LimitedPI

Limited PI-controller with anti-windup and feed-forward

Diagram

Information

This information is part of the Modelica Standard Library maintained by the Modelica Association.

Proportional - Integral - controller with optional feed-forward and limitation at the output.

The integral part can be switched off to obtain a limited P-controller.

The feed-forward gain can either be constant or given by the optional input kFF.

When the output is limited, the controller cannot bring the control error to zero and the integrator will not stop integrating. To avoid this WindUp - effect, an Anti-WindUp loop is implemented: The difference between unlimited and limited output is fed back to the integrator's input.

Parameters (13)

k	Value: 1 Type: Real Description: Gain
useI	Value: true Type: Boolean Description: PI else P
Ti	Value: 1 Type: Time (s) Description: Integral time constant (T>0 required)
useFF	Value: false Type: Boolean Description: Use feed-forward?
useConstantKFF	Value: true Type: Boolean Description: Use constant feed-forward factor?
KFF	Value: 1 Type: Real Description: Feed-forward gain
constantLimits	Value: true Type: Boolean Description: Use constant limits?
symmetricLimits	Value: true Type: Boolean Description: Use symmetric limits?
yMax	Value: inf Type: Real Description: Upper limit of output
yMin	Value: -yMax Type: Real Description: Lower limit of output
initType	Value: Modelica.Blocks.Types.Init.NoInit Type: Init Description: Type of initialization (1: no init, 2: steady state, 3: initial state, 4: initial output)
x_start	Value: 0 Type: Real Description: Initial or guess value of state
y_start	Value: 0 Type: Real Description: Initial value of output

Outputs (1)

controlError	Default Value: u - u_m Type: Real Description: Control error (set point - measurement)

controlError

Default Value: u - u_m

Type: Real

Description: Control error (set point - measurement)

Connectors (7)

	u	Type: RealInput Description: Connector of Real input signal
	y	Type: RealOutput Description: Connector of Real output signal
	u_m	Type: RealInput Description: Connector of measured signal
	feedForward	Type: RealInput Description: Connector of feed-forward signal
	kFF	Type: RealInput Description: Connector of feed-forward factor
	yMaxVar	Type: RealInput Description: Connector of yMax input signal
	yMinVar	Type: RealInput Description: Connector of yMin input signal

Components (13)

	feedback	Type: Feedback
	addAntiWindup	Type: Add
	integrator	Type: Integrator
	add3	Type: Add3
	variableLimiter	Type: VariableLimiter
	addSat	Type: Feedback
	product	Type: Product
	zeroI	Type: Constant
	zeroFF	Type: Constant
	constantKFF	Type: Constant
	yMaxConst	Type: Constant
	yMinConst	Type: Constant
	gain	Type: Gain