Fault

Electrical fault with temporal, behavioral, or external trigger

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Libraries:
Simscape / Electrical / Utilities

Description

The Fault block allows you to represent an electrical fault as an instantaneous change in resistance. You can use it to replicate both open-circuit and short-circuit fault behaviors. The block can trigger fault events:

• At a specific time. The block can also stop imposing a temporal fault after a specified time duration.

• When a predefined voltage range or current range is exceeded

• When an external trigger signal goes high or low

Optionally, the external trigger option also permits the fault to reset when the trigger signal reverts. You can enable or disable all three trigger mechanisms separately. If more than one trigger mechanism is required in a simulation, you can use them together.

When no fault is triggered, the resistance between the two electrical ports is defined by the Unfaulted resistance parameter value. The default value for this parameter is inf ohms, that is the ports are open-circuit. When a fault is triggered, the block changes the resistance between the two electrical ports to the Faulted resistance value. The default value for this parameter is 1e-3 ohms, that is the ports are short-circuited.

You can choose whether to issue an assertion when a fault occurs, by using the Reporting when a fault occurs parameter. The assertion can take the form of a warning or an error. By default, the block does not issue an assertion.

The physical output X represents the fault state; if the block is faulted, the output is 1, otherwise, it is 0. The physical signal input F is the external fault trigger signal and is used only if Enable external fault trigger is set to Yes.

Examples

MOSFET Fault in Buck Converter

How a fault may be applied to a MOSFET in a power converter in order to explore the operation of protection circuitry. After the MOSFET becomes faulted, the crowbar circuitry is activated in order to clamp the output voltage across the load and eventually to cause the fuse to blow.

Open Model

Ports

Input

F — External fault trigger signal

physical

Physical signal input port associated with the external fault trigger signal.

Output

X — Fault state

physical

Physical signal output port associated with the fault state. It outputs 1 if the block is faulted, 0 otherwise.

Conserving

+ — Positive terminal

electrical

Electrical conserving port associated with the fault positive terminal.

- — Negative terminal

electrical

Electrical conserving port associated with the fault negative terminal.

Parameters

Main

Unfaulted resistance — Resistance with no fault

inf Ohm (default)

Resistance between the + and – ports when there is no fault.

Faulted resistance — Resistance with fault

1e-3 Ohm (default)

Resistance between the + and – ports when the block is in the faulted state.

Reporting when a fault occurs — Fault occurrence report

None (default) | Warn | Error

Choose whether to issue an assertion when a fault occurs:

• None — The block does not issue an assertion.

• Warn — The block issues a warning.

• Error — Simulation stops with an error.

Temporal Trigger

Enable temporal fault trigger — Temporal fault trigger option

No (default) | Yes

Select Yes to enable time-based fault triggering.

Simulation time for fault event — Simulation time for fault event

1 s (default)

Set the simulation time that the block enters the fault state.

Dependencies

This parameter is visible only when you set the Enable temporal fault trigger parameter to Yes.

Fault duration — Duration time for the fault

inf s (default)

Set the simulation duration time for the fault. The block exits the fault state when the duration time is over.

Dependencies

This parameter is visible only when you set the Enable temporal fault trigger parameter to Yes.

Behavioral Trigger

Enable behavioral fault trigger — Behavioral fault trigger option

No (default) | Yes

Select Yes to enable behavioral fault triggering.

Permissible voltage range — Permissible voltage range

[-100, 100] V (default)

Specify a vector of length 2 that defines the permissible voltage range. If the voltage is outside this range for longer than the Time to fail when exceeding voltage range parameter value, then the block enters the fault state.

Dependencies

This parameter is visible only when you set the Enable behavioral fault trigger parameter to Yes.

Time to fail when exceeding voltage range — Time to fail when exceeding voltage range

1 s (default)

Set the maximum length of time that the voltage can be outside the permissible voltage range without triggering the fault.

Dependencies

This parameter is visible only when you set the Enable behavioral fault trigger parameter to Yes.

Permissible current range — Permissible current range

[-1, 1] A (default)

Specify a vector of length 2 that defines the permissible current range. If the current is outside this range for longer than the Time to fail when exceeding current range parameter value, then the block enters the fault state.

Dependencies

This parameter is visible only when you set the Enable behavioral fault trigger parameter to Yes.

Time to fail when exceeding current range — Time to fail when exceeding current range

1 s (default)

Set the maximum length of time that the current can be outside the permissible current range without triggering the fault.

Dependencies

This parameter is visible only when you set the Enable behavioral fault trigger parameter to Yes.

External Trigger

Enable external fault trigger — External fault trigger option

No (default) | Yes

Select Yes to enable external fault triggering. The physical signal input F provides the external fault trigger signal.

External fault trigger — External fault trigger condition

Faulted if F >= Fault threshold (default) | Faulted if F <= Fault threshold

Choose the fault condition:

• Faulted if F >= Fault threshold — The fault occurs when the external signal value becomes greater than, or equal to, the Fault threshold parameter value.

• Faulted if F <= Fault threshold — The fault occurs when the external signal value becomes less than, or equal to, the Fault threshold parameter value.

Dependencies

This parameter is visible only when you set the Enable external fault trigger parameter to Yes.

Fault threshold — Fault threshold

0.5 (default)

The threshold value that triggers the fault when the external signal crosses it in the direction, specified by the fault condition.

Dependencies

This parameter is visible only when you set the Enable external fault trigger parameter to Yes.

Fault resets when fault trigger reverts — Fault resets when fault trigger reverts

No (default) | Yes

Select Yes to have the fault reset when the trigger signal reverts.

Dependencies

This parameter is visible only when you set the Enable external fault trigger parameter to Yes.

Extended Capabilities

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

Version History

Introduced in R2015b