An evaluation of two Direct Current Control methods implemented with LabVIEW on a FPGA

This paper presents a comparison between two Direct Current Control (DCC) strategies for controlling a PMSM. The strategies are implemented on a Field Programmable Gate Array (FPGA) using national instruments compactRIO cRIO-9022 system. The first strategy operates in the Rotor Reference Frame (RRF) and uses two hysteresis squares to control the derivative of the current. Voltage vector is chosen based on the sign of the current errors in regard to the desired current value in the RRF. The second strategy is implemented in the Stator Reference Frame (SRF) and uses two hysteresis circles to control the current. Voltage vector is chosen based on the angular error in regard to the desired value in the SRF. Test sequences are conducted on a PMSM to compare the performance of the control strategies. The results show that the DCC in the SRF performs the given test sequences with a higher precision than the control strategy implemented in the RRF. The results also imply that the dynamic hysteresis bands are better suited for the control in the SRF than the control in the RRF.