Top 30 industrial electronics sites: 
 
1. https://en.wikipedia.org/wiki/Variable-frequency_drive 
2. http://www.eaton.com/Eaton/ProductsServices/Electrical/ProductsandServices/AutomationandControl/AdjustableFrequencyDrives/index.htm?wtredirect=www.eaton.com/drives 
3. https://www.yaskawa.co.jp/en/product/ac 
4. https://www.ia.omron.com/products/category/motion_drives/servomotors_servo-drivers/ 
5. http://www.schneider-electric.com/b2b/en/products/product-launch/altivar-process/ 
6. http://www.deltaww.com/Products/CategoryListT1.aspx?CID=060101&amp;PID=ALL&amp;hl=en-US 
7. http://www.emersonindustrial.com/en-US/controltechniques/products/acdrives/Pages/acdrives.aspx 
8. https://dsc.lenze.de/dsc-core/index 
9. http://drives.danfoss.com/products/vlt/ 
10. http://new.abb.com/drives/low-voltage-ac 
11. http://www.hitachi-america.us/ice/inverters/ 
12. http://www.mitsubishielectric.com/fa/products/drv/inv/ 
13. http://www.ti.com/solution/motor_control_ac_induction 
14. http://www.invertekdrives.it/solutions/case-study.aspx?caseStudyID=1 
15. http://ph.parker.com/de/en/ac-drives 
16. https://www.keb.de/drives/products-drives 
17. http://www.bosch.de/en/de/our_company_1/business_sectors_and_divisions_1/electrical_drives_1/electrical-drives.html 
18. http://www.vacon.com/ro-RO/Vacon/media/Articles/what-is-a-variable-speed-ac-drive/ 
19. http://www.vesper.ru/catalog/invertors/ 
20. http://www.rockwellautomation.com/es_EC/products-technologies/overview.page? 
21. https://www.sdsdrives.com/ 
22. http://www.mielectric.com/brazil 
23. http://www.kbelectronics.com/Variable_Speed_AC_Drives_Inverters.html 
24. http://prom-electric.ru/articles/1/1/ 
25. http://old.weg.net/us/Products-Services/Drives/Variable-Speed-Drives 
26. http://www.unicous.com/products/standard-drives 
27. http://powtran.kz/assets/8.pdf 
28. http://trikueni-desain-sistem.blogspot.kr/2013/09/Prinsip-Dasar-Inverter.html 
29. http://www.energysave.kg/en/proj_2013/137/ 
30. http://www.conems.sd/index.php/services/building-automation-system-bas