CN108700359B

CN108700359B - Compressor capacity modulation system for multiple compressors

Info

Publication number: CN108700359B
Application number: CN201780013453.XA
Authority: CN
Inventors: 雅各布·A·格罗舍克
Original assignee: Emerson Climate Technologies Inc
Current assignee: Copeland LP
Priority date: 2016-02-19
Filing date: 2017-02-17
Publication date: 2021-01-01
Anticipated expiration: 2037-02-17
Also published as: CN108700359A; US20170241690A1; EP3417218A4; WO2017143261A1; EP3417218A1

Abstract

A system includes a plurality of compressors, an evaporator, an expansion device, and a system controller. The compressors may be coupled in parallel. The system controller may: determining a saturated evaporator temperature, a saturated condensing temperature, and a target capacity requirement; determining an estimated system capacity and an estimated power consumption for each compressor operating configuration; comparing the estimated system capacity to the target capacity requirement and the error tolerance value; selecting an optimal operating mode based on the comparison and based on the evaluated power consumption; and commanding activation and deactivation of the plurality of compressors to achieve the selected optimal operating mode. The optimal operating mode may be selected after normal system logic achieves steady state and may be selected from a group having an estimated system capacity and a lowest associated power consumption value within a tolerance of error of the target capacity requirement.

Description

Compressor capacity modulation system for multiple compressors

Cross Reference to Related Applications

This application claims priority from us utility patent application No.15/424,352 filed on 3/2/2017 and also claims benefit from us provisional application No.62/297,680 filed on 19/2/2016. The entire disclosure of the above application is incorporated herein by reference.

Technical Field

The present disclosure relates to compressor capacity modulation systems, and more particularly to a compressor capacity modulation system for multiple compressors that optimizes overall system efficiency.

Background

This section provides background information related to the present disclosure, but is not necessarily prior art.

Compressors are used in a wide variety of industrial and domestic applications to circulate a refrigerant within a refrigeration, heat pump, HVAC, or chiller system (commonly referred to as a "refrigeration system") to provide a desired heating and/or cooling effect. In any of the above systems, the compressor will provide consistent and efficient operation to ensure that the particular refrigeration system is operating properly.

The compressor system may include multiple stationary compressors coupled together for improved efficiency and capacity modulation. Compressors have the capability to operate together or independently, delivering several discrete capacity steps (capacity steps) as needed. System capacity can be adjusted by using multiple refrigeration circuits or by using multiple compressors in a single circuit. For example, in a four compressor system that is frequently used in a set of roofs, each compressor may be turned on and off to achieve a particular output. In other examples, such as for chillers, two to eight compressors are a typical number per unit, meaning that capacity levels of up to 12 can be achieved to match the load by cycling the compressors on and off, depending on the combination of unity or non-unity.

The fixed multiple compressors are started and shut down in the order in which they are connected to meet the capacity requirements for the system. The fixed multi-compressor will also be started in order of least run time to most run time. The compressor operates until a temperature (or other) threshold is reached. Based on the temperature position relative to the threshold, the last compressor is turned on and off to adjust the system capacity. Current multi-compressor systems look at meeting capacity requirements and may tend to cycle unnecessarily, often ignoring more efficient modes of operation.

Disclosure of Invention

This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

An example system includes a plurality of compressors, an evaporator, a condenser, and a system controller. Multiple compressors may be coupled in parallel by a common discharge line and a common suction line. The system controller may determine a saturated evaporator temperature of the evaporator, a saturated condensing temperature of the condenser, and target capacity requirements for the plurality of compressors. The system controller may determine an estimated system capacity and an estimated power consumption for each operating configuration of the plurality of compressors based on the saturated evaporator temperature and the saturated condensing temperature. The system controller may compare the estimated system capacity for each operating configuration to the target capacity requirement and the error tolerance value. The system controller may select an optimal operating mode for the plurality of compressors based on the comparison and based on the estimated power consumption for each operating configuration. The optimal operating mode may be selected from a set of operating configurations for which the estimated system capacity is within a tolerance of the error of the target capacity requirement, and the optimal operating mode has the lowest associated power consumption value in the set. The system controller may command activation and deactivation of the plurality of compressors to achieve the selected optimal operating mode.

The compressor system may also include a plurality of compressors having at least one fixed capacity compressor and at least one dual stage compressor.

The compressor system may also include at least one dual stage compressor including a compressor with a delayed suction system.

The compressor system may also include at least one dual-stage compressor including a compressor having a variable speed motor.

The compressor system may also include a plurality of compressors having variable volume ratio compressors.

The compressor system may also include at least one dual-stage compressor including a compressor having another capacity modulation scheme or a scroll separation system.

The compressor system may further include an estimated system capacity calculated based on characteristics of each of the plurality of compressors.

The compressor system may also include an operating configuration for the plurality of compressors, the operating configuration having a location for each of the plurality of compressors and a coefficient performance curve for each of the plurality of compressors.

The compressor system may also include a system controller that determines an estimated power consumption for each operating configuration based on a ten coefficient performance curve for each of the plurality of compressors in the associated operating configuration.

The compressor system may also include a system controller that determines an estimated system capacity for each operating configuration based on a ten-factor performance curve for each of the plurality of compressors in the associated operating configuration.

The compressor system may also include a system controller that determines whether the plurality of compressors have stabilized before selecting the optimal operating mode. The determination as to whether the plurality of compressors have stabilized may be based on an output value of at least one of a current sensor, a common suction line temperature sensor, a common discharge line temperature sensor, a common suction line pressure sensor, and a common discharge line pressure sensor.

The compressor system may also include a plurality of compressors including one two-stage compressor and two fixed capacity compressors having different capacities, and the plurality of compressors having eleven associated operating configurations.

The compressor system may also include a plurality of compressors including two fixed capacity compressors and one dual stage compressor, the two fixed capacity compressors and the one dual stage compressor having different capacities, and the plurality of compressors having seven associated operating configurations.

An example system includes a first circuit, a second circuit, and a system controller. The first circuit has a plurality of first compressors coupled in parallel by a first common discharge line and a first common suction line. The second circuit has a plurality of second compressors coupled in parallel by a second common discharge line and a second common suction line. A system controller determines an estimated system capacity and an estimated power consumption for each operating configuration of the plurality of compressors in the first circuit and the plurality of compressors in the second circuit based on the saturated evaporator temperature and the saturated condensing temperature. The system controller selects an optimal operating mode for the plurality of compressors in the first circuit and the plurality of compressors in the second circuit based on a comparison of the estimated system capacity for each operating configuration to the target capacity demand and the error tolerance value and based on the estimated power consumption for each operating configuration. The optimal operating mode is selected from a set of operating configurations for which the estimated system capacity is within a tolerance of the target capacity requirement and the optimal operating mode has the lowest associated power consumption value in the set. The system controller commands activation and deactivation of the plurality of compressors in the first circuit and the plurality of compressors in the second circuit to achieve the selected optimal operating mode. It should be understood that the system is not limited to two circuits, but that the compressor operating mode in any number of circuits may be controlled and optimized.

An example method for operating a system may include determining a saturated evaporator temperature of an evaporator, a saturated condensing temperature of a condenser, and target capacity requirements for a plurality of compressors; determining an estimated system capacity and an estimated power consumption for each operating configuration of the plurality of compressors based on the saturated evaporator temperature and the saturated condensing temperature; comparing the estimated system capacity for each operational configuration to a target capacity requirement and an error tolerance value; selecting an optimal operating mode for the plurality of compressors based on the comparison and based on the estimated power consumption for each operating configuration, the optimal operating mode being selected from a set of operating configurations for which the estimated system capacity is within a tolerance of error of the target capacity requirement, and the optimal operating mode having a lowest associated power consumption value in the set; and commanding activation and deactivation of the plurality of compressors to achieve the selected optimal operating mode.

The method further comprises the following steps: the plurality of compressors includes at least one of a fixed capacity compressor, a dual stage compressor, and a variable volume ratio compressor, wherein, if the plurality of compressors includes a dual stage compressor, the dual stage compressor includes at least one of a compressor having a delayed suction system, a compressor having a variable speed motor, and a compressor having a scroll separation system.

The method may also include calculating an estimated system capacity based on the operating configuration for the plurality of compressors.

The method may further comprise: the operating configuration for the plurality of compressors has a location for each of the plurality of compressors and a ten coefficient performance curve for each of the plurality of compressors.

The method may further comprise: the estimated power consumption for each operating configuration is determined based on a ten coefficient performance curve for each of the plurality of compressors in the associated operating configuration.

The method may further comprise: the estimated system capacity for each operating configuration is determined based on a ten-factor performance curve for each of the plurality of compressors in the associated operating configuration.

The method may further comprise: determining whether the plurality of compressors have stabilized before selecting the optimal operating mode, the determination as to whether the plurality of compressors have stabilized being based on an output value of at least one of a current sensor, a common suction line temperature sensor, a common discharge line temperature sensor, a common suction line pressure sensor, and a common discharge line pressure sensor.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

Drawings

The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

FIG. 1 is a schematic illustration of a compressor system according to the present disclosure;

FIG. 2 is a perspective view of a multi-compressor of the compressor system of FIG. 1;

FIG. 3 is a chart illustrating a plurality of operating modes for various compressor systems;

FIG. 4 is a table illustrating possible operating modes for a non-uniform three-piece compressor system;

FIG. 5 is a schematic diagram of a control system for the compressor system of FIG. 1;

FIG. 6 is an example pressure temperature graph for a compressor;

FIG. 7 is a flowchart illustrating steps for operating the compressor system of FIG. 1; and

FIG. 8 is a graph illustrating the effect of optimized fixed pressure ratio on the efficiency of a conventional fixed pressure ratio and variable valve ratio compressor system.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings.

Referring to FIG. 1, a compressor capacity modulation system 10 is provided. The compressor capacity modulation system 10 may be used in conjunction with a heating, ventilation, and air conditioning (HVAC) system or refrigeration system 12 that includes at least a multi-connected or multi-connected compressor 14, a condenser 18, and an evaporator 22. Although the refrigeration system 12 is depicted and described as including a multi-compressor 14, a condenser 18, and an evaporator 22, the refrigeration system 12 may include additional and/or alternative components (e.g., an expansion valve, for example only). Further, the present disclosure is applicable to various types of refrigeration systems including, but not limited to, heating, ventilation, and air conditioning (HVAC) systems, heat pump systems, refrigeration systems, and chiller systems.

During operation of the refrigeration system 12, the multi-compressor 14 circulates refrigerant generally between the condenser 18 and the evaporator 22 to produce a desired heating and/or cooling effect. Specifically, the multi-compressors 14 receive refrigerant in vapor form and compress the refrigerant. The multi-compressor 14 provides pressurized refrigerant in vapor form to the condenser 18.

All or a portion of the pressurized refrigerant received from the multi-compressor 14 may be converted to a liquid state within the condenser 18. Specifically, the condenser 18 transfers heat from the refrigerant to the ambient air, thereby cooling the refrigerant. When the refrigerant vapor cools to a temperature below the saturation temperature, the state of the refrigerant changes from vapor to liquid. Condenser 18 may include a condenser fan (not shown) that increases the rate at which heat is transferred away from the refrigerant by forcing air through a heat exchanger coil associated with condenser 18.

The refrigerant may pass through an expansion valve (not shown) that expands the refrigerant before reaching the evaporator 22. The evaporator 22 may receive a mixture of vapor refrigerant and liquid refrigerant from the condenser 18 or pure liquid refrigerant. The refrigerant absorbs heat in the evaporator 22. Therefore, when the temperature is raised to a temperature greater than or equal to the saturation temperature of the refrigerant, the state of the liquid refrigerant provided in the evaporator 22 changes from liquid to vapor. The evaporator 22 may include an evaporator fan (not shown) that increases the rate of heat transfer to the refrigerant by forcing air through a heat exchanger coil associated with the evaporator 22.

As the liquid refrigerant absorbs heat, ambient air disposed proximate the evaporator 22 is cooled. The evaporator 22 may be disposed within a space to be cooled, such as a building or a refrigerator, in which the cooling effect produced by the refrigerant absorbing heat is used to cool the space. The evaporator 22 may also be associated with a heat pump refrigeration system, wherein the evaporator 22 may be located remotely from the building so that the cooling effect is dissipated to the atmosphere, and the exhaust heat generated by the condenser 18 is directed to the interior of the space to be heated.

Referring additionally to fig. 2, the multi-compressors 14 may further include two or

more compressors

26, 30, 34 coupled in parallel. Each of the

compressors

26, 30, 34 of the multi-compressors 14 includes a plurality of solenoids 36 and contactors 38 that may be activated to control the compressors. For example only, where applicable, the solenoid 36 and contactor 38 may be activated to operate the compressor at full or partial capacity or load. By way of example only, three

compressors

26, 30, 34 are shown in fig. 1 and 2. Although three compressors are shown and described, it should be understood that any number of compressors including two compressors and more than three compressors may be included in the multi-compressor 14. The

compressors

26, 30, 34 share a single suction header or common suction line 40 and a single discharge header or common discharge line 42.

Although a single circuit of a multi-compressor is discussed and shown, it should be understood that multiple circuits may exist in a single system. Each circuit in the system includes its own multiple compressors coupled in two, three, four, or any other number. The circuits in a multi-circuit system are independent but can be operated by a common evaporator and a common condenser. The output can be adjusted by switching each loop on individually or in combination with other loops. Thus, the present disclosure is not limited to a single circuit of a multi-compressor, but may be applied to any number of multi-circuits, where each circuit has a multi-compressor.

The multi-compressor 14 may include one or more multi-stage compressors capable of operating at a plurality of different capacity levels. For example, a dual stage compressor capable of operating at full capacity or load (or full scroll volume ratio) and modulated capacity or load (with a lower scroll volume ratio) may be used. The multi-stage compressor may use any manner of capacity modulation, including but not limited to two-step capacity modulation or continuous capacity modulation. Two-step capacity modulation is where the compressor is operated at full capacity or load (e.g., 100% capacity) or partial capacity or load (e.g., 67% capacity) depending on cooling and/or heating requirements. For example, two-step capacity adjustment may be accomplished using a delayed suction system that adjusts the capacity of the compressor by venting the intermediate pressurization chamber to the suction chamber as described in U.S. Pat. No.6,821,092, the disclosure of which is incorporated herein by reference. The capacity of the compressor can be adjusted from 10% to 100% by continuous capacity adjustment or variable valve adjustment so that the output exactly matches the varying cooling requirements of the space. For example, the bypass valve and bypass passage may be used to continuously adjust compressor capacity without changing the speed of the motor. As another example, continuous capacity modulation may be achieved using a variable speed capacity modulation system that varies the speed of the compressor motor. The compressor motor speed determines the rate of refrigerant flow; thus, the capacity can be adjusted by changing the motor frequency. Thus, for a variable speed capacity modulation system, the capacity output increases and decreases with motor speed. As another example, continuous capacity modulation may be achieved using a vortex separation capacity modulation system. In a vortex separation capacity modulation system, capacity control is achieved by axially separating the vortex devices over a relatively small period of time. For example, a vortex separation capacity modulation system is described in U.S. Pat. No.6,213,731, which is incorporated herein by reference. Further, any continuous capacity modulation system may also operate in two non-continuous capacity steps to achieve two-step capacity modulation. The two-stage compressor has three different modes of operation or power due to its capacity modulation: off, full capacity or load, and regulated or reduced capacity or load.

The multi-compressor 14 may include a fixed capacity compressor. A fixed capacity compressor is a compressor having a conventional scroll design with a single standard built-in volume ratio (BIVR). Fixed capacity compressors have two different modes of operation or power: off, and full capacity or load.

The multi-compressors 14 may include variable volume ratio compressors. Variable volume ratio compressors include bypass passages to eliminate over-compression losses by introducing compressed fluid into the fixed scroll of the compressor through a bypass valve. Variable volume ratio compressors have three different modes of operation or power: off, full BIVR and capacity, and reduced swirl volume ratio. The variable volume ratio compressor may be a passive solution or any other solution. While variable volume ratio compressors can be passive solutions in terms of control, variable volume ratio compressors add additional complexity by adjusting the scroll volume ratio to meet demand. In a multi-compressor, knowing which compressors have a variable volume ratio design and selectively switching them on and off can affect the overall system efficiency (see fig. 8, discussed in further detail below). Variable volume ratio compressors can provide higher efficiency over a larger system pressure range than compressors with optimized or conventional fixed pressure ratios. As shown in fig. 8, the pressure ratio is calculated as the discharge pressure divided by the suction pressure.

The multi-compressor 14 may be a unified multi-compressor or a compressor with non-unified multi-compressors coupled in parallel. The uniform multi-compressors are parallel compressors with the same BIVR and capacity; while a non-uniform multi-compressor is a parallel compressor with different BIVRs and/or capacities. The multi-compressor 14 may also include one or more of a two-stage compressor, a fixed capacity compressor, and a variable capacity ratio compressor.

Referring now to fig. 3, in some embodiments, the multi-compressor 14 may be a uniform two-piece fixed capacity compressor, meaning that the multi-compressor 14 may include two fixed capacity compressors with the same BIVR and capacity coupled in parallel. Due to the two modes of operation of each of the two fixed capacity compressors, and the fact that the two fixed capacity compressors have the same BIVR and capacity, the identical two-piece fixed capacity compressor has a total of two possible modes of operation or power in addition to the mode of operation in which all of the compressors are off, namely: (1) a compressor is switched on; and (2) both compressors are on.

In other embodiments, the multi-compressors 14 may be uniform three-piece fixed capacity compressors, meaning that the multi-compressors 14 may include three fixed capacity compressors with the same BIVR and capacity coupled in parallel. Due to the two modes of operation of each of the three fixed capacity compressors, and the fact that the three fixed capacity compressors have the same BIVR and capacity, the consistent three-piece fixed capacity compressor has a total of three possible modes of operation or power in addition to the mode of operation in which all of the compressors are off, namely: (1) a compressor is switched on; (2) the two compressors are switched on; and (3) three compressors on.

In other embodiments, the multi-compressor 14 may be a non-uniform two-piece fixed capacity compressor, meaning that the multi-compressor 14 may include two fixed capacity compressors with different BIVRs and capacities coupled in parallel. Due to the two modes of operation of each of the two fixed capacity compressors, and the fact that the two fixed capacity compressors have different BIVRs and capacities, the non-uniform two-piece fixed capacity compressor has a total of three possible modes of operation or power in addition to the mode of operation in which all compressors are off, namely: (1) the lower capacity compressor is on; (2) the higher capacity compressor is on; and (3) both compressors are on.

In other embodiments, the multi-compressors 14 may be non-uniform three-piece fixed capacity compressors, meaning that the multi-compressors 14 may include three fixed capacity compressors with different BIVRs and capacities coupled in parallel. Due to the two modes of operation of each of the three fixed capacity compressors, and the fact that the three fixed capacity compressors have different BIVRs and capacities, the non-uniform three-piece fixed capacity compressor has a total of seven possible modes of operation or power in addition to the mode of operation in which all compressors are off, namely: (1) the lowest capacity compressor is switched on; (2) switching on the medium-capacity compressor; (3) the highest capacity compressor is switched on; (4) the lowest capacity compressor is connected with the medium capacity compressor; (5) the lowest capacity compressor and the highest capacity compressor are switched on; and (6) the medium capacity compressor and the maximum capacity compressor are on; (7) all three compressors are on.

In other embodiments, the multi-compressor 14 may be a uniform two-piece two-stage compressor, meaning that the multi-compressor 14 may include one two-stage compressor and one fixed capacity compressor, where the two compressors coupled in parallel have the same BIVR and capacity. Due to the three modes of operation of the two-stage compressor and the two modes of operation of the fixed capacity compressor, and the fact that the two-stage compressor and the fixed capacity compressor have the same BIVR and capacity, the unified two-piece two-stage compressor has a total of four possible modes of operation or power in addition to the mode of operation with all compressors off, i.e., the four modes of operation or power are: (1) a fixed capacity compressor on (or a two-stage compressor on at high capacity); (2) the two-stage compressor is switched on at low capacity; (3) the fixed capacity compressor is on and the two-stage compressor is on at low capacity; and (4) the fixed capacity compressor is on and the two-stage compressor is on at high capacity.

In other embodiments, the multi-compressor 14 may be a uniform three-piece two-stage compressor, meaning that the multi-compressor 14 may include one two-stage compressor and two fixed capacity compressors coupled in parallel with the same BIVR and capacity. Due to the three modes of operation of the two-stage compressor and the two modes of operation of each of the fixed capacity compressors, and the fact that the two-stage compressor and the fixed capacity compressor have the same BIVR and capacity, the consistent three-piece two-stage compressor has a total of six possible modes of operation or power in addition to the mode of operation in which all compressors are off, i.e., the six modes of operation or power are: (1) either fixed capacity compressor is on (or the dual stage compressor is on at high capacity); (2) the two-stage compressor is switched on at low capacity; (3) one fixed capacity compressor is on and the two-stage compressor is on at low capacity; (4) two fixed capacity compressors are on (or one fixed capacity compressor is on and the two-stage compressor is on at high capacity); (5) two fixed capacity compressors are on and the two-stage compressor is on at low capacity; and (6) two fixed capacity compressors are on and the two-stage compressor is on at high capacity.

In other embodiments, the multi-compressor 14 may be a non-uniform two-piece two-stage compressor, meaning that the multi-compressor 14 may include one two-stage compressor and one fixed capacity compressor with different BIVRs and capacities coupled in parallel. Due to the three modes of operation of the two-stage compressor and the two modes of operation of the fixed capacity compressor, and the fact that the two-stage compressor and the fixed capacity compressor have different BIVRs and capacities, the non-uniform two-piece two-stage compressor has a total of five possible modes of operation or power in addition to the mode of operation in which all compressors are off: (1) the two-stage compressor is switched on at low capacity; (2) switching on a fixed-capacity compressor; (3) the two-stage compressor is switched on at high capacity; (4) the fixed capacity compressor is on and the two-stage compressor is on at low capacity; and (5) the fixed capacity compressor is on and the two-stage compressor is on at high capacity.

In other embodiments, the multi-compressor 14 may be a non-uniform three-piece two-stage compressor, meaning that the multi-compressor 14 may include one two-stage compressor and two fixed capacity compressors coupled in parallel with different BIVRs and capacities. Due to the three operating modes of the two-stage compressor and the two operating modes of each of the fixed capacity compressors, and the fact that the two-stage compressor and the fixed capacity technology compressor have different BIVRs and capacities, the non-uniform three-piece two-stage compressor has a total of eleven possible operating or power modes in addition to the operating mode in which all compressors are off: (1) the lower capacity fixed compressor is on; (2) the higher capacity fixed compressor is on; (3) the two-stage compressor is switched on at low capacity; (4) the two-stage compressor is switched on at high capacity; (5) the lower capacity fixed compressor is on and the higher capacity fixed compressor is on; (6) the lower capacity fixed compressor is on and the two-stage compressor is on at low capacity; (7) the lower capacity fixed compressor is on and the two-stage compressor is on at high capacity; (8) the higher capacity fixed compressor is on and the two-stage compressor is on at low capacity; (9) the higher capacity fixed compressor is on and the two-stage compressor is on at high capacity; (10) the lower capacity fixed compressor is on, the higher capacity fixed compressor is on, and the two-stage compressor is on at low capacity; and (11) the lower capacity fixed compressor is on, the higher capacity fixed compressor is on, and the two-stage compressor is on at high capacity.

In other embodiments, the multi-compressor 14 may be a three-piece non-uniform two-stage compressor including three two-stage compressors with different BIVRs and capacities coupled in parallel. Due to the three operating modes of each of the three two-stage compressors, and the fact that the two-stage compressors have different BIVRs and capacities, the three-piece two-stage compressor has a total of twenty-six possible operating or power modes in addition to the operating mode in which all of the compressors are off: (1) the lower capacity two-stage compressor is switched on at high capacity; (2) the lower capacity two-stage compressor is switched on at low capacity; (3) the medium capacity two-stage compressor is switched on at high capacity; (4) the medium capacity two-stage compressor is switched on at low capacity; (5) the higher capacity two-stage compressor is switched on at high capacity; (6) the higher capacity two-stage compressor is switched on at low capacity; (7) the lower capacity two-stage compressor and the medium capacity two-stage compressor are switched on at high capacity; (8) the lower capacity two-stage compressor and the medium capacity two-stage compressor are switched on at low capacity; (9) the lower capacity two-stage compressor is on at high capacity and the medium capacity two-stage compressor is on at low capacity; (10) the lower capacity two-stage compressor is on at low capacity and the medium capacity two-stage compressor is on at high capacity; (11) the lower capacity two-stage compressor and the higher capacity two-stage compressor are switched on at high capacity; (12) the lower capacity two-stage compressor and the higher capacity two-stage compressor are switched on at low capacity; (13) the lower capacity two-stage compressor is on at high capacity and the high capacity two-stage compressor is on at low capacity; (14) the lower capacity two-stage compressor is on at low capacity and the high capacity two-stage compressor is on at high capacity; (15) the medium capacity two-stage compressor and the higher capacity compressor are switched on at high capacity; (16) the medium-capacity two-stage compressor and the higher-capacity two-stage compressor are switched on at a low capacity; (17) the medium capacity two-stage compressor is switched on at high capacity and the high capacity two-stage compressor is switched on at low capacity; (18) the medium capacity two-stage compressor is switched on at low capacity and the high capacity two-stage compressor is switched on at high capacity; (19) the lower capacity, medium capacity, and higher capacity two-stage compressors are switched on at high capacity; (20) the lower capacity, medium capacity and high capacity two-stage compressors are switched on at low capacity; (21) the lower and medium capacity two-stage compressors are switched on at high capacity and at lower capacity than the high capacity two-stage compressor; (22) the lower and higher capacity two-stage compressors are switched on at high capacity and the medium capacity two-stage compressor is switched on at low capacity; (23) the medium and higher capacity two-stage compressors are switched on at high capacity and the lower capacity two-stage compressor is switched on at low capacity; (24) the lower and medium capacity two-stage compressors are switched on at low capacity and the higher capacity two-stage compressor is switched on at high capacity; (25) the lower and higher capacity two-stage compressors are switched on at low capacity and the medium capacity two-stage compressor is switched on at high capacity; and (26) the medium capacity two-stage compressor and the higher capacity two-stage compressor are on at low capacity and the lower capacity two-stage compressor is on at high capacity.

Referring now to fig. 4, the total possible operating modes are determined based on the number of possible operating modes for each of the compressors and whether the compressors have the same or different BIVRs and capacities. For example, the non-uniform three-piece two-stage compressor shown in FIG. 4 has one two-stage compressor coupled in parallel (e.g., a two-stage compressor with a capacity of 83,000 BTU/hr) and two fixed capacity compressors with different BIVRs and capacities (e.g., a fixed capacity compressor with a capacity of 76,000BTU/hr and a fixed capacity compressor with a capacity of 91,000 BTU/hr). With this combination of compressors, there are a total of eleven possible operating modes, as shown in row 11 of fig. 4. Each possible mode of operation is indicated in fig. 4. Referring to the symbol table (Key), the dual stage compressor may be at off (0), full BIVR and capacity or load (1), or lower or regulated capacity or load (-1). Each of the fixed capacity compressors may be at off (0) or full BIVR and capacity or load (1). Thus, different combinations of compressor on/off/modulation modes are combined to form a total of eleven possible operating modes in addition to the one in which all compressors are off.

Although a fixed capacity uniform two-piece compressor, a fixed capacity uniform three-piece compressor, a fixed capacity non-uniform two-piece compressor, a fixed capacity non-uniform three-piece compressor, a two-stage uniform two-piece compressor, a two-stage uniform three-piece compressor, a two-stage non-uniform two-piece compressor, and a two-stage non-uniform three-piece compressor have been discussed above, it is to be understood that any combination of two-stage compressors, multi-stage compressors, fixed capacity compressors, and variable valve compressors may be used in parallel combination in the multi-compressors 14. The total number of possible operating modes of the multi-compressors 14 is determined based on the number of possible operating modes of each of the compressors and whether the compressors have the same or different full BIVR and capacity.

Referring to fig. 1, 2, and 5, a system controller 46 may be associated with the compressor capacity modulation system 10 and/or the multi-compressors 14 and may command each of the compressors in the multi-compressors 14 and/or the refrigeration systems 12 to start, stabilize, shut down, increase capacity, and decrease capacity. The system controller 46 may utilize a series of sensors to determine both measured and non-measured operating parameters of the compressor 14 and/or the refrigeration system 12. Although the system controller 46 is shown as being associated with the multi-compressors 14, the system controller 46 may be located anywhere within the refrigeration system 12 or outside of the refrigeration system 12. The system controller 46 may use the non-measured operating parameters in combination with the measured operating parameters to instruct the multi-compressor 14 and/or each compressor in the refrigeration system 12 to start, stabilize, shut down, increase capacity, and decrease capacity.

The system controller 46 may receive the common discharge line temperature to determine stabilization of the compressors in the multi-compressor 14, as described further below. The system controller 46 may also communicate with various sensors to determine the stability of the multi-compressor. For example, the stabilization may be determined by a current sensor 50 that measures the motor current of each of the compressors in the multi-compressors 14. Stabilization can also be determined by suction line temperature. A suction line temperature sensor 54 may be disposed in the suction line to the multi-compressor 14. The common discharge-line temperature may be sensed directly from the discharge line exiting the multi-compressor 14 by the discharge-line temperature sensor 58, and the system controller may look for a steady-going discharge-line temperature signal and/or a signal derivative value that goes to zero. Similarly, when stabilization of the multi-compressor is determined by the output of the current sensor 50 or the suction line temperature sensor 54, the system controller 46 will look for a signal that stabilization is proceeding and/or a signal derivative value that goes to zero.

The system controller 46 may also receive compressor operating conditions such as saturated evaporator temperature (Ts) and saturated condensing temperature (Tc). The saturated evaporator temperature and the saturated condensing temperature may be sensed directly from the temperature sensor 62 in the evaporator 22 and the temperature sensor 66 in the condenser 18, respectively. The saturated evaporator temperature and the saturated condensing temperature may also be determined by the pressures sensed by the pressure sensor 70 at the evaporator 22 and the pressure sensor 74 at the condenser 18, respectively. The condensing pressure sensed by the pressure sensor 74 is the pressure at which the refrigerant changes phase from vapor to liquid. The evaporation pressure sensed by the pressure sensor 70 is the pressure at which the refrigerant changes phase from liquid to vapor.

For example only, the saturated evaporator temperature may be directly related to the saturated evaporator pressure, and the saturated condensing temperature may be directly related to the saturated condensing pressure. FIG. 6 provides an example graph relating pressure to temperature for various refrigerant types. Thus, the system controller 46 may determine the saturated evaporator temperature and the saturated condensing temperature by looking up the sensed values in a table stored in the memory 78 within the system controller 46.

The system controller 46 may also store a ten-factor performance model in the memory 78 for each of the compressors in the multi-compressors 14. The ten coefficient performance model is determined by the manufacturer or installer and describes the operating characteristics of the compressor. The ten coefficient performance model may be entered into memory 78 through user interface 82 during installation or inspection or at the completion of manufacture. The ten coefficient performance model is compressor model and size specific and published by the compressor manufacturer. The compressor capacity can be calculated by means of the ten-factor performance curve equation of the ARI (Air-Conditioning and Refrigeration Institute), the Air-Conditioning, Heating and Refrigeration Institute of today:

X＝C0+(C1*S)+(C2*D)+(C3*S²)+(C4*S*D)+(C5*D²)+(C6*S³)+(C7*D*S²)+(C8*S*D²)+(C9*D³)

wherein X is the capacity (BTU/HR) or power (watts or amperes), S is the saturated evaporation temperature, and D is the saturated condensation temperature.

Although a ten coefficient performance model is discussed, it should be understood that different coefficient characterizations may be applied. For example, the compressor may be modeled based on a twenty coefficient system. The present disclosure is not limited to a ten coefficient performance model, but may implement any compressor characterization scheme, such as a ten coefficient scheme, a twenty coefficient scheme, or any other number of coefficient schemes.

The location or configuration of each compressor in the multi-compressors 14 is also stored in the memory 78. For example, referring additionally to fig. 1, 2, and 4, if the multi-compressor 14 is arranged in the order of the two-stage compressor, the fixed capacity compressor 1, and the fixed capacity compressor 2, the two-stage compressor may be assigned the a position, the fixed capacity compressor 1 may be assigned the B position, and the fixed capacity compressor 2 may be assigned the C position. Thus, the memory 78 stores an identification and a location or configuration of each of the compressors in the multi-compressors 14.

The system controller 46 receives input of sensor data or calculates from the sensor data a common discharge line temperature, saturated evaporator temperature, saturated condensing temperature, ten coefficient performance model or curve, and identification and location of each of the compressors in the multi-compressors 14. Based on this data, the system controller 46 commands start-up, stabilization, shut-down, capacity increase, and capacity decrease of the multi-compressors 14.

The system controller 46 may include processing circuitry 86 for performing the functions of the method 100 for regulating compressor capacity. Referring now to fig. 5 and 7, the system controller 46 receives a request for target system capacity (or capacity demand) in step 104. For example, the target system capacity may be calculated or determined based on a comparison of a current temperature within the air conditioning or refrigerated space and a target temperature within the air conditioning or refrigerated space. As another example, the target system capacity may be calculated or determined based on a comparison of the current refrigerant temperature or pressure to the target refrigerant temperature or pressure. In step 108, the processing circuitry 86 may command the start-up of one or more of the

compressors

26, 30, 34 of the multi-compressors 14 based on the capacity demand or the request for the target system capacity. In step 112, once the compressors in the multi-compressors 14 are running, the processing circuitry 86 may wait and determine a steady state of the

active compressors

26, 30, 34 in the multi-compressors 14.

The steady/start-up state follows a defined start-up procedure, which causes each of the

compressors

26, 30, 34 in the multi-compressor 14 to be switched on one at a time to limit the inrush current (inrush current). For example, a single compressor of maximum capacity may be started first. The remaining compressors may be started in order of maximum capacity to minimum capacity until the target system capacity is met. The steady/start state of the multi-connected compressor 14 is initiated by a first command signal from the system controller 46 and ends with a steady state operation of the activated compressor in the multi-connected compressor 14. Steady state operation is determined by monitoring the derivative value of the exhaust line temperature over time and waiting for the derivative value to approach a low value or threshold during a set period of time. For example only, where the derivative value (discharge line temperature change) is less than three degrees Fahrenheit (F.) of discharge line temperature in two minutes, a steady or steady state may be determined. Thus, the target threshold may be three degrees Fahrenheit (F.). However, it should be understood that the target threshold may vary with each different system or application type. Some systems stabilize faster than others. For example, if the system uses an electronic expansion valve instead of a conventional thermal expansion valve (TXV), the electronic expansion valve system will stabilize faster than a conventional system with a TXV. Thus, while an example of three degrees Fahrenheit (° F) is provided, different target thresholds may be employed to determine steady or steady state operation for different system and application types.

As described above, the system controller 46 may determine the stability of the

compressors

26, 30, 34 in the multi-compressor 14 by monitoring the common discharge line temperature. The system controller 46 may communicate with the discharge line temperature sensor 58 to receive the common discharge line temperature. Alternatively, stabilization may be determined from the signal output of the current sensor 50 or the signal output of the suction line temperature sensor 54. The system controller 46 may determine: the multi-compressor 14 has stabilized when the discharge line temperature, the signal from the current sensor 50, or the signal from the suction line temperature sensor 54 becomes stable and/or the derivative value of the temperature or current signal becomes zero.

The processing circuitry 86 is in communication with the memory 78 and may receive the ten-factor performance model and the identification and location of each

compressor

26, 30, 34 in the multi-compressors 14 from the memory 78. At step 116, based on the inputs, the processing circuitry 86 may determine a currently Estimated System Capacity (ESC) for the enabled compressors in the multi-connected compressor 14 based on the current saturated evaporator temperature, the saturated condensing temperature, and the applicable ten-factor performance model for the current set of enabled compressors in the multi-connected compressor 14. The estimated system capacity may be the same or similar to the target capacity or capacity requirement from step 104. For example only, the estimated system capacity or target capacity may be determined from a ten-factor performance model and the previously described compressor efficiency formula.

Processing circuitry 86 may receive the common exhaust line temperature, the saturated evaporator temperature, and the saturated condensing temperature from various sensors, or may calculate the common exhaust line temperature, the saturated evaporator temperature, and the saturated condensing temperature from other received sensor data as previously described. The processing circuitry 86 may then determine an estimated compressor capacity and associated estimated power consumption value for all applicable operating modes of the multi-compressor 14 based on the various inputs at step 120. For example only, compressor capacity may be calculated using a ten-factor performance model for estimating compressor capacity and power consumption. As described above with reference to fig. 3, each independent operating mode includes a combination of enabled compressors, including any two-stage compressor operating at a particular operating level. The processing circuitry 86 uses a ten-factor performance model for capacity and power to calculate an estimated capacity and an estimated power consumption for each independent mode of operation associated with the multi-compressor 14. For example, as shown in fig. 3, a non-uniform three-piece compressor has eleven associated operating modes. In this case, the processing circuitry will use a ten-factor performance model for the non-uniform three-piece compressor to calculate the estimated capacity and estimated power consumption for each of the eleven operating modes.

At step 124, processing circuitry 86 receives the capacity Error Tolerance (ET) from memory 78. The ET may be stored in memory and initially set by the installer or manufacturer. The ET may also be modified by the user of the system. Processing circuitry 86 then compares the estimated capacity value for each individual operating mode with the target capacity and disregards at step 128 all modes having estimated capacity values that are outside the range of the target system capacity plus or minus the Error Tolerance (ET). In other words, any mode of operation that has an estimated capacity value that does not fall within the Error Tolerance (ET) of the target system capacity is not considered.

At step 132, the processing circuitry 86 analyzes the power values for the remaining operating modes under consideration and selects the operating mode with the lowest estimated power consumption value from the operating modes not excluded in step 128. The lowest power mode among the modes that satisfies the evaluation system capacity is the optimal mode because the lowest power mode satisfies the target capacity plus/minus Error Tolerance (ET) while using the minimum amount of power. In other words, the optimal operation mode corresponds to a configuration of the multi-connected compressor 14 that can satisfy the target capacity while consuming the minimum amount of power.

At step 136, the processing circuitry 86 activates the contactors 38 and solenoids 36 of the multi-split compressor 14 as needed to achieve the optimal mode or state. As discussed above, the optimum state will meet the capacity demand at the lowest power mode. In some cases, the current operating mode of the multi-connected compressor 14 may already correspond to the optimal operating mode. In this case, the processing circuitry 86 would not need to activate or deactivate any of the compressors, or change the capacity level of any of the dual-stage compressors, to achieve the optimal operating mode. In other cases, the current mode of operation may be different from the optimal mode of operation. In this case, the processing circuitry 86 activates or deactivates the compressors as needed and commands any dual stage compressor to operate at the appropriate capacity level to achieve the optimal operating mode.

At step 140, the processing circuitry 86 waits and determines stabilization of the multi-compressor. For example, the processing circuitry waits until the derivative value of the discharge line temperature leaving the multi-compressors 14 is close to steady. For example only, when the derivative value approaches a low value or threshold for a set period of time (only, for example, the derivative value is less than three degrees Fahrenheit (F.) in two minutes), the derivative value of the discharge line temperature stabilizes. When the derivative value of the discharge line temperature approaches stability, the multi-compressor 14 is operated in an optimal state. The optimized or optimized state optimizes compressor regulation to meet capacity demands from the refrigeration system 12 and optimizes performance of the multi-compressors 14 by reducing power consumption.

At step 144, the system controller 46 may command the processing circuitry 86 to stop the compressors in the multi-compressors 14 when the demand for capacity has been eliminated. For example, once a target temperature within a cooled or refrigerated space has been reached, the system may eliminate the need for cooling. The processing circuitry 86 then follows a pre-programmed power stop routine. The processing circuitry 86 will stop the compressors in the multi-compressors 14 one at a time. For example only, the compressors may be stopped in order of highest capacity compressor to lowest capacity compressor. In another example, the compressor may be turned off in order of position, first turning off C, then B, then a.

Based on the cooling demand, instead of proceeding to step 144, the system controller 46 may command a new capacity. In this case, the processing circuitry will then return to step 104 and start the optimization algorithm again.

Example embodiments are provided so that this disclosure will be thorough and will fully convey the scope to those skilled in the art. Numerous specific details are set forth, such as examples of specific components, devices, and methods, in order to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those of ordinary skill in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither the specific details nor the example embodiments should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "comprising," "including," and "having," are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It should also be understood that additional steps or alternative steps may be employed.

Although the terms "first," "second," and "third," etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first," "second," and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

For ease of description, spatially relative terms such as "inner," "outer," "below …," "below …," "below," "over …," "over," and the like may be used herein to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the example term "below …" can include both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

In this application, including the following definitions, the term controller or the term module may be replaced by the term circuit. The term controller or the term module may refer to, be part of, or include the following: an Application Specific Integrated Circuit (ASIC); digital, analog, or hybrid analog/digital discrete circuits; digital, analog, or hybrid analog/digital integrated circuits; a combinational logic circuit; a Field Programmable Gate Array (FPGA); a processor (shared, dedicated, or group) that executes code; a memory (shared, dedicated, or group) that stores code executed by the processor; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system on a chip.

The term code, as used above, may include software, firmware, and/or microcode, and may refer to programs, routines, functions, classes, and/or objects. The term shared processor includes a single processor that executes some or all code from multiple modules. The term group processor includes processors that execute some or all code from one or more modules in conjunction with additional processors. The term shared memory includes a single memory that stores some or all code from multiple modules. The term group memory includes memory that stores some or all code from one or more modules in conjunction with additional memory. The term memory is a subset of the term computer readable medium. The term computer-readable medium does not include transitory electrical or electromagnetic signals propagating through a medium, and thus, the term computer-readable medium may be considered tangible and non-transitory. Non-limiting examples of the non-transitory tangible computer readable medium include non-volatile memory, magnetic storage, and optical storage.

The apparatus and methods described herein may be partially or fully implemented by one or more computer programs executed by one or more memories. The computer program includes processor-executable instructions stored on at least one non-transitory tangible computer-readable medium. The computer program may also comprise or rely on stored data.

The foregoing description of the embodiments has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, although not specifically shown or described, where applicable, and may be interchanged and used in a selected embodiment. The individual elements or features may also be varied in a number of ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

1. A system, comprising:

a plurality of compressors coupled in parallel by a common discharge line and a common suction line;

an evaporator;

a condenser; and

a system controller that determines a saturated evaporator temperature of the evaporator, a saturated condensing temperature of the condenser, a target capacity demand for the plurality of compressors, and an estimated system capacity and an estimated power consumption for each operating configuration of the plurality of compressors based on the saturated evaporator temperature and the saturated condensing temperature;

wherein the system controller compares the estimated system capacity for each operating configuration to the target capacity requirement and error tolerance value, and selects an optimal operating mode for the plurality of compressors based on the comparison and the estimated power consumption for each operating configuration, the optimal operating mode being selected from a group of operating configurations for which the estimated system capacity is within error tolerance of the target capacity requirement, and the optimal operating mode having a lowest associated power consumption value in the group; and is

Wherein the system controller commands activation and deactivation of the plurality of compressors to achieve the selected optimal operating mode.

2. The system of claim 1, wherein the plurality of compressors has at least one fixed capacity compressor and at least one dual stage compressor.

3. The system of claim 2, wherein the at least one dual stage compressor comprises a compressor having a delayed suction system.

4. The system of claim 2, wherein the at least one dual stage compressor comprises a compressor having a variable speed motor.

5. The system of claim 2, wherein the at least one dual stage compressor comprises a compressor having a scroll separation system.

6. The system of claim 1, wherein the plurality of compressors have variable volume ratio compressors.

7. The system of claim 1, wherein the estimated system capacity is calculated based on characteristics of each compressor of the plurality of compressors.

8. The system of claim 1, wherein the operating configuration for the plurality of compressors includes a position of each compressor of the plurality of compressors and a coefficient performance curve for each compressor of the plurality of compressors.

9. The system of claim 1, wherein the system controller determines the estimated power consumption for each operating configuration based on a ten coefficient performance curve for each of the plurality of compressors in the associated operating configuration.

10. The system of claim 1, wherein the system controller determines the estimated system capacity for each operating configuration based on a ten coefficient performance curve for each of the plurality of compressors in the associated operating configuration.

11. The system of claim 1, wherein the system controller determines whether the plurality of compressors have stabilized prior to selecting the optimal operating mode, the determination as to whether the plurality of compressors have stabilized being based on an output value of at least one of a current sensor, a common suction line temperature sensor, a common discharge line temperature sensor, a common suction line pressure sensor, and a common discharge line pressure sensor.

12. The system of claim 1, wherein the plurality of compressors includes one dual stage compressor and two fixed capacity compressors of different capacities, and the plurality of compressors have eleven associated operating configurations.

13. The system of claim 1, wherein the plurality of compressors includes two fixed capacity compressors and one dual stage compressor, wherein the two fixed capacity compressors and the one dual stage compressor have different capacities and the plurality of compressors have seven associated operating configurations.

14. A system, comprising:

a first circuit having a plurality of first compressors coupled in parallel by a first common discharge line and a first common suction line;

a second circuit having a plurality of second compressors coupled in parallel by a second common discharge line and a second common suction line; and

a system controller that determines an estimated system capacity and an estimated power consumption for each operating configuration of the plurality of compressors in the first circuit and the plurality of compressors in the second circuit based on a saturated evaporator temperature and a saturated condensing temperature;

wherein the system controller selects an optimal operating mode for the plurality of compressors in the first circuit and the plurality of compressors in the second circuit based on the comparison of the estimated system capacity for each operating configuration to a target capacity demand and an error tolerance value and based on the estimated power consumption for each operating configuration, the optimal operating mode being selected from a set of operating configurations for which the estimated system capacity is within the error tolerance of the target capacity demand and the optimal operating mode having a lowest associated power consumption value in the set; and is

Wherein the system controller commands activation and deactivation of the plurality of compressors in the first circuit and the plurality of compressors in the second circuit to achieve the selected optimal operating mode.

15. A method for operating a system, comprising:

determining a saturated evaporator temperature of the evaporator, a saturated condensing temperature of the condenser, and a target capacity demand for the plurality of compressors;

determining an estimated system capacity and an estimated power consumption for each operating configuration of the plurality of compressors based on the saturated evaporator temperature and the saturated condensing temperature;

comparing the estimated system capacity for each operational configuration to the target capacity requirement and error tolerance value;

selecting an optimal operating mode for the plurality of compressors based on the comparison and based on the estimated power consumption for each operating configuration, the optimal operating mode being selected from a set of operating configurations for which the estimated system capacity is within a tolerance of error of the target capacity requirement, and the optimal operating mode having a lowest associated power consumption value in the set; and

commanding activation and deactivation of the plurality of compressors to achieve the selected optimal operating mode.

16. The method of claim 15, wherein the plurality of compressors comprises at least one of a fixed capacity compressor, a dual stage compressor, and a variable volume ratio compressor, wherein if the plurality of compressors comprises a dual stage compressor, the dual stage compressor comprises at least one of a compressor with a delayed suction system, a compressor with a variable speed motor, and a compressor with a scroll separation system.

17. The method of claim 15, further comprising calculating the estimated system capacity based on the operating configuration for the plurality of compressors.

18. The method of claim 17, wherein the operating configuration for the plurality of compressors includes a position of each compressor of the plurality of compressors and a ten-factor performance curve for each compressor of the plurality of compressors.

19. The method of claim 15, further comprising determining the estimated power consumption for each operating configuration based on a ten coefficient performance curve for each compressor of a plurality of compressors in an associated operating configuration.

20. The method of claim 15, further comprising determining the estimated system capacity for each operating configuration based on a ten coefficient performance curve for each compressor of a plurality of compressors in an associated operating configuration.

21. The method of claim 15, further comprising determining whether the plurality of compressors have stabilized prior to selecting the optimal operating mode, the determination as to whether the plurality of compressors have stabilized being based on an output value of at least one of a current sensor, a common suction line temperature sensor, a common discharge line temperature sensor, a common suction line pressure sensor, and a common discharge line pressure sensor.