Patent Description:
Refrigeration systems can be used to regulate the environment within an enclosed space. Various types of refrigeration systems, such as residential and commercial, may be used to maintain cold temperatures within an enclosed space such as a refrigerated case. To maintain cold temperatures within refrigerated cases, refrigeration systems control the temperature and pressure of refrigerant as it moves through the refrigeration system. When the system suffers from a power outage, the system can no longer refrigerate the enclosed space or keep its components cool. If heating occurs, this may create issues with the components that may damage the system or degrade system performance. <CIT> discloses a heat pump provided with a motor driven by input power, a first compressor mechanically connected to the motor, a first heat exchanger for exchanging heat between water and compressed air compressed by the first compressor, and a first hot water outlet for removing water heated by heat exchange in the first heat exchanger. <CIT> discloses a load shifting control system for selectively allocating a plurality of discrete electrical loads between a first power source and a second power source, including a plurality of transfer switches connected to respective electrical loads and further including a processor coupled with the transfer switches. The processor is configured to identify presently available combinations of the discrete loads and to select a preferred one of the presently available load combinations as function of control parameters and/or demand data provided to the processor.

In accordance with the invention there is provided a system, a controller and a non-transitory computer readable medium, as defined by the appended claims.

Certain embodiments of the present disclosure may provide one or more technical advantages. For example, allowing the system to operate in a first power outage mode allows the system to prevent the refrigerant in the tank from becoming over pressurized, thus reducing the risk of damage during a power outage. As another example, the first power outage mode allows the system to use its main equipment during a power outage mode, rather than having the system use an additional back up system and components. This solution reduces the number of additional parts required in the system, thus creating a simpler system that utilizes fewer resources and requires less routine maintenance for its back up components. One or more other technical advantages may be readily apparent to one skilled in the art from the figures, descriptions, and claims included herein.

For a more complete understanding of the present disclosure, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:.

Cooling systems may cycle a refrigerant to cool various spaces. For example, a refrigeration system may cycle refrigerant to cool spaces near or around refrigeration loads. In certain installations, such as at a grocery store for example, a refrigeration system may include different types of loads. For example, a grocery store may use medium temperature loads and low temperature loads. The medium temperature loads may be used for produce and the low temperature loads may be used for frozen foods. Refrigeration systems require a power supply in order to operate. In the case of a power outage, refrigerants (e.g., carbon dioxide) may start gaining heat such that the refrigerant pressure may rise and exceed the design pressure of the overall refrigeration system. The refrigeration system generally must be vented to the atmosphere in such a situation.

In order to avoid venting the refrigerant, refrigeration systems may include backup systems with additional motor drives (e.g., an extra set of compressors only used during a power outage) to keep the refrigerant cool and at a low pressure. Including any backup devices, however, may create a more complicated refrigeration system, requiring additional expenses for duplicate parts that are only used in power outages. These additional parts may require routine maintenance to ensure they are operable during a power outage. Thus, there is a desire for a simple refrigeration system that may operate during a power outage, while limiting the number of additional parts required.

Embodiments of the present disclosure and its advantages are best understood by referring to <FIG> of the drawings, like numerals being used for like and corresponding parts of the various drawings.

<FIG> is a block diagram illustrating example refrigeration system <NUM> according to some embodiments. Refrigeration system <NUM> includes utility power <NUM>, main distribution panel <NUM>, emergency electric power supply <NUM>, power switch <NUM>, controller <NUM>, motor drives <NUM>, a plurality of compressors <NUM>, and tank <NUM>.

During regular use, utility power <NUM> provides power to system <NUM>, allowing it to perform cooling and refrigeration. Main distribution panel <NUM> provides power from utility power <NUM> to any components of system <NUM> that require power to function, for example any of the motor drives <NUM> (e.g., compressors <NUM>). In some embodiments, main distribution panel <NUM> provides power directly to one or more motor drives <NUM>. In some embodiments, main distribution panel <NUM> may provide power through power switch <NUM> to one or more motor drives <NUM>. When there is a power outage, utility power <NUM> may be inaccessible such that system <NUM> may be limited on the refrigeration it can provide. Further, as discussed above, if no power is supplied to system <NUM>, refrigerants in tank <NUM> may start gaining heat such that the refrigerant pressure may rise and exceed the design pressure of the overall refrigeration system. In order to prevent any pressure building up in tank <NUM>, it may be beneficial to provide power to one or more of the compressors <NUM> to alleviate or limit any pressure build up in tank <NUM>. In general operation, system <NUM> comprises an emergency electric power supply <NUM> that may be used when utility power <NUM> is limited. Power switch <NUM> controls the power delivered to controller <NUM> and/or motor drives <NUM> from emergency electric power supply <NUM>. By providing power to components of system <NUM> that are regularly utilized and maintained, resources may be saved rather than used on additional components (e.g., backup compressors to be used during a power outage).

Emergency electric power supply <NUM> supplies power to refrigeration system <NUM> and is used if there is an issue with utility power <NUM>. For example, emergency electric power supply <NUM> may include one or more generators that are automatically switched on in the case of a power outage. Controller <NUM> determines the amount of power supplied by emergency electric power supply <NUM>. For example, controller <NUM> may have saved in its memory (e.g., memory <NUM> of <FIG>) the amount of power provided by emergency electric power supply). As additional examples, controller <NUM> may determine the wattage or voltage available, the total amount of power available (e.g., over what period of time the power may be supplied), and/or the number of generators available. For example, controller <NUM> may determine the amount of power available from one generator. However, if a user or operator requires additional support during the power outage, an additional generator may be brought in and/or turned on. That would allow controller <NUM> to determine the additional amount of power available, and provide additional compression to refrigerant and/or provide refrigeration during the power outage.

Power switch <NUM> routes power from emergency electric power supply <NUM> to controller <NUM> and motor drives <NUM>. Power switch <NUM> may be used when there is a power outage. Power switch <NUM> indicates or communicates to controller <NUM> (e.g., indicated by the dashed lines in <FIG>) that system <NUM> has experienced a power outage and that emergency electric power supply <NUM> should be used.

Motor drives <NUM> may include various components that interact with the refrigerant, including compressors <NUM>, gas cooler <NUM>, bypass valve <NUM>, and expansion valve <NUM>. Gas cooler <NUM> may cool the gas and lead the refrigerant to expansion valve <NUM>, which controls the flow of refrigerant and can reduce the pressure of refrigerant. Bypass valve <NUM> may be used to bypass gas cooler <NUM> when its benefits arc not needed for the refrigerant. Each of the motor drives <NUM> may receive signals or instructions from controller <NUM> to turn on, and uses the power delivered by power switch <NUM> from emergency electric power supply <NUM>, in order to turn on.

As discussed above, refrigeration system <NUM> includes a plurality of compressors <NUM>. Compressors <NUM> compress the refrigerant in tank <NUM> so that the system can recirculate the cooled, liquid refrigerant to keep the refrigeration load cool. Refrigeration system <NUM> may include any suitable number of compressors <NUM>. By including additional compressors, it reduces the amount of compression that other compressors need to apply to refrigerant. Compressors <NUM> may vary by design and/or by capacity. In some embodiments, there may be two groups of compressors <NUM>. For example, one group of compressors <NUM> may be powered directly by main distribution panel <NUM>, while a second group of compressors <NUM> may normally be powered by main distribution panel <NUM> through power switch <NUM>. This second group of compressors (e.g., those powered through power switch <NUM>) may be the group used during a power outage, because they can still receive power from emergency electric power supply <NUM> through power switch <NUM>, while the first group of compressors <NUM> may be unavailable because utility power <NUM> is experiencing issues. This design of having on compressor group powered through power switch <NUM> allows for compressors <NUM> to still be available for use during a power outage by being powered by emergency electric power supply <NUM>.

Tank <NUM> stores refrigerant used to cool an area around system <NUM>. This disclosure contemplates tank <NUM> storing refrigerant in any state such as, for example, a liquid state and/or a gaseous state. In some embodiments, the refrigerant may be carbon dioxide, which can increase the pressure on tank <NUM> if it is not kept cool. One or more compressors <NUM> compress the refrigerant such that it lessens the pressure in tank <NUM>.

Refrigeration system <NUM> includes at least one controller <NUM>. Controller <NUM> is configured to direct the operations of the refrigeration system. Controller <NUM> is communicatively coupled to components of the refrigeration system (i.e., motor drives <NUM>, compressors <NUM>, gas coolers <NUM>, bypass valve <NUM>, expansion valve <NUM>, and power switch <NUM>). As illustrated in <FIG>, the controller <NUM> is communicatively coupled to the various components of system <NUM>, as illustrated by the dashed lines. In some embodiments, the connections therebetween are through a wired-connection. A conventional cable and contacts may be used to couple the controller <NUM> to the various components of system <NUM> via the controller interface. In other embodiments, a wireless connection may also be employed to provide at least some of the connections.

Controller <NUM> is configured to control the operations of one or more components of refrigeration system <NUM>. Controller <NUM> is configured to turn compressors <NUM> on and off. Controller <NUM> is configured to determine when system <NUM> is using emergency electric power supply <NUM> and to determine an amount of power to supply to the first compressor based on the first power outage mode.

In some embodiments, controller <NUM> may further be configured to receive information about the refrigeration system from one or more sensors. As an example, controller <NUM> may receive information about the ambient temperature of the environment (e.g., outdoor temperature) from one or more sensors. As another example, controller <NUM> may receive information about the system load from sensors associated with compressors <NUM>. As yet another example, controller <NUM> may receive information about the temperature and/or pressure of the refrigerant from sensors positioned at any suitable point(s) in the refrigeration system.

As described above, controller <NUM> may be configured to provide instructions to one or more components of the refrigeration system. Controller <NUM> may be configured to provide instructions via any appropriate communications link (e.g., wired or wireless) or analog control signal. As depicted in <FIG>, controller <NUM> is configured to communicate with components of the refrigeration system. For example, in response to receiving an instruction from controller <NUM>, the refrigeration system may turn on one or more motor drives <NUM>, such as one or more compressors <NUM>. In some embodiments, controller <NUM> includes or is a computer system.

In operation, if system <NUM> suffers from a power outage, it may be desirable to supply a limited amount of power to system <NUM> such that it can prevent its components from damages and/or provide limited refrigeration. In operation, system <NUM> has a first power outage mode in which controller <NUM> uses power from emergency electric power supply <NUM> in order to run a sufficient number of compressors <NUM> such that the pressure of refrigerant in tank <NUM> remains at an acceptable level (e.g., there is no risk of over pressurizing tank <NUM>). System <NUM> also has a second power outage mode in which controller <NUM> uses power from emergency electric power supply <NUM> to run an additional number of compressors <NUM> and/or motor drives <NUM> such that system <NUM> may continue to deliver refrigeration. System <NUM> also includes a second power outage mode, which indicates to controller <NUM> what components should be turned on and for how long to ensure sufficient refrigeration. Having a second power outage mode that can supply refrigeration in a power outage may protect from overheating certain people, products, or components that system <NUM> is intended to cool. The operation of system <NUM> is described in further detail below with respect to <FIG> and <FIG>.

This disclosure recognizes that a refrigeration system, such as system <NUM> depicted in <FIG>, may comprise one or more other components. As an example, the refrigeration system may comprise one or more condensers or humidity sensors in some embodiments. Some systems may include a booster system with ejectors and parallel compression. One of ordinary skill in the art will appreciate that the refrigeration system may include other components not mentioned herein.

<FIG> is a flowchart illustrating method <NUM> of operating the example refrigeration system <NUM> of <FIG>. Various components of system <NUM> perform the steps and method <NUM>.

The method may begin at step <NUM>. At step <NUM>, controller <NUM> determines whether system <NUM> is using emergency electric power supply <NUM>. Controller <NUM> receives an indication from power switch <NUM> that system <NUM> is using emergency electric power supply <NUM>. When a power outage occurs, a separate system may automatically turn on emergency electric power supply <NUM>, which may automatically activate power switch <NUM> as well. Because power switch <NUM> and controller <NUM> are communicatively coupled, controller <NUM> recognizes that power switch <NUM> is being utilized and determines that system <NUM> has incurred a power outage, and thus it is using emergency electric power supply <NUM> to operate. Emergency electric power supply <NUM> allows system <NUM> to operate in a limited manner, for example, to prevent tank <NUM> from becoming over pressurized.

At step <NUM>, controller <NUM> operates system <NUM> in a first power outage mode to control the power supplied to system <NUM> when system <NUM> experiences a power outage. System <NUM> may supply just enough power such that one or more compressors <NUM> may compress the refrigerant in tank <NUM> such that it keeps the pressure under control. For example, first power outage mode may allow one compressor <NUM> to turn on and compress refrigerant in tank. This amount of compression may keep the pressure in tank <NUM> at a normal level until utility power <NUM> is revived. First power outage mode may control which of the multiple compressors <NUM> are turned on, the length of time they are turned on for, and whether the compressors are sequenced (e.g., one is turned on for a period of time, then another is turned on for another period of time while the first one is turned off). First power outage mode is used when refrigeration is not required during a power outage, and the primary concern includes keeping the refrigerant in tank <NUM> at an appropriate amount of pressure.

At step <NUM>, controller <NUM> determines an amount of power to supply the first compressor (e.g., compressor <NUM>) based on the first power outage mode. In the example used above, if first power outage mode requires one compressor (e.g., one of compressors <NUM>) to be turned on, controller <NUM> may determine the amount of power to supply for one compressor to operate. By determining the amount of power required, controller <NUM> may compare to the amount of power available to ensure that compressor <NUM> may be safely and adequately operated during the power outage. In some embodiments, controller <NUM> may determine that the power available from emergency electric power supply <NUM> is not a sufficient amount to power one or more compressors <NUM> as dictated by the first power outage mode. When this occurs, controller <NUM> may send a signal to indicate, for example to an operator or user, that there is an insufficient power supply and the tank <NUM> may suffer from a large amount of pressure. In some embodiments, controller <NUM> may omit this step because system <NUM> is designed to have sufficient power to turn on compressor <NUM>, and thus controller <NUM> may immediately turn on compressor <NUM>, as described below at step <NUM>.

At step <NUM>, controller <NUM> transmits a signal to instruct compressor <NUM> to turn on. Controller <NUM> may transmit the signal either through a wired or wireless communication. By turning on compressor <NUM>, controller <NUM> ensures that it will compress refrigerant in tank <NUM> and maintain an adequate pressure. Controller <NUM> may transmit a signal to more than one compressor <NUM>. In some embodiments, controller <NUM> may further turn on other motor drives <NUM> to ensure compressor <NUM> may adequately maintain the refrigerant in tank <NUM>.

At step <NUM>, controller <NUM> transmits an indication for display that system <NUM> is in the first power outage mode. The indication that system <NUM> is in the first power outage mode may be displayed on an interface such that a user, operator, or maintenance person may be able to tell what mode. This may be useful for the user to know that, although there is a power outage, system <NUM> is operating safely and ensuring the pressure in tank <NUM> is at an adequate level. The user may input the specific mode the user would like system <NUM> to operate at. For example, system <NUM> may not switch to first power outage mode without an indication from the user through the interface and/or display. A user may instruct system <NUM> to operate in a different mode, as explained below. After transmitting an indication for display that system <NUM> is in the first power outage mode, the method ends.

Modifications, additions, or omissions may be made to method <NUM> depicted in <FIG>. Method <NUM> may include more, fewer, or other steps. For example, steps may be performed in parallel or in any suitable order, and steps may be omitted. While discussed as various components of refrigeration system <NUM> performing the steps, any suitable component or combination of components of system <NUM> may perform one or more steps of the method.

At step <NUM>, controller <NUM> determines whether the system is using emergency electric power supply <NUM>. For example, a power outage may render utility power <NUM> unusable, and thus system <NUM> has automatically switched to using backup power and/or generators in emergency electric power supply <NUM>. One or more aspects of step <NUM> may be implemented using one or more techniques discussed above with respect to step <NUM> of method <NUM> illustrated in <FIG>. If controller <NUM> determines that system <NUM> is using emergency electric power supply <NUM>, it can determine to operate a second power outage mode, wherein system <NUM> provides refrigeration (rather than first power outage mode described in <FIG>) in two different ways. First, controller <NUM> may determine to operate in second power outage mode if it receives an instruction to do so (as explained in step <NUM> below). Second, controller <NUM> may determine to operate in second power outage mode if it determines there is a sufficient amount of power available from emergency electric power supply <NUM> (as explained in step <NUM> below).

At step <NUM>, controller <NUM> determines whether it has received an instruction to operate in a second power outage mode. Controller <NUM> may receive this instruction from a user's interaction with an interface (e.g., wall display, computer, and/or mobile device). The user may interact with a display to select the second power outage mode (e.g., override the system's automatic selection of the first power outage mode. Second power outage mode allows for system <NUM> to provide cooling or refrigeration, rather than simply maintain the pressure in tank <NUM> as in first power outage mode. For example, a user may own a grocery store and notice that there is a power outage. Because the meat section of his grocery store contains very valuable selections that the user does not wish to spoil during the power outage, the user may choose to provide a limited amount of refrigeration during the power outage. Continuing the example, the user may bring in or already have an additional backup power supply to help provide refrigeration, and then select the second power outage mode. The second power outage mode may provide instructions to controller <NUM> on the amount of refrigeration to provide (e.g., low load, medium load, and/or high load), and certain areas of a store or building to provide the cooling to (e.g., meat section of a grocery store, server room of an office).

At step <NUM>, controller <NUM> determines whether a second compressor (e.g., one of compressors <NUM>) may be turned on based on the second power outage mode. Controller may access set requirements for the second power outage mode, for example in memory <NUM> of <FIG>, to determine what components may be turned on based on that mode. If controller <NUM> determines that second compressor <NUM> may be turned on, the method continues to step <NUM> where the second compressor <NUM> is turned on, as discussed below. If controller <NUM> determines that the second compressor <NUM> may not be turned on based on the second power outage mode, the method continues to step <NUM>.

At step <NUM>, controller <NUM> determines an amount of power available from emergency electric power supply <NUM>. Controller <NUM> may determine this information using variables and logic stored in its memory <NUM> (e.g., memory may indicate an amount of power available during a power outage). Controller <NUM> determines the power available (e.g., wattage, voltage) for a period of time and/or the number of generators available. For example, controller <NUM> may know (e.g., stored in memory <NUM>) the amount of power available from one generator, and using the number of generators available, then determine the total amount of power available from emergency electric power supply <NUM>.

At step <NUM>, controller <NUM> determines a second power outage mode based on the amount of power available. The second power outage mode may indicate and control what components may be turned on (e.g., compressors <NUM>, gas cooler <NUM>) while operating in this mode, and for how long. At step <NUM>, controller <NUM> determines whether second compressor <NUM> can be turned on based on the second power outage mode. if controller <NUM> determines a second compressor <NUM> cannot be turned on, then the method ends. If controller <NUM> determines second compressor <NUM> can be turned on, the method continues to step <NUM>. At step <NUM>, controller <NUM> transmits a signal to instruct second compressor <NUM> to turn on. One or more aspects of step <NUM> may be implemented using one or more techniques discussed above with respect to step <NUM> of method <NUM> illustrated in <FIG>.

At step <NUM>, controller <NUM> determines whether a third compressor <NUM> can be turned on based on the second power outage mode. Controller <NUM> may look at the settings for the second power outage mode (e.g., settings stored in memory <NUM> of controller <NUM>) and determine how many compressors <NUM> may be used. Second power outage mode may also indicate the load needed to supply limited refrigeration, and thus controller <NUM> may determine the number of compressors <NUM> required to be in use in order to supply that necessary load. One or more aspects of step <NUM> may be implemented using one or more techniques discussed above with respect to step <NUM>. If controller <NUM> determines that third compressor <NUM> cannot be turned on, the method ends. If controller <NUM> determines that third compressor <NUM> can be turned on, the method continues to step <NUM> and controller <NUM> transmits a signal to instruct the third compressor to turn on. One or more aspects of step <NUM> may be implemented using one or more techniques discussed above with respect to step <NUM>.

Steps <NUM>-<NUM> in general determine whether other motor drives <NUM> may be turned on based on the amount of power available. For example, some of these motor drives may not be necessary to provide a limited amount of cooling during a power outage, however, it may be beneficial to turn them on if there is power available. The amount of power required to operate these motor drives <NUM> may be so low, that controller <NUM> determines they should be turned on regardless of the power supply. In some embodiments, controller generally determines whether there is sufficient power, and if so, turns on one or more motor drive components. These steps are described in more detail below.

At step <NUM>, controller <NUM> determines the amount of power available from emergency electric power supply <NUM>. Controller <NUM> may determine the amount that is not currently in use, for example, the amount not being used by a first, second, and/or third compressor <NUM> that may have already been switched on. One or more aspects of step <NUM> may be implemented using one or more techniques discussed above with respect to step <NUM>. At step <NUM>, controller <NUM> determines whether the power calculated in step <NUM> is sufficient to turn on gas cooler <NUM>. Controller <NUM> may determine the total amount of power required to keep gas cooler <NUM> operating for a certain period of time. If controller <NUM> determines there is insufficient power, the method ends. If controller <NUM> determines there is enough power, then at step <NUM>, controller <NUM> transmits a signal to instruct gas cooler <NUM> to turn on. One or more aspects of step <NUM> may be implemented using one or more techniques discussed above with respect to steps <NUM> and <NUM>.

At step <NUM>, controller <NUM> determines whether there is sufficient power to turn on expansion valve <NUM>. Controller <NUM> may recalculate the remaining power, for example, if it turned on gas cooler <NUM> in step <NUM> and thus the power supply available is lower than the amount previously determined at step <NUM>. One or more aspects of step <NUM> may be implemented using one or more techniques discussed above with respect to step <NUM>. If controller <NUM> determines there is sufficient power at step <NUM>, then at step <NUM>, controller <NUM> transmits a signal to instruct expansion valve <NUM> to turn on. One or more aspects of step <NUM> may be implemented using one or more techniques discussed above with respect to steps <NUM>, <NUM>, and <NUM>.

At step <NUM>, controller <NUM> determines whether there is sufficient power to turn on bypass valve <NUM>. One or more aspects of step <NUM> may be implemented using one or more techniques discussed above with respect to steps <NUM> and <NUM>. If controller <NUM> determines there is sufficient power, then at step <NUM>, controller <NUM> transmits a signal to instruct bypass valve to turn on. One or more aspects of step <NUM> may be implemented using one or more techniques discussed above with respect to steps <NUM>, <NUM>, <NUM>, and <NUM>. Then the method ends.

Modifications, additions, or omissions may be made to method <NUM> depicted in <FIG>. Method <NUM> may include more, fewer, or other steps. For example, steps may be performed in parallel or in any suitable order, and steps may be omitted. While discussed as various components of cooling system <NUM> performing the steps, any suitable component or combination of components of system <NUM> may perform one or more steps of the method.

<FIG> illustrates an example controller <NUM> for a refrigeration system, such as controller <NUM> of <FIG>. Controller <NUM> may comprise one or more interfaces <NUM>, memory <NUM>, and one or more processors <NUM>. Interface <NUM> receives input (e.g., sensor data or system data), sends output (e.g., instructions), processes the input and/or output, and/or performs other suitable operation. Interface <NUM> may comprise hardware and/or software. As an example, interface <NUM> receives information from sensors, such as information about the ambient temperature of refrigeration system, information about the load of the refrigeration system, information about the temperature of the refrigerant at any suitable point(s) in the refrigeration system, and/or information about the pressure of the refrigerant at any suitable point(s) in the refrigeration system (e.g., pressure of tank <NUM>). Controller <NUM> determines whether system <NUM> of <FIG> is using emergency electric power supply <NUM>, for example, due to a power outage. In some embodiments, controller <NUM> sends instructions to the component(s) of the refrigeration system that controller <NUM> has may want to power on and/or adjust (e.g., compressor(s) <NUM>, gas cooler <NUM>, bypass valve <NUM>, expansion valve <NUM>, etc.).

Processor <NUM> may include any suitable combination of hardware and software implemented in one or more modules to execute instructions and manipulate data to perform some or all of the described functions of controller <NUM>. Processor <NUM> may include, for example, one or more computers, one or more central processing units (CPUs), one or more microprocessors, one or more applications, one or more application specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), and/or other logic.

Memory (or memory unit) <NUM> stores information. As an example, memory <NUM> may store information about different power outage modes, specifically the settings to apply to one or more motor drives <NUM> (e.g., to compressor(s) <NUM>) during a power outage. Memory <NUM> may comprise one or more non-transitory, tangible, computer-readable, and/or computer-executable storage media. Examples of memory <NUM> include computer memory (for example, Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (for example, a hard disk),removable storage media (for example, a Compact Disk (CD) or a Digital Video Disk (DVD)), database and/or network storage (for example, a server), and/or other computer-readable medium.

Modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein without departing from the scope of the invention, which is defined by the appended claims. The components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses may be performed by more, fewer, or other components. For example, the refrigeration system may include any suitable number of compressors <NUM>, gas coolers <NUM>, bypass valves, <NUM>, expansion valves <NUM>, tanks <NUM>, controllers <NUM>, power switches <NUM>, and emergency electric power supplies <NUM>, and so on, as performance demands dictate. One skilled in the art will also understand that refrigeration system <NUM> can include other components that are not illustrated but are typically included with refrigeration systems. Additionally, operations of the systems and apparatuses may be performed using any suitable logic comprising software, hardware, and/or other logic. As used in this document, "each" refers to each member of a set or each member of a subset of a set.

Claim 1:
A system (<NUM>), comprising:
an emergency electric power supply (<NUM>) configured to supply power to at least one motor drive of the system (<NUM>);
a power switch (<NUM>) coupled to the emergency electric power supply (<NUM>);
a tank (<NUM>) configured to store a refrigerant;
first and second compressors (<NUM>) configured to compress the refrigerant in the tank (<NUM>);
a controller (<NUM>) according to claim <NUM> coupled to the power switch (<NUM>) and the first and second compressors (<NUM>).