A Resonant Integrator Based PLL and AC Current Controller for Single Phase Grid Connected PWM-VSI

Grid connected PWM-VSIs are being increasingly used for applications such as Distributed Generation (DG), power quality, UPS etc. Appropriate control strategies for grid synchronisation and line current regulation are required to establish such a grid interconnection and power transfer. Control of three phase VSIs is widely reported in iterature. Conventionally, dq control in Synchronous Reference Frame(SRF) is employed for both PLL and line current control where PI-controllers are used to track the DC references. Single phase systems do not have defined direct (d) and quadrature (q) axis components that are required for SRF transformation. Thus, references are AC in nature and hence usage of PI controllers cannot yield zero steady state errors. Resonant controllers have the ability to track AC references accurately. In this work, a resonant controller based single phase PLL and current control technique are being employed for tracking grid frequency and the AC current reference respectively. A single phase full bridge converter is being operated as a STATCOM for performance evaluation of the control scheme.

A current error space vector based hysteresis controller with constant switching frequency and simple online boundary computation for VSI fed IM drive

This paper proposes a simple current error space vector based hysteresis controller for two-level inverter fed Induction Motor (IM) drives. This proposed hysteresis controller retains all advantages of conventional current error space vector based hysteresis controllers like fast dynamic response, simple to implement, adjacent voltage vector switching etc. The additional advantage of this proposed hysteresis controller is that it gives a phase voltage frequency spectrum exactly similar to that of a constant switching frequency space vector pulse width modulated (SVPWM) inverter. In this proposed hysteresis controller the boundary is computed online using estimated stator voltages along alpha and beta axes thus completely eliminating look up tables used for obtaining parabolic hysteresis boundary proposed in. The estimation of stator voltage is carried out using current errors along alpha and beta axes and steady state model of induction motor. The proposed scheme is simple and capable of taking inverter upto six step mode operation, if demanded by drive system. The proposed hysteresis controller based inverter fed drive scheme is simulated extensively using SIMULINK toolbox of MATLAB for steady state and transient performance. The experimental verification for steady state performance of the proposed scheme is carried out on a 3.7kW IM.

A Novel VSI- and CSI-Fed Dual Stator Induction Motor Drive Topology for Medium-Voltage Drive Applications

A new configuration is proposed for high-power induction motor drives. The induction machine is provided with two three-phase stator windings with their axes in line. One winding is designed for higher voltage and is meant to handle the main (active) power. The second winding is designed for lower voltage and is meant to carry the excitation (reactive) power. The excitation winding is powered by an insulated-gate-bipolar-transistor-based voltage source inverter with an output filter. The power winding is fed by a load-commutated current source inverter. The commutation of thyristors in the load-commutated inverter (LCI) is achieved by injecting the required leading reactive power from the excitation inverter. The MMF harmonics due to the LCI current are also cancelled out by injecting a suitable compensating component from the excitation inverter, so that the electromagnetic torque of the machine is smooth. Results from a prototype drive are presented to demonstrate the concept.

Hybrid LCI/VSI Power Circuit-A Universal High-Power Converter Solution for Wound Field Synchronous Motor Drives

Load commutated inverter (LCI)-fed wound field synchronous motor drives are used for medium-voltage high-power drive applications. This drive suffers from drawbacks such as complex starting procedure, sixth harmonic torque pulsations, quasi square wave motor current, notches in the terminal voltages, etc. In this paper, a hybrid converter circuit, consisting of an LCI and a voltage source inverter (VSI), is proposed, which can be a universal high-power converter solution for wound field synchronous motor drives. The proposed circuit, with the addition of a current-controlled VSI, overcomes nearly all of the shortcomings present in the conventional LCI-based system besides providing many additional advantages. In the proposed drive, the motor voltage and current are always sinusoidal even with the LCI switching at the fundamental frequency. The performance of the drive is demonstrated with detailed experimental waveforms from a 15.8-hp salient pole wound field synchronous machine. Finally, a brief description of the control scheme used for the proposed circuit is given.

A Novel VSI- and CSI-Fed Active-Reactive Induction Motor Drive with Sinusoidal Voltages and Currents

Till date load-commutated inverter (LCI)-fed synchronous motor drive configuration is popular in high power applications (>10 MW). The leading power factor operation of synchronous motor by excitation control offers this simple and rugged drive structure. On the contrary, LCI-fed induction motor drive is absent as it always draws lagging power factor current. Therefore, complicated commutation circuit is required to switch off thyristors for a current source inverter (CSI)-driven induction motor. It poses the major hindrance to scale up the power rating of CSI-fed induction motor drive. Anew power topology for LCI-fed induction motor drive for medium-voltage drive application is proposed. A new induction machine (active-reactive induction machine) with two sets of three-phase winding is introduced as a drive motor. The proposed power configuration ensures sinusoidal voltage and current at the motor terminals. The total drive power is shared among a thyristor-based LCI, an insulated gate bipolar transistor (IGBT)-based two-level voltage source inverter (VSI), and a three-level VSI. The benefits of SCRs and IGBTs are explored in the proposed drive. Experimental results from a prototype drive verify the basic concepts of the drive.

Online Computation of Hysteresis Boundary for Constant Switching Frequency Current-Error Space-Vector-Based Hysteresis Controller for VSI-Fed IM Drives

This paper proposes a current-error space-vector-based hysteresis controller with online computation of boundary for two-level inverter-fed induction motor (IM) drives. The proposed hysteresis controller has got all advantages of conventional current-error space-vector-based hysteresis controllers like quick transient response, simplicity, adjacent voltage vector switching, etc. Major advantage of the proposed controller-based voltage-source-inverters-fed drive is that phase voltage frequency spectrum produced is exactly similar to that of a constant switching frequency space-vector pulsewidth modulated (SVPWM) inverter. In this proposed hysteresis controller, stator voltages along alpha- and beta-axes are estimated during zero and active voltage vector periods using current errors along alpha- and beta-axes and steady-state model of IM. Online computation of hysteresis boundary is carried out using estimated stator voltages in the proposed hysteresis controller. The proposed scheme is simple and capable of taking inverter upto six-step-mode operation, if demanded by drive system. The proposed hysteresis-controller-based inverter-fed drive scheme is experimentally verified. The steady state and transient performance of the proposed scheme is extensively tested. The experimental results are giving constant frequency spectrum for phase voltage similar to that of constant frequency SVPWM inverter-fed drive.

A 5th and 7th order harmonic suppression scheme using capacitive filtering for 2-level VSI fed IM drive

In this paper, a 5th and 7th harmonic suppression technique for a 2-level VSI fed IM drive, by using capacitive filtering is proposed. A capacitor fed 2-level inverter is used on an open-end winding induction motor to suppress all 5th and 7th order harmonics. A PWM scheme that maintains the capacitor voltage, while suppressing the harmonics is also proposed. The proposed scheme is valid for the entire modulation range, including overmodulation and six-step mode of operation of the main inverter.

A controller design method for 3 phase 4 wire grid connected VSI with LCL filter

Closed loop control of a grid connected VSI requires line current control and dc bus voltage control. The closed loop system comprising PR current controller and grid connected VSI with LCL filter is a higher order system. Closed loop control gain expressions are therefore difficult to obtain directly for such systems. In this work a simplified approach has been adopted to find current and voltage controller gain expressions for a 3 phase 4 wire grid connected VSI with LCL filter. The closed loop system considered here utilises PR current controller in natural reference frame and PI controller for dc bus voltage control. Asymptotic frequency response plot and gain bandwidth requirements of the system have been used for current control and voltage controller design. A simplified lower order model, derived for closed loop current control, is used for the dc bus voltage controller design. The adopted design method has been verified through experiments by comparison of the time domain response.

Urochnyi a polozhenii a na vsi e voobshche raboty, proizvodi a shchii a si a pri kri e posti a kh, grazhdanskikh zdanii a kh i gidrotekhnicheskikh sooruzhenii a kh.

Mode of access: Internet.

Tak govoril Zaratustra; kniga dli︠a︡ vsi︠e︡kh i ni dli︠a︡ kogo.

Translation of his Also sprach Zarathustra.

Dissertazione di polizia medica sul Pentateuco in riguardo alle leggi spettanti alla grauidanza, al parto, puerperio, all'educazione della fanciullezza, ed ai patemi di animo con molte riflessioni filosofiche sui rabbinici commenti, ed vsi ebraici in tale materia /

Mode of access: Internet.

Nastolʹnyĭ slovarʹ dli︠a︡ spravok po vsi︠e︡m otrasli︠a︡m znanīi︠a︡. (Spravochnyĭ ėnt︠s︡iklopedicheskīĭ leksikon) v III tomakh.

Vol. 3, "Sostavlennyĭ pod redakt︠s︡ěi︠u︡ V.P. Zotova i F. Tolli︠a︡."

Malenʹkīĭ russkīĭ: Posobīe dli︠a︡ dalʹni︠e︡ĭshago usovershenstvovanīi︠a︡ v russkom i︠a︡zyki︠e︡ dli︠a︡ lit︠s︡, zhelai︠u︡shchikh svobodno vladi︠e︡tʹ zhivoi︠u︡ razgovornoi︠u︡ ri︠e︡chʹi︠u︡ vo vsi︠e︡kh sluchai︠a︡kh obikhodnoĭ zhizni ... S planom S.-Peterburga.

Added title page in German, French, English, Italian and Spanish.

Bolʹshai︠a︡ ėnt︠s︡iklopedīi︠a︡ : slovarʹ obshchedostupnykh svi︠e︡di︠e︡nīĭ po vsi︠e︡m otrasli︠a︡m znanīi︠a︡ /

t. 1. A-Arbos.--t. 2. Arbua de Zhi︠u︡bėnvilʹ-Bellingsgauzen.--t. 3. Belling-Bugulʹnik.--t. 4. Buguruslanskīĭ ui︠e︡zd-Vizantīĭskoe pravo.--t. 5. Vizantīi︠a︡-Gadames.--t. 6. Gadanīe-Glazchatka.--t. 7. Glaz-Gi︠u︡go.--t. 8. Gi︠u︡gs-Dukhovenstvo.--t. 9. Dukhovenstvo-Idskoe pole.--t. 10. Idumėi︠a︡-Kitchener.--t. 11. Kity-Landana.--t. 12. Landau-Melamed.--t. 13. Melanezīĭt︠s︡y-Nerchinskīĭ zavod.--t. 14. Nerchinskīĭ okrug-Pench.--t. 15. Penʹka-Pulʹ.--t. 16. Pulʹ-Salʹ.--t. 17. Salʹvador-Statistika.--t. 18. Statistika-Undozero.--t. 19. Undolʹskīĭ-Chakhary.--t. 20. Chakhotka legkikh-V.--t. 21. (Dopolnitelʹnyĭ) Aanrud-Menger.--t. 22. (Dopolnitelʹnyĭ) Mendelʹson-Ḟrazibul.

Pami︠a︡tnik Vostochnoĭ voĭny, 1877-1878 gg. : zakli︠u︡chai︠u︡shchīĭ v sebi︠e︡ v alfavitnom pori︠a︡dki︠e︡ bīograficheskīe ocherki vsi︠e︡kh otlichivshikhsi︠a︡, ubitykh, ranenykh i kontuzhennykh generalov, shtab i ober ofit︠s︡erov, doktorov, sanitarov, sester miloserdīi︠a︡ i otlichivshikhsi︠a︡ ri︠a︡dovykh /

Mode of access: Internet.