# -*- coding: utf-8 -*-
#
# Copyright 2015-2019 European Commission (JRC);
# Licensed under the EUPL (the 'Licence');
# You may not use this work except in compliance with the Licence.
# You may obtain a copy of the Licence at: http://ec.europa.eu/idabc/eupl
"""
Functions and `dsp` model to model the starter.
"""
import numpy as np
import schedula as sh
from co2mpas.defaults import dfl
dsp = sh.BlueDispatcher(
name='Starter',
description='Models the starter (motor downstream the engine).'
)
dsp.add_data('starter_efficiency', dfl.values.starter_efficiency)
dsp.add_data('delta_time_engine_starter', dfl.values.delta_time_engine_starter)
[docs]@sh.add_function(dsp, outputs=['start_demand_function'])
def define_engine_start_demand_function(engine_moment_inertia):
"""
Define the energy required to start the engine function [kJ].
:param engine_moment_inertia:
Engine moment of inertia [kg*m2].
:type engine_moment_inertia: float
:return:
Energy required to start the engine function.
:rtype: function
"""
coef = (np.pi / 30) ** 2 / 2000 * engine_moment_inertia
def _func(start_engine_speed):
return coef * start_engine_speed ** 2
return _func
[docs]@sh.add_function(dsp, outputs=['starter_powers'])
def calculate_starter_powers(
start_demand_function, times, on_engine, delta_time_engine_starter,
engine_speeds_out):
"""
Calculates starter power [kW].
:param start_demand_function:
Energy required to start the engine function.
:type start_demand_function: function
:param times:
Time vector.
:type times: numpy.array
:param on_engine:
If the engine is on [-].
:type on_engine: numpy.array
:param delta_time_engine_starter:
Time elapsed to turn on the engine with electric starter [s].
:type delta_time_engine_starter: float
:param engine_speeds_out:
Engine speed [RPM].
:type engine_speeds_out: numpy.array
:return:
Starter power [kW].
:rtype: numpy.array
"""
i = np.where(np.bitwise_xor(on_engine[:-1], on_engine[1:]))[0]
start = on_engine[i + 1]
j = np.searchsorted(times, times[i] + delta_time_engine_starter + dfl.EPS)
e = start_demand_function(engine_speeds_out[i + start.astype(int)])
e /= (times.take(j, mode='clip') - times[i])
e[~start] *= -1
p = np.zeros_like(times, float)
for i, j, e in zip(i, j, e):
p[i:j] += e
return p
[docs]@sh.add_function(dsp, outputs=['starter_electric_powers'])
def calculate_starter_electric_powers(starter_powers, starter_efficiency):
"""
Calculates starter electric power [kW].
:param starter_powers:
Starter power [kW].
:type starter_powers: numpy.array | float
:param starter_efficiency:
Starter efficiency [-].
:type starter_efficiency: float
:return:
Starter electric power [kW].
:rtype: numpy.array | float
"""
eff = starter_efficiency
return starter_powers * np.where(starter_powers <= 0, eff, 1 / eff)
[docs]@sh.add_function(dsp, outputs=['starter_currents'])
def calculate_starter_currents(
starter_electric_powers, starter_nominal_voltage):
"""
Calculates starter currents [A].
:param starter_electric_powers:
Starter electric power [kW].
:type starter_electric_powers: numpy.array | float
:param starter_nominal_voltage:
Starter nominal voltage [V].
:type starter_nominal_voltage: float
:return:
Starter currents [A].
:rtype: numpy.array | float
"""
from .alternator import calculate_alternator_currents as func
return func(starter_electric_powers, starter_nominal_voltage)
# noinspection PyMissingOrEmptyDocstring
[docs]class StarterModel:
[docs] def __init__(self, start_demand_function, starter_nominal_voltage,
starter_efficiency, delta_time_engine_starter):
self.power_demand = start_demand_function
self.nominal_voltage = starter_nominal_voltage
self.efficiency = starter_efficiency
self.time = delta_time_engine_starter
def __call__(self, start_engine_speed):
return calculate_starter_electric_powers(
self.power_demand(start_engine_speed), self.efficiency
)
[docs]@sh.add_function(dsp, outputs=['starter_model'])
def define_starter_model(
start_demand_function, starter_nominal_voltage, starter_efficiency,
delta_time_engine_starter):
"""
Defines the starter model.
:param start_demand_function:
Energy required to start the engine function.
:type start_demand_function: function
:param starter_nominal_voltage:
Starter nominal voltage [V].
:type starter_nominal_voltage: float
:param starter_efficiency:
Starter efficiency [-].
:type starter_efficiency: float
:param delta_time_engine_starter:
Time elapsed to turn on the engine with electric starter [s].
:type delta_time_engine_starter: float
:return:
Starter model.
:rtype: StarterModel
"""
return StarterModel(
start_demand_function, starter_nominal_voltage, starter_efficiency,
delta_time_engine_starter
)
