Determining switch and diode state

The code for determining switch state is below (click on "view raw" below the code box to view the code in a new window):

	def determine_state(self, br_currents, sys_branches, sys_events):
	""" Determines the state of the switch following an event
	where the continuity of current through an inductor is
	about to be broken."""
	# Mark the position of the switch in sys_branches
	for c1 in range(len(sys_branches)):
	if csv_tuple(self.pos) in sys_branches[c1]:
	branch_pos=c1
	# Since branch current direction is by default considered
	# positive when flowing away from the starting node
	# If the branch current is negative, with the switch cathode
	# closer towards the starting node, current direction is
	# positive
	## if br_currents[branch_pos]*self.resistor<-1.0:
	## if sys_branches[branch_pos].index(self.polrty)<sys_branches[branch_pos].index(csv_tuple(self.pos)):
	## if self.status=="off" and self.control_values[0]>0.0:
	## sys_events[branch_pos]="yes"
	## self.status="on"
	# If the current direction is reverse, switch can never conduct
	if br_currents[branch_pos]<0.0:
	if sys_branches[branch_pos].index(self.polrty)>sys_branches[branch_pos].index(csv_tuple(self.pos)):
	if self.status=="on":
	sys_events[branch_pos]="yes"
	self.status="off"
	## if br_currents[branch_pos]*self.resistor>1.0:
	## if sys_branches[branch_pos].index(self.polrty)>sys_branches[branch_pos].index(csv_tuple(self.pos)):
	## if self.status=="off" and self.control_values[0]>0.0:
	## sys_events[branch_pos]="yes"
	## self.status="on"
	if br_currents[branch_pos]>0.0:
	if sys_branches[branch_pos].index(self.polrty)<sys_branches[branch_pos].index(csv_tuple(self.pos)):
	if self.status=="on":
	sys_events[branch_pos]="yes"
	self.status="off"
	# Update the value of resistance
	if self.status=="off":
	self.resistor=self.resistor_off
	else:
	self.resistor=self.resistor_on
	return

view raw determine_state.py hosted with ❤ by GitHub

The code for the determining diode state is below (click on "view raw" below the code box to view the code in a new window):

	def determine_state(self, br_currents, sys_branches, sys_events):
	""" Determines the state of the diode following an event
	where the continuity of current through an inductor is
	about to be broken."""
	# Mark the position of the diode in the branches list
	for c1 in range(len(sys_branches)):
	if csv_tuple(self.pos) in sys_branches[c1]:
	branch_pos=c1
	# Since branch current direction is by default considered
	# positive when flowing away from the starting node
	# If the branch current is negative, with the diode cathode
	# closer towards the starting node, current direction is
	# positive
	if br_currents[branch_pos]*self.resistor<-1.0:
	#if br_currents[branch_pos]<-0.03:
	if sys_branches[branch_pos].index(self.polrty)<sys_branches[branch_pos].index(csv_tuple(self.pos)):
	if self.status=="off":
	sys_events[branch_pos]="yes"
	self.status="on"
	# If current direction is reverse, diode can never conduct
	if br_currents[branch_pos]<0.0:
	if sys_branches[branch_pos].index(self.polrty)>sys_branches[branch_pos].index(csv_tuple(self.pos)):
	if self.status=="on":
	sys_events[branch_pos]="yes"
	self.status="off"
	if br_currents[branch_pos]*self.resistor>1.0:
	#if br_currents[branch_pos]>0.03:
	if sys_branches[branch_pos].index(self.polrty)>sys_branches[branch_pos].index(csv_tuple(self.pos)):
	if self.status=="off":
	sys_events[branch_pos]="yes"
	self.status="on"
	if br_currents[branch_pos]>0.0:
	if sys_branches[branch_pos].index(self.polrty)<sys_branches[branch_pos].index(csv_tuple(self.pos)):
	if self.status=="on":
	sys_events[branch_pos]="yes"
	self.status="off"
	# Update the value of resistance
	if self.status=="off":
	self.resistor=self.resistor_off
	else:
	self.resistor=self.resistor_on
	return

view raw determinestate_diode.py hosted with ❤ by GitHub

This function is called after performing nodal analysis to check if the inductor current has caused an non linear device to change state. The difference between the code for switch and diode is that a switch can only turn off during nodal analysis while a diode can both turn on and turn off. My guess is that the switch should turn on only in the update_value function. If for some reason, the switch were to turn off during the nodal analysis because the current through it was negative due to an inductor, the switch remains off and only a diode can turn on to freewheel the current.

The reason for doing this will be the next detailed blog post.