The Key Role of Connectors in New Energy Vehicles: The Core Pillar of Power and Signal Transmission
Connectors are one of the basic components of modern industry and information society. Connectors are rich in variety and models. As nodes between electronic system devices, they transmit current or optical signals between devices, equipment, components, and subsystems, and ensure signal integrity and energy transmission efficiency between systems. Connectors in different application fields need to meet different performance requirements, and their functional characteristics and technical levels vary depending on the application scenario. According to different transmission media, connectors can be divided into electrical connectors, microwave radio frequency connectors, and optical connectors, which are widely used in communications, automobiles, consumer electronics, industrial transportation, aerospace, and military fields.
Different types of connectors have different functions, which leads to differences in the design and manufacturing requirements of different types of connectors. Generally speaking, electrical connectors need to meet the requirements of good contact and reliable operation. Among them, when transmitting high-power electric energy, low contact resistance, high current carrying capacity, low temperature rise, and high electromagnetic compatibility are also required; when transmitting high-speed data signals, good circuit impedance continuity, small crosstalk, low delay, and high signal integrity are required. In addition to the requirements for contact reliability, microwave RF connectors have strict requirements for impedance design and compensation, and need to meet performance requirements such as insertion loss, return loss, phase, and third-order intermodulation. Optical fiber connectors have strict requirements for the alignment accuracy of components, so they require high processing accuracy of contact parts, high cleanliness, and accurate positioning. In addition, connectors generally need to meet basic performance requirements such as mechanical performance, electrical performance, and environmental performance.
The connector consists of contacts, insulators, shells and accessories. The contacts are the core components of the connector. Electrical connection is achieved through the insertion of male and female contacts. The male contacts are rigid parts, usually made of brass or phosphor bronze, while the female contacts are sockets. Through the elastic structure, elastic deformation occurs when the pins are inserted, forming a close contact with the male contacts. The insulator plays an insulating role between the contacts and between the contacts and the shell. The shell, as the shell of the connector, provides protection and alignment during insertion. Accessories are divided into structural accessories (such as clamps, positioning keys, positioning pins, guide pins, sealing rings, sealing pads, etc.) and installation accessories (such as screws, nuts, screws, spring coils, etc.). According to the prospectus data of Recorda, structural parts are the link with the highest cost in connectors, accounting for about 42% of the cost of structural parts.
The connector industry chain is divided into upstream raw materials, midstream manufacturing and downstream applications. The upstream covers metal materials and electroplating materials for manufacturing terminals, plastic materials and structural materials for manufacturing insulators and shells, etc. The midstream is the manufacturing process of connectors, including lathe processing and electroplating of metal materials, production and molding of plastic materials, die-casting and electroplating of structural materials, and then through manufacturing, assembly and testing, the finished connectors are manufactured. The downstream applications are extensive, covering communications, automobiles, consumer electronics, industrial transportation, aerospace and military fields.
From the perspective of downstream fields, automotive connectors are widely used in various subsystems of automobiles. Automotive connectors can be divided into low-voltage/high-voltage connectors for transmitting current and high-frequency and high-speed connectors for transmitting data signals. With the trend of electrification, intelligence and networking of automobiles, automotive electronic applications will penetrate from mid-to-high-end models to low-end models, and their share in the manufacturing cost of the whole vehicle will continue to increase, and the demand for automotive connectors will also increase day by day. As the signal hub connecting various electronic systems, automotive connectors are widely used in power systems, body systems, information control systems, safety systems, on-board equipment, etc., acting as the “blood vessels” to maintain the normal operation of automobiles.
High-voltage trend: The frequent launch of 800V platform models has driven the growth of demand for high-voltage connectors.
High-voltage connectors play a key role in connecting high-voltage system units and transmitting energy in electric vehicles. Traditional vehicles are driven by mechanical energy generated by the engine, while electric vehicles are powered by power batteries and motors. At present, the charging voltage of most electric vehicles is 400V, which is significantly different from the 12V or 24V voltage of traditional vehicles. Many system units in electric vehicles need to work under high voltage and high current conditions, such as batteries, motors, transformers, OBCs, PDUs, air conditioning compressors, heaters, and charging interfaces. These system units need to be connected using high-voltage connectors. Compared with low-voltage connectors, high-voltage connectors need to withstand higher voltages, have greater current carrying capacity, and have electromagnetic shielding characteristics in terms of electrical performance.
High-voltage connectors are mainly composed of four parts: contactor, insulator, plastic shell, and accessories. The contact parts include male and female terminals, springs, etc., which are the core parts for completing electrical connections; the insulator mainly refers to the inner plastic shell, which is used to support the contact parts and ensure the insulation between the contact parts; the plastic shell mainly refers to the outermost plastic shell of the connector, which is used to protect the entire connector; the accessories can be divided into two types: structural accessories and installation accessories, including positioning pins, guide pins, connecting rings, sealing rings, rotating levers, locking structures, etc.
The upgrade of high-voltage connectors revolves around the high-voltage interlocking function. With the development of new energy vehicles, high-voltage connectors have undergone several upgrades. From the perspective of connectors, the high-voltage connectors modified from industrial connectors are the first generation, and the high-voltage interlocking function began to be applied in the second generation. The third-generation high-voltage connector is characterized by plastic + shielding function + high-voltage interlocking. The fourth-generation high-voltage connector adds a secondary unlocking function on the basis of the third generation.
High-voltage connectors have a high technical threshold. The structure of high-voltage connectors is complex, and it is necessary to fully consider the stability and safety between the terminal and the wire, between the male and female terminals, between the terminal and the ferrule, and between the male and female connectors, as well as to ensure the integrity and continuity of the high-voltage circuit.
1. High-voltage interlock. Use low-voltage signals to manage high-voltage circuits. Through the logic sequence of high-voltage interlock, the connector system with high-voltage interlock can be disconnected when energized. The power terminals and interlock terminals will be connected/disconnected in sequence to ensure the safety and reliability of the high-voltage connection system.
2. Secondary locking. It includes two parts: main locking and auxiliary locking. When connecting, the main locking is performed first, and then the auxiliary locking; when disassembling, the auxiliary locking needs to be unlocked first, and then the main locking is unlocked. Through this nested design, the connection can be effectively prevented from being loosened by external interference. The secondary locking structure includes CPA between connectors and TPA between terminals and ferrules.
3. Spring structure. It mainly includes leaf spring type, wire spring type and spring coil type. The leaf spring structure has a simple process, but the contact stability is average and the contact resistance is high; the wire spring structure has a soft plug-in force and a long life, and is resistant to vibration and impact, but the process is complex, the cost is high, and the volume is larger. It is currently only suitable for round terminals; the fan leaf spring in the spring coil structure has more than 40 contact points with the female terminal, and the contact resistance is low, but the processing technology is difficult and the cost is high, and it is generally suitable for round terminals.
High-voltage fast-charging technology is constantly improving, and the 800V high-voltage platform drives the demand for high-voltage connectors. Mileage + energy replenishment Anxiety is the main problem of new energy vehicles. With the continuous improvement of the energy density of power batteries, the long charging time has become the biggest pain point.
There are two ways to improve charging efficiency: voltage and current. The high-current charging process will generate a lot of heat, and the thermal management requirements are higher. At the same time, a thicker wiring harness is required, and the maximum power charging time is short. In comparison, the high-voltage solution has lower requirements for thermal management and wiring harness costs, and most new energy vehicle companies choose this solution.
Using the 800V high-voltage platform of all vehicle components can not only increase the charging power, but also significantly reduce the current while the output power of the vehicle motor remains unchanged, thereby effectively reducing heat loss; significantly reducing the wire harness diameter and reducing the overall vehicle load. weight and improved cruising range. The 800V high-voltage platform places higher requirements on the quantity and quality of high-voltage connectors inside electric vehicles, and also promotes the development of charging guns in the direction of high power and liquid cooling.
OEMs are accelerating their fast charging layout, and companies are following up on the 800V high-voltage platform. In the past two years, the high-voltage fast charging route has been favored by more and more OEMs. International giants such as Hyundai and Kia have released 800V high-voltage platforms. Later, emerging car companies such as BYD, Jikrypton, GAC, Xpeng, and Ideal have also begun to deploy 800V models. . In addition, Tesla, Xpeng, GAC, etc. are also actively deploying supporting super charging piles.
Intelligent development: The increasing transmission requirements of intelligent driving clearly point to the trend of high-frequency and high-speed connectors
High-frequency and high-speed connectors belong to microwave radio frequency connectors. Unlike high-voltage and low-voltage connectors that transmit current, they are mainly used for high-speed signal transmission. High-frequency and high-speed connectors can be divided into two categories: coaxial connectors and differential connectors. The former connects coaxial cables and mainly transmits analog signals, including Fakra and Mini-Fakra (HFM); the latter connects twisted pair cables and mainly transmits digital signals, including HSD and Ethernet connectors.
At present, the most commonly used high-frequency and high-speed connector in traditional passenger cars is Fakra. Fakra is generally used for the installation and connection of sensors and is the standard interface for high-frequency applications in automobiles. Mini-Fakra is used as a transmission medium between sensor data and AVM systems due to its good integration performance. HSD is mainly used for high-speed transmission from AVM to the host end and from the host end to the cockpit end. In-vehicle Ethernet is used as the backbone network for in-vehicle communication, connecting various subsystems inside the vehicle end. High-frequency and high-speed connectors cover many application scenarios, from the most basic body control and positioning systems to 4K cameras, high-definition video, infotainment, assisted driving, intelligent driving, etc.
New energy vehicles are developing rapidly in the direction of intelligence, and the autonomous driving system is constantly iterating and upgrading. Referring to the International Society of Automotive Engineers (SAE), autonomous driving is divided into 6 levels from L0 to L5, and the higher the level, the higher the maturity of autonomous driving. Among them, L0 is emergency assistance; L1 is partial driving assistance; L2 is combined driving assistance; L3 is conditional automatic driving; L4 is highly automatic driving; L5 is fully automatic driving.
The tasks of monitoring road conditions and responding to L0 to L3 are completed by the driver and the system, and the driver needs to take over the dynamic driving task, while L4 and L5 can completely transform the driver into the role of a passenger.
The demand for autonomous driving and entertainment places higher demands on the quantity and quality of high-frequency and high-speed connectors. As the autonomous driving system continues to iterate to L3, the number of sensors (cameras, millimeter-wave radars, and lidars, etc.) and the expansion of functional requirements such as parking assistance, lane departure warning, night vision assistance, adaptive cruise control, collision avoidance, blind spot detection, and driver fatigue detection are constantly increasing, prompting ADAS (advanced driver assistance) to be equipped with a higher bandwidth transmission network.
At the same time, cockpit entertainment has gradually become a new product direction for smart cars. The connection of automotive infotainment such as the central control screen, rear screen, car windows, and 4K video requires high information transmission rates and high-performance time synchronization information flows. Massive data has spawned more and faster demand for high-frequency and high-speed connectors.
In line with the trend of high-bandwidth and large data packets, Mini-Fakra is expected to gradually replace Fakra. Fakra connector is a standard interface for high-frequency applications in automobiles, with the most mature technology, and is widely used in data transmission of antennas, GPS, and on-board cameras below 2MP (1080P).
With the continuous deepening of automobile intelligence, Fakra has the disadvantages of small data transmission volume, large structural parts, and inability to meet the current mainstream architecture interface protocol. As the next generation of coaxial connectors in the automotive industry, Mini-Fakra has a maximum transmission frequency of 20GHz and a maximum transmission rate of 28Gbps, and can support multiple on-board cameras with specifications above 8MP (4K).
At the same time, Mini-Fakra is smaller in size and more integrated. If it replaces Fakra, which occupies a larger space, it can save up to 80% of the installation space, reduce the weight of the wiring harness, and achieve cost optimization. Mini Fakra is expected to gradually replace traditional Fakra in the next few years.
In-vehicle Ethernet connects various subsystems inside the vehicle and will become the core link of automotive intelligence. Traditional in-vehicle networks such as CAN and LIN can no longer meet the transmission needs of massive data under the trend of automotive intelligence. Autonomous driving and in-vehicle entertainment bring hundreds of times more data than traditional cars, and will continue to increase with the deepening of intelligence.
Compared with traditional in-vehicle networks, Ethernet can meet the needs of higher transmission rates while reducing the use of connectors and wiring harnesses to reduce costs and weight, conforming to the trend of lightweighting. Ethernet connectors have the advantage of modularity and are widely used for communication connections between domain controllers and between modules within a domain.