Vicor has developed three automotive-grade power modules that can be used in 300 combinations in 48 V EV systems, writes Nick Flaherty.

They cover a bus converter from 800 V to 48 V, an unregulated 48 V to 12 V converter and a regulated 48 V power-supply module.

The modules allow 800 V from the EV battery pack to a 48 V bus, which can then be converted to a regulated 48 V with another module, or to 12 V for legacy systems with the third module.

“EVs have a weight problem. The weight cuts range; increases wear on tyres, safety and the design of parking structures. Designers can take this technology and implement a number of features to reduce weight by 25 kg and cost by $100,” said Greg Green, director of automotive product marketing at Vicor.

Using 48 V direct from the battery pack reduces the weight of the wiring harness and this avoids the need for a separate, legacy, 12 V power bus by using the third module to provide 12 V of power if required.

The module is bidirectional, so it can be used with active suspension systems to handle the high slew rate of a regenerative power load, which requires immediate current-flow reversal to pass regenerated power back to the battery.

“These active suspension systems are something automakers want to have, but these are power hogs. You can’t do active suspension in 12 V systems as they take too much power, so some designers are using 400 V actuators, but 48 V allows reasonably small actuators throughout the vehicle,” said Green.

“While the average power is 400-800 W, it will peak at 4 kW in microseconds, and this is where the slew rate is exactly what they needed. The module goes from requiring 4 kW to producing 4 kW, and that bi-directional feature is an attractive component.”

The modules use planar transformers, zero voltage switching (VZS) and zero current switching (ZCS).

The BCM6135 is a 98%-efficient, 2.5 kW BCM bus converter, which converts 800 V from the traction battery to 48 V to give a safe, extra-low voltage (SELV) power supply to the vehicle. The converter internally provides isolation between high and low voltage, which creates a large reduction in the space required for the DC-DC conversion.

A power density of 158 kW/L allows for a smaller primary DC-DC converter and reduces vehicle weight. The bidirectional, rapid current, transient response rate of 8 MA/s allows the BCM6135 to replace a 25 lb 48 V battery.

The PRM3735 module is a 2.5 kW PRM regulator for 48 V power that is 99.2% efficient. Its small footprint and 260 kW/L power density free up enough packaging space to supply a regulated, 48 V load.

The third module, the DCM3735, is a 2 kW DC-DC converter, which takes an unregulated, 48 V input and provides a regulated, 12 V output. The module has a wide input range that is compatible with a variety of automotive applications because the output can be trimmed within a range of 8-16 V.