Bosch Powernet Guardian Replaces Fuses

The shift to by-wire systems for crucial automotive controls such as steering and brakes means that the power source for these systems needs to be especially robust. Even an electric-powered assistance system such as electric power steering is sensitive to being knocked offline by a blown fuse.

At an event at the company’s Michigan proving grounds, Bosch demonstrated a metal-oxide-semiconductor field-effect transistor (MOSFET)-based system for regulating power flow that recovers from an overload in just 0.000015 seconds. That compares to a delay of two or three seconds for fuse-based systems.

Powernet Guardian has advanced diagnostics of connected resistive loads and the wiring harness, predicting voltage drop and providing load management capabilities

Rivian demonstrated similar technology in its recent refresh of its R1T and R1S, but Bosch’s Powernet Guardian will be available to other OEMs, unlike Rivian’s in-house system. To demonstrate the importance of a faster switch-over in case of an overload, Bosch provided a Jaguar I-Pace EV to drive through a cone course.

The Bosch Powernet Guardian module, with its redundant power input and output connectors at the bottom. DAN CARNEY

The engineer riding along simulated a problem with the car’s cooling fan by shorting the fuse on that circuit. Doing that also disables the Jaguar’s electric power steering system. Losing the power steering for a few seconds while steering through cones is a surprisingly tough challenge, with much higher-than-expected steering effort.

Related:Bosch Brake Control Pad Replaces the Conventional Brake Pedal

I had the benefit of knowing the problem was coming, but an unexpected power steering failure of that duration would likely cause a crash in any circumstances other than driving in a straight line. The same test using Powernet Guardian showed that the brief loss of power while the system re-routed power from another source is completely imperceptible. Which is how you want your loss of power steering to be.

Dodging cones is harder than expected when the power steering goes out, even when it is only for two or three seconds. BOSCH

It would be even more dramatic if it were a by-wire brake or steering system that failed completely rather than just losing power assistance. Powernet Guardian is Automotive Safety Integrity Level D-capable and is available at what Bosch characterizes as an “attractive system cost.”

The cost was attractive enough to lure at least one OEM customer so far, as a European OEM is on track to deploy Powernet Guardian in production models soon, according to Bosch.