Two leg three-phase inverters (FSTPIs) have been proposed to be used in low-power; low-cost applications because of the reduced number of semiconductor devices, and space vector pulse width modulation (SVPWM) techniques have also been introduced to control FSTPIs. However, high-performance controllers are needed to implement complicated SVPWM algorithms, which limit their low-cost applications. To simplify algorithms and reduce the cost of implementation, an equivalent scalar method for SVPWM of FSTPIs is proposed. SVPWM for FSTPIs is actually a sine PWM by modulating two sine waves of 600 phase difference with a triangle wave, but in this method third harmonics doesn’t eliminated. So as to eliminate the third harmonics we have to compose a high frequency sine wave to on existing sine waves. So such a special sine PWM can be used to control FSTPIs. The Mathematical and simulation results demonstrate the validity of the proposed method.
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1. DIFFERENT PWM CONTROLLED BASED FSTPI FED IM DRIVE PRESENTED By SUDHAKAR AKKI Reg.No:1610910044 UNDER THE GUIDANCE OF Mr. NALINKANT MOHANTY ASST.PROF( Sr.G )
43. (a) Timing of gate pulse of space vector PWM (b) Timing of gate pulse of carrier–based PWM In sector 2: π≤α≤2π V t is the instantaneous carrier signal .
49. Comparison of Different PWM techniques for FSTPIs Sine PWM SV PWM Scalar PWM Carrier PWM Calculation Burden Low Very High Medium Low THD 20.08% 1.86% 14.79% 4.07% Output Voltage Normal Normal Maximum Normal DC-link voltage ripple Resolved Switching loss high low low high
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51. BIBLIOGRAPHY Journals [1]. “Adaptive Carrier-based PWM for a Three-Phase Inverter under DC-link Voltage Ripple Conditions” Tuyen D. Nguyen*, Hong-Hee Lee† and Hoang M. Nguyen* Journal of Electrical Engineering & Technology Vol. 5, No. 2, pp. 290~298, 2010 [2]. Jae Hyeong Seo; Chang Ho Choi; Dong Seok Hyun, “A New Simplified space-Vector PWM Method for Three-Level Inverters”, IEEE Transactions on Power Electronics, Volume 16, Issue 4, Jul 2010, Pages 545 - 550 [3]. “the adaptive space vector pwm for four switch three phase inverter fed induction motor with dc – link voltage imbalance” by Hong Hee Lee*, Phan Quoc Dzung**, Le Dinh Khoa**, Le Minh Phuong**, Huynh Tan Thanh***School of Electrical Engineering, University of Ulsan Ulsan, Korea. [4]. Hind Djeghloud and Hocine Benalla, “Space Vector Pulse Width Modulation Applied to The Three-Level Voltage Inverter”, 5th International Conference on Technology and Automation ICTA’05, Thessaloniki, Greece, Oct 2010. Books [5]. P.S.Bimbhra, “Power Electronics”, Khanna publications. [6]. Muhammad H.Rashid “Power Electronics Circuits, devices, and Applications”, Prentice-Hall of India Private Limited, Third Edition, 2004. Thesis References [7]. Jin-woo Jung, “Space Vector PWM Inverter”, The Ohio State University, February, 2008. Website references [8]. www.ieeexplore.com
SVM treats the inverter as a single unit. Can be represented in a two dimensional space. There are 4 possible states for the inverter.
4 active vectors occupy 4 vertices of the (Parallelogram)Rhombus If phase voltages are sinusoidal, the locus of Vs is a circular
Switching losses are increased Amplitude of higher order harmonics are increased The fundamental component of output voltage is less PWM method is unable to make full use of the inverters supply voltage and asymmetrical nature of switching characteristics , produce the high harmonic distortion in the supply.