PFC Voltage Controller

R2026b

Regulate DC bus voltage in a power factor correction boost converter

Since R2026b

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PFC Voltage Controller block

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

Description

The PFC Voltage Controller block implements a discrete-time PI controller for the outer voltage loop of a power factor correction (PFC) boost converter. The block computes a current demand by comparing a DC bus voltage reference to the measured DC bus voltage, using PI gains supplied through the CtrlParams input bus from a PFC Controller Gains block.

The block computes the voltage error as the difference between the reference at V_Ref and the measured voltage at V_Fb, and applies the PI controller to produce a current demand at I_Out. In a cascaded PFC control structure, multiply this output by the absolute value of the normalized grid voltage sine wave (|sinθ_Vin|) and connect the result to the I_Ref input of a PFC Current Controller block to achieve unity power factor operation.

The block supports bumpless transfer through the Rst and I_Out^Init ports. When Rst is nonzero, the block sets the current demand output to the value at I_Out^Init and preloads the integrator state so the output resumes from that value when you release the reset. Use I_Out^UpperLimit and I_Out^LowerLimit to clamp the current demand and protect the converter from overcurrent during startup or transients.

To use this block, connect the CtrlParams output of a PFC Controller Gains block configured for the same converter specifications. Connect a DC bus voltage reference to V_Ref and the measured DC bus voltage to V_Fb. Multiply the I_Out output by |sinθ_Vin| and connect the result to the I_Ref input of a PFC Current Controller block.

Examples

Design and Simulate Boost PFC Controllers

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

• Open Live Script

Ports

Input

V_Ref — DC bus voltage reference signal

scalar

Desired DC bus output voltage setpoint in volts, specified as a scalar. The block computes the voltage error as the difference between this reference and the V_Fb feedback signal.

Data Types: double | single

V_Fb — Measured DC bus voltage feedback

scalar

Measured DC bus voltage in volts, specified as a scalar. Connect this port to a voltage sensor output in your model.

Data Types: double | single

CtrlParams — Discrete-time PI controller gain parameters

bus

Controller gain parameters bus containing the discrete-time voltage 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 I_Out^Init.

Data Types: double | single

I_Out^Init — Initial current demand value at reset

scalar

Initial output current demand applied when Rst is asserted, specified as a scalar. This value preloads the integrator state for bumpless transfer after a reset event.

Data Types: double | single

I_Out^UpperLimit — Upper saturation limit for the current demand output

scalar

Maximum allowed current demand output in amperes, specified as a scalar. Set this to the maximum peak inductor current amplitude to protect the converter from overcurrent during transients and startup.

Data Types: double | single

I_Out^LowerLimit — Lower saturation limit for the current demand output

scalar

Minimum allowed current demand output in amperes, specified as a scalar. Typically set to zero or a small positive value to prevent negative current demand in a unidirectional PFC stage.

Data Types: double | single

Output

I_Out — Current demand for the inner current control loop

scalar

Current demand output in the range [I_Out^LowerLimit, I_Out^UpperLimit], returned as a scalar. In a cascaded controller structure, multiply this signal by |sinθ_Vin| (the absolute value of the normalized grid voltage) and connect the result to the I_Ref input of a PFC Current Controller block to achieve unity power factor operation.

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 current demand reaches I_Out^UpperLimit or I_Out^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