It will depend on the resolution (and frequency) of your PWM generator.
Unfortunately I do not know what will you use for generating it, so it will be a bit difficult to help you.
I suggest you to start to search for a microcontroller which permits you to generate the "typical" signals for a triphase sinewave (to drive an inductive motor): almost any new 16/32 bit microcontroller will be good.
If you are able enough, you can use also an 8 bit micro, but I really do not know your expertise and if your project is price constrained.
The filters (L/C) set to the output of the inverter will filter out the high frequency component of the PWM.
I can assure you that if you have the right experience it is not so difficult to reach very low levels of distortion.
The problem is that the developement of an inverter is not so easy if you want to satisfy all of the (security/EMC/...) norms like: EN 62040, EN 60950, EN 50091 and the other ones which at this moment I do not recall.
I also think a single person will take several months of full time developement to create a perfectly working prototype which can be sent to the production line.
Almost any of the "free" projects I have seen on the web (on edaboard too) do not take care at all about the safety rules in their projects: please remember that we are talking about hundreds of A and working with those kind of energies can be really dangerous (do not forget to always wear safety goggles!).