Industrial Inverter Current Sensing With Three Shunt Resistors: Limitations and Solutions

As inverter powered variable speed drives become popular and technically mature, cost control becomes the core competence for inverter manufacturers. Under minimum performance requirement specifications, the inverter is tailored in every aspect, from the main power device to various sensors to enhance its competitiveness. This paper mainly focuses on various issues associated with the downgrade of current sensors from standard Hall sensor to shunt resistors. The limitation of current sensing by shunt resistors is reviewed and method to expand the maximum achievable modulation index on the vector plane is implemented. Experiments are conducted to verify the analysis and to validate the effectiveness of the reconstruction algorithm.