22 POWER MODULES www.vicorpower.com Issue 2 2025 Power Electronics Europe www.power-mag.com Power modules accelerate the path from 800V to 48V SELV in automotive The BCM6135 DC-DC converter module enables unprecedented EV power design innovation By Patrick Wadden, Global Vice President of the Automotive Business Unit at Vicor Corporation The electrification of automobiles is one of the toughest power challenges of our time. At the heart of these increasingly complex electrical systems is the 800V battery and the power conversion challenges it presents. In parallel, OEMs are moving from 12V distribution network to 48V bus to capitalize on the greater efficiency that results from lower current, more power and a lighter wire harness /cabling. So, there are multiple moving parts and the path to the perfect power delivery network (PDN) is laden with trade-offs. For example there is a robust ecosystem of 12V loads that have been commoditised for automobiles over the decades that are not compatible with 48V. But the benefits of moving to 48V are undeniable. For example, the 12V wiring harness, one of the heaviest subsystems in today’s vehicles, can be reduced dramatically moving to 48V. It is comprised of thousands of copper wires totalling over a mile in length and weighing as much as 150 lbs (68kg). Distributing power at 48V means moving to 10 AWG wiring that is less expensive and up to 85% lighter than a conventional 12V harness. This reduces size, weight, costs and design complexities. It’s an indisputable win with no significant downside. Driving the move to 48V are powerhungry loads, such as active suspension, which has a storied history of overwhelming power engineers. 12V has never been enough to adequately power active suspension, nor many other sizable loads found in today’s vehicles. 48V combined with high-density DC-DC power modules will change the way power engineers view this one-time albatross. 48V is making it easier to power heated windscreen, power-assisted steering and braking, plus a host of pumps, fans and actuators. Together 48V and power modules will help power engineers innovate more than ever. Solving the high-voltage 800V to SELV power challenges Converting from 800V to the SELV— or 48V nominal and below — can be complex. The architecture needs to operate at high efficiency and ensure safe operation with adequate cooling. Rapid transient response times are another important feature for many subsystems, delivering the ability to adapt to rapid changes in load while maintaining stability. This helps to ensure safe operation of loads like braking and steering where any delay can become a serious safety risk. Conventional DC-DC converters can deliver power without the need for an intermediate battery, but the trade-off is that they are bulky and lack the fast response time required to meet the power draw by the wide variety of subsystems that require redundancy. The high-density power module is an alternative to a traditional DC-DC converter that is having a big impact in EV power system design today. Its planar design, specialized magnetics and advanced packaging supports high efficiency, rapid response time and a very small footprint. The Vicor BCM® bus converter technology delivers low path impedance and fast response time, transforming the high voltage battery into something that can simulate a 48V or 12V battery, thus eliminating the need for intermediate energy storage. BCMs provide 98% peak efficiency and are capable of delivering up to 65A (over 3000W) of power continuously. These characteristics can support a broad spectrum of high-power PDNs in a vehicle. BCM DC-DC fixed-ratio converter perfect problem solver for EVs Unlike a conventional converter, which regulates the input voltage range to a specific output voltage, a BCM converter is a fixed-ratio converter where the output voltage is a fixed fraction of the input voltage, known as the ‘K factor’. Operation is in three stages: primary-side switching Figure 1 The Vicor BCM® bus converter technology delivers low path impedance and fast response time, transforming the high voltage battery into a “virtual low voltage battery” that can simulate a 48V or 12V battery, thus eliminating the need for intermediate energy storage. BCMs provide 98% peak efficiency and are capable of delivering up to 65A (over 3000W) of power continuously. These characteristics can support a broad spectrum of high-power PDNs in a vehicle.
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