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ISIS PROTEUS: why are my simulations running too slow?

MechaMark314

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Good evening everybody. This is my first post here.
The thing is that I'm trying to simulate a buck DC-DC converter using a IR2112 MOSFET driver, two IRF530 n-channel power MOSFETs, and several other components as shown in the picture attached below. As the control signal, I'm simulating the signal (which may come from a microcontroller) using a 100 kHz PULSE voltage with a duty cycle of 50%, in order to step 35 V down to 17.5 V on the output. However, once I start running the simulation this does it so painfully slow it takes several minutes just to reach about 500 miliseconds. And this is not the first time I'm experiencing this issue while simulating an electronic circuit in ISIS Proteus, since I've also done simulations for other circuits (e.g. microcontrollers, function generators, PID controllers, etc) and they have the same issue, and sometimes I get other errors, such as the feared Timestep too small... or Gmin stepping failed, or the simulation thread has been terminated. I don't know how to tackle that, and it's frustrating that sometimes this happens with even so simple circuits, yet the highly complex samples that ISIS Proteus comes with (e.g. the notorious chess game with the AVR and graphical LCD) run like a charm and with no issues. Any general tips for simulating faster and reliable in Proteus?
PROTEU.png

My laptop specs are:

ACER NITRO AN515-42
AMD Ryzen 5 2500U with Radeon Vega Mobile Gfx 2.00 GHz
8.00 GB of RAM
64-bit operating system (Windows 10), x64-based processor.
 

KlausST

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Hi,

Missing VS connection....


Klaus
 

andre_teprom

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You did not provide simulation settings, there are configuration values optimized for speed or accuracy.
 

BradtheRad

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Simplify your circuit. Omit control circuitry (left half of your schematic). Omit Q1.
Simplify to a raw buck converter powered by a clock signal. 35V pulsed DC.

Where you presently have Q2, put a diode pointing upward in standard fashion.

See if the simulation goes quickly and smoothly. Later add components. Such as Q1, with clock signal driving it through R1 D2.

High-side Nmos needs bias voltage greater than its supply voltage. Your control IC has only a 12V supply. Is that a bootstrap capacitor? 2X voltage multiplier? 3X?
Q1 needs bias greater than 35V. You might be better off changing it to a P device, biased via N device.
 

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