LAB-02 ECA 2 Introduction to LTSpice PDF

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Electrical Circuit Analysis II EEE222

Lab Report 2

Name

Registration Number

Class

Instructor’s Name

Mohammad Shuja ur Rehman Khan

FA19-BEE-106

3C

Dr. Amir Rasheed Chaudhary

Lab # 02 Introduction to LTSpice Objective: Introduction to LTSpice using Simulation of Natural and Step Response of Parallel RLC circuits.

Pre Lab: Solve the parallel RLC circuit for the following conditions. Bring the solution and final result with you in the lab. 1. R = 2K, L = 250mH and C = 10nF. The initial current in the inductor at t=0 is -4A. The initial voltage across the capacitor is zero. Find the expression of v (t) for t>0.

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2. R = 62.5 ohm, L = 10mH and C=1uF. The initial current in the inductor at t=0 is 80mA. The initial voltage across the capacitor is 10V. Find the expression of v (t) for t>0.

3. R = 4K, C = 0.125uF, L = 8H. The initial current in the inductor at t=0 is -12.25mA. The initial voltage across the capacitor is 0V. Find the expression of v(t) for t>0.

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Section -1 In Lab Tasks In Lab: OBJECTIVES 1. Introduction to the DC bias point and Transient Analysis of LTSpice. 2. Understanding the Natural and Step response of RLC circuits using simulations. 3. Understanding the concepts of overshoot, settling time and rise time using simulations.

Task – 1 (Simulating Bias Point) Current Direction:

Simulation

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Task-2 (Transient Analysis) For R = 200Ω :-

For R = 312.5Ω:-

Observations for Task 2: 𝜶𝟐

𝛚𝟐

Type of response

Settling Time

1 x 10

2.06 x 10

Over Damped

120ms

1 x 10

7.1 x 10

Under Damped

150ms

8

8

8

7

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Task -3 (Step Response) For R = 400 :-

For R = 625 :-

For R = 500:-

Observations: Resista esistance nce

wo2

α2

400 Ω

16x10^9

27x10

625 Ω

16x10^9 124x10

500 Ω

16x10^9

Type of response 8

8

15x10

8

Over damped Over damped Critically Damped

Overshoot Rise Time

Settling Time

24mA

324μs

0-360 μs

26mA

90μs

0-100μs

24mA

207μs

0-230μs

------------------------------------------------------------------Section II - (Design Problem) 1. Design the value of R i.e. the rise time of the voltage vc(t) is less than 400usec. What is the type of response? What is the value of R? What is the value of overshoot?

𝛂𝟐 =2.25 x 10^6 𝒘𝒐𝟐 = 2.5 x 10^7 and Type of response: Under Damped. Value of R: 300 Ω Value of Over-shoot: 18 V.

the va there is n 2. Now re-d re-de esign the valu lu lue e of R i.e. there no o ov over-shoo er-shoo er-shoott th this is tim time. e. Wha Whatt is th the e ttype ype o off re respon spon sponsse? W Wh hat is tth he val valu ue of R R?? And w wh hat is th the e val valu ue of ris rise e tim time? e?

𝒘𝒐𝟐 = 2.5 x 10^7 𝛂𝟐 = 2.425 x 10^7 Type of response: Under Damped. Value of R: 985 Ω Value of Over-shoot: 0V Rise-Time: 762.1 𝜇s. ------------------------------------------------------------------------------------------------

Post Lab: Answer the following Write a short note on the relative advantages and disadvantages of the over damped, under damped and critically damped responses. Which response is suitable for what type of application?

Under damped: An underdamped system yields an exponentially decreasing sinusoidal output in response to a step input, e.g: A Simple pendulum.

Critically damped: A critically damped system the minimum amount of damping that will yield a non-oscillatory output in response to a step input, e.g: The automobile shock absorber. The advantage of critical damping is that the vibratory system does not come to rest the vibratory body comes to rest in smallest possible time the amplitude of vibration is maximum the vibratory system is unstable

Over damped: An overdamped system also yields a non-oscillatory output in response to a step input , but has more damping than necessary to achieve the non-oscillatory output, e.g: Door closers.

Note: An underdamped car will tend to ride a little smoother on small bumps but will have more large vibrations apparent. An overdamped car will tend to feel more planted over big jounces, but will be rougher on smaller bumps

Critical Analysis / Conclusion: The given lab tasks have been performed and implemented using LTSpice. This experiment showed some new techniques of LTSPICE, also about some damping systems and some basic definitions like settling time, Rising time and Over-shoot. Different behaviour of the graphs according to the variation in resistances, has also been studied....