A DC-DC converter is a device that temporarily stores electrical energy and aims to convert direct current (DC) from one voltage level to another.

In automotive applications, they are indispensable intermediaries between systems with different voltage levels of the whole vehicle.

Control circuits play the role of DC-DC converter in the traditional 12V electrical architecture, which has dominated the automotive industry since the 1950s. For decades, new functions and innovations have increased the complexity of automotive electrical / electronic architecture, including cruise control introduced in the 1950s, emission control functions in the 1970s and electrical centers in the 1990s.

DC-DC converters achieve this growth by reducing the power of 12V batteries to lower voltage electrical systems such as instrument panels, entertainment systems, LED lighting and sensors (only 3.3V).

These low-voltage DC-DC converters are still an important part of the control circuits of all automobiles today, whether they are internal combustion engine vehicles or purely electric vehicles.

Purely electric vehicles introduce much higher levels of electricity and require more powerful DC-DC converters.

Systems higher than 60V are considered high voltage; the battery range of a typical pure electric vehicle is 400V to 800V.

For example, the voltage for air conditioning must be reduced to 48V, and the voltage for many electronic devices throughout the vehicle must be reduced to 12V or less.

The voltage may also have to be increased, for example, if a 400-volt battery is connected to an 800-volt charging station.

The expansion of software capabilities, including active security, connectivity, and infotainment, will increase the complexity of the low-voltage architecture.

A purely electric vehicle must provide enough power to drive the car’s wheels while reducing the current to run all the low-voltage equipment that makes up the software-defined vehicle.

They need to be reliable enough to meet the functional safety requirements of autopilot and advanced driver assistance systems.

High-voltage DC-DC converters are larger and heavier than low-voltage converters because additional shielding is required to protect nearby components from electromagnetic interference caused by increased current.

Because electric vehicle designers want to reduce the size and weight as much as possible to extend the mileage of the car, they turn to DC-DC converters with higher power density, in kilowatts per unit volume.

The challenge is to optimize the space while maintaining the highest possible security and efficiency.

Although some automakers retain 12V batteries in addition to the main 400V or 800V batteries, emerging designs achieve higher efficiency by combining larger batteries with more complex DC-DC converters, eliminating the weight, cost, and maintenance of individual 12V batteries.

The software that runs the DC-DC converter is the key to ensuring that the conversion remains efficient, and an understanding of the entire vehicle architecture provides information for software and hardware design.