RC Circuits

rc-circuit.jl

using Revise
using ModelingToolkit
using ModelingToolkitStandardLibrary.Blocks: RealInput, Step, Sine, Cosine
using ModelingToolkitStandardLibrary.Electrical
using OrdinaryDiffEq
using Plots

@parameters t

@component function ControlledSwitch(; name)
    @named n = Pin()
    @named p = Pin()
    @named u = RealInput()
    eqs = [ 0 ~ ifelse(u.u > 0.05, n.v - p.v, n.i)
            0 ~ ifelse(u.u > 0.05, n.i + p.i, p.i)
    ]
    ODESystem(eqs, t, [], []; name, systems=[p, n, u])
end

function plot_controlled_switch()
    @named vcc = Voltage()

    @named resistor = Resistor(R=1)
    @named resistor2 = Resistor(R=0.0001)
    @named resistor3 = Resistor(R=0.0001)
    @named cap = Capacitor(C=4)

    @named ground = Ground()

    @named switch1 = ControlledSwitch()
    @named control1 = Cosine(;frequency = 0.01)

    @named switch2 = ControlledSwitch()
    @named control2 = Cosine(;frequency = 0.01, phase = π)

    ps = @parameters supply_voltage=12.0

    eqs = [
        connect(vcc.p, resistor2.p)
        connect(resistor2.n, switch1.p)
        connect(switch1.n, resistor.p)
        connect(switch2.n, resistor.p)
        connect(resistor.n, cap.p)
        connect(switch2.p, resistor3.p)
        connect(vcc.n, resistor3.n, cap.n, ground.g)
        vcc.V.u ~ supply_voltage
        connect(switch1.u, control1.output)
        connect(switch2.u, control2.output)
    ]

    @named switch_sys = ODESystem(eqs, t, [], ps;
        systems = [vcc, resistor2, resistor, resistor3, switch1, switch2, cap, ground, control1, control2])
    sys = structural_simplify(switch_sys)
    prob = ODAEProblem(sys, [], (0, 200.0))
    sol = solve(prob, Tsit5())

    plot(sol, idxs = [cap.v, resistor.i, control1.output.u>0.05, control2.output.u > 0.05],
        title = "RC charging and Discharging!",
        labels = ["Capacitor Voltage(V)" "Resistor Current(A)" "Switch 1 state" "Switch 2 state"])
end

plot_controlled_switch()