A New Current Sensing Scheme for PMSM Drive Inverters in Automotive Applications 2013-01-0038

This paper presents a low-cost two shunt resistor current sensing method for PMSM driving inverter. There are two current sensing methods using shunt resistor as Single Current-Shunt Inverter (SCSI) or Three Current-Shunt Inverter (TCSI). SCSI needs only one shunt resistor to get the current data, it is a cost-effective one. But it has a limitation in a low speed current sensing and it has to be guaranteed minimum dwell time on high-side switch to get proper current information. And TCSI needs three shunt resistors and it allows simultaneous and independent measurement for each phase current. But TCSI has immeasurable region in high speed operation and has to guarantee enough time for zero voltage vector (T0) to get correct current data. To control 3 phase PMSM, at least two phases current data are needed and TCSI has better performance than SCSI. Using simplified TCSI, it is possible to reconstruct 3 phase current data with two shunt resistor even T0 does not long enough. It can be mixed scheme of SCSI and TCSI and can overcome the drawbacks of each scheme. And this paper proposes STCSI method and it has been verified with simulation results.