Youngsters Flynn Downes, Conor McKendry and Luke Woolfenden have signed their first professional deals with the Blues.
The terms are understood to be one-year contracts with options for a further season, the trio having completed their two-year academy scholarships at the end of 2016/17.
Brentwood-born midfielder Downes, 18, (above) was on the bench for the final first team game of last season at Nottingham Forest having impressed manager Mick McCarthy in the latter stages of the campaign with his performances in the U23s.
"All-round, technically he’s a really good footballer," McCarthy said. "He’s athletic, he puts his foot in, he’ll compete, he’s a real competitor and he’s a winner on the pitch.
"He comes over and he shows no respect for the first team, he comes and dumps them on their backsides if they need dumping on their backsides. I love that about him."
Northern Ireland U16 and U17 international McKendry (above), also 18, is a winger, while Ipswich-born defender Woolfenden, again 18, plays at both centre-half and right-back.