WO2021243613A1

WO2021243613A1 - Emi filter, motor drive system and electric oil pump

Info

Publication number: WO2021243613A1
Application number: PCT/CN2020/094230
Authority: WO
Inventors: Youqing Xiang; Geng LIU; Xiaoyuan Hong; Wufeng Qiu; Nan ZHENG; Jianfeng Yin
Original assignee: Johnson Electric (Guangdong) Co., Ltd.
Priority date: 2020-06-03
Filing date: 2020-06-03
Publication date: 2021-12-09

Abstract

An electromagnetic interference (EMI) filter, includes: a first input terminal and a second input terminal configured to be coupled to an external power source; a first output terminal and a second output terminal, wherein a first conductive path is defined between the first input terminal and the first output terminal, and a second conductive path is defined between the second input terminal and the second output terminal; a first X-capacitor unit, a common mode choke and a Y-capacitor unit connected between the first conductive path and the second conductive path; and a differential mode choke connected in the first conductive path; wherein the first X-capacitor unit and the common mode choke are electrically closer to the first and second input terminals than the differential mode choke.

Description

EMI FILTER, MOTOR DRIVE SYSTEM AND ELECTRIC OIL PUMP

Technical Field

The present disclosure relates to the field of filtering, and particularly relates to an Electromagnetic Interference (EMI) filter, a motor drive system and an electric oil pump.

Background Art

Original Equipment Manufacturer (OEM) and various international organizations in the automotive field are promoting increasingly strict standards to reduce EMI noise in electronic devices. As the demand for smaller and more compact motors increases, the design, size and cost of traditional EMI filter of electric oil pumps cannot meet increasingly strict standards.

Technical Problem

In view of this, the embodiments of the present disclosure provide an EMI filter, a motor drive system, and an electric oil pump to solve the problem that the traditional EMI filter cannot meet increasingly strict standards.

Technical Solution

According to one aspect, an EMI filter, includes:

a first input terminal and a second input terminal configured to be coupled to an external power source,

a first output terminal and a second output terminal, wherein a first conductive path is defined between the first input terminal and the first output terminal, and a second conductive path is defined between the second input terminal and the second output terminal,

a first X-capacitor unit, a common mode choke and a first Y-capacitor unit connected between the first conductive path and the second conductive path, and

a differential mode choke connected in the first conductive path,

wherein the first X-capacitor unit and the common mode choke are electrically closer to the first and second input terminals than the differential mode choke.

Preferably, the common mode choke comprises a first winding coil and a second winding coil, the first winding coil comprises a first lead-out electrode and a second lead-out electrode, the second winding coil comprises a third lead-out electrode and a fourth lead-out electrode, the second and fourth lead-out electrodes are installed in a first PCB, the differential mode choke is disposed on the first PCB and connected to the second lead-out electrode through trace on the first PCB.

Preferably, the first lead-out electrode and the third lead-out electrode are fixedly installed in a second PCB, and the first X capacitor unit is disposed on the second PCB and connected to the first lead-out electrode and the third lead-out electrode through trace on the second PCB.

Preferably, the first X capacitor unit is welded between the first lead-out electrode and the third lead-out electrode.

Preferably, the EMI filter further comprises a reverse polarity protection switch connected in the first conductive path, the first output terminal is connected to the differential mode choke through the reverse polarity protection switch, or the reverse polarity protection switch is connected to the first output terminal through the differential mode choke.

Preferably, a second X capacitor unit and a second Y capacitor unit are connected to a first terminal of the reverse polarity protection switch close to the first input terminal, a third X capacitor unit and a third Y capacitor unit are connected to a second terminal of the reverse polarity protection switch, the second X capacitor unit and the third X capacitor unit are coupled between the first conductive path and the second conductive path, the second Y capacitor unit and the third Y capacitor unit each includes a first subunit and a second subunit, wherein the first subunit or second subunit comprises one or more capacitors, the first subunit is connected between the first conductive path and ground, and the second subunit is connected between the second conductive path and ground.

Preferably, the EMI filter further comprises a fourth X capacitor unit connected to the first output terminal and coupled between the first conductive path and the second conductive path.

Preferably, the EMI filter further comprises a large-capacity capacitor and / or a fifth X capacitor unit, the large-capacity capacitor and the fifth X capacitor unit are coupled between the first output terminal and the second output terminal.

According to another aspect, a motor drive system, includes an inverter circuit and the above described EMI filter, a DC power is filtered by the EMI filter, and an AC drive signal for driving motor is generated by the inverter circuit.

According to another aspect, an electric oil pump includes the above described EMI filter or the above described motor drive system.

Advantageous Effects

In the embodiments of the present disclosure, the common mode choke and the first X capacitor unit are arranged closer to the power supply than the differential mode choke, so that common mode noise can be better filtered; and the common mode chock and the first X capacitor are closer to the power supply, such that it is easier to lay out positive and negative traces on the first PCB to avoid noise crosstalk caused by unstable stray capacitance and further reduce the noise.

Description of Drawings

In order to more clearly explain the technical solutions in the embodiments of the present disclosure, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only introduce some embodiments, for those of ordinary skill in the art, without paying creative labor, other drawings may be obtained based on these drawings.

FIG. 1 is a schematic diagram of a circuit of a motor driving system according to an embodiment of the present disclosure;

FIG. 2 is a schematic diagram of a circuit of a motor drive system according to another embodiment of the present disclosure;

FIG. 3 is a schematic structural diagram of a motor drive system according to an embodiment of the present disclosure;

FIG. 4 is a schematic structural diagram of a common mode choke according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram showing noise performance corresponding to the motor drive system of the present disclosure;

FIG. 6 is a schematic diagram of an oil pump according to an embodiment of the present disclosure.

Mode for Invention

The subject matter will be described in conjunction with the accompanying drawings and the preferred embodiments. The described embodiments are only a few and not all of the embodiments of the present disclosure. All other embodiments obtained by those ordinarily skilled in the art based on the embodiments of the present disclosure without any creative efforts fall within the protection scope of the present disclosure. It is to be understood that, the drawings are provided for reference only and are not intended to be limiting of the invention. The dimensions shown in the drawings are only for convenience of illustration and are not intended to be limiting.

In order to explain the technical solutions described in the present disclosure, the following will be described with specific embodiments.

FIG. 1 is a schematic diagram of a circuit of a motor driving system including an EMI filter according to an embodiment of the present disclosure. As shown in FIG. 1, the EMI filter includes:

a first input terminal 310 and a second input terminal 311 for coupling to an external power source, such as a battery;

a first output terminal 320 and a second output terminal 321, wherein the first output terminal 320 and the first input terminal 310 are connected through a first conductive path 330, and the second output terminal 321 and the second input terminal 311 are connected through a second conductive path 331;

a first X capacitor unit 340 and a common mode choke 350 coupled between the first conductive path 330 and the second conductive path 331, and a plurality of Y capacitor units respectively arranged between the first conductive path 330 and ground, the second conductive path 331 and ground;

a differential mode choke 370 provided on the first conductive path 330;

wherein the first X capacitor unit 340 and the common mode choke 350 are closer to the first input terminal 310 and the second input terminal 311 than the differential mode choke 370. Preferably, the first X capacitor unit 340 and the common mode choke 350 are closer to the first input terminal 310 and the second input terminal 311 than the differential mode choke 370 in the resistance path.

Specifically, the common mode choke 350 includes a first winding coil 351 and a second winding coil 352, the first winding coil 351 includes a first lead-out electrode 3511 and a second lead-out electrode 3512, and the second winding coil 352 includes a third lead-out electrode 3521 and the fourth lead-out electrode 3522. The first lead-out electrode 3511 is connected to the first input terminal 310, the third lead-out electrode 3521 is connected to the second input terminal 311, the second lead-out electrode 3512 is connected to the first output terminal 320 through the differential mode choke 370, and the fourth lead-out electrode 3522 is connected to the second output terminal 321. According to the above circuit connection, the first X capacitor unit 340 may also be closer to the first input terminal 310 and the second input terminal 311 than the common mode choke 350.

The X capacitor unit in the present disclosure includes the first X capacitor unit 340, a second X capacitor unit 341, a third X capacitor unit 342, and a fourth X capacitor unit 343. Each X capacitor unit may include one or more capacitors. The X capacitor unit refers to a capacitor unit connected across the input line to eliminate the differential mode interference. The Y capacitor unit in the present disclosure includes the first Y capacitor unit 360, a second Y capacitor unit 361 and a third Y capacitor unit 362, which is connected between the input line and the ground, and is configured to eliminate common mode interference. The Y capacitor unit may include a first subunit Y1 and a second subunit Y2, and the first subunit Y1 or second subunit Y2 may include one or more capacitors.

The first X capacitor unit 340 is coupled between the first input terminal 310 and the second input terminal 311. The first subunit Y1 of the first Y capacitor unit 360 is connected between the first conductive path 330 and ground, and the second subunit Y2 of the first Y capacitor unit 360 is connected between the second conductive path 331 and ground.

The power supply connected to the first input terminal 310 and the second input terminal 311 may be a DC power supply. For example, the power supply may be a battery, including a rechargeable battery or a non-rechargeable battery. When the power supply is a DC power supply, after the noise is filtered by the EMI filter, it can be converted into AC power by the inverter 2, and then the motor 4 is driven to rotate by the AC power.

When the first input terminal 310 and the second input terminal 311 are coupled to a DC power source, the first input terminal 310 may be coupled to a positive electrode, and the second input terminal 311 may be coupled to a negative electrode. By providing a differential mode choke 370 on the first conductive path 330, the differential mode interference existing in the current output from the positive electrode of the power source can be effectively filtered.

The first X capacitor unit 340 is coupled between the first conductive path 330 and the second conductive path 331, and includes at least one capacitor, for example, the first X capacitor unit 340 is a single capacitor, the two pins of the single capacitor are connected to the first conductive path 330 and the second conductive path 331, respectively. When the first X capacitor unit 340 includes two or more capacitors connected in series, the first end of the capacitors connected in series is connected to the first conductive path 330, and the second end of the capacitors connected in series is connected to the second conductive path 331.

In an embodiment of the present disclosure, as shown in FIG. 1, the EMI filter may further include a reverse polarity protection switch 380, the reverse polarity protection switch 380 is connected in the first conductive path 330, and the reverse protection switch 380 is closer to the first output terminal 320 than the differential mode choke 370. That is, the first output terminal 320 is connected to the differential mode choke coil 370 through the reverse polarity protection switch 380.

In another embodiment, as shown in FIG. 2, the reverse polarity protection switch 380 is connected in the first conductive path 330, and the differential mode choke coil 370 is closer to the first output terminal 320 than the reverse polarity protection switch 380. That is, the reverse polarity protection switch 380 is connected to the first output terminal 320 through the differential mode choke 370.

The reverse polarity protection switch 380 may be a reverse polarity protection MOSFET.

In embodiments, as shown in FIG. 1 or FIG. 2, the second X capacitor unit 341 and the second Y capacitor unit 361 are connected to a first terminal of the reverse polarity protection switch 380 connected to the common mode choke 350. The third X capacitor unit 342 and the third Y capacitor unit 362 are connected to a second terminal of the reverse polarity protection switch 380. The second X capacitor unit 341 and the third X capacitor unit 342 are coupled between the first conductive path 330 and the second conductive path 331. The second Y capacitor unit 361 and the third Y capacitor unit 362 respectively include the first subunit Y1 and a second subunit Y2, wherein the first subunit Y1 or the second subunit Y2 may include one or more capacitors. For example, the first subunit Y1 includes two capacitors connected in series, the second subunit Y2 includes a capacitor, and the first subunit Y1 is connected between the first conductive path 330 and ground, and the second subunit Y2 is connected between the second conductive path 331 and ground. The ground point of the first subunit Y1 and the second subunit Y2 are connected together.

In one embodiment, as shown in FIG. 1, the fourth X capacitor unit 343 is connected to the connection node between the differential mode choke 370 and the common mode choke 350. The fourth X capacitor unit 343 is coupled between the first conductive path 330 and the second conductive path 331 at the second lead-out electrode 3512 or a terminal of the differential mode choke 370.

In other embodiment, as shown in FIG. 2, the fourth X capacitor unit 343 is connected to the first output terminal 320 and also be coupled between the first conductive path 330 and the second conductive path 331.

Preferably, as shown in FIG. 1 and FIG. 2, the EMI filter further includes a large-capacity capacitor 390 and/or a fifth X capacitor unit 344, the large-capacity capacitor 390 and the fifth X capacitor unit 344 are coupled between the first output terminal 320 and the second output terminal 321.

As electronic products such as motor and oil pump have become more compact, the installation space of the motor drive system including the EMI filter is limited, and the requirements for EMI are becoming more and more strict. The present disclosure further improves the installation structure of electronic components of the EMI filter.

As shown in FIG. 3, the EMI filter includes a first printed circuit board (PCB) 200. The electronic components including the common mode choke 370, the Y capacitor units, the second X capacitor unit 341, the third X capacitor unit 342, the fourth X capacitor unit 343, the fifth X capacitor unit 344, and the reverse polarity protection switch 380 are all mounted on the first PCB 200, the first X capacitor unit 340 is not mounted on the first PCB 200. The common mode choke 350 is installed on the first PCB 200, the common mode choke 350 further includes a ring-shaped magnetic core 11, and the first winding coil 351 and the second winding coil 352 are wound around the ring-shaped magnetic core 11, the first lead-out electrode 3511 and the third lead-out electrode 3521 act as the first input terminal 310 and the second input terminal 311 of the EMI filter, and the second lead-out electrode 3512 and the fourth lead-out electrode 3522 are fixedly mounted on the first PCB 200. The EMI filter further includes a second PCB 300. The second PCB 300 is provided with a through hole for the first lead-out electrode 3511 and the third lead-out electrode 3521 to pass through, and the second PCB 300 is fixed on the common mode choke 350. The first X capacitor unit 340 is mounted on the second PCB 300, and is connected to the through hole through the traces layout on the second PCB 300, and is electrically connected to the first lead-out electrode 3511 and the third lead-out electrode 3521.

The common mode choke 350 is mounted on the first PCB 200, the first lead-out electrode 3511, the third lead-out electrode 3521 of the common mode choke 350 act as the first input terminal 310 and the third input terminal 311, the first X capacitor unit 340 is connected to the common mode choke 350 through the trace on the second PCB 300, and the first X capacitor unit 340 and the common mode choke 350 are closer to the power supply than the differential mode choke 370 on the first PCB, such that a better filtering effect for common mode noise can be achieved and the size of the first PCB 200 is reduced. Further, it is easier to balance the layout of the positive and negative traces on the first PCB 200, to avoid common noise crosstalk caused by unbalanced stray capacitance, and obtain a better EMC performance. Especially in high power density applications, the EMI filter can be used in most motor control applications and meet the EMI requirement promoted by OEM and various international organizations in the automotive field.

Those skilled in the art can understand that the connections between the first capacitor unit 340 and the first lead-out electrode 3511 and the third lead-out electrode 3521 can also be in other ways, such as soldering the pins of the capacitor directly to the first lead-out electrode 3511 and the third lead-out electrode 3521 without using the second PCB 300.

The common mode choke 350 may be a conventional common mode choke, or a common mode choke as shown in FIG. 3 and FIG.4, the common mode choke 350 includes the ring-shaped magnetic core 11 and two winding coils 351 and 352 wound around the ring-shaped magnetic core 11, the magnetic core 11 has a through hole 14 in the center; wherein each winding coil 351 and 352 includes at least two connecting segments 21 and 22 connected in sequence around the magnetic core 11, each connecting segment 21 and 22 is a flat conductor, and a flat surface of each connecting segment 21 and 22 surrounds the surfaces 102, 12, 13 of the magnetic core 11. The at least two connecting segments 21 and 22 has a u-shaped configuration, which includes a base arm and two arms extending vertically from both ends of the base arm. The base arm of the u-shaped connecting segment is attached to the axial end face of the magnetic core, and both arms are attached to the inner and outer sides of the magnetic core respectively.

FIG. 5 is a schematic diagram showing the noise performance curve of the EMI filter according to the embodiment of the present disclosure. Curve L1 and L2 denote the EMI standards (the maximum limit) that the peak value and average value of the noise need to meet, and curves L3 and L4 are actual signal curves of the embodiment of the present disclosure. It can be seen from FIG. 5 that the signal obtained after the filtering process of the EMI filter according to the embodiment of the present disclosure can meet EMI requirements.

In addition, an embodiment of the present disclosure also provides a motor drive system. As shown in FIGs. 1 and 2, the motor drive system includes the inverter circuit 2 and the EMI filter. The power provided by the DC power source is filtered by the EMI filter, then an AC drive signal for driving the motor 4 is converted by the inverter circuit 2, the inverter circuit 2 is disposed on the first PCB 200.

As shown in FIG. 6, the present disclosure also provides an electric oil pump. The electric oil pump includes the motor 4, a motor drive system 3, and a pump body. In the automobile, the installation space of the oil pump is limited, and the space of each module in the oil pump is strictly limited. Using the motor drive system of the present disclosure can save space and make it easier to balance positive and negative wiring layout of the first PCB 200 to avoid common noise crosstalk caused by stray capacitance imbalance, and can achieve better EMC performance, can meet the EMI noise standards of OEM and various international organizations in the automotive field.

The above-mentioned embodiments are only used to illustrate the technical solutions of the present disclosure, not to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that the technical solutions described in the foregoing embodiments can also be modified, or some of the technical features can be equivalently replaced; and these modifications or replacements that do not depart from the spirit and scope of the technical solutions of the embodiments of the present disclosure should be included in the protection scope of this application.

Claims

An electromagnetic interference (EMI) filter, comprising:

a first input terminal (310) and a second input terminal (311) configured to be coupled to an external power source,

a first output terminal (320）and a second output terminal (321), wherein a first conductive path (330) is defined between the first input terminal (310) and the first output terminal (320), and a second conductive path (331) is defined between the second input terminal (311) and the second output terminal (321),

a first X-capacitor unit (340), a common mode choke (350) and a first Y-capacitor unit connected between the first conductive path (330) and the second conductive path (331), and

a differential mode choke (370) connected in the first conductive path (330),

wherein the first X-capacitor unit (340) and the common mode choke (350) are electrically closer to the first and second input terminals (310, 311) than the differential mode choke (370).
The EMI filter as claimed in claim 1, wherein the common mode choke (350) comprises a first winding coil (351) and a second winding coil (352), the first winding coil (351) comprises a first lead-out electrode (3511) and a second lead-out electrode (3512), the second winding coil (352) comprises a third lead-out electrode (3521) and a fourth lead-out electrode (3522), the second and fourth lead-out electrodes (3512, 3522) are installed in a first PCB (200), the differential mode choke (370) is disposed on the first PCB (200) and connected to the second lead-out electrode (3512) through trace on the first PCB (200).
The EMI filter as claimed in claim 1, wherein the first lead-out electrode (3511) and the third lead-out electrode (3521) are fixedly installed in a second PCB (300), and the first X capacitor unit (340) is disposed on the second PCB (300) and connected to the first lead-out electrode (3511) and the third lead-out electrode (3521) through trace on the second PCB (300).
The EMI filter as claimed in claim 2, wherein the first X capacitor unit (340) is welded between the first lead-out electrode (3511) and the third lead-out electrode (3521).
The EMI filter as claimed in claim 1, wherein the EMI filter further comprises a reverse polarity protection switch (380) connected in the first conductive path (330), the first output terminal (320) is connected to the differential mode choke (370) through the reverse polarity protection switch (380), or the reverse polarity protection switch (380) is connected to the first output terminal (320) through the differential mode choke (370).
The EMI filter as claimed in claim 5, wherein a second X capacitor unit (341) and a second Y capacitor unit (361) are connected to a first terminal of the reverse polarity protection switch (380) close to the first input terminal (310), a third X capacitor unit (342) and a third Y capacitor unit (362) are connected to a second terminal of the reverse polarity protection switch (380), the second X capacitor unit (341) and the third X capacitor unit (342) are coupled between the first conductive path (330) and the second conductive path (331), the second Y capacitor unit (361) and the third Y capacitor unit (362) each includes a first subunit (Y1) and a second subunit (Y2), wherein the first subunit (Y1) or second subunit (Y2) comprises one or more capacitors, the first subunit (Y1) is connected between the first conductive path (330) and ground, and the second subunit (Y2) is connected between the second conductive path (331) and ground.
The EMI filter as claimed in claim 6, wherein the EMI filter further comprises a fourth X capacitor unit (343) connected to the first output terminal (320) and coupled between the first conductive path (330) and the second conductive path (331).
The EMI filter as claimed in claim 1, wherein the EMI filter further comprises a large-capacity capacitor (390) and / or a fifth X capacitor unit (344), the large-capacity capacitor (390) and the fifth X capacitor unit (344) are coupled between the first output terminal (320) and the second output terminal (321).
A motor drive system, wherein the motor drive system comprises an inverter circuit, and the EMI filter according to any one of claims 1-8, a DC power is filtered by the EMI filter, and an AC drive signal for driving motor is generated by the inverter circuit.
An electric oil pump, wherein the electric oil pump comprises the EMI filter according to any one of claims 1-8 or the motor drive system according to claim 9.