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

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Sensorless Speed Direct Torque Control with Space Vector Modulation (DTC-SVM) I =∆ I sin 2γ (6.4) sβ s m where I s is DC component in Is α and ∆ Is amplitude of fluctuated component. The current components in α, β can be modeled as an average value of I s plus some offset value ∆ Is , as a function of the mechanical position γ m . Fig. 6.4 shows the current components given in Eq. (6.1-2), which are function of the phase angle 2γ m . Solving those Eqs. (6.1 and 6.2) in respect to mechanical rotor position, two domains of mechanical rotor position can be obtained as: Isβ γ m1 = (6.5) 2( I − I ) sα s = Isβ γ m2 2( I − I ) + π (6.6) sα s The estimated rotor positions for other combination of sign( I s ) summarized in Table 6.7. + and sign( I s ) − are 15π π − 8 8 7π 9π − 8 8 π 3π − 8 8 9π 11π − 8 8 3π 5π − 8 8 11π 13π − 8 8 5π 7π − 8 8 13π 15π − 8 8 I sα − I s + I sβ + + + − − − − I sα − I s − I sβ γ m + I sβ 2( I sα − I s ) I sβ + π 2( I sα − I s ) I sα + I s π − + 2I sβ 4 I sα + I s 5π − + 2I sβ 4 I sβ π + 2( I s α − I s ) 2 I sβ 3π + 2( I s α − I s ) 2 I sα + I s 3π − + 2I sβ 4 I sα + I s 7π − + 2I sβ 4 Table 6.7. Mechanical rotor position calculations. Long pulsewise voltage test This test help us to choose the proper estimated value of mechanical rotor position from two values calculated during the short pulse wise voltage test. 126
Sensorless Speed Direct Torque Control with Space Vector Modulation (DTC-SVM) This test is based on the saturation effect of magnetic circuit. If the long pulse will send in direction of north pole of PM, the current response will be slower, and, if current response will be faster that the previous, it means that it is south pole. 6.3 Stator flux estimation methods Flux estimation is an important task in implementation of high-performance DTC-SVM motor drives. Vector control method of PMSM drive needs knowledge about actual value of the stator flux magnitude and position as well electromagnetic torque. Also, the flux estimation is needed to calculate the actual rotor speed for sensorless operation. 6.3.1 Overview Many different technique has been developed for PMSM flux estimation [107]. Generally, they may be divided into two groups: open loop estimators and closed loop estimators/observers. Most of these method are based on so called “current model” or “voltage model” [110,113]. In fact closed loop estimators/observers are based on the current or voltage model with an error correction loop, which drives error between two flux models to zero in steady state. However, an observer has its own dynamics, is sensitive to parameter changes, and has to be carefully designed for individual drives. Therefore, for commercially manufactured drives is to complicated and impractical. This is the reason why in this Chapter only open loop flux estimators will be considered. 6.3.2 Current model based flux estimator The block scheme of the current based flux model is presented in Fig. 6.7. It requires: • knowledge of PMSM machine inductance L , L , • speed or position signal, • PMSM phase currents. d q This kind of flux estimator served in experimental test as a master (standard) to run the DTC-SVM scheme with speed sensor. 127
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POLITECHNIKA WARSZAWSKA WARSAW UNIV
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Contents Table of Contents Chapter
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Introduction Chapter 1 INTRODUCTION
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Introduction to surface-mounted mac
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Introduction vector control, which
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Introduction presented and studied.
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Modeling and control modes of PM sy
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Voltage source PWM inverter for PMS
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Control methods of PM Synchronous m
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Direct Torque Control with Space Ve
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Page 79 and 80: Direct Torque Control with Space Ve
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Page 167 and 168: Appendices APPENDICES A1 Rotor and
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Page 173 and 174: Appendices A7 PWM technique - six s
Page 175 and 176: List of symbol List of symbols Symb
Page 177 and 178: References Books and PhD-Thesis 1.
Page 179 and 180: 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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