Generalised look‐up table concept for direct torque control in induction drives with multilevel inverters

Abstract

This study deals with direct torque control (DTC) of induction motor drives when a multilevel inverter is involved. The proposed control technique is finalised to reduce the amplitude of torque oscillations and to improve the motor dynamic response regardless of operating speed conditions while assuring a satisfactory input current distortion. This is achieved by using a special look-up-table built with a novel approach. The control itself is based on the application in each sampling interval of one or two voltage vectors suitably selected, in order to ensure low electromagnetic torque ripple in steady-state operations and fast dynamic behaviour in transient operations. In the algorithm, the converter voltage vectors selection is carried out by using a novel look-up table whose entry points are computed by means of a specialised relation, starting from the outputs of multilevel hysteresis controllers. The suggested method, suitable for a generic multilevel inverter, is detailed for a neutral point clamped three-level inverter. The proposed algorithm is validated by several numeric a lr e s u l t s ,a n dc o m p a r e dw i t haD T Ca l gorithm based on a traditional threespeed range look-up tables. Finally, some experimental results, obtained with a scale laboratory setup, are shown, discussed and compared with the numerical ones.

Robot Trajectory Tracking Control Based on Look-up Table Method

“…In this paper, a simple and applicable look-up table [20] based trajectory tracking method is proposed for mobile robot. This scheme can be applied to not only the line or nonlinear trajectory curve but also the trajectory that a series of coordinate sequences with strong nonlinearity or unsatisfied single curve description.…”

Torque Ripple Reduction in Three-Level Inverter-Fed Permanent Magnet Synchronous Motor Drives by Duty-Cycle Direct Torque Control Using an Evaluation Table

“…Unsmooth vector switching means a direct "jump" between the positive and negative buses in a phase voltage, reducing both the quality of the output voltage and the accuracy of the control. Numerous improved algorithms have been proposed in the literature [8]- [16] to solve the problem of torque ripples in the standard 3L-DTC. These algorithms can be divided into single vector-based DTC (SV-DTC), DTC with discrete space vector modulation (DSVM-DTC), and duty cycle-based DTC (DC-DTC) according to the vector output mode.…”

“…DC-DTC employs several basic voltage vectors in each control period. The duration of these basic vectors are calculated in accordance with the criterion of the minimum torque ripples [15], [16]. In [16], the switching table and the torque hysteresis controller were redesigned, and two voltage vectors were used to control the motor.…”

“…The duration of these basic vectors are calculated in accordance with the criterion of the minimum torque ripples [15], [16]. In [16], the switching table and the torque hysteresis controller were redesigned, and two voltage vectors were used to control the motor. The first basic voltage vector was selected on the basis of the switching table, and the second voltage vector was generated using the predicted duty cycle based on the mathematical model of the motor.…”

Induction Motor Parameter Estimation Using Sparse Grid Optimization Algorithm

“…Among many highperformance induction motor control methods, indirect fieldoriented control (FOC) [1] and direct torque control (DTC) [2] are of particular note in speed sensorless control methods. For both schemes, the effective induction motor control relies on the precise knowledge of the parameters of the equivalent circuit.…”