Importance

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Abstract

High torque brushless motors are proposed which have low weight and high efficiency. The permanent magnet rotor has many equally spaced poles of alternating polarity. The stator has a plurality of pole groups, each pole group have a plurality of poles with the same pitch as the rotor poles. Windings (211-216, 221-226, 231-236, 241-246, 251-256, 261-266) connected to electrical phases (R, S, T) are provided on the poles within each pole group to polarize the poles in the group with alternating polarity. The pole groups are displaced relative to each other and the gaps between the pole groups are filled by flux balancing poles (217, 227, 237, 247, 257, 267) which in many cases are unwound. The motor may be driven by means of an inverter and by providing it with at least two winding sections of each phase, configuration switches to connect the winding sections in at least one serial and one quasi-parallel configuration and at least twice as many bridgelegs (twice as many inverter switching elements) as would otherwise be required as a minimum in the selected bridge configuration it can be driven at two different torques. The configuration switches may be constructed as very low resistance high current mercury switches having a favorable geometric design.

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First Claim