Characteristics and optimization of electric vehicle high voltage cable

The perfect and complex design and use of high-quality materials will result in expensive acsr cable costs. Experience shows that, for specific high voltage cables, it can be tailored by optimizing the cross section, temperature requirements, flexibility and shielding effect. Weight and cost savings can be highlighted, and over sized and over sized components can be avoided.
1. optimization of sectional area and temperature grade
The selection of cables is mostly based on the ambient temperature and the transmission current index. In this regard, the most important features are “cable section” and “heat resistance grade of materials used for cables”.
The voltage drop of the conductor is converted into the conductor of the high voltage cable heated by heat energy. This heat can be partially transferred to the environment, which reduces the operating temperature of the conductor. Lower temperature gradients can transfer less heat. Cables with continuous load current can cause the highest rated temperature to be borne. This temperature can cause the aging of the materials used.


The challenge for cable designers is to design the most suitable cable for application: excessive conductor specifications can lead to increased cost and weight, and larger outer diameter. In the worst case, only considering the highest possible load current and ambient temperature will result in the use of large section cables, high temperature resistant materials such as organic fluorine or silicon.
It is very meaningful to determine the relationship between current and load environment temperature from the technical and economic point of view. The real driver periodic dynamic current peak should be considered, allowing for a reasonable definition of the load current and peak current in the worst case.
A good design prerequisite is an understanding of the basic conditions, such as the need to determine the ambient temperature and cable load first.
Generally, the high-voltage cable manufacturer with large cross-section has a large inertia in terms of temperature change, so the peak current of acceleration or deceleration of vehicles will not cause the influence of a large conductor temperature.
The ability of high voltage cables to handle these peaks is usually defined by thermal overload performance, even if the short-term temperature peaks are allowed to exceed the cable temperature level defined above. Therefore, the cable does not need to be designed as a higher working temperature level, and it is unnecessary to use cables that exceed the specified working temperature.
The permanent load current and single pulse or series pulse can be considered comprehensively, together with various parameters, such as ambient temperature.
The combination of theoretical basis and practical experience can preliminarily determine, select and optimize the high voltage cable which meets the application.


2. flexibility optimization
The available space for the cable routing of the vehicle should be considered carefully. The bending radius of the vehicle in a specific area will lead to the improvement of the flexibility requirements of the whole cable. If small changes may be made in the overall design, it is very meaningful to avoid the problem of tight bending.
Cables do not have to be of the highest flexibility. The exact definition of bending force, combined with the structure and corresponding test equipment, enables the designer of the cable to create the most suitable application design. Especially for larger section cables, it is significant to reduce the cost by replacing the high flexibility design with flexible or conventional structural design.
3. optimization of shielding effect
The shielding effect defined in a certain frequency range is very necessary for the development of cables. Shielding effects without frequency information are not useful, which may lead to excessive size and expensive combination shielding for the solution, which is no longer necessary from a technical point of view.
Generally, the electric vehicle cable development and design stage can be considered by theoretical calculation. Then the shielding effect of high voltage cable is verified by means of test.
Concluding remarks
The high voltage harness of electric vehicle and traditional wiring system still have a long way to go. Specific specification requirements are usually not clearly defined, which can lead to technical complexity, and thus lead to expensive solutions.
All parties involved in the development stage must adopt system oriented method to optimize the technology and cost of high voltage cable reasonably.


These parties may include cable, connector and component suppliers, harness plants, and host plants.
The knowledge accumulation of the whole system and the specification of a high voltage cable which is oriented to the target requirements are the basis of the optimization design.
The R & D Department of cable manufacturing uses theoretical calculation and appropriate measuring equipment to verify that it is capable of developing more suitable cables for application.

How to Ensure Outdoor Cable Performance ?

Many users and installations are faced with the problem of cheap and efficient data transmission between buildings in the park environment. The choice of routing, transmission distance and application environment will all affect the choice of cable medium. Incorrect or inappropriate choice will result in a shortened period of wiring investment, and reinstallation will also cause the network system to stop running.
If it is an outdoor application, the fiber optic system is usually the choice for campus network connection. The real cost of optical fiber lies in the termination of optical fiber cabling system and optoelectronic equipment. When users only need to transmit 10Mbps or 100Mbps within a distance of 50 meters between buildings, optical fibers are generally not used.

Buying conventional Category 5 copper cables underground or laying overhead may cause transmission failure of a certain network along the wiring line. Therefore, choosing the existing outdoor direct-buried enhanced type cable will bring a cheap link. Before deciding to choose these outdoor LAN cables, you should fully understand their design.

Anti-moisture protection nets have been used in communication cables for many years. These aluminum polymer materials have overlapping seals as protection to reduce the penetration path of water vapor to prevent water from entering. However, an unprotected dry cable will need to suffer as long as six months to a year of liquefaction due to infiltration, and a dry cable with a moisture-proof protective net will be completely protected. The cable designed in this way is approximately similar to a foil-screened LAN cable, and it is easy to connect and use.

Therefore, the wiring system designer must consider the application environment, which includes the following environment and parameters that affect the cable:
1. Whether the cable is placed under the eaves; as long as the cable is not directly exposed to sunlight or ultra-high temperature, the standard LAN cable can be used. It is recommended to use pipes:
2. External walls; avoid direct sunlight on the walls and man-made damage;
3. In the pipe (plastic or metal); if in the pipe, pay attention to the damage of the plastic pipe and the heat conduction of the metal pipe;
4. For suspended applications/overhead cables, the sag and pressure of the cable should be considered. Which bundling method you intend to use. Whether the cable is directly irradiated by sunlight; laying directly in the underground cable trench, this environment is the smallest control range. The installation of the cable trench should be checked regularly for dryness or humidity;
5. Underground pipeline. In order to facilitate future upgrades, cable replacement, and isolation from surface pressure and the surrounding environment, laying pipes is a better method. But don’t expect that the pipe will always remain dry, which will affect the choice of cable types.

Factors affecting cable performance include:
1. Ultraviolet (UV)-Do not use cables without UV protection in direct sunlight. You should choose cables with black polyethylene or PVC sheaths, such as Brand-Rex’s 4 pairs of reinforced type 5 MegaOutdoor outdoor cable, with metal mesh moisture-proof protective layer and black polyethylene sheath, is suitable for most inter-building connections, whether it is overhead laying, ground installation or pipeline construction, it can be used:

2. Heat-the temperature of the cable in the metal pipe or trunking is very high. Many polymer materials will reduce the service life at this temperature. Black polyethylene or PVC sheathed power cable should be selected;

3. Water-Water is the real killer of LAN cables. The moisture in the twisted-pair cable of the local area network will increase the capacitance of the cable, thereby reducing the impedance and causing near-end crosstalk problems. If it is extremely effective to prevent moisture and water vapor, a protective layer of metal shielding net is required;

4. Mechanical damage (repair costs)-the repair of optical cables is very expensive, and at least two terminations are required at each discontinuity;

 

Grounding-if the shielding layer of the cable needs to be grounded, the corresponding standards must be followed;

The total length of the route (not only between the buildings)-Use outdoor-grade LAN twisted-pair cables between the buildings, and the total length should be limited to 90 meters.
For a network of 100Mbps or 1000Mbps, the laying distance cannot exceed this limit. If the laying distance is between 100 meters and 300 meters, optical cable should be selected.
The following simple experiments can be used to self-test whether the wiring investment is safe: use a 20-meter enhanced category 5 UTP cable to terminate at both ends; carefully remove the cable sheath at the midpoint of the cable to expose a small section of copper cable (1 cm ); Test the cable according to AN/NZSD standard; soak the cut part of the cable in water for 1-2 minutes, and then retest.