Thyristor soft-starter in Matlab

In summary: Additionally, it may be necessary to change the parameters of the thyristor to ensure it can handle the specific voltage and current requirements. In summary, to control the firing angle of the thyristors in a soft starter using Matlab, the PWM technique can be used and the parameters of the thyristor may need to be adjusted for the given voltage and current values.
  • #1
greg997
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2
Can anybody help me with this, please.

I am supposed to design a soft starter to reduce inrush current from grid to the 3 phase induction machine.
My understanding is that initially the high inrush current is blocked by thyristor and after a period of time the normal current is allowed to flow through by-pass. And that soft starter consists of a pair of thyristors per phase. In total 6 of them.
The problem I have is how to control in Matlab the firing angle of those thyristors.
I attached a circuit diagram, where for clarity other components and other thyristors were removed. The voltage is 400 V and the inrush current is 20, but normal current is 6 or 7 A.
Do I have to change the paramters of the thyristor to operate with those voltages and current?

I will appreciate any help.
 

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  • #2
Thank you.The way to control the firing angle of the thyristors in Matlab is by using the PWM (Pulse-Width Modulation) technique. In this method, the voltage applied to the thyristor is turned on and off at regular intervals, with the duty cycle (the percentage of time that the voltage is on) being varied to control the average current flow through the thyristor. The firing angle of the thyristor can then be adjusted by changing the duty cycle of the PWM signal.
 

1. What is a thyristor soft-starter and how does it work?

A thyristor soft-starter is an electronic device used to control the starting and stopping of electric motors. It uses thyristors, which are semiconductor devices, to gradually increase the voltage to the motor, instead of providing full voltage immediately. This reduces the stress on the motor and helps prolong its lifespan.

2. Why is Matlab commonly used for designing thyristor soft-starters?

Matlab is commonly used for designing thyristor soft-starters because it is a powerful and versatile software tool that allows for simulation, analysis, and optimization of complex electrical systems. It also has built-in functions and libraries specifically for designing power electronics, making it a popular choice for engineers.

3. Can Matlab be used to simulate the performance of a thyristor soft-starter?

Yes, Matlab can be used to simulate the performance of a thyristor soft-starter. It has various simulation tools, such as Simulink, that allow for the creation and analysis of models of electrical systems. This can help engineers predict the performance of a thyristor soft-starter before it is built, saving time and resources.

4. What are the key parameters to consider when designing a thyristor soft-starter in Matlab?

The key parameters to consider when designing a thyristor soft-starter in Matlab include the motor's power rating, starting torque and current, acceleration time, and the type of load the motor will be driving. Other factors such as the type and rating of the thyristors used, as well as the control strategy, also need to be taken into account.

5. How can Matlab help in optimizing the design of a thyristor soft-starter?

Matlab has optimization tools that can be used to find the best values for the design parameters of a thyristor soft-starter. These tools can help engineers find the most efficient and cost-effective solution for their specific application. Additionally, Matlab's simulation capabilities can also be used to test and fine-tune the design, further optimizing its performance.

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