Patent ID: 8619445

Claim:
A switched capacitor power converter comprising: a first terminal for coupling to a first external circuit at substantially a high voltage; a second terminal for coupling to a second external circuit at substantially a low voltage lower than the high voltage, wherein in operation of the power converter charge passes on a charge transfer path between the first terminal and the second terminal; a plurality of semiconductor switch elements, including a first set of switch elements on the charge transfer path between the first terminal and the second terminal, wherein no switch element in the first set of switch elements is connected in series with either the first terminal or the second terminal to carry substantially all the current passing through said terminal, and wherein each switch element in the first set of switch elements is configured to form a controllable charge transfer path between a corresponding subset of a plurality of capacitors, and a second set of switch elements configured to form electrical connection of at least some of the capacitors to alternating reference voltages, wherein said plurality of switch elements are configured to form said interconnections in successive states in operation; measurement circuitry configured to measure a voltage and/or a current characteristic of one or more switch elements of the first set of switch elements or the second set of switch elements; and fault control circuitry coupled to the measurement circuitry configured to alter operation of the power converter upon detection of a condition determined when the measured characteristics of the switch elements deviate from a predetermined range of said characteristics.