EVCOME EV charging stations for better life---Top EV charging stations manufacturers & suppliers in China.
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EVCOME EV charging stations for better life---Top EV charging stations manufacturers & suppliers in China.
High-voltage cables for new energy vehicles are generally composed of high-voltage cables, connectors, protective materials (insulation pipes, braided pipes), brackets (or rolled strips), sealing rubber rings, tapes, heat shrinkable tubes, labels, etc. High-voltage cable conductor, insulation, sheath, shielding, aluminum foil, tape, filler, etc. The industry standard refers to "QC-T1037 Road Vehicle High Voltage Cable Automotive Industry Standard" and "New Energy Vehicle TCAS356-2019". Features: high voltage (passenger cars generally use rated voltage 600VAC/900VDC, commercial vehicles generally use rated voltage 1000VAC/1500VDC), high current (usually 250A, some high-power motors can use 400A). 1. The conductor is composed of annealed soft copper wire or tinned copper wire. The difference between soft copper wire, hard copper wire and tinned copper wire is as follows. Hard copper wire: cold processed by stretching wire, high tensile strength, suitable for conductors of overhead transmission lines, distribution lines and construction lines; soft copper wire: hard copper wire is heated to remove residual stress caused by cold processing, soft bending, high conductivity High, used in the manufacture of communication and power cable conductors, electrical machinery and various household appliances; tinned copper wire: the surface of the copper wire is tinned to increase weldability and protect the copper conductor from corrosion during PVC or rubber insulation deposits , to prevent aging of rubber insulation. Tinned copper wires are generally used for high-voltage cables with a temperature resistance rating above 150°C. At present, most of the conductors in the new energy automobile industry use oxygen-free copper wires, that is, copper wires with an oxygen content of less than 0.001% and extremely high purity. The copper content is above 99.99%, and will not be embrittled by oxygen. The flexibility of high voltage cables is mainly determined by the design of the conductors. This is why high voltage cables use a large number of special conductors with very small diameter monofilaments. The conductor is bound by a certain number of monofilaments, and then twisted concentrically to form the soft conductor required by the high-voltage cable. Another advantage of multiple roots is better resistance to bending. Shorter strand spacing can also improve the flex life of high voltage cables. The high-voltage cable conductor strand pitch and conductor diameter used in the high-voltage wire harness of the vibration source directly affect its bending resistance. Generally speaking, the smaller the diameter of individual conductors, the shorter the pitch, which can improve the bending life of high-voltage cables. Specific parameter settings need to be verified according to the conditions of use. The conductor specifications of high-voltage cables are divided according to the cross-sectional area. At present, the commonly used specifications in the new energy industry range from 1.5 square meters to 120 square meters, and the diameters of single wires or single conductors vary. The structural dimensions and resistance of copper conductors are shown in the table below. (Note: Cross-sectional area of high-voltage cable conductor = cross-sectional area of single wire×The number of conductors) The nominal cross-sectional area is the code to guide production and design. The cross-sectional area of the electrical performance of the cable is based on the conductor resistance, which can be understood as the conductor resistance is within the range of the nominal cross-sectional area, but the error of the conductor cross-sectional area can also be regarded as the nominal specification cable; since the conductor resistance and the conductor cross-sectional area are range values, The outer diameter of the conductor can be confirmed according to the supply and demand communication, and the number of conductors is also different. 2. Insulation and sheath materials. Low-smoke halogen-free cross-linked polyolefin, silicone rubber halogen-free cross-linked polyolefin, silicone rubber material, fluoroplastic material, etc. Thermoplastic material: This material can be softened or liquefied quickly when heated, and can be softened and molded after heating after molding, such as PVC, TPE, etc. Thermosetting plastics: After curing and forming, reheating cannot soften and form, such as XLTPE, XLTO, etc. At present, the advantages and disadvantages of high-voltage cable insulation and sheath design schemes are as follows: Cross-linking is the conversion of polymer polymers from chain-like thermoplastic materials to three-dimensional network-like thermosetting materials. Thermoplastic materials melt and flow when heated, and the processing of cable insulation or sheathing takes advantage of this property; thermoset materials&127; (cross-linked polymer) will not melt and deform at high temperatures, and cannot be extruded, but it has the advantages that thermoplastic materials do not have: molecular chain segments are cross-linked, that is, not only twisted into ropes, but also huddled into groups, so the mechanical properties Excellent; good long-term heat resistance, stable product size; chemical corrosion resistance. There are three cross-linking methods used in the cable industry: peroxide cross-linking method (CV method); silane cross-linking method (SV method) and electron beam cross-linking method (or radiation cross-linking method). Selection of mechanical requirements: The temperature classes are defined below. At present, 125°C cables are generally used, 150°C cables are used for drive motor high-voltage cables, and 180°C is generally used for silica gel. Hardness, wear resistance, bendability, etc. have different requirements for sheath materials. The main parameters of current-carrying capacity cable selection include: current-carrying capacity characteristics, conductor resistance, thermal resistance, temperature resistance, etc., which can be designed and selected according to the cable temperature rise and current-carrying capacity curves in the manufacturer's data, or based on empirical parameters. There will be short-term overload when the motor load is running, so when selecting cables, it should be considered whether the current carrying capacity meets the long-term operating conditions of the vehicle. The duration of cable overcurrent is relatively short, and the heat spreads out less. Therefore, it cannot be considered. According to the current-carrying characteristic curve of the cable and the carrying capacity of the design specification, we found that the high-voltage cable is relatively conservative in the design and selection process, and it is used in the whole vehicle working condition (except for the charging process). The working current of high voltage cables is mostly lower than the rated current. In the application, we found that the current-carrying weakness of the high-voltage wire harness lies in the terminal crimping part, as shown in the figure below, the thermal imaging results during the test, therefore, the selection of the high-voltage wire harness should comprehensively consider the terminals and connectors. The power cycle test verifies its current carrying capacity, and the temperature rise is less than 55K. Lifetime Vehicles typically have a useful life of more than ten years. The service life of a commercial vehicle is a considerable amount of operating time. A typical bus is expected to have a service life of over 50,000 hours. Something happens and the material starts to age through a process called oxidation. All materials oxidize and degrade over time. Due to aging, the cable's insulation eventually becomes brittle, no longer provides sufficient insulating capacity, and eventually shorts out. As the temperature increases, the aging process accelerates. High voltage cables require insulating materials that can slow down the aging process at high temperatures. Compared with ordinary cables, the service life of XLE products is increased by 100-1000 times. Unlike normal battery cables, HEVs and EVs conduct current almost all of the time. Electric current generates heat by conductor resistance. The heat generated by the current heats the cable from the inside out. If the cable is heated from the exposed outside, it will age as quickly as the cable is heated on the inside. .
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