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Re: Coupling vs secondary voltage chart



Original poster: "Antonio Carlos M. de Queiroz" <acmdq@xxxxxxxxxx>

Tesla list wrote:
Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>
Hi Antonio,
The problem I ran into was knowing "NewVin" in the case of a primary current controlled DRSSTC. In order to know NewVin, I would have to know NewIprimary ( Xo[4}(t+dt) ) which I will not have until the simulation cycle ends. The NewVin is controlled by the primary current NewIpri. When the cycle starts, I don't know what NewIpri will be.
So I set the NewVin equal to the LastVin. This will cause Vin to actually switch one cycle later. But that really is the case in a real DRSSTC since the electronics take time to switch.

The problem is not in the calculation of Vin based on the last calculated current. I agree that this is a reasonable approach. The problem is that by always using Vin+Vin, at each transition a sum that should be zero goes to a full sum. Consider what this means, in a transition from -Vin to +Vin at t0+dt: Vin(t0)+Vin(t0+dt) should be 0. You are using 2*Vin, what is equivalent to say that Vin(t0+dt)=2*Vin. Continuing, Vin(t0+dt)+Vin(t0+2*dt)=2*Vin means that Vin(t0+2*dt)=0 Continuing, Vin(t0+2*dt)+Vin(t0+3*dt)=2*Vin means that Vin(t0+3*dt)=2*Vin. The input voltage is then oscillating between 0 and 2*Vin at each step. The oscillation gets worse at each transition. This has little effect in the simulation, however, as the high-frequency component is rejected by the relatively narrowband circuit (and by the simulation method).

Antonio Carlos M. de Queiroz