At present, the new energy vehicle industry is in the stage of exploration and a small amount of trial production, and there is no industrial scale at home or abroad, so the related parts are also in the trial production stage. However, compared with the overall technical level of automotive wiring harnesses, which is mainly based on wiring harness assembly in China, the technical foundation of foreign automotive wiring harnesses is solid, and there are solutions for high-voltage wiring harnesses. For example, Amphenol, the first industry leader to enter the field of electric and hybrid vehicle charging connectors, developed a high-voltage wiring harness for electric vehicles with simple structure, excellent performance, and high user acceptance. Reliable work under high temperature, vibration, limited space and other harsh environments has been widely used by various domestic and foreign automobile manufacturers; TYCO, Delphi (Delphi), LS and other foreign companies followed closely and launched their own High voltage wiring harness solutions and related products.
Entering the text, in order to make up for the research gap in the field of high-voltage wiring harnesses for electric passenger vehicles in my country, and to get rid of the current situation that the high-voltage wiring harnesses required in electric passenger vehicles in China are basically directly purchased from foreign products, a high-voltage high-current electric passenger vehicle high-voltage wiring is developed. Independent research and development of beams. According to the use requirements of the high-voltage electrical system of the electric passenger vehicle for the high-voltage wiring harness, the designed high-voltage wiring harness for the electric passenger vehicle should meet the following requirements: a. The usability requirements of high voltage and high current. b. Safety and reliability requirements such as anti-electromagnetic interference, waterproof, anti-vibration, wear-resistant, flame-retardant and reliable contact.
1. Design of high-voltage cables
The traditional wire harness processing manufacturer's car is powered by a gasoline engine. The traditional car cable is used to transmit control signals, and the current and voltage it withstands are very small, so the cable diameter is small, and the structure is only a conductor plus insulation, which is very simple. However, according to the use requirements of high-voltage cables for electric passenger vehicles, the high-voltage cables for electric passenger vehicles mainly play the role of transmitting energy, and the energy of the battery needs to be transmitted to various subsystems. current transmission. The high-voltage cables of electric passenger vehicles are subject to higher voltage (up to 600 V rated voltage), larger current (up to 600 A rated current), and stronger electromagnetic radiation, so the diameter of the cable increases significantly. The equipment produces strong electromagnetic interference, which affects the normal operation of other electronic equipment. The cable is also designed with an anti-electromagnetic interference shielding structure, that is, a coaxial structure is used, and the inner conductor and the outer conductor (shielding) are used together. The magnetic field in the cable is distributed in concentric circles. The electric field points from the inner conductor and ends at the outer conductor, so that the external electromagnetic field around the cable is zero, that is, the electromagnetic radiation is shielded, thereby ensuring the normal operation of the electric vehicle.
Environmental protection wire has the following major characteristics: 1. High flame retardancy, environmental protection wire can ensure its high requirements for fire protection buildings. In case of fire, environmental protection wire can not only be difficult to burn, but also prevent the spread of flames and disasters after combustion. expansion. 2. Halogen-free, the use of green environmental protection edge layer, sheath and special oxygen barrier material, not only makes the environmental protection wire have good electrical properties, physical and mechanical properties, but also ensures that the product does not contain halogen, and solves the problem of formation of its combustion. "Secondary pollution" avoids the "dioxin" substances that can be produced when traditional PVC wires are burned. 3. Low-element, the edge and sheath of the environmental protection wire do not contain lead, cadmium and other harmful heavy metals, and will not pollute the soil and water sources when the environmental protection wire is used and disposed of. And after harsh sex experiments, the mice were safe and sound under the prescribed experimental conditions. 4. No corrosive gas is produced, and new special coating materials that are non-polluting to the environment are used, so that the environmentally friendly wires will not generate HCL and other gases during production, use and combustion, and emit very little acid gas, which is harmful to personnel, equipment and instruments. The damage is small, showing the characteristics of environmental protection. 5. High light transmittance, the smoke generated when the environmental protection wire is burned is extremely thin, which is conducive to the evacuation of personnel and the fire-fighting work. Generally speaking, the light transmittance of environmentally friendly wire products is greater than 40%, which is much higher than the standard of less than 20% light transmittance of traditional flame retardant wires and cables. 6. High protection against UV light or water.
Insulation materials for automobile cables of early wire harness processing manufacturers are mainly PVC (polyvinyl chloride), but PVC contains lead, which is harmful to the human body. XLPE (cross-linked polyethylene), silicone rubber and other materials are replaced. Since the high-voltage cables for electric passenger vehicles not only meet the requirements of high-voltage and high-current, anti-electromagnetic interference, but also wear-resistant and flame-retardant, the properties of these materials are compared:
a. LSZH can be divided into two categories: PO (polyolefin) and EPR (ethylene propylene rubber), among which PO cable material is the mainstream. There are a lot of AI(OH)3, Mg(OH)2 inorganic flame retardants in the formula of PO type LSZH flame retardant cable material, so that the cable material has better flame retardant, low smoke, halogen free, low toxicity, etc. However, it is also different from other non-flame retardant materials and halogen-containing flame retardant materials in terms of physical and mechanical properties, electrical properties and extrusion process properties.
b. TPE is a polymer material with both rubber and thermoplastic properties. It shows the high elasticity of rubber at room temperature and can be plasticized at high temperature. However, the material is not wear-resistant and cannot meet the high-voltage lines of electric passenger vehicles. bundle usage requirements.
c. XLPE is made of ordinary PE (polyethylene) material with a temperature resistance grade of 75 ℃ after being cross-linked by irradiation. Its temperature resistance grade can reach 150 ℃, and it has excellent physical and mechanical properties, overload resistance and Long life and other characteristics, but not flame retardant.
d. The breakdown voltage of silicone rubber is high, so it has arc resistance, leakage trace resistance and ozone resistance. It also has good high and low temperature resistance, high temperature resistance up to 200 ℃, good insulation performance Stable performance and flame retardant under conditions. After comparing the properties of the above materials, silicone rubber has become the first choice for high-voltage cable insulation materials for electric passenger vehicles due to its good physical and mechanical properties, long service life and low price. The structure of the final designed electric passenger vehicle high-voltage cable is shown in the figure:
2. Design of high voltage connector
2.1 Design of high current contacts
Usually the connector (mainly refers to the contacts) has a temperature limit for use. Once the use temperature exceeds the specified limit, the safety of the connector will be reduced due to heat, or even failure and damage. There are two main reasons for the increase in the temperature of the connector:
a. The car itself. The hottest part of the car is around the engine. For example, the temperature around the traditional car engine can reach more than 125 ℃.
b. The connector itself. The connector wiring harness manufacturer will generate heat during use, and the contacts inserted in the connector have contact resistance. The greater the contact resistance, the greater the power loss, the higher the temperature of the contact, and the lower the reliability. In this regard, special attention should be paid when designing high-voltage and high-current connectors for electric passenger vehicles. In order to avoid excessive use temperature to damage the insulating material in the connector, reduce its insulating performance, or even burn out, and reduce the elasticity of the contact after being heated, or form an insulating film in the contact area, reduce the contact reliability, increase Large contact resistance, and then aggravate the use of temperature, such a vicious circle eventually leads to the failure of the connection and contact, and the high-current contacts in the high-voltage and high-current connectors of electric passenger vehicles must be reasonably designed.
When designing high-current contacts, the choice of contact form will directly determine the quality and cost of the connector. Generally, there are three main contact forms of contact pieces: leaf type, leaf spring type and wire spring type, as shown in Figure .
The socket of the chip contact is slotted and closed in a cylindrical cylinder. The socket is processed with beryllium bronze wire (rod), the raw material price is more expensive, and the subsequent closing process is difficult to control, the consistency of product quality is difficult to guarantee, and the cost is high. .
The socket of the contact part of the leaf spring type wiring harness processing manufacturer is a crown spring hole, and there are 1 to 2 leaf spring coils placed in the socket. It has an elastic spring ring; when the socket and the pin are matched, each spring piece is in contact with the pin and produces a pressing force to ensure stable contact at multiple points; the leaf spring socket is made of brass machine parts and crown springs Composed of stamping parts, the product has good consistency and low cost. Amphenol's patented RADSOK socket structure (shown in Figure 3), which uses hyperbolic crown spring technology, increases the contact area by 65%, and has a silver-plated surface for high wear resistance.
The jack of the wire spring contact is a wire spring hole. The structure of the jack is similar to that of the leaf spring jack, but the wire spring jack is composed of spring wires. Although the wire spring jack has excellent performance, the process is complicated. , the cost is also higher.
After comparing the above-mentioned contact types of contacts, the high-current high-current connector for electric passenger vehicles adopts a high-current leaf spring type contact. At the same time, in order to improve the contact reliability and current-carrying capacity, and to meet other index requirements of the high-current contact piece, the high-current leaf spring contact piece adopts a double-reed two-stage leaf spring socket. Finally, through the calculation of the contact resistance of the high-current contact, the design of the structure and the modification of the sample design, the high-current contact is successfully designed.
2.2 Design of high pressure resistance
In order to meet the design requirements of high-voltage connectors for electric passenger vehicles, it is necessary to ensure that all parts of the high-voltage connector have sufficient dielectric strength through structural design and material selection to ensure its high-voltage resistance performance. The high-voltage performance design of high-voltage connectors for electric passenger vehicles mainly includes creepage distance, interface air gap and insulating materials.
The creepage distance means that when the working voltage is too large, the instantaneous overvoltage will cause the current to release the arc along the gap between the insulation, which will damage the device and even the operator. This insulation gap is the creepage distance, and the continuous working voltage of the arc determines the creepage distance. electrical distance. In the structural design of high-voltage connectors, the creepage distance should be increased as much as possible. Considering that the dielectric withstand voltage of the connector is more than 400V, after careful calculation and checking, the creepage distance of the connector is designed to be more than 24mm, which can fully meet the high voltage Connector 600V requirements for use.
In order to improve the high pressure resistance of the connector, when the connector is inserted, its interface should be fitted with no air gap. The interface of the connector mainly includes the mating interface of the plug connector and the socket connector, the connection parts of the connector contacts and the wires. These parts need to be filled with medium without air to reliably ensure that the connector is not broken down. In order to eliminate the existence of the interface air gap, the following measures have been taken in the design of the high-voltage connector:
a. Soft insulating material is used at the insertion interface to ensure that the air gap is filled while the insertion is in place.
b. The insulation outside the jack contacts is in the form of molding, filling the gaps outside the contacts.
c. The mating surface of the plug and socket adopts a tapered structure.
d. Part of the cable insulation after the contact piece connects the cable extends into the connector housing insulation.
In order to improve the high-voltage resistance performance of the connector of the wire harness processing manufacturer, the high-voltage connector of the electric passenger car is selected with good insulation performance, high breakdown voltage, high dielectric strength, good stability under high temperature and high pressure, arc resistance, resistance to leakage traces, and moisture absorption. Low PPA (polyphthalamide) plastic.
2.3 Overall structure design
Figure 4 shows the structure of the electric passenger car high-voltage connector designed by the final wire harness manufacturer. The structure of the high-voltage connector is, from inside to outside, the inner conductor, the insulating layer, the shielding layer, and the outer shell.
3. Overall design of high voltage wiring harness
3.1 Shielding performance design
In order to make the designed high-voltage wire harness not only meet the basic reliable electrical connection requirements, but also have excellent electromagnetic shielding performance, the shielding performance design of the high-voltage wire harness is developed. The shielding performance design of the high-voltage wiring harness mainly includes the shielding performance design of the high-voltage cable itself, the shielding performance design of the junction of the high-voltage cable and the high-voltage connector, the shielding performance design of the high-voltage connector itself, and the high-voltage connector. In order to improve the shielding performance of the high-voltage cable itself, the high-voltage cable adopts a shielding structure. If the cable is composed of a signal line and a power line, more attention should be paid to this point. In order to improve the shielding performance of the junction of the high-voltage cable and the high-voltage connector, in order to ensure the reliability of the contact between the two, especially to ensure that the connection will not be loosened under strong movement, the inner conductor of the high-voltage cable and the high-voltage connector After the connection, the cable braid is in contact with the shielding layer, and a separate shielding metal braid is covered at the junction of the cable braid and the connector to enhance the shielding effect. In order to improve the shielding performance of the high-voltage connector itself, the connector adopts a metal shell design. In order to improve the shielding performance at the mating interface of the connector, a shielding spring structure is used in the design to ensure reliable contact between the plug and the socket shell; the inner conductor of the connector head is lower than the shell interface to prevent the inner conductor from contacting fingers or other Metal plays a certain protective role and increases safety; after mating, the shielding layer of the socket connector and the plug connector is in reliable contact, so that the mating surface is shielded from the outside world.
3.2 Mechanical protection and dustproof and waterproof design
Due to the large diameter of the high-voltage cable for electric passenger vehicles, a special wiring direction is required, that is, the high-voltage wiring harness for electric passenger vehicles is laid out outside the vehicle, so the high-voltage wiring harness for electric passenger vehicles must be mechanically protected and dust-proof and waterproof. design. In order to improve the mechanical protection and dustproof and waterproof performance of the high-voltage wiring harness, protective measures such as sealing rings are used between the plugged connectors and the position where the connectors are connected to the cables to prevent the entry of water vapor and dust, so as to ensure the sealing environment of the connectors. Avoid the risk of short circuits between contacts, as well as prevent the ingress of moisture and safety issues such as sparks.
When electric passenger cars drive on the road, they will be affected by factors such as road surface unevenness and vehicle speed, resulting in high vibration, resulting in friction and wear between the high-voltage wiring harness and the contacting components and other wiring harnesses, as well as the fatigue wear of the high-voltage wiring harness itself. . In order to improve the service life and quality of the high-voltage wiring harness, the connection between the high-voltage cable and the high-voltage connector should be reinforced, the connection between the high-voltage connector should be locked, and the wiring scheme should be optimized. Fatigue-resistant stranded copper wire is used. In addition, the connection link between the high-voltage connectors is the weak point of the high-voltage wiring harness itself. In order to improve the service life of the high-voltage wiring harness and meet the use requirements of the high-voltage electrical system, the plugging times and connection quality of the high-voltage connector must be guaranteed.
3.4 Overall structure design
The structure of the final designed electric passenger vehicle high-voltage wiring harness is shown in Figure 5.
4. Performance test of high voltage wiring harness
In order to verify whether the structural rationality, contact area, contact resistance, vibration resistance, etc. of the high-voltage wiring harness designed with high-voltage and high-current contact technology meet the requirements of high reliability, long life and high current performance, samples of high-voltage wiring harnesses for electric passenger vehicles After the development is completed, relevant performance tests are carried out according to the corresponding design requirements, and the test results are shown in Table 1. It can be seen that the performance of the electric passenger vehicle high-voltage wiring harness meets the standard requirements, and the contact structure, connector structure and the design of the entire high-voltage wiring harness have certain rationality.
Main performance test results of high voltage wiring harness
This paper briefly introduces the functional use and domestic and foreign research and development of high-voltage wiring harnesses for electric passenger cars. Starting from the use characteristics, requirements and environment of electric passenger vehicles, the performance requirements and design points (high voltage resistance, high current resistance, environment resistance, shielding, safety and reliability, etc.) of high-voltage wiring harnesses for electric passenger vehicles are analyzed. The main design of the cable, the main design of the connector and its contacts are discussed in detail, and the overall plan of the wiring harness is given. Finally, the test situation of the developed samples is introduced. From the use requirements and test results, it can be concluded that the developed high-voltage wiring harness can meet the use requirements of electric passenger vehicles. With the development of the electric vehicle industry, the high-voltage wiring harness will be further developed, which can withstand higher voltage and current, and will be used in various models. The current and temperature changes of the wiring harness can be monitored in real time.
The above is the common problem analysis of sheathed wire harness processing, silicone wire harness processing, shielded wire harness processing, household appliance wire harness processing, industrial equipment wire harness processing, and medical equipment wire harness processing shared by Hangzhou Assem Electronics Co.,Ltd. If you have more consultation , you can go to our official website, make a phone call, online consultation, we will reply you as soon as possible
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Entering the text, in order to make up for the research gap in the field of high-voltage wiring harnesses for electric passenger vehicles in my country, and to get rid of the current situation that the high-voltage wiring harnesses required in electric passenger vehicles in China are basically directly purchased from foreign products, a high-voltage high-current electric passenger vehicle high-voltage wiring is developed. Independent research and development of beams. According to the use requirements of the high-voltage electrical system of the electric passenger vehicle for the high-voltage wiring harness, the designed high-voltage wiring harness for the electric passenger vehicle should meet the following requirements: a. The usability requirements of high voltage and high current. b. Safety and reliability requirements such as anti-electromagnetic interference, waterproof, anti-vibration, wear-resistant, flame-retardant and reliable contact.
1. Design of high-voltage cables
The traditional wire harness processing manufacturer's car is powered by a gasoline engine. The traditional car cable is used to transmit control signals, and the current and voltage it withstands are very small, so the cable diameter is small, and the structure is only a conductor plus insulation, which is very simple. However, according to the use requirements of high-voltage cables for electric passenger vehicles, the high-voltage cables for electric passenger vehicles mainly play the role of transmitting energy, and the energy of the battery needs to be transmitted to various subsystems. current transmission. The high-voltage cables of electric passenger vehicles are subject to higher voltage (up to 600 V rated voltage), larger current (up to 600 A rated current), and stronger electromagnetic radiation, so the diameter of the cable increases significantly. The equipment produces strong electromagnetic interference, which affects the normal operation of other electronic equipment. The cable is also designed with an anti-electromagnetic interference shielding structure, that is, a coaxial structure is used, and the inner conductor and the outer conductor (shielding) are used together. The magnetic field in the cable is distributed in concentric circles. The electric field points from the inner conductor and ends at the outer conductor, so that the external electromagnetic field around the cable is zero, that is, the electromagnetic radiation is shielded, thereby ensuring the normal operation of the electric vehicle.
Environmental protection wire has the following major characteristics: 1. High flame retardancy, environmental protection wire can ensure its high requirements for fire protection buildings. In case of fire, environmental protection wire can not only be difficult to burn, but also prevent the spread of flames and disasters after combustion. expansion. 2. Halogen-free, the use of green environmental protection edge layer, sheath and special oxygen barrier material, not only makes the environmental protection wire have good electrical properties, physical and mechanical properties, but also ensures that the product does not contain halogen, and solves the problem of formation of its combustion. "Secondary pollution" avoids the "dioxin" substances that can be produced when traditional PVC wires are burned. 3. Low-element, the edge and sheath of the environmental protection wire do not contain lead, cadmium and other harmful heavy metals, and will not pollute the soil and water sources when the environmental protection wire is used and disposed of. And after harsh sex experiments, the mice were safe and sound under the prescribed experimental conditions. 4. No corrosive gas is produced, and new special coating materials that are non-polluting to the environment are used, so that the environmentally friendly wires will not generate HCL and other gases during production, use and combustion, and emit very little acid gas, which is harmful to personnel, equipment and instruments. The damage is small, showing the characteristics of environmental protection. 5. High light transmittance, the smoke generated when the environmental protection wire is burned is extremely thin, which is conducive to the evacuation of personnel and the fire-fighting work. Generally speaking, the light transmittance of environmentally friendly wire products is greater than 40%, which is much higher than the standard of less than 20% light transmittance of traditional flame retardant wires and cables. 6. High protection against UV light or water.
Insulation materials for automobile cables of early wire harness processing manufacturers are mainly PVC (polyvinyl chloride), but PVC contains lead, which is harmful to the human body. XLPE (cross-linked polyethylene), silicone rubber and other materials are replaced. Since the high-voltage cables for electric passenger vehicles not only meet the requirements of high-voltage and high-current, anti-electromagnetic interference, but also wear-resistant and flame-retardant, the properties of these materials are compared:
a. LSZH can be divided into two categories: PO (polyolefin) and EPR (ethylene propylene rubber), among which PO cable material is the mainstream. There are a lot of AI(OH)3, Mg(OH)2 inorganic flame retardants in the formula of PO type LSZH flame retardant cable material, so that the cable material has better flame retardant, low smoke, halogen free, low toxicity, etc. However, it is also different from other non-flame retardant materials and halogen-containing flame retardant materials in terms of physical and mechanical properties, electrical properties and extrusion process properties.
b. TPE is a polymer material with both rubber and thermoplastic properties. It shows the high elasticity of rubber at room temperature and can be plasticized at high temperature. However, the material is not wear-resistant and cannot meet the high-voltage lines of electric passenger vehicles. bundle usage requirements.
c. XLPE is made of ordinary PE (polyethylene) material with a temperature resistance grade of 75 ℃ after being cross-linked by irradiation. Its temperature resistance grade can reach 150 ℃, and it has excellent physical and mechanical properties, overload resistance and Long life and other characteristics, but not flame retardant.
d. The breakdown voltage of silicone rubber is high, so it has arc resistance, leakage trace resistance and ozone resistance. It also has good high and low temperature resistance, high temperature resistance up to 200 ℃, good insulation performance Stable performance and flame retardant under conditions. After comparing the properties of the above materials, silicone rubber has become the first choice for high-voltage cable insulation materials for electric passenger vehicles due to its good physical and mechanical properties, long service life and low price. The structure of the final designed electric passenger vehicle high-voltage cable is shown in the figure:
2. Design of high voltage connector
2.1 Design of high current contacts
Usually the connector (mainly refers to the contacts) has a temperature limit for use. Once the use temperature exceeds the specified limit, the safety of the connector will be reduced due to heat, or even failure and damage. There are two main reasons for the increase in the temperature of the connector:
a. The car itself. The hottest part of the car is around the engine. For example, the temperature around the traditional car engine can reach more than 125 ℃.
b. The connector itself. The connector wiring harness manufacturer will generate heat during use, and the contacts inserted in the connector have contact resistance. The greater the contact resistance, the greater the power loss, the higher the temperature of the contact, and the lower the reliability. In this regard, special attention should be paid when designing high-voltage and high-current connectors for electric passenger vehicles. In order to avoid excessive use temperature to damage the insulating material in the connector, reduce its insulating performance, or even burn out, and reduce the elasticity of the contact after being heated, or form an insulating film in the contact area, reduce the contact reliability, increase Large contact resistance, and then aggravate the use of temperature, such a vicious circle eventually leads to the failure of the connection and contact, and the high-current contacts in the high-voltage and high-current connectors of electric passenger vehicles must be reasonably designed.
When designing high-current contacts, the choice of contact form will directly determine the quality and cost of the connector. Generally, there are three main contact forms of contact pieces: leaf type, leaf spring type and wire spring type, as shown in Figure .
The socket of the chip contact is slotted and closed in a cylindrical cylinder. The socket is processed with beryllium bronze wire (rod), the raw material price is more expensive, and the subsequent closing process is difficult to control, the consistency of product quality is difficult to guarantee, and the cost is high. .
The socket of the contact part of the leaf spring type wiring harness processing manufacturer is a crown spring hole, and there are 1 to 2 leaf spring coils placed in the socket. It has an elastic spring ring; when the socket and the pin are matched, each spring piece is in contact with the pin and produces a pressing force to ensure stable contact at multiple points; the leaf spring socket is made of brass machine parts and crown springs Composed of stamping parts, the product has good consistency and low cost. Amphenol's patented RADSOK socket structure (shown in Figure 3), which uses hyperbolic crown spring technology, increases the contact area by 65%, and has a silver-plated surface for high wear resistance.
The jack of the wire spring contact is a wire spring hole. The structure of the jack is similar to that of the leaf spring jack, but the wire spring jack is composed of spring wires. Although the wire spring jack has excellent performance, the process is complicated. , the cost is also higher.
After comparing the above-mentioned contact types of contacts, the high-current high-current connector for electric passenger vehicles adopts a high-current leaf spring type contact. At the same time, in order to improve the contact reliability and current-carrying capacity, and to meet other index requirements of the high-current contact piece, the high-current leaf spring contact piece adopts a double-reed two-stage leaf spring socket. Finally, through the calculation of the contact resistance of the high-current contact, the design of the structure and the modification of the sample design, the high-current contact is successfully designed.
2.2 Design of high pressure resistance
In order to meet the design requirements of high-voltage connectors for electric passenger vehicles, it is necessary to ensure that all parts of the high-voltage connector have sufficient dielectric strength through structural design and material selection to ensure its high-voltage resistance performance. The high-voltage performance design of high-voltage connectors for electric passenger vehicles mainly includes creepage distance, interface air gap and insulating materials.
The creepage distance means that when the working voltage is too large, the instantaneous overvoltage will cause the current to release the arc along the gap between the insulation, which will damage the device and even the operator. This insulation gap is the creepage distance, and the continuous working voltage of the arc determines the creepage distance. electrical distance. In the structural design of high-voltage connectors, the creepage distance should be increased as much as possible. Considering that the dielectric withstand voltage of the connector is more than 400V, after careful calculation and checking, the creepage distance of the connector is designed to be more than 24mm, which can fully meet the high voltage Connector 600V requirements for use.
In order to improve the high pressure resistance of the connector, when the connector is inserted, its interface should be fitted with no air gap. The interface of the connector mainly includes the mating interface of the plug connector and the socket connector, the connection parts of the connector contacts and the wires. These parts need to be filled with medium without air to reliably ensure that the connector is not broken down. In order to eliminate the existence of the interface air gap, the following measures have been taken in the design of the high-voltage connector:
a. Soft insulating material is used at the insertion interface to ensure that the air gap is filled while the insertion is in place.
b. The insulation outside the jack contacts is in the form of molding, filling the gaps outside the contacts.
c. The mating surface of the plug and socket adopts a tapered structure.
d. Part of the cable insulation after the contact piece connects the cable extends into the connector housing insulation.
In order to improve the high-voltage resistance performance of the connector of the wire harness processing manufacturer, the high-voltage connector of the electric passenger car is selected with good insulation performance, high breakdown voltage, high dielectric strength, good stability under high temperature and high pressure, arc resistance, resistance to leakage traces, and moisture absorption. Low PPA (polyphthalamide) plastic.
2.3 Overall structure design
Figure 4 shows the structure of the electric passenger car high-voltage connector designed by the final wire harness manufacturer. The structure of the high-voltage connector is, from inside to outside, the inner conductor, the insulating layer, the shielding layer, and the outer shell.
3. Overall design of high voltage wiring harness
3.1 Shielding performance design
In order to make the designed high-voltage wire harness not only meet the basic reliable electrical connection requirements, but also have excellent electromagnetic shielding performance, the shielding performance design of the high-voltage wire harness is developed. The shielding performance design of the high-voltage wiring harness mainly includes the shielding performance design of the high-voltage cable itself, the shielding performance design of the junction of the high-voltage cable and the high-voltage connector, the shielding performance design of the high-voltage connector itself, and the high-voltage connector. In order to improve the shielding performance of the high-voltage cable itself, the high-voltage cable adopts a shielding structure. If the cable is composed of a signal line and a power line, more attention should be paid to this point. In order to improve the shielding performance of the junction of the high-voltage cable and the high-voltage connector, in order to ensure the reliability of the contact between the two, especially to ensure that the connection will not be loosened under strong movement, the inner conductor of the high-voltage cable and the high-voltage connector After the connection, the cable braid is in contact with the shielding layer, and a separate shielding metal braid is covered at the junction of the cable braid and the connector to enhance the shielding effect. In order to improve the shielding performance of the high-voltage connector itself, the connector adopts a metal shell design. In order to improve the shielding performance at the mating interface of the connector, a shielding spring structure is used in the design to ensure reliable contact between the plug and the socket shell; the inner conductor of the connector head is lower than the shell interface to prevent the inner conductor from contacting fingers or other Metal plays a certain protective role and increases safety; after mating, the shielding layer of the socket connector and the plug connector is in reliable contact, so that the mating surface is shielded from the outside world.
3.2 Mechanical protection and dustproof and waterproof design
Due to the large diameter of the high-voltage cable for electric passenger vehicles, a special wiring direction is required, that is, the high-voltage wiring harness for electric passenger vehicles is laid out outside the vehicle, so the high-voltage wiring harness for electric passenger vehicles must be mechanically protected and dust-proof and waterproof. design. In order to improve the mechanical protection and dustproof and waterproof performance of the high-voltage wiring harness, protective measures such as sealing rings are used between the plugged connectors and the position where the connectors are connected to the cables to prevent the entry of water vapor and dust, so as to ensure the sealing environment of the connectors. Avoid the risk of short circuits between contacts, as well as prevent the ingress of moisture and safety issues such as sparks.
When electric passenger cars drive on the road, they will be affected by factors such as road surface unevenness and vehicle speed, resulting in high vibration, resulting in friction and wear between the high-voltage wiring harness and the contacting components and other wiring harnesses, as well as the fatigue wear of the high-voltage wiring harness itself. . In order to improve the service life and quality of the high-voltage wiring harness, the connection between the high-voltage cable and the high-voltage connector should be reinforced, the connection between the high-voltage connector should be locked, and the wiring scheme should be optimized. Fatigue-resistant stranded copper wire is used. In addition, the connection link between the high-voltage connectors is the weak point of the high-voltage wiring harness itself. In order to improve the service life of the high-voltage wiring harness and meet the use requirements of the high-voltage electrical system, the plugging times and connection quality of the high-voltage connector must be guaranteed.
3.4 Overall structure design
The structure of the final designed electric passenger vehicle high-voltage wiring harness is shown in Figure 5.
4. Performance test of high voltage wiring harness
In order to verify whether the structural rationality, contact area, contact resistance, vibration resistance, etc. of the high-voltage wiring harness designed with high-voltage and high-current contact technology meet the requirements of high reliability, long life and high current performance, samples of high-voltage wiring harnesses for electric passenger vehicles After the development is completed, relevant performance tests are carried out according to the corresponding design requirements, and the test results are shown in Table 1. It can be seen that the performance of the electric passenger vehicle high-voltage wiring harness meets the standard requirements, and the contact structure, connector structure and the design of the entire high-voltage wiring harness have certain rationality.
Main performance test results of high voltage wiring harness
This paper briefly introduces the functional use and domestic and foreign research and development of high-voltage wiring harnesses for electric passenger cars. Starting from the use characteristics, requirements and environment of electric passenger vehicles, the performance requirements and design points (high voltage resistance, high current resistance, environment resistance, shielding, safety and reliability, etc.) of high-voltage wiring harnesses for electric passenger vehicles are analyzed. The main design of the cable, the main design of the connector and its contacts are discussed in detail, and the overall plan of the wiring harness is given. Finally, the test situation of the developed samples is introduced. From the use requirements and test results, it can be concluded that the developed high-voltage wiring harness can meet the use requirements of electric passenger vehicles. With the development of the electric vehicle industry, the high-voltage wiring harness will be further developed, which can withstand higher voltage and current, and will be used in various models. The current and temperature changes of the wiring harness can be monitored in real time.
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