AUTONOMOUS TECHNOLOGY FORCES US TO RETHINK OF CAR ELECTRICAL SYSTEMS

There's nothing more frustrating than a technology failure in your car – pressing a button, turning a knob and having nothing work at all.

With self-driving, autonomous cars driving into our near future (many having a 48-volt system in the powertrain) these failures just cannot happen. The slightest error – in a camera, radar or lidar unit could cause fatal accidents. Even a short-circuit in the battery pack could cause a fire. 

In an effort to understand where and why failures occur and part of an industrywide push to banish electrical problems, Delphi engineers have been studying electrical gremlins in automobiles on the road by looking at warranty data. 

Delphi has been taking with French and German automakers and, by year end, may have a better idea of how next-generation electrical systems will be configured.  

One shocking finding from Delphi's research is that connectors fail not because of corrosion from moisture, improperly seated terminals that work loose during driving or improperly crimped or damaged wires. 

In fact, the research has indicated, connectors fail and take a vehicle's electronic accessories down mainly as a result of mistakes made during assembly. The main reason for electric failure is because both parts of the plastic housing that hold the wire terminals are not fully mated, according to Delphi. 

So how will the industry eliminate electrical problems in self-driving vehicles with high-voltage powertrains? 

Well, you may think the answer is simple: design foolproof wire connectors and flawless assembly methods so that wiring harnesses can't be mishandled.  

However, it is far more complicated than that! 

The next generation of vehicles that include self-driving features and electrified powertrains will be borrowing a page from the commercial aviation industry and have redundancy built into their electrical architectures. 

This ensures that safety critical systems will continue to work if there is a power interruption or some other failure. So, just put two of everything in the car, right? But, again, this is complex. 

"We are spending a lot of time right now with the OEMs developing what those strategies are," De Vos says. "Simply duplicating everything is really expensive, especially if you have to duplicate it in different ways. It's like two different development efforts. But fundamentally that's what we have to look at: How do you provide redundancy and fail-operational capability?" 

Gustanski said redundancy is more than just two sets of wires and components. It's onboard computers that can sense when there is a failure in one computer and then automatically provide backup. 

"For safety critical systems, we don't want to leave the driver stranded," he said. "We [have to] make sure there is a way to get you where you need to be, maybe in limp-home mode. So, in the vehicle's electrical architecture we [might] go to centralized computing, one for safety and one for the electrical architecture because they end up backing each other up."

Delphi and other companies are tackling the obstacles of weight and cost – the two major problems with adding redundancy. 

For example, on the second-generation Chevrolet Volt and the latest Toyota Prius, General Motors and Toyota engineers eliminated most of the heavy copper cables by installing the cars' power electronics directly on the transmission, where the electric motors are kept. 

According to Gustanski, Delphi is working in a new generation of lightweight aluminium wires that may also reduce cost. She said that aluminium wire, combined with a thin-wall insulation, may reduce weight by as much as 40% versus copper. 

We have faith in Delphi and its competitors and engineers at Ford, GM, Toyota, Daimler, BMW and others that they will solve these problems and make electrified, self-driving vehicles reliable.

But at what cost?