Simulation does not stop on under-/overvoltage

[DavidMStraub]

When choosing incorrect inputs or simulation settings, the simulation keeps running with voltage or temperature growing without bound.

[DavidMStraub]

Hi @milanofthe, I'm unsure what the correct pattern is in PathSim to auto-terminate simulations on specific events. Concretely, I need to stop when the voltage crosses the lower or upper cutoff voltage of the cell, as results become nonsensical outside (in real systems, the battery management system needs to ensure the thresholds are never crossed). I can use ZeroCrossingDown to define the event, but I'm not sure where to put them, as the block doesn't know about the simulation.

[milanofthe]

In the Python script you can do something like this, it sets a flag internally and exits the timestepping loop at next iteration. By the time its called Sim is already in the namespace:

#events to detect
def func_evt_1(t):
    i, o, s = VL()
    return s[0] - 4

def func_evt_2(t):
    i, o, s = VL()
    return s[1] - 4

E1 = ZeroCrossingUp(
    func_evt=func_evt_1,
    tolerance=1e-4
    )

E2 = ZeroCrossingUp(
    func_evt=func_evt_2,
    func_act=lambda _: Sim.stop(), # <--- this one 
    tolerance=1e-4
    )

E3 = ZeroCrossingDown(
    func_evt=func_evt_1,
    tolerance=1e-4
    )

E4 = ZeroCrossingDown(
    func_evt=func_evt_2,
    tolerance=1e-4
    )

#initialize simulation with the blocks, connections, timestep and logging enabled
Sim = Simulation(
    blocks, 
    connections, 
    [E1, E2, E3, E4],
    dt=dt, 
    log=True, 
    Solver=RKBS32, 
    tolerance_lte_rel=1e-4, 
    tolerance_lte_abs=1e-6
    )

A distinct Stop event might be nice to have though.

[DavidMStraub]

Somehow I think it would be nice if models/blocks could gracefully tell the running simulation to stop.

What about the following modification to PathSim:

class StopSimulation(Exception):
    pass

class Simulation:
    def _run_loop(...):
        # ...
        try:
            success, ... = self.timestep(...)
        except StopSimulation:
            self.stop()
            break

What do you think? Then certain events could just throw StopSimulation and it would bubble up to the calling simulation, without need for a reference to it.

[milanofthe]

Yes that would work. I have played with the idea of introducing more custom exceptions anyway. This would be another argument for it.

[DavidMStraub]

I could draft a PR.