Design and simulation of direct torque control of induction motors using VHSIC Hardware Description Language (VHDL)

Induction motors are currently used in many industrial applications. Thus, their control techniques have received a lot of interest. An efficient method of induction motor control is the Direct Torque Control (DTC). It is considered particularly interesting since it is independent of machine rotor parameters and requires no speed or position sensors. This paper presents a simulation of a DTC strategy for three-phase induction motors based on the Field Programmable Gate Array (FPGA) technology. The real controller is not experimentally tested. A specific methodology for the hardware description language in VHSIC Hardware Description Language (VHDL) is presented. This paper summarizes the prior work before implementing the experimental FPGA control of an induction motor. This methodology allows one to verify the behavior of the VHDL codes before their implementation, reducing the risks of significant changes when implemented. The VHDL design technique for DTC-based speed control is designed through the descriptions of coordinate transformation, speed controller, stator flux and torque estimator, stator flux and torque controller, and stator flux position detector. The simulation is performed using the MATLAB/Simulink, DSP Builder, and Quartus II software, on an Altera DE2-115 board. Simulation results verify the validity of the proposed method.   Key words: Digital control, induction motor, digital signal processing, VHSIC Hardware Description Language (VHDL).