The bids were higher than the $11 billion to $13 billion range previously expected.
All three companies declined to comment, the report said. The bids were submitted this past weekend.
Blackstone and TRW have vowed not to close any German factories to sweeten its offer for the automotive electronics unit VDO, media reported over the weekend.
Siemens’s supervisory board is expected to hold a meeting on Wednesday at which it will discuss whether to sell VDO to Continental or TRW rather than floating the unit in an initial public offering.