Apparatus for avoiding harmful bearing currents

Patent metadata

Field	Value
Publication number	US-10284050-B2
Application number	US-201615737975-A
Country	US
Kind code	B2
Filing date	May 4, 2016
Priority date	Jul 24, 2015
Publication date	May 7, 2019
Grant date	May 7, 2019

Abstract

The present invention relates to an apparatus for reducing and/or avoiding harmful bearing currents in an electrical machine (M) such as preferably a three-phase EC motor (M), with a rotor ( 2 ) and a stator ( 3 ) which is constructed in an insulated manner, wherein at least one outer bearing ring ( 4 a ) and one inner bearing ring ( 4 b ) are provided between rotor ( 2 ) and stator ( 3 ), comprising connecting electronics ( 10 ) for connecting the motor (M), wherein the stator ( 3 ) is connected by means of an electrical connection ( 20 ) to a high-frequency electronics potential ( 11 ) which differs from the earth potential (U E ) and is stable with respect to the latter at a potential tap ( 20 a ) of the connecting electronics ( 10 ).

First claim

The invention claimed is:

1. An apparatus ( 1 ) for reducing and/or avoiding harmful bearing currents in an electrical machine (M) comprising a three-phase EC motor (M), with a rotor ( 2 ) and a stator ( 3 ) which is constructed in an insulated manner, wherein at least one outer bearing ring ( 4 a ) and one inner bearing ring ( 4 b ) are provided between rotor ( 2 ) and stator ( 3 ), comprising connecting electronics ( 10 ) for connecting the motor (M), wherein the stator ( 3 ) is connected by means of an electrical connection ( 20 ) to a high-frequency electronics potential ( 11 ) which differs from the earth potential (U E ) and is stable with respect to the latter at a potential tap ( 20 a ) of the connecting electronics ( 10 );
characterized in that the connecting electronics ( 10 ) comprises a rectifier ( 14 ), an intermediate circuit ( 15 ) and an inverter ( 16 ), and the potential tap ( 20 a ) in the connecting electronics ( 10 ) is provided so that the electronics potential ( 11 ) connected to the stator ( 3 ) corresponds to a potential of the intermediate circuit ( 15 ), to the positive intermediate circuit potential (DC+), to a ground potential of the intermediate circuit ( 15 ), to a potential at the center tap ( 15 ′) of the intermediate circuit ( 15 ) or to the negative intermediate circuit potential (DC−).

2. The apparatus ( 1 ) according to claim 1 , characterized in that the electrical connection ( 20 ) between the stator ( 3 ) and the electronics potential ( 11 ) is formed by an intermediate capacitance ( 21 ) or via an intermediate impedance.

3. The apparatus ( 1 ) according to claim 1 , characterized in that the electrical connection ( 20 ) between the stator ( 3 ) and the electronics potential (U E ) is formed as an electrical short circuit connection.

4. The apparatus ( 1 ) according to claim 1 , characterized in that the potential tap ( 20 a ) for the stator ( 3 ) is a tap immediately before or immediately after the rectifier ( 14 ).

5. The apparatus ( 1 ) according to claim 1 , characterized in that the connecting electronics ( 10 ) moreover comprises an EMC filter ( 17 ) on the input side, and the potential tap ( 20 a ) for the stator ( 3 ) is a tap within the EMC filter ( 17 ).

6. The apparatus ( 1 ) according to claim 1 , characterized in that the connecting electronics ( 10 ) is connected to a low-voltage power supply or switching power supply, and the potential tap ( 20 a ) for the stator ( 3 ) is provided as a tap at the outputs of the low-voltage power source or of the switching power supply.

7. The apparatus ( 1 ) according to claim 1 , characterized in that the rectifier ( 14 ) is an active or passive rectifier.

8. The apparatus ( 1 ) according to any one of claim 1 , characterized in that a network which reduces impedance in the frequency range of the bearing voltage is connected in parallel to at least one of diodes ( 14 a ) of the rectifier ( 14 ).

9. An electric motor (M), preferably an EC motor, designed with an apparatus ( 1 ) according to claim 1 .

Assignees

• Ebm Papst Mulfingen Gmbh & Co Kg

Inventors

• Schroth Sebastian
• Oberst Roland
• Pils Malte
• Weckert Marco

Classifications

• H02P27/06 Primary

  using DC to AC converters or inverters (H02P27/05 takes precedence) · CPC title

• H02K11/40

  Structural association with grounding devices · CPC title

• H02K11/20

  for measuring, monitoring, testing, protecting or switching (rectifiers H02K11/04; power electronics H02K11/33) · CPC title

• H02K5/1732 Primary

  radially supporting the rotary shaft at both ends of the rotor (H02K5/1737 takes precedence) · CPC title