System and method for controlling a variable speed drive of a compressor motor

Patent metadata

Field	Value
Publication number	US-9759469-B2
Application number	US-201214238340-A
Country	US
Kind code	B2
Filing date	Aug 31, 2012
Priority date	Aug 31, 2011
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

A variable speed drive (VSD) can be used to vary the voltage-to-frequency ratio (V/f) supplied to a compressor motor of a heating, ventilation, air conditioning or refrigeration (HVAC&R) system to make the motor stronger or weaker to compensate for varying conditions in the HVAC&R system. The VSD and corresponding control system or algorithm can monitor an operating parameter of the HVAC&R system, such as the kW absorbed by the motor, and then raise or lower the V/f of the VSD to obtain the lowest possible power consumption from the motor.

First claim

The invention claimed is:

1. A system comprising:
a compressor, a condenser, an expansion device and an evaporator connected in a closed refrigerant circuit;
a motor connected to the compressor to power the compressor;
a variable speed drive connected to the motor to power the motor, the variable speed drive being operable to provide a variable voltage to the motor and a variable frequency to the motor;
a control panel to control operation of the variable speed drive and one or more components of the system;
a sensor to measure an operational parameter of the system, the sensor being operable to communicate the measured operational parameter to the control panel; and
the control panel being operable to execute a control algorithm to adjust a voltage-to-frequency ratio to be output by the variable speed drive based at least on the measured operational parameter, wherein the determined voltage-to-frequency ratio optimizes sound attenuation of the compressor, and wherein the voltage-to-frequency ratio is between 1.5 Volts/Hertz and 2.0 Voltz/Hertz.

2. The system of claim 1 wherein the sensor measures power consumption of the motor.

3. The system of claim 1 wherein the sensor measures a discharge temperature of the compressor.

4. The system of claim 1 wherein the sensor measures a temperature of the motor.

5. The system of claim 1 wherein the control algorithm includes a table of voltage-to-frequency ratios and corresponding operational parameter values.

6. The system of claim 1 wherein the control algorithm includes a fuzzy logic algorithm to determine the voltage-to-frequency ratio.

7. A method for controlling a variable speed drive, the method comprising:
measuring an operational parameter of an HV AC&R system;
determining a voltage-to-frequency ratio to be output by a variable speed drive using the measured operational parameter, the variable speed drive powering a compressor motor of the HV AC&R system;
generating control instructions for the variable speed drive based on the determined voltage-to-frequency ratio;
adjusting the output voltage-to-frequency ratio provided by the variable speed drive to the compressor motor with the generated control instructions, wherein the output voltage-to-frequency ratio is between 1.5 Volts/Hertz and 2.0 Voltz/Hertz; and
optimizing sound attenuation of a compressor driven by the compressor motor with the determined voltage-to-frequency ratio.

8. The method of claim 7 wherein said measuring an operational parameter includes measuring power consumption of the compressor motor.

9. The method of claim 7 wherein said measuring an operational parameter includes measuring a discharge temperature of a compressor.

10. The method of claim 7 wherein said measuring an operational parameter includes measuring a temperature of the compressor motor.

11. The method of claim 7 wherein said determining a voltage-to-frequency ratio includes selecting a voltage to frequency ratio from a table of voltage-to-frequency ratios and corresponding operational parameter values.

12. The method of claim 11 further comprising operating the HVAC&R system at varying conditions and voltage to frequency ratios to populate the table.

13. The method of claim 7 wherein said determining a voltage-to-frequency ratio includes executing a fuzzy logic algorithm to determine the voltage-to-frequency ratio.

14. The method of claim 7 further comprising optimizing compressor efficiency with the determined voltage-to-frequency ratio and the optimized sound attenuation.

Assignees

• Nemit Jr Paul
• Johnson Controls Tech Co

Inventors

• Nemit Jr Paul

Classifications

• F25B49/022 Primary

  Compressor control arrangements · CPC title

• F04B2203/0204

  Frequency of the electric current · CPC title

• F04C29/0085

  Prime movers · CPC title

• F25B2600/021

  Inverters therefor · CPC title

• F24F2011/0083

  Mechanical Engineering · mapped topic