I was planing to come September 22nd - october 2nd. Is this a good time or is it in a risk for typhoons?

Well, Typhoon seldom happens in Shanghai as the way it happens in the cities around the seaside. It won't bring much damage, but it may bring a lot of rain during September in Shanghai. Anyway, it is not in a risk for your travelling period. The weather is generally mild during that time in Shanghai with an average temperature around 20C. You'd better take an umbrella when go outside in Shanghai.