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Constant Current Load (Three-Phase)

Three-phase constant current load

  • Library:
  • Simscape / Electrical / Passive

Description

The Constant Current Load (Three-Phase) block implements a constant current load for a three-phase supply.

This block consumes a current equal to the value of the Consumed current (RMS) parameter as long as the voltage from the three-phase supply is equal to or greater than the value specified for the Minimum supply voltage (phase-to-phase RMS) parameter.

When the voltage from the three-phase supply drops below the value of Minimum supply voltage (phase-to-phase RMS), the load behaviour changes and the block models a load with constant resistance.

Equations

If the three-phase voltages are balanced, the phase-to-phase RMS voltage is defined by this equation:

VlineRMS=(vavdc)2+(vbvdc)2+(vcvdc)2,

where vdc=va+vb+vc3.

The currents for each of the three phases are defined by this equation:

ik(t)=vk(t)Requiv,

where Requiv is the equivalent resistance and depends on value of the Minimum supply voltage (phase-to-phase RMS) parameter.

If the voltage from the three-phase supply is greater than the value specified for the Minimum supply voltage (phase-to-phase RMS) parameter, the equivalent resistance is defined by:

Requiv=vpk2IRMSconsumed,

where vpk is the voltage peak magnitude and IRMSconsumed is the value of the Consumed current (RMS) parameter.

If the voltage from the three-phase supply is less than the value specified for the Minimum supply voltage (phase-to-phase RMS) parameter, the equivalent resistance is defined by:

Requiv=vphRMSminIRMSconsumed,

where vphRMSmin=vlineRMSmin3 is the phase-to-ground RMS minimum voltage.

Faults

The Constant Current Load (Three-Phase) block allows you to model an electrical fault as an open circuit. The block can trigger fault events either:

  • At a specific time

  • When a power limit is exceeded for longer than a specific time interval

You can also 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.

Load-Flow Analysis

If the block is in a network that is compatible with frequency-time simulation mode, you can perform a load-flow analysis on the network. A load-flow analysis provides steady-state values that you can use to initialize a machine.

For more information, see Perform a Load-Flow Analysis Using Simscape Electrical and Frequency and Time Simulation Mode.

Ports

Conserving

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Expandable three-phase electrical port associated with the three-phase voltage.

Parameters

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Main

Root mean square current consumed by the block.

Minimum voltage, in phase-to-phase RMS, that the supply must provide for the block to act as a current load.

Faults

Select Yes to enable faults modeling and expose parameters that allow you to select the reporting method and specify the trigger mechanism.

Conductance during the open-circuit state.

Dependencies

To enable this parameter, set Enable open-circuit fault to Yes.

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.

Dependencies

To enable this parameter, set Enable open-circuit fault to Yes.

Whether to trigger the fault based on temporal or behavioral conditions.

Dependencies

To enable this parameter, set Enable open-circuit fault to Yes.

Simulation time when the block enters the faulted state.

Dependencies

To enable this parameter, set Enable open-circuit fault to Yes and Fault trigger to Temporal.

Maximum permissible power value. If the power exceeds this value for longer than the Time to fail when exceeding power parameter value, then the block enters the faulted state.

Dependencies

To enable this parameter, set Enable open-circuit fault to Yes and Fault trigger to Behavioral.

Maximum length of time that the power can exceed the maximum permissible value without triggering the fault.

Dependencies

To enable this parameter, set Enable open-circuit fault to Yes and Fault trigger to Behavioral.

Extended Capabilities

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

Introduced in R2021a