SOGI PLL

R2026b

Estimate phase angle and frequency of single-phase signal using second-order generalized integrator phase-locked loop

Since R2026b

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Libraries:
Power Converter Control with Motor Control Blockset / Signal Management

Description

The SOGI PLL block estimates the phase angle and frequency of a single-phase input signal using a second-order generalized integrator (SOGI) based phase-locked loop. Use this block to synchronize with grid voltage in single-phase power electronics applications such as inverters and active rectifiers. You can configure the position output format, PI controller gains, and frequency/position units.

Examples

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This example shows how to use the SOGI PLL block to track the phase angle of a single-phase grid voltage signal.

Add the SOGI PLL block to your model from the pcclib/Signal Management library.

Connect the grid voltage signal to the u input port and provide the initial frequency estimate to the ω0 port.

Use the θ output for the estimated phase angle and the ω output for the estimated frequency .

Ports

Input

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Single-phase input signal to track, specified as a scalar. Connect the voltage or current signal whose phase and frequency you want to estimate.

Data Types: single | double

Initial angular frequency estimate, specified as a scalar in rad/s. Provide the expected nominal frequency of the input signal to help the PLL lock faster.

Dependencies

To enable this port, set Initial frequency to Input port (default).

Data Types: single | double

PLL reset trigger signal, specified as a scalar. A rising edge on this port resets the internal integrators of the SOGI PLL.

Data Types: single | double | Boolean

Output

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Estimated phase angle of the input signal, returned as a scalar. The unit depends on the Position unit parameter setting.

Dependencies

To enable this port, set Position output to Angular position (default).

Data Types: single | double

Sine of the estimated phase angle, returned as a scalar.

Dependencies

To enable this port, set Position output to Sine and Cosine Position.

Data Types: single | double

Cosine of the estimated phase angle, returned as a scalar.

Dependencies

To enable this port, set Position output to Sine and Cosine Position.

Data Types: single | double

Estimated angular frequency of the input signal, returned as a scalar. The unit depends on the Frequency unit parameter setting.

Data Types: single | double

Parameters

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To edit block parameters interactively, use the Property Inspector. From the Simulink® Toolstrip, on the Simulation tab, in the Prepare gallery, select Property Inspector.

Select the format of the position output signals. When you select Angular position, the block outputs the phase angle on a single port. When you select Sine and Cosine Position, the block outputs the sine and cosine of the phase angle on separate ports.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: PosOut
Values: "Angular position" (default) | "Sine and Cosine Position"

Example: set_param(gcb,"PosOut","Sine and Cosine Position")

Sample time for the block discrete integration, specified as a positive scalar in seconds. This value determines how often the PLL updates its phase and frequency estimates. Set this to match your model's fixed-step solver step size. A smaller value improves tracking accuracy but increases computational load.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: BlkSampleTime
Values: "50e-6" (default) | positive scalar in quotes
Data Types: char | string

Example: set_param(gcb,"BlkSampleTime","100e-6")

Select the source of the initial frequency estimate. When you select Input port, the block accepts the initial frequency from the ω0 input port. When you select Specify via dialog, you specify the value using the Initial frequency value (Hz) parameter.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: InitialFreq
Values: "Input port" (default) | "Specify via dialog"

Example: set_param(gcb,"InitialFreq","Specify via dialog")

Initial frequency estimate for the PLL in Hz, specified as a positive scalar. This value seeds the SOGI filter for faster lock. Set this to the expected nominal grid frequency (50 or 60 Hz). A value closer to the actual signal frequency reduces the PLL settling time.

Dependencies

To enable this parameter, set Initial frequency to Specify via dialog.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: InitialFreqValue
Values: "50" (default) | positive scalar in quotes
Data Types: char | string

Example: set_param(gcb,"InitialFreqValue","60")

Damping ratio of the SOGI filter, specified as a positive scalar. This value controls the bandwidth and selectivity of the quadrature signal generator. A smaller value provides better harmonic rejection but slower transient response. A larger value improves dynamic tracking but reduces filtering of harmonics and noise.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: K
Values: "0.5" (default) | positive scalar in quotes
Data Types: char | string

Example: set_param(gcb,"K","0.707")

Proportional gain of the PI controller in the PLL loop, specified as a positive scalar. Increasing this value speeds up frequency tracking but can cause overshoot or oscillation. Decrease this value for smoother phase tracking with less noise sensitivity.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: Kp
Values: "100" (default) | positive scalar in quotes
Data Types: char | string

Example: set_param(gcb,"Kp","200")

Integral gain of the PI controller in the PLL loop, specified as a positive scalar. This gain eliminates steady-state frequency tracking error. Increasing this value reduces the time to eliminate frequency offset but may increase oscillation during transients.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: Ki
Values: "1000" (default) | positive scalar in quotes
Data Types: char | string

Example: set_param(gcb,"Ki","2000")

Number of data points in the sine/cosine lookup table, specified as a positive integer. Increasing this value improves the resolution of the angle-to-trigonometric conversion but uses more memory. Common values are 1024 or 2048 for a good balance between accuracy and memory usage on embedded targets.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: N_points
Values: "1024" (default) | positive integer in quotes
Data Types: char | string

Example: set_param(gcb,"N_points","2048")

Unit for the position output signal. Select Degrees for 0 to 360 range, Radians for 0 to 2*pi range, or Per-unit for 0 to 1 range.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: PositionUnit
Values: "Degrees" (default) | "Radians" | "Per-unit"

Example: set_param(gcb,"PositionUnit","Radians")

Data type for the position output signal. Specify single for embedded targets with limited floating-point support, or double when higher precision is needed for the phase angle output.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: PositionDataType
Values: "single" (default)
Data Types: char | string

Example: set_param(gcb,"PositionDataType","double")

Unit for the frequency output signal. Select Degrees/Sec for angular frequency in degrees per second, Radians/Sec for angular frequency in rad/s, or Hz for frequency in hertz.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: FrequencyUnit
Values: "Degrees/Sec" (default) | "Radians/Sec" | "Hz"

Example: set_param(gcb,"FrequencyUnit","Hz")

Data type for the frequency output signal. Specify single for embedded targets with limited floating-point support, or double when higher precision is needed for the frequency estimate.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: FrequencyDataType
Values: "single" (default)
Data Types: char | string

Example: set_param(gcb,"FrequencyDataType","double")

Data type for the internal sine/cosine lookup table. Specify single to reduce memory usage on embedded targets, or double to minimize quantization error in the trigonometric computations.

Programmatic Use

To set the block parameter value programmatically, use the set_param function.

Parameter: TableDataType
Values: "single" (default)
Data Types: char | string

Example: set_param(gcb,"TableDataType","double")

Extended Capabilities

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

HDL Code Generation
Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.

Fixed-Point Conversion
Design and simulate fixed-point systems using Fixed-Point Designer™.

Version History

Introduced in R2026b