Capacitor balancing circuit and control method for an electronic device such as a multilevel power inverter

摘要

A method of balancing voltages in a group of capacitors of a power electronic device, such as a multilevel power inverter, includes making a balancing determination regarding whether to (i) inject energy into the selected one of the capacitors from an energy storage element, or (ii) extract energy from the selected one of the capacitors into the energy storage element based on the voltage of a selected one of the capacitors, and either injecting energy into the selected one of the capacitors from the energy storage element, or extracting energy from the selected one of the capacitors into the energy storage element based on the balancing determination. Also, a voltage balancing circuit that implements the method. In one particular implementation, a spatial second derivative algorithm is used. In another particular implementation, a comparison to an average capacitor voltage is used.

主权项

1. A method for regulating voltages in an electronic device, the method comprising:
balancing, by a circuit, a selected capacitor comprised in a plurality of capacitors by performing an operation from the group consisting of (i) injecting energy from an energy storage element into the selected capacitor and (ii) extracting energy from the selected capacitor and storing the extracted energy into the energy storage element; selecting, by the circuit, the operation based on a voltage across the selected capacitor and an average voltage, the average voltage being an average of voltages across capacitors of a set of capacitors from the plurality of capacitors; and regulating, by the circuit, a current of the energy storage element by periodically monitoring the current and applying a voltage across a combination of capacitors from among the plurality of capacitors to the energy storage element based on a comparison of the current with a threshold current.