Direct Torque Control with Space Vector Modulation (DTC-SVM) of ...

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Introduction The main requirements for high performance PWM inverter-fed PMSM drive can be formulated as follows: • operation with and without mechanical motion sensor, • fast flux and torque response, • available maximum output torque in wide range of speed operation region, • constant switching frequency, • uni-polar voltage PWM, • low flux and torque ripples, • robustness to parameters variation, • four quadrant operation. To meet the above requirements, different control methods can be used [3,4,10]. Variable Frequency Control Scalar based controllers Vector based controllers V/Hz=const with stabilization loop Field Oriented (FOC) Direct Torque Control (DTC) PM (rotor) Flux Oriented (RFOC) Stator Flux Oriented (SFOC) Direct Torque Control with Space Vector Modulation (DTC-SVM) Circular flux trajectory (Takahashi) Figure 1.3 Classification of PMSM control methods. The general classification of the variable frequency control for PMSM is presented in Fig. 1.3. The PMSM control methods can be divided into scalar and vector control. According to [3], in scalar control, which based on a relation valid for steady states, only the magnitude and frequency (angular speed) of voltage, currents, and flux linkage space vectors are controlled. Thus, the control system does not act on space vector position during transient. Therefore, this control is dedicated for application, where high dynamics is not demanded. Contrary, in 4
Introduction vector control, which is based on relation valid for dynamics states, not just magnitude and frequency (angular speed), but also instantaneous position of voltage, current and flux space vectors are controlled. Thus, the control system adjust the position of the space vectors and guarantee their correct orientation for both steady states and transients. The scalar constant V/Hz control for PMSM without damper winding (squire cage) is not simple as for induction motor. It requires additional stabilization control loop, which can be provide by feedback from: rotor velocity perturbation, active power or DC-link current perturbation [9]. The most popular vector control method developed in 70s, known as field oriented control (FOC) [31] gives the permanent magnet synchronous motor high performance. In this method the motor equation are transformed in a coordinate system that rotates in synchronism with permanent magnet flux. It allows separately and indirectly control flux and torque quantities by using current control loop with PI controllers like in well known DC machine control [3]. In search of a simpler and more robust high performance control system in 80s new vector control called direct torque control (DTC) was developed [50]. It was innovative studies at this time and completely different approach which depart from the idea of coordinate transformation and the analogy with DC motor control. It allows direct control flux and torque quantities without inner current control loops. Using bang-bang hysteresis controllers for flux and torque control loops made this control concept very fast and not complicated. However, the main disadvantage of DTC is fast sampling time required and variable switching frequency, because of hysteresis based control loops. In order to eliminate above disadvantages and kept basic control rules of classical DTC, at the beginning of 90’s a new developed control technique called direct torque control with space vector modulator (DTC- SVM) has been introduced [54,55]. However, from the formal consideration this method can also be viewed as stator flux oriented control (SFOC). This control employed instead of hysteresis controller as for classical DTC, the PI controllers and space vector modulator (SVM). It allows to achieve fixed switching frequency, what considerably reduce switching losses as well as torque and current ripples. Also requirement of very fast sampling time is eliminated [113,115,117]. Therefore, this new method is subject of this thesis. In spite of many control strategies there is no one which may be considered as standard solution. 5
Page 1 and 2: POLITECHNIKA WARSZAWSKA WARSAW UNIV
Page 3 and 4: Contents Table of Contents Chapter
Page 5 and 6: Introduction Chapter 1 INTRODUCTION
Page 7: Introduction to surface-mounted mac
Page 11 and 12: Introduction presented and studied.
Page 13 and 14: Modeling and control modes of PM sy
Page 39 and 40: Voltage source PWM inverter for PMS
Page 57 and 58: Control methods of PM Synchronous m
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Control methods of PM Synchronous m
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Direct Torque Control with Space Ve
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Sensorless Speed Direct Torque Cont
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DSP implementation of DTC-SVM contr
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Summary and closing conclusion Chap
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Appendices APPENDICES A1 Rotor and
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Appendices ⎡ ⎤ ⎢ 1 0 ⎥ ⎡K
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Appendices i(t1->t0)+=it1 it1: it1=
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Appendices A7 PWM technique - six s
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List of symbol List of symbols Symb
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References Books and PhD-Thesis 1.
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References 39. J.-I. Itoh, N. Nomur
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References 74. N. Ertugrul, P. Acar
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References 108. D. Świerczyński,
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Direct Torque Control with Space Vector Modulation (DTC-SVM) of ...

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