// EO-1 Reference Model v1.0: the electrical power subsystem only, in SysML v2 textual notation.
// EO-1 Reference Model v1.0 by Holarch, Angry Pixie Electronics LLC (https://holarch.app/reference-models/eo-1/)
// is licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0):
// https://creativecommons.org/licenses/by/4.0/. You may share and adapt it for any purpose, also commercially,
// if you give appropriate credit ("Holarch, Angry Pixie Electronics LLC"), link to the license and say if you
// made changes. EO-1 is a fictional spacecraft; names, people and results in the model are invented. The license
// covers the model files only, not the Holarch software.

package CubeSatEPS {
  doc /* The electrical power system (EPS) of the EO-1 CubeSat: solar arrays, a battery pack and a power distribution unit that feed the payload camera and the S-band transmitter. */

  private import ScalarValues::*;
  private import ISQ::*;
  private import SI::*;

  // ---- Ports and interfaces ----
  port def DCPowerPort {
    out attribute voltage : ElectricPotentialValue;
    out attribute current : ElectricCurrentValue;
  }

  port def BusPowerPort {
    out attribute voltage : ElectricPotentialValue;
    out attribute powerLimit : PowerValue;
  }

  interface def BusLink {
    end source : BusPowerPort;
    end load : ~BusPowerPort;
  }

  // ---- Components ----
  part def SolarArray {
    attribute mass : MassValue;
    attribute cellArea : AreaValue;
    attribute cellEfficiency : Real;
    attribute peakPower : PowerValue;
    attribute pathEfficiency : Real;
    port arrayOut : DCPowerPort;
  }

  part def BatteryPack {
    attribute mass : MassValue;
    attribute capacity : EnergyValue;
    port cellsOut : DCPowerPort;
  }

  part def PowerDistributionUnit {
    attribute mass : MassValue;
    attribute busVoltage : ElectricPotentialValue;
    port arrayIn : ~DCPowerPort;
    port batteryIn : ~DCPowerPort;
    port busOut : BusPowerPort;
  }

  part def PayloadCamera {
    attribute powerDraw : PowerValue;
    port powerIn : ~BusPowerPort;
  }

  part def SBandTransmitter {
    attribute powerDraw : PowerValue;
    port powerIn : ~BusPowerPort;
  }

  // ---- Calculations ----
  calc def OrbitAverage {
    doc /* Orbit-average array output (EQ-1.3): peak power times the sunlit fraction times the power path efficiency. */
    in peakPower : PowerValue;
    in sunlitFraction : Real;
    in pathEfficiency : Real;
    return : PowerValue = peakPower * sunlitFraction * pathEfficiency;
  }

  // ---- The assembly ----
  part def ElectricalPowerSystem {
    part solarArrays : SolarArray {
      attribute redefines mass = 0.45 [kg];
      attribute redefines cellArea = 0.2 [m^2];
      attribute redefines cellEfficiency = 0.295;
      attribute redefines peakPower = 75.4 [W];
      attribute redefines pathEfficiency = 0.6;
    }
    part battery : BatteryPack {
      attribute redefines mass = 0.62 [kg];
      attribute redefines capacity = 77 [W*h];
    }
    part pdu : PowerDistributionUnit {
      attribute redefines mass = 0.28 [kg];
      attribute redefines busVoltage = 12 [V];
    }
    port bus : BusPowerPort;

    connect solarArrays.arrayOut to pdu.arrayIn;
    connect battery.cellsOut to pdu.batteryIn;
    bind bus = pdu.busOut;

    attribute sunlitFraction : Real = 0.62;
    attribute eclipseEnergy : EnergyValue = 18.5 [W*h];
    attribute orbitAveragePower : PowerValue = OrbitAverage(solarArrays.peakPower, sunlitFraction, solarArrays.pathEfficiency);
    attribute depthOfDischarge : Real = eclipseEnergy / battery.capacity;
    attribute totalMass : MassValue = solarArrays.mass + battery.mass + pdu.mass;
  }

  part def Spacecraft {
    part eps : ElectricalPowerSystem;
    part camera : PayloadCamera {
      attribute redefines powerDraw = 6.2 [W];
    }
    part transmitter : SBandTransmitter {
      attribute redefines powerDraw = 3.4 [W];
    }

    interface payloadPower : BusLink connect eps.bus to camera.powerIn;
    interface radioPower : BusLink connect eps.bus to transmitter.powerIn;
  }

  // ---- Behavior ----
  item def Sunlight;
  item def ArrayPower;
  item def ChargePower;
  item def DischargePower;
  item def BusPower;

  action def ConvertSunlight {
    in item sun : Sunlight;
    out item power : ArrayPower;
  }

  action def ChargeBattery {
    in item power : ArrayPower;
    out item charge : ChargePower;
  }

  action def StoreEnergy {
    in item charge : ChargePower;
    out item discharge : DischargePower;
  }

  action def SupplyBus {
    in item discharge : DischargePower;
    out item bus : BusPower;
  }

  action def RunPowerCycle {
    doc /* One orbit: about 59 minutes of sunlight, then a 36 minute eclipse. */

    action collect : ConvertSunlight;
    action charge : ChargeBattery;
    action store : StoreEnergy;
    action supply : SupplyBus;

    flow collect.power to charge.power;
    flow charge.charge to store.charge;
    flow store.discharge to supply.discharge;

    first start then collect;
    first collect then charge;
    first charge then store;
    first store then supply;
    first supply then done;
  }

  part eo1 : Spacecraft {
    part redefines eps {
      perform action powerCycle : RunPowerCycle;
      part redefines solarArrays { perform powerCycle.collect; }
      part redefines battery { perform powerCycle.store; }
      part redefines pdu {
        perform powerCycle.charge;
        perform powerCycle.supply;
      }
    }
  }
}

package CubeSatEPSRequirements {
  doc /* Electrical power requirements of EO-1 (section 3) and how one of them is verified. */

  private import CubeSatEPS::*;
  private import ScalarValues::*;
  private import ISQ::*;
  private import SI::*;

  requirement def <'3.1'> OrbitAveragePower {
    doc /* The solar arrays shall generate at least 28 W orbit-average power at end of life. */
    subject eps : ElectricalPowerSystem;
    attribute required : PowerValue;
    require constraint { eps.orbitAveragePower >= required }
  }

  requirement def <'3.2'> BatteryCapacity {
    doc /* The battery shall store at least 77 Wh at beginning of life. */
    subject eps : ElectricalPowerSystem;
    attribute minimum : EnergyValue;
    require constraint { eps.battery.capacity >= minimum }
  }

  requirement def <'3.3'> DepthOfDischarge {
    doc /* The EPS shall limit battery depth of discharge to 30% per orbit. */
    subject eps : ElectricalPowerSystem;
    attribute limit : Real;
    require constraint { eps.depthOfDischarge <= limit }
  }

  requirement powerSpec {
    doc /* The electrical power requirements EO-1 is built to. */
    subject eps : ElectricalPowerSystem;
    requirement orbitAveragePower : OrbitAveragePower {
      attribute redefines required = 28 [W];
    }
    requirement batteryCapacity : BatteryCapacity {
      attribute redefines minimum = 77 [W*h];
    }
    requirement depthOfDischarge : DepthOfDischarge {
      attribute redefines limit = 0.3;
    }
  }

  satisfy powerSpec by eo1.eps;

  verification def <'TC-07'> BatteryCapacityTest {
    doc /* Discharge the pack at C/2 from full charge in a thermal chamber at 20 degrees C and measure the energy delivered. */
    subject eps : ElectricalPowerSystem;
    objective {
      verify powerSpec.batteryCapacity;
    }
    return verdict : Boolean = eps.battery.capacity >= powerSpec.batteryCapacity.minimum;
  }

  verification batteryTest : BatteryCapacityTest {
    subject eps = eo1.eps;
  }
}

package CubeSatEPSViews {
  doc /* Views of the EO-1 power system. Each view selects part of the model; the layout belongs to the tool. */

  private import CubeSatEPS::*;
  private import CubeSatEPSRequirements::*;
  private import StandardViewDefinitions::*;

  // The EPS parts, their ports and connections.
  view epsConnections : InterconnectionView {
    expose CubeSatEPS::ElectricalPowerSystem;
  }

  // One orbit: the sunlit steps, the eclipse steps and the power that flows between them.
  view powerCycleFlow : ActionFlowView {
    expose CubeSatEPS::RunPowerCycle;
  }

  // The requirements with what satisfies and verifies them.
  view requirementTree : GeneralView {
    filter @SysML::RequirementDefinition or @SysML::RequirementUsage or @SysML::SatisfyRequirementUsage;
    expose CubeSatEPSRequirements::**;
  }
}