Unterschiede
Hier werden die Unterschiede zwischen zwei Versionen angezeigt.
| Nächste Überarbeitung | Vorhergehende Überarbeitung | ||
| electrical_engineering_and_electronics_1:block07 [2025/09/29 01:13] – angelegt mexleadmin | electrical_engineering_and_electronics_1:block07 [2026/01/10 13:18] (aktuell) – mexleadmin | ||
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| Zeile 1: | Zeile 1: | ||
| - | ====== Block 07 — Power-relevant | + | ====== Block 07 — Power-relevant |
| - | ===== Learning objectives | + | ===== 7.0 Intro ===== |
| + | |||
| + | ==== 7.0.1 Learning Objectives | ||
| < | < | ||
| * Define and compute **input/ | * Define and compute **input/ | ||
| Zeile 13: | Zeile 15: | ||
| ~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
| + | ==== 7.0.2 Preparation at Home ==== | ||
| - | ===== 90-minute plan ===== | + | And again: |
| + | * Please read through the following chapter. | ||
| + | * Also here, there are some clips for more clarification under ' | ||
| + | |||
| + | For checking your understanding please do the following exercises: | ||
| + | * 7.1 | ||
| + | * E3.3.3 | ||
| + | |||
| + | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
| + | ==== 7.0.3 90-minute plan ==== | ||
| - Warm-up (8 min): recall passive/ | - Warm-up (8 min): recall passive/ | ||
| - Core concepts (35 min): real source model; definitions of $\eta$ and $\varepsilon$; | - Core concepts (35 min): real source model; definitions of $\eta$ and $\varepsilon$; | ||
| Zeile 22: | Zeile 34: | ||
| - Wrap-up (5 min): summary + pitfalls. | - Wrap-up (5 min): summary + pitfalls. | ||
| - | ===== Conceptual | + | ==== 7.0.4 Conceptual |
| <callout icon=" | <callout icon=" | ||
| - | - Real sources are modeled by an **ideal source** plus **internal resistance** $R_{\rm i}$; the terminal voltage **drops under load**. | + | - Real sources are modeled by an **ideal source** plus **internal resistance** $R_{\rm i}$; the terminal voltage **drops under load**. |
| - | - **Efficiency** $\eta$ compares *delivered* to *drawn* power. In the simple DC source–load case, $\displaystyle \eta=\frac{R_{\rm L}}{R_{\rm L}+R_{\rm i}}$ (dimensionless). High-efficiency design wants $R_{\rm L}\gg R_{\rm i}$. : | + | - **Efficiency** $\eta$ compares |
| - | - **Utilization rate** $\varepsilon$ compares delivered power to the **maximum** available from the ideal source: $\displaystyle \varepsilon=\frac{R_{\rm L}R_{\rm i}}{(R_{\rm L}+R_{\rm i})^2}$. It peaks at $R_{\rm L}=R_{\rm i}$ with $\varepsilon_{\max}=25~\%$. This is the **maximum power transfer** condition. | + | - **Utilization rate** $\varepsilon$ compares delivered power to the **maximum** available from the ideal source: $\displaystyle \varepsilon=\frac{R_{\rm L}R_{\rm i}}{(R_{\rm L}+R_{\rm i})^2}$. It peaks at $R_{\rm L}=R_{\rm i}$ with $\varepsilon_{\max}=25~\%$. This is the **maximum power transfer** condition. |
| - Different goals → different $R_{\rm L}$: | - Different goals → different $R_{\rm L}$: | ||
| - | * **Power engineering**: | + | * **Power engineering**: |
| - | * **Communications** (matching, antennas, RF): maximize $P_{\rm L}$ → $R_{\rm L}=R_{\rm i}$, $\eta=50~\%$. | + | * **Communications** (matching, antennas, RF): maximize $P_{\rm L}$ → $R_{\rm L}=R_{\rm i}$, $\eta=50~\%$. |
| </ | </ | ||
| - | <callout icon=" | ||
| - | We use **conventional current** and the **passive/ | ||
| - | </ | ||
| ~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
| + | ===== 7.1 Core Content ===== | ||
| - | ===== Core content ===== | + | ==== 7.1.1 Power Measurement ==== |
| - | + | ||
| - | ==== Power Measurement ==== | + | |
| First, it is necessary to consider how to determine the power. The power meter (or wattmeter) consists of a combined ammeter and voltmeter. | First, it is necessary to consider how to determine the power. The power meter (or wattmeter) consists of a combined ammeter and voltmeter. | ||
| Zeile 51: | Zeile 59: | ||
| ~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
| - | ==== Power and Characteristics in Diagrams ==== | + | ==== 7.1.2 Power and Characteristics in Diagrams ==== |
| The simulation in <imgref imageNo13 > shows the following: | The simulation in <imgref imageNo13 > shows the following: | ||
| Zeile 87: | Zeile 95: | ||
| The whole context can be investigated in this [[https:// | The whole context can be investigated in this [[https:// | ||
| - | ==== The Characteristics: | + | ==== 7.1.3 The Efficiency ==== |
| To understand the lower diagram in <imgref imageNo14 >, the definition equations of the two reference quantities shall be described here again: | To understand the lower diagram in <imgref imageNo14 >, the definition equations of the two reference quantities shall be described here again: | ||
| Zeile 102: | Zeile 110: | ||
| Application: | Application: | ||
| - In __power engineering__ $\eta \rightarrow 100\%$ is often desired: We want the maximum power output with the lowest losses at the internal resistance of the source. Thus, the internal resistance of the source should be low compared to the load $R_{\rm L} \gg R_{\rm i} $. | - In __power engineering__ $\eta \rightarrow 100\%$ is often desired: We want the maximum power output with the lowest losses at the internal resistance of the source. Thus, the internal resistance of the source should be low compared to the load $R_{\rm L} \gg R_{\rm i} $. | ||
| + | |||
| + | ==== 7.1.4 The Utilization Rate ==== | ||
| The **utilization rate** | The **utilization rate** | ||
| Zeile 117: | Zeile 127: | ||
| Application: | Application: | ||
| - | - In __communications engineering__ the impedance matching of the source (the antenna) and the load (the signal-acquiring microcontroller) uses resistors, capacitors, and inductors. | + | - In __communications engineering__ the impedance matching of the source (the antenna) and the load (the signal-acquiring microcontroller) uses resistors, capacitors, and inductors. |
| - Furthermore, | - Furthermore, | ||
| Zeile 123: | Zeile 133: | ||
| ~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
| - | ==== Power-flow chains (series stages) ==== | + | |
| + | <panel type=" | ||
| + | **Given:** $U_0=12.0~\rm V$, $R_{\rm i}=0.50~\Omega$, | ||
| + | **Find:** $U_{\rm L}$, $I_{\rm L}$, $P_{\rm L}$, $\eta$, $\varepsilon$. | ||
| + | |||
| + | \begin{align*} | ||
| + | I_{\rm L} &= \frac{12.0~{\rm V}}{0.50~\Omega+5.0~\Omega} = 2.182~{\rm A} \\ | ||
| + | U_{\rm L} &= I_{\rm L} R_{\rm L}= 2.182~{\rm A}\cdot 5.0~\Omega = 10.91~{\rm V} \\ | ||
| + | P_{\rm L} &= U_{\rm L}I_{\rm L} = 10.91~{\rm V}\cdot 2.182~{\rm A}= 23.8~{\rm W} \\ | ||
| + | P_{\rm in, | ||
| + | \eta &= \frac{R_{\rm L}}{R_{\rm i}+R_{\rm L}}=\frac{5.0~\Omega}{5.50~\Omega}=0.909=90.9~\% \\ | ||
| + | \varepsilon &= \frac{R_{\rm L}R_{\rm i}}{(R_{\rm L}+R_{\rm i})^2}=\frac{5.0\cdot 0.50}{(5.50)^2}=0.0826=8.26~\% | ||
| + | \end{align*} | ||
| + | |||
| + | Interpretation: | ||
| + | </ | ||
| + | |||
| + | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
| + | ==== 7.1.5 Power-flow chains (series stages) ==== | ||
| The usable (= outgoing) $P_{\rm O}$ power of a real system is always smaller than the supplied (incoming) power $P_{\rm I}$. | The usable (= outgoing) $P_{\rm O}$ power of a real system is always smaller than the supplied (incoming) power $P_{\rm I}$. | ||
| Zeile 147: | Zeile 175: | ||
| ~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
| - | ==== Utilization rate $\varepsilon$ | + | ===== 7.2 Common pitfalls ===== |
| - | Define the **best-case input power** of the ideal source as $P_{\rm in,max}=\dfrac{U_0^2}{R_{\rm i}}$. Then | + | - Forgetting |
| - | \begin{align*} | + | - Mixing up **goals**: high $\eta$ vs. high $P_{\rm L}$ lead to **different** $R_{\rm L}$. |
| - | \boxed{\; | + | - Using **ideal source** formulas for a **real** source |
| - | \end{align*} | + | - Ignoring the **sign convention** when interpreting |
| - | Maximization gives $R_{\rm L}=R_{\rm i}$ and $\varepsilon_{\max}=25~\%$. | + | |
| - | ~~PAGEBREAK~~ ~~CLEARFIX~~ | + | ===== 7.3 Exercises ===== |
| - | + | ||
| - | <panel type=" | + | |
| - | **Given:** $U_0=12.0~\rm V$, $R_{\rm i}=0.50~\Omega$, | + | |
| - | **Find:** $U_{\rm L}$, $I_{\rm L}$, $P_{\rm L}$, $\eta$, $\varepsilon$. | + | |
| - | + | ||
| - | \begin{align*} | + | |
| - | I_{\rm L} &= \frac{12.0~{\rm V}}{0.50~\Omega+5.0~\Omega} = 2.182~{\rm A} \\ | + | |
| - | U_{\rm L} &= I_{\rm L} R_{\rm L}= 2.182~{\rm A}\cdot 5.0~\Omega = 10.91~{\rm V} \\ | + | |
| - | P_{\rm L} &= U_{\rm L}I_{\rm L} = 10.91~{\rm V}\cdot 2.182~{\rm A}= 23.8~{\rm W} \\ | + | |
| - | P_{\rm in, | + | |
| - | \eta &= \frac{R_{\rm L}}{R_{\rm i}+R_{\rm L}}=\frac{5.0~\Omega}{5.50~\Omega}=0.909=90.9~\% \\ | + | |
| - | \varepsilon &= \frac{R_{\rm L}R_{\rm i}}{(R_{\rm L}+R_{\rm i})^2}=\frac{5.0\cdot 0.50}{(5.50)^2}=0.0826=8.26~\% | + | |
| - | \end{align*} | + | |
| - | + | ||
| - | Interpretation: | + | |
| - | </ | + | |
| - | + | ||
| - | ~~PAGEBREAK~~ ~~CLEARFIX~~ | + | |
| - | + | ||
| - | ===== Exercises ===== | + | |
| <panel type=" | <panel type=" | ||
| A source has $U_0=9.0~\rm V$, $R_{\rm i}=1.0~\Omega$. | A source has $U_0=9.0~\rm V$, $R_{\rm i}=1.0~\Omega$. | ||
| - (a) Choose $R_{\rm L}=9.0~\Omega$. Compute $I_{\rm L}$, $U_{\rm L}$, $P_{\rm L}$, $\eta$, $\varepsilon$. | - (a) Choose $R_{\rm L}=9.0~\Omega$. Compute $I_{\rm L}$, $U_{\rm L}$, $P_{\rm L}$, $\eta$, $\varepsilon$. | ||
| - | - (b) Choose $R_{\rm L}=1.0~\Omega$. Repeat. Which choice maximizes $P_{\rm L}$? Which yields higher $\eta$? | + | - (b) Choose $R_{\rm L}=1.0~\Omega$. Repeat. |
| - | **Strategy: | + | **Strategy: |
| </ | </ | ||
| Zeile 189: | Zeile 196: | ||
| </ | </ | ||
| - | <panel type=" | + | <wrap anchor # |
| - | Simplify the following circuits (//NT// for Norton, //TT// for Thevenin) to a single source plus $R_{\rm i}$, then compute $U_{\rm L}$ and $\eta$ for a given $R_{\rm L}$. | + | <panel type=" |
| - | < | + | |
| - | </ | + | |
| - | Tip: Short ideal voltage sources and open ideal current sources to determine the internal resistance. : | + | |
| - | </ | + | |
| - | <panel type=" | + | For the company „HHN Mechatronics & Robotics“ you shall analyze a competitor product: a simple drilling machine. This contains a battery pack, some electronics, |
| - | Design | + | |
| - | < | + | |
| - | < | + | |
| - | </ | + | |
| - | {{drawio> | + | |
| - | </ | + | |
| - | (Use the prompts inside the panel text on the source page for guidance.) : | + | |
| - | </ | + | |
| - | ~~PAGEBREAK~~ ~~CLEARFIX~~ | + | The drill has two speed-modes: |
| + | - max power: here, the motor is directly connected to the battery. | ||
| + | - reduced power: in this case, a shunt resistor $R_{\rm s} = 1 ~\Omega$ is connected in series to the motor. | ||
| - | ===== Applications & remarks ===== | + | {{drawio> |
| - | * **Communications / RF**: power matching networks (R, L, C) to get maximum signal power; see {{https://www.youtube.com/ | + | |
| - | * **Photovoltaics**: | + | |
| + | |||
| + | Tasks: | ||
| + | - Calculate the input and output power for both modes. | ||
| + | - What are the efficiencies for both modes? | ||
| + | - Which value should the shunt resistor $R_s$ have, when the reduced power should be exactly half of the maximum power? | ||
| + | - Your company uses the reduced power mode instead of the shunt resistor $R_{\rm s}$ multiple diodes in series $D$, which generates a constant voltage drop of $U_D = 2.8 ~V$. \\ What are the input and output power, such as the efficiency in this case? | ||
| + | |||
| + | You can check your results for the currents, voltages, and powers with the following simulation: | ||
| + | |||
| + | {{url> | ||
| + | |||
| + | </ | ||
| + | |||
| + | # | ||
| + | |||
| + | Two heater resistors (both with $R_\rm L = 0.5 ~\Omega$) shall be supplied with two lithium-ion-batteries (both with $U_{\rm S} = 3.3 ~\rm V$, $R_{\rm i} = 0.1 ~\Omega$). | ||
| + | |||
| + | 1. What are the possible ways to connect these components? | ||
| + | |||
| + | # | ||
| + | {{drawio> | ||
| + | # | ||
| + | |||
| + | 2. Which circuit can provide the maximum power $P_{\rm L ~max}$ at the loads? | ||
| + | |||
| + | # | ||
| + | |||
| + | At the maximum utilization rate $\varepsilon = 0.25$ the maximum power $P_{\rm L ~max}$ can be achieved. \\ | ||
| + | The utilization rate is given as: | ||
| + | \begin{align*} | ||
| + | \varepsilon &= {{P_{\rm out}}\over{P_{\rm in, max}}} | ||
| + | &= {{R_{\rm L}\cdot R_{\rm i}} \over {(R_{\rm L}+R_{\rm i})^2}} \\ | ||
| + | \end{align*} | ||
| + | |||
| + | As near the resulting equivalent internal resistance approaches the resulting equivalent load resistance, as higher the utilization rate $\varepsilon$ will be.\\ | ||
| + | Therefore, a series configuration of the batteries ($2 R_{\rm i} = 0.2~\Omega$) and a parallel configuration of the load (${{1}\over{2}} R_{\rm L}= 0.25~\Omega$) will have the highest output. | ||
| + | # | ||
| + | |||
| + | # | ||
| + | The following configuration has the maximum output power. | ||
| + | |||
| + | {{drawio> | ||
| + | # | ||
| + | |||
| + | |||
| + | 3. What is the value of the maximum power $P_{\rm L ~max}$? | ||
| + | |||
| + | # | ||
| + | The maximum utilization rate is: | ||
| + | \begin{align*} | ||
| + | \varepsilon &= {{{{1}\over{2}} R_{\rm L} \cdot 2 R_{\rm i} } \over { ({{1}\over{2}} R_{\rm L} + 2 R_{\rm i} )^2}} \\ | ||
| + | &= { {0.25 ~\Omega | ||
| + | &= 24.6~\% | ||
| + | \end{align*} | ||
| + | |||
| + | Therefore, the maximum power is: | ||
| + | \begin{align*} | ||
| + | \varepsilon | ||
| + | \rightarrow P_{\rm out} &= \varepsilon | ||
| + | & | ||
| + | & | ||
| + | \end{align*} | ||
| + | |||
| + | # | ||
| + | |||
| + | # | ||
| + | \begin{align*} | ||
| + | P_{\rm out} = 26.8 W | ||
| + | \end{align*} | ||
| + | # | ||
| + | |||
| + | 4. Which circuit has the highest efficiency? | ||
| + | |||
| + | # | ||
| + | The highest efficiency $\eta$ is given when the output power compared to the input power is minimal. \\ | ||
| + | A parallel configuration of the batteries (${{1}\over{2}} R_{\rm i} = 0.05~\Omega$) and a series configuration of the load ($2 R_{\rm L}= 1.0~\Omega$) will have the highest efficiency. | ||
| + | # | ||
| + | |||
| + | # | ||
| + | {{drawio> | ||
| + | # | ||
| + | |||
| + | 5. What is the value of the highest efficiency? | ||
| + | |||
| + | # | ||
| + | The efficiency $\eta$ is given as: | ||
| + | \begin{align*} | ||
| + | \eta &= { {2 R_{\rm L} }\over{ 2 R_{\rm L}+ {{1}\over{2}} R_{\rm i} }} \\ | ||
| + | &= { { 1.0~\Omega }\over{ 1.0~\Omega + 0.05~\Omega }} | ||
| + | \end{align*} | ||
| + | |||
| + | # | ||
| + | |||
| + | # | ||
| + | \begin{align*} | ||
| + | \eta = 95.2~\% | ||
| + | \end{align*} | ||
| + | # | ||
| + | \\ \\ | ||
| + | # | ||
| + | {{drawio> | ||
| + | |||
| + | # | ||
| + | |||
| + | |||
| + | # | ||
| + | |||
| + | {{page> | ||
| + | |||
| + | |||
| + | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||
| ===== Summary ===== | ===== Summary ===== | ||
| < | < | ||
| - Real sources: $U_{\rm L}=U_0 \dfrac{R_{\rm L}}{R_{\rm i}+R_{\rm L}}$, $I_{\rm L}=\dfrac{U_0}{R_{\rm i}+R_{\rm L}}$; $P_{\rm L}=\dfrac{U_0^2 R_{\rm L}}{(R_{\rm i}+R_{\rm L})^2}$. | - Real sources: $U_{\rm L}=U_0 \dfrac{R_{\rm L}}{R_{\rm i}+R_{\rm L}}$, $I_{\rm L}=\dfrac{U_0}{R_{\rm i}+R_{\rm L}}$; $P_{\rm L}=\dfrac{U_0^2 R_{\rm L}}{(R_{\rm i}+R_{\rm L})^2}$. | ||
| - | - **Efficiency**: | + | - **Efficiency**: |
| - | - **Utilization rate**: $\displaystyle \varepsilon=\dfrac{R_{\rm L}R_{\rm i}}{(R_{\rm L}+R_{\rm i})^2}$; peak $\varepsilon_{\max}=25~\%$ at $R_{\rm L}=R_{\rm i}$ (maximum power transfer; $\eta=50~\%$). | + | - **Utilization rate**: $\displaystyle \varepsilon=\dfrac{R_{\rm L}R_{\rm i}}{(R_{\rm L}+R_{\rm i})^2}$; peak $\varepsilon_{\max}=25~\%$ at $R_{\rm L}=R_{\rm i}$ (maximum power transfer; $\eta=50~\%$). |
| - | - **Chain efficiencies** multiply: $\eta_{\rm total}=\prod \eta_i$. | + | - **Chain efficiencies** multiply: $\eta_{\rm total}=\prod \eta_i$. |
| - | - Thevenin/ | + | - Thevenin/ |
| - **Max efficiency $\eta$**: $R_{\rm L}\rightarrow\infty$ (relative to $R_{\rm i}$) → small current, small loss. | - **Max efficiency $\eta$**: $R_{\rm L}\rightarrow\infty$ (relative to $R_{\rm i}$) → small current, small loss. | ||
| - **Max delivered power $P_{\rm L}$**: $R_{\rm L}=R_{\rm i}$ (impedance matching). See also {{https:// | - **Max delivered power $P_{\rm L}$**: $R_{\rm L}=R_{\rm i}$ (impedance matching). See also {{https:// | ||
| </ | </ | ||
| - | </ | ||
| - | ===== Common pitfalls checklist ===== | ||
| - | - Forgetting **units** in intermediate results (always write $x = \text{number} \times \text{unit}$). | ||
| - | - Mixing up **goals**: high $\eta$ vs. high $P_{\rm L}$ lead to **different** $R_{\rm L}$. | ||
| - | - Using **ideal source** formulas for a **real** source (always include $R_{\rm i}$). | ||
| - | - Ignoring the **sign convention** when interpreting $P=U\cdot I$ (source vs. load). | ||
| ~~PAGEBREAK~~ ~~CLEARFIX~~ | ~~PAGEBREAK~~ ~~CLEARFIX~~ | ||