space vector PWM for 2 leg inverter
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Transcript of space vector PWM for 2 leg inverter
SPACE VECTOR MODULATION
FOR TWO LEG INVERTERSPRESENTED
By
SUDHAKAR AKKISUDHAKAR AKKI
Reg.No:1610910044
UNDER THE GUIDANCE OF
Mr. NALINKANT MOHANTYASST.PROF( Sr.G )
INTRODUCTION
• Semiconductor switches mainly determine the overall price of power
converters.
• The main objective of this project is to prove 2leg inverters are the best
option for low power applications for getting the good performance.
• Two leg inverter produces the square wave or quasi-square wave. but low
power applications allow the two leg inverter output.
• In many industrial applications, it is often required to vary the output
voltage of the inverter due to the following reasons
To cope with the dc I/p voltage.
To regulate the voltage of inverters
To satisfy the constant voltage & frequency for control requirement.
Pulse-Width Modulated For VSI
Disadvantages of PWM semiconductor devices must have low turn-on and turn-off times. so, they are very expansive
Reduction of available voltage
Increase of switching losses due to high PWM frequency
Control of inverter output voltage with out any additional components
Reduction of lower harmonics
The most common PWM approach is sinusoidal PWM. In this method a
triangular wave is compared to a sinusoidal wave of the desired frequency and the
relative levels of the two waves is used to control the switching of devices in each
phase leg of the inverter.
Objective of PWM
Space vector modulation
• In sinusoidal PWM, the inverter can be thought of as three separate
push-pull driver stages, which create each phase waveform
independently.
• SVM, however treats the inverter as a single unit
• The space vector method is a d,q model PWM approach
Modulation index is high
SVM produces 15% higher then the sinusoidal PWM in output voltages
Simple, inherently digital calculation of the switching times.
SVPWM has been gaining more attention in the industry.
Block diagram of the project
Principle of Space Vector PWM
Treats the sinusoidal voltage as a constant amplitude vector rotating
at constant frequency
This PWM technique approximates the reference voltage Vref by a combination
of the Four switching patterns (V1 to V4)
Coordinate Transformation (abc reference frame to the stationary d-q frame)
: A three-phase voltage vector is transformed into a vector in the stationary d-q coordinate
frame which represents the spatial vector sum of the three-phase voltage
The vectors (V1 to V4) divide the plane into Four sectors (each sector: 90 degrees)
Vref is generated by two adjacent non-zero vectors and two zero vectors
Comparison of Sine PWM and Space Vector PWM
Space Vector PWM generates less harmonic distortion
in the output voltage or currents in comparison with sine PWM
Space Vector PWM provides more efficient use of supply voltage
in comparison with sine PWM
Voltage Utilization: Space Vector PWM = 2/3 times of Sine PWM
Realization of Space Vector PWM
Step 1. Determine Vd, Vq, Vref, and angle ()
Step 2. Determine time duration T1, T2, T0
Step 3. Determine the switching time of each transistor (S1 to S4)
SPACE VECTOR PWM FOR 2-LEG INVERTER
Space vectors representation
Magnitude, angle& sector representation
Alpha
Beta
Determine time duration T1, T2, T0
1
1
2
2
T cos
T sin
VsTsV
VsTsV
Determine the switching time of each transistor (S1 to S4)
Switching times of each sector
Simulation circuit of 2 leg inverter by SVM
Sectors for 2-leg inverter
Angle
Sectors
Sectors for 3-leg inverter
Switching time duration
Switching time duration for two leg inverter
Connotative Modulation Functions for 2leg
Connotative Modulation Functions for 3 leg
Phase voltages of 3-leg inverters
Line Voltages
Switching time duration for two leg inverter with un-equal vector magnitudes….
FFT analysis
CONCLUSION
• In this dissertation work, it is shown that two-leg inverters are the best option for high performance low power applications. It can be resolved by comparing the no of semiconductor switches usage in 2-leg and 3-leg inverters and moreover two leg inverters allow the asymmetrical voltages
• To enable this, space vector pulse width modulation (SVPWM) technique for two-leg and three-leg inverters is presented.
BIBLIOGRAPHY
• [1]. 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.
• [2]. Jin-woo Jung, “Space Vector PWM Inverter”, The Ohio State University, February, 2008.
• [3]. 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
• [4]. Muhammad H.Rashid “Power Electronics Circuits, devices, and Applications”, Prentice-Hall of India Private Limited, Third Edition, 2004.
• [5]. “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.
• [6]. P.S.Bimbhra, “Power Electronics”, Khanna publications.• [7]. Overview of MATLAB Simulink Http://www.mathworks.com/products/simulink/description/overview.shtml
THANK YOU