A Novel Optimal PI Parameter Tuning Strategy to Improve Constant Switching Performance of Direct Torque Control

Author(s):  
Sundram Ramahlingam ◽  
Auzani Jidin ◽  
Tole Sutikno

<p>This paper presents a novel method of optimal Propotional-Intergral (PI) controller’s parameter tuning strategy in-order to improve the Constant Switching Performance of 3-phase DTC shceme. The Direct Torque Control (DTC) sheme is acknowledged to provide fast decoupled control over the torque output and stator flux via a simple control structure. However, DTC sheme has two major downsides, which are the inconsistent inverter switching frequency and high torque output ripple. The main reason that contributes to these tribulations is the usage of hysteresis comparators in order to control the output torque. The realization of PI based controller method as replacement of hyterisis controller in DTC system able to provide significant solutions to over come the fall back while retaining the simple control structure of conventional DTC. The combination usage of higher sampling controller DS1004 and also 3-level CHMI in this system can further minimize the output torque ripple by providing higher resolution with lower digital error and greater number of vectors. This paper presents detail explanation and calculation of optimal PI parameter tuning strategy consecutively to enhance the performance of 3-level DTC system. In order to verify the feasibility of the proposed method experimentation, the proposed method is compared with convention DTC system via simulation and experiment results.</p>


Author(s):  
Sundram A/l Ramahlingam ◽  
Auzani Bin Jidin ◽  
Tole Sutikno ◽  
L. Logan Raj

This paper presents the advantage of using optimal PI parameter tuning strategy of constant switching method in the three phase Direct torque control (DTC) scheme. The DTC system is known to offer fast decoupled control of torque and flux via a simple control structure. Nevertheless, DTC system has two major drawbacks, which are the variable inverter switching frequency and high torque output ripple. The major factorthat contributes to these problems the usage of hysteresis based comparators to control the output torque. The implementation of PI based constant switching method in DTC able to solve these problems while retaining the simple control structure of conventional DTC. The combination usage of 3-level CHMI in this system can further minimize the output torque ripple by providing greater number of vectors. This paper presents detail explanation and calculationof optimal PI parameter tuning strategyconsecutively to enhance the performance of 3-level DTC system. In order to validate the feasibility, the proposed method compared with convention DTC system via simulation and experiment results.



2010 ◽  
Vol 29-32 ◽  
pp. 2200-2204
Author(s):  
Xue Zhi Hu ◽  
Guang Qun Nan

Traditional induction motor direct torque control system with the hysteresis loop controller, based on torque error, set the amplitude error to select the inverter switching state, is a Band-Band Control , torque error and stator flux error of level can not be distinguished, switching frequency is not constant, over-sector current and the distortion flux linkage can product low speed torque ripple, affecting the control of the system effect. The paper proposed fuzzy PI control of induction motor direct torque control scheme, a system of principles was introduced, controller parameters was designed by fuzzy theoretical. Finally a full-digital experimental system was built with the TMS320F2812 as the master chip and PM30CSJ060 as an inverter main circuit. Results show that the dynamic and static performance and running smoothly with low-speed is verified.



Author(s):  
Xiaoxin Hou ◽  
Mingqian Wang ◽  
Guodong You ◽  
Jinming Pan ◽  
Xiating Xu ◽  
...  

The traditional direct torque control system of permanent magnet synchronous motor has many problems, such as large torque ripple and variable switching frequency. In order to improve the dynamic and static performance of the control system, a new torque control idea and speed sensorless control scheme are proposed in this paper. First, by deriving the equation of torque change rate, an improved torque controller is designed to replace the torque hysteresis controller of the traditional direct torque control. The improved direct torque control strategy can significantly reduce the torque ripple and keep the switching frequency constant. Then, based on the improved direct torque control and considering the sensitivity of the stator resistance to temperature change, a speed estimator based on the model reference adaptive method is designed. This method realizes the stator resistance on-line identification and further improves the control precision of the system. The performance of the traditional direct torque control and the improved direct torque control are compared by simulation and experiment under different operating conditions. The simulation and experimental results are presented to support the validity and effectiveness of the proposed method.



Author(s):  
Huzainirah Ismail ◽  
Fazlli Patkar ◽  
Auzani Jidin ◽  
Aiman Zakwan Jidin ◽  
Noor Azida Noor Azlan ◽  
...  

<p>Direct Torque Control (DTC) is widely applied for ac motor drives as it offers high performance torque control with a simple control strategy. However, conventional DTC poses some disadvantages especially in term of variable switching frequency and large torque ripple due to the utilization of torque hysteresis controller. Other than that, performance of conventional DTC fed by two-level inverter is also restricted by the limited numbers of voltage vectors which lead to inappropriate selection of voltage vectors for different speed operations. This research aims to propose a Constant Switching Frequency (CSF) torque controller for DTC of induction motor (IM) fed by three-level Neutral-Point Clamped (NPC) inverter. The proposed torque controller utilizes PI controller which apply different gain for different speed operation. Besides, the utilization of NPC inverter provides greater number of voltage vectors which allow appropriate selection of voltage vectors for different operating condition. Using the proposed method, the improvement of DTC drives in term of producing a constant switching operation and minimizing torque ripple are achieved and validated via experimental results.</p>



2011 ◽  
Vol 7 (1) ◽  
pp. 42-49
Author(s):  
Turki Abdalla ◽  
Haroution Hairik ◽  
Adel Dakhil

Among all control methods for induction motor drives, Direct Torque Control (DTC) seems to be particularly interesting being independent of machine rotor parameters and requiring no speed or position sensors. The DTC scheme is characterized by the absence of PI regulators, coordinate transformations, current regulators and PWM signals generators. In spite of its simplicity, DTC allows a good torque control in steady state and transient operating conditions to be obtained. However, the presence of hysterics controllers for flux and torque could determine torque and current ripple and variable switching frequency operation for the voltage source inverter. This paper is aimed to analyze DTC principles, and the problems related to its implementation, especially the torque ripple and the possible improvements to reduce this torque ripple by using a proposed fuzzy based duty cycle controller. The effectiveness of the duty ratio method was verified by simulation using Matlab/Simulink software package. The results are compared with that of the traditional DTC models.



Author(s):  
Dris Ahmed ◽  
Bendjebbar Mokhtar ◽  
Belaidi Aek

In this paper, DTC is applied for two-level inverter fed IM drives based on neuronal hysteresis comparators and The Direct Torque Control (DTC) is known to produce quick and robust response in AC drive system. However, during steady state, torque, flux and current ripple. An improvement of electric drive system can be obtained using a DTC method based on ANNs which reduces the torque and flux ripples, the estimated the rotor speed using the KUBOTA observer method based on measurements of electrical quantities of the motor. The validity of the proposed methods is confirmed by the simulation results.The THD (Total Harmonic Distortion) of stator current, torque ripple and stator flux ripple are determined and compared with conventional DTC control scheme using Matlab/Simulink environment.



Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 374
Author(s):  
Tomas Esparza Sola ◽  
Huang-Jen Chiu ◽  
Yu-Chen Liu ◽  
Arief Noor Rahman

This paper presents a method to extend the DC bus utilization on an induction motor (IM) by using a combination of Space-Vector Modulated Direct Torque Control (DTC–SVM) and conventional DTC. The scheme proposed in this paper exploits the advantages of both control methods. During the linear region, it allows for a low torque ripple and low current harmonic distortion (THD). During the overmodulation region, it allows for the fastest torque response up to the six-step operation region. In both regions, there is complete independence of the motor parameters. The paper describes a way to provide a smooth transition between the two control schemes. Non-linearities affect the stator flux angle estimation, which leads to the inability to decouple torque and flux. To overcome this problem, a novel PI-based control scheme as well as a simplification on the decoupling terms’ calculation are proposed. Simulation and experimental results are presented to verify the feasibility of the proposed method.



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