Method and device for determining the real power of a DC electrical drive

• US 5,614,817 A
• Filed: 06/23/1995
• Issued: 03/25/1997
• Est. Priority Date: 12/23/1992
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Kutzer, Heinz
• Primary Examiner(s): Wieder, Kenneth A.
• Assistant Examiner(s): BOWSER, BARRY
• Application Number:
  US08/494,052
• Time in Patent Office: 641 Days
• Field of Search: 324/142, 324/772, 318/798, 318/729, 318/812
• US Class Current: 324/142
• CPC Class Codes: G01R 31/34 Testing dynamo-electric machines

Abstract

A method for determining the real power of an electrical drive, preferably an electrical fitting drive, includes subtracting an ohmic or resistive power loss in a stator of the drive from a measured real power. It is intended that an ohmic or resistive power loss in a connecting line of the drive also be subtracted. A device for determining the real power of an electrical drive includes line pairs each connecting two connecting lines remotely from the drive, to a DC voltage source. A known ohmic or non-reactive resistor is inserted into one of the lines in each case. Each of the lines is connected on the side of the ohmic or non-reactive resistor facing toward the drive, through a voltmeter, to the other line. The voltmeters are connected to an evaluation unit.

Claims

1. A method for determining the real power of an electrical drive having a stator and a DC voltage connecting line producing ohmic power losses, which comprises:

subtracting the ohmic power loss produced in the stator of the drive from a measured real power; and

additionally subtracting the ohmic power loss produced in the DC voltage connecting line of the drive from the measured real power.

2. The method according to claim 1, which comprises not taking power losses produced in a rotor of the drive into account.

3. The method according to claim 1, which comprises not taking inductive power losses into account.

4. A method for determining the real power of an electrical fitting drive having a stator and a DC voltage connecting line producing ohmic power losses, which comprises:

subtracting the ohmic power loss produced in the stator of the drive from a measured real power; and

additionally subtracting the ohmic power loss produced in the DC voltage connecting line of the drive from the measured real power.

5. A device for determining the real power of an electrical drive, comprising:

connecting lines for stator windings of a drive, said connecting lines having connecting points remote from the drive;

a DC voltage source;

line pairs each having one line and another line, each of said line pairs connecting said connecting points of two of said connecting lines to said DC voltage source;

known ohmic resistors each being connected into said one line of a respective one of said line pairs;

voltmeters each being connected to said one line at a location between said ohmic resistor and said connecting point and each being connected to said other line of a respective line pair; and

an evaluation unit connected to said voltmeters.

6. The device according to claim 5, wherein said lines have taps, said voltmeters are a component of said evaluation unit, and said evaluation unit is connected to said taps for voltage measurement.

7. A device for determining the real power of an electrical fitting drive, comprising:

connecting lines for stator windings of a drive, said connecting lines having connecting points remote from the drive;

a DC voltage source;

line pairs each having one line and another line, each of said line pairs connecting said connecting points of two of said connecting lines to said DC voltage source;

known ohmic resistors each being connected into said one line of a respective one of said line pairs;

voltmeters each being connected to said one line at a location between said ohmic resistor and said connecting point and each being connected to said other line of a respective line pair; and

an evaluation unit connected to said voltmeters.

8. The device according to claim 7, wherein said lines have taps, said voltmeters are a component of said evaluation unit, and said evaluation unit is connected to said taps for voltage measurement.