Summary

So far, we have analyzed the case where a constant-current power supply is connected to the coil. Here, we analyze the case where a constant-voltage power supply (power supply given a voltage waveform) is connected to the coil. We also show how to continue the previous calculation by restarting.

Explanation

The model here is the same as the model used in “Static magnetic field analysis using ELMCUR (element current source)". A voltage is applied to that coil by a constant voltage power supply to excite the coil. This problem is linear with no eddy currents and is expressed as a concentrated constant circuit. Therefore, we do not normally perform this type of analysis, but we will run it as an example. The files pre_geom2D.neu and 2D_to_3D are identical. A constant voltage of 100V is given in the input.1 file. Assume that an external resistor of 5 Ω is connected to the coil. The current value of the coil at each time is output in output.

Next, the voltage of the power supply drops to zero at 0.1 second to simulate a short-circuit condition; rename the solutions file created in the first run to old_solutions and restart with the input.2 file as input. The coil current value is output to the output file even after restarting. The current waveform is plotted as shown in Fig. 1. The one based on the circuit calculation is the time variation obtained analytically from the resistance and inductance. They are in good agreement.

Fig.1　Time variation of coil current