MetrUS Power Analyzer

MetrUS is a bachelor's degree project at the Université de Sherbrooke in Quebec, Canada. The team is composed of 8 final year students in electrical engineering, each one having a dedicated responsibility in hardware, firmware, software or management. The idea of designing a three-phase power analyzer comes from a member during an internship in industrial electricity. This kind of device could be used to have a better understanding of a plant electric grid and to reduce operational costs. As students, this project is a wonderful opportunity to learn about power electronics integration in industrial systems. First of all, it is not common to design with such high voltages (up to 600Vac electric systems) at the university. It is also a great engineering challenge to design safe, reliable and precise circuits while taking account the mechanical integration of the power connectors and the communication I/Os. Finally, we must develop our management skills in order to deliver the prototype in time for the public exhibition called MEGAGéniale (https://www.megageniale.usherbrooke.ca/), it’s a student engineering project exhibition open to public and media to spread final year students realizations.

The power analyzer is made of two printed circuit boards working together. The first one (ZapdUS code name) is the mother board. It contains the analog measurement circuit along with the current inputs. This side of the PCB is galvanically isolated from the other side. The brain for the measurement is a high-performance microcontroller getting data through the isolation and computing values such as RMS voltages, RMS currents and total harmonic distortion with our custom metrology algorithms. In order to add a time tag on data, the MCU integrates a RTC (Real Time Clock) and a calendar that is battery powered to avoid desynchronization during power outages. The exit door to the real world in our product is a dedicated communication processor, which is chosen to be a WiFi module. The module receives packets from the MCU and transfer them through WiFi or Ethernet, depending on the chosen communication mode. Obviously, there are other components such as RAM, nonvolatile memory, DC-DC converters, isolators, LEDs and connectors. The design uses a 6 layers PCB with controlled impedance for high speed signals, which is achieved with a PCBWay predefined stackup.

The second PCB is the one receiving the high voltage input. It includes an isolated AC-DC converter, over-voltage protections and voltage signal conditioning for the measurement circuit.

To minimize the risk of late hardware final integration, we designed at an early stage prototypes to validate the design of the communication module and the AC-DC converter. That gave us the chance to optimize these important circuits for the final prototype.  Here are some pictures of these prototypes.

MetrUS would like to thank PCBWay for their sponsorship in this complex project. Only being students in this rather expensive field of electronic (high voltage components and high-speed design) is quite challenging on the financial side and the help is highly appreciated.