Advantages And Disadvantages Of Direct Torque Control (DTC)

In 1980‘s, a new control technique was introduced in the field of electrical engineering especially in power electronics and motor drives to control the performance of induction motor. This method is called direct torque control (DTC), which was proposed by Isao Takashi and Noguchi [1]. DTC method is simpler in structure configuration and easy to control the induction machine in aspect of the dynamic performance response [1]. The initial concept of controlling the performance of the motor is taken from field oriented control (FOC). In early 1970, this method was implemented to control many applications such as lift, automation robot, traction, conveyor and others. But, this method is more complex and difficult to maintain because it requires

Many research has been conducted to overcome the several disadvantages found in the DTC scheme, from which most important is variable switching frequency [4] notably at low speed condition. Now many researchers are more focusing on how to improve the performance of induction machine in terms of dynamic torque response in different speed operations condition. There are many solutions to enhance the quality of performance of induction machine, either from creating a new algorithm, upgrading hardware system or changing the another processor with a sampling period smaller [5]-[9]. In 1990s sees the emergence of technologies that require higher level of power and voltage so multilevel inverter has been highlighted as the solution at such level of operation, because it offers several advantages such as very low harmonic distortion, low dv/dt, no output filter requirement etc. [13]. Due to the continuously evolving industrial applications that need high power and voltage operating level as well as high performance of machines applications, researchers have proposed to extend or adapt the traditional DTC scheme to multilevel inverter topologies. This means that the multilevel inverters are replacing the conventional three-phase inverters that have been previously used in the traditional DTC configuration to supply the stator voltage for