PLECS 3.7 Online Help

Capacitor

Purpose

Ideal capacitor

Library

Electrical / Passive Components

Description

pict pict

This component provides one or more ideal capacitors between its two electrical terminals. If the component is vectorized, a coupling can be modeled between the internal capacitors. Capacitors may be switched in parallel only if their momentary voltages are equal.

See section Configuring PLECS for information on how to change the graphical representation of capacitors.


Note  A capacitor may not be connected in parallel with an ideal voltage source. Doing so would create a dependency between an input variable (the source voltage) and a state variable (the capacitor voltage) in the underlying state-space equations.

Parameters

Capacitance
The value of the capacitor, in farads (F). All finite positive and negative values are accepted, including 0. The default is 100e-6.

In a vectorized component, all internal capacitors have the same value if the parameter is a scalar. To specify the capacitances individually use a vector [C1 C2...Cn]  . The length n   of the vector determines the component's width:

⌊    ⌋    ⌊                 ⌋  ⌊      ⌋
   i1        C1   0   ⋅⋅⋅  0       ddtv1
||  i2 ||    ||  0  C2   ⋅⋅⋅  0  ||  || ddtv2 ||
|⌈  .. |⌉  = |⌈  ..   ..   ..    .. |⌉ ⋅|⌈   ..  |⌉
   .         .   .    .   .      d-.
   in         0   0   ⋅⋅⋅  Cn      dtvn

In order to model a coupling between the internal capacitors enter a square matrix. The size n   of the matrix corresponds to the width of the component:

⌊  i ⌋    ⌊  C    C    ⋅⋅⋅ C    ⌋  ⌊ -dv  ⌋
|  1i |    | C 1    1C,2  ⋅⋅⋅ C 1,n |  | dtdv1 |
||  2. ||  = ||   2.,1   .2  .     2.,n || ⋅|| dt.2 ||
⌈  .. ⌉    ⌈   ..    ..    ..   ..  ⌉  ⌈   ..  ⌉
   in        Cn,1  Cn,2 ⋅⋅⋅  Cn       ddtvn

The capacitance matrix must be invertible, i.e. it may not be singular.

Initial voltage
The initial voltage of the capacitor at simulation start, in volts (V). This parameter may either be a scalar or a vector corresponding to the width of the component. The positive pole is marked with a "+". The initial voltage default is 0.

Probe Signals

Capacitor voltage
The voltage measured across the capacitor, in volts (V). A positive voltage is measured when the potential at the terminal marked with "+" is greater than the potential at the unmarked terminal.
Capacitor current
The current flowing through the capacitor, in amperes (A).