Column: Electric Vehicles
to transfer the energy load from a mechanical source, which is on all the time, to an electrical source of energy that cycles on and off, allowing better efficiency and control. Te NBM in conjunction with the SAC replicates the essential properties of a physical battery; see Figure 2. With this modular approach, the power
source can be split into zones, with an NBM placed anywhere around the car – behind the dashboard, in the trunk or by each wheel. Having the power source closer to the load reduces parasitic inductances and series resistances, for a higher-performing power system. The same approach also applies to HV-to- 48V conversion, creating a 48V virtual battery; see Figure 3. The largest source of energy in the
vehicle is the traction motor battery, so it makes sense to use that to down-convert voltages. In an EV this is typically either 400V or 800V, soon to be replaced with 1,200VDC or 1,400VDC.
Figure 3: A decentralised architecture offers greater design flexibility and reduced cable and harnessing weight in the vehicle, freeing up space and extending driving range
Figure 2: Vicor power modules bundled with EMI filtering, minimal components and an enclosure could replace a 12V lead-acid or lithium-ion battery, reducing overall system weight by 15-40lbs
To date, “progress” has meant adding more and higher-
powered batteries to cars, but it is time for a fresh look
A modular approach can easily process 700,000A/s, and can be paralleled in an array to create a large power-processing system, with isolation from any primary bus voltages of 60V or higher. In theory, the NBM’s power
capability only suffers due to thermal effects; but, if properly cooled, it can process very large amounts of power, providing the added benefit of bidirectional operation.
www.electronicsworld.com October 2022 15
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