Concepts for integrated capacitive voltage converters with high input voltage

• Applicant: Professor Dr.-Ing. Bernhard Wicht
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 491790667

The overall goal is to explore capacitive voltage converters (also referred to as switched-capacitor or SC converters) for higher voltages >100V and moderate output power in the range of several hundred milliwatts. The results of the research will be demonstrated experimentally in a converter system consisting of a high-voltage microchip and compact external components. This has not yet been achieved in the state of the art. The planned research thus addresses an area for which no solutions have been published. Application areas may include sensor supply in cars and buildings, highly integrated power supply for IoT and USB chargers. The sub-goals include work at architecture and circuit level. The first step is to develop suitable converter architectures and to identify adequate high-voltage semiconductor technologies. Exploring and narrowing the parameter space for SC converters will require modeling the area requirements of capacitors and switches and the relevant loss mechanisms. Approaches to be evaluated on the architecture side include multi-ratio converters and an extension towards resonant concepts (by combining them with a typically very small inductor). Based on the pre-work for this research project, a multi-phase approach will be specifically investigated. By adding additional phases per switching period, more charge is exchanged between the capacitors and transferred to the output. This makes it possible to achieve higher conversion ratios with a smaller number of capacitors than in 2-phase operation. As the voltage increases, so do the requirements for implementing circuits. Therefore, high-voltage circuits for control and regulation of the identified architectures are to be developed. A sub-goal is dedicated to the question of whether it is possible to develop a generally applicable and highly efficient solution for the generation of the flying gate drive voltage at the integrated power switches. To date, there are only insufficient solutions on this topic in the state of the art. After the architectures and circuits have been developed, variants of integrated voltage converters are implemented as microchips, manufactured, built-up as a system and evaluated experimentally. In addition to the overall functionality, parameters such as efficiency, load characteristics, common-mode transient immunity (CMTI) are examined and, thus, the degree of modeling is also verified.

• DFG Programme: Research Grants