Well, I would read the following links:
Info about general BL DC motors:
Brushless DC Motors
Info about some of the math (but not necessarily about BL motors):
Three Phase Info
AFAIK, the LMT motors are all rated by the Delta configurations.
Simplified: If you look at the Delta part of the attached pic, you'll see that when voltage is applied to nodes Z and X, current will flow through Ra. In the Y config, you see that applying voltage to the Z and X nodes requires current to pass through R3
and R1
in series. So, current will be less. Also, the series coils increases the turns, so kv will be less as well.
However, it's not quite that simple. The fact that there is AC going through each coil 120* out of phase with each other produces some current vectors. It's not like you have voltage on one node and ground on the other two nodes, so it gets a little confusing.
Incidentally, in three-phase industrial electrical AC applications, the Y pic could be a 3-phase transformer with the outer nodes being the power outputs while the center node would be the neutral connection.