ABB Guide to Harmonics with AC DrivesGuide to Harmonics
with AC Variable Frequency Drives

Contents

Summary of harmonics attenuation

There are many options to attenuate harmonics either inside the drive system or externally. They all have advantages and disadvantages and all of them show cost implications. The best solution will depend on the total loading, the supply to the site and the standing distortion. In the following tables different internal actions are compared to the basic system without inductor. The harmonic content is given with 100% load. The costs are valid for small drives. For multidrive the 12-pulse solution is quite a lot cheaper.

6-pulse rectifier without inductor 

Manufacturing cost 100% Typical harmonic current components.

Fundamental 5th 7th 11th 13th 17th 19th
100% 63% 54% 10% 6,1% 6,7% 4,8%

 

6-pulse rectifier with inductor 

Manufacturing cost 120%. AC or DC choke added Typical harmonic current components.

Fundamental 5th 7th 11th 13th 17th 19th
100% 30% 12% 8,9% 5,6% 4,4% 4,1%

 

12-pulse rectifier with polygon transformer 

Manufacturing cost 200% Typical harmonic current components.

Fundamental 5th 7th 11th 13th 17th 19th
100% 11% 5,8% 6,2% 4,7% 1,7% 1,4%

 

12-pulse with double wound transformer 

Manufacturing cost 210% Typical harmonic current components.

Fundamental 5th 7th 11th 13th 17th 19th
100% 3,6% 2,6% 7,5% 5,2% 1,2% 1,3%

 

24-pulse rectifier with 2 3-winding transformers 

Manufacturing cost 250% Typical harmonic current components.

Fundamental 5th 7th 11th 13th 17th 19th
100% 4,0% 2,7% 1,0% 0,7% 1,4% 1,4%

 

Active IGBT rectifier

Manufacturing cost 250%. Not significant if electrical braking is anyway needed.
Typical harmonic current components.

Fundamental 5th 7th 11th 13th 17th 19th
100% 2,6% 3,4% 3,0% 0,1% 2,1% 2,2%

 

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