Implement second-order variable-tuned filter
Depending on the Filter type selected in the block menu, the Second-Order Filter block implements the following transfer function. The Fn input determines the filter natural frequency of the filter.
Bandstop (Notch) filter:
Specify the type of filter: Lowpass, Highpass, Bandpass, or Bandstop (notch).
The initial natural frequency of the filter, in hertz. This value must be a scalar or a vector.
Specify the damping ratio of the filter. The damping ratio is typically a value between 0 and 1.
The damping ratio is related to the filter quality factor Q:
For a bandpass or a bandstop filter, the 3 dB bandwidth is given by
Specify the sample time of the block, in seconds. Set to 0 to implement a continuous block.
When this check box is selected, filter states are initialized according to the AC initial input and DC initial input parameters.
Specify the magnitude of the initial AC component of the input signal, its phase, in degrees, and its frequency, in hertz.
When the input is vectorized (N signals), specify an N-by-3 matrix, where each row of the matrix corresponds to a particular input.
The AC initial input parameter is visible only when the Initialize filter states parameter is selected.
Specify the value of the initial DC component of the input signal. When the input signal is vectorized, specify a 1-by-N vector, where each value corresponds to a particular input.
The DC initial input parameter is visible only when the Initialize filter states parameter is selected.
The inputs accept vectorized signals of N values, thus implementing N filters. This capability is particularly useful for designing controllers in three-phase systems (N = 3).
|Sample Time||Specified in the Sample Time parameter|
Continuous if Sample Time = 0
|Scalar Expansion||Yes, of the parameters|
|States||Two states per filter|
The power_SecondOrderFilterTunedpower_SecondOrderFilterTuned example shows various uses of the Second-Order Filter (Variable-Tuned) block with two Filter type parameter settings (Lowpass and Bandstop).
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 starting the simulation.