PR Controller

R2026b

Implement a proportional-resonant controller for AC signal tracking

Since R2026b

• 

PR Controller block

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Libraries:
Power Converter Control with Motor Control Blockset / Control / Renewables

Description

The PR Controller block implements a discrete proportional-resonant (PR) controller for tracking AC reference signals at a specific resonant frequency. Use this block in grid-connected renewable energy applications where you need to achieve zero steady-state error for sinusoidal signals. You can configure the controller in ideal or damped mode, specify gains and resonant frequency through dialog parameters or input ports, and apply output saturation with optional anti-windup.

• Ideal Form

  

• Damped Form

  

Ports

Input

u — Controller error input signal

scalar

Error signal (reference minus feedback) for the PR controller, specified as a scalar. The block applies proportional and resonant action to this signal to produce the control output. Compute this value externally by subtracting the measured AC quantity from its reference before connecting to this port.

Data Types: double | single

K_p — Proportional gain input

scalar

Proportional gain for the PR controller, specified as a positive scalar. The block uses this value to scale the wideband proportional response. Increasing proportional gain improves transient response speed but may reduce stability margins.

Dependencies

To enable this port, set Source (gains) to Input port.

Data Types: double | single

K_r — Resonant gain input

scalar

Resonant gain for the PR controller, specified as a positive scalar. The block uses this value to set the magnitude of the resonant peak at the configured resonant frequency. Increasing the resonant gain reduces steady-state AC tracking error but very large values can cause oscillation near the resonant frequency.

Dependencies

To enable this port, set Source (gains) to Input port.

Data Types: double | single

f₀ — Resonant frequency input

scalar

Resonant frequency of the PR controller in hertz, specified as a positive scalar. The block uses this value to tune its internal resonant element. Set this to the fundamental grid frequency (50 Hz or 60 Hz) to track sinusoidal AC currents or voltages at that frequency.

Dependencies

To enable this port, set Resonant frequency source to Input port.

Data Types: double | single

T_s — Discrete step size input

scalar

Discrete sample time of the controller in seconds, specified as a positive scalar. The block uses this value to parameterize the discrete resonant element at run time. This port allows runtime configuration of the sample time without recompiling the model.

Dependencies

To enable this port, select the Use Discrete step size as input port parameter.

Data Types: double | single

Rst — Controller state reset trigger

scalar

Boolean signal that resets the controller integrator states when asserted (nonzero), specified as a scalar. When asserted, the block resets both the forward-path integrator and the feedback integrator to zero. Use this port to initialize the controller at startup or after a fault condition to avoid transient spikes.

Data Types: double | single

Output

y — PR controller output signal

scalar

PR controller output combining the proportional and resonant components, output as a scalar. The block sums both components and applies output saturation if enabled. Connect this signal to the modulator or the input of a PWM generation block.

Data Types: double | single

Parameters

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

Controller Tab

Control type — Type of proportional-resonant controller

Ideal (default) | Damped

Select Ideal for an ideal PR controller with theoretically infinite gain at the resonant frequency. This mode achieves zero steady-state error for sinusoidal signals at the resonant frequency but is more sensitive to frequency deviations.

Select Damped for a non-ideal PR controller with a finite gain peak whose width is determined by the Cutoff frequency (Hz), fс parameter. Use this mode when the grid frequency fluctuates and you need a broader tracking bandwidth around the resonant frequency.

Programmatic Use

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

To get the block parameter value programmatically, use the get_param function.

Parameter:	Controller
Values:	"Ideal" (default) | "Damped"

Example: set_param(gcb,"Controller","Damped")

Use Discrete step size as input port — Option to specify discrete step size through an input port

off (default) | on

Option to specify the discrete step size through an input port instead of a dialog parameter. Select this parameter to enable the T_s input port, which allows the sample time to vary at run time. When cleared, the block uses the fixed value from the Discrete step size (s) parameter.

Programmatic Use

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

To get the block parameter value programmatically, use the get_param function.

Parameter:	BlkSampleTimeInport
Values:	"off" (default) | "on"

Example: set_param(gcb,"BlkSampleTimeInport","on")

Discrete step size (s) — Discrete step size for the controller

50e-6 (default) | positive scalar

Discrete step size for the controller, specified in seconds, as a positive scalar. The block uses this value to parameterize the resonant element and determine the execution rate. This value must be small enough relative to the resonant frequency to avoid discretization errors. Set this to match the PWM switching period or inverter control sample time.

Dependencies

This parameter is visible when Use Discrete step size as input port is cleared.

Programmatic Use

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

To get the block parameter value programmatically, use the get_param function.

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

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

Source — Source of proportional and resonant gains

Specify via dialog (default) | Input port

Select Specify via dialog to enter the proportional and resonant gain values in the block parameters dialog box. The Proportional (Kp) and Resonant (Kr) parameters become visible.

Select Input port to provide gains at run time through the K_p and K_r input ports. Use this mode for adaptive gain scheduling or hardware-in-the-loop tests where gains change during simulation.

Programmatic Use

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

To get the block parameter value programmatically, use the get_param function.

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

Example: set_param(gcb,"MainSource","Input port")

Proportional (Kp) — Proportional gain of the controller

1 (default) | positive scalar

Proportional gain of the PR controller, specified as a positive scalar. The block uses this value to scale the wideband proportional response. This gain determines the wideband response and affects disturbance rejection at all frequencies. Increasing it improves transient response but can reduce stability margin.

Dependencies

This parameter is visible when Source is set to Specify via dialog.

Programmatic Use

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

To get the block parameter value programmatically, use the get_param function.

Parameter:	Proportional
Values:	"1" (default) | positive scalar in quotes
Data Types:	char | string

Example: set_param(gcb,"Proportional","2")

Resonant (Kr) — Resonant gain of the controller

1 (default) | positive scalar

Resonant gain of the PR controller, specified as a positive scalar. The block uses this value to set the magnitude of the resonant peak at the configured resonant frequency. Increasing it reduces steady-state tracking error for sinusoidal signals but a very large value can cause oscillation near the resonant frequency.

Dependencies

This parameter is visible when Source is set to Specify via dialog.

Programmatic Use

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

To get the block parameter value programmatically, use the get_param function.

Parameter:	Integral
Values:	"1" (default) | positive scalar in quotes
Data Types:	char | string

Example: set_param(gcb,"Integral","5")

Resonant frequency source — Source of the resonant frequency value

Specify via dialog (default) | Input port

Select Specify via dialog to enter the resonant frequency in the block parameters dialog box. The Resonant frequency (Hz), f₀ parameter becomes visible.

Select Input port to provide the frequency at run time through the f₀ input port. Use this mode when the grid frequency varies and you need the controller to track frequency in real time.

Programmatic Use

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

To get the block parameter value programmatically, use the get_param function.

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

Example: set_param(gcb,"InputFrequencyType","Input port")

Resonant frequency (Hz), f₀ — Resonant frequency of the controller

50 (default) | positive scalar

Resonant frequency of the controller, specified in hertz as a positive scalar. The block uses this value to tune the resonant element so it provides high gain at this frequency for zero steady-state error tracking. Set this to the fundamental grid frequency (50 or 60 Hz) or a harmonic frequency you want to track or reject.

Dependencies

This parameter is visible when Resonant frequency source is set to Specify via dialog.

Programmatic Use

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

To get the block parameter value programmatically, use the get_param function.

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

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

Cutoff frequency (Hz), fс — Cutoff frequency for the damped PR controller

2.5 (default) | positive scalar

Cutoff frequency for the damped PR controller, specified in hertz as a positive scalar. The block uses this value to set the half-bandwidth of the resonant peak. A smaller value produces a narrower, sharper peak that is more selective but less robust to frequency variations. Increase this value if the grid frequency fluctuates significantly.

Dependencies

This parameter is visible when Control type is set to Damped.

Programmatic Use

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

To get the block parameter value programmatically, use the get_param function.

Parameter:	CutoffFrequency
Values:	"2.5" (default) | positive scalar in quotes
Data Types:	char | string

Example: set_param(gcb,"CutoffFrequency","5")

Output data type — Data type of the controller output

single (default) | double | ...

Data type of the controller output signal. Select single (32-bit floating-point) for deployment on embedded targets where memory is constrained and single-precision arithmetic is hardware-accelerated. Select double (64-bit floating-point) for high-fidelity desktop simulation or when numerical precision is critical for loop analysis.

Programmatic Use

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

To get the block parameter value programmatically, use the get_param function.

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

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

Initial Conditions Tab

Source — Source of integrator initial conditions

Internal (default) | External

Select Internal to specify initial values for the forward-path and feedback integrators in the block parameters. The Forward path integrator and Feedback integrator parameters become visible.

Select External to provide initial conditions through signals connected directly to the integrator states. Use this mode for seamless controller handoff or bumpless transfer between operating modes.

Programmatic Use

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

To get the block parameter value programmatically, use the get_param function.

Parameter:	InitializationSource
Values:	"Internal" (default) | "External"

Example: set_param(gcb,"InitializationSource","External")

Forward path integrator — Initial condition for the forward path integrator

0 (default) | nonnegative scalar

Initial condition for the forward path integrator, specified as a nonnegative scalar. The block loads this value into the forward-path integrator state at simulation start. Set this to zero for a typical cold start or to a nonzero value to match a known operating state when initializing mid-simulation.

Dependencies

This parameter is visible when Source (initial conditions) is set to Internal.

Programmatic Use

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

To get the block parameter value programmatically, use the get_param function.

Parameter:	ForwardIntegratorInitial
Values:	"0" (default) | nonnegative scalar in quotes
Data Types:	char | string

Example: set_param(gcb,"ForwardIntegratorInitial","0.1")

Feedback integrator — Initial condition for the feedback integrator

0 (default) | nonnegative scalar

Initial condition for the feedback integrator, specified as a nonnegative scalar. The block loads this value into the feedback integrator state at simulation start. Set this to zero for a typical cold start or to a nonzero value to match a known operating state when initializing mid-simulation.

Dependencies

This parameter is visible when Source (initial conditions) is set to Internal.

Programmatic Use

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

Parameter:	FeedbackIntegratorInitial
Values:	"0" (default) | nonnegative scalar in quotes
Data Types:	char | string

Example: set_param(gcb,"FeedbackIntegratorInitial","0.1")

Limit output — Option to enable output saturation

on (default) | off

Option to enable output saturation. Select this parameter to limit the controller output to a specified value. When enabled, the output is clamped symmetrically and anti-windup logic can prevent integrator accumulation during saturation.

Programmatic Use

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

To get the block parameter value programmatically, use the get_param function.

Parameter:	LimitOutput
Values:	"on" (default) | "off"

Example: set_param(gcb,"LimitOutput","off")

Source — Source of output saturation limit

Internal (default) | External

Select Internal to specify the saturation limit in the block parameters using the Output limit parameter.

Select External to provide the saturation limit through an input signal. Use this mode when the saturation limit changes at run time, such as in applications with variable modulation index constraints.

Dependencies

This parameter is visible when Limit output is selected.

Programmatic Use

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

To get the block parameter value programmatically, use the get_param function.

Parameter:	SaturationSource
Values:	"Internal" (default) | "External"

Example: set_param(gcb,"SaturationSource","External")

Output limit — Maximum absolute value of the controller output

0 (default) | nonnegative scalar

Maximum absolute value of the controller output, specified as a nonnegative scalar. The block clamps the output to the range [−OutputLimit, +OutputLimit]. Set this to match the maximum modulation index or voltage limit of your inverter.

Dependencies

• This parameter is visible when Limit output is selected.

• This parameter is visible when Source (saturation) is set to Internal.

Programmatic Use

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

To get the block parameter value programmatically, use the get_param function.

Parameter:	OutputLimit
Values:	"0" (default) | nonnegative scalar in quotes
Data Types:	char | string

Example: set_param(gcb,"OutputLimit","10")

Anti-windup Method — Method to prevent integrator windup

none (default) | Conventional

Select none for no anti-windup protection. Use this option when the output rarely saturates or when the resonant controller dynamics are fast enough that windup does not occur during normal operation.

Select Conventional to stop integrating when the output is saturated. This prevents the integrators from accumulating error during sustained saturation events, reducing recovery time after a large transient.

Dependencies

This parameter is visible when Limit output is selected.

Programmatic Use

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

To get the block parameter value programmatically, use the get_param function.

Parameter:	AntiWindupMethod
Values:	"none" (default) | "Conventional"

Example: set_param(gcb,"AntiWindupMethod","Conventional")

Extended Capabilities

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