Application of Direct Current (DC) Distribution (REF:C-0012)
E&M InnoPortal Trial Project Ref. No.:

Overview

The application of Direct Current (DC) Distribution aims to improve building electricity efficiency by properly regulating different levels of low voltage Direct Current (DC) grids for different types of appliances. This reduces energy loss in power conversion. The application defines the electricity usage of various DC appliances and provides adaptive DC Power Distribution solutions, such as AC-DC converter, DC-DC converter and DC protection. Moreover, an Android-based energy dashboard is deployed to monitor system behaviour, diagnose fault message, track electricity usage and estimate real-time or historical electricity savings.

Problem Addressed

AC power needs to be converted to DC power for use by DC-compatible devices. Converting AC power to DC power results in significant energy waste due to the inefficiencies in the conversion process. The increasing prevalence of DC power sources in buildings presents an opportunity to mitigate these conversion losses.  However, the common practice is to convert DC power back to AC before running through a building's electrical system, only to be converted back to DC again. This trend opens the opportunity to the deployment of the DC power supply system instead of AC to promote the application of DC by installing DC power equipment. This approach aims to enhance energy efficiency, promote flexible and simple configurations, reduce installation costs and improve reliability.
Innovation

The system consists of an AC Miniature Circuit Breaker (MCB) box to protect AC inlet from any failure of the DC distribution box, a DC distribution box with power converters to covert 220V/50Hz AC incoming voltage into 375V DC voltage for DC appliances, a DC MCB box to safeguard the DC distribution box from appliance failures such as short circuit and a Human Machine Interface (HMI) monitoring system to show DC distribution box status and electricity usage.

Sensors installed on the target machine collect related data periodically, which are transmitted to the Android App in the Android Tablet attached for display and permanent storage. Users can also request real-time and historical data from the Android App in their smartphones through the Intranet of a private Wi-Fi network.
Key Benefits
  • The deployment of a new and efficient AC/DC power converter with five-level topology allows for an even distribution of heat across the semiconductors, enabling high power conversion efficiency and the use of a low-power and quiet cooling fan
  • The new solid-state DC circuit breaker is semiconductor-based switch to replace the typical mechanical switch and controlled by high speed digital operation. This results in a reaction time to a short circuit or over-current event that is 100 times faster than the mechanical breaker, significantly reducing short circuit current by more than 10 times according to the test results
Patent and Award
  • International Exhibition of Inventions of Geneva 2021 (Silver Medal)
  • Hong Kong ICT Awards (2021) – Smart Living Award (Smart Home) Sliver award
  • Hong Kong Green Innovations Awards (2021) – Certificate of Merit
Project Reference

Electrical and Mechanical Services Department Headquarters