US 12,674,609 B2Granted

Compressor control band process for variable cascade refrigeration system

AssigneeTrane Technologies Life Sciences LLC

InventorsThomas A. Schoeppner, Alex Roberts, Trace A. Lydick

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Abstract

A method and apparatus for controlling compressors in a cascade vapor compression system. The process may include controlling the operation of a first compressor based on a constant band control, and controlling the operation of a second compressor based on a proportional band control. Controlling the first compressor based on the constant band control may include operating the compressor at a constant setting if first measurements are within a range associated with a first setpoint. It may also include proportionally adjusting the operation of the first compressor if the first measurements are outside the range. Further, controlling the second compressor based on the proportional band control may include operating the compressor based on one of a plurality of proportional bands, each proportional band having a different proportional factor. Controlling the second compressor operation may further include switching between these proportional bands based on a second measured parameter.

Claims20

Dependent claims

A method of controlling a cascade vapor compression system, the cascade vapor compression system including a first stage compressor configured to circulate refrigerant in a first stage refrigeration circuit, and a second stage compressor configured to circulate refrigerant in a second stage refrigeration circuit, the method comprising:

receiving first measurements over time indicative of a first parameter associated with the cascade vapor compression system;
receiving second measurements over time indicative of a second parameter associated with the second stage refrigeration circuit;
controlling a speed of the first stage compressor based on a constant band control, wherein controlling the first stage compressor based on the constant band control includes:
operating the first stage compressor at a constant speed setting upon determining that the first measurements are within a target parameter band, wherein the target parameter band is defined by a first setpoint and a band offset, and
adjusting the speed of the first stage compressor based on a proportional rate control upon determining that a portion of the first measurements is outside the target parameter band and within a first threshold and a second threshold;
and
controlling a speed of the second stage compressor based on a proportional band control, wherein controlling the speed of the second stage compressor based on the proportional band control is based on, in part, the second measurements and a second setpoint, the proportional band control further including a plurality of proportional bands, each of the plurality of proportional bands including a different proportional factor than any other proportional band in the plurality of proportional bands.

4 more elements

receiving first measurements over time indicative of a first parameter associated with the cascade vapor compression system;
receiving second measurements over time indicative of a second parameter associated with the second stage refrigeration circuit;
controlling a speed of the first stage compressor based on a constant band control, wherein controlling the speed of the first stage compressor based on the constant band control includes, in part, a comparison between the first measurements and a first setpoint, the constant band control further including a constant speed setting;
and
controlling a speed of the second stage compressor based on a proportional band control, wherein controlling the speed of the second stage compressor based on the proportional band control includes:
identifying an operating proportional band from a plurality of proportional bands, each of the plurality of proportional bands including a maximum operating speed, a minimum operating speed, and a proportional factor, wherein each of the plurality of proportional bands includes a different proportional factor than any other proportional band in the plurality of proportional bands, and
adjusting the speed of the second stage compressor based on the operating proportional band and the second measurements.

4 more elements

receiving first measurements over time indicative of a measured parameter associated with the cascade vapor compression system;
receiving second measurements over time indicative of a measured parameter associated with the second stage refrigeration circuit;
controlling a speed of the first stage compressor based on a constant band control, wherein controlling the first stage compressor based on the constant band control includes:
operating the first stage compressor at a constant speed setting upon determining that the first measurements are within a target parameter band, wherein the target parameter band is defined by a first setpoint and a band offset, and
adjusting the speed of the first stage compressor based on a proportional rate control upon determining that a portion of the first measurements is outside the target parameter band and within a first threshold and a second threshold;
and
controlling a speed of the second stage compressor based on a proportional band control, wherein controlling the speed of the second stage compressor based on the proportional band control includes:
identifying an operating proportional band from a plurality of proportional bands, each of the plurality of proportional bands including a maximum operating speed, a minimum operating speed, and a proportional factor, wherein each of the plurality of proportional bands includes a different proportional factor than any other proportional band in the plurality of proportional bands, and
adjusting the speed of the second stage compressor based on the operating proportional band and the second measurements.

6 more elements

Dependencies are inferred from the claim text.