Column: Electric Vehicles
or lower. From a global perspective of an EV, HEV or PHEV, there is redundancy of series regulator stages. An HV-to-12V DC-DC converter regulates the 12V bus (with an efficiency hit), and the pre-regulator provides the suitable internal rail voltage for each load; see Figure 1. This legacy architecture originated
when vehicles had alternators. A sensitive 12V PDN needed regulation to charge the battery, keep the radio going during cranking events, and maintain incandescent headlights at the right intensity. OEMs were very creative in bypassing the 12V power limitation, designing complex electrical architectures with two 12V batteries, one 24V battery for power steering and several DC-DC converters in between.
A virtual battery A better approach is to completely rethink the vehicle’s PDN: eliminate the physical 12V battery and replace it with a 12V “virtual” one from the primary battery; see Figure 2. Every EV has a main battery, so it doesn’t make sense to carry additional energy storage devices. The ideal vehicle architecture should
have one HV (400 or 800V) battery for the powertrain and all auxiliary loads. Vicor’s high-density BCM bus converter module enables this by virtualising a low-voltage battery (48V or 12V) directly from the HV battery. Utilising zero-voltage, zero-
current switching (ZVS/ZCS), Vicor’s converters operate at higher frequencies than conventional converters, yielding greater responsiveness than a physical battery. For example, the BCM6135 operates at 1.2MHz and, unlike a conventional ZVS/ZCS resonant converter, operates in a narrow-band frequency range; see Figure 3. The BCM’s high-frequency operation provides fast response to changes in load current and a low-impedance input-to-output path. Fixed-ratio conversion, bidirectional operation,
Figure 2: Optimised E/E architecture eliminates the physical 12V battery. A virtual 12V battery is created by transforming the high-voltage battery with Vicor BCM bus converter technology
Figure 3: The fast load transient response of BCM6135 is the key to supporting the 12V loads. The transient response is 8MA/s. Yellow: input voltage (800VDC); red: output voltage (48V); blue: output current
www.electronicsworld.com November 2022 15
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44
