System for detecting failures on a linear motor track

Patent metadata

Field	Value
Publication number	US-10585145-B2
Application number	US-201715703188-A
Country	US
Kind code	B2
Filing date	Sep 13, 2017
Priority date	Sep 13, 2017
Publication date	Mar 10, 2020
Grant date	Mar 10, 2020

Abstract

Sections of a linear motor track can each include a single power sensor configured to detect a power current in an erroneous state and one or more reference sensors configured to detect reference currents in erroneous states. The power sensor can be arranged between multiple drive coils of a section and a DC power rail (or “mid-bus”) for the drive coils. The power sensor can produce a single isolated output to a processor for the section, and the processor, in turn, can compare the output to a threshold for determining an error. The one or more reference sensors can be arranged between lower switches and a DC-reference bus, thereby providing a DC-referenced sensing signal for the drive coil currents. By referencing the processor to the same rail as the DC-referenced current sensing circuit, the reference sensors can produce outputs to the processor without any need for isolation.

First claim

What is claimed is:

1. A track segment for a linear motor drive system, the track segment comprising:
a first DC voltage rail configured to provide DC power;
a second DC voltage rail configured to provide half DC power;
a third DC voltage rail configured to provide a DC-reference;
a plurality of drive coils spaced along the track segment, the plurality of drive coils being coupled to the second DC voltage rail;
a plurality of first switches in communication with the plurality of drive coils, the plurality of first switches being coupled to the third DC voltage rail, wherein each switch of the plurality of first switches is configured to connect a drive coil of the plurality of drive coils to the third DC voltage rail in a first state or disconnect the drive coil of the plurality of drive coils from the third DC voltage rail in a second state;
a plurality of second switches in communication with the plurality of drive coils, the plurality of second switches being coupled to the first DC voltage rail, wherein each switch of the plurality of second switches is configured to connect a drive coil of the plurality of drive coils to the first DC voltage rail in the second state or disconnect the drive coil of the plurality of drive coils from the first DC voltage rail in the first state; and
a sensor arranged between the plurality of drive coils and the second DC voltage rail, the sensor being configured to produce an output corresponding to a current between the plurality of drive coils and the second DC voltage rail.

2. The track segment of claim 1 , further comprising a processor in communication with the sensor, the processor executing a program stored in a non-transient medium to compare the output to a predetermined current threshold and produce an alert when the output exceeds the predetermined current threshold.

3. The track segment of claim 2 , further comprising an isolation circuit arranged between the sensor and the processor, wherein the processor receives the output through isolation.

4. The track segment of claim 3 , wherein the isolation circuit is an optical isolation circuit.

5. The track segment of claim 1 , wherein the sensor is a DC power sensor, and further comprising a DC reference sensor arranged between a switch of the plurality of first switches and the third DC voltage rail, the DC reference sensor being configured to produce an output corresponding to a current between the switch of the first plurality of switches and the third DC voltage rail.

6. The track segment of claim 5 , further comprising a processor in communication with the DC power sensor and the DC reference sensor, the processor executing a program stored in a non-transient medium to compare the output of the DC power sensor to a first predetermined current threshold, compare the output of the DC reference sensor to a second predetermined current threshold and produce an alert when the output of the DC power sensor exceeds the first predetermined current threshold or the output of the DC reference sensor exceeds the second predetermined current threshold.

7. The track segment of claim 6 , further comprising an isolation circuit arranged between the DC power sensor and the processor, wherein the processor receives the output of the DC power sensor through isolation, and wherein the processor receives the output of the DC reference sensor without isolation.

8. The track segment of claim 7 , wherein the processor is coupled to the third DC voltage rail.

9. The track segment of claim 8 , wherein the third DC voltage rail is ground.

10. The track segment of claim 1 , wherein the switches are insulated-gate bipolar transistors.

11. The track segment of claim 1 , wherein the sensor is a resistor.

12. The track segment of claim 1 , wherein the sensor is a Hall effect current transducer.

13. A track segment for a linear motor drive system, the track segment comprising:
a first DC voltage rail configured to provide DC power;
a second DC voltage rail configured to provide half DC reference;
a third DC voltage rail configured to provide a DC-reference;
a plurality of drive coils spaced along the track segment, the plurality of drive coils being coupled to the second DC voltage rail;
a plurality of first switches in communication with the plurality of drive coils, the plurality of first switches being coupled to the third DC voltage rail, wherein each switch of the plurality of first switches is configured to connect a drive coil of the plurality of drive coils to the third DC voltage rail in a first state or disconnect the drive coil of the plurality of drive coils from the third DC voltage rail in a second state;
a plurality of second switches in communication with the plurality of drive coils, the plurality of second switches being coupled to the first DC voltage rail, wherein each switch of the plurality of second switches is configured to connect a drive coil of the plurality of drive coils to the first DC voltage rail in the second state or disconnect the drive coil of the plurality of drive coils from the first DC voltage rail in the first state;
a plurality of DC reference sensors arranged between the plurality of first switches and the third DC voltage rail, each DC reference sensor of the plurality of DC reference sensors being configured to produce an output corresponding to a current between a switch of the plurality of first switches and the third DC voltage rail; and
a DC power sensor arranged between the plurality of drive coils and the second DC voltage rail, the DC power sensor being configured to produce an output corresponding to a current between the plurality of drive coils and the second DC voltage rail.

14. The track segment of claim 13 , further comprising a processor in communication with the plurality of DC reference sensors, the processor executing a program stored in a non-transient medium to compare outputs of the plurality of DC reference sensors to a predetermined current threshold and produce an alert when an output exceeds the predetermined current threshold.

15. The track segment of claim 13 , wherein the processor is further in communication with the DC power sensor, the processor executing a program stored in a non-transient medium to compare the output of the DC power sensor to a second predetermined current threshold and produce an alert when the output of the DC power sensor exceeds the second predetermined current threshold.

16. The track segment of claim 15 , further comprising an isolation circuit arranged between the DC power sensor and the processor, wherein the processor receives the output of the DC power sensor through isolation, and wherein the processor receives outputs of the plurality of DC reference sensors without isolation.

17. The track segment of claim 16 , wherein the isolation circuit is an optical isolation circuit.

Assignees

• Rockwell Automation Tech Inc

Inventors

• Shirazi Omid
• Ganesan Nandini
• Ozimek Patrick E

Classifications

• G01R31/005

  Testing of electric installations on transport means · CPC title

• G01R21/08

  by using galvanomagnetic-effect devices, e.g. Hall-effect devices · CPC title

• G01R31/34 Primary

  Testing dynamo-electric machines · CPC title