All he's done is divided the motor up into several three phase BLDC motors and used a controller for each. In his case he's used a 21 winding configuration and 7 controllers, but the idea should work with any multiple slot BLDC winding pattern I think.
If you had, for example, a common 12 slot stator, then you could wind it as four separate three phase windings, either in star or delta, and use a separate controller for each. You would need to bring all the separate winding wires out to connect them to the controllers, but it would work OK. Each controller would be driving its set of windings independently of the others. One problem to overcome is that the controllers would each be driving low inductance, low resistance, windings, so would need a high peak current capability.
Please ask questions on the forum, rather than by PM, as it helps others and you'll get a better range of answers.