Properties of selected direct torque control methods of induction motor

Abstract

Direct torque control is one of modern methods of A.C. machines control. The direct torque control methods have been developed and experimentally tested at the Department of Electronics too. In the paper, important quantities are described which were measured on a real induction motor drive with different direct torque control methods. The basic properties of the methods are compared with the Takahashi method.

Matrix converter sliding mode based control for induction motor drive

“…where A s is the main state space matrix (21), and b represents the influence of action vectors (22). …”

“…When we assume that the supplying source has a certain maximum we can find the limit where the source will not be able to deliver enough voltage to increase the machine's torque [21]. When we substitute torque (23) for (26) we obtain equation (28) that is not quite legible, but it also represents the torque/slip-speed characteristic of the machine: By substituting (28) into equation for i q from (20) we obtain the voltage limit characteristic expressed in the flux-current plane as (29).…”

“…Now let us look in more detail at the behavior of the "uncontrolled" component i d . It can easily be analyzed as a derivative of i d from (21).…”

“…This area has been found to be independent of the mechanical speed, supplying voltage vector and even the id current. It could be supposed in the case of torque control that the working area limitation would depend on more factors [21]. Let us investigate the existence condition of sliding mode torque control.…”

Energy optimization of an electric car using losses minimization and intelligent predictive torque control

“…DTC was invented in 1986 by Takahashi. 6 This method maintains the torque and the modulus of the stator vector flux inside a hysteresis band by the choice of voltage vectors provided by the inverter. The generation of switching commands is done with the aid of a switch table.…”