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>
30 #include <Main/fg_props.hxx>
31 #include <Main/globals.hxx>
33 #include "electrical.hxx"
36 FGElectricalComponent::FGElectricalComponent() :
45 FGElectricalSupplier::FGElectricalSupplier ( SGPropertyNode *node ) {
48 // cout << "Creating a supplier" << endl;
49 name = node->getStringValue("name");
50 string _model = node->getStringValue("kind");
51 // cout << "_model = " << _model << endl;
52 if ( _model == "battery" ) {
54 amp_hours = node->getFloatValue("amp-hours", 40.0);
55 percent_remaining = node->getFloatValue("percent-remaining", 1.0);
56 charge_amps = node->getFloatValue("charge-amps", 7.0);
57 } else if ( _model == "alternator" ) {
58 model = FG_ALTERNATOR;
59 rpm_src = node->getStringValue("rpm-source");
60 rpm_threshold = node->getFloatValue("rpm-threshold", 600.0);
61 ideal_amps = node->getFloatValue("amps", 60.0);
62 } else if ( _model == "external" ) {
64 ideal_amps = node->getFloatValue("amps", 60.0);
68 ideal_volts = node->getFloatValue("volts");
71 for ( i = 0; i < node->nChildren(); ++i ) {
72 SGPropertyNode *child = node->getChild(i);
73 // cout << " scanning: " << child->getName() << endl;
74 if ( !strcmp(child->getName(), "prop") ) {
75 string prop = child->getStringValue();
76 // cout << " Adding prop = " << prop << endl;
78 fgSetFloat( prop.c_str(), ideal_amps );
82 _rpm_node = fgGetNode( rpm_src.c_str(), true);
86 float FGElectricalSupplier::apply_load( float amps, float dt ) {
87 if ( model == FG_BATTERY ) {
88 // calculate amp hours used
89 float amphrs_used = amps * dt / 3600.0;
91 // calculate percent of total available capacity
92 float percent_used = amphrs_used / amp_hours;
93 percent_remaining -= percent_used;
94 if ( percent_remaining < 0.0 ) {
95 percent_remaining = 0.0;
96 } else if ( percent_remaining > 1.0 ) {
97 percent_remaining = 1.0;
99 // cout << "battery percent = " << percent_remaining << endl;
100 return amp_hours * percent_remaining;
101 } else if ( model == FG_ALTERNATOR ) {
102 // scale alternator output for rpms < 600. For rpms >= 600
103 // give full output. This is just a WAG, and probably not how
104 // it really works but I'm keeping things "simple" to start.
105 float rpm = _rpm_node->getFloatValue();
106 float factor = rpm / rpm_threshold;
107 if ( factor > 1.0 ) {
110 // cout << "alternator amps = " << amps * factor << endl;
111 float available_amps = ideal_amps * factor;
112 return available_amps - amps;
113 } else if ( model == FG_EXTERNAL ) {
114 // cout << "external amps = " << 0.0 << endl;
115 float available_amps = ideal_amps;
116 return available_amps - amps;
118 SG_LOG( SG_ALL, SG_ALERT, "unknown supplier type" );
125 float FGElectricalSupplier::get_output_volts() {
126 if ( model == FG_BATTERY ) {
127 // cout << "battery amps = " << amps << endl;
128 float x = 1.0 - percent_remaining;
129 float tmp = -(3.0 * x - 1.0);
130 float factor = (tmp*tmp*tmp*tmp*tmp + 32) / 32;
131 // cout << "battery % = " << percent_remaining <<
132 // " factor = " << factor << endl;
133 // percent_remaining -= 0.001;
134 return ideal_volts * factor;
135 } else if ( model == FG_ALTERNATOR ) {
136 // scale alternator output for rpms < 600. For rpms >= 600
137 // give full output. This is just a WAG, and probably not how
138 // it really works but I'm keeping things "simple" to start.
139 float rpm = _rpm_node->getFloatValue();
140 float factor = rpm / rpm_threshold;
141 if ( factor > 1.0 ) {
144 // cout << "alternator amps = " << amps * factor << endl;
145 return ideal_volts * factor;
146 } else if ( model == FG_EXTERNAL ) {
147 // cout << "external amps = " << 0.0 << endl;
150 SG_LOG( SG_ALL, SG_ALERT, "unknown supplier type" );
157 float FGElectricalSupplier::get_output_amps() {
158 if ( model == FG_BATTERY ) {
159 // cout << "battery amp_hours = " << amp_hours << endl;
161 // This is a WAG, but produce enough amps to burn the entire
162 // battery in one minute.
163 return amp_hours * 60.0;
164 } else if ( model == FG_ALTERNATOR ) {
165 // scale alternator output for rpms < 600. For rpms >= 600
166 // give full output. This is just a WAG, and probably not how
167 // it really works but I'm keeping things "simple" to start.
168 float rpm = _rpm_node->getFloatValue();
169 float factor = rpm / rpm_threshold;
170 if ( factor > 1.0 ) {
173 // cout << "alternator amps = " << ideal_amps * factor << endl;
174 return ideal_amps * factor;
175 } else if ( model == FG_EXTERNAL ) {
176 // cout << "external amps = " << 0.0 << endl;
179 SG_LOG( SG_ALL, SG_ALERT, "unknown supplier type" );
186 FGElectricalBus::FGElectricalBus ( SGPropertyNode *node ) {
189 name = node->getStringValue("name");
191 for ( i = 0; i < node->nChildren(); ++i ) {
192 SGPropertyNode *child = node->getChild(i);
193 if ( !strcmp(child->getName(), "prop") ) {
194 string prop = child->getStringValue();
201 FGElectricalOutput::FGElectricalOutput ( SGPropertyNode *node ) {
203 load_amps = 0.1; // arbitrary default value
205 name = node->getStringValue("name");
206 SGPropertyNode *draw = node->getNode("rated-draw");
207 if ( draw != NULL ) {
208 load_amps = draw->getFloatValue();
210 // cout << "rated draw = " << output_amps << endl;
213 for ( i = 0; i < node->nChildren(); ++i ) {
214 SGPropertyNode *child = node->getChild(i);
215 if ( !strcmp(child->getName(), "prop") ) {
216 string prop = child->getStringValue();
223 FGElectricalSwitch::FGElectricalSwitch( SGPropertyNode *node ) :
226 circuit_breaker( false )
228 bool initial_state = true;
230 for ( i = 0; i < node->nChildren(); ++i ) {
231 SGPropertyNode *child = node->getChild(i);
232 string cname = child->getName();
233 string cval = child->getStringValue();
234 if ( cname == "prop" ) {
235 switch_node = fgGetNode( cval.c_str(), true );
236 // cout << "switch node = " << cval << endl;
237 } else if ( cname == "initial-state" ) {
238 if ( cval == "off" || cval == "false" ) {
239 initial_state = false;
241 // cout << "initial state = " << initial_state << endl;
242 } else if ( cname == "rating-amps" ) {
243 rating_amps = atof( cval.c_str() );
244 circuit_breaker = true;
245 // cout << "initial state = " << initial_state << endl;
249 switch_node->setBoolValue( initial_state );
250 // cout << " value = " << switch_node->getBoolValue() << endl;
254 FGElectricalConnector::FGElectricalConnector ( SGPropertyNode *node,
255 FGElectricalSystem *es ) {
259 for ( i = 0; i < node->nChildren(); ++i ) {
260 SGPropertyNode *child = node->getChild(i);
261 string cname = child->getName();
262 string cval = child->getStringValue();
263 // cout << " " << cname << " = " << cval << endl;
264 if ( cname == "input" ) {
265 FGElectricalComponent *s = es->find( child->getStringValue() );
268 if ( s->get_kind() == FG_SUPPLIER ) {
269 s->add_output( this );
270 } else if ( s->get_kind() == FG_BUS ) {
271 s->add_output( this );
273 SG_LOG( SG_ALL, SG_ALERT,
274 "Attempt to connect to something that can't provide an output: "
275 << child->getStringValue() );
278 SG_LOG( SG_ALL, SG_ALERT, "Can't find named source: "
279 << child->getStringValue() );
281 } else if ( cname == "output" ) {
282 FGElectricalComponent *s = es->find( child->getStringValue() );
285 if ( s->get_kind() == FG_BUS ) {
286 s->add_input( this );
287 } else if ( s->get_kind() == FG_OUTPUT ) {
288 s->add_input( this );
289 } else if ( s->get_kind() == FG_SUPPLIER &&
290 ((FGElectricalSupplier *)s)->get_model()
291 == FGElectricalSupplier::FG_BATTERY ) {
292 s->add_output( this );
294 SG_LOG( SG_ALL, SG_ALERT,
295 "Attempt to connect to something that can't provide an input: "
296 << child->getStringValue() );
299 SG_LOG( SG_ALL, SG_ALERT, "Can't find named source: "
300 << child->getStringValue() );
302 } else if ( cname == "switch" ) {
303 // cout << "Switch = " << child->getStringValue() << endl;
304 FGElectricalSwitch s( child );
311 // set all switches to the specified state
312 void FGElectricalConnector::set_switches( bool state ) {
313 // cout << "setting switch state to " << state << endl;
314 for ( unsigned int i = 0; i < switches.size(); ++i ) {
315 switches[i].set_state( state );
320 // return true if all switches are true, false otherwise. A connector
321 // could have multiple switches, but they all need to be true(closed)
322 // for current to get through.
323 bool FGElectricalConnector::get_state() {
325 for ( i = 0; i < switches.size(); ++i ) {
326 if ( ! switches[i].get_state() ) {
335 FGElectricalSystem::FGElectricalSystem ( SGPropertyNode *node ) :
342 for ( i = 0; i < node->nChildren(); ++i ) {
343 SGPropertyNode *child = node->getChild(i);
344 string cname = child->getName();
345 string cval = child->getStringValue();
346 if ( cname == "name" ) {
348 } else if ( cname == "number" ) {
349 num = child->getIntValue();
350 } else if ( cname == "path" ) {
353 SG_LOG( SG_SYSTEMS, SG_WARN,
354 "Error in electrical system config logic" );
355 if ( name.length() ) {
356 SG_LOG( SG_SYSTEMS, SG_WARN, "Section = " << name );
363 FGElectricalSystem::~FGElectricalSystem () {
367 void FGElectricalSystem::init () {
368 config_props = new SGPropertyNode;
370 _volts_out = fgGetNode( "/systems/electrical/volts", true );
371 _amps_out = fgGetNode( "/systems/electrical/amps", true );
373 // allow the electrical system to be specified via the
374 // aircraft-set.xml file (for backwards compatibility) or through
375 // the aircraft-systems.xml file. If a -set.xml entry is
376 // specified, that overrides the system entry.
377 SGPropertyNode *path_n = fgGetNode("/sim/systems/electrical/path");
379 if ( path.length() ) {
380 SG_LOG( SG_ALL, SG_INFO,
381 "NOTICE: System manager configuration specifies an " <<
382 "electrical system: " << path << " but it is " <<
383 "being overridden by the one specified in the -set.xml " <<
384 "file: " << path_n->getStringValue() );
387 path = path_n->getStringValue();
390 if ( path.length() ) {
391 SGPath config( globals->get_fg_root() );
392 config.append( path );
394 // load an obsolete xml configuration
395 SG_LOG( SG_ALL, SG_ALERT,
396 "Reading xml electrical system model from "
399 readProperties( config.str(), config_props );
404 SG_LOG( SG_ALL, SG_ALERT,
405 "Detected a logic error in the electrical system ");
406 SG_LOG( SG_ALL, SG_ALERT,
407 "specification file. See earlier errors for " );
408 SG_LOG( SG_ALL, SG_ALERT,
412 } catch (const sg_exception& exc) {
413 SG_LOG( SG_ALL, SG_ALERT,
414 "Failed to load electrical system model: "
418 SG_LOG( SG_ALL, SG_INFO,
419 "No xml-based electrical model specified for this model!");
423 _amps_out->setDoubleValue(0);
430 void FGElectricalSystem::bind () {
434 void FGElectricalSystem::unbind () {
438 void FGElectricalSystem::update (double dt) {
443 // cout << "Updating electrical system, dt = " << dt << endl;
447 // zero out the voltage before we start, but don't clear the
448 // requested load values.
449 for ( i = 0; i < suppliers.size(); ++i ) {
450 suppliers[i]->set_volts( 0.0 );
452 for ( i = 0; i < buses.size(); ++i ) {
453 buses[i]->set_volts( 0.0 );
455 for ( i = 0; i < outputs.size(); ++i ) {
456 outputs[i]->set_volts( 0.0 );
458 for ( i = 0; i < connectors.size(); ++i ) {
459 connectors[i]->set_volts( 0.0 );
462 // for each "external" supplier, propagate the electrical current
463 for ( i = 0; i < suppliers.size(); ++i ) {
464 FGElectricalSupplier *node = (FGElectricalSupplier *)suppliers[i];
465 if ( node->get_model() == FGElectricalSupplier::FG_EXTERNAL ) {
467 // cout << "Starting propagation: " << suppliers[i]->get_name()
469 load = propagate( suppliers[i], dt,
470 node->get_output_volts(),
471 node->get_output_amps(),
474 if ( node->apply_load( load, dt ) < 0.0 ) {
475 cout << "Error drawing more current than available!" << endl;
480 // for each "alternator" supplier, propagate the electrical
482 for ( i = 0; i < suppliers.size(); ++i ) {
483 FGElectricalSupplier *node = (FGElectricalSupplier *)suppliers[i];
484 if ( node->get_model() == FGElectricalSupplier::FG_ALTERNATOR) {
486 // cout << "Starting propagation: " << suppliers[i]->get_name()
488 load = propagate( suppliers[i], dt,
489 node->get_output_volts(),
490 node->get_output_amps(),
493 if ( node->apply_load( load, dt ) < 0.0 ) {
494 cout << "Error drawing more current than available!" << endl;
499 // for each "battery" supplier, propagate the electrical
501 for ( i = 0; i < suppliers.size(); ++i ) {
502 FGElectricalSupplier *node = (FGElectricalSupplier *)suppliers[i];
503 if ( node->get_model() == FGElectricalSupplier::FG_BATTERY ) {
505 // cout << "Starting propagation: " << suppliers[i]->get_name()
507 load = propagate( suppliers[i], dt,
508 node->get_output_volts(),
509 node->get_output_amps(),
511 // cout << "battery load = " << load << endl;
513 if ( node->apply_load( load, dt ) < 0.0 ) {
514 cout << "Error drawing more current than available!" << endl;
520 = fgGetFloat("/systems/electrical/suppliers/alternator") / 60.0;
522 // impliment an extremely simplistic voltage model (assumes
523 // certain naming conventions in electrical system config)
524 // FIXME: we probably want to be able to feed power from all
525 // engines if they are running and the master-alt is switched on
527 if ( fgGetBool("/controls/engines/engine[0]/master-bat") ) {
530 if ( fgGetBool("/controls/engines/engine[0]/master-alt") ) {
531 if ( fgGetFloat("/engines/engine[0]/rpm") > 800 ) {
532 float alt_contrib = 28.0;
533 if ( alt_contrib > volts ) {
536 } else if ( fgGetFloat("/engines/engine[0]/rpm") > 200 ) {
537 float alt_contrib = 20.0;
538 if ( alt_contrib > volts ) {
543 _volts_out->setFloatValue( volts );
545 // impliment an extremely simplistic amps model (assumes certain
546 // naming conventions in the electrical system config) ... FIXME:
547 // make this more generic
549 if ( fgGetBool("/controls/engines/engine[0]/master-bat") ) {
550 if ( fgGetBool("/controls/engines/engine[0]/master-alt") &&
551 fgGetFloat("/engines/engine[0]/rpm") > 800 )
553 amps += 40.0 * alt_norm;
555 amps -= 15.0; // normal load
556 if ( fgGetBool("/controls/switches/flashing-beacon") ) {
559 if ( fgGetBool("/controls/switches/nav-lights") ) {
566 _amps_out->setFloatValue( amps );
570 bool FGElectricalSystem::build () {
571 SGPropertyNode *node;
574 int count = config_props->nChildren();
575 for ( i = 0; i < count; ++i ) {
576 node = config_props->getChild(i);
577 string name = node->getName();
578 // cout << name << endl;
579 if ( name == "supplier" ) {
580 FGElectricalSupplier *s =
581 new FGElectricalSupplier( node );
582 suppliers.push_back( s );
583 } else if ( name == "bus" ) {
585 new FGElectricalBus( node );
586 buses.push_back( b );
587 } else if ( name == "output" ) {
588 FGElectricalOutput *o =
589 new FGElectricalOutput( node );
590 outputs.push_back( o );
591 } else if ( name == "connector" ) {
592 FGElectricalConnector *c =
593 new FGElectricalConnector( node, this );
594 connectors.push_back( c );
596 SG_LOG( SG_ALL, SG_ALERT, "Unknown component type specified: "
606 // propagate the electrical current through the network, returns the
607 // total current drawn by the children of this node.
608 float FGElectricalSystem::propagate( FGElectricalComponent *node, double dt,
609 float input_volts, float input_amps,
613 float total_load = 0.0;
615 // determine the current to carry forward
617 if ( !fgGetBool("/systems/electrical/serviceable") ) {
619 } else if ( node->get_kind() == FGElectricalComponent::FG_SUPPLIER ) {
620 // cout << s << "is a supplier (" << node->get_name() << ")" << endl;
621 FGElectricalSupplier *supplier = (FGElectricalSupplier *)node;
622 if ( supplier->get_model() == FGElectricalSupplier::FG_BATTERY ) {
623 // cout << s << " (and is a battery)" << endl;
624 float battery_volts = supplier->get_output_volts();
625 if ( battery_volts < (input_volts - 0.1) ) {
626 // special handling of a battery charge condition
627 // cout << s << " (and is being charged) in v = "
628 // << input_volts << " current v = " << battery_volts
630 supplier->apply_load( -supplier->get_charge_amps(), dt );
631 return supplier->get_charge_amps();
635 } else if ( node->get_kind() == FGElectricalComponent::FG_BUS ) {
636 // cout << s << "is a bus (" << node->get_name() << ")" << endl;
638 } else if ( node->get_kind() == FGElectricalComponent::FG_OUTPUT ) {
639 // cout << s << "is an output (" << node->get_name() << ")" << endl;
642 // draw current if we have voltage
643 total_load = node->get_load_amps();
645 } else if ( node->get_kind() == FGElectricalComponent::FG_CONNECTOR ) {
646 // cout << s << "is a connector (" << node->get_name() << ")" << endl;
647 if ( ((FGElectricalConnector *)node)->get_state() ) {
652 // cout << s << " input_volts = " << volts << endl;
654 SG_LOG( SG_ALL, SG_ALERT, "unkown node type" );
659 // if this node has found a stronger power source, update the
660 // value and propagate to all children
661 if ( volts > node->get_volts() ) {
662 node->set_volts( volts );
663 for ( i = 0; i < node->get_num_outputs(); ++i ) {
664 FGElectricalComponent *child = node->get_output(i);
665 // send current equal to load
666 total_load += propagate( child, dt,
667 volts, child->get_load_amps(),
671 // if not an output node, register the downstream current draw
672 // (sum of all children) with this node. If volts are zero,
673 // current draw should be zero.
674 if ( node->get_kind() != FGElectricalComponent::FG_OUTPUT ) {
675 node->set_load_amps( total_load );
678 node->set_available_amps( input_amps - total_load );
680 // publish values to specified properties
681 for ( i = 0; i < node->get_num_props(); ++i ) {
682 fgSetFloat( node->get_prop(i).c_str(), node->get_volts() );
686 cout << s << node->get_name() << " -> (volts) " << node->get_volts()
688 cout << s << node->get_name() << " -> (load amps) " << total_load
690 cout << s << node->get_name() << " -> (input amps) " << input_amps
692 cout << s << node->get_name() << " -> (extra amps) "
693 << node->get_available_amps() << endl;
698 // cout << s << "no further propagation" << endl;
704 // search for the named component and return a pointer to it, NULL otherwise
705 FGElectricalComponent *FGElectricalSystem::find ( const string &name ) {
710 for ( i = 0; i < suppliers.size(); ++i ) {
711 s = suppliers[i]->get_name();
712 // cout << " " << s << endl;
719 for ( i = 0; i < buses.size(); ++i ) {
720 s = buses[i]->get_name();
721 // cout << " " << s << endl;
727 // then search outputs
728 for ( i = 0; i < outputs.size(); ++i ) {
729 s = outputs[i]->get_name();
730 // cout << " " << s << endl;