WO2016202240A1

WO2016202240A1 - Electromagnetism-compatible filter

Info

Publication number: WO2016202240A1
Application number: PCT/CN2016/085711
Authority: WO
Inventors: 周德旺; 袁宝成; 柳朝华; 高喆; 刘晓录; 刘皞星
Original assignee: 联合汽车电子有限公司
Priority date: 2015-06-16
Filing date: 2016-06-14
Publication date: 2016-12-22
Also published as: CN104953802A

Abstract

Disclosed is an electromagnetism-compatible filter, which comprises a current-carrying conductor (1) and a plurality of capacitors (4), the capacitors are distributed at the periphery of the current-carrying conductor, one end of which is electrically connected to the current-carrying conductor through a first conductor (8), and the other end of which is electrically connected to a grounded end (7) of the filter through a second conductor (9); and the first conductor and the second conductor are both shaped like an annular plane. The filter has a simple structure, has a small number of the constituent elements, thereby being able to effectively reduce the costs and the size of the filter. The equivalent inductance of a plurality of capacitors is the parasitic inductance of a single capacitor divided by the number of the capacitors, and thus, the parasitic inductance of the capacitors is decreased; at the same time, the first conductor and the second conductor both being shaped like an annular plane can be equivalent to innumerable radial conductors, a magnetic field generated by each conductor can be counteracted, and thereby the parasitic inductance generated by the connecting conductors is decreased. The structure which is composed of the capacitors and the connecting conductors can effectively shield interference between the input and output of the filter, thus further improving filtering performance.

Description

Electromagnetic compatibility filter

Technical field

The invention relates to an automobile electronic device, and particularly belongs to an electromagnetic compatibility filter, which is used for a power electronic controller and a switching power supply module.

Background technique

With the continuous development of automotive electronic control technology, the number of electronic devices used in automobiles has increased greatly. The operating frequency of the circuit has gradually increased and the power has gradually increased. This has caused the working environment of the automobile to be filled with a large amount of electromagnetic waves, resulting in electromagnetic Interference problems are becoming more and more prominent, which affects the normal operation of electronic equipment, and damages the corresponding electrical components, causing immeasurable risks.

As one of the key components of the new energy vehicle, the DC/DC power module contained in the power electronic controller replaces the generator, which converts the DC input voltage of the high voltage battery into a low voltage DC voltage to supply the entire electrical component. According to the mechanism of the switching power supply, the output voltage of the DC/DC power supply module is not an ideal DC voltage. It is rich in high-order harmonics. If the switching frequency is 100KHz, the interference frequency can reach several hundred megahertz. These interferences pass. The low-voltage power supply network of the whole vehicle may directly interfere with the vehicle equipment such as the radio, or it may interfere with the equipment outside the vehicle through the radiation of the entire vehicle wiring harness, causing serious problems.

In order to reduce external interference, DC/DC power modules usually need to add filters to filter out high-frequency interference and retain DC voltage. The filter generally consists of two components, an inductor and a capacitor. The inductor is connected in series on the output line, and the capacitor is connected in parallel between the positive output and the negative output. Ideally, the impedance of the inductor is proportional to the frequency, which can turn on the DC voltage and block the AC voltage. The impedance of the capacitor is inversely proportional to the frequency, blocking the DC voltage and turning on the AC voltage. Therefore, ideally DC/DC The current generated by the DC voltage output of the power module reaches the load through the inductor and the positive output, and returns to DC/DC through the negative output. The current generated by the high-frequency interference voltage is directly along the DC/DC due to the blocking effect of the inductor and the conduction of the capacitor. The positive output, filter capacitor, and negative output return, so it does not propagate to the outside of the DC/DC power module.

According to the output current of the DC/DC power supply module, the output conductor of the power module can adopt a PCB trace or a copper bus structure. When PCB traces are used, since the PCB itself is a planar structure, an additional connection conductor is generally disposed on one side or both sides of the current-carrying conductor 1. 2, 6 Connected to the capacitor 4; when the copper row structure is used, the copper row is generally formed by cutting and bending a copper plate. Similar to the PCB, the conductors 2 and 6 connected to the capacitor 4 can only be arranged on one side or both sides, as shown in Fig. 1. Shown. Filters using these two structures propagate high-frequency interference to the outside, for the following reasons:

1) The capacitor 4 itself has parasitic inductance. At the same time, the connecting conductors 2 and 6 connecting the two ends of the capacitor to the positive output terminal and the negative output terminal also have a certain parasitic inductance, which causes the impedance of the capacitor at the high frequency to be too large to be effectively guided. Passing high frequency interference voltage;

2) Taking the capacitor as the reference point, the front positive output and the negative output conductor of the DC/DC power supply module circulate a large amount of interference current, and the rear conductor close to the DC/DC power supply module has a small interference current, and the front conductor directly passes through the space radiation. The rear conductor creates a lot of interference, causing the filter to fail.

technical problem

The technical problem to be solved by the present invention is to provide an electromagnetic compatibility filter, which can reduce the parasitic inductance of the capacitor and the connecting conductor, and solve the problem of mutual coupling of the front and rear conductors of the filter capacitor.

Technical solution

In order to solve the above technical problem, the electromagnetic compatibility filter provided by the present invention comprises a current carrying conductor and a plurality of capacitors. The capacitor is distributed on the outer circumference of the current carrying conductor, and one end of the capacitor is electrically connected to the current carrying conductor through the first conductor, and the capacitor is electrically connected. One end is electrically connected to the ground end of the filter through the second conductor.

Preferably, the distance between each capacitor and the current carrying conductor is equal.

Preferably, the capacitor is circumferentially distributed around the current carrying conductor.

In the above structure, the first conductor connecting the capacitor and the current carrying conductor has an annular planar shape.

In the above structure, the second conductor connecting the capacitor and the ground of the filter has an annular planar shape.

Preferably, the second conductor is a PCB board, and the first end surface of the PCB board is grounded, and the PCB board has a through hole through which the current carrying conductor passes, and the capacitor is distributed around the current carrying conductor. The second end of the PCB. The current-carrying conductor and the PCB board are electrically connected through a metal connecting member.

Beneficial effect

The invention is advantageous in that:

1) The present invention arranges a plurality of capacitors on the circumference of the current-carrying conductor, and the parasitic inductance of each capacitor itself is small, and the equivalent inductance of the plurality of capacitors is the parasitic inductance of the single capacitor divided by the number of capacitors, thus reducing the filter The parasitic inductance of the capacitor, at the same time, the first conductor connecting the capacitor and the current carrying conductor and the second conductor connecting the capacitor and the ground end have an annular plane, which can be equivalent to an infinite number of radial conductors, and the magnetic field generated by each conductor can cancel, The parasitic inductance generated by the connecting conductor is substantially zero, and the combination of the two can improve the filtering performance;

2) The structure composed of the capacitor and the connecting conductor of the invention can effectively shield the interference between the input and the output of the filter, and further improve the filtering performance;

3) The invention has a simple structure and a small number of component components, and can effectively reduce the cost and the volume of the filter, and is particularly suitable for an application environment with small installation space and high reliability requirements.

DRAWINGS

1 is a schematic diagram of a conventional conventional capacitor filter;

2 is a schematic diagram of an electromagnetic compatibility filter of the present invention;

3 is a schematic structural view of an electromagnetic compatibility filter of the present invention.

The reference numerals are as follows:

1 2 is a current-carrying conductor; 2 is a connecting conductor of a current-carrying conductor and a capacitor electrode; 3 is a capacitor electrode; 4 is a capacitor; 5 is a capacitor electrode 2; 6 is a connecting conductor of the capacitor electrode 2 and the ground; 7 is a grounding terminal; 8 is a first conductor; 9 is a second conductor; 10 is a metal connector; and 11 is a PCB board.

Embodiments of the invention

The electromagnetic compatibility filter provided by the present invention, as shown in FIG. 2, comprises a current-carrying conductor 1 and a plurality of capacitors 4, the capacitors 4 are distributed on the outer circumference of the current-carrying conductor 1, and one end of the capacitor 4 passes through the first conductor 8 and the current-carrying current. The conductor 1 is electrically connected, and the other end of the capacitor 4 is electrically connected to the ground terminal 7 of the filter through the second conductor 9.

Here, as shown in FIG. 2, four capacitors are taken as an example, and the capacitor 4 is circumferentially distributed outside the current-carrying conductor 1 around the current-carrying conductor 1. The connection capacitor 4 and the first conductor 8 of the current-carrying conductor 1 have an annular planar shape. At the same time, the second conductor 9 connecting the capacitor 4 and the filter ground 7 also has an annular planar shape. The conductor of the annular plane can be equivalently composed of an infinite number of radial conductors, the magnetic field generated by each radial conductor can be completely canceled, the parasitic inductance is substantially zero, and the parasitic inductance of the capacitor itself is very low, when multiple capacitors are circumferential Arranged outside the current-carrying conductor, the equivalent inductance of all capacitors is equal to the parasitic inductance of a single capacitor divided by the number of capacitors, so the parasitic inductance of the capacitor can also be reduced to a very low level, so the above two points can effectively solve the parasitic inductance The problem that the capacitance impedance is too large at high frequencies cannot effectively turn on high frequency interference.

In addition, the current-carrying conductor 1, the first conductor 8, the capacitor 4, and the second conductor 9 are electrically connected in sequence to form a complete metal plane (including only the gap between the capacitors), and the external connection is effectively connected to the zero potential. Under the space, the space coupling interference between the front and rear conductors of the capacitor will be shielded by the metal plane (the gap between the capacitors is small, which can be very effective in the range of less than 1G), thereby solving the problem that the filter cannot work normally. problem.

In the above configuration, the capacitor 4 is circumferentially distributed around the current-carrying conductor 1, but the present invention is not limited thereto, and the function of the above filter can be realized if the distance between each capacitor 4 and the current-carrying conductor 1 is equal. . In order to accommodate the need for mechanical installation, the distance between the capacitors and the current-carrying conductor 1 can of course be unequal.

3 is a schematic view showing a specific structure of the electromagnetic compatibility filter of the present invention, including a current carrying conductor 1, a capacitor 4, a PCB board 11, and a metal connecting member 10, wherein the current carrying conductor 1 is an L-shaped current carrying copper bus. The current-carrying conductor 1 penetrates the PCB board 11. The first end surface of the PCB board 11 is grounded, and the first conductor 8 connecting the current-carrying conductor 1 and the capacitor 4 and the second conductor 9 connecting the capacitor 4 and the ground end of the filter are It is a conduction circuit in the PCB board 11. In this embodiment, taking eight capacitors 4 as an example, the capacitors 4 are divided into four groups, two in each group, and four groups of capacitors are circumferentially distributed around the current-carrying conductor 1 and arranged on the PCB board 11 Two end faces. The metal connector 10 is mounted on the PCB board 11 and is in electrical contact with the current-carrying conductor 1. Therefore, the current-carrying conductor 1 and the PCB board 11 are connected by the metal connector 10, thereby forming a complete filter circuit for filtering. Features. In the present embodiment, the current-carrying conductor 1 is in the vertical direction, and the PCB board 11 is in the horizontal direction, and the current-carrying conductor 1 transfers current from the current-carrying conductor 1 in the vertical direction to the horizontal direction through the metal connecting member 10. On the PCB board 11, a 90° transition is implemented, and then the capacitor 4 on the PCB board 11 is used for filtering.

Industrial applicability

The invention has simple structure and fewer components, which can effectively reduce the volume and cost of the filter. The original filter needs to adopt multiple filter inductors and multiple filter PCBs, and the invention only needs a first-order filter and an inductor. A capacitor PCB can even eliminate the inductor core and the corresponding core fixture, further reducing the volume of the entire filter, so it has a wide range of applications, especially in applications with small installation space and high reliability requirements.

Claims

An electromagnetic compatibility filter, comprising: a current carrying conductor and a plurality of capacitors, wherein the capacitor is distributed on the outer circumference of the current carrying conductor, one end of the capacitor is electrically connected to the current carrying conductor through the first conductor, and the other end of the capacitor is passed through the second The conductor is electrically connected to the ground of the filter.
The electromagnetic compatibility filter according to claim 1, wherein the distance between each of the capacitors and the current carrying conductor is equal.
The electromagnetic compatibility filter according to claim 2, wherein said capacitance is circumferentially distributed around a current carrying conductor.
The electromagnetic compatibility filter according to claim 1, wherein the first conductor connecting the capacitor and the current carrying conductor has an annular planar shape.
The electromagnetic compatibility filter according to claim 1, wherein the second conductor connecting the capacitor and the ground of the filter has an annular planar shape.
The electromagnetic compatibility filter according to claim 1, wherein the second conductor is a PCB board, and the first end surface of the PCB board is grounded, and the PCB board has a through hole through which the current carrying conductor passes. The capacitor is distributed on the second end surface of the PCB board centered on the current carrying conductor.
The electromagnetic compatibility filter according to claim 6, wherein the current-carrying conductor and the PCB board are electrically connected by a metal connecting member.