Direct Power and Torque Control of AC/DC/AC Converter-Fed ...

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3. Vector Control Methods of AC/DC/AC Converter-Fed IM Drives – A Review U px U Lx = 0 − + 1 ILx sL + R U py − + U Ly = U Lm 1 sL + R I Ly Fig. 3. 13. Decoupled current loops of VSR in xy coordinates It simplifies the analysis and enables the derivation of analytical expressions for the parameters of current regulators. In Fig. 3. 14 a block diagram for a simplified current control loop in the synchronous rotating coordinates are presented. Because the same diagram applies to both the x and y axis regulators, the subscripts x and y are omitted. Control structure will operates in discontinuous environment (complete model in Saber, and implementation in DSP) therefore, is necessary to take into account the sampling period T S . It could be done by sample & hold – S&H block. Moreover, the statistical delay of the PWM generation T = 0. 5T should be taken into account PWM S (block VSC). In the literature [13], [83] the delay of the PWM is approximated from zero to two sampling periods T S . Further, K C = 1 is the VSC gain, τ 0 is a dead time of the VSC ( τ 0 = 0 for ideal converter). I Lcc sT pf 1 + 1 I Lc + − 1 sT S + 1 ( sT ) K + sT Pi1 Ii1 1 Ii1 K e sT −sτ 0 c PWM + 1 + U Ldist − 1 sL + R I L Fig. 3. 14. Block diagram for a decoupled current control loop in the synchronous rotating reference frame 48
3. Vector Control Methods of AC/DC/AC Converter-Fed IM Drives – A Review The block S&H and VSC could be joined in one block S&H+VSC. Where, sum of their time constants is expressed by: τ = T T . (3. 25) Σi S + PWM So, the model of Fig. 3. 14 can be simplified as shown in Fig. 3. 15. I Lcc sT pf 1 + 1 I Lc + − ( sT ) K + sT Pi1 Ii1 1 Ii1 − τ0 K e s c sτ + 1 Σ + U Ldist − K sT RL RL + 1 I L Fig. 3. 15. Modified block diagram of Fig. 3. 14 Please note that, τ is a sum of small time constants, T RL = L / R is a large time Σi constant and K RL = 1/ R is a gain of input choke. Hence, T RL gives a dominant pole. Between several methods of analysis, there are two simple way for the controller parameters design: modulus optimum - MO and symmetry optimum – SO [134]. With assumption that disturbance U L = const. , open loop transfer function can be derived as: G Oi () s K = sT Ii1 Pi1( 1+ sTIi 1) K RL ( s + 1)( sT + 1) τ Σ i RL (3. 26) sT With simplification ( RL ) RL function: G Zi () s +1 ≈ sT [63] gives following closed-loop transfer K Pi1K RL( 1+ sTIi 1) 2 3 ( 1+ sTIi ) + s TIi TRL + s TIi iTRL = (3. 27) K Pi1K RL 1 1 1τ Σ For the Eq. (3.27) the proportional gain and integral time constant of the PI current controller can be calculated: K T T RL Pi1 = (3. 28) iKRL 4τ 2τ Σ Ii1 = Σi (3. 29) which, substituted in Eq. (3.26), yields open loop transfer function of the form: 49
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POLITECHNIKA WARSZAWSKA WARSAW UNIV
Page 3 and 4: Acknowledgements The work presented
Page 5 and 6: Contents 4.2.2. Energy of the DC-li
Page 7 and 8: Chapter 1 1. Introduction 1.1. AC/D
Page 9 and 10: 1. Introduction Tab. 1. 1. Current
Page 11 and 12: 1. Introduction DC-link voltage to
Page 13 and 14: 1. Introduction then nominal speed
Page 15 and 16: 1. Introduction [69]. From that tim
Page 17 and 18: Chapter 2 2. Voltage Source Convert
Page 19 and 20: 2. Voltage Source Converters - VSC
Page 39 and 40: Chapter 3 3. Vector Control Methods
Page 41 and 42: 3. Vector Control Methods of AC/DC/
Page 53: 3. Vector Control Methods of AC/DC/
Page 75 and 76: Chapter 4 4. Direct Power and Torqu
Page 77 and 78: 4. Direct Power and Torque Control
Page 99 and 100: Chapter 5 5. Passive Components Des
Page 101 and 102: 5. Passive Components Design 5.2.2.
Page 103 and 104: 5. Passive Components Design a) b)
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5. Passive Components Design C T
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5. Passive Components Design Theref
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5. Passive Components Design motor
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Chapter 6 6. Simulation an Experime
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6. Simulation and Experimental Resu
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Chapter 7 7. Summary and Conclusion
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7. Summary and Conclusion • easy
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References [18] G. Buja, M. P. Kazm
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References [58] J. G. Kassakian, M.
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References [96] H. Mao, D. Boroyevi
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References [133] A. Tripathi, A. M.
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References [167] M. Jasiński, D.
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Symbols Employed I L - I LA I r - r
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Symbols Employed U pA ,U pB , U pC
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A. Appendices A.1. Space vector in
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Appendices In the special condition
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Appendices A.2. Coordinate Transfor
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Appendices S 3 UI 2 m s * * = = - a
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Appendices Tab. A. 4. 3. Date of th
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Appendices LINE L1 L C F Fig. A. 4.
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Appendices Tab. A. 4. 6. Data of th
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