How to design a 400Hz 12W inverter?

[ze_dib]

Hi guys,

I'm working on a 400Hz 26Vrms 12W inverter but I had a few difficulties..

The system is defined as : An oscillator with generate the 400Hz sinus wave. It become a reference signal for the output.

This signal is chopped vith a sawtooth signal to drive a H bridge. The load of the h bridge is the primary of the output transformer.

As I don't know the value of the self in the load, I can't use output wave for the feedback signal, because they will probably never be in phase.
I tried to use output enveloppe to make a close loop and assume a permament amplitude of the output signal, but I can't reach a good behavior

Here is a ltspice simulation of the circuit.

How can I do, without any software, to design the 400Hz 26VRms inverter

Please help.

regards,

 

[hman]

12w inverter

i recommend that you make the main sin wave with digital signals instead of oscillator to able to control in any phase of signal and then compare it to produce pwm signal such as other converters

 

[FvM]

inverter 400hz circuit

You're apparently assuming, that a closed loop output voltage control is neccessary with your inverter. I don't think, that this is that obvious. It may be the case, if tight voltage limits have to be kept.

A direct voltage feedback, including the output transformer in the loop, should be generally possible, if required. The transformer leak inductance must be kept low, which is meaningful for a good performance anyway and shouldn't be an issue at 400 Hz to my opinion.

The other way, a closed loop control of rectified output voltage, should also work, but basically requires a multiplier or another means to modulate either the sine or the pwm ramp voltage. And the controller should have a PI rather than only a P characteristic, as in your simulation circuit.