Motor housing temperature control system

Patent metadata

Field	Value
Publication number	US-9574805-B2
Application number	US-201415026547-A
Country	US
Kind code	B2
Filing date	Sep 24, 2014
Priority date	Oct 9, 2013
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

Abstract

A method and apparatus for controlling temperature of a compressor motor ( 170 ) having a motor cooling circuit in a refrigeration system ( 1014 ) is provided. The motor cooling circuit includes a second expansion valve ( 1043 ) providing fluid communication between the condenser and the compressor motor. The compressor motor ( 170 ) is in fluid communication with the refrigeration circuit ( 1014 ) between downstream of the first expansion valve ( 1040 ) and a compressor inlet. Refrigerant is provided as a cooling fluid to the motor cooling circuit. A primary PID loop ( 402 ) and a secondary PID loop ( 414 ) are used to control the temperature and the flow of refrigerant to the motor ( 170 ).

First claim

What is claimed is:

1. A method for controlling temperature of a compressor motor ( 170 ) having a motor cooling circuit, the compressor motor ( 170 ) in a refrigeration circuit ( 1014 ) comprising a compressor ( 1020 ) having a motor ( 170 ), a condenser ( 1030 ) in fluid communication with the compressor ( 1020 ), a first expansion valve ( 1040 ) in fluid communication with the condenser ( 1030 ), an evaporator ( 1050 ) in fluid communication with the first expansion valve ( 1040 ) and in fluid communication with the compressor ( 1020 ), the motor cooling circuit comprising a second expansion valve ( 1043 ) in fluid communication with the condenser ( 1030 ) and the compressor motor ( 170 ), the compressor motor ( 170 ) further being in fluid communication with the refrigeration circuit ( 1014 ) between downstream of the first expansion valve ( 1040 ) and a compressor inlet, wherein the compressor motor ( 170 ) further includes a stator ( 176 ) having windings and a rotor ( 178 ) mounted within a motor housing ( 174 ) and refrigerant fluid provided from the condenser ( 1030 ) to the motor cooling circuit as a cooling fluid through the second expansion valve ( 1043 ), wherein the improvement is characterized by:
providing a primary PID loop ( 402 ), the primary PID loop ( 402 ) including a compressor motor housing temperature sensor mounted on a motor housing surface, and a first PID controller ( 404 ) in communication with the motor housing temperature sensor, the first PID controller ( 404 ) further programmed with a motor housing temperature set point;
providing a secondary PID loop ( 412 ), the secondary PID loop ( 412 ) including a stator winding temperature sensor mounted on the stator windings and a second PID controller ( 414 ) in communication with the second expansion valve ( 1043 ) and the first PID controller ( 404 ), the second PID controller ( 414 ) further programmed with a stator winding temperature set point;
providing a signal indicative of the stator winding temperature to the second PID controller ( 414 );
providing a signal indicative of the motor housing temperature to the first PID controller ( 404 );
providing a signal from the second PID controller ( 414 ) to the second expansion valve ( 1043 ) regulating refrigerant flow to the motor cooling circuit when the stator winding temperature varies from the stator setpoint temperature;
providing a signal from the first PID controller ( 404 ) to the second PID controller ( 414 ) reprogramming the stator winding temperature setpoint, the stator winding temperature setpoint being dynamically calculated by the first PID controller ( 404 ) based on the signal from the motor housing temperature sensor indicative of the motor housing temperature and its variance from the motor housing temperature setpoint as a result of refrigerant flow to the motor cooling circuit.

2. The method of claim 1 wherein the step of providing a refrigeration circuit ( 1014 ) comprising a compressor ( 1020 ) having a motor further comprises providing a compressor selected from the group consisting of a centrifugal compressor, a screw compressor and a scroll compressor.

3. The method of claim 1 wherein the step of providing a motor cooling circuit that includes the compressor motor ( 170 ) including a stator ( 176 ) having windings and a rotor ( 178 ) mounted within a motor housing ( 174 ), further includes a spacer ( 180 ) positioned within the housing ( 174 ) and between the housing ( 174 ) and the stator ( 176 ).

4. The method of claim 3 wherein the motor housing ( 174 ) further includes a helical annulus ( 182 ) providing a fluid passageway from the motor inlet through the motor housing ( 174 ) for refrigerant.

5. The method of claim 3 wherein the spacer ( 182 ) comprises a highly thermally conductive material.

6. The method of claim 1 wherein the step of providing a motor cooling circuit further includes a motor cooling circuit in first fluid communication with the refrigeration circuit ( 1014 ) providing refrigerant liquid to the evaporator ( 1050 ) and in second fluid communication with the refrigerant circuit ( 1014 ) providing refrigerant gas to the evaporator ( 1050 ).

7. The method of claim 1 wherein the step of providing a signal indicative of the stator winding temperature to the second PID controller ( 414 ) is a stator winding temperature from a temperature sensor mounted on the stator windings.

8. The method of claim 1 wherein the step of providing a signal indicative of the stator winding temperature to the second PID controller ( 414 ) is an amperage drawn by the stator windings measured by a stator winding amperage meter.

9. A system for cooling a compressor motor in a refrigeration system ( 1014 ), the refrigeration system having a compressor ( 1020 ) driven by a motor ( 170 ) further comprising a stator ( 176 ) and windings positioned within a motor housing ( 174 ), a condenser ( 1030 ) in fluid communication with the compressor ( 1020 ), a first expansion valve ( 1040 ) in fluid communication with the condenser ( 1030 ), an evaporator ( 1050 ) in fluid communication with the first expansion valve ( 1040 ) and in fluid communication with the compressor ( 1020 ) and a motor cooling circuit further including a second expansion valve ( 1043 ) in fluid communication with the condenser ( 1030 ) and the compressor motor ( 170 ), the compressor motor further being in fluid communication with the refrigeration system ( 1014 ) between downstream of the first expansion valve ( 1040 ) and a compressor inlet, wherein the system is further characterized by:
a primary PID loop ( 402 ), the primary PID loop ( 402 ) including a compressor motor housing temperature sensor mounted on a surface of the motor housing, and a first PID controller ( 404 ) programmed with a motor housing temperature set point and in communication with the motor housing temperature sensor;
a secondary PID loop ( 412 ), the secondary PID loop ( 412 ) including a stator winding temperature measurement indicator and a second PID controller ( 414 ) in communication with the second expansion valve ( 1043 ) and with the first PID controller ( 404 ), the second PID controller ( 414 ) further programmed with a stator winding temperature measurement indicator set point;
the second PID controller ( 414 ) being in communication with the second expansion valve ( 1043 ) in response to a signal from the stator winding temperature measurement indicator to regulate a flow of refrigerant to the motor cooling circuit when the stator winding temperature measurement indicator indicates that the stator winding temperature varies from the stator winding temperature indicator set point;
the first PID controller ( 404 ) in communication with the motor housing temperature sensor and the second PID controller ( 414 ), the first PID controller ( 404 ) reprogramming the stator winding temperature indicator set point of second PID controller ( 414 ) based on the temperature of the motor housing ( 174 ) and its variance from the motor housing temperature setpoint as a result of refrigerant flow to the motor cooling circuit.

10. The system of claim 9 wherein the stator winding temperature measurement indicator is an amperage sensor measuring the current drawn by the stator windings.

11. The system of claim 9 wherein the stator winding temperature measurement indicator is a temperature sensor mounted on the windings.

12. The system of claim 9 wherein the compressor motor further includes a spacer positioned between the motor housing and the stator.

13. The system of claim 12 wherein the motor housing further includes as a passageway for refrigerant, a helical annulus ( 18

Assignees

• Johnson Controls Tech Co

Inventors

• Yang Liming
• Crane Curtis Christian

Classifications

• F25B31/006 Primary

  Cooling of compressor or motor · CPC title

• F25B2700/21157

  at the coil or rotor · CPC title

• F25B49/022

  Compressor control arrangements · CPC title

• F25B2700/21156

  of the motor · CPC title

• F25B31/008

  by injecting a liquid · CPC title