Today's bulky electrical systems soon could be replaced by black boxes with semiconductors if the auto industry moves to a higher-voltage standard.
Automakers are preparing to triple vehicle voltage in order to meet growing power demands from luxury accessories. And stemming the escalation of wiring will mean new approaches to distributing electricity.
But reinventing the vehicle's power grid comes with potentially huge increases in cost and complexity.
The industry's likely alternative: solid-state switching systems that would regulate power for every electrical load in the car. The change would be akin to replacing a home power panel with a small computer.
The auto industry has been slow to adopt new electrical practices. But that may begin to change rapidly. A new industry voltage standard could materialize as early as 2002, when the first European luxury vehicles with 42-volt electrical systems are expected to reach the market.
BLOCKS AND FUSES
The engineering challenge is to ensure that all vehicle hardware has access to enough voltage, but not too much. Many vehicle systems burn out or face declining efficiency unless they can somehow stay on a low-volt power supply. Electronics, light bulbs and ignition coils fall in this category.
Currently, vehicle electrical systems use large plastic 'blocks' of multicolored electromechanical fuses and relays to divvy up and regulate the alternator's power. When a fuse blows, the owner must replace it.
Automakers are considering scrapping those blocks in favor of new electronic modules that can perform several functions now performed by electromechanical components. They include on-off switching, fuse protection with automatic resetting and fault diagnosis.
In such a system, voltage regulation could be done by electronic hardware. One example is 'pulse width modulation.' A computerized switch quickly opens and closes the circuit to motors, coils and other inductive devices. By adjusting the length of the pulse, the switch regulates the effective voltage at the device.
In a high-volt electrical system, such gizmos likely would never need replacing and could customize power delivery enough to handle every vehicle component.
'It's like going to Burger King; you get exactly what you want,' said Michael Matouka, an electrical engineer with General Motors.
DID SOMEBODY SAY COST?
However, not everyone is jumping into the drive-through line just yet. Some automakers may be hot on electronic power distribution, but 'they've been saying that for the past 15 years,' said Chris Jager, a product engineer with Omron Dualtec Automotive Electronics Inc., in Oakville, Ontario.
The higher costs of solid-state components are a roadblock. A 10-amp solid-state relay sells for around $5, Jager said, vs. $2 for a comparable electromechanical relay.
Since today's electromechanical relays have proved reliable through hundreds of thousands of switchings, 'they can't justify it on durability,' he said. 'We manufacture solid-state relays, but they're a real tough sell in the auto industry.'
Wary of the cost of such a road-to-roof electric system overhaul, the industry is gravitating toward near-term solutions that change existing electrical architectures as little as possible, say suppliers.
'The objective is to accommodate (triple voltage) within the existing architecture,' said Joe Fadool, marketing manager for body electronics at Siemens Automotive in Auburn Hills, Mich.
Siemens' Smart Junction is designed to do that by replacing the electrical system's 'middle management' of fuses and relays with computerized controls for on-off switching, fusing and the multiplexed signal control that oversees the devices.
To hold down cost, traditional electromechanical fuses and relays are used where possible.