All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
If the matter was just writing the word of divorce and the husband did not utter it, then writing the word of divorce is a metaphor of divorce and divorce does not take place with it unless it is accompanied with intention as we clarified in Fatwa 89894.
Therefore, if he intended divorce when writing it or that he wrote divorce while uttering it, then divorce took place three times according to the view of the majority of the scholars if he wrote the second and third words of divorce while intending to initiate divorce with each of them, but if he did not intend to initiate divorce with the second and third words of divorce, then it is only one divorce that took place.
If we presume that there is only one divorce that took place, then it is permissible for the husband to take back his wife without a new contract if she is still in her waiting period provided this divorce is not preceded by two divorces.
On the other hand, if we presume that three divorces had taken place, then his wife has become irrevocably divorced from him (with major separation) and it is not permissible for him to take her back unless she marries another man who really consummates the marriage with her and then he divorces her or dies as clarified in Fatwa 87878. For more benefit on the kinds of divorce, please refer to Fatwa 82541.
Finally, it should be noted that it is not a condition for divorce to take place that the wife knows about it, but whenever the divorce is issued by the husband, it takes place.
Allaah Knows best.