1:1 Resonant Switched Capacitor with Capacitive-Based Isolation

In power electronics, galvanic isolation is required for safety reasons, and when large DC or AC voltages have to be withstood between the input and output of a power converter. Galvanic isolation in the form of a magnetic transformer prevents failures in one side of the converter to be transferred to the other side and provides voltage transformation. Transformers are used for power applications, but optocouplers or capacitive barriers can be used to transfer control signals. However, the main limitation of transformers is that they are heavy, bulky, and lossy, and, as a result, transformer-less topologies conventionally achieve better performance. In this paper, a topology is proposed where galvanic isolation is obtained through capacitors rated to the maximum common-mode voltage, rather than relying on transformers. First, the fundamental principles of the idea are discussed. The operation of the proposed 1:1 resonant switched capacitor converter is introduced, emphasizing the effects of varying common-mode voltages. Later, zero-voltage switching is covered, and finally, the operation is validated in simulation.