Analysis of RMS current on DC-link capacitor with single-shunt current sensing system

A single-shunt current sensing technique is widely used in industrial system to reduce the cost and mounting space of current sensors in an inverter. In addition, a pulse shift control technique, which maintains the pulse duration and achieves reliable current detection, is used in a single-shunt current sensing system. In this paper, the RMS current on the DC-link capacitor with a pulse shift control technique was analyzed. The analysis results showed that the RMS current on the DC-link capacitor in the single-shunt current sensing system increases over 50% compared to a conventional three-phase current sensing system, in case of a low modulation factor. In addition, the rise in temperature of the DC-link capacitor with or without the single-shunt current sensing was verified by examination. An advanced single-shunt current sensing technique for a redundant inverter system to reduce the RMS current on the DC-link capacitor and the audible noise is also proposed in this paper.