Leeds United’s home defeat against Wolves meant Wednesday’s fourth win in a row moved the Owls up to fifth in the Championship with three matches left to play.
Last season’s beaten play-off finalists were made to battle at Loftus Road, where Daniel Pudil headed them back in front after Idrissa Sylla’s goal had cancelled out Adam Reach’s early opener.
“We are very strong mentally – the mentality of this team is very strong,” Carvalhal declared.
“When you play twice in three days, physical teams can cause you problems and it’s not easy to play twice in such a short time.
“But we are very strong and the confidence is high. We have four wins in a row and the mentality is really strong, which is why we achieved the three points.
“We knew before this game that it was one of the more difficult ones for us. I thought we were fantastic.
“We have been stronger since the international break and we are showing that we are strong. I am very happy with our players.
“We are ready for this part of the season. It will be three finals and our focus is on this.
“This is a marathon and let’s see where our position will be in the marathon.”
Rangers, meanwhile, have lost five matches in a row and sit just six points above the relegation zone with three games left.
QPR manager Ian Holloway said: “If we can get three in the next game at Brentford then everybody can just breathe and we can start again.”
Wednesday dominated most of the first half and went ahead in the 12th minute.
Pudil’s left-wing cross ricocheted into the path of Reach, who blasted in from near the edge of the six-yard box.
Sylla equalised from a similar position nine minutes later.
After Jamie Mackie exchanged passes with Ryan Manning and went down in the box, the loose ball rolled to Sylla, who fired past goalkeeper Keiren Westwood at the near post.
But the Owls hit back just after the half-hour mark, when Pudil followed up to head home after goalkeeper Alex Smithies had managed to keep out Jordan Rhodes’s header from Ross Wallace’s right-wing free-kick.
Wallace might have made it 3-1 had Jack Robinson not thwarted him with a last-ditch challenge.
QPR: Smithies, Perch, Lynch, Bidwell, Petrasso (LuaLua 46), Freeman, Luongo, Manning (Smith 75), Robinson (Washington 62), Mackie, Sylla. Unused substitutes: Goss, Ingram, Wszolek, Ngbakoto.
Sheffield Wednesday: Westwood, Palmer, Lees, Loovens, Pudil, Wallace (Semedo 67), Jones, Bannan, Reach, Rhodes (Nuhiu 76), Hooper (Forestieri 67). Unused substitutes: Wildsmith, Fletcher, McManaman, Sasso.
Referee: Andy Davies (Hampshire).