Patent ID: 8120885

Claim:
A circuit, comprising: a first switch serially connected to a first discharge resistor, the first switch and the first discharge resistor directly connected to a positive direct current (DC) bus; a second switch serially connected to a second discharge resistor, the second switch and the second discharge resistor directly connected to a negative DC bus; a capacitor bank for storing a positive DC voltage and a negative DC voltage, the capacitor bank including a first capacitor in parallel with the first switch and the first discharge resistor, and a second capacitor in parallel with the second switch and the second discharge resistor, the first capacitor directly connected to the positive DC bus and the second capacitor directly connected to the negative DC bus; a first sensing unit connected in parallel with the first capacitor and directly connected to the positive DC bus; and a second sensing unit connected in parallel with the second capacitor and directly connected to the negative DC bus, wherein the first and the second sensing units are configured to measure a voltage across the first capacitor and the second capacitor, respectively, and sense an overvoltage; and wherein, in response to a sensed overvoltage across the first capacitor, the first switch operates independently from the second switch to discharge the positive DC voltage through the first discharge resistor and, in response to a sensed overvoltage across the second capacitor, the second switch operates independently from the first switch to discharge the negative DC voltage through the second discharge resistor.