18-04-2011, 02:22 PM
submitted by :
Ashish Sharma
Ashok Kr. Kumawat
Balraj Sharma
Satyanarayan Agarwal
Tarun Mandawat
[attachment=12299]
WHAT IS DTC ?
Direct torque control is known to produce quick and robust response in AC drive system.
Direct Torque Control describes the way in which the control of torque and speed are directly based on the electromagnetic state of the motor.
Direct Torque Control is a direct hysteresis stator flux and electromagnetic torque control which triggers one of the eight available discrete space voltage vectors generated by a Voltage Source
DTC Schematic
Main Functional Parts of DTC:
DTC controller
o Torque and flux estimator
o Hysteresis band
o Switching table
Speed controller
Braking chopper
Voltage source inverter
Induction motor
Three phase rectifier
DTC controller
Speed Controller
MATLAB/ Simulink Analysis
DTC Controller
Speed Controller
Induction motor parameters
Rotor type: squirrel-cage Nominal power: 149.2e3 VA Voltage (line to line): 460V Stator resistance: 14.85e-3ohm Stator inductance: 0.3027e-3H Rotor resistance: 9.295e-3ohm Rotor inductance: 0.3027e-3H Mutual inductance: 10.46e-3H Inertia: 3.1kg.m2 Friction factor: 0.08N.m.s Pole pairs: 02
Direct Torque Control Scheme Results
Improvement Method in DTC
1. Modified DTC
2. 12 Sector DTC
3. Direct Torque Fuzzy Control
1. Modified DTC (m_DTC)
Behavior of flux and torque in different zone
Look Up Table of Classical and Modified DTC
2. Twelve sector modified DTC (12_DTC)
Switching Table for 12_DTC
Direct Torque Fuzzy Control
The main objective of direct torque fuzzy control is to reduce the ripples and to improve the speed performance.
Direct Torque Fuzzy Control Schematic
Principle of Direct Torque Fuzzy Control
The DTFC of induction motor drive is designed to have three fuzzy input variables and one output control variable to achieve fuzzy logic based DTC of the induction machine.
The proposed DTFC consists of fuzzification, rule base, data base, decision making and defuzzification blocks.
Block Diagram of DTFC
Flux Linkage Error Fuzzification
Electromagnetic Torque Error Fuzzification
Stator Flux Linkage Angle Fuzzification
Space Vector Voltage Fuzzification
DTFC Rule Base Design
Surface Viewer of Fuzzy Fis
Results: Conventional DTC
Modified DTC (m_DTC)
12 sector DTC (12_DTC)
Direct Torque Fuzzy Control
Comparison
Torque ripples are reduced to a great extent by using modified look-up table and 12 sectors in Comparison to conventional DTC.
Nonlinearities are reduced in rotor speed by using modified look-up table and 12 sectors zone.
Settling time of rotor speed is reduced by using modified look-up table and 12 sector zone in comparison to conventional DTC.
Conclusions
Direct Torque Control is supposed to be one of the best controllers for driving any induction motor.
Method of DTC also allows the independent and decoupled control of motor torque and motor stator flux.
It can be concluded that by means of changing the table can be remarkably improved the DTC performance.
It can be concluded that fuzzy logic method is very promising.
Future Scope
Develop a completely auto adaptive controller.
Find optimum controllers, not only for torque ripple reductions, but also for reducing EMI and for increasing energy savings from the mains.
Sensor less FLDTC implementation, just sensing two currents and the DC voltage.
Ashish Sharma
Ashok Kr. Kumawat
Balraj Sharma
Satyanarayan Agarwal
Tarun Mandawat
[attachment=12299]
WHAT IS DTC ?
Direct torque control is known to produce quick and robust response in AC drive system.
Direct Torque Control describes the way in which the control of torque and speed are directly based on the electromagnetic state of the motor.
Direct Torque Control is a direct hysteresis stator flux and electromagnetic torque control which triggers one of the eight available discrete space voltage vectors generated by a Voltage Source
DTC Schematic
Main Functional Parts of DTC:
DTC controller
o Torque and flux estimator
o Hysteresis band
o Switching table
Speed controller
Braking chopper
Voltage source inverter
Induction motor
Three phase rectifier
DTC controller
Speed Controller
MATLAB/ Simulink Analysis
DTC Controller
Speed Controller
Induction motor parameters
Rotor type: squirrel-cage Nominal power: 149.2e3 VA Voltage (line to line): 460V Stator resistance: 14.85e-3ohm Stator inductance: 0.3027e-3H Rotor resistance: 9.295e-3ohm Rotor inductance: 0.3027e-3H Mutual inductance: 10.46e-3H Inertia: 3.1kg.m2 Friction factor: 0.08N.m.s Pole pairs: 02
Direct Torque Control Scheme Results
Improvement Method in DTC
1. Modified DTC
2. 12 Sector DTC
3. Direct Torque Fuzzy Control
1. Modified DTC (m_DTC)
Behavior of flux and torque in different zone
Look Up Table of Classical and Modified DTC
2. Twelve sector modified DTC (12_DTC)
Switching Table for 12_DTC
Direct Torque Fuzzy Control
The main objective of direct torque fuzzy control is to reduce the ripples and to improve the speed performance.
Direct Torque Fuzzy Control Schematic
Principle of Direct Torque Fuzzy Control
The DTFC of induction motor drive is designed to have three fuzzy input variables and one output control variable to achieve fuzzy logic based DTC of the induction machine.
The proposed DTFC consists of fuzzification, rule base, data base, decision making and defuzzification blocks.
Block Diagram of DTFC
Flux Linkage Error Fuzzification
Electromagnetic Torque Error Fuzzification
Stator Flux Linkage Angle Fuzzification
Space Vector Voltage Fuzzification
DTFC Rule Base Design
Surface Viewer of Fuzzy Fis
Results: Conventional DTC
Modified DTC (m_DTC)
12 sector DTC (12_DTC)
Direct Torque Fuzzy Control
Comparison
Torque ripples are reduced to a great extent by using modified look-up table and 12 sectors in Comparison to conventional DTC.
Nonlinearities are reduced in rotor speed by using modified look-up table and 12 sectors zone.
Settling time of rotor speed is reduced by using modified look-up table and 12 sector zone in comparison to conventional DTC.
Conclusions
Direct Torque Control is supposed to be one of the best controllers for driving any induction motor.
Method of DTC also allows the independent and decoupled control of motor torque and motor stator flux.
It can be concluded that by means of changing the table can be remarkably improved the DTC performance.
It can be concluded that fuzzy logic method is very promising.
Future Scope
Develop a completely auto adaptive controller.
Find optimum controllers, not only for torque ripple reductions, but also for reducing EMI and for increasing energy savings from the mains.
Sensor less FLDTC implementation, just sensing two currents and the DC voltage.