1 // electrical.cxx - a flexible, generic electrical system model.
3 // Written by Curtis Olson, started September 2002.
5 // Copyright (C) 2002 Curtis L. Olson - http://www.flightgear.org/~curt
7 // This program is free software; you can redistribute it and/or
8 // modify it under the terms of the GNU General Public License as
9 // published by the Free Software Foundation; either version 2 of the
10 // License, or (at your option) any later version.
12 // This program is distributed in the hope that it will be useful, but
13 // WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 // General Public License for more details.
17 // You should have received a copy of the GNU General Public License
18 // along with this program; if not, write to the Free Software
19 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
27 #include <simgear/structure/exception.hxx>
28 #include <simgear/misc/sg_path.hxx>
29 #include <simgear/debug/logstream.hxx>
30 #include <simgear/props/props_io.hxx>
32 #include <Main/fg_props.hxx>
33 #include <Main/globals.hxx>
35 #include "electrical.hxx"
38 FGElectricalComponent::FGElectricalComponent() :
47 FGElectricalSupplier::FGElectricalSupplier ( SGPropertyNode *node ) {
50 // cout << "Creating a supplier" << endl;
51 name = node->getStringValue("name");
52 string _model = node->getStringValue("kind");
53 // cout << "_model = " << _model << endl;
54 if ( _model == "battery" ) {
56 amp_hours = node->getFloatValue("amp-hours", 40.0);
57 percent_remaining = node->getFloatValue("percent-remaining", 1.0);
58 charge_amps = node->getFloatValue("charge-amps", 7.0);
59 } else if ( _model == "alternator" ) {
60 model = FG_ALTERNATOR;
61 rpm_src = node->getStringValue("rpm-source");
62 rpm_threshold = node->getFloatValue("rpm-threshold", 600.0);
63 ideal_amps = node->getFloatValue("amps", 60.0);
64 } else if ( _model == "external" ) {
66 ideal_amps = node->getFloatValue("amps", 60.0);
70 ideal_volts = node->getFloatValue("volts");
73 for ( i = 0; i < node->nChildren(); ++i ) {
74 SGPropertyNode *child = node->getChild(i);
75 // cout << " scanning: " << child->getName() << endl;
76 if ( !strcmp(child->getName(), "prop") ) {
77 string prop = child->getStringValue();
78 // cout << " Adding prop = " << prop << endl;
80 fgSetFloat( prop.c_str(), ideal_amps );
84 _rpm_node = fgGetNode( rpm_src.c_str(), true);
88 float FGElectricalSupplier::apply_load( float amps, float dt ) {
89 if ( model == FG_BATTERY ) {
90 // calculate amp hours used
91 float amphrs_used = amps * dt / 3600.0;
93 // calculate percent of total available capacity
94 float percent_used = amphrs_used / amp_hours;
95 percent_remaining -= percent_used;
96 if ( percent_remaining < 0.0 ) {
97 percent_remaining = 0.0;
98 } else if ( percent_remaining > 1.0 ) {
99 percent_remaining = 1.0;
101 // cout << "battery percent = " << percent_remaining << endl;
102 return amp_hours * percent_remaining;
103 } else if ( model == FG_ALTERNATOR ) {
104 // scale alternator output for rpms < 600. For rpms >= 600
105 // give full output. This is just a WAG, and probably not how
106 // it really works but I'm keeping things "simple" to start.
107 float rpm = _rpm_node->getFloatValue();
108 float factor = rpm / rpm_threshold;
109 if ( factor > 1.0 ) {
112 // cout << "alternator amps = " << amps * factor << endl;
113 float available_amps = ideal_amps * factor;
114 return available_amps - amps;
115 } else if ( model == FG_EXTERNAL ) {
116 // cout << "external amps = " << 0.0 << endl;
117 float available_amps = ideal_amps;
118 return available_amps - amps;
120 SG_LOG( SG_ALL, SG_ALERT, "unknown supplier type" );
127 float FGElectricalSupplier::get_output_volts() {
128 if ( model == FG_BATTERY ) {
129 // cout << "battery amps = " << amps << endl;
130 float x = 1.0 - percent_remaining;
131 float tmp = -(3.0 * x - 1.0);
132 float factor = (tmp*tmp*tmp*tmp*tmp + 32) / 32;
133 // cout << "battery % = " << percent_remaining <<
134 // " factor = " << factor << endl;
135 // percent_remaining -= 0.001;
136 return ideal_volts * factor;
137 } else if ( model == FG_ALTERNATOR ) {
138 // scale alternator output for rpms < 600. For rpms >= 600
139 // give full output. This is just a WAG, and probably not how
140 // it really works but I'm keeping things "simple" to start.
141 float rpm = _rpm_node->getFloatValue();
142 float factor = rpm / rpm_threshold;
143 if ( factor > 1.0 ) {
146 // cout << "alternator amps = " << amps * factor << endl;
147 return ideal_volts * factor;
148 } else if ( model == FG_EXTERNAL ) {
149 // cout << "external amps = " << 0.0 << endl;
152 SG_LOG( SG_ALL, SG_ALERT, "unknown supplier type" );
159 float FGElectricalSupplier::get_output_amps() {
160 if ( model == FG_BATTERY ) {
161 // cout << "battery amp_hours = " << amp_hours << endl;
163 // This is a WAG, but produce enough amps to burn the entire
164 // battery in one minute.
165 return amp_hours * 60.0;
166 } else if ( model == FG_ALTERNATOR ) {
167 // scale alternator output for rpms < 600. For rpms >= 600
168 // give full output. This is just a WAG, and probably not how
169 // it really works but I'm keeping things "simple" to start.
170 float rpm = _rpm_node->getFloatValue();
171 float factor = rpm / rpm_threshold;
172 if ( factor > 1.0 ) {
175 // cout << "alternator amps = " << ideal_amps * factor << endl;
176 return ideal_amps * factor;
177 } else if ( model == FG_EXTERNAL ) {
178 // cout << "external amps = " << 0.0 << endl;
181 SG_LOG( SG_ALL, SG_ALERT, "unknown supplier type" );
188 FGElectricalBus::FGElectricalBus ( SGPropertyNode *node ) {
191 name = node->getStringValue("name");
193 for ( i = 0; i < node->nChildren(); ++i ) {
194 SGPropertyNode *child = node->getChild(i);
195 if ( !strcmp(child->getName(), "prop") ) {
196 string prop = child->getStringValue();
203 FGElectricalOutput::FGElectricalOutput ( SGPropertyNode *node ) {
205 load_amps = 0.1; // arbitrary default value
207 name = node->getStringValue("name");
208 SGPropertyNode *draw = node->getNode("rated-draw");
209 if ( draw != NULL ) {
210 load_amps = draw->getFloatValue();
212 // cout << "rated draw = " << output_amps << endl;
215 for ( i = 0; i < node->nChildren(); ++i ) {
216 SGPropertyNode *child = node->getChild(i);
217 if ( !strcmp(child->getName(), "prop") ) {
218 string prop = child->getStringValue();
225 FGElectricalSwitch::FGElectricalSwitch( SGPropertyNode *node ) :
228 circuit_breaker( false )
230 bool initial_state = true;
232 for ( i = 0; i < node->nChildren(); ++i ) {
233 SGPropertyNode *child = node->getChild(i);
234 string cname = child->getName();
235 string cval = child->getStringValue();
236 if ( cname == "prop" ) {
237 switch_node = fgGetNode( cval.c_str(), true );
238 // cout << "switch node = " << cval << endl;
239 } else if ( cname == "initial-state" ) {
240 if ( cval == "off" || cval == "false" ) {
241 initial_state = false;
243 // cout << "initial state = " << initial_state << endl;
244 } else if ( cname == "rating-amps" ) {
245 rating_amps = atof( cval.c_str() );
246 circuit_breaker = true;
247 // cout << "initial state = " << initial_state << endl;
251 switch_node->setBoolValue( initial_state );
252 // cout << " value = " << switch_node->getBoolValue() << endl;
256 FGElectricalConnector::FGElectricalConnector ( SGPropertyNode *node,
257 FGElectricalSystem *es ) {
261 for ( i = 0; i < node->nChildren(); ++i ) {
262 SGPropertyNode *child = node->getChild(i);
263 string cname = child->getName();
264 string cval = child->getStringValue();
265 // cout << " " << cname << " = " << cval << endl;
266 if ( cname == "input" ) {
267 FGElectricalComponent *s = es->find( child->getStringValue() );
270 if ( s->get_kind() == FG_SUPPLIER ) {
271 s->add_output( this );
272 } else if ( s->get_kind() == FG_BUS ) {
273 s->add_output( this );
275 SG_LOG( SG_ALL, SG_ALERT,
276 "Attempt to connect to something that can't provide an output: "
277 << child->getStringValue() );
280 SG_LOG( SG_ALL, SG_ALERT, "Can't find named source: "
281 << child->getStringValue() );
283 } else if ( cname == "output" ) {
284 FGElectricalComponent *s = es->find( child->getStringValue() );
287 if ( s->get_kind() == FG_BUS ) {
288 s->add_input( this );
289 } else if ( s->get_kind() == FG_OUTPUT ) {
290 s->add_input( this );
291 } else if ( s->get_kind() == FG_SUPPLIER &&
292 ((FGElectricalSupplier *)s)->get_model()
293 == FGElectricalSupplier::FG_BATTERY ) {
294 s->add_output( this );
296 SG_LOG( SG_ALL, SG_ALERT,
297 "Attempt to connect to something that can't provide an input: "
298 << child->getStringValue() );
301 SG_LOG( SG_ALL, SG_ALERT, "Can't find named source: "
302 << child->getStringValue() );
304 } else if ( cname == "switch" ) {
305 // cout << "Switch = " << child->getStringValue() << endl;
306 FGElectricalSwitch s( child );
313 // set all switches to the specified state
314 void FGElectricalConnector::set_switches( bool state ) {
315 // cout << "setting switch state to " << state << endl;
316 for ( unsigned int i = 0; i < switches.size(); ++i ) {
317 switches[i].set_state( state );
322 // return true if all switches are true, false otherwise. A connector
323 // could have multiple switches, but they all need to be true(closed)
324 // for current to get through.
325 bool FGElectricalConnector::get_state() {
327 for ( i = 0; i < switches.size(); ++i ) {
328 if ( ! switches[i].get_state() ) {
337 FGElectricalSystem::FGElectricalSystem ( SGPropertyNode *node ) :
338 name(node->getStringValue("name", "electrical")),
339 num(node->getIntValue("number", 0)),
340 path(node->getStringValue("path")),
346 FGElectricalSystem::~FGElectricalSystem () {
350 void FGElectricalSystem::init () {
351 config_props = new SGPropertyNode;
353 _volts_out = fgGetNode( "/systems/electrical/volts", true );
354 _amps_out = fgGetNode( "/systems/electrical/amps", true );
356 // allow the electrical system to be specified via the
357 // aircraft-set.xml file (for backwards compatibility) or through
358 // the aircraft-systems.xml file. If a -set.xml entry is
359 // specified, that overrides the system entry.
360 SGPropertyNode *path_n = fgGetNode("/sim/systems/electrical/path");
362 if ( path.length() ) {
363 SG_LOG( SG_ALL, SG_INFO,
364 "NOTICE: System manager configuration specifies an " <<
365 "electrical system: " << path << " but it is " <<
366 "being overridden by the one specified in the -set.xml " <<
367 "file: " << path_n->getStringValue() );
370 path = path_n->getStringValue();
373 if ( path.length() ) {
374 SGPath config( globals->get_fg_root() );
375 config.append( path );
377 // load an obsolete xml configuration
378 SG_LOG( SG_ALL, SG_WARN,
379 "Reading deprecated xml electrical system model from\n "
382 readProperties( config.str(), config_props );
387 SG_LOG( SG_ALL, SG_ALERT,
388 "Detected a logic error in the electrical system ");
389 SG_LOG( SG_ALL, SG_ALERT,
390 "specification file. See earlier errors for " );
391 SG_LOG( SG_ALL, SG_ALERT,
395 } catch (const sg_exception& exc) {
396 SG_LOG( SG_ALL, SG_ALERT,
397 "Failed to load electrical system model: "
401 SG_LOG( SG_ALL, SG_INFO,
402 "No xml-based electrical model specified for this model!");
406 _amps_out->setDoubleValue(0);
413 void FGElectricalSystem::bind () {
417 void FGElectricalSystem::unbind () {
421 void FGElectricalSystem::update (double dt) {
426 // cout << "Updating electrical system, dt = " << dt << endl;
430 // zero out the voltage before we start, but don't clear the
431 // requested load values.
432 for ( i = 0; i < suppliers.size(); ++i ) {
433 suppliers[i]->set_volts( 0.0 );
435 for ( i = 0; i < buses.size(); ++i ) {
436 buses[i]->set_volts( 0.0 );
438 for ( i = 0; i < outputs.size(); ++i ) {
439 outputs[i]->set_volts( 0.0 );
441 for ( i = 0; i < connectors.size(); ++i ) {
442 connectors[i]->set_volts( 0.0 );
445 // for each "external" supplier, propagate the electrical current
446 for ( i = 0; i < suppliers.size(); ++i ) {
447 FGElectricalSupplier *node = (FGElectricalSupplier *)suppliers[i];
448 if ( node->get_model() == FGElectricalSupplier::FG_EXTERNAL ) {
450 // cout << "Starting propagation: " << suppliers[i]->get_name()
452 load = propagate( suppliers[i], dt,
453 node->get_output_volts(),
454 node->get_output_amps(),
457 if ( node->apply_load( load, dt ) < 0.0 ) {
458 SG_LOG(SG_ALL, SG_ALERT,
459 "Error drawing more current than available!");
464 // for each "alternator" supplier, propagate the electrical
466 for ( i = 0; i < suppliers.size(); ++i ) {
467 FGElectricalSupplier *node = (FGElectricalSupplier *)suppliers[i];
468 if ( node->get_model() == FGElectricalSupplier::FG_ALTERNATOR) {
470 // cout << "Starting propagation: " << suppliers[i]->get_name()
472 load = propagate( suppliers[i], dt,
473 node->get_output_volts(),
474 node->get_output_amps(),
477 if ( node->apply_load( load, dt ) < 0.0 ) {
478 SG_LOG(SG_ALL, SG_ALERT,
479 "Error drawing more current than available!");
484 // for each "battery" supplier, propagate the electrical
486 for ( i = 0; i < suppliers.size(); ++i ) {
487 FGElectricalSupplier *node = (FGElectricalSupplier *)suppliers[i];
488 if ( node->get_model() == FGElectricalSupplier::FG_BATTERY ) {
490 // cout << "Starting propagation: " << suppliers[i]->get_name()
492 load = propagate( suppliers[i], dt,
493 node->get_output_volts(),
494 node->get_output_amps(),
496 // cout << "battery load = " << load << endl;
498 if ( node->apply_load( load, dt ) < 0.0 ) {
499 SG_LOG(SG_ALL, SG_ALERT,
500 "Error drawing more current than available!");
506 = fgGetFloat("/systems/electrical/suppliers/alternator") / 60.0;
508 // impliment an extremely simplistic voltage model (assumes
509 // certain naming conventions in electrical system config)
510 // FIXME: we probably want to be able to feed power from all
511 // engines if they are running and the master-alt is switched on
513 if ( fgGetBool("/controls/engines/engine[0]/master-bat") ) {
516 if ( fgGetBool("/controls/engines/engine[0]/master-alt") ) {
517 if ( fgGetFloat("/engines/engine[0]/rpm") > 800 ) {
518 float alt_contrib = 28.0;
519 if ( alt_contrib > volts ) {
522 } else if ( fgGetFloat("/engines/engine[0]/rpm") > 200 ) {
523 float alt_contrib = 20.0;
524 if ( alt_contrib > volts ) {
529 _volts_out->setFloatValue( volts );
531 // impliment an extremely simplistic amps model (assumes certain
532 // naming conventions in the electrical system config) ... FIXME:
533 // make this more generic
535 if ( fgGetBool("/controls/engines/engine[0]/master-bat") ) {
536 if ( fgGetBool("/controls/engines/engine[0]/master-alt") &&
537 fgGetFloat("/engines/engine[0]/rpm") > 800 )
539 amps += 40.0 * alt_norm;
541 amps -= 15.0; // normal load
542 if ( fgGetBool("/controls/switches/flashing-beacon") ) {
545 if ( fgGetBool("/controls/switches/nav-lights") ) {
552 _amps_out->setFloatValue( amps );
556 bool FGElectricalSystem::build () {
557 SGPropertyNode *node;
560 int count = config_props->nChildren();
561 for ( i = 0; i < count; ++i ) {
562 node = config_props->getChild(i);
563 string name = node->getName();
564 // cout << name << endl;
565 if ( name == "supplier" ) {
566 FGElectricalSupplier *s =
567 new FGElectricalSupplier( node );
568 suppliers.push_back( s );
569 } else if ( name == "bus" ) {
571 new FGElectricalBus( node );
572 buses.push_back( b );
573 } else if ( name == "output" ) {
574 FGElectricalOutput *o =
575 new FGElectricalOutput( node );
576 outputs.push_back( o );
577 } else if ( name == "connector" ) {
578 FGElectricalConnector *c =
579 new FGElectricalConnector( node, this );
580 connectors.push_back( c );
582 SG_LOG( SG_ALL, SG_ALERT, "Unknown component type specified: "
592 // propagate the electrical current through the network, returns the
593 // total current drawn by the children of this node.
594 float FGElectricalSystem::propagate( FGElectricalComponent *node, double dt,
595 float input_volts, float input_amps,
599 float total_load = 0.0;
601 // determine the current to carry forward
603 if ( !fgGetBool("/systems/electrical/serviceable") ) {
605 } else if ( node->get_kind() == FGElectricalComponent::FG_SUPPLIER ) {
606 // cout << s << "is a supplier (" << node->get_name() << ")" << endl;
607 FGElectricalSupplier *supplier = (FGElectricalSupplier *)node;
608 if ( supplier->get_model() == FGElectricalSupplier::FG_BATTERY ) {
609 // cout << s << " (and is a battery)" << endl;
610 float battery_volts = supplier->get_output_volts();
611 if ( battery_volts < (input_volts - 0.1) ) {
612 // special handling of a battery charge condition
613 // cout << s << " (and is being charged) in v = "
614 // << input_volts << " current v = " << battery_volts
616 supplier->apply_load( -supplier->get_charge_amps(), dt );
617 return supplier->get_charge_amps();
621 } else if ( node->get_kind() == FGElectricalComponent::FG_BUS ) {
622 // cout << s << "is a bus (" << node->get_name() << ")" << endl;
624 } else if ( node->get_kind() == FGElectricalComponent::FG_OUTPUT ) {
625 // cout << s << "is an output (" << node->get_name() << ")" << endl;
628 // draw current if we have voltage
629 total_load = node->get_load_amps();
631 } else if ( node->get_kind() == FGElectricalComponent::FG_CONNECTOR ) {
632 // cout << s << "is a connector (" << node->get_name() << ")" << endl;
633 if ( ((FGElectricalConnector *)node)->get_state() ) {
638 // cout << s << " input_volts = " << volts << endl;
640 SG_LOG( SG_ALL, SG_ALERT, "unkown node type" );
645 // if this node has found a stronger power source, update the
646 // value and propagate to all children
647 if ( volts > node->get_volts() ) {
648 node->set_volts( volts );
649 for ( i = 0; i < node->get_num_outputs(); ++i ) {
650 FGElectricalComponent *child = node->get_output(i);
651 // send current equal to load
652 total_load += propagate( child, dt,
653 volts, child->get_load_amps(),
657 // if not an output node, register the downstream current draw
658 // (sum of all children) with this node. If volts are zero,
659 // current draw should be zero.
660 if ( node->get_kind() != FGElectricalComponent::FG_OUTPUT ) {
661 node->set_load_amps( total_load );
664 node->set_available_amps( input_amps - total_load );
666 // publish values to specified properties
667 for ( i = 0; i < node->get_num_props(); ++i ) {
668 fgSetFloat( node->get_prop(i).c_str(), node->get_volts() );
672 cout << s << node->get_name() << " -> (volts) " << node->get_volts()
674 cout << s << node->get_name() << " -> (load amps) " << total_load
676 cout << s << node->get_name() << " -> (input amps) " << input_amps
678 cout << s << node->get_name() << " -> (extra amps) "
679 << node->get_available_amps() << endl;
684 // cout << s << "no further propagation" << endl;
690 // search for the named component and return a pointer to it, NULL otherwise
691 FGElectricalComponent *FGElectricalSystem::find ( const string &name ) {
696 for ( i = 0; i < suppliers.size(); ++i ) {
697 s = suppliers[i]->get_name();
698 // cout << " " << s << endl;
705 for ( i = 0; i < buses.size(); ++i ) {
706 s = buses[i]->get_name();
707 // cout << " " << s << endl;
713 // then search outputs
714 for ( i = 0; i < outputs.size(); ++i ) {
715 s = outputs[i]->get_name();
716 // cout << " " << s << endl;