U.S. Philips Corporation

Johannes H Janssen

Henricus M Van Hout

Jan Janson

Robertus I Van Steen

An electrical multipole machine comprises a first machine section (1), a second machine section (3) and a machine shaft (5), about which one machine section is rotatable relative to the other machine section. The first machine section comprises an annular permanent-magnet body (11) having a plurality of adjacent pole pairs (N; S). The second machine section comprises a lamination assembly (25) having teeth (27-35) and coils (37-45). The teeth comprise tooth surfaces (47-55) which are geometrically spaced from one another by slots (57-65) and from the magnet body by an air gap (67). Near the air gap the slots extend in a tangential direction over at least 80 electrical degrees and at the most 90 electrical degrees, or over at least 130 electrical degrees and at the most 150 electrical degrees. The ratio between the number of poles and the number of teeth is either 4:3 or 2:3.

Three-phase electrical machine with reduced cogging torque

A brushless d.c. motor comprises a commutation device by means of which the stator coils are connected to and disconnected from a direct-voltage source in a cyclic switching pattern for energizing said stator coils. In order to reduce torque variations as a result of transient effects in the energizing currents during commutation, the commutation device comprises means which cause the instants of disconnection and connection to be shifted by a fixed time interval relative to one another.

Brushless d.c. motor

An electric machine with electronic commutation includes two Hall elements arranged at an angular spacing about the rotor axis smaller than the phase difference .phi. required between the energizing signals in order to obtain a correct energization of the motor. The energizing circuit for the stator coils is provided with a combining circuit for linearly combining the signals obtained from the Hall elements in order to obtain signals with a phase difference equal to .phi..

Electronically commutating motor

A semiconductor device having a Hall element in which, in order to reduce the offset, the Hall element consists of an even number of sub-Hall elements provided in one semiconductor body and the anode and cathode contacts of which are connected together, which sub-Hall elements each have a Hall contact, and in which one half of the Hall contacts is of one polarity and the other half is of the opposite polarity. The sub-Hall elements are divided into groups of each two sub-Hall elements with mutually parallel main current directions, and Hall contacts of the same polarity are connected together. The sub-Hall elements advantageously have a common Hall body in the form of a square of another regular polygon, in which the contacts are placed along the edge of the Hall body.

Multisegment Hall element for offset voltage compensation

The invention relates to a collectorless d.c. machine which is provided with a disc which rotates with the rotor, in which disc magnetically coded tracks are provided which co-operate with magneto-sensitive elements for selectively energizing the stator coils depending on the rotor position. The invention in particular relates to a three-phase motor, while on a disc on the rotor shaft two magnetic codes are provided which are shifted through 120.degree. relative to each other. The magnetic codes are separately detected by a magneto-sensitive element. The two elements together with the associated electronic circuitry which amplifies the two signals and produces a third signal which has a 120.degree. phase shift relative to the two other signals, take the form of one integrated circuit. The invention relates to an electric machine comprising an electronic commutator and a rotor which at least partly consists of a magnetic material and co-operates with stationary stator coils. This machine is provided with a number of magneto-sensitive elements, in particular Hall elements, for selectively applying electric current to the stator coils depending on the rotor position.

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Eindhoven, Netherlands

Johannes H Janssen