Power sensor

Instantaneous power: current path pc→nc, voltage across pv–nv.

  • signal
  • electrical
  • Modelica Standard Library
  • 5 ports
BlockPower sensorKindpowerSensorLibraryElectrical

Description

Measures instantaneous electrical power as the product of a branch current and a voltage. The current path goes in series through pc and nc; the voltage is sensed between pv and nv.

Example

Battery, supercapacitor, and a heating load A battery cell heats a temperature-dependent resistor while a power sensor measures it, and a supercapacitor charges at 1 A.

Cell 4.2 VPowerHeater 4 ΩBody 100 J/KBody temperatureGroundSupercap 1 FCharger 1 Av supercapGround (supercap)
In Gradara, select a Power sensor block and press F1, then choose Open example. It opens as a new model in My models, ready to run.

Also in this example:Voltage sensorGroundHeat capacitorTemperature sensorResistor (thermal)DC currentBatterySupercapacitor

Ports

Outputs 1

  • Ppowersignal · W

    Instantaneous power, in watts.

Conserving terminals 4

  • i+pcelectrical

    Current path in. Current into pc is counted as positive.

  • i−ncelectrical

    Current path out. Held at the same voltage as pc.

  • v+pvelectrical

    Positive voltage-sensing pin. Draws no current.

  • v−nvelectrical

    Negative voltage-sensing pin. Draws no current.

Equations

Modelica
pc.v = nc.v, pc.i + nc.i = 0
pv.i = nv.i = 0
power = pc.i · (pv.v − nv.v)

Implementation

Modelica Standard Library 4.1.0Modelica.Electrical.Analog.Sensors.PowerSensor
MSL documentation

Assumptions and limitations

  • Instantaneous value only; for average power, filter or integrate the output.

Tips

  • To measure the power taken by a load, put pc–nc in series with it and connect pv and nv across it.

See also

Select a block in Gradara and press F1 to open its page offline.