Space vector PWM

Space Vector Pulse Width Modulation and implementation in Arduino.

1. Full Scale Converter for Synchronous Wind Turbine Generators Space Vector PWM Students: Aaron Ponder, Long Pham Mar. 2014 Class REE547: Electric Power Conversion

2. 3/20/2014 2 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

3. 3/20/2014 3 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

4. 3/20/2014 4 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

5. 3/20/2014 5 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

6. 3/20/2014 6 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

7. 3/20/2014 7 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 C ontrol the torque output of the generator, we need to create a smoothly rotating vector at any angle Intuitive Approach

8. 3/20/2014 8 By switching between two adjacent vectors quickly, the generator will see an average vector in-between F ilter 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  

11. Center Aligned PWM Edge aligned PWM Center aligned PWM

12. Center aligned PWM - Experiment

13. How to create a sine wave using PWM  

14. Space Vector PWM

15. Generate SVPWM in Arduino

16. Results of Lab 18 3/20/2014

17. 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.

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