## Electronics

#### Want to capture the effect of dv/dt on electric field

• arshiah
Subscriber

I am trying to capture the effect of change in voltage transient on electric field in Maxwell simulations. For example, if I have different square waveforms at 10kHz switching frequency (at same duty cycle) with different dv/dt.

Let us say,

Case 1: 10kV/ms,

Case 2: 20kV/ms and

Case 3: 30kV/ms and I am using Maxwell circuit editor to generate trapezoidal excitations for the cable.

But see I can only use Maxwell circuit editor if I use a Magnetic transient solver. Am I right. Is there a way I can use Maxwell circuit editor with AC conduction electric solver?

As per my understanding, I can use Maxwell circuit editor with Magnetic transient solver. So, I am plotting the magnetic field in a cable insulation using Magnetic transient simulation with varying dv/dt. But I obtained the same magnitude of Maximum B value in all 3 cases.

Question 1: Is there any other way to capture the effect of dv/dt on B field / E field?

Question 2: Is there a way I can capture/plot the E field from Magnetic transient simulations?

On Maxwell help, I see that the equation used in time dependent magnetic transient solver type does not include a dv/dt term but rather a dA/dt term. So, I need help figuring out if Ansys understands and can simulate the effect of dv/dt on E field.

• arshiah
Subscriber
• HDLI
Ansys Employee

Generally, magnetic field solvers will calculate B field, and electric field will calculate E field in Maxwell. Only eddy current solver is full wave solution to get both B and E field in frequency domain.
I suggest you to use the 3D electric field transient solver for this simulation with the trapezoidal excitations, not magnetic transient solver. After that, you can plot the E field with time in the points, that you draw, and calculate dv/dt.
For the question shown above, it is for the magnetic transient solver and A is magnetic vector potential for B field. Thanks.
HDLI
• arshiah
Subscriber
thank you for directing me to the right person.
Thank you for your reply. Could you please suggest how to simulate "3D electric field transient solver for this simulation with the trapezoidal excitations" Is there a tutorial or a course on Ansys Learning Hub that talks about this? Could you please share the resources and point me in the right direction?

How can I define user defined excitations like trapezoidal, square and arbitary waveforms of different shapeson 3D electric field transient solver?
• arshiah
Subscriber
could you please take a look at it, and answer this question when you get a chance?
Thank you
• Navya C
Ansys Employee

Following are the ways you can define custom waveform.
1)If you can represent your waveform in equation form - You can write an equation in the voltage definition window.
2) You can create an external circuit that can generate the desired waveform for the windings.
You can define an external circuit as explained below, make sure you have the same name for the inductors in the circuit as given in the excitation.
Right-click on excitation>external circuit> edit external circuit.
Select create a circuit on the pop window.
Create your external circuit and export the netlist.
Come back to maxwell design Right-click on excitation>external circuit>edit external circuit.
Select import circuit netlist on the popup window and you are done.
Refer Mawell help for additional information on the external circuit.
3) You can also represent the waveform using a pwl function as explained in the below forum discussion
Variable Time Step in Ansys Maxwell Transient Setup ÔÇö Ansys Learning Forum

Regards Navya
• arshiah
Subscriber
Thank you for your reply. I am able to solve for B field using these steps.
But I want to plot Electric field in insulation in a motor using different wave shapes of motor excitations (like trapezoidal, stepwise etc). I will need to use Electric - AC conduction solver.
Option1: If you can represent your waveform in equation form - You can write an equation in the voltage definition window.
Can I define piecewise functions in equations? As per my experience, I did not find a way to add piecewise functions as excitation in Electric - AC conduction solver. So, I cannot use option 1.
Option2: Create an external circuit that can generate the desired waveform for the windings.
This is only possible in Magnetic transient solver.
But, I want to simulate for external circuits in Electric - AC conduction solver, so I can plot Electric field. Ansys does not allow to create external circuit in Electric - AC conduction solver, I cannot use it.
Option3: You can also represent the waveform using a pwl function as explained in the below forum discussion
This option also works only with Magnetic transient solver. But I want to plot Electric field in the machine.

Could you please help me figure out a way to plot Electric field in insulation in a motor using different wave shapes of motor excitations (like trapezoidal, stepwise etc)? Thank you.
• Navya C
Ansys Employee

Have you tried "3D electric field transient solver" as suggested by HDLI in the above post?
You should be using 3D electric field transient solver for your purpose and you can use the PWL function in this solver.
Please revisit the response provided by
Regards Navya

• arshiah
Subscriber
thank you for your reply. I wanted to give you a heads-up that I am trying this approach. I shall update you if I solve this issue using 3D electric transient solver.

• abe2122
Subscriber
I think I'm also in a similar situation. I need to use the transient magnetic solver to model eddy currents induced by a moving magnet, but I also want to model resulting electric fields/capacitive effects in my geometry too. It looks like only the eddy current solver allows us to model both magnetic and electric fields (or tweak BOTH permittivity and permeability values), but since I need motion, this isn't an option. Is there a way around this that you can see? Also is there a reason why this something like this isn't supported?