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Three-Phase AC-DC-AC PWM Converter

version 1.3 (145 KB) by

SimPowerSystems model of a three-phase PWM VSC-based power supply.

12 Ratings



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A 50 kW, 380 V, 50 Hz load is connected to a 25 kV, 60 Hz grid through a AC-DC-AC power supply. This power supply consists of two voltage source converters, VSC1 and VSC2, connected through a DC link.

VSC1 connected on 60Hz grid is operating as a rectifier. It regulates the DC link voltage at 680 V and keeps unity power factor on AC grid. The PWM chopping frequency is 1980 Hz.

VSC2 connected on 50 Hz load is operating as an inverter. It generates a 50 Hz frequency and regulates load voltage at 380 Vrms. The PWM chopping frequency is 2000 Hz.

The electrical circuit is discretized at 2 microseconds. The sampling time of the VSC1 and VSC2 control systems is 100 microseconds.

Authors: Gilbert Sybille & Pierre Giroux, Hydro-Québec (IREQ)

Comments and Ratings (27)

Hi Patrice,
thank you for the great model.
Do you think it is possible to get a documentation of the model functionality?

Hi sir,
Can u please forward us the reference paper.
And pls can u explain mathematical calculation involved in the circuit.

Novri Andonal

is same back to back converter with bidirectional converter?

Hi Patrice,
Can you please explain how to calculate the LC filter parameters. I am referring to the connected LC filter between the inverter and the load.


thank you

basith kaja

please give notes of VSC

vidya shree

plz tell how to connect the wind system to both side of back to back converter

anjali rd

anjali rd

hai i need to connect this back to back converter to a variable speed wind system . bt it shows som error and the dc link votage is nt setting to 680



Asad Waqar

Why reference dc voltage is divided by 2 in the Uabc_ref Generation block.

Asad Waqar

Could somebody tell about the IEEE reference paper about this model?


smile mark

good ,thanks!!!i don't know how to set the Kp and Ki


Sir, can u tell me some ieee reference papers regarding this model.


zwbscg (view profile)



Ali (view profile)

Hi Patrice,
Would you please explain how to design the output LC filter? Do you have any good reference for it?


Hi Patrice
can u pls tell me how to find the rating of filter.


cr28 (view profile)

is it possible to stick s battery in there (between the two units) and make it act as a grid energy storage unit?

zoheir tir

thank you Patrice Brunelle


Arjun (view profile)

Hi Patrice,
I am working on a simulink model for a single phase inverter. I am struggling with gate control for the inverter to maintain 120V rms ac output.
Can you please provide me some references for the inverter control for single phase.


Thanks Patrice and the authors: Gilbert Sybille & Pierre Giroux, Hydro-Québec (IREQ)...

Patrice Brunelle

Hi Manu,
Please note that the DC link capacitance is C= 1500e-6 F (not 75 000e-6 F as stated in my previous response).
Calculation of the Wc/Pnom ratio is correct.

Patrice Brunelle

Hi Manu,
The size of the DC link capacitor of a VSC converter is determined by the Wc/Pnom ratio where Wc = energy stored in the capacitor bank at nominal DC link voltage (Joules) and Pnom = nominal power of the converter. This ratio is usually a fraction of a cycle, typically between 0.25 cycle and 0.75 cycle.

In our demo, C=75 000e-6 F, Vc=750 V, Pnom=50 kW

Wc/Pnom= 0.5*1500e-6*750^2 / 50e3= 0.0084 sec = ½ cycle for 60 Hz frequency

Please note that this ratio is given in the model (see comments in blue) .

In other words, it means that, with the energy stored in the capacitor, the inverter could theoretically deliver nominal power to the load during 8. 4 ms when the inverter is disconnected from the rectifier.

Manu Jain

Hi Patrice,
Can you please tell me how to size the dc-link capacitor or how to find the uF value of dc-link capacitor for such a rectifier-inverter system? If possible, let me know the reference IEEE paper or book or datasheet to calculate capacitor value.



Fixed a comment in the model.


Fixed VSC2 control: Uref and modulation index now computed as in VSC1 Control.
Transformer voltage ratio, DC bus voltage and size of capacitor bank have been changed so that modulation indexes of VSC1 and VSC2 stay close to 1.


I added a preview image of the model.

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