A low-cost three phase current sensor module with a novel modulated interface

Current sensors have an important part in the technical world. A special part is by photovoltaic. The efficiency of the system can only increase by means of the MPP-Tracking with high precise current sensor. Furthermore, the inverter with the three phases should measure balance or unbalance effects. In this case, this paper will present a novel system (AC-DI module). This module has four high precise single current sensors, which are based on the measuring module (IHM-A-1500). Compared to conventional current sensors, the proposed topology is advantageous because of its high resolution throughout its full measurement range, thus reducing offsets to a minimum. This aim is reached through active offset compensation using an analog/digital chopper/de-chopper. A further advantage is the excellent suppression of 1/f noise and a low noise density (35 nV/√Hz) down to the DC-threshold. Common current sensors may be replaced with this technology whose one output is likewise analog. The power supply requirements are also far lower than for standard topologies as only a single supply is needed. In addition to that is the novel modulation method, which codes directly the measured value in a “digital current value”.