Power Line Communication Reduces Wiring Harness Weight in Hybrid and Electric Automobiles
The concept of e-mobility is a very powerful one in the automotive industry. Automakers and governments are increasingly turning to e-mobility solutions. Witness the incredible explosion of hybrid vehicles now flooding the marketplace and the increasing number of automakers investing in all-electric designs. Governments are often the driving power here, mandating lower and lower emissions, reductions in greenhouse gases emitted from vehicles and a reduction in the consumption of fossil fuels.
There are several hurdles that need to be overcome in the automotive industry to reach these goals. These include lowering the weight of vehicles, as well as developing more advanced technology to make all-electric vehicles a more viable alternative for all drivers.
The Major Hurdle for the Automotive Industry
Perhaps the most significant challenge for the automotive industry to overcome is that of weight. The weight of a vehicle determines several different things. For instance, the heavier a vehicle is, the more power it requires to move. It requires more force to move a heavier vehicle to operating speed than it does a very light vehicle.
This need for more power results in higher greenhouse gas emissions, as well as in more consumption of fossil fuels. Additionally, it results in shorter charges for all-electric vehicles and increased charging needs (higher performance equates to a higher drain on the vehicle’s batteries).
To overcome the problem of weight, automakers have taken several different steps. For instance, the widespread use of aluminum in body construction and in component construction is one way of reducing vehicle weight. Another shift is the slight change in size with hybrid and electric vehicles. The majority of these vehicles are smaller than their standard ICE counterparts are.
However, there is one shift in automotive technology and manufacturing that needs to be made. While there have been strides made in this area, more is on the way. The area in question is that of the automotive wiring harness.
The Problems with Modern Automotive Wiring Harness Designs
The modern wiring harness is an integral part of the vehicle. It provides communication and electricity throughout the vehicle. This ranges from providing electricity to the interior lights to powering and communicating with the ECM. As such, it is vital. However, it is also a problem.
The problem with wiring harnesses is that they are very heavy. The sheer length of wire needed to create even an average harness is immense. Add to that the fact that those automotive cables are mostly made from copper and it adds hundreds of pounds to a vehicle in some instances.
Changes Coming for Automotive Wiring Harness Design
There are quite a few changes on the horizon for automotive wiring harness design. One of those currently being researched and studied is replacing copper with aluminum. Aluminum offers significant advantages, in that it is far more affordable than copper, and it also weighs far less.
Another change that is coming is the technology to use power line communication to reduce the size and weight of the wiring harness in automotive applications. There are several benefits here.
The Components of a Wiring Harness
A standard wiring harness uses different wire for communications and for power, even though the same wires run to the same devices. For instance, a power wire runs to the ECM, as well as to the airbag unit and the PCM. However, each of those devices also has a separate automotive cable for communications.
The reasoning behind this design is the fact that power lines are often “noisy.” That is, pulses generated by loads on the power line make communication difficult or impossible in many situations. However, modern technology has allowed manufacturers to overcome this hurdle in unique ways.
Using DC-BUS technology, communications can be sent via the same lines that carry power in the wiring harness. This offers significant advantages for automakers, as well as for end consumers.
Cost Reduction: One of the most significant benefits here is the cost reduction for wiring harness manufacture. Because there are fewer wires involved in creating the wiring harness, the construction costs are greatly reduced. This offers automakers considerable savings, but also provides savings to end consumers, as those savings can be passed along from the automaker to their customers.
Faster Installation: In automotive manufacturing, installing the wiring harness is one of the most time-consuming tasks. This is due to several factors, including the complexity of the task, itself. However, using this advanced technology, installation time and costs can be reduced by a significant amount. This increases production and to-market speed, while simultaneously reducing labor costs involved with manufacturing.
Reduced Weight: Perhaps the most significant factor of this new technology is that it reduces the weight of automotive cables by a drastic amount. Less weight has immense implications for all aspects of automotive technology, from design to manufacturing to use. Reduced vehicle weight provides better fuel economy in hybrid vehicles, and allows a single charge to last longer in electric vehicles. In addition, lighter vehicle weight equates to reduced emissions, as well.
Multiple Communication Channels: Another benefit of routing communication and power through the same automotive cables is the fact that multiple communication channels can be produced. These include mechatronics, telematics and multimedia communications, with speeds up to 1.7Mbps and up to 16 nodes per channel.
Ease of Modification: Because standard wiring harness design requires both power and communication cabling, modifying an existing system can be difficult and costly. However, this new technology offers simplicity of modification, as there is only a single battery connection required. All cables carry both power and communications, so modifications can be made with considerable ease.
Why It Matters
While the reduction of weight, fuel costs, emissions and other considerations listed previously are reason enough for this technology, there are other considerations to be made. Currently, 18% of a vehicle’s entirety is electronics. However, that is expected to change to 50% in a very short time. This applies to standard ICE vehicles.
Other vehicles, such as hybrids, will also see an increase, while electric vehicles will see an increase in electrical loads placed on the system. The greater the number of electronic devices present within an automobile, the greater the complexity of the wiring harness. However, by communicating over power cables, that complexity (and the related weight and costs) can be reduced significantly.
In addition, this technology is quite capable of handling the 42v system that is now being implemented. Existing wiring harness applications will require severe modifications and redesign to combat problems created by carrying higher voltage, though.
Applications for Communication over Power Cables
There are many applications for communication via power cables in an automotive system. These were touched on previously, but they bear greater examination.
Multimedia: This is perhaps the largest trend in the automotive accessory segment. More and more frequently, consumers are demanding access to multimedia functionality in their vehicles. This includes features such as MP3 player integration, CD/DVD changers and players, computer connections, advanced entertainment and more. Communication via automotive cables that supply power offers speeds and transfer rates ideal for all multimedia applications.
Telematics: This offers benefits for digitized voice and data communication throughout an entire vehicle. Applications such as built-in navigation systems and even Internet connectivity benefit here, as data throughput in the range of 250Kbps is possible. This also allows communication between the vehicle and a towed trailer or other arrangement.
Mechatronics: One of the hallmarks of the modern automotive industry is the number of sensors now in use. These range from TPMS systems to smart battery indicators, security systems, obstacle detection systems, automated climate control sensors and more. Mechatronic systems such as these can communicate very effectively via automotive cables that supply power, as they require a lower data throughput rate. Protocols like J1850 and CAN can be supported by this technology.
In summation, changes lie ahead for automotive cables and wiring harnesses. These include several different things, including the development of viable aluminum wire systems and connectors, as well as the implementation of technology that allows data connection over cables that supply power.
The benefits offered by data-over-power technology are considerable, and have ramifications for any devices connected to the vehicle’s wiring harness that need more than just power supplied (the vast majority of systems). In addition, that need will continue to grow as electronics come to make up more and more of the average automobile.
As the 42-volt automotive system becomes the standard, communication via DC power cables will become more and more important. As government regulations continue to restrict emissions, fuel consumption and other factors, vehicle weight will continue to be a consideration. Routing communication through automotive cables carrying power offers significant advantages to automakers and designers, as well as to the customers who will ultimately purchase the vehicles.
While this technology is still in testing for mass production and applicability, it will be the way of the future for automakers intent on providing the best possible product while remaining in compliance with government regulations.
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