Dynamic simulation of linear electromechanical solenoids. Models transient coil currents, variable inductance $L(x)$, magnetic reluctance, return spring mechanics, and inductive kickback.
Cross-Sectional View & Magnetic Flux LinesDE-ENERGIZED
Real-Time Oscilloscope Trace
V(t) [V]
I(t) [A]
x(t) [mm]
F_m [N]
LINEAR ELECTROMECHANICS
Actuator Operation
Trigger the coil manually or select a drive mode.
DC Constant
60 %
Flyback Protection Diode
Live State Specs
Coil Voltage ($V$)0.0 V
Coil Current ($I$)0.00 A
Air Gap ($g$)10.0 mm
Magnetic Pull Force ($F_m$)0.00 N
Inductance ($L$)25.0 mH
Coil Temperature Est.25.0 °C
Physical & Coil Tuning
Adjust hardware specs to observe electromechanical tradeoffs.
24 V
600 turns
12.0 Ω
800 N/m
60 g
2.0 N
How Solenoids Work
Electromagnetic Field Creation: Electric current flowing through $N$ turns generates a magnetic field $H = \frac{N I}{l_m}$.
Reluctance & Air Gap Force: Magnetic flux preference attracts the soft iron plunger to close the high-reluctance air gap ($g$), producing non-linear force $F_m \approx \frac{(N I)^2 \mu_0 A}{2 (g + g_0)^2}$.
Back-EMF Current Dip: As the plunger accelerates, rapid inductance growth $dL/dt$ induces a opposing back-EMF voltage ($I \cdot v \cdot \frac{dL}{dx}$), creating a characteristic dip in current prior to full seal.
De-energization Kickback: Rapidly cutting off coil current causes magnetic field collapse ($V = -L \frac{di}{dt}$), creating high voltage spikes unless suppressed by a flyback diode.
Key Insight: Solenoids generate much higher force near the end of stroke (sealed air gap) than at the start. This makes them ideal for snap-action switching, hydraulic spool actuation, and mechanical latching.