Using the DCM in a Power Chain for a Small Electric Car

March 17, 2015

Hybrid and fully electric vehicles need power components to convert the high voltage from the battery bank to lower voltages required for equipment in the cabin, as well as to reverse the conversion for battery charging.

electric vehicle whiteboard imageIn this Whiteboard of the Week application developed by Johnny Yuen, senior applications engineer at Vicor, a VI Chip DCM converter module is used to provide the lower voltage. In this interview Johnny explains why the DCM was such a good choice for the application.


What was the requirement you needed to meet with your power chain?

The application was a low-speed, small electric car, with a 350Vdc battery bank (262V-383Vdc range). The customer needed to convert the high voltage to 13.8 V DC, with an output power of up to 600 W to supply the 12Vin peripheral loads such as lighting, audio, display, etc. The power chain also needed to charge a 12V lead-acid battery.


What were the key criteria for the power chain?

As with most electric vehicle (EV) applications, weight was the primary concern. As the vehicle was small, space was also limited.

Of course efficiency is always a key requirement in these applications, not only to optimize the use of energy from the battery, but also to reduce the power dissipated as heat, which in turn means that a smaller and lighter heatsink is required.


Why did you pick the VI Chip DCM Converter Module for this application?

Using the DCM for this application not only produced a very simple power chain, it also provided several important technical benefits. The ChiP package is very compact, while the high switching frequency Double-Clamp Zero-Voltage Switching (DC ZVS) and very clever Adaptive Cell topology ensured efficiency, flexibility and low electrical noise. The DCM also uses a leading-edge planar transformer design that enables a symmetrical PCB layout. This means that the EMI/EMC design is easier, and the resultant circuitry requires less space.

The ChiP package offers very efficient cooling, allowing heat transfer on the top and bottom of the package, as well as through the module pins. It is also very rugged: it has been certified to MIL-STD shock and vibration tests, making it an ideal solution to deliver high reliability in a mechanical vibration-rich environment such as in an automobile.


Are there any other considerations that engineers need to make when designing with the DCM?

Designing with the DCM is easy. Perhaps the only thing that customers need to be careful about is correctly sizing the input and output capacitors, ensuring that the minimum and maximum capacitance on input and output are observed. This, however, is simply a matter of checking the data sheet.


To view this power chain for an electric vehicle, click here.

2 Responses to:
Using the DCM in a Power Chain for a Small Electric Car

  1. Omer ATLI on April 9, 2015 at 10:30 AM

    DCM seems a big step towards the robustness of the EVs. However I couldn’t find any design tips related with DCM based on water cooling. Appreciated to hearing recommendations and/or practical experience regarding to water cooling if it’s a must.

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