Several existing invention patents are combined into a product by a new combination method (different structures and the same principle). What kind of patents are they?

utility model, but the method and formula cannot be applied for utility model.

(A large-scale waste processor is made by using the above two principles: bacteria generate electricity to electrolyze refractory waste, and the products provide bacteria with nutrition while continuing to generate electricity). Have you applied for a patent for this thing? If not, you should be able to apply for invention.