Controlled Voltage Source (Three-Phase)

After the three-phase voltage signal passes through the Controlled Voltage Source (Three-Phase), the amplitude becomes root three times the original value, and the phase also changes. But according to the module description:

• Instantaneous — The output voltages, [va vb vc], are equal to the values of the input port S.

The signal input and output should be same..

Could anyone help me this question? Many thanks.

[Umar]

Hi Yunzhong,

In Simulink, the Controlled Voltage Source block is designed to model a voltage source that can be controlled based on the input signal. The discrepancy you are observing between the expected behavior and the actual behavior can be explained by understanding the different input types and configurations available in the block.

Input Types

1. Instantaneous (Default):

In this mode, the output voltages [va, vb, vc] are expected to be equal to the values of the input port S instantaneously. This means that the output should mirror the input signal without any amplitude or phase alterations.

2. Sinusoidal Magnitude and Phase Shift:

When the input type is set to sinusoidal magnitude and phase shift, the output behavior changes. The output voltages will be a sinusoidal waveform with an amplitude that is root three times the original value and a phase shift relative to the input signal.

For more information, please refer to

https://www.mathworks.com/help/sps/ref/controlledvoltagesourcethreephase.html#

Resolution:

To address the discrepancy and align the behavior with the expected output matching the input signal, you need to ensure that the input type is set to "Instantaneous." By selecting this option, the output voltages should precisely replicate the input signal without any amplitude scaling or phase shifts.Here is an example of how you can set the input type in Simulink:

% Simulink Model Configuration

model = 'YourModelName';

open_system(model);

% Accessing Controlled Voltage Source Block Parameters

block = [model, '/Controlled Voltage Source'];

open_system(block);

% Setting Input Type to Instantaneous

set_param(block, 'InputType', 'Instantaneous');

By configuring the Controlled Voltage Source block with the correct input type, you can ensure that the output voltages match the input signal as expected, providing consistency in your simulation results.

[Yunzhong]

Actually I ready set the InputType as ‘Instantaneous‘ but it cause the difference. Its strange.

[Umar]

Hi Yunzhong,

I concur with your statement.

Answer 1

[nick]

Hi Yunzhong,

I understand that you are facing an issue with the difference in the value measured by the sensor and the original value. The reason of the discrepancy is that 'Current and Voltage Sensor" block measures phase to phase voltage by default. The phase to phase voltage is square root 3 times the phase to ground voltage.

You can change the 'Voltage measurement type' from phase-to-phase to phase-to-ground voltage. You may refer the following documentation to learn more about the "Current and Voltage Sensor" block:

https://www.mathworks.com/help/sps/ref/currentandvoltagesensorthreephase.html

Hope this helps.

[Yunzhong]

Understand. Thank you so much！

[Umar]

So, it was the setting issue with Current and Voltage Sensor block which makes sense now because that will cause the amplitude to become root three times the original value, and the phase change when using controlled voltage source but glad to know that this issue is resolved.