DRV10983EVM: the phase to phase of BLDC motor

Part Number:DRV10983EVM

Now I want to measure the phase to phase voltage Ep of the motor.

So I use the oscilloscope voltage probe to directly measure the voltage between phase U and phase W.

But, the motor stop right away.

Are there problems with this measurement?

I don't know much about the motor.Can you recommend books of  the BLDC.