.... Introduction....

High energy efficiency is a must!

Consuming more energy than an end user actually needs is not only an unnecessary cost and a source of unnecessary pollution, but also has political implications that ultimately lead to energy wars. We must therefore limit energy purchases from abroad as much as possible and exploit renewable energy sources available locally as much as possible.

Technically, we have other options for saving a few percentage points of energy by adopting direct current (DC) electricity distribution in factories.

.... In summary.... 

- Instead of the traditional 400 VAC, 50 Hz power distribution in Europe and other countries, DC power distribution could be used, with only two cables instead of three cables for power sharing.

- Machine manufacturers will no longer have to deal with markets with frequencies of 50 Hz or 60 Hz at different voltages and with different transmissions ratios; a single power supply will provide the correct DC voltage required by the machinery, which will therefore be of a single, standardized type worldwide.

- The energy efficiency of the system (distribution network plus machinery) will improve by several percentage points.

- The cost of power electronics on the machinery will be reduced gradually, as the various distributed current rectifiers will no longer be necessary.

- The cost of power wiring in the factory and its installation will be reduced, as there will be fewer cables to install and a shorter overall length.

- With the same existing electric motors controlled by inverters, a power increase of up to 20% can be achieved, while reducing size, weight, and price, thanks to the increased available DC voltage.

- The vast majority of various power quality issues will be solved at the root, and it will be much easier to add small energy storage devices (capacitors, supercapacitors, or batteries) where useful, or large storage devices to power the factory for several days in the event of a total power outage.

- In new constructions with new machinery, or in complete renovations of some departments with machinery upgrades, DC power supply is advantageous both in terms of purchase price and lower energy costs.

- It will be easier to connect renewable sources to the system, even of different types and power ratings, even at a later date. Photovoltaic panels will supply energy to the factory without the need for inverters.

Many major companies around the world are working on this major project, which requires standardizing voltages and protection systems to ensure the necessary interchangeability of components.  

It has been demonstrated that eliminating unnecessary converters not only leads to greater energy efficiency, but also to a reduction in space and costs, as well as increased reliability, as fewer components are subject to potential failure.

This comparison clearly shows the potential savings achieved by adopting the DC philosophy:

(Image linked from "Power Electronics News") 

Currently, only a few companies are able to convert their internal factory networks to operate exclusively with DC; it will be several years before all the necessary components can be easily found at competitive prices. For example, super-fast fuses for high DC currents at the required voltages already exist, but they are not currently manufactured in industrial-grade containers (these are fuses with a small explosive charge inside, similar to airbags).

Nearly all of the world's leading electrical engineering and power electronics companies are holding working groups to determine standardized voltage levels and protection specifications, which will need to be interchangeable with competing products. Some cable manufacturers already have cables designed for DC distribution in their catalogs, which requires design solutions to ensure long cable life, as the DC voltage always has the same polarity and is therefore subject to phenomena not seen in AC cables. There will also be savings on cables, both in terms of cable cost, given their shorter overall length, and lower installation costs.

This innovation will necessarily lead to greater interchangeability between equipment from different manufacturers, which will all operate fairly similarly, at least for general applications. Since current 50 Hz motors will be able to deliver approximately 20% more power, and since the price of simplified inverters for DC-only power will be increasingly affordable and their reliability will be much higher than current ones, and considering that inverters are sized for current, so increasing from 50 to 60 Hz does not increase their size or price, the vast majority of three-phase motors will be equipped with inverters, with advantages in terms of performance and energy efficiency. In electric vehicles, some inverters have achieved performance levels unimaginable just a few years ago; for example, an inverter for a 300 kW motor is the size of a shoebox. All things considered, for the vast majority of motors used in industry, inverters will be very small, barely larger than current terminal boxes, and will therefore almost always be mounted directly on the motors, except for special high-temperature applications or those with specific requirements.

I suggest to companies in the electrical and electronics sector begin evaluating this substantial change before it's too late. There are already examples of DC solutions specially in the naval sector.

(Mario Maggi, https://it.linkedin.com/in/mariomaggi )

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Can a DC voltage be transformed into another voltage, as with an AC transformer?

• Isolation between the high and low voltages must be ensured, or an "autotransformer" must be used where isolation is not required.
• If the low-voltage side is powered, high-voltage energy must be transferred to the other winding.
• If the high-voltage side is powered, low-voltage energy must be transferred to the other winding.
• The efficiency level must be high.
• Reliability must be high.
• It must be able to function correctly under different load levels, including no-load conditions.

The "DC transformer" exists and is an industrial product from the Spanish company Epic Power, offered by AXU Snc in Italy: https://www.axu.it/ep/

The well-known Japanese multinational Yaskawa Electric - which never advertises other people's electronic products - publishes a special application on its website citing the name of the electronics manufacturer Epic Power: https://www.yaskawa.eu.com/battery-testing-outside-the-laboratory-the-system-sustainable-industry-needs_u14273 , a sign that we are dealing with a truly interesting DC/DC converter.

Normally the "direct current transformer" which is a bidirectional DC/DC converter, is offered in this form, ready for installation in an electrical panel or in a machine:

Many modules can be paralleled to achieve power outputs greater than one megawatt in a 19" rack cabinet:

Initiatives around the world and information from major companies

Current/OS Foundation

Commissione Europea

ODCA

DC Systems

EMerge Alliance

Irena - Renewable MiniGrids

Normativa VDE SPEC 90037 V1.0 in inglese

Microgriglie in DC da Weidmueller

Roadmap DKE della standardizzazione in Germania

Conversione da AC in DC per microgrid a corrente continua - Schneider Electric

Applications DC microgrids

Phoenix Contact

Mercedes AG 

Schaltbau

ABB Onboard DC Grid

DC microgrid nelle marine

Data center di NVIDIA in DC

DC Experience center in Amsterdam by Schneider Electric

Nexans

Articles

IEEE Xplorer: Renewable Power Routing from a DC Microgrid to an Industrial Cluster

IEEE Xplorer: Multi-criteria Methodology for the Sustainable Powering of an Industrial DC Microgrid Cluster

Data Center Frontier: https://www.datacenterfrontier.com/sponsored/article/55308211/high-voltage-dc-power-the-future-of-data-center-power-architecture

Blog Mouser Electronic: Resources for DC Microgrid

Magazine "Fare Elettronica": DC Microgrid: il prossimo passo nell’evoluzione energetica

Architecture NVIDIA: Architectural Imperative of 800 VDC and Integrated Energy Storage

Diagrams data center NVIDIA: nvidia-800-v-hvdc-architecture-will-power-the-next-generation-of-ai-factories/

EO Elettronica Oggi - Microgrid in DC: https://elettronica-plus.it/brochure/eo/533/32/#zoom=zC

Italian Magazine "Economy" - 20260501 - Pag.57...59 - Considerazioni su adozione della DC (purchase online)

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MOOC - Free online teaching on DC microgrids

On YouTube, thanks to Current/OS:

1 Introduction

2 Voltages

3 Power management

4 Electrical protections

5 Precharging

6 Earthing

* Solutions offered by STMicroelectronics 

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Basic information is provided to companies free of charge via email. For paid DC network consulting requests, please write to info@axu.it