Unterschiede
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electrical_engineering_and_electronics_1:block06 [2025/09/29 00:40] – angelegt mexleadmin | electrical_engineering_and_electronics_1:block06 [2025/09/29 00:57] (aktuell) – mexleadmin | ||
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- | In the simulation, a measuring current $I_\Omega$ is used to determine the resistance value. ((This concept will also be used in an electrical engineering lab experiment on [[elektrotechnik_labor: | + | In the simulation, a measuring current $I_\Omega$ is used to determine the resistance value. ((This concept will also be used in an electrical engineering lab experiment on [[elektrotechnik_labor: |
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In order to understand why is this nevertheless chosen so high in the simulation, do the following: Set the measuring current for both linear sources to (more realistic) $1~\rm mA$. What do you notice? | In order to understand why is this nevertheless chosen so high in the simulation, do the following: Set the measuring current for both linear sources to (more realistic) $1~\rm mA$. What do you notice? | ||
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==== Longer exercises ==== | ==== Longer exercises ==== | ||
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- | Quick checks | ||
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- | A divider $R_1=3.3~\rm k\Omega$, $R_2=6.8~\rm k\Omega$ is fed from $U=10.0~\rm V$ and loaded by $R_{\rm L}=10.0~\rm k\Omega$. Replace the divider by its Thevenin equivalent, then compute $U_{\rm L}$ and the **loading error** relative to the ideal (no-load) divider output. | ||
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- | $R_{\rm ie}=R_1\parallel R_2=\dfrac{(3.3)(6.8)}{3.3+6.8}~\rm k\Omega=2.22~\rm k\Omega$. | ||
- | $U_{0\rm e}=\dfrac{R_2}{R_1+R_2}U=6.8/ | ||
- | $U_{\rm L}=U_{0\rm e}\dfrac{R_{\rm L}}{R_{\rm L}+R_{\rm ie}}=6.80~{\rm V}\cdot \dfrac{10.0}{12.22}=5.56~{\rm V}$. | ||
- | Ideal (no-load) output would be $6.80~\rm V$ ⇒ loading error $=1.24~\rm V$. | ||
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<panel type=" | <panel type=" | ||
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- | <panel type=" | ||
- | {{youtube>xtOPwmUgPjc}} | + | <panel type=" |
- | </ | + | Simplify the following circuits by the Norton theorem to a linear current source (circuits marked with NT) or by Thevenin theorem to a linear voltage source (marked with TT). |
- | <panel type=" | + | <imgcaption BildNr3_0 | Simplification by Norton / Thevenin theorem> </imgcaption> {{drawio>BildNr3_0.svg}} </ |
- | {{youtube>UU_RJJ6ne4I}} | + | <button size=" |
+ | To substitute the circuit in $a)$ first we determine the inner resistance. | ||
+ | Shutting down all sources leads to | ||
+ | \begin{equation*} | ||
+ | R_{\rm i}= 8~\Omega \end{equation*} | ||
- | </ | + | Next, we figure out the current in the short circuit. |
+ | In case of a short circuit, we have $2~V$ in a branch which in turn means there must be $−2~V$ on the resistor. | ||
+ | The current through that branch is | ||
+ | \begin{equation*} I_R=\frac{2~V}{8~\Omega} \end{equation*} | ||
- | <panel type=" | + | The current in question is the sum of both the other branches |
+ | \begin{equation*} I_S= I_R + 1~A \end{equation*} | ||
- | {{youtube> | + | To substitute the circuit in $b)$ first we determine the inner resistance. |
+ | Shutting down all sources leads to | ||
+ | \begin{equation*} R_{\rm i}= 4 ~\Omega \end{equation*} | ||
- | </ | + | Next, we figure out the voltage at the open circuit. |
+ | Thus we know the given current flows through the ideal current source as well as the resistor. | ||
+ | The voltage drop on the resistor is | ||
+ | \begin{equation*} R_{\rm i}= -4~\Omega \cdot 2~A \end{equation*} | ||
- | <panel type=" | + | The voltage at the open circuit |
- | + | \begin{equation*} U_{\rm S}= 2~V + 1~V + U_R \end{equation*} | |
- | {{youtube> | + | |
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- | <panel type=" | + | |
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- | {{youtube> | + | |
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- | </ | + | |
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- | <panel type=" | + | |
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- | {{youtube> | + | |
+ | </ | ||
+ | The values of the substitute resistor and the currents in the branches are | ||
+ | \begin{equation*} | ||
+ | \text{a)} \quad R=8~\Omega \qquad I=1.25~A \\ | ||
+ | \text{b)} \quad R=4~\Omega \qquad U=-5~V | ||
+ | \end{equation*} | ||
+ | </ | ||
</ | </ | ||
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===== Embedded resources ===== | ===== Embedded resources ===== | ||
- | < | + | < |
+ | DC Voltage & Current Source Theory | ||
{{youtube> | {{youtube> | ||
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<WRAP column half> | <WRAP column half> | ||
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{{youtube> | {{youtube> | ||
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<WRAP column half> | <WRAP column half> | ||
A more complex superposition example | A more complex superposition example | ||
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* A **linear (real) source** is fully determined by $(U_{\rm OC},I_{\rm SC})$ or equivalently $(U_0, | * A **linear (real) source** is fully determined by $(U_{\rm OC},I_{\rm SC})$ or equivalently $(U_0, | ||
* **Thevenin ↔ Norton**: $U_{\rm OC}=I_{\rm SC}R_{\rm i}$, $G_{\rm i}=1/R_{\rm i}$; deactivation rules let you find $R_{\rm i}$ quickly. | * **Thevenin ↔ Norton**: $U_{\rm OC}=I_{\rm SC}R_{\rm i}$, $G_{\rm i}=1/R_{\rm i}$; deactivation rules let you find $R_{\rm i}$ quickly. | ||
- | * **Efficiency vs. maximum power**: choose $R_{\rm L}\gg R_{\rm i}$ for high $\eta$, or $R_{\rm L}=R_{\rm i}$ for max $P_{\rm L}$. | ||
* **Two-terminal reductions** (e.g., loaded divider) simplify analysis of larger networks. | * **Two-terminal reductions** (e.g., loaded divider) simplify analysis of larger networks. | ||