This document discusses space vector pulse width modulation (SVPWM) for controlling a three-phase inverter that supplies power from a DC source to drive electric machines like wind turbine generators. It provides a brief history and introduction to SVPWM, explaining that it was developed in the 1980s and represents voltage vectors in three-phase space. The document outlines benefits like higher efficiency, voltage control, and reduced losses compared to sinusoidal PWM. It describes implementing SVPWM using an Arduino to generate PWM signals that create an average output voltage through rapid switching between active voltage vectors.

1. Full Scale Converter for Synchronous
Wind Turbine GeneratorsSpace Vector PWM
Students: Aaron Ponder, Long Pham
Mar. 2014
CLASS REE547: ELECTRIC POWER CONVERSION

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• Early 1960’s Kirnnich, Heinrick and Bowes first developed PWM [1]
• 1964 Carrier based techniques developed first, followed by SPWM by
Schonung and Stemmler [2]
• Not until mid-1980’s was SVPWM introduced [3]
Introduction and history

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• 3 phase variables are expressed in space vectors
• Space Vectors
• Main objective: approximation of reference voltage vector utilizing eight
switching patterns [5]
• Each desired voltage vector can be simulated by an averaging effect
between two adjacent active vectors and a zero vector.
• 3 phase inverter
Briefing

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• Higher DC bus efficiency
• Voltage magnitude control
• Low power losses
• Variable frequency control
• Other advantages are a wide linear modulation range, low switching
loss, ease of implementation, and reduce computational complexity due
to fewer sin functions
• advantages under unbalanced motor operation conditions
Benefits

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• SVPWM maximum peak fundamental magnitude of 90.6% of
inverter capacity is 15.5% over SPWM [6]
• 1991, Holtz proposed over-modulation based SVPWM, further
improving the DC bus voltage usage to the levels of six step
waves [7] [8].
Benefits elaboration

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• Often used to supply 3-phase AC voltage from DC source to
drive machines
• Modulation strategy plays an important role in the
minimization of harmonics and the switching losses
Use

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• Six of the eight states result in
voltage applied to the generator
windings with two states resulting
in zero voltage as seen in the figure
below
• Control the torque output of the
generator, we need to create a
smoothly rotating vector at any
angle
Intuitive Approach

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• By switching between two adjacent vectors quickly, the generator will
see an average vector in-between
• Filter between the inverter and the generator will filter out the high
frequency effect caused by the switching
Intuitive Approach Cont.

9. Implement SVPWM in Arduino

10. By changing the amount of time outputting 5V and 0V, we create an average voltage
output
PWM – How to create any voltage output very efficiently
𝑉𝑜𝑢𝑡 = (𝐷𝑢𝑡𝑦 𝐶𝑦𝑐𝑙𝑒) ∗ 𝑉𝑖𝑛

11. Center Aligned PWM
Edge aligned PWM Center aligned PWM

12. Center aligned PWM - Experiment

13. How to create a sine wave using PWM 𝑉𝑜𝑢𝑡 = (𝐷𝑢𝑡𝑦 𝐶𝑦𝑐𝑙𝑒) ∗ 𝑉𝑖𝑛

14. Space Vector PWM

15. Generate SVPWM in Arduino

18. Results of Lab
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3/25/2014

19. Benefit of SVPWM – Lower switching loss
Mosfets switch 6 times ~ output switch 1 time. Mosfets switch 6 times ~ output switch 2 time.
If we have to output a same frequency, Mosfets in SVPWM scheme have to switch ½ less than normal SPWM.

20. Full Scale Converter for Synchronous
Wind Turbine Generators
Thank you!