Method for selecting a frequency converter for a refrigerant compressor unit

Patent metadata

Field	Value
Publication number	US-11736053-B2
Application number	US-202016857746-A
Country	US
Kind code	B2
Filing date	Apr 24, 2020
Priority date	Oct 27, 2017
Publication date	Aug 22, 2023
Grant date	Aug 22, 2023

Abstract

In order to improve a method for selecting a frequency converter for a refrigerant compressor unit comprising a refrigerant compressor and an electric drive motor in such a way that the frequency converter is optimised for the application in question, it is proposed that a working state suitable for the operation of the refrigerant compressor unit is selected in an application field of an application diagram of the refrigerant compressor, that an operating frequency is selected for this selected working state, and that, on the basis of drive data, a working state operating current value corresponding to the selected working state and the selected operating frequency is ascertained for the operation of the refrigerant compressor unit.

First claim

The invention claimed is:

1. A method for selecting a frequency converter for a refrigerant compressor unit having a refrigerant compressor and an electric drive motor, the method comprising the steps of:
using an application diagram showing a saturation temperature at an inlet and a saturation temperature at an outlet of the refrigerant compressor and showing all permissible value pairs of the saturation temperature at the inlet and the saturation temperature at the outlet of the refrigerant compressor arranged in an application field enclosed on all sides by an application limit;
selecting a working state suitable for the operation of the refrigerant compressor within the application field of the application diagram of the refrigerant compressor;
selecting an operating frequency for this selected working state; and
using the selected working state and the selected operating frequency to extract experimentally-determined drive data for said refrigerant compressor unit, stored for each working state in said application field and the selected operating frequency of the refrigerant compressor unit, to determine, on the basis of the stored experimentally-determined drive data, a working state operating current value corresponding to the selected working state and the selected operating frequency for the operation of the refrigerant compressor unit.

2. A method for selecting a frequency converter for a refrigerant compressor unit having a refrigerant compressor and an electric drive motor, the method comprising the steps of:
using an application diagram showing a saturation temperature at an inlet and a saturation temperature at an outlet of the refrigerant compressor and showing all permissible value pairs of the saturation temperature at the inlet and the saturation temperature at the outlet of the refrigerant compressor arranged in an application field enclosed on all sides by an application limit;
selecting a working state suitable for the operation of the refrigerant compressor within the application field of the application diagram of the refrigerant compressor;
selecting an operating frequency for this selected working state; and
using the selected working state to extract experimentally-determined drive data for said refrigerant compressor unit, stored for each working state in said application field and using the selected operating frequency of the refrigerant compressor unit, to determine, on the basis of the stored experimentally-determined drive data, a working state operating current value corresponding to the selected working state and the selected operating frequency for the operation of the refrigerant compressor unit.

3. The method in accordance with claim 2 , wherein, on the basis of the working state operating current value, the frequency converter of which the maximum converter current value is equal to or greater than the ascertained working state operating current value is selected from data for those frequency converters that are available for selection.

4. The method in accordance with claim 3 , wherein the frequency converter of which the maximum converter current value is closest to the working state operating current value is selected.

5. The method in accordance with claim 2 , wherein the frequency converter is selected such that its maximum converter start-up current value is equal to or greater than a start-up current value of the refrigerant compressor unit.

6. The method in accordance with claim 5 , wherein a stored start-up current value is consulted for the selection of the frequency converter.

7. The method in accordance with claim 5 , wherein the start-up current value is determined experimentally.

8. The method in accordance with claim 5 , wherein the frequency converter is selected such that its maximum converter start-up current value is closer to the start-up current value than that of any other frequency converter.

9. The method in accordance with claim 5 , wherein the frequency converter is selected such that its maximum converter current value is closer to the higher of the values of the working state operating current and start-up current than that of any other frequency converter.

10. The method in accordance with claim 2 , wherein the operating frequency to be selected lies in the range of from 0 hertz to 140 hertz.

11. The method in accordance with claim 2 , wherein the drive data comprise the experimentally determined power consumption for each working state in the application field at the various operating frequencies.

12. The method in accordance with claim 11 , wherein the working state operating current value at the selected operating frequency is calculated on the basis of the experimentally ascertained electrical power consumption at the particular operating frequency taking into consideration an equivalent circuit of the drive motor of the refrigerant compressor unit.

13. The method in accordance with claim 2 , wherein impedance of an equivalent circuit impedance of the equivalent circuit of the drive motor is taken into consideration in order to ascertain the working state operating current value.

14. The method in accordance with claim 13 , wherein, in order to ascertain the working state operating current value, the experimentally ascertained electrical power consumption of the refrigerant compressor unit is compared with the power consumption resulting from the equivalent circuit and on this basis the slip or load angle is ascertained.

15. The method in accordance with claim 13 , wherein the working state operating current value is ascertained on the basis of the ascertained slip or load angle and the impedance of the equivalent circuit of the drive motor.

16. The method in accordance with claim 2 , wherein the working state operating current value is minimized by varying the output voltage of the frequency converter.

17. The method in accordance with claim 2 , wherein the experimentally determined electrical power consumption of each working state in the application field at the particular operating frequency is captured, in particular stored.

18. The method in accordance with claim 2 , wherein the working state operating current values calculated from the experimentally ascertained electrical power consumption are captured, in particular stored, for each working state and for each operating frequency.

19. The method in accordance with claim 2 , wherein the working state operating current value is experimentally ascertained and captured, in particular stored, for each working state and each operating frequency.

20. The method in accordance with claim 2 , wherein, on the basis of the maximum converter current value of the selected frequency converter, the working states belonging to this maximum converter current value are ascertained in the application field at a selected operating frequency with the aid of the drive data.

21. The method in accordance with claim 20 , wherein the working states ascertained in respect of the maximum converter current value are displayed visually in the application diagram.

22. The method in accordance with claim 2 , wherein there are selected only frequency converters that comprise a frequency-limiting unit, which, at operating frequencies above a cut-off frequency, limits the operating frequency in such a way that the maximum converter current value of the frequency converter is not exceeded.

23. The method in accordance with claim 22 , wherein the working state operating curre

Assignees

• Bitzer Kuehlmaschinenbau Gmbh

Inventors

• Gibson John
• Hieble Tobias
• Pfaffl Julian
• Nill Juergen
• Breithuth Ferdinand

Classifications

• H02P27/047 Primary

  V/F converter, wherein the voltage is controlled proportionally with the frequency · CPC title

• H02P23/00

  Arrangements or methods for the control of AC motors characterised by a control method other than vector control · CPC title

• F25B2500/26

  characterised by the startup of the refrigeration cycle · CPC title

• F25B2600/021

  Inverters therefor · CPC title

• H02P29/032

  Preventing damage to the motor, e.g. setting individual current limits for different drive conditions · CPC title