Most of the time when an orchid isn't blooming (and it is mature enough to bloom) is is due to lack of adequate light. Since you say your orchids are all growing well and that one is blooming but two are not, I am going to recommend that you give the two that are not blooming a 'cool down' period.
Some phals need to have a temp drop of at least ten degrees at night to initiate a spike. Once they spike, they can be grown in their normal location. If you were growing in a greenhouse, they might get that drop as part of a normal winter/ spring temp change. But, since you grow indoors, most people keep their homes around the same temp during the day and night, so our orchids that need that temp drop do not get it.
What can you do? Well, depending on where you live, if it is still cool outside (not below 40 degrees Fahrenheit) you could move your phals outside for a while. If it is possible they would get frost bite, then another trick some growers use is to move their indoor orchids next to a window at night and close a heavy curtain around them to keep the warmth of the room away from the orchid and the coolness of the outside near the orchid.
Whatever you decide to do, remember your phals cannot tolerate direct sun. Be sure to keep them or move them again before they get direct sun.
If it is not a cool down issue and is a light issue. (A photo of the leaves of the plant can help the members here offer their opinions on that) just increasing the light (causing a little stress to the very happily growing phal) will sometimes cause it to spike. If it is totally happy, it may not spike because it has no reason to reproduce.
Good luck to you.