ECEN 215, Principles of Electrical EngineeringDr. Mina RahimianLecture# 13 Date: 10/7/13Chapter 5, Sinusoidal Steady State ResponseIn this chapter we will analyze circuits that are energized by time varying voltage or current sources. In particular we are interested in sinusoidal sources. A sinusoidal signal is easy to generate and transmit. The form of voltage generated at power plants and supplied to homes and factories is the sinusoidal voltage. A sinusoidal source is usually referred to as alternating current or ac source.rms value:The rms value of an ac voltage is its equivalent dc value that delivers the same amount of power to two identical loads.PhasorsThe response of an ac circuit is the sum of the transient response and the steady state. The transient response is dictated by the nature of the circuit. The steady state has the same form as the excitation. If a circuit is excited by a sinusoidal source, the steady state response is also sinusoidal at the same frequency as the source but different amplitude and phase angle.Because of this characteristic, we don't have to carry the frequency in our calculation. Phasor is a complex number that carries the amplitude and phase angle of a sinusoidal function.Complex calculations (review)Resistor in phasor domainPhasor transform of circuit elementsIf we find the V-I relationship of the circuit elements, in phasor domain, we can find the phasor transform of the element.Inductor in phasor domainIn phasor domain all circuit elements behave as resistors, having a linear relationship between their voltages and currents.The ratio of V/I is called impedance.Capacitor in phasor
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