Hello

I have two modules: module_A and module_B that are inductively coupled.
In each module I declare:
- 2 electrical outputs (from coil of this module to one of another module, in order to calculate in another module fraction of voltage, related to mutual inductance)
- 2 electrical inputs (form coil of another module, in order to calculate in this module fraction of voltage, related to mutual inductance).
- ground node (in module_A it coinsides with one of the coil nodes, in module_B - not.

In top-level testbench I instantiate module_A and module_B and do the necessary connections between modules,
but don't declare ground node.

The signal source is in module_A)

The simulation results are strange: at coil outputs of module_A there is no signal (both outputs are equal to zero) as if both outputs were grounded.
When I deconnect module_A coil outputs from corresponding inputs of module_B, the signal at module_A coil outputs does present.

What could be the "right" connection strategy of 2 inductively coupled modules.

Thanks in advance.

Pavel.

Geoffrey, thank you for your response.
Here is shorted part of my code:

module_A:
Code:

module_A (COIL1, COIL2, COIL1_ext, COIL2_ext);
output COIL1, COIL2;
input COIL1_ext, COIL2_ext, node_read;
electrical COIL1, COIL2;
electrical COIL1_ext, COIL2_ext;

analog begin

	dOut_int = ddt(I(COIL1, node_read));
	dOut_ext = ddt(I(COIL1_ext, COIL2_ext));

	V(COIL1, node_read) <+ l_ant_reader * dOut_int + M * dOut_ext;

end

endmodule
 

module_B:
Code:

module_A (COIL1, COIL2, COIL1_ext, COIL2_ext);
output COIL1, COIL2;
input COIL1_ext, COIL2_ext;
electrical COIL1, COIL2;
electrical COIL1_ext, COIL2_ext;

analog begin

	dOut_int = ddt(I(COIL1, node_tag));
	dOut_ext = ddt(I(COIL1_ext, COIL2_ext));

	V(COIL1, node_tag) <+ l_ant_tag * dOut_int + M * dOut_ext;

end

endmodule
 

Assembly
Code:

module_TOP ();
ground gnd;
module_A U1 (.COIL1(coil1_A), .COIL2(gnd), .COIL1_ext(coil1_B), .COIL2_ext(gnd));
module_B U2 (.COIL1(coil1_B), .COIL2(gnd), .COIL1_ext(coil1_A), .COIL2_ext(gnd));
endmodule 

For simplicity I didn't show signal source (in module_A) and some other circuitry in modules A and B,
concentrating only on inductive coupling.

I also changed ground strategy, declaring ground only in TOP module.
This changement didn't resolve the problem.

Signal coil1_A as well as COIL1 output of module_A are at 0. When I deconnect module_B they return to "normal".

Regards.

Pavel.