SELF-CALIBRATING LINEAR VOLTAGE DIFFERENTIAL TRANSFORMER DEMODULATOR

• US 20160320217A1
• Filed: 04/30/2015
• Published: 11/03/2016
• Est. Priority Date: 04/30/2015
• Status: Active Grant

• Current Assignee: Global Engineering Center - India (IDC), Goodrich Aerospace Services Private Limited (Rtx Corporation)
• Original Assignee: Goodrich Corporation (Rtx Corporation)
• Inventors: Ninjuri, Natraj, Rao, Kalluri, Ronning, Eric Duane
• Granted Patent: US 10,132,663 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01D 18/00 Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00
• CPC Class Codes: G01D 5/20 by varying inductance, e.g. by a movable armature
• CPC Class Codes: G01D 5/2291 Linear or rotary variable differential transformers (LVDTs/RVDTs) having a single primary coil and two secondary coils
• CPC Class Codes: G01R 33/0017 Means for compensating offset magnetic fields or the magnetic flux to be measured; Means for generating calibration magnetic fields
• CPC Class Codes: G01R 33/0035 Calibration of single magnetic sensors, e.g. integrated calibration
• CPC Class Codes: G05B 2219/37124 Magnetic sensor
• CPC Class Codes: G05B 2219/37185 Magnetic ring and sensor

Abstract

A calibration system includes an excitation module that introduces an excitation signal to a primary coil of a differential transformer, a measurement module that measures, at a first phase shift, a positive value of an induced signal. The induced signal is caused by the excitation signal on a secondary coil of the differential transformer. The system further includes a calculation module that compares the positive value to a last positive value to form a compared positive value, and a calibration module that changes the first phase shift based on the compared positive value.

Claims

1. A calibration system comprising:

an excitation module that introduces an excitation signal to a primary coil of a differential transformer;

a measurement module that measures, at a first phase shift, a positive value of an induced signal, the induced signal being created in a secondary coil of the differential transformer due to the excitation signal;

a calculation module that compares the positive value to a last positive value to form a compared positive value; and

a calibration module that changes the first phase shift based on the compared positive value.

2. The system of claim 1, wherein the first phase shift is increased if the positive value is less than the last positive value and is decreased if the positive value is greater than the last positive value and wherein, the calculation module determines a peak positive value.

3. The system of claim 2, wherein the measurement module measures, at a second phase shift, a negative value of the induced signal.

4. The system of claim 3, wherein the calculation module compares the negative value to a last negative value to form a compared negative value, wherein the calibration module changes the second phase shift based on the compared negative value.

5. The system of claim 4, wherein the calculation module determines a peak negative value.

6. The system of claim 5, wherein the calculation module determines a peak-to-peak value based on the peak positive value and the peak negative value.

7. A calibration method comprising:

introducing an excitation signal to a primary coil of a differential transformer;

measuring, at a first phase shift, a positive value of an induced signal, the induced signal being created in a secondary coil of the differential transformer due to the excitation signal;

comparing the positive value to a last positive value to form a compared positive value; and

changing the first phase shift based on the compared positive value.

8. The method of 7, wherein the first phase shift is increased if the positive value is less than the last positive value and is decreased if the positive value is greater than the last positive value.

9. The method of claim 8, further comprising determining a peak positive value.

10. The method of claim 9, further comprising measuring, at a second phase shift, a negative value of the induced signal.

11. The method of claim 10, further comprising comparing the negative value to a last negative value to form a compared negative value, wherein the calibration module changes the second phase shift based on the compared negative value.

12. The method of claim 11, further comprising determining a peak negative value.

13. The method of claim 12, further comprising a peak-to-peak value based on the peak positive value and the peak negative value.

14. The method of claim 11, further comprising generating shifted enable pulses based at least in part on the first phase shift.

15. The method of claim 11, further comprising generating shifted enable pulses based at least in part on the second phase shift.