Design of a mass‐production low‐cost claw‐pole motor for an automotive application

This paper describes a thermal and electrical model, used at Robert Bosch GmbH for the design of an innovative motor for a water‐pump. In addition, it offers an example of a highly integrated mechatronic system. A bonded‐ferrite inner rotor has been developed with an integrated front centrifugal impeller which is driven by the magnetic interaction of a rotating field created by claw‐poles. The two phase unipolar coil arrangement is fed by an internal circuit using two MOSFETS controlled by the commutation signal from a bipolar Hall‐IC. This is the first mass‐production example of an electrical machine for an automotive application where the claw pole topology is used to realise the armature of the motor (i.e. the rotating field) and not the excitation field.