Mobile QR Code QR CODE : The Korean Institute of Power Electronics
Title A DTC-PWM Control Scheme of PMSM using an Approximated Voltage Function of Voltage Vector
Authors YunChang Kwak ; Dong-Hee Lee
DOI 10.6113/TKPE/2015.20.5.421
Page pp.421-428
ISSN 1229-2214
Keywords DTC-PWM(Direct Torque Control?Pulse Width Modulation); PMSM; Approximated voltage function; Voltage vector analysis
Abstract An advanced direct torque control (DTC) with pulse width modulation (PWM) method is presented in this paper. The duty ratio calculation of the selected voltage vector is based on the voltage functions of the selected voltage vector according to the sector angle. The proposed DTC uses a conventional DTC scheme with six sector divisions and switching rules. However, the winding voltages are supplied by the PWM approach. Furthermore, the duty ratio of the switching voltage vector is determined by the flux, torque error, and motor speed. The base voltage that shall determine the duty ratio can be calculated by approximate voltage functions according to the voltage angle. For the calculation of base voltages, second-order quadratic functions are used to express the output voltage of the selected voltage vector according to voltage angle. The coefficients for the second?order quadratic functions are selected by the voltage vector, which is determined by the switching rules of the DTC. In addition, the voltage functions are calculated by the coefficients and voltage angle between the voltage vector and rotor position. The switching voltages from the calculated duty ratio can supply the proper torque and flux to reduce the ripple and error. The proposed control scheme is verified through practical experimental comparisons.