ebm-papst

Abstract: The present invention pertains to a stator for an electric motor, composed of a stator core assembly (2), stator windings (3) and, arranged at one end of the stator core assembly (2), an interconnecting arrangement (4) for the stator windings (3). An interconnecting arrangement (4) features an insulating part (9) with slotted chambers (11) in order to accept electrical connecting leads (12), insulated from each other, in order to interconnect the wire ends (7) of the stator windings (3).

Abstract: In external rotor permanent magnet synchronous motors with non-overlapping windings, the higher frequency harmonics of the radial forces generate considerable resonant vibrations and acoustic noise. Therefore, diversity of spatial and specifically frequency harmonic ordinal numbers of representative slot and pole number combinations are derived analytically with open circuit and under load. Amplitudes of radial force waves are calculated by means of the finite element method and 2-D Fourier analysis. The obtained results confirm the analytical investigation. Determining factors on amplitudes are studied on machines having different slot and pole numbers and double-layer windings. Higher frequency harmonics significantly depend on the pole and tooth shape as well as the current profile. With open circuit, the calculations are validated by experiments. The findings are applied to reduce the noise of a centrifugal fan.

Abstract: A low-ripple multi-phase internal rotor motor has a slotted stator ( 28 ) separated by an air gap ( 39 ) from a central rotor ( 36 ). The rotor has a plurality of permanent magnets ( 214 ), preferably neodymium-boron, arranged in pockets ( 204 ) formed in a lamination stack ( 37 ), thereby defining a plurality of poles ( 206 ) separated by respective gaps ( 210 ). In a preferred embodiment, the motor is three-phase, with four rotor poles and six stator poles. As a result, when the first and third rotor poles are so aligned, with respect to their opposing stator poles, as to generate a reluctance torque, the second and fourth rotor poles are aligned to generate oppositely phased reluctance torques, so that these torques cancel each other, and essentially no net reluctance torque is exerted on the rotor. In order to magnetically separate the rotor magnets from each other, a hollow space ( 224, 238 ) is formed at the interpolar-gap-adjacent end face ( 216, 218 ) of each rotor magnet. A control circuit ( 147 ) provides electronic commutation and current control, based on rotor position signals generated with the aid of a control magnet ( 110 ) on the rotor shaft ( 40 ).

Abstract: The invention relates to a method for commutating an electronically commutated motor, by way of an improved commutation process that becomes effective between the cut-off of a voltage pulse and the switching on of a subsequent voltage pulse. On the basis of the current speed a cut-off time is calculated and once this cut-off time is reached, the power supply from a DC current source to the motor is disrupted. The winding to be switched off is operated in the short-circuit operation via two MOSFET transistors, and the declining current in the winding is monitored. Once the current has reached a reduced value, the winding connections of the winding are temporarily subjected to a high-ohmic voltage before the subsequent voltage pulse starts.

Abstract: An improved fan arrangement features a radial or diagonal fan ( 370 ) with which a direct current motor ( 32 ) is associated as its drive motor, further comprising a digital control element ( 23, 24 ) which executes a program, for controlling the current flowing through the direct current motor ( 32 ), which program is so configured that it applies a substantially constant current in the motor ( 32 ) in the working rotation speed range of the fan.