Main Content

Lead-Lag Filter

Implement first-order lead-lag filter

expand all in page
  • Lead-Lag Filter block

Libraries:
Simscape / Electrical / Specialized Power Systems / Control / Filters

Description

The Lead-Lag Filter block implements the following transfer function:

H(s)=1+T1s1+T2s

where

s=Laplace operatorT1,T2=time constants

This type of filter is used mainly for implementing lead-lag compensation in control systems. The key characteristics of the Lead-Lag Filter block are:

  • Input accepts a vectorized input of N signals, thus implementing N filters. This feature is particularly useful for designing controllers in three-phase systems (N=3).

  • The same block is used for continuous or discrete model. Changing the sample time Ts from 0 to a positive value automatically discretizes the filter, and vice versa.

  • Filter states can be initialized for specified DC inputs and outputs.

Examples

The power_LeadLagFilter example shows two uses of a vectorized Lead-Lag Filter.

The model sample time is parameterized with variable Ts (default value Ts = 50e-6). To simulate continuous filters, specify Ts = 0 in the MATLAB® Command Window before simulating the model.

Characteristics

Direct FeedthroughYes
Sample TimeSpecified in the Sample Time parameter
Continuous if Sample Time = 0
Scalar ExpansionYes, of the parameters
StatesOne state per filter
DimensionalizedYes

Ports

Input

expand all

Input signal the block applies the transfer function to.

Output

expand all

Output after the block has applied the transfer function.

Parameters

expand all

Specify the filter time constant(s) T1 in seconds.

Specify the filter time constant(s) T2 in seconds.

Specify the DC initial value of input and output signals. If the input signal is vectorized, specify a 1-by-N vector, where each value corresponds to a particular input.

Specify the sample time of the block, in seconds.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2013a