About signal conversion
I can give a suggestion. May not work out. It goes something like this, if you don't want to get into complicated complex solution such as AC(50)-DC-AC(100)-DC-AC(150). Please comment if solution seems to be in lines of what you have been implementing.


A: 50 Hz signal
After passing A signal through a switched converter working to produce something like in Fig. B(Switching at 90 degree to alternate the waveform), you get a 100Hz signal. Now this signal contains many harmonics as n*100Hz.
To get the required 100Hz signal, you can pass it through the LPF Filter with cut-off frequency of 100Hz. Getting required 100 Hz signal.

Note: There are many things that needs to be pointed out in this simple looking solution such as:

Desired Output 230V may not be the output as there would be attenuation in the circuit

Proper 100Hz sine wave may not be there. Since LPF filter are not exactly cut-off at frequency. They have some roll-off rate.

Converter might be required to go from A-&gt;B. Might complicate the solution

Solution seems to be similar to cyclo-converter

Filter used may be bulky if used for high-power.