noise in the operating frequency range due to the switching elements of the PWM controller for controlling the DC motor of the automotive cooling fan and reduces the brush noise inside the DC motor, It is possible to prevent the noise radiated from the other parts from adversely affecting the other parts, thereby providing a more reliable and safe electric vehicle component.

1 is a cooling fan system for a vehicle using a DC motor to which the EMI reduction device of the present invention is applied.
2 shows an existing circuit diagram on the battery power input end side.
3 is a circuit diagram of an EMI reduction apparatus for improving EMI noise according to the present invention.
4 and 5 show EMI test results of an EMI reduction apparatus for improving EMI CE noise according to the present invention.
6 shows an existing circuit diagram on the output stage side to the DC motor.
7 and 8 are circuit diagrams of an EMI reduction apparatus for improving EMI RE noise according to the present invention.
9 and 10 show EMI test results of an EMI reduction device for improving EMI RE noise according to the conventional circuit and the present invention, respectively.
11 shows an internal structure of a general DC motor.
12 shows the brush noise discharge path of the DC motor.
13 shows a circuit diagram in which X-Cap and Y-Cap are applied to the DC motor side.
14 shows a case where an X2Y filter is applied to the DC motor side.
Fig. 15 shows a Y-cap applied to a metal housing of a DC motor in order to apply an X-cap and a Y-cap to the DC motor side.
16 and 17 show the results of the brush noise test of the TPMS band before and after the improvement, respectively.

For the embodiments of the invention disclosed herein, specific structural and functional descriptions are set forth for the purpose of describing an embodiment of the invention only, and it is to be understood that the embodiments of the invention may be practiced in various forms, The present invention should not be construed as limited to the embodiments described in Figs.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms may be used for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprise", "having", and the like are intended to specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, , Steps, operations, components, parts, or combinations thereof, as a matter of principle.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be construed as meaning consistent with meaning in the context of the relevant art and are not to be construed as ideal or overly formal in meaning unless expressly defined in the present application .

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

A PWM (Pulse Width Modulation) controller is usually used to control a cooling fan of an automobile. In this case, electromagnetic interference (EMI) is generated due to the use of a switching element. Such electromagnetic interference also affects other electric parts of the vehicle, which may cause malfunctions and deteriorate energy efficiency. Therefore, it is very important to reduce the influence of such EMI.

Electro-Magnetic Interference (EMI) is a type of electromagnetic wave radiated from an electric / electronic device that interferes with the electromagnetic receiving function of other devices and is divided into Conducted Emission (CE) and Radiated Emission (RE) . Among them, the conductive radiation (CE) is transmitted through a medium such as a signal line or a power line, and mainly occurs in a circuit of 30 MHz or less. Radiation radiation (RE) is an electromagnetic wave noise It occurs mainly in circuits above 30 MHz. In order to reduce the EMI noise, methods such as designing an EMI filter by finding a radiation source of an electromagnetic wave, or efficient frame grounding are used.

The present invention provides an apparatus for reducing EMI CE and RE noise generated in a cooling fan for an automobile, and FIG. 1 shows a cooling fan system 100 for a vehicle using a DC motor to which the EMI reduction apparatus of the present invention is applied . It consists of a power cable 101, a PWM control board 102, a DC motor cable 103, and a DC motor 104.

As a result of examining the radiation characteristic of each part in the cooling fan system 100 for a vehicle, the power cable 101 is connected to the EMI CE noise path The PWM control board 102 becomes a radiation source of PWM CE and RE noise and the DC motor cable 103 becomes a PWM multiplication RE noise path and a DC motor brush RE noise path, It was judged to be a radiation source of brush CE and RE noise.

Accordingly, the present invention provides an EMI reduction device on the DC power input side for reducing EMI CE noise, an EMI reduction device on the output side to the DC motor for reducing EMI RE noise in the AM band, An EMI reduction device for reducing noise is provided, and details thereof are as follows.

2 is an existing circuit diagram on the battery power input end side, and FIG. 3 illustrates an improvement of EMI CE noise according to an embodiment of the present invention. And the capacitor filter portion is improved. 3, an EMI reduction device for improving EMI noise according to an exemplary embodiment of the present invention includes a first terminal connected to a DC power source, a second terminal connected to a ground, An inductor L1 connected to the first terminal and the third terminal, first to fourth capacitors C101, C701, C702, and C703 having both ends connected to the first terminal and the second terminal, And fifth to seventh capacitors (EC2, EC3, C70) connected to the third terminal and the second terminal. 4 and 5 are diagrams illustrating EMI levels of EMI reduction devices for improving EMI CE noise according to the present invention, respectively. Referring to FIG. 4 and FIG. 5, Test results are shown.

4 and FIG. 5, it can be seen that the noise level of each frequency band in FIG. 5 is reduced compared to the noise level of each frequency band in FIG. 4 as a result of the EMI CE test. That is, the level of the AM band PWM (20 kHz harmonic) noise in the sub-2 MHz band is reduced, and the level of the ARISU chip operating frequency multiplication noise in the band over 30 MHz is also reduced. As described above, the EMI reduction apparatus for improving EMI CE noise according to an embodiment of the present invention reduces the noise level for each frequency band through the above-described circuit configuration. However, in order to obtain such an improved EMI reduction effect Since the CE measurement value can be changed according to the load inductance characteristic of the DC motor, it may be necessary to perform tuning by changing the capacitance value of the capacitor according to the characteristics of a general filter.

6 is an existing circuit diagram of an output stage of a DC motor, and FIG. 6 is a block diagram of an EMI reducing apparatus according to an embodiment of the present invention. 7 and 8 show a circuit diagram of an EMI reduction apparatus for improving EMI RE noise according to the present invention.

In other words, referring to FIG. 7, in the EMI reduction device of the output stage to the DC motor for reducing the EMI RE noise in the AM band according to the embodiment of the present invention, A second terminal connected to the negative terminal of the DC motor, a third terminal connected to the switching element (MOS-FET), an inductor L702 having both ends connected to the second terminal and the third terminal, A first capacitor group of C708 and C709, a second capacitor group of C710 and C711, a third capacitor group of C712 and C713, and a third capacitor group of C714 and C715 connected to the first terminal and the second terminal A fourth capacitor group), and each of the first to fourth capacitor groups includes two capacitors connected in series.

7 may generate heat, it is preferable to use a troidal inductor as the inductor L702, and it is preferable to apply a saturation current standard of about 40 to 50 A or more.

In addition, an EMI reduction device on the output stage side to a DC motor for reducing EMI RE noise in the AM band according to an embodiment of the present invention can be configured as shown in FIG. 8, A first inductor L702 having both ends connected to the second terminal and the third terminal, a first terminal connected to the first terminal and a second terminal connected to the third terminal, A second inductor L703 connected to the first terminal, a fourth terminal connected to the ground, first to fifth capacitors C708 to C712 having both ends connected to the third terminal and the fourth terminal, And sixth to tenth capacitors C713 to C717 connected to the first terminal and the fourth terminal. Accordingly, in the EMI reduction apparatus of Fig. 8, the voltage on the negative terminal side of the DC motor can stably operate at a voltage of 13V or less on the positive terminal side. However, in order to obtain the improved EMI reduction effect, the CE measurement value may be changed according to the load inductance characteristic of the DC motor. Therefore, it may be necessary to perform the tuning operation by changing the capacitance value of the capacitor accordingly.

In the EMI reduction apparatus of FIG. 8, the saturation current standard of the first inductor L702 and the second inductor L703 is preferably about 30 to 35 A, and a troidal inductor and an SMD type Both inductors are applicable. However, when the size is not excessively large, it is preferable to apply a troidal type inductor in consideration of heat generation.

9 and 10 show EMI test results of an EMI reduction apparatus for improving EMI RE noise according to an embodiment of the present invention. The EMI test result of the EMI reduction apparatus according to the embodiment of FIG. 10 shows that the harmonic energy of 200 kHz or more is reduced . Therefore, it can be seen that the EMI reduction noise level of the AM band is reduced in the EMI reduction apparatus according to an embodiment of the present invention.

Next, an EMI reduction device for reducing EMI RE noise in the DC motor will be described. 11 shows an internal structure of a general DC motor. The power supply terminals M + and M- are in contact with a commutator through a brush. In order to change the polarity during rotation, There is a discontinuous section as shown in Fig. As the power supplied to the commutator in contact with the brush is instantaneously cut off in the discontinuous section, the current stored in the coil is instantaneously discharged, thereby generating a spark-like noise such as an arc discharge This is called brush noise.

The radiation of the brush noise will be described with reference to Fig. FIG. 12 shows a brush noise discharge path of the DC motor. Referring to FIG. 12, the brush noise generated in the DC motor radiates directly into the air in the form of a radiated emission (RE) And is emitted in the form of Conducted Emission (CE) to the power supply terminals (M +, M-). In this case, when the housing of the DC motor is formed of a metal housing as shown in the lower part of FIG. 12 as compared with the case where the non-metal parts (plastic caps) are mixed as shown in the upper drawing of FIG. 12, Direct radiation radiation is shielded and only conductive radiation to the power supply terminals (M +, M-), which is the power supply line, is generated. Here, the motor cable connected to the power supply terminals M + and M- serves as an antenna for radiating brush noise. Therefore, brush noise should be reduced inside the DC motor.

In order to reduce the brush noise in the DC motor, in the EMI reduction device for reducing the brush noise according to the embodiment of the present invention, the X-Cap and Y-Cap are not stub- And its circuit diagram is shown in Fig.

13, an EMI reduction device for reducing brush noise according to an embodiment of the present invention includes a first terminal M + of a DC motor and a first terminal M + of a brush connected to a first terminal + A second terminal connected to a negative terminal M- of the DC motor and a second terminal Brush of the brush, a first capacitor X-cap having both ends connected to the first terminal and the second terminal, , A second capacitor (Y-cap) having one end connected to the first terminal and the other end grounded through a metal housing of the DC motor, and one end connected to the second terminal and the other end connected to the DC motor And a third capacitor (Y-cap) grounded through a metal housing of the capacitor. As described above, the parasitic inductance component can be minimized by applying the X-Cap and Y-Cap without a stub at the final output stage inside the motor.

Meanwhile, in the EMI reduction apparatus for reducing brush noise according to an embodiment of the present invention, instead of applying X-Cap and Y-Cap, an X2Y filter (X2Y attenuator) .

15 shows a Y-cap applied to a metal housing of a DC motor in order to apply an X-cap and a Y-cap to the DC motor. As shown in FIG. 15, When X-Cap and Y-Cap are applied at the output stage, it is preferable to apply it to the motor and cable connection end through small size PCB.

FIG. 16 shows a brush noise test result of a TPMS (Tire Pressure Monitoring System) band by a conventional DC motor, FIG. 17 shows a DC motor with an EMI abatement device for reducing brush noise according to an embodiment of the present invention The results of the brush noise test of the TPMS band of FIG. That is, when comparing the noise levels in the TPMS frequency band of FIGS. 16 and 17, it can be seen that the noise level of the DC motor to which the EMI reduction device for reducing brush noise according to an embodiment of the present invention is applied is significantly reduced have. As a result, the influence of the brush noise of the DC motor on the other electric parts is reduced, so that it is possible to provide a more reliable and safe electric vehicle component.

As described above, the EMI reduction apparatus according to the present invention reduces the EMI noise in the operating frequency range due to the switching elements of the PWM controller for controlling the DC motor of the automotive cooling fan, and reduces the brush noise inside the DC motor It is possible to prevent the noise emitted from the cooling fan side of the automobile from adversely affecting other components, thereby providing a more reliable and safe automotive electric component.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. That is, within the scope of the present invention, all of the components may be selectively coupled to one or more of them. In addition, although all of the components may be implemented as one independent hardware, some or all of the components may be selectively combined to perform a part or all of the functions in one or a plurality of hardware. As shown in FIG. The codes and code segments constituting the computer program may be easily deduced by those skilled in the art. Such a computer program is stored in a computer readable storage medium, readable and executed by a computer, thereby realizing an embodiment of the present invention. As a storage medium of the computer program, a magnetic recording medium, an optical recording medium, or the like can be included.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims (12)

An EMI reduction device for reducing EMI (Electro-Magnetic Interference) noise of a radiated emission (RE) type in a PWM (Pulse Width Modulation) controller for controlling a cooling fan of an automobile,
A first terminal connected to a negative terminal of a direct current (DC) motor;
A second terminal connected to the switching element;
A third terminal disposed between the first terminal and the second terminal;
A first inductor having both ends connected to the second terminal and the third terminal;
A second inductor having both ends connected to the third terminal and the first terminal;
A fourth terminal connected to ground;
First to fifth capacitors having opposite ends connected to the third terminal and the fourth terminal;
And sixth to tenth capacitors having both ends connected to the first terminal and the fourth terminal,
Wherein the first to third capacitors have the same capacitance value, the fourth capacitor has a capacitance value smaller than that of the first to third capacitors, the sixth to eighth capacitors have the same capacitance value, The fifth capacitor has a smaller capacitance value than the first to fourth capacitors, the tenth capacitor has a capacitance value smaller than that of the sixth to ninth capacitors,
Wherein a saturation current standard of the first inductor and the second inductor is in the range of 30 A to 35 A, and a Troy type inductor is applied in consideration of heat generation. The method according to claim 1,
Wherein the first inductor and the second inductor have the same inductance value. The method according to claim 1,
Wherein the fifth capacitor and the tenth capacitor have the same capacitance value.


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