Simple LCR Series Circuit

 Fig. 1 LCR Circuit

1. Drawing the circuit with LTSPICE

If you need some ground points, you add them.

In this case, we assume they aren’t needed.

2. Make a SPICE Netlist of the circuit

Click on SPICE Netlist.

3. Verify the current direction of each circuit element(R, L, C, Source etc.)

1. Choose the netlist of your Simple LCR circuit on Wasabi

2. Click [The direction of current] button.

 

3. Verify the current direction of each circuit element(R, L, C) whether the current direction is the same as iL1 on Fig.1

If some elements have  wrong current directions, you should fix them by the following steps.

1-1. With LTSPICE, you should rotate any element have  wrong current directions.

1-2. As it finished, save the file(asc) and make SPICE NetList again.

1-3. If  save the your circuit in LTSPICE, Wasabi reloads automatically the asc file of the circuit .

1-4. Please check the current direction again.

 

4. Make a model of the circuit

Click [Modeling] button to get a state space equation of your circuit

5. Export and Copy the model to other applications or Get transfer function of the circuit

For example, click on [Copy as TeX] and we can get TeX Code of this model.

So compile it with TeX, finally we can get the below equation.

   

(1)  

(2)  

(3)  

(4)  

Note:

“i_ElementName” means the voltage of ElementName.

“v_ElementName” means the voltage of ElementName.

Wasabi assumes the relationship between the high potential and the current direction as shown the below figure.

Briefly Wasabi assumes the current flows from the high potential to low potential.

Transformer 

 

M means a mutual inductance().

In general,  such as this case ( represent the number.)

1. Drawing the circuit with LTSPICE

 

Note:

E1, E2 are Voltage Dependent Voltage Source on SPICE, but Wasabi recognizes them as Transformers.

 

2. Make a SPICE Netlist of the circuit

3. Verify the current direction of each circuit element(R, L, C, Source etc.)

 Note:

E’s order must be in sequence.
(For example, E1, E2 is the correct order, and E1, E3 is the incorrect if the circuit has a single transformer.)

4. Make a model of the circuit

5. Export and Copy the model to other applications or Get transfer function of the circuit

 Note:

When you export this model to other applications, Wasabi automatically replaces E1 and E2 with L1 and L2 respectively. If L1 and L2( just inductors) exist in the same circuit,  Wasabi automatically replaces E1 and E2 with Lt1 and Lt2 respectively.

Current Source