Exodus 1-12

I do not understand why in an occasion, God means to harden Pharaoh’s heart as in chapter 7; verse 3: “And I will harden Pharaoh’s heart and multiply my signs and my wonders in the land of Egypt.” For why would God wish to harden Pharaoh’s heart, if he wanted most of all to free the children of Israel form Pharaoh? I suspect that he did this to starch out his hand, and smite Egypt with all his wonders and make Pharaoh suffer. But why would the Lord wish evil upon Pharaoh, if he is supposed to be holy and flawless and without ill wish for anyone?