Indirect Multiple DC Link Current Sensing Using Op-Amp Circuits in a Three-Phase Three-Level PWM Inverter

This paper presents an accurate, reliable and cost-efficient multiple DC link current sensing solution for phase current reconstruction in multi-phase multi-level inverter with small planar bus bar links between switching devices and DC link. An indirect current sensing technique using single current sensor with operational amplifier circuits is described on a 3-phase 3-level inverter example. A comparison between single sensor top and sensorless neutral DC link current sensing circuit is presented by evaluating cost efficiency, current unmeasurable areas and accuracy, using simulation and experimental results. The proposed method can be used for sensorless phase current estimation and fault detection in electrical drives.