The rise of 48-volt electrical systems

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The rise of 48-volt electrical systems

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Automotive supplier Delphi reckons the impending switch to 48-volt vehicle architectures will come sooner than expected, predicting that as many as 11-million vehicles equipped with higher-voltage systems will be produced worldwide by 2025.

Executives say moving to 48-volts is the most likely path forward as motor manufacturers seek to meet upcoming fuel-economy and emissions requirements around the world, and they say that the company’s higher-volt technology will be fitted to new cars from as early as next year.

According to a statement, commitments have already been received from two automakers to use new system. Though Delphi hasn’t named the brands, earlier this year at the Consumer Electronics Show in Las Vegas, the company displayed a Honda Civic 1,6-litre diesel fitted with the architecture.

The high-voltage battery system, which offers considerably more power than a standard 12-volt system, is expected to be used to enhance the fuel economy of mild hybrid powertrains by taking away the strain of running accessories, such as air conditioning.

Delphi officials believe the system will offer 70% of the fuel-economy benefit of higher-voltage mild-hybrid systems at 30% of the cost.

According to Jeff Owens, executive vice president and chief technical officer at Delphi, 48-volt systems are “becoming an extremely attractive lever we think that OEs will be pulling around the world. It will be a lever we think will be pulled very, very hard.”

Mary Gustanski, the company’s vicepresident for engineering and programme management, says the European market will lead the move to 48-volt systems, driven by new emissions requirements that take effect in 2021.

She expects China, which is dealing with severe smog issues, to be close behind though the United States market – where mandated fuel-economy requirements don’t reach their peak until 2025 – will lag slightly. She adds that the Delphi system is scheduled to go into production from next year, though orders are expected to pick up considerably only from 2020.

Other suppliers – including Continental and Valeo – are also developing 48-volt systems but Gustanski says there is unlikely to be a big difference between what component makers have to offer in the initial development phase. She believes that fuel-economy of vehicles fitted with 48-volt systems will improve by as much as 15% – over and above the 15% that comes from downsizing to a direct-injected petrol engine with turbocharging and variable valve timing.

According to her assessment most – if not all – initial 48-volt systems will be designed around the powertrain, leaving the rest of electrically driven components to continue to operate on 12-volt architecture and conventional lead-acid battery technology.

However, once that dual-voltage system is in place, motor manufacturers can begin moving more and more components to 48-volt systems, with prime targets being high power draw items such as coolant pumps, air-conditioning compressors and adjustable suspensions.

“The base 48-volt systems offered by suppliers will be near identical, with e-chargers – electrically powered turbochargers – and a 10% to 15% gain in fuel economy,” she says. “The next step is where you’ll see differentiation, where we optimise the electrical architecture.”

The future for 48-volt systems is much more near-term in the eyes of Delphi executives than is the fully autonomous car, although the supplier sees strong demand for the technological building blocks ultimately needed for self-driving vehicles over the next few years.

As part of a big green push announced recently, Mercedes-Benz will launch a new family of efficient petrol-fuelled engines next year and will begin rolling out 48- volt systems with it, most likely in its more expensive models.

According to a statement released earlier this year, the company intends to use 48-volt systems to power mild-hybrid functions like energy recuperation (commonly called brake regeneration), engine stop-start and electric boost. These features will be enabled through either an integrated starter-generator or a belt-driven generator (RSG).

Interestingly, Audi already has 48-volt systems in production – the threecompressor engine used in the SQ7 makes use of an electrically powered supercharger that draws 48 volts, and there’s a new SQ5 diesel model on the horizon that will use a similar setup.

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