# US 7,608,950 B2 · Traction motor shaft connected to vehicle ground via drive gear

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- Number: US 7,608,950 B2
- Document ID: US7608950B2
- Status: Granted
- Kind: B2
- Application number: 10/550,125
- Filed: 2004-03-05
- Published: 2006-06-15
- Granted: 2009-10-27
- Earliest claimed: 2003-03-19
- Assignees: Siemens Aktiengesellschaft
- Inventors: Michael Brauer
- Web page: https://patentgrep.com/patent/US7608950B2

## CPC

- H02K 11/40: Structural association with grounding devices
- H02K 11/33: Drive circuits, e.g. power electronics (H02K11/38 takes precedence)
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})

## Abstract

In order to prevent bearing currents, particularly in converter-operated traction motors (1), the housing (11) is grounded via a grounding capacitor (Cground).

## Claims

### Claim 1

A traction drive system in a vehicle with an electric or diesel-electric drive, said vehicle representing a system ground potential, the drive system comprising:
a housing capacitively coupled to ground potential;
a traction motor received in the housing, said traction motor comprising a rotor shaft connected to ground potential via a drive gear and capacitively coupled to the housing, and a stator capacitively coupled to the housing and to ground potential; and
at least one grounding capacitor connected between the housing and ground potential.

### Claim 2 (depends on 1)

The traction drive system of claim 1, further comprising an electronic power actuating element for supply of power to the traction motor.

### Claim 3 (depends on 1)

The traction drive system of claim 1, further comprising a rotational speed sensor for realizing a grounding connection between the housing and a vehicle ground.

### Claim 4 (depends on 1)

The traction drive system of claim 1, further comprising a power cable for supply of power, and a shielding on the power cable for realizing a grounding connection between the housing and a vehicle ground.

### Claim 5 (depends on 1)

The traction drive system claim 1, further comprising a converter for realizing a grounding connection between the housing and a vehicle ground.

### Claim 6 (depends on 5)

The traction drive system of claim 5, further comprising a power cable for supply of power, wherein the grounding connection is realized via a separate line in the power supply cable.

### Claim 7 (depends on 1)

The traction drive system claim 1, further comprising a motor shaft operated by the traction motor, and a bearing for support of the motor shaft, wherein the grounding capacitor monitors an electrical voltage across the bearing to generate a measured variable of an operative grounding connection.

### Claim 8 (depends on 5)

The traction drive system of claim 5, further comprising a power cable for supply of power, and a shielding on the power cable, wherein the grounding connection is realized via the shielding of the power cable.