BIPOLAR ALTERNATIVE TO H BRIDGE - GENERATING SINE WAVEFORMS - HALF / SINGLE & FULL

[Carl-NC]

Does anybody have a good suggestion how to simulate the ground?

The best way I can think of is to add a core material to the TX coil. Easy-Spice lets you define a saturable core for inductors and transformers that I assume produces a B-H curve. That's the key to simulating anything in the ferrous quadrant as the B-H curve gap determines the loss angle. You can't do it with just an RL model. Not sure if LT-Spice supports cores.

Another possibility is to use an analog behavioral model. However, it still needs a way to sense the TX magnetic field and produce a ground magnetic response, so it would need to look something like this:


f(x) can be a LaPlace transform or a simple analog behavioral block, I think both are supported by LT-Spice. This model can also support iron targets and even non-ferrous targets.

[Teleno]

Not sure if LT-Spice supports cores.

Here are some LTSpice examples. They look intimidating.

https://ltwiki.org/index.php?title=The_Chan_model

https://electronics.stackexchange.com/questions/243927/transformer-with-hysteresis-in-ltspice

Models that should work on all SPICE based programs.

http://www.intusoft.com/articles/satcore.pdf

[Tinkerer]

Thank you, Carl and Teleno, for the help with simulating the ground. I am afraid that your suggestions are beyond my capabilities.

In the meantime, in the simulation, I mimicked the losses of coil energy due to the ground by adding losses in the RX. This causes the slope of the TX current to increase.
The losses in the ground also reduce the peak TX current. Changing the height of the coil above the ground increases or decreases the losses.

With a traditional PI, at each cycle the coil is totally discharged and fully recharged.
With the Square wave current TX, the losses in the targets and the ground, accumulate.

The only solution is the replace the losses at each cycle.

Here is the effect of the TX slope shown on the RX. (Real circuit) The red trace is a target.
Sampling this RX signal, AC coupling to the integrator works, but reduces the amount of gain possible in the preamp. It also complicates the Ground Balance a lot.

[Aziz]

Hi all,

this TX circuit is awesome.

I like it. Thanks Moodz for sharing it.