Yogesh Sapkota is a graduate Electrical and Computer Engineering student at Youngstown State University. He is interested in electronics, programming embedded systems and machine learning. Currently, he is working on developing a variable frequency drive for three-phase induction motor using Arty-A7 FPGA development board.
As the demands for electric vehicles, electric aircraft, Unmanned Aircraft Systems, and other motor-driven systems increase, high-performance motor drives employing variable frequency control with higher efficiency and reliability are becoming increasingly important parts of the ever-changing technology trend. This study discusses an FPGA-based variable frequency soft-starting motor drive for a three-phase induction motor. Variable frequency drive is realized based on Direct Digital Synthesis (DDS) technique. Gradually increasing the modulation index during the starting period enables the soft start of the induction motor to limit the inrush current. Controlling the soft-start period enables the reduction of the peak in-rush current. The Digilent Arty A7-35T Artix-7 FPGA Development board is used to realize the proposed motor drive. The performance of three different Pulse Width Modulation (PWM) techniques—Sinusoidal PWM, Third Harmonic Injected PWM, and Space Vector PWM—are analyzed and compared. The proposed architectures require only a small fraction of the FPGA’s resources. Simulation of the delta-connected three-phase load is carried out in MATLAB/ Simulink. The inverter output voltage and the load currents are analyzed for the harmonic contents. In the experimental realization, a four-pole squirrel cage delta-connected induction motor is utilized with a switching frequency of 4 kHz. The current and voltage characteristics of the induction motor are studied under different operating conditions to study the effects of dead time addition and different soft-starting duration. The matching of the simulation results and the experimental observations shows improved performance, higher efficiency, and greater reliability and making it possible to drive the motor more effectively with the proposed control scheme.
Attendees will learn about use of FPGA in developing PWM based control topologies—which show improved performance, greater reliability and efficiency—to drive three phase induction motor to be used in electric vehicles, electric aircrafts and other motor driven systems.
