Hi guys,

I'm making an inverter. To gen the PWM pulses to Mosfet drivers i'm using a TL494.

The IC is generating a internal sawtoth wave @40khz.
I'm using "Error Amplifier 1" as an Input(sine wave) with unitary gain. And don't using "Error Amplifier 2".
I grounded the Output Ctrl so there is no flip flop.
I hope that circuit makes an sawtoth(40khz) that samples sine wave(60hz). Then PWM comparator makes the pulses to Mosfet drivers.

I'm using orcad capture CIS, the circuit is atached.

I got that errors:

"ERROR -- Convergence problem in transient analysis at Time = 749.6E-06"
These supply currents failed to converge:
I(X_U1.xinsttl494.Ev103) = -29.80nA \ 0A
I(X_U1.xinsttl494.X_U3.X2.E1) = 219.09nA \ 218.83nA
I(X_U1.xinsttl494.X_U3.X2.E2) = 219.09nA \ 218.83nA
These devices failed to converge:
X_U1.xinsttl494.X_U3.X1.Q1

 

Should you be driving that chip with a sine wave which goes negative? Try adding a DC offset to keep the sine positive.

 

Thanks Alec_t for your reply.
I tried a 2v amplitude sine wave with 2v DC. It did not work...

 

Try taking pin 16 to ground instead of 2.5V.

 

Maybe this could help: