Share some knowledge of DC power connector

General power connectors are specifically designed to transfer power from one device to another or from one point to another point in the same device. This type of connector usually has relatively high voltage, current, and temperature ratings. Let’s explain the next common power connector, called DC power connector.

Overview of DC power connector knowledge:

The DC power connector is a type of DC connector that is specifically used to transmit DC power to the device. Compared with other power connectors, they have lower current and voltage ratings. They are mainly used for 12 V DC. They are common low-power electronic devices. These connectors are available in male and female types. Their male pins usually have a cylindrical structure, and their internal and external contacts are separated by insulating materials. Male DC connectors are usually called DC jacks, while female DC connectors are called DC sockets. The DC jack is connected to a wire that flows downward from the DC adapter or battery eliminator. The DC socket is soldered to the circuit board to which the DC socket is to be connected.

DC power connector

DC power connector

DC sockets are usually mounted on the edge of the PCB, so there are no other components to prevent the pins from entering the connector. You can always find the ON/OFF switch and the power indicator LED next to the DC outlet. The DC socket is a simple cylindrical structure, and the two contacts are separated by an insulating structure, but the DC socket is not that simple. Even though DC jacks have only two contacts, most DC jacks have three pins. The outer cylindrical contact is GROUND, and the inner pin is positive.

Although most circuit boards have batteries attached, we can still plug in an external DC adapter to operate the circuit. The three-pin structure of the DC socket is used to separate the GROUND terminal of the battery from the GROND terminal of the DC adapter. The positive terminal of the battery and DC adapter can be connected to PIN 1 of the DC socket. PIN 1 and PIN 2 provide power to the PCB. PIN 3 is where the GROUND of the battery is connected.

What are the sockets on the motherboard of the assembled computer

When we get a motherboard, we must first understand the usefulness of the slots on the motherboard. Only when you know it, can you know it well.

On the motherboard, you can find a rectangular slot on the edge. The interface with 20 or 24 jacks is the power supply interface for the motherboard. If you don’t understand, you can see the picture below. Generally, 24 ports are used on mid-to-high-end motherboards, which we also call 24PIN or 24-pin interface design. Generally, the 20PIN interface design used on low-end motherboards. But whether it is 24PIN or 20PIN, the insertion method is the same. This socket design is a foolproof design. What is the fool-proof design? It can prevent you from inserting the wrong direction, only the correct inserting method can be inserted.

USB jack

USB jack

Because you need to provide a stronger and more stable voltage to the CPU, when you install the CPU, the CPU has a power cord that needs to be connected to the motherboard. The motherboard will have a dedicated power socket for the CPU near the CPU socket, generally There are three types: 4PIN, 6PIN, and 8PIN. The number is the number of holes, just count it yourself. You can see the picture below. This socket is also designed to be foolproof, so you don’t have to be afraid of plugging it wrong.

Most of this serial port is now a hard disk interface. You can easily find it on the motherboard. SATA1 and SATA2 will be written under this serial port. Usually used to connect to the hard disk. On some big-brand motherboards, a protective layer is designed on the outer ring to prevent damage to the pins. You can compare the following two pictures yourself. When we buy a computer, we usually see 4 USB jacks at the back of the host. However, there are more and more USB devices now, which is no longer enough, so we will design 2 USB jacks on the front. This is the front USB jack. The wiring also needs to be connected to the USB slot on the motherboard.

This is very similar to USB. We can find one red and one green round hole on the front panel, which is the audio jack, which is used to connect headphones and microphones.

The latest 48Gbps HDMI connection cable will be available soon

The first batch of HDMI 2.1 48G branded cables was announced at the end of 2018, but they have not been formally certified by the HDMI Forum. One of the reasons is that the HDMI 2.1 certification plan is not yet ready. Now the certification of these products is also coming, marked as Ultra High Speed HDMI (Ultra High Speed HDMI). In addition, TV manufacturers are preparing the first batch of ultra-high-definition TVs using HDMI 2.1.

Since the HDMI 2.1 48G cable and the signal source and receiver are physically different from the existing HDMI 1.4/2.0 cables, product manufacturers must adopt new manufacturing methods, and the HDMI Forum must introduce a new certification program, which includes A compliance test to ensure that it works properly at high data rates and supports all functions.

HDMI connection cable

HDMI connection cable


The HDMI Forum admits that cable manufacturers usually have enough experience to build HDMI 2.1 48G products. However, since the HDMI 2.1 48G certification program has not been completed, it is not recommended that they sell products marked with ultra-high-speed HDMI cables.

HDMI connection cable

HDMI connection cable

The HDMI 2.1 48G cable uses 4 data channels, each of which runs at a speed of 12 Gbps, with a total bandwidth of 48 Gbps, which is higher than the current 18 Gbps, while retaining backward compatibility with existing equipment. The additional bandwidth provided by HDMI 2.1 enables it to support new Ultra HD resolutions and refresh rates, including 4Kp/120Hz, 8Kp/100 or 120Hz, 10Kp/100 or 120Hz, and supports upcoming color spaces such as BT.2020( Rec. 2020), 10/12/16 bit color depth. The HDMI Forum plans to launch its UHS HDMI interconnect certification program in the next few months. In the future, “official” HDMI 48G copper and optical cables will be available

Basic knowledge of D-Sub connector for D-type connector

D-type connectors have been widely used for many years. They were originally developed by Cannon in 1952 and are now part of CanT. The D-type connector has been used as a multi-way connector in many applications, but it is probably the most widely known connector for RS-232 serial links. In fact, D-type connectors have been used for serial links on most computers for many years, and various types of D-type connectors can still be found on most computers today.

The D-type connector was originally called a subminiature connector, and the connector is now commonly referred to as a D subminiature connector. Although these connectors were small when they were first introduced, after so many years of development in the connector industry, many sophisticated connector products have been developed and designed in the world, so D-type connectors are no longer considered to be truly ultra-small Connector.

Fast DB 37 Male Connector PCB Through Hole Straight Machined Pin

D-type connectors usually consist of two and sometimes more parallel connection rows. The connector has a D-format metal shell, which not only provides mechanical strength for the connector, but also provides some limited screening. The metal shell of the plug and the socket contacts to provide screening. In addition, panel mount connectors are usually fixed to the panel using nuts with additional threads that allow the mating connector to be fixed to it to prevent it from loosening.

In addition, the free connector can have a back shell that can provide shielding, and can be connected to a cable screen. Or if it is plastic, they can provide protection and also provide strain relief on the cable. As expected, the pin-containing connector is a male D-type connector, while the socket pin-containing connector is a female connector. The original D-type connector has two rows of pins, and the total number of pins is an odd number, which causes the connector to have one pin in another row, resulting in an e D shape, which also prevents the mating mechanism of the connector The direction is incorrect.

the concept of high-voltage interlock is introduced in the connection design

1.2.2High voltage interlock (HVIL)

In terms of the entire high-voltage interconnection system, in order to ensure the safety of the high-voltage system when it is powered on and off, the concept of high-voltage interlock is introduced in the connection design. The simple description is that when the connector is plugged and turned on, the high-voltage circuit is first contacted and turned on, and then the high-voltage interlock signal circuit is turned on; when disconnected, the high-voltage interlock signal is disconnected first, and then the high-voltage circuit is disconnected. Most connector manufacturers put the high-voltage interlock design inside the connector, and some manufacturers put the high-voltage interlock outside the mating cavity through the auxiliary structure design. It is very important to ensure the stability of the high-voltage interlock circuit. If the high-voltage interlock is not continuous, the possible impact will be very bad. For example, when the car is driving, the signal of the high-voltage interlock circuit is abnormal, causing the whole car to suddenly lose power and fail to operate normally, which may cause a traffic accident.

1.2.3  High-voltage interlocking locking structure

Understand that the real secondary lock does not have a secondary protection function, but more effectively protects it. The real meaning is that after the primary lock, if the primary lock fails or no operation is verified in place, the secondary lock is It is a very important function to ensure that the first lock is protected after the first lock is locked. The most commonly used mechanism in the secondary locking structure combined with the primary lock is the moment arm mechanism. Because the primary locking is related to the insertion and extraction force, a form similar to the moment arm mechanism is required according to the mechanical design concept, so as to achieve both labor saving and The connector can be easily inserted in place.

For the requirements of the force arm, USCAR talks about a lot of ergonomic operability of the force arm. The USCAR also stipulates the force requirements of the related primary and secondary locks in the case of mating and mismatching. In fact, most of us would think that USCAR is the standard for connectors, but I think that the USCAR standard is not only a technical standard, but also guides designers to make the structure reliable in the design process, and how to make the structure and performance reliable under the premise of reliable structure and performance. , Can also provide customers with a better product experience. The picture below is a picture of a more common locking structure product.


1.2.4 High-voltage connector protection level

The protection of the connector is mainly divided into three arrangements:

The first is the board end seal: the board end is the connector socket end using four screws to install mechanically. This is a more commonly used structure, but there are also some special structures

high-voltage cable、high-voltage connectors、HVIL

high-voltage cable、high-voltage connectors、HVIL

The second is the plug-to-head seal: the plug-to-head plug means that the male end contains the female end or the female end contains the male end with rubber parts for protection between the radial and axial directions

high-voltage cable、high-voltage connectors、HVIL

high-voltage cable、high-voltage connectors、HVIL


The third is the wire end seal, the protective seal between the wire end connector and the cable

With the development of the market for high-voltage connectors for electric vehicles, the performance requirements of OEMs for product protection are also constantly improving. In the early stage of industry development, the protection requirements of IPI67 can already satisfy most customers. However, in the later period, as the protection failure of connector products appeared on the market, there were more and more cases of product leakage, insulation failure, and even ablation.

he gradual improvement of protection requirements has become the development trend of electric vehicles. The current IP67 requirements cannot meet the normal use requirements. Of course, this is not absolute, and it depends on the location of the connector on the vehicle. According to the layout of the high-voltage circuit in the whole vehicle, it will be suspended under the chassis of the car. It is a principle that high-voltage must not enter the cabin. Therefore, most high-voltage connectors are located on the chassis close to the ground or close to the wheel hub. When the weather is bad, such as severe weather, heavy rain, or some severe cold weather, the water carried by your tires will actually impact these connectors. If you are familiar with the test, the domestic standard does not have IP6K9K. It is found that if IP67 is used, the impact pressure of the high-pressure water gun is actually not as great as 6k9k. When the car is running at high speed and suddenly wading into the water, the instantaneous water pressure rushing to the connector will be very large, so sometimes it is difficult to meet the actual use requirements of IP67. In response to this, the current domestic standard QC/T1067 and the foreign standard USCAR divide the connector seal into two levels S1 and S2. For the S2 level, it is clearly stipulated that the applicable occasion is the lower position of the chassis, and 6K and 9K are recommended, so if the protection is connected in the future, it must be 6K and 9K. If the connector is not arranged in the above position, the IP67 design can actually meet the requirements of the entire vehicle.


1.2.5 Electromagnetic shielding

Electric vehicles have many electronic devices, and electric current will generate magnetic fields, and the whole vehicle parts must have the ability to resist interference. Especially as electric vehicles are now a carrier, unmanned driving will be developed more on this basis, so this technical issue is very important. For high-voltage systems, shielded connectors and cables are very important, but we have to give priority to system-level layout. This is a prerequisite. If your OBC, the location of your layout, including the system DCDC itself may have some congenital problems, no matter how good the connector is, there will be various signal interference problems, so we must first consider the system type, and then consider the component level. Regarding the shielding effectiveness of the connector, two methods are generally adopted.

In the first way, we have a metal shield on some plastic connectors, and the cable shield will be connected to the shield of the metal shell to form an effective 360° shield. In the second way, most high-voltage and low-current connections will not have a secondary connection, and will be connected to the shielding layer of the cable. This method is also commonly used by existing manufacturers, including some of the more well-known domestic ones. OEMs are also considering this approach. We call it spring contact (English), which is actually a spring connection. The benefits of this structure are also many, because the size and space will be smaller, and its contact points will be more; there are many manufacturers of this structure, mainly represented by companies such as BMW Spring in Switzerland and Basel in the United States. They There are many practical and mature application cases in this area.

In most cases, the connection between the wire and the shielding layer will be crimped in the form of metal inner and outer rings. The shielding layer is placed between the two metal rings, and the shielding layer and the metal ring are deformed by cold pressing. Tightly fix. In addition, we also have a shielding method, which uses a structure similar to a watchband spring to replace the spring connection. This structure is often used in Harsh Environment products and has mature technology; we have done relevant tests and can meet the design requirements . The structure is applied to the shielding of new energy electric vehicles, which can not only meet the performance requirements, but also is a punched part, suitable for mass production and high cost performance.

1.2.6Connector material

The material of the connector insulation is generally PA66, PBT, ABS, PC, etc. The contact material is generally made of brass, phosphor bronze, beryllium copper, etc., but the most commonly used materials abroad are copper-nickel-silicon materials. The connector shell material is generally divided into two kinds of materials: plastic and metal.

1. Lightweight

Due to the demand for lightweight vehicles, especially passenger car manufacturers, under the premise of meeting product performance, they will try their best to choose plastic connectors to control the weight of the vehicle.

2.Product use environment

Because the mechanical strength of metal materials is better than plastic. Therefore, in some harsh environments, metal connectors are more suitable. For example, special vehicles, muck trucks, and electrical connection parts that are not protected during the layout of the entire vehicle. At this time, metal connectors are slightly better than plastic connectors in terms of environmental impact and mechanical strength.

3.Shielding implementation

Regarding the shielded connector, since the shell of the metal connector itself is used for conducting the shielding, it forms a carrier for shielding protection. Under normal circumstances, metal connectors are easier to achieve better shielding effectiveness than plastic connectors, and the appearance structure is more compact.



The development trend of high-voltage connectors

The development trend of high-voltage connectors

1  Policy-oriented role

The formulation of the country’s new energy electric vehicle industry policy should be determined in accordance with China’s national conditions. Regarding the development of a green transportation system, the national plan proposes to accelerate the upgrading of vehicle and ship structure and promote the use of new energy vehicles. By 2020, the production and sales of new energy vehicles will reach about 2 million. Accelerate the use of new energy or clean energy vehicles in new and updated public transportation, sanitation, postal, rental, commuting, and light material distribution vehicles in urban built-up areas, and the use of key areas will reach 80%; key areas of ports, airports, railway freight yards, etc. The addition or replacement of work vehicles mainly uses new energy or clean energy vehicles.

Before the end of 2020, all buses in logistics parks, industrial parks, industrial parks, and large-scale separate cities will be replaced with new energy vehicles. Build centralized charging piles and fast charging piles in logistics distribution centers such as logistics parks, industrial parks, industrial parks, large commercial shopping centers, and agricultural wholesale markets. According to the country’s policy orientation, automakers also adjust their internal models in accordance with relevant policies, which determines the development direction of the connector.


2 Platformization and customization

There are also many types of electric vehicles, such as passenger cars, logistics vehicles, including custom connectors. The requirements will be different, or some special requirements will be put forward, so they include unmanned driving, Internet of Things vehicles, New energy, etc., our connector manufacturers should consider, this kind of customization of electric vehicle industry needs (vehicle end and battery end), I think it may be a good choice, we are now moving towards first step. Because in general, these types of cars will be used in different occasions. In fact, they are all subdivisions. Although the volume is not that large, the market belongs to us. We are top-notch in this market. This is also a Good choice.

The second is platformization. In the future, batteries and vehicles will become platform-based. How to maintain in-depth technical communication with customers and form a platform-based product for both parties is very important. There are more domestic OEMs, and everyone’s platforms are different now, such as batteries. There are a lot of whole package factories, and each has its own module solution and battery box group solution. As a connector manufacturer, you need to think about how to make platform-oriented applications.


3 Miniaturization and lightweight

Under the background of the auto industry’s increasing pursuit of energy saving and environmental protection, the lightweight and miniaturization of automobiles has become a technological trend, and it is also the focus of auto manufacturers’ technical competition. By controlling the weight of the entire vehicle, it can effectively reduce fuel consumption, reduce exhaust emissions, and increase fuel consumption. efficiency. In a big environment like the automobile industry, the new energy connector must also be miniaturized and lightweight.

A series of important solutions for the miniaturization and lightweight of automobiles, including the introduction of smaller-sized high-performance copper alloy wires as signal transmission lines, and the introduction of terminals and contact systems that are developing towards miniaturization, as well as the crimping produced by this miniaturization Unstable optimization and reliable verification methods; the principle of using high-performance terminals to reduce the size of low-power transmission wires, and the use of aluminum wires instead of large-diameter copper wires that transmit higher power.

Application parameters of high-voltage connectors in automobiles

Application parameters of high-voltage connectors in automobiles

(1) Use position: As the name suggests, it is the application position of the connector on different high-voltage electrical appliances in the vehicle. Choose the connector.

(2) Rated voltage: the maximum voltage at which electrical equipment (including electricity and power supply equipment) can work stably for a long time.

The rated voltage is proportional to the creepage distance & electric clearance. In other words, the higher the rated voltage requirement, the larger or longer the connector. The design standard of creepage distance & electric clearance is in accordance with GBT 16935.1 (IEC 60664-1)

(3) Rated current: The rated current of electrical equipment refers to the maximum current that is allowed to pass for a long time when the heat does not exceed the long-term allowable temperature of heat under the rated voltage working condition under the reference ambient temperature.

For electric vehicles, P=UI, and the rated current is determined by the power P of the electrical equipment and the output voltage U.

Peak current: The maximum current value generated by an electric vehicle at the moment of rapid acceleration, climbing, or overload.

The current-carrying cross-sectional area is proportional to the rated current of the connector. In other words, the larger the pin/hole/wire cross-section, the larger the current it can pass, and the larger the connector.

(4.1)Design HVIL function purpose

Confirm the integrity of the entire high-voltage system. When the circuit of the high-voltage system is disconnected or the integrity is damaged, the safety measures of the whole vehicle will be activated.

(4.2)Realization of HVIL function

a. The entire system needs to be structured, which must be designed during system development;

b. Mainly through the connector to complete;

c. The HVIL circuit is a low-voltage circuit, which is independent of the power circuit.

(4.3)The realization principle of connector HVIL function

The power and signal terminals should meet:

——When connecting, the power terminal is connected first, and the signal terminal is connected later.

——When disconnected, the signal terminal is disconnected first, and the power terminal is disconnected later.

Special note: the connection of the power terminal indicates a good contact, and a virtual contact is unacceptable

(5) shield

Alternating electric field shielding: In order to reduce the coupling interference voltage of the alternating electric field to the sensitive circuit, a metal shield with good conductivity can be set between the interference source and the sensitive circuit, and the metal shield can be grounded. The main difference between shielded and unshielded connectors is whether a metal shield with good conductivity is provided.

(6) Protection level

The IP protection level is composed of two numbers. The first marked number indicates the level of protection against dust and foreign objects. The second marked number indicates the degree of airtightness of the appliance against moisture and water intrusion. The larger the number, the protection. The higher the level.

(7)Way out

Mainly refers to the angle between the outlet angle of the cable at the end of the electrical connector plug and the normal direction of the socket installation surface. According to this division, there are common 90° (curved) and 180° (straight) outlet electrical connectors.

(8) Socket installation method

In order to meet the needs of OEM designers for different arrangements of connectors


Precautions for the installation of high-voltage connector sockets

Precautions for the installation of high-voltage connector sockets

(1)The voltage selection needs to be matched: the rated voltage of the whole vehicle after load calculation should be less than or equal to the rated voltage of the connector. If the working voltage of the whole vehicle exceeds the rated voltage of the connector for a long time, the electrical connector has the risk of creeping and ablation.

(2)Current selection needs to be matched: the rated current of the whole vehicle after load calculation should be less than or equal to the rated current of the connector. If the working current of the whole vehicle exceeds the rated current of the connector for a long time, the electrical connector may be overloaded and ablated.

(3) Cable selection needs to be matched: the vehicle cable selection and matching are divided into cable current-carrying matching and cable and connector sealing matching. Regarding cable current-carrying, each main engine factory has specialized electrical engineers to carry out matching design, which will not be explained here. .

Seal matching: The connector and cable seal rely on the elastic compression of the rubber seal to provide the contact pressure between the two, thereby achieving reliable protection performance, such as IP67; according to calculations, the realization of a specific contact pressure depends on the specific compression of the seal, and accordingly Introduced, if reliable protection is required, the sealing protection of the connector has specific size requirements for the cable at the beginning of the design;

The current-carrying section of the same specification, the cable can have different outer diameters, such as shielded cable and unshielded cable, national standard cable and LV216 standard cable, which cable is specifically matched, the connector selection specification has a clear statement, so connect Particular attention should be paid to the specification requirements of the adapter cable when selecting the type of the connector to prevent failure of the connector seal.

(4) The whole vehicle needs flexible wiring: For the wiring of the whole vehicle, each OEM has requirements for bending radius and slack; according to the use case of the connector in the whole vehicle, it is recommended that the connector terminal itself is not stressed after the wiring harness is assembled. Only when the wiring harness as a whole is subjected to vibration or impact due to the vehicle’s operation, the strain relief is achieved through the flexibility of the wiring harness. Even if a little strain is transmitted to the connector terminals, the stress generated does not exceed the design holding force of the terminal in the connector.

 Analysis of key items in the design of high-voltage connectors

Temperature rise is one of the most important design key items in connector design. Abnormal temperature rise will cause ablation of the connector due to excessive temperature rise.

The temperature rise of the connector is affected by the following factors:

1. Contact resistance: used for conductive connection, the resistance between two contact carriers, such as pinhole-to-plug contact resistance, pinhole tail and wire crimp resistance, threaded connection copper plate and copper plate contact resistance

2. Material environment heating: When the connector is in a high temperature environment for a long time, because the materials used in the connector are engineering plastics, metal, rubber, etc., especially engineering plastics require a maximum operating temperature of 140 ℃, but when the product is used in an environment that is too high , When the connector heats up due to its own contact with internal resistance when it reaches thermal equilibrium, plus the ambient temperature is higher than the maximum working temperature allowed by the material. At this time, if the connector is in this environment for a long time and the internal temperature cannot be discharged due to the heating of the internal pinholes of the connector, the internal temperature will continue to rise, and the connector will generate a lot of heat, causing the connector to ablate It causes the vehicle to burn, which is a very serious problem. Both rubber materials and metal materials have maximum operating temperature limits, and both need to be considered during design.

3. The connection of the plate end: when bolts are used in the design, or preventive measures should be taken to prevent loosening during the supply; at the same time, when the bolt is connected, the torsion test must be carried out according to the operating specifications. In the case of screw connection of conductive parts, one of the main failure modes is that the tightening torque is not controlled in accordance with the torque requirements, resulting in abnormal temperature rise and ablation of the connection part.

4. Derating curve: Now let’s discuss the derating curve. In my understanding, the derating curve is like choosing a product. This product should be used in a specific environment. At this time, when choosing a product, According to an attribute value of this product, determine which range of products you choose. The derating curve diagram of the high-voltage connector is to provide customers with a menu, and customers choose their own suitable dishes according to their tastes according to this menu.

The derating curve is the different values corresponding to different currents under different working environment temperatures. These values are a graph obtained by the dot method. With this derating curve graph, the use conditions of the connector can be seen more intuitively.


The figure below is an illustration of the temperature rise and derating curv

Temperature rise and derating curve value


Temperature rise graph


Derating curve



Application of high voltage connector in vehicle system

Connectors for new energy vehicles are one of the major categories of connectors. In recent years, with the development of new energy vehicles in the country, they are gradually separated from traditional high-voltage and high-current and traditional low-voltage automotive connectors.

Compared with traditional high-voltage and high-current connectors, the working conditions of new energy vehicle connectors are more complicated and changeable, and the reliability requirements of the connectors are higher; compared with traditional low-voltage automotive connectors, due to the increase in voltage level ( The current mainstream system voltage is higher than 300V DC), which increases the risk of human body injury from electric shock, and has higher requirements on the safety of the connector; therefore, the insulation and protection requirements of the product are improved compared with traditional low-voltage plug-ins.

The role of the connector for new energy vehicles is mainly to ensure the high-voltage interconnection system of the vehicle, that is, to build a bridge where the internal circuit is blocked or isolated to allow current to flow. The composition of the connector for new energy vehicles can generally be divided into three parts: auxiliary structures such as housing and sealing parts, insulating parts, and conductive contact pairs. Through the mating and mutual cooperation between the plug sheath and the socket sheath, the function of connection and conduction can be achieved.

The high-voltage connector is mainly used in the high-voltage and high-current circuit of new energy vehicles. It acts simultaneously with the conductive cable. It transmits the energy of the battery pack to various parts of the vehicle system through different electrical circuits, such as battery packs, motor controllers, and DCDC. Body power units such as converters and chargers.

The following figure is a layout diagram of the high-voltage connector in the application of the whole vehicle system.