Technical Article

How DC-DC Converters are Making Inroads Into Vehicles and Transport Systems

August 18, 2019 by Frank Vondenhoff

This article highlights Bel Power Solutions DC/DC technology with 50/700 DNC40-12/24-8G (liquid-cooled) and 350/700 DNC40-12/24-CG (convection-cooled).

Automotive manufacturers are now seriously considering moving away from the traditional rotating alternator and migrating to DC/DC converters for road transport applications. Thanks to the efficiency, reliability, compactness and practicability of modern DC/DC converters based on the latest semiconductor technology, DC/DC converters can now displace alternators for powering auxiliary components and battery charging.

To meet this growing demand, power solution companies are now offering a line of products in a wide variety of standard configurations, with custom modifications also available.


Development of eMobility family for road and air transport systems

To serve this emerging market, Bel Power Solutions has developed the eMobility family, which targets the electrification needs of road and air transport systems. The product family is focused on the development and improvement of EV power components and, like other Bel initiatives, the eMobility products are developed globally, at design centers in Slovakia, Switzerland, China and the US. The product family is able to address the emerging needs of electric and hybrid electric vehicles of all sizes and power requirements.

Globally, there is a strong focus on replacing buses and trucks with EV alternatives, as well as all types of passenger vehicles, from sports cars to people carriers. DC/DC converters can now meet the needs of all road-going, off-road and workplace transportation, including ground-support and construction vehicles. Even rollercoaster operators are switching on to DC/DC converters.


Figure 1: The Bel Power Solutions 350DNC40 is a 4 kW DC/DC Converter that creates DC voltages in hybrid and electric vehicles suitable to power low voltage accessories.
Figure 1: The Bel Power Solutions 350DNC40 is a 4 kW DC/DC Converter that creates DC voltages in hybrid and electric vehicles suitable to power low voltage accessories. Features include very high efficiency, high reliability, low output voltage noise and excellent dynamic response to load/input changes.


The convincing advantages

When discussing the advantages of DC/DC converters in contrast to traditional rotating alternators, it is apparent that they are powered directly from high-voltage battery packs instead of a generator that is mechanically coupled to the engine. The advantage here is higher efficiency; there are no moving parts, such as belts and pulleys that can also represent a point of failure. DC/DC converters are also much reliable and efficient in the regulation of their output voltage.

To support this emerging trend, Bel has committed to the design, specification and support of DC/DC converters that can maximize business value. By leveraging the latest advances in CAN bus communication and other technologies, they deliver high performance with the option for customization for specific applications. Prices are competitive, lead times are short and are offered with excellent customer service and technical advice.

Examples of Bel’s DC/DC technology includes the 350/700 DNC40-12/24-8G (liquid-cooled) and the 350/700 DNC40-12/24-CG (convection-cooled) ranges of down-converters that deliver up to 4kW of power with liquid cooling, or 3.3kW with convection cooling. There are models available in these series that can handle input voltages from 240 to 850 VDC. With high efficiency of typically up to 93%, the products in these ranges deliver robust and highly dependable performance with low output voltage noise, and excellent dynamic response to changes in load or input.

The output voltage is nominally either 14.4 or 28V but can be adjusted over the CAN bus serial interface. Input and output are fully, galvanically, isolated. Communication and control are optimized via CAN bus according to SAE J1939.

As mentioned, cooling can be achieved either by liquid or convection. The operating temperature of liquid-cooled models ranges between -40° and +85°C, while convection-cooled models offer -40° to +45°C. Each converter in the 350/700 DNC40-12/24 Series is equipped with over-temperature, output overvoltage and overcurrent protection. Each model is also protected with regard to input and output polarity. Ingress protection is rated at IP65 and IP67, and E-mark compliance is also included (Table 1).


Model Power (W) Output voltage (V) Output current (A) Voltage in-put (VDC) Operating temp (°C) Protection Cooling type Dimensions L x W x H (mm)
350DNC40-12-8G 4000 14.4 278 240-430 -40 to 85 IP65 and IP67 Liquid 270 x 113 x 341.5
350DNC40-24-8G 4000 28 143 240-430 -40 to 85 IP65 and IP67 Liquid 270 x 113 x 341.5
350DNC40-12-CG 3300 14.4 229 240-430 -40 to 45 IP65 and IP67 Convection 350 x 187 x 341.5
350DNC40-24-CG 3300 28 120 240-430 -40 to 45 IP65 and IP67 Convection 350 x 187 x 341.5
700DNC40-12-8G 4000 14.4 278 400-800 -40 to 85 IP65 and IP67 Liquid 270 x 113.3 x 343
700DNC40-24-8G 4000 28 143 400-800 -40 to 85 IP65 and IP67 Liquid 270 x 113.3 x 343
700DNC40-12-CG 3300 14.4 229 400-800 -40 to 45 IP65 and IP67 Convection 350 x 187.7 x 343
700DNC40-24-CG 3300 28 120 400-800 -40 to 45 IP65 and IP67 Convection 350 x 187.7 x 343
Table 1: Product specifications of the BEL 350/700 DNC40-12/24 Series.


Customization is a key feature

Customization of DC/DC converters for automotive applications is regarded by Bel as a necessary extension of its standard product specifications. This is especially true in the automotive field, where it is commonplace for manufacturers to present different requirements. The Bel eMobility family is able to accommodate almost any requirement including, for example, meeting precise output voltages.

A recent example of this can be seen in Zurich Airport, Switzerland. The auxiliary power supply for airplanes being serviced at the gate, which is usually a diesel generator on a ground support vehicle, has been replaced by a 300VDC battery pack and DC/DC converter. This delivers a much cleaner and more convenient charging procedure. Bel has also provided DC/DC converters for other unusual applications, such as a rollercoaster entertainment park that required power to be reliably maintained at all times to the ride’s 20 carts.


DC/DC converters and electrification trends

The electrification of transportation systems continues and is creating substantial demand for advanced DC/DC converter solutions. Drivers include the growing interest consumers have in sustainability, matched by the business requirement for cost-effectiveness, while legislators continue to implement limits on emissions to help protect the environment.

The EU is leading the way in this regard with new regulations that force European cities and metropolitan regions to limit access to diesel-powered buses and outdated petrol-fueled vehicles, in favor of cleaner electric alternatives. It is possible that by 2025 many European cities will only allow electric buses on their inner-city roads.

These trends are being adopted by the wider logistics industry, not least because of the emission and congestion charges that continue to be applied. This is an industry focused on efficiency in all its forms, and it is becoming more convinced about the positive cost potential and public image that can come by adopting a clean energy policy.

Another active area for Bel and its eMobility products is the off-road vehicle sector, particularly those used by the military, mining and construction industries. One vertical market that remains virtually untapped is marine transport, which includes public ferry services and pleasure boats. In Amsterdam, the Netherlands, there are expectations that all boats using its canals will be electrified within the next few years.


Change is getting underway

The technology behind electric transportation systems, for pleasure or industrial use, is maturing to become a major market presence, and it would be difficult to argue against electric powered vehicles representing the future of transportation.

Bel Power Solutions is well positioned to support this transition to the electrification of road, air and sea transportation systems. Bel offers advanced technology and knowledge in this area and is equipped to assist its customers with the development and supply of efficient and reliable DC/DC converter technology, including custom product specifications, to enable a perfect fit for any application.


About the Author

Fran Vondenhoff is a Business Development Manager at Bel Power Solutions, particularly Business Development Manager Power Conversion at Bel Power Solutions (Power-One) – A Member of the BelFuse Group Amsterdam Area, Netherlands.


This article originally appeared in the Bodo’s Power Systems magazine.