PWM Control of dc converters

[ee01akk]

Does anyone know how to design a PWM controller with an error amplifier etc as I want to simulate it in PSpice but it said that the circuit is too large!
How do I get around this problem?

 

[electronrancher]

get the full version - you must be running the trial or student version limited to 25 or something transistors.

FYI - no i don't have the full version for you to download, plz don't even ask.


but... if you really want to build pwm, i can help.

Sawtooth wave + Error voltage => PWM

You could do that with 1 VPULSE source, 1 VDC, 1 op-amp, and 1 comparator. Op amp gets feedback signal (FB resistor divider) into inv input, and VDC (your reference voltage, try 1v) into noninv input. Oputput of opamp (Error amp) goes to inv input of comparator, and sawtooth wave (hopefully 0.5-1.5v for 1.0v Vref) goes to noninv input. Output of comparator is PWM.

Now for "bench" testing in spice.. Hook comparator to a 1k, hook 1k to .1uf to gnd. Connect output (between R and cap) back to feedback and the little monster will pwm until voltage on cap is equal to Vref.

Some examples are... 10v Vin, 1v Vref => 10% duty. 2v Vin, 1v Vref=> 50% duty.

 

[jgx]

see spice is very easy for simulate dc-dc converters

 

[alphi]

Pspice full version can do it,and you can easy get more example or model.
and saber is another better select for pwm dc-dc simulation.