Phasor Addition Help

Discussion in 'General Electronics Chat' started by ctishman, Jan 25, 2013.

  1. ctishman

    Thread Starter New Member

    Oct 12, 2011
    9
    0
    So I'm trying to work my way through some of the exercises in my ac course, but I just can't seem to make it make sense. Anyhow, I was hoping someone would be able to help me out with it.

    The example I'm given, and I'm quoting from this (terrible) textbook:

    Anyhow, the entire book reads like it was written from one engineer to another engineer, rather than to a student, but I won't get into that too much. I'm just trying to figure out what the heck they're doing and how it's supposed to work to add phasors together.

    *note that section 14.10 says nothing about adding vectors in polar form, and everything I've seen seems to indicate that it's impossible unless the angles are multiples of 180°.
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,442
    3,361
    Firstly, know how to convert from polar coordinates to orthogonal coordinates (same as Cartesian or X-Y coordinates) and vice versa.

    For example,

    1V[​IMG]0° + 2V[​IMG]90° = 2.236V[​IMG]63.43°

    work backwards:

    2.236V[​IMG]63.43°

    is

    x = r cos(θ), i.e. x = 1

    y = r sin(θ), i.e. y = 2

    Thus, to add two vectors, convert to X-Y coordinates and add the X-values and the Y-values. Then convert to polar coordinates:

    r = √(x^2 + y^2)

    θ = atan(y/x)
     
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  3. ctishman

    Thread Starter New Member

    Oct 12, 2011
    9
    0
    Okay, NOW it makes sense! I'd been banging my head about it for hours and had lost perspective. I really appreciate the help with that!
     
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