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adapting power calculation in energy helper to use documented formula…
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…s, refs eclipse-sumo#7695
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@behrisch
behrisch committed Oct 16, 2020
1 parent 16c73f8 commit 67cf37d
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Showing 3 changed files with 27 additions and 23 deletions.
4 changes: 2 additions & 2 deletions src/microsim/devices/MSDevice_Battery.cpp
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Expand Up @@ -110,9 +110,9 @@ bool MSDevice_Battery::notifyMove(SUMOTrafficObject& tObject, double /* oldPos *
// Update Energy from the battery
if (getMaximumBatteryCapacity() != 0) {
myParam[SUMO_ATTR_ANGLE] = myLastAngle == std::numeric_limits<double>::infinity() ? 0. : GeomHelper::angleDiff(myLastAngle, veh.getAngle());
myConsum = PollutantsInterface::getEnergyHelper().compute(0, PollutantsInterface::ELEC, veh.getSpeed(), veh.getAcceleration(), veh.getSlope(), &myParam);
myConsum = PollutantsInterface::getEnergyHelper().compute(0, PollutantsInterface::ELEC, veh.getSpeed(), veh.getAcceleration(), veh.getSlope(), &myParam) * TS;
if (veh.isParking()) {
// recupration from last braking step is ok but further consumption should cease
// recuperation from last braking step is ok but further consumption should cease
myConsum = MIN2(myConsum, 0.0);
}

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2 changes: 1 addition & 1 deletion src/microsim/devices/MSDevice_ElecHybrid.cpp
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Expand Up @@ -904,7 +904,7 @@ MSDevice_ElecHybrid::acceleration(SUMOVehicle& veh, double power, double oldSpee
double
MSDevice_ElecHybrid::consumption(SUMOVehicle& veh, double a, double newSpeed) {
myParam[SUMO_ATTR_ANGLE] = ISNAN(myLastAngle) ? 0. : GeomHelper::angleDiff(myLastAngle, veh.getAngle());
return PollutantsInterface::getEnergyHelper().compute(0, PollutantsInterface::ELEC, newSpeed, a, veh.getSlope(), &myParam);
return PollutantsInterface::getEnergyHelper().compute(0, PollutantsInterface::ELEC, newSpeed, a, veh.getSlope(), &myParam) * TS;
}


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44 changes: 24 additions & 20 deletions src/utils/emissions/HelpersEnergy.cpp
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Expand Up @@ -67,28 +67,30 @@ HelpersEnergy::compute(const SUMOEmissionClass /* c */, const PollutantsInterfac
const double lastV = v - ACCEL2SPEED(a);
const double mass = param->find(SUMO_ATTR_VEHICLEMASS)->second;

// calculate potential energy difference
double energyDiff = mass * GRAVITY * sin(DEG2RAD(slope)) * SPEED2DIST(v);
// calculate power needed for potential energy difference
double power = mass * GRAVITY * sin(DEG2RAD(slope)) * v;

// kinetic energy difference of vehicle
energyDiff += 0.5 * mass * (v * v - lastV * lastV);
// power needed for kinetic energy difference of vehicle
power += 0.5 * mass * (v * v - lastV * lastV) / TS;

// add rotational energy diff of internal rotating elements
energyDiff += param->find(SUMO_ATTR_INTERNALMOMENTOFINERTIA)->second * (v * v - lastV * lastV);
// add power needed for rotational energy diff of internal rotating elements
power += 0.5 * param->find(SUMO_ATTR_INTERNALMOMENTOFINERTIA)->second * (v * v - lastV * lastV) / TS;

// Energy loss through Air resistance [Ws]
// power needed for Energy loss through Air resistance [Ws]
// Calculate energy losses:
// EnergyLoss,Air = 1/2 * rho_air [kg/m^3] * myFrontSurfaceArea [m^2] * myAirDragCoefficient [-] * v_Veh^2 [m/s] * s [m]
// ... with rho_air [kg/m^3] = 1,2041 kg/m^3 (at T = 20C)
// ... with s [m] = v_Veh [m/s] * TS [s]
energyDiff += 0.5 * 1.2041 * param->find(SUMO_ATTR_FRONTSURFACEAREA)->second * param->find(SUMO_ATTR_AIRDRAGCOEFFICIENT)->second * v * v * SPEED2DIST(v);
// divided by TS to get power instead of energy
power += 0.5 * 1.2041 * param->find(SUMO_ATTR_FRONTSURFACEAREA)->second * param->find(SUMO_ATTR_AIRDRAGCOEFFICIENT)->second * v * v * v;

// Energy loss through Roll resistance [Ws]
// power needed for Energy loss through Roll resistance [Ws]
// ... (fabs(veh.getSpeed())>=0.01) = 0, if vehicle isn't moving
// EnergyLoss,Tire = c_R [-] * F_N [N] * s [m]
// ... with c_R = ~0.012 (car tire on asphalt)
// ... with F_N [N] = myMass [kg] * g [m/s^2]
energyDiff += param->find(SUMO_ATTR_ROLLDRAGCOEFFICIENT)->second * GRAVITY * mass * SPEED2DIST(v);
// divided by TS to get power instead of energy
power += param->find(SUMO_ATTR_ROLLDRAGCOEFFICIENT)->second * GRAVITY * mass * v;

// Energy loss through friction by radial force [Ws]
// If angle of vehicle was changed
Expand All @@ -105,20 +107,21 @@ HelpersEnergy::compute(const SUMOEmissionClass /* c */, const PollutantsInterfac
}
// EnergyLoss,internalFrictionRadialForce = c [m] * F_rad [N];
// Energy loss through friction by radial force [Ws]
energyDiff += param->find(SUMO_ATTR_RADIALDRAGCOEFFICIENT)->second * mass * v * v / radius;
// divided by TS to get power instead of energy
power += param->find(SUMO_ATTR_RADIALDRAGCOEFFICIENT)->second * mass * v * v / radius * v;
}

// EnergyLoss,constantConsumers
// Energy loss through constant loads (e.g. A/C) [Ws]
energyDiff += param->find(SUMO_ATTR_CONSTANTPOWERINTAKE)->second;
// Energy loss through constant loads (e.g. A/C) [W]
power += param->find(SUMO_ATTR_CONSTANTPOWERINTAKE)->second;

// E_Bat = E_kin_pot + EnergyLoss;
if (energyDiff > 0) {
if (power > 0) {
// Assumption: Efficiency of myPropulsionEfficiency when accelerating
energyDiff /= param->find(SUMO_ATTR_PROPULSIONEFFICIENCY)->second;
power /= param->find(SUMO_ATTR_PROPULSIONEFFICIENCY)->second;
} else {
// Assumption: Efficiency of myRecuperationEfficiency when recuperating
energyDiff *= param->find(SUMO_ATTR_RECUPERATIONEFFICIENCY)->second;
power *= param->find(SUMO_ATTR_RECUPERATIONEFFICIENCY)->second;
if (a != 0) {
// Fiori, Chiara & Ahn, Kyoungho & Rakha, Hesham. (2016).
// Power-based electric vehicle energy consumption model: Model
Expand All @@ -129,14 +132,15 @@ HelpersEnergy::compute(const SUMOEmissionClass /* c */, const PollutantsInterfac
// Improving The Accuracy of The Energy Consumption Model for
// Electric Vehicle in SUMO Considering The Ambient Temperature
// Effects
energyDiff *= (1 / exp(param->find(SUMO_ATTR_RECUPERATIONEFFICIENCY_BY_DECELERATION)->second / fabs(a)));
power *= (1 / exp(param->find(SUMO_ATTR_RECUPERATIONEFFICIENCY_BY_DECELERATION)->second / fabs(a)));
}
}

// convert from [Ws], i.e. [J] to [Wh] (3600s / 1h):
return energyDiff / 3600.;
// convert from [W], to [Wh/s] (3600s / 1h):
return power / 3600.;
}


double
HelpersEnergy::acceleration(const SUMOEmissionClass /* c */, const PollutantsInterface::EmissionType e, const double v, const double P, const double slope, const std::map<int, double>* param) const {
if (e != PollutantsInterface::ELEC) {
Expand All @@ -148,7 +152,7 @@ HelpersEnergy::acceleration(const SUMOEmissionClass /* c */, const PollutantsInt
}

// Inverse formula for the function compute()
// Computes the achievable acceleartion using the given speed and amount of consumed electric power
// Computes the achievable acceleration using the given speed and amount of consumed electric power
// It does not consider loss through friction by radial force and the recuperation efficiency dependent on |a| (eta_reuperation is considered constant)
// Prest = const1*a + const2*a^2 + const3*a^3

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