SYSTEM FOR MEASURING EXCITATION CHARACTERISTICS OF MAGNETIC ASSEMBLIES USING DIRECT CURRENT

• US 20150094973A1
• Filed: 10/02/2013
• Published: 04/02/2015
• Est. Priority Date: 10/02/2013
• Status: Abandoned Application

• Current Assignee: Vanguard Instruments Company Inc. (ESCO Technologies, Inc.)
• Original Assignee: Vanguard Instruments Company Inc. (ESCO Technologies, Inc.)
• Inventors: Iwanusiw, Oleh, Glado, Iurii
• Application Number:
  US14/044,688
• Publication Number:
  US 20150094973A1
• Time in Patent Office: Days
• US Class Current: 702/65
• CPC Class Codes: G01R 33/14 Measuring or plotting hysteresis curves G01R33/1207 takes precedence

Abstract

A device and method to measure the excitation characteristics of magnetic assemblies using reversible direct current and converting direct current excitation data to alternating current excitation data at any power frequency.

Claims

1. A method to measure the excitation characteristics of magnetic assemblies using reversible direct current and converting direct current excitation data to alternating current excitation data at any power frequency, the method comprising the steps of:

a) repeatedly applying a low-level voltage range at power frequencies to a winding of a magnetic assembly;

b) measuring excitation current of the magnetic assembly;

c) determining the magnetic characteristics of the magnetic assembly under test; and

d) calculating one or more than one adjustment values to measure excitation characteristics of the magnetic assembly.

2. The method of claim 1, where the number of repetitions for applying the low-level voltage range at power frequencies is five to ten per decade, where each repetition represents a different excitation voltage and current that represent the excitation characteristics of the magnetic assembly when tested with at a fixed DC voltage and reversed at different time periods.

3. The method of claim 2, where results from the number of repetitions for applying the low-level voltage range at power frequencies are stored in a storage.

4. The method of claim 3, where results are retrieved from the storage and used in the calculation, where the calculation uses an integral of the voltage and the rms current to obtain an approximation of the magnetic characteristics of the magnetic assembly.

5. The method of claim 1, where a portion of the number of repetitions for applying the low-level voltage range at power frequencies are conducted using reverse polarity of the DC test voltage to provide a complete full cycle of excitation tests.

6. The method of claim 5, where the portion is between ten percent and no more than fifty percent.

7. The method of claim 1, where the calculation of the time integral of the applied voltage for each test point is proportional to the test voltage.

8. The method of claim 7, where the time integral of the applied voltage for each test point is converted to the average-reading voltage at the desired power frequency.

9. The method of claim 8, where the rms value of the current represents the excitation current for that test point.

10. The method of claim 7, where the test points are taken over a full range of excitation from a fully saturated condition to a fully unsaturated condition.

11. The method of claim 1, where the calculation uses equations 3, 3A and 4.

12. The method of claim 1, where low level voltage at the desired power frequency is applied to a winding of the magnetic assembly and the excitation current is measured and stored.

13. The method of claim 12, where the test is repeated over a range of voltages and used to calculate the adjustment.

14. The method of claim 13, where the measurements are retrieved and an intersection of the DC excitation and the power frequency excitation is determined.

15. The method of claim 1, further comprising adjusting the DC excitation characteristics to determine the full excitation characteristics of the magnetic assembly at the desired power frequency from a measurement using DC excitation.

16. The method of claim 1, where the calculation further comprises the steps of determining the adjustment and the equations for the DC excitation, the DC excitation characteristics and power frequency excitation.

17. The method of claim 1, further comprising the step of determining other parameters.

18. The method of claim 1, where the voltage and current for each point stored for the calculation is from a large number of measurements.

19. The method of claim 18, where each measurement comprises a DC voltage, a DC current and a time.

20. The method of claim 19, where the rms value of the current is calculated from the formula:

21. The method of claim 19, where an average value of the voltage is calculated from the formula:

22. The method of claim 18, where each point stored for the calculation has between 200 to 800 measurements of current and voltage.

23. The method of claim 1, where the raw data is corrected using the calculated adjustment.

24. The method of claim 23, further comprising a method to determine this correction, the steps of the correction comprising:

a) applying a sine wave voltage of the power frequency to a secondary winding of the magnetic assembly;

b) measuring a resulting excitation current (rms) at several selected voltages;

c) calculating a AC U/I characteristic using the formulas;

25. The method of claim 24, where the selected voltages comprise a range of 1-60 volts.

26. A device to measure the excitation characteristics of magnetic assemblies using reversible direct current and converting direct current excitation data to alternating current excitation data at any power frequency, the device comprising:

a) a main power module;

b) a voltage and current regulator electrically connected to the main power supply;

c) an H-bridge inverter electrically connected to the voltage and current regulator, a relay steering module and a transformer;

d) a relay steering module electrically connected to magnetic assembly;

e) a transformer electrically connected to one or more than one voltage and current measurement circuits;

f) the one or more than one voltage and current measurement circuits electrically connected to the H-bridge inverter; and

g) one or more than one microprocessors communicatively coupled to the voltage and current regulator, the H-bridge inverter and the one or more than one voltage and current measurement circuits.

27. The device of claim 26, where the main power module supplies the required voltage and current necessary to test a magnetic assembly,

28. The device of claim 26, where main power module can comprise batteries, 110V or 220V.

29. The device of claim 26, where the voltage and current regulator provides accurate and consistent voltages and currents to the H bridge inverter.

30. The device of claim 26, where the H bridge inverter comprises an electronic circuit that enables a voltage to be applied across a load in either direction, where the H bridge inverter provides the necessary reversal of DC voltage to conduct testing of the magnetic assembly. A relay steering circuit receives both DC pulse signals from the H bridge inverter and AC test signals from a transformer.

31. The device of claim 26, where the transformer receives input signals from the H bridge inverter to produce the correct AC test signals, where the input signals are from 50 Hz to 240 Hz AC.

32. The device of claim 26, where the relay steering circuit can transmit both the DC pulse signals and the AC test signals to the magnetic assembly being tested.

33. The device of claim 26, where the relay steering circuit receives and routes voltages and currents received from the magnetic assembly under test and can transmit the received voltages and currents to a voltage and current measurement module.

34. The device of claim 26, where the voltage and current measurement module comprises one or more than one measurement circuits.

35. The device of claim 26, where the one or more than one microprocessor controls all operation of the device and all of the testing for the magnetic assembly.

36. The device of claim 35, where the one or more than one microprocessor comprise instructions stored in a memory to control the testing parameters, receive inputs from the voltage and current measurement module and calculate an adjustment needed to complete tests compliant with the ANSI/IEEE C57.13.1 Standard.