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) Based on this signals, the state variable of the drive can be indirectly calculated or estimated what further allow to achieve the estimated (actual) rotor speed of PMSM. Two motion sensorless control schemes of DTC-SVM for PMSM drive are presented in Fig. 6.2 a) U DC Ω m _ ref Ψ s _ ref M e _ ref e Me ∆δ U s α _ ref U s β _ ref S A S B S C θ Ψ s Ψ s I s U s M e I s Ω m _ est b) U DC Ω m _ ref Ψ s _ ref M e _ ref e Ψ s e M e U sx _ ref U sy _ ref U s α _ ref U s β _ ref S A S B S C Ψ s M e θ Ψs U s I s Ω m _ est Figure 6.2. The DTC-SVM block schemes of PMSM without motion sensor: a) cascade structure and b) parallel structure. In motion sensorless PMSM drives, as shown in Fig.6.2, the position or speed transducer (see Fig. 5.52) is replaced by a speed estimation block, which generates the speed feedback signal Ω into the control systems and stator flux model. m_ est 122
Sensorless Speed Direct Torque Control with Space Vector Modulation (DTC-SVM) The problem associated with speed sensorless operation of PMSM drive sourced from VSI is listed below: • initial rotor flux detection at start up of PMSM controlled drive, • stator flux estimation without measured speed or position signal from sensor, • rotor speed estimation based on state variable of the PMSM, especially in low speed operation region. Therefore, in this Section the initial rotor position detection method of permanent magnets, as well as stator flux and rotor speed estimation techniques will be discussed. 6.2 Initial rotor detection method In a PMSM drive the detection of initial flux position is an important task. The initial position of the rotor must be detected correctly in order to initialize the flux estimation procedure. In case of wrong detection the control algorithm has incorrect information and the rotor shaft can be rotated through few second in positive or negative direction. This situation is not acceptable in any drive system. Therefore, for the stable starting of PMSM drive without the temporary reversal rotation, the initial rotor position estimation is proposed. The simplest method to achieved the initial rotor flux position is based on the following rule. For short time the stator winding is supplied by the DC voltage. It impress the DC current, which generates the magnetic field. The permanent magnet of PMSM sets accordance with this field line. This position of PM flux is used to set initial values for the stator flux estimation algorithm. This method is very simple and not complicate. However, has disadvantage that during this process the rotor can be moved in unknown direction depending on: • position of PM before initial detection procedure, • direction of DC voltage supply into the motor phase. In order to make the initial rotor flux position correct without any movement (at standstill) the following algorithms can be used in the literature [78,90,93,95,99,101] 123
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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 167 and 168: Appendices APPENDICES A1 Rotor and
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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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