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Cars with 48-volt electric systems can use high-power devices
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A 48-volt electric system enables engineers to design high-speed active control equipment for steering, suspension and active safety devices.
PHOTO: AUDI
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What is the advantage of 48-volt electric systems? Why is it necessary and will it not mean more batteries and higher energy consumption?
The conventional automotive electric system operates on a 12-volt direct current (DC) set-up as it has been doing for decades. To date, the 12-volt network is still in use in every passenger vehicle, including electric vehicles (EVs), to power devices such as the lights, infotainment, windows and even the on-board electronic controllers.
Auto manufacturers introduced the 48-volt system because a higher voltage supply enables the use of high-power devices to drive electric pumps, compressors and actuators. The voltage is not supplied by four 12-volt batteries, but from the high-voltage batteries integrated in vehicles with some form of electrification, like hybrids or EVs.
The hybrid or EV battery may be a 120-, 400- or even 800-volt system. A converter is used to bring it down to 48 volts.
A higher voltage means the physical size of electrical wiring and motors can be reduced. For example, a 240-watt motor in a 12-volt network requires 20 amps of current, but only 5 amps – or 75 per cent less – on a 48-volt system. A lower current requires thinner electrical cables.
On the other hand, when higher current components are used, the device will have more power to perform functions that could not have been implemented on a conventional 12-volt vehicle.
With motors and actuators that produce more power and torque, engineers can design high-speed active control equipment for steering, suspension and active safety devices.
One of the earliest uses of the 48-volt system was for active roll control motors, where high torque is necessary to resist the anti-roll bar’s twist for increased roll stiffness.
The 48-volt electrics are now used on hydro-pneumatic suspensions on a number of performance and luxury cars. These sophisticated chassis systems require high-speed pneumatic and hydraulic pumps, valve actuators and steering control motors.
In all such applications, the 48-volt power supply comes from on-board rechargeable batteries, commonly used in the automotive industry for hybrid or fully electric vehicles.
