1 Series/Parallel CircuitsSection
2 Concepts Studied So FarOhm’s Law: Victory Is Rare Power: P=IV KCL KVL
3 Outline Resistors in Series→ Req Resistors in Parallel → ReqVoltage Divider Circuits →Voltage divider formula Current Divider Circuits →Current divider formula
4 Resistors Connected in SeriesSeries-connected circuit elements carry the same current
5 Equivalent Resistor Req=R1+R2+R3….
6 Exercise Identify the resistors connected in series
7 Resistors in Parallel Parallel-connected circuit elements have the same voltage across their terminals
8 Equivalent Parallel Resistor1/Req=1/R1+1/R2+1/R3+1/R4
9 Series Parallel Simplification
10 P3.5 Find Rab
11 P3.7 Find Rab
12 The Voltage-Divider CircuitFunction: to develop more than one voltage level from a single voltage supply
13 A Voltage Divider Connected to a Load
14 The Current Divider Circuit
15 Example 3.3 Calculate power dissipated in the 6 Ohm resistor
16 Problem 3.14 vo(no load)=4 V vo(load)=3 V Find RL
17 3.15 Assume that only 0.5 W resistors are availableThe no-load voltage is to be the same as in the schematic. Specify the smallest values of R1 and R2
18 Application: Photovoltaic SystemSolar Cell I-V Characteristics Equation Series construction Parallel construction
19 I-V Characteristics of a Solar CellShort Circuit Current I(Isc) Open Circuit Voltage (Voc) I-V Characteristics shows all the possible operating point for the solar panel
20 Open Circuit Voltage MeasurementObservation: there is no current at Voc.
21 Short Circuit Current Measurement
22 Why is OK to short circuit a solar cell?It is possible to produce short circuit a solar panel because The current comes from the electrons produced by the solar cell. Only some of the photons striking the solar cell are converted into current. The current produced by the solar cell is finite.
23 Power Produced by Solar CellP=IV Observation: No power is produced at Voc and Isc. Why?
24 Example If Vmp is 15 V and Imp is 3A, what resistance is requiredin order to operate the solar cell at its maximum power? Answer: A 5 Ohm load.
25 Rule of Thumb Solar cells are generally connected in series to achieve a desired voltage. The serial connected solar cells are connected in parallel to build current and power. Cells are connected to form modules and modules are connected to form array.
26 Connect Cells/Modules in SeriesIndividual cells are connected in series by soldering the metal strip from top surface (- terminal) of one cell to the back surface (+ terminal) of the next
27 Use Series Connection to Increase VoltageYou want to use cells of matching current capacity!
28 Use Parallel Construction to Increase Current(Acquire proper voltage)
29 Increase Current Capacity by Connecting Cells in Paralell