Baldor Electric Company

Abb Schweiz Ag

Richard J Budzynski

Robert F McElveen, Jr

Michael J Melfi

Jukka T Jarvinen

A synchronous electrical motor, which may operate poly-phase electrical power, is configured to operate at a rated flux configuration and a high flux configuration. To enable the high flux configuration, some coils wound about the stator of the electric motor can be designated bypass coils and can be selectively disconnected from the power source supplying the motor with electrical power. The remaining permanent coils continue to receive full line power and generate a rotating magnetic field with an increased magnetic flux. At startup from standstill conditions, the bypass coils are selectively disconnected so that a flux boost occurs and a corresponding increase in output torque of the electric motor.

Electric motor with selective flux stator

A rotor for an LSIPM comprises a plurality of permanent magnets defining a number of poles ('P') of the LSIPM, and a plurality of rotor bars spaced about the rotor defining a rotor bar area ('BA'). The rotor bars are formed of a conductive material having an associated conductivity (&#x201c;&#x3c3;&#x201d;). End members are disposed on axial opposite ends of the rotor core. The end members are in electrical contact with the rotor bars. The end members are formed from a material having an associated conductivity (&#x201c;&#x3c3;&#x201d;). Each end ring member has a minimum geometric cross sectional area (&#x201c;ERA&#x201d;) and outer diameter that generally corresponds to the rotor core outer diameter. The ERA is greater than 0.5 times the rotor bar area per the number of poles (BA/P) times a ratio of the rotor bar material conductivity to the end member material conductivity (&#x3c3;/&#x3c3;).

End ring and rotor bar for line start permanent magnet motor

A method for synchronizing a high inertial load with a line-start synchronous motor involves providing a rotor core with rotor bars being formed of a highly conductive material. In accordance with one aspect of the method, a user is directed to operatively couple a load to the motor and drive the load from start to at least near synchronous speed during steady state operation of the motor with the load coupled thereto. The load has an inertia that is greater than an inertia associated with a load driven by a like motor subjected to an equivalent range of starting current but having rotor bars formed from a conductive material having a conductivity lower than that the highly conductive material.

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Simpsonville, SC, United States of America

Richard J Budzynski