I've been thinking about a couple of approaches to doing this.

The cognoscenti seem to go with stepping up the DC to a high voltage (165V for 120V/60Hz, or 330V for 230V), then using a high-voltage direct PWM to make the output without a transformer. And indeed you can find lots of literature and examples of that kind of topology; it's also what's used for motor drives too and some Class D amplifiers. The advantage is that the step-up can use a high frequency and thus lower inductance, saving cost, weight and size. The whole point of using newer devices like GaN and SiC IGBTs is to be able to deal with these high voltages directly. Your design could leverage the work in this area.

The second approach, which is kind of what you're doing, is to treat the AC signal as if it were a bridged Class D amplifier feeding a transformer. I think it's laudable that you're doing this, as it can enhance the safety of your inverter by allowing the secondary to float. The downside is that the final transformer needs to support very large primary currents, yet have large enough inductance to work at the low frequency required. This will make the converter more bulky overall: the primary windings need to be big to handle the current, as does the core for the needed inductance.

I think a middle path might be better. I like the idea of having isolation, but how to make the transformer more... reasonable? Here's the idea: step your 24VDC up to 72VDC (3x) using a flyback or other suitable topology. Then run a bridged Class D from that DC rail to make a ~164V differential swing. Then feed that to a 1:1 transformer to get the isolation. By dividing up the work, both the step-up and isolation transformer primary currents and voltages are a bit more manageable.

I've been thinking about a couple of approaches to doing this.

The cognoscenti seem to go with stepping up the DC to a high voltage (165V for 120V/60Hz, or 330V for 230V), then using a high-voltage direct PWM to make the output without a transformer. And indeed you can find lots of literature and examples of that kind of topology; it's also what's used for motor drives too and some Class D amplifiers. The advantage is that the step-up can use a high frequency and thus lower inductance, saving cost, weight and size. The whole point of using newer devices like GaN and SiC IGBTs is to be able to deal with these high voltages directly. Your design could leverage the work in this area.

The second approach, which is kind of what you're doing, is to treat the AC signal as if it were a bridged Class D amplifier feeding a transformer. I think it's laudable that you're doing this, as it can enhance the safety of your inverter by allowing the secondary to float. The downside is that the final transformer needs to support very large primary currents, yet have large enough inductance to work at the low frequency required. This will make the converter more bulky overall: the primary windings need to be big to handle the current, as does the core for the needed inductance.

I think a middle path might be better. I like the idea of having isolation, but how to make the transformer more... reasonable? Here's the idea: step your 24VDC up to 84VDC (3.5x) using a flyback or other suitable topology. Then run a bridged Class D from that DC rail to make a ~168V differential swing. Then feed that to a 1:1 transformer to get the isolation. By dividing up the work, both the step-up and isolation transformer primary currents and voltages are a bit more manageable.