Improving Cold-Start in Batteryless And Energy Harvesting Systems
As the internet-of-things (IoT) continues to grow, gathering information in a long-term, distributed fashion has required low-power, battery-based sensing systems. In recent years, batteryless sensing systems have received attention from the research community. As opposed to battery-based systems, these harvesting-based systems are very cost-effective and environmentally-friendly because they only use small, typically ceramic capacitors.
In batteryless sensing systems, the smaller the energy storage capacity, the faster the system will be able to recover from 0 V. Boost converters with maximum power-point tracking (MPPT) are able to harvest energy with a high conversion efficiency (>90%), even under dynamic environmental conditions. However, these boost converters typically require a high voltage (>1.2 V) for operation. Before this voltage is reached, the conversion efficiency is typically very low (<10%). Depending on the application-specific capacitance, a minimum amount of energy needs to be harvested before the system can do useful work. A specially designed cold-start circuit can significantly increase the conversion efficiency and reduce both the time and energy to turn on the main boost converter. To demonstrate the impact of the cold-start circuit, the student will implement a photo-voltaic-driven, sense-and-transmit application using a LoRa radio.
In this project, the student will investigate and design a new cold-start circuit that aims to reduce the system’s start-up time. Depending on the chosen architecture, the choice of MPPT algorithm and down converters will need to be justified. A working prototype of a sensor node using LoRa will be developed. Depending on the transmission settings, different energy storage capacities can be evaluated. A thorough experimental evaluation will be necessary, quantifying the start-up time and energy improvement under static environmental conditions.
This project will be developed in close collaboration with MiroMico AG (Zurich) (https://miromico.ch/)
Depending on the applicant's profile and project type, his tasks may involve some of the following:
(not all need to be met by the single candidate)
- Experience using the laboratory instrumentation - signal generators, oscilloscopes, DAQ cards, Matlab etc..
- knowledge of microcontroller programming and PC programming (C/C++, preferably embedded C)
- basic knowledge or interests on power converters, wireless communication, and circuit design at a components level (IC design is NOT involved)
- Motivation to build and test a real system
- PCB Desing or willing to learn it
Detailed Task Description A detailed task description will be worked out right before the project, taking the student's interests and capabilities into account.
- Looking for Semester and Master Project Students
- Supervisors: Michele Magno and Andrez Gomez (from MiroMico).
- 35% Theory
- 45% Implementation
- 20% Testing