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Electric Cicuites - Coggle Diagram
Electric Cicuites
Circuites
These are modesl of electricity using machines looked at from the point of view of electrical phenomena
Differen cicuites models:
"real cicuites
circuits that portays the essential function of hte device
Equivalent circuits
"Real" cicuits is made of a battery and almp. the construc of the circuit in the picture is the self-evident so it is a "real circuit
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Portraying the essential function. Small signal circuit of a trnsistor. the network in the picture portrays the essential function of the device which in this case is a transistor.
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Equivalent cicuits of a permenent magnet sunchronous machine. In this case there is no physical circuit but the functions of the machin can be reviewed with an equivalent circuit.
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Electri field and charge: The charges are repelling each other if their polarities are the same and attracting each other if their polarities are different.
The electric field is a power field that affects electric charges.
The unit of charge is coulomb (C) which is the charge that a current of one ampere transports in one second.
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Electric current: The electric field causes a power into the chrages. The charges beign to move creating a current which is according to the definition charges per second
The unit of current is ampere, which is defined as:
- The current of one ampere in two conductors that are one meter away from and parallel to each other and are infinitely long and slim in a vacuum, causes a force of 2 x 10^-7 Newton.
The positive direction of the current is the direction of the flow of the positive
charge which is opposite to the movement direction of electrons.
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Potential: This the amount of energy that is stored up, like how high an object wiht mass is. When in an electric field from potential V1 to V2, the potential of the charge changes.
Thus voltage is potential energy per unit of charge:
Voltage: One volt is the potential difference (voltage) between two points when one joule of energy is used to move one coulomb of charge from one point to the other.
While analyzing electric circuits, the potential difference, or more commonly known as voltage, is usually reviewed as well, the quantity being represented as u or U
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Passive circuit elements: An electrical device can have multiple of these properties. For general analyzing, it is also assumed that the passive elements are:
Lumped-circuit elements
linear
working in both directions
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Linearity: means that the amount of the feature is constant and it doesn't depend of for example the amount of current or voltage.
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Working in both directions: means that the feature of the circuit elemtn doesn't edepend of the direction of voltage or current, thus for example rectifiers aren't passive components
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Resistandc: resists the flow of current in wire, which is mesaured in ohms. One ohm (1 Ω) of resistance exists when there is one volt (1 V) of voltage losses with one ampere (1 A) of current flowing through the material
Based off Kirchhoff’s voltage law, the total voltage of a series
connection is the sum of the resistors’ voltage
By dividing the total current of a parallel connection with the voltage U, the
reciprocal of the resistance of the whole connection is
Conductanceg G: Dercribes the conduction of electricity. Is the recipocal of resistance, measure in Siemen(S). One Siemens (1 S) of conductance exists when there is one ampere (1 A) of
current in a material with one volt (1 V) applied across the material
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Volage and current formula of resistnace and conductance.
the waveforms of voltage and current as a function of time are in the same shape and in the case of the resistance, in the same phase.
Direct voltage equals direct current and in the same phase alternating current equals alternating current.
Capciatance C: Componenets properties eresists the changes in voltage. Stores enery into the electric field. Mesured in Faraday, nor maly wiht miltipliers like pico farday.
On direct current the capacitance has
a charge but the current is zero. The voltage of the capacitance grows (capacitance equals an open circuit)
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Sinusoidal voltage equals sinusoidal current but as a function of time, they are not in the same phase. The current of an ideal capacitor leads 90 ° the voltage.
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Inductance L: Compinents properties resists the changes of current. Stores energy into the magnetic field formed by the current. property of a conductor by which a change in current
in the conductor "induces" (creates) a voltage
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The current of an ideal coil equals the voltage but as a function of time, they are not in the same phase. The current lags 90 ° the voltage.
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Mutual inductance M: If the magnetic field of wire (that has a changing current and magnetic field) reaches another nearby wire, emf (electromotive force) is induced in the second conductor
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Active element in circuits: The soruce of electric energy are active parts in the circuites. These are voltage sources and current sources
Ideal Voltage Source: The voltage U of an ideal voltage source is a constant and is equally large as the potential differences forming in the device: U = E = source voltage or the electromotive force (emf)
A hibernating ideal voltage source doesn’t give a current or power when the circuit is open (picture a)
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Ideal current source: The current of an ideal current source is always constant: I = J = source current.
The ideal current source is in hibernation (its voltage is zero) when the
source is short circuited, picture a
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The ideal current source gets a voltage when a resistance R is added to the circuit, picture b
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Real energy Sources:
DC Voltage Source = Ideal voltage soruce + internal resistanceRs in a seris (picture a). Thus the voltage of the source is:
U=E-Rs*I
DC current source = ideal current source + internal conductance 𝐺𝑠 in a series (picture a). Thus the voltage of the source is:
𝐼 = 𝐽 − 𝐺𝑠*U
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AC Voltage Sources = ideal voltage source + internal Indcutance Lz in a seris(picture b). Thus the voltage of the source is:
u= e -Ls*(di/dt)
AC current source = ideal current source + internal capacitance 𝐶𝑠 in a series (picture b). Thus the voltage of the source is:
i = j-Cs(du/dt)
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