PLL
Determines the frequency and phase of the fundamental harmonic of the signal.
blockType: SubSystem
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Path in the library: |
Description
Block PLL Simulates a feedback control system based on phase-locked frequency (PLL), which monitors the frequency and phase of a sinusoidal signal using an internal frequency generator. The control system adjusts the frequency of the internal oscillator to maintain zero phase difference.
The figure shows the internal circuit of the PLL.
The input signal is mixed with the signal of the internal generator. The constant component of the mixed signal (proportional to the phase difference between these two signals) is allocated using the average value of the variable frequency. Proportional-integral-differential (PID) controller with additional automatic gain control (AGC) maintains the phase difference equal to 0 acting on a controlled generator. The output of the PID controller corresponding to the angular velocity is filtered and converted to a frequency in hertz, which is used to calculate the average value.
Ports
Output
#
Freq
—
measured frequency, Hz
scalar
Details
The measured frequency in Hz.
| Data types |
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| Complex numbers support |
No |
#
ωt
—
the angle synchronized with the zero intersection of the fundamental harmonic of the input signal is rad
scalar in the range [0, 2π]
Details
The angle in radians, varying from 0 before 2π, is synchronized with the zero crossings (leading edge) of the fundamental harmonic of the input signal.
| Data types |
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| Complex numbers support |
No |
Input
#
In
—
normalized input signal, O.E.
scalar
Details
Normalized input signal in relative units.
| Data types |
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| Complex numbers support |
No |
Parameters
Parameters
# Minimum frequency, Hz: — minimum expected input frequency
Details
The minimum expected frequency of the input signal. This parameter determines the size of the block buffer. Mean (Variable Frequency), used inside the block to calculate the average value.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# Initial inputs [Phase (deg), Frequency (Hz)]: — initial values of the phase and frequency of the input signal
Details
The initial values of the phase and frequency of the input signal.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# Regulator gains [Kp, Ki, Kd]: — proportional, integral and differential coefficients of the internal PID controller
Details
Proportional, integral and differential coefficients of the internal PID controller. Use these coefficients to adjust the PLL response time, outlier, and steady-state error.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# Time constant for derivative action, s: — the time constant for the first-order filter
Details
The time constant for the first-order filter.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# Maximum rate of change of frequency, Hz/s: — maximum positive and negative slope of the signal frequency
Details
The maximum positive and negative slope of the signal frequency.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# Filter cut-off frequency for frequency measurement, Hz: — the cutoff frequency of the second-order low-pass filter
Details
The cutoff frequency of the second-order low-pass filter.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# Sample time: — sampling period
Details
Specify the sampling period of the block in seconds. Set the value 0 to implement a continuous block.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# Enable automatic gain control — enabling automatic gain control
Details
When this check box is selected, the block PLL optimizes its operation by scaling the signal of the PID controller according to the magnitude of the input signal. Check this box if the input signal is not normalized.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |