Comet-ME has developed a solar-powered submersible borehole ... of the SMPP is a three-phase tubular linear BLDC [brushless DC electric] motor, directly driving a plunger in a dual action mode ...

Doing so is a good way to understand their operation, and thus to design better brushless motor powered projects. Few of us will have gone as far as [etischer] though, and embarked upon building ...