# Variable Inductor

Linear time-varying inductor

**Library:**Simscape / Electrical / Passive

## Description

The Variable Inductor block represents a linear
time-varying inductor. The block provides two options for the relationship between the
voltage *v* across the device and the current through the inductor
*i* when the inductance at port L is *L*. The
**Equation** parameter determines which of the following equations
the block uses:

$$v=\frac{dL}{dt}i+L\frac{di}{dt}$$

Use the preceding equation when the inductance is defined as the ratio of the magnetic flux Ф to the steady-state current:

$$L(i)=\frac{\Phi (i)}{i}$$

$$v=L\frac{di}{dt}$$

Use the preceding equation when the inductance is defined as the local gradient of the flux-current curve for a given current:

$$L(i)=\frac{d\Phi (i)}{di}$$

The block includes a conductance in parallel with the variable inductor. You can use the conductor to represent the total insulation conductance of the inductor. You may need to use the conductor to prevent numerical issues for some circuit topologies, such as where a Variable Inductor block is connected in series with another inductor block that does not have a parallel conductance.

## Ports

### Input

### Conserving

## Parameters

## Extended Capabilities

## Version History

**Introduced in R2008a**