Consider a light dimmer circuit that is controlled using a single SCR with a firing angle...

 

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Consider a light dimmer circuit that is controlled using a single SCR with a firing angle a. Assume a 120V 60Hz purely sinusoidal voltage at the source and a 100 resistance for the lightbulb. Model the system in MATLAB/Simulink, PSCAD, or any other software of choice and plot the relevant variables for a firing angle of 45°. These include the source voltage, load voltage (across the lightbulb) and load current (through the lightbulb). Make sure that the plots are sufficiently zoomed in so as to clearly demonstrate the relevant dynamics. Plot the individual harmonics of the load current (2nd through 13th) in percentage values (as a bar graph) and specify as the total THD₁. Next, add an inductance of 0.1 H to the load (in series with the 100 resistor). How does the results above change? Present your results and discuss. Finally, add a second anti-parallel SCR, forming a back-to-back SCR configuration (see below) and redo the exercise (for the resistive load as well as the inductive load). Present your results and analyze the findings. E Consider a light dimmer circuit that is controlled using a single SCR with a firing angle a. Assume a 120V 60Hz purely sinusoidal voltage at the source and a 100 resistance for the lightbulb. Model the system in MATLAB/Simulink, PSCAD, or any other software of choice and plot the relevant variables for a firing angle of 45°. These include the source voltage, load voltage (across the lightbulb) and load current (through the lightbulb). Make sure that the plots are sufficiently zoomed in so as to clearly demonstrate the relevant dynamics. Plot the individual harmonics of the load current (2nd through 13th) in percentage values (as a bar graph) and specify as the total THD₁. Next, add an inductance of 0.1 H to the load (in series with the 100 resistor). How does the results above change? Present your results and discuss. Finally, add a second anti-parallel SCR, forming a back-to-back SCR configuration (see below) and redo the exercise (for the resistive load as well as the inductive load). Present your results and analyze the findings. E

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