­High Density Modules Power New Automotive Architectures

Weight matters in electric vehicles. Every extra kilogram reduces the potential range of the vehicle. It also causes other problems, like degrading tires quicker and damaging roads. EVs are already much heavier than their ICE counterparts, making this problem worse. There are a number of initiatives currently ongoing within the automotive world that are intended to reduce that weight. One of those is to move from a distributed architecture to a zonal one. The number of ECUs in a vehicle has expanded dramatically over the last decade or so, and as each of those ECUs has to have the ability to communicate with many more. To achieve this a lot of heavy wiring is required.

Another initiative in the pipeline will see the main power buses in the vehicle migrate from 12V to 48V. The higher voltage will allow lower currents, which require thinner wires. Of course, these changes will require different systems to the ones that we have now, and in the automotive industry, things change very slowly. Vehicle manufacturers are happy with the performance of many of their 12V systems and are reluctant to change until qualified alternatives are available at the right price. The 48V bus will also enable new applications, such as active suspension, that would have been difficult to implement with a 12V supply.

Vicor has talked for some time about how its technology could help automakers with the transition, and has now announced its first range of automotive qualified modules that will allow theory to be put into practice. The company has launched three modules that are AEC-Q100 certified and have completed the PPAP process with customers - BCM6135, DCM3735 and PRM3735

The BCM6135 is a 98% efficient 2.5kW BCM bus converter that has been designed to convert the 800V from the traction battery to a 48V power supply for the vehicle. To keep the overall solution more compact, the device includes the isolation required between the high and low voltage domains. Its 8.0MA/s response rate will also allow designers to use it as a virtual 48V battery, reducing the overall vehicle weight by around 25lbs according to the company. The BCM6135 has a power density of 158kW/L, delivering further weight savings.

The second of the new solutions is the DCM3735 2.0kW DCM DC-DC converter, which transforms an unregulated 48V input into a regulated 12V output. The module is intended to power legacy 12V systems in the vehicle until newer 48V solutions are viable. The DCM3735 has a power density of 300kW/L and a wide input range that can be trimmed within a range of 8 – 16V.

Finally, the PRM3735 is a 2.5kW PRM regulator for 48V power that is 99.2% efficient. Its small footprint and 260kW/L power density frees up packaging space and reduces the size of the overall DC-DC power supply. It is best suited to support the regulated 48V loads that will be implemented in new vehicle architectures.

The company sees the modules as the backbone of any new power architecture. The three devices are designed to work together, or they can be used independently. For example, the BCM6135 can be used to provide a 48V input to the PRM3735 for regulation for the 48V applications in the vehicle, while also supplying the DCM3735 to power regular 12V systems. The devices are all designed to be bi-directional, which is essential for applications such as regenerative braking. If higher power is required, the devices can easily be arrayed, and power sharing is automated between them.

Greg Green, Director of Automotive Marketing at Vicor expanded on the flexibility of the modules by saying, “These three parts are designed to take the battery power and take it down to a safe and useful voltage. What is unique about them is that they are designed to be scalable and flexible. We can put up to 10 BCMs in parallel for power levels up to 25kW. The DCM and the PRM modules can parallel up to five modules each. They can also be arrange serially if individual 12V or 48V circuits are needed. When you take all three of these modules, and look at the different ways that they can be arranged, there are over 300 configurations from 2.5kW up to 20kW of power, and a variety of ways to handle that power. Any power requirement for a vehicle can be created with a combination of these three modules.”