Incandescent Lamp

Incandescent lamp with temperature dependent resistance

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Libraries:
Simscape / Electrical / Passive

Description

The Incandescent Lamp block models an incandescent lamp, the key characteristic of which is that the resistance increases as the filament warms up.

Under the simplifying assumption that the rate of heat loss from the filament is proportional to temperature difference to ambient, the temperature of the filament is governed by

$$k{t}_c\frac{dT}{dt}=i^{2}R-kT$$

and the filament resistance is governed by the following equation

$$R=R_0\left(1+\alpha T\right)$$

where:

• R₀ is the initial resistance at turn-on (when filament is at ambient temperature).

• T is the filament temperature relative to ambient temperature.

• α is the resistance temperature coefficient.

• t_c is the thermal time constant.

• k is the heat transfer coefficient.

• R is the filament resistance.

• i is the filament current.

There are two parameterization options:

• If you select Specify resistance values directly, the block uses values that you provide for filament resistance when on and at turn-on to determine the value for the heat transfer coefficient.

• If you select Specify currents, the block uses values that you provide for filament current when on and at turn-on to determine the value for the heat transfer coefficient.

Faults

To model a fault in the Incandescent Lamp block, in the Faults section, click the Add fault hyperlink next to the fault that you want to model. In the Add Fault window, specify the fault properties. For more information about fault modeling, see Fault Behavior Modeling and Fault Triggering.

The Incandescence Lamp block allows you to model an electrical fault as an open circuit resistance. The block can trigger fault events at a specific time. When in the open-circuit state, the lamp resistance is set to be the value of the Open-circuit resistance parameter.

Examples

Automotive Electrical System

A simplified dynamic model of an automotive electrical system. The model contains electrical, mechanical, and thermal systems, and is able to simulate the effect of engine starting on the electrical network.

• Open Script

Ports

Conserving

+ — Positive terminal

electrical

Electrical conserving port associated with the lamp positive voltage.

- — Negative terminal

electrical

Electrical conserving port associated with the lamp negative voltage.

Parameters

Resistance

Parameterization — Block parameterization

Specify resistance values directly (default) | Specify currents

Select one of the following methods for block parameterization:

• Specify resistance values directly — Provide the values for filament resistance at turn-on and when on in steady state. The block determines the value for the heat transfer coefficient based on these values. This is the default option.

• Specify currents — Provide the values for filament current at turn-on and when on in steady state. The block determines the value for the heat transfer coefficient based on these values.

Initial resistance at turn-on — Initial resistance at turn-on

0.15 Ohm (default)

The resistance seen by the external circuit when the lamp is initially turned on.

Dependencies

This parameter is visible only when you select Specify resistance values directly for the Parameterization parameter.

Steady-state resistance when on — Steady-state resistance when on

1 Ohm (default)

The resistance seen by the external circuit when the lamp is on and in steady state. This resistance should be greater than the Initial resistance at turn-on.

Dependencies

This parameter is visible only when you select Specify resistance values directly for the Parameterization parameter.

Inrush current at turn-on — Inrush current at turn-on

70 A (default)

The current through the lamp when it is initially turned on.

Dependencies

This parameter is visible only when you select Specify currents for the Parameterization parameter.

Steady-state current when on — Steady-state current when on

10 A (default)

The current through the lamp when it is on and in steady state. This current should be less than the Inrush current at turn-on.

Dependencies

This parameter is visible only when you select Specify currents for the Parameterization parameter.

Rated voltage — Lamp rated voltage

12 V (default)

The rated voltage for the lamp, and the voltage value for which the resistance or current values are provided in the on and turn-on states.

Resistance temperature coefficient — Resistance temperature coefficient

0.004 1/K (default)

The fractional increase in resistance per unit increase in temperature.

Dynamics

Thermal time constant — Thermal time constant

25 ms (default)

The first-order thermal time constant for filament temperature when the lamp is turned on or off.

Initial lamp state — Initial lamp state

Off (default) | On

Select between On and Off.

Faults

Open circuit fault — Option to add open circuit fault

Add fault (default)

Option to add an open-circuit fault in the Incandescent Lamp block.

To add a fault, click the Add fault hyperlink.

Open-circuit resistance — Open-circuit resistance

1e6 Ohm (default)

Value of the filament resistance when the lamp goes open-circuit.

Dependencies

To enable this parameter, add a fault to the Incandescent Lamp block by clicking the Add fault hyperlink in the Open circuit fault parameter.

After you create the fault, you can change the properties in the Fault Inspector window. When you open a block that has a fault, the Open Fault Inspector hyperlink appears instead of the Add fault hyperlink. For an example that shows how to include faults, see Analyze a DC Armature Winding Fault.

Trigger fault at time — Time before entering faulted state

0 s (default) | nonnegative scalar

For simulation times greater than this parameter value the filament resistance becomes equal to the Open-circuit resistance. Specifying a finite value for this parameter lets you simulate the fault dynamics when the bulb burns out.

Dependencies

To enable this parameter, in the Fault Inspector window, set Trigger Type to Timed.

This parameter appears in the Trigger section of the Fault Inspector window. For more information, see Set Fault Triggers.

Extended Capabilities

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

Version History

Introduced in R2012b