485

ϕ ⋅

⋅

⋅

=

cos

I

U3 P

Load

Load ,LL

el

The peak output voltageof the inverter is:

Load ,LL

Load

U

3

2

Uˆ

⋅

=

and also

DC

Load

Um

2

1 Uˆ

⋅ ⋅ =

m is the modulation factor. Thus, the RMS value of the load voltage U

LL,Load

can be

defined as:

DC

Load ,LL

Um

2 2

3

U

⋅ ⋅

⋅

=

For the power P

DC

of the DC-bus the following applies, considering the efficiency

η

Inv

of

the output inverter:

Inv

el

DC

P P

η

=

For theDC-bus current I

DC

this results in

Load

Inv

DC

Inv

Load

Load ,LL

DC DC

I

cos m

2 2

3

I

cos

U3

I U

⋅

η

ϕ ⋅

⋅

⋅

= ⇒

η

ϕ ⋅

⋅

⋅

= ⋅

or when the equations of the input rectifier are inserted

Load

Inv

Grid ,LL

Load ,LL

DC

I

U

cos

U

2 3

3

I

⋅

η⋅

ϕ ⋅

⋅

⋅

⋅π

=

1. P.F. Brosch, "Frequenzumrichter: Prinzip, Aufbau und Einsatz ", Verlag Moderne

Industrie, 4

th

Edition 2000

2. Fraunhofer IISB, "ParasitäreBauelemente undOszillationen", peak-Seminar 2004

3. B. Backlund, M. Rahimo, S. Klaka, J. Siefken, "Topologies, voltage ratings and

state of the art high power semiconductor devices for medium voltage wind energy

conversion", PEMWA 2009

4. Cornell Dubilier, "Aluminium Electrolytic Capacitors", Cornell Dubilier Application

Note 2006

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