PFC Current Controller

R2026b

Regulate inductor current in a power factor correction boost converter

Since R2026b

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PFC Current Controller block

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Libraries:
Power Converter Control with Motor Control Blockset / Control / Power Factor Correction

Description

The PFC Current Controller block implements a discrete-time PI controller for the inner current loop of a power factor correction (PFC) boost converter. The block computes a PWM duty cycle by comparing a sinusoidal current reference to the measured inductor current, using PI gains supplied through the CtrlParams input bus from a PFC Controller Gains block.

The block computes the current error as the difference between the reference at I_Ref and the measured inductor current at I_Fb, and applies the PI controller to produce a duty cycle command at Duty. To enable unity power factor operation, connect the |sinθ_Vin| input to the absolute value of the normalized grid voltage sine wave. In a cascaded PFC structure, derive I_Ref by multiplying the I_Out output of a PFC Voltage Controller block by |sinθ_Vin|.

The block supports bumpless transfer through the Rst and Duty^Init ports. When Rst is nonzero, the block sets the duty cycle output to the value at Duty^Init and preloads the integrator state so the output resumes from that duty cycle when you release the reset. Use Duty^UpperLimit and Duty^LowerLimit to clamp the duty cycle and protect the converter from excessive switch stress.

To use this block, connect the CtrlParams output of a PFC Controller Gains block configured for the same converter specifications. Connect the sinusoidal current reference to I_Ref, the measured inductor current to I_Fb, and the normalized grid sine to |sinθ_Vin|. Connect the Duty output to the duty cycle input of a PWM generation block in your converter model.

Examples

Design and Simulate Boost PFC Controllers

Design and simulation power factor correction (PFC) control for Boost converter.

• Open Live Script

Ports

Input

I_Ref — Inductor current reference signal

scalar

Desired inductor current setpoint in amperes, specified as a scalar. In a typical PFC application, compute this by multiplying the output of the PFC Voltage Controller by the normalized grid voltage shape (|sinθ_Vin|), so that the inductor current tracks a sinusoid in phase with the grid voltage.

Data Types: double | single

I_Fb — Measured inductor current feedback

scalar

Measured boost inductor current in amperes, specified as a scalar. Connect this port to a current sensor output in your model. The controller subtracts this value from I_Ref to compute the current error.

Data Types: double | single

|sinθ_Vin| — Absolute value of normalized grid voltage sine wave

scalar

Absolute value of the normalized AC grid voltage sine wave, in the range [0, 1], specified as a scalar. Multiplying the current demand from the voltage loop by this signal produces a sinusoidal current reference for unity power factor operation. Obtain this signal from a PLL block tracking the grid phase angle.

Data Types: double | single

CtrlParams — Discrete-time PI controller gain parameters

bus

Controller gain parameters bus containing the discrete-time current controller PI gains, specified as a bus. Connect the CtrlParams output of a PFC Controller Gains block.

Data Types: bus

Rst — Integrator reset trigger

scalar

Boolean signal that resets the integrator state when asserted (nonzero), specified as a scalar. When reset occurs, the output is set to the value at Duty^Init.

Data Types: double | single

Duty^Init — Initial duty cycle value at reset

scalar

Initial output duty cycle applied when Rst is asserted, specified as a scalar in the range [0, 1]. This value preloads the integrator for bumpless transfer after a reset event.

Data Types: double | single

Duty^UpperLimit — Upper saturation limit for the duty cycle output

scalar

Maximum allowed duty cycle, specified as a scalar in the range [0, 1]. The block clamps the output to this value when the computed duty cycle exceeds it.

Data Types: double | single

Duty^LowerLimit — Lower saturation limit for the duty cycle output

scalar

Minimum allowed duty cycle, specified as a scalar in the range [0, 1]. The block clamps the output to this value when the computed duty cycle falls below it.

Data Types: double | single

Output

Duty — Computed duty cycle command for the PFC boost switch

scalar

Duty cycle command in the range [Duty^LowerLimit, Duty^UpperLimit], returned as a scalar. Connect this signal to the duty cycle input of a PWM generation block to drive the PFC boost converter switch.

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.

Anti-Windup Method — Strategy to prevent integrator windup during output saturation

Clamping (default) | None | Back-calculation

Specifies how the block limits the integrator when the output duty cycle reaches Duty^UpperLimit or Duty^LowerLimit.

Select Clamping (default) to stop integration when the output is at a limit and the integrator input has the same sign as the accumulated value. This method prevents further windup without requiring an additional coefficient.

Select None to disable anti-windup. The integrator continues to accumulate during saturation.

Select Back-calculation to feed back the difference between the unsaturated and saturated output to the integrator input, scaled by the Back-Calculation Coefficient (Kb). This method unwinds the integrator while the output is saturated.

Programmatic Use

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

Parameter:	antiwindup
Values:	"Clamping" (default) | "None" | "Back-calculation"

Example: set_param(gcb,"antiwindup","Back-calculation")

Back-Calculation Coefficient (Kb) — Gain for the back-calculation anti-windup feedback path

1 (default) | positive scalar

Gain for the back-calculation anti-windup loop, specified as a positive scalar. The block uses this value to scale the feedback correction applied to the integrator state when the output saturates. Larger values cause the integrator to unwind faster after saturation. A typical starting value is 1. Increase it if you observe slow recovery after transient events that cause output saturation.

Dependencies

This parameter is visible when Anti-Windup Method is set to Back-calculation.

Programmatic Use

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

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

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

Extended Capabilities

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

Version History

Introduced in R2026b