Load management for refrigerated truck units

Abstract

A system for managing power in a transport refrigeration unit (TRU) mounted on a trailer is disclosed, comprising: a TRU controller configured to execute a range extender operating mode to manage the operation of the TRU and TRU components, wherein the TRU controller: selects a power management strategy from a plurality of demand-side power management strategies; determines operating parameters of the TRU from the selected power management strategy; and executes the generated operating parameters.

Description

Background Art

[0001] The exemplary embodiments relate to the field of power management, and more particularly to power management in transport refrigeration units.

[0002] Refrigerated trailers may include a transport refrigeration unit (TRU) to provide appropriate conditioning for the cargo shipped in the trailer. Large diesel TRU engines can be replaced with efficient small engines in hybrid system architectures or removed in all-electric designs. Therefore, multiple supplemental power sources in hybrid or engine-less TRUs should be managed to achieve design benefits. In addition to managing supplied energy, demand-side power consumption can be intelligently controlled to extend the service range of the integrated cooling system while maintaining cargo reliability.

[0003] For example, a battery powered TRU may have an onboard rechargeable energy storage system (battery) that may be charged by direct connection to a power main. Such a power main may include the Eastern Interconnection Grid (which is part of the continental United States transmission grid) and any grid source, or distributed generation source from a customer's location or delivery location. The power main may be alternating current (AC) at, for example, 50 Hz or 60 Hz, or the power may be direct current (DC) from a dispatchable or non-dispatchable source, such as an on-site solar grid or a solar grid on the roof of a trailer housing the TRU. The TRU may also perform a power take-off process from the main vehicle engine or from kinetic energy recovered from the vehicle. Summary of the invention

[0004] A system for managing power in a transport refrigeration unit (TRU) mounted on a trailer is disclosed, comprising: a TRU controller configured to execute a range extender operating mode to manage the operation of the TRU and TRU components, wherein the TRU controller: selects a power management strategy from a plurality of demand-side power management strategies; determines operating parameters of the TRU from the selected power management strategy; and executes the generated operating parameters.

[0005] Additionally or alternatively to one or more of the features disclosed above, the TRU components include a TRU power supply component and a TRU power demand component.

[0006] Additionally or alternatively to one or more of the features disclosed above, the TRU power supply components include one or more of a TRU battery and a TRU engine, and the TRU power demand components include one or more of a compressor, an evaporator, a condenser, cargo lights, and a TRU controller.

[0007] In addition or alternatively to one or more of the features disclosed above, the plurality of power management strategies include: a first strategy for utilizing cargo thermal storage as a flexible power load, a second strategy for reducing a thermal energy transfer rate, and a third strategy for flexibly performing non-critical diagnostics and non-critical TRU system functions.

[0008] Additionally or alternatively to one or more of the features disclosed above, the first strategy includes: the TRU controller determining a first strategy condition for pre-cooling cargo at predetermined geographic mission locations where energy is available, and reducing cooling set points between the predetermined mission locations.

[0009] In addition or alternatively to one or more of the features disclosed above, the TRU controller: determines cargo thermal storage capacity by direct monitoring using thermal sensors or by inference from operational data; identifies the locations of and transit times between the predetermined geographic mission locations based on dynamically updated GPS data and full mission proximity to grid charging stations; and adjusts TRU power demand for cooling between the predetermined mission locations by applying power load sharing strategies and power removal, reduction and / or peak limiting strategies.

[0010] In addition to or alternatively to one or more of the features disclosed above, the TRU controller implements the first strategy condition and performs one or more of the following: (i) adapting the cooling set point for the cargo within a predetermined range; and (ii) modifying the evaporator fan speed and / or the condenser fan speed and / or the compressor speed.

[0011] In addition or alternatively to one or more of the features disclosed above, the second strategy includes: the TRU controller performs one or more of the following: (i) limiting the opening of the refrigeration cycle cooling valve, the refrigeration cycle cooling valve including one or more of the expansion valve and the suction regulating valve, and (ii) modifying the TRU fan speed and / or the TRU compressor speed.

[0012] In addition to or in lieu of one or more of the features disclosed above, the third strategy includes: the TRU controller performing one or more of the following: (i) performing one or more non-critical diagnostic functions before a predetermined schedule, or postponing performance of the one or more non-critical diagnostic functions until a predetermined geographic mission location is reached where energy is available, (ii) performing a defrost cycle based on a non-periodic triggering event, and (iii) removing, reducing and / or peak limiting non-critical power loads.

[0013] Additionally or alternatively to one or more of the features disclosed above, the TRU controller executes the range extender operating mode prior to and periodically during a mission.

[0014] Further disclosed is a method for managing power in a trailer mounted transport refrigeration unit (TRU) comprising one or more of the features disclosed above. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The following description should not be considered limiting in any way. Referring to the accompanying drawings, like elements are numbered the same:

[0016] Figure 1 is a diagrammatic representation of components according to an embodiment;

[0017] Figure 2 is a flow chart according to the implementation plan;

[0018] Figure 3 is a flow chart according to the implementation plan;

[0019] Figure 4 is a flow chart according to the implementation plan;

[0020] Figure 5 is a flow chart according to an implementation scheme; and

[0021] Figure 6 It is a flow chart according to the implementation scheme. DETAILED DESCRIPTION

[0022] A detailed description of one or more embodiments of the disclosed apparatus and methods is given herein by way of example and not limitation with reference to the accompanying drawings.

[0023] Go to Figure 1 , the operating environment of the embodiment may include a trailer 100 having a transport refrigeration unit (TRU) 104 therein. The trailer may be towed by a tractor 90 having a plurality of power supply components. The plurality of trailer power supply components may include one or more of a motor 92, a battery 94, and a power regeneration axle 96. In addition, the trailer may have a power controller 98 for controlling the plurality of trailer power supply components.

[0024] The TRU may include a plurality of TRU components, including a plurality of TRU power supply components and a plurality of power demand components. The TRU power supply components may include a TRU engine 108 and a TRU battery 112. The plurality of TRU power demand components may include a compressor 116, which may be a variable displacement compressor. The TRU power demand components may further include an evaporator / condenser 120 with an associated fan 124. In addition, the power demand components may include cargo lights 128.

[0025] The plurality of TRU components may be dynamically controlled by a TRU electronic controller 132. The TRU controller may be carried on the TRU engine, or may be a separate component in the TRU. The TRU controller may be able to communicate with the trailer TRU power controller to control the use and distribution of power from the trailer power supply components.

[0026] The TRU controller may be equipped with a service that provides dynamically updated global positioning system (GPS) data 136. Through GPS, the TRU controller may be able to identify the best route, distance to a service station 138, etc. It should be understood that for an electric TRU, the service station 138 will be connected to the power grid. The TRU controller may include a visual interface 140. It should be understood that the TRU controller is also an electrical power consumer. The TRU controller may control a plurality of cooling valves, including an expansion valve 144 and a suction regulating valve 148.

[0027] In addition, the TRU controller may communicate with cargo sensors 152 disposed in cargo storage areas 156. The cargo sensors may be, for example, thermal sensors. The TRU controller may communicate with and be programmed by a central server 160, which may be a fleet central server that manages a fleet of such trailers. Such communication may occur over a cellular or other wireless network 164 or a wired network arranged at a fleet headquarters 168. Communication may also occur with one or more cellular devices 170 owned by a vehicle operator or maintenance personnel for diagnostic or other operational purposes.

[0028] Go to Figure 2 In one embodiment, the TRU controller can manage demand-side energy requirements to extend the TRU operating range. The purpose of this process is to adaptively manage power requirements based on power availability, including when power is available and how much power is available. This process can be initiated automatically by the TRU controller. Optionally, this process can be initiated in response to dynamic communication between the TRU controller and the fleet central server. Optionally again, this process can be initiated by the trailer operator through an on-board visual interface or by directly interacting with the TRU controller using a mobile device. This decision process can include current and future forecasts of energy available from dispatchable or non-dispatchable (such as solar) sources.

[0029] When managing the energy requirements of the TRU, the TRU controller may perform step S100: executing the range extender operation mode to manage TRU operation and power consumption. In the range extender mode, the TRU configures a flexible TRU energy consumption management strategy by, for example, predicting the thermal load and details required to deliver the mission.

[0030] In step S104, the TRU controller performs the steps of selecting a power management strategy. In step S108, the TRU controller determines whether to utilize cargo thermal storage as a flexible load for the power management strategy, which will be discussed in detail below. In step S112, the TRU controller determines whether to reduce the thermal energy transfer rate for the power management strategy, which will be discussed in detail below. In step S116, the TRU controller determines whether to flexibly perform non-critical diagnostics and other functions for the power management strategy, which will be discussed in detail below. The order of performing steps S108, S112 and 116 shown is not limiting. In step S118, the TRU controller determines whether step S104 should be revisited or whether this portion of the process is complete.

[0031] If the determination at step S118 is "yes", the TRU controller performs step S120: determines whether step S100 is being performed during the transport mission, and whether the newly determined parameters are different from the currently performed parameters. If the determination at S120 is "yes", the controller performs step S124: modifies the performed operating parameters of the TRU to provide improved load management for the remainder of the mission. If the determination at step S120 is "no", no parameter changes are performed.

[0032] Go to Figure 1 , Figure 2 and Figure 3 , if the TRU controller selects "yes" at step S108, the TRU controller may perform step S140: determining a first policy condition for pre-cooling the cargo at predetermined geographic mission locations where cheap and clean energy is available, and reducing cooling set points between predetermined mission locations. In step S144, the TRU controller may determine the cargo thermal storage capacity by direct monitoring using thermal sensors or by inference from operational data. Cargo thermal storage refers to how much heat or cold the cargo can store, and this can be determined by the amount and rate at which the cargo loses stored energy. In the absence of cargo sensors (including, for example, cargo space air temperature sensors), this can be inferred from the dynamics of the temperature in the storage area (e.g., rise time).

[0033] In step S148, the TRU controller can identify the locations of scheduled mission locations where cheap and clean energy is available and the transportation time between them based on dynamically updated GPS data and full mission proximity to grid charging stations. In step S152, the TRU controller can determine the TRU power available for cooling between the scheduled mission locations by applying power load sharing strategies and power removal, reduction and / or peak limiting strategies. By modifying operating parameters, such as changing actuator speeds and cooling set points, adjust how much power the refrigeration unit will need (demand).

[0034] In step S172, the TRU controller may implement a first strategy based on steps S140 to S152. That is, the TRU controller may precool the cargo or reduce cooling until, for example, grid power is available. For any of these options, the TRU controller may perform step S176: selecting TRU parameters to adjust. In step S180, the TRU controller may choose to adapt the cooling set point for the cargo within an acceptable range to precool or reduce cooling based on the position in the mission. In step S182, the TRU controller may choose to modify the evaporator and / or condenser fan speeds and compressor speeds to precool or reduce cooling based on the position in the mission.

[0035] A "yes" response at step S180 may cause the TRU controller to perform step S184: adapting the cooling set point, while a "yes" response at step S182 may cause the TRU controller to perform step S186: changing the fan speed and / or compressor speed. The order shown for performing steps S180 and S182 is not limiting, and upon performing either of these steps, the TRU controller returns to step S176. At step S188, the TRU controller may determine whether step S176 should be revisited or whether this portion of the process is complete. A "yes" determination at step S188 may proceed with the TRU controller returning to step S104.

[0036] Go to Figure 1 , Figure 2 and Figure 4 , if the TRU controller selects "yes" at step S112, the TRU controller may perform step S200 of selecting TRU parameters to adjust. At step S204, the TRU controller may choose to limit the opening of refrigeration cycle cooling valves (such as expansion valves and suction regulating valves). At step S208, the TRU controller may choose to modify the evaporator / condenser fan speed and / or compressor speed. A "yes" response at step S204 may cause the TRU controller to perform step S212 of adjusting the valves. A "yes" response at step S208 may cause the TRU controller to perform step S216 of adjusting the fan speed and / or compressor speed. The order of performing steps S204 and S208 shown is not limiting, and when performing any of these steps, the TRU controller returns to step S200. At step S218, the TRU controller determines whether step S220 should be revisited or whether this portion of the process is complete. A "yes" determination at step S218 continues and the TRU controller returns to step S104.

[0037] Go to Figure 1 , Figure 2 and Figure 5, if the TRU controller selects "yes" at step S116, the TRU controller may execute step S220 of selecting TRU parameters for adjustment. Given the state of TRU power availability, the TRU controller may execute step S224: performing one or more non-critical diagnostic functions prior to a predetermined schedule. In the same step, the TRU controller may choose to postpone the execution of such non-critical diagnostic functions until a predetermined geographic mission location, i.e., a service station or a mission final destination, where energy is available is reached. In step S228, the TRU controller may determine whether to perform a defrost cycle based on a non-periodic trigger event rather than a periodic manner. In step S232, the TRU controller may determine whether to remove / reduce / peak power limit or adapt non-critical loads, such as dimming and TRU controller display functions.

[0038] A "yes" response at step S244 may cause the TRU controller to execute step S236: perform diagnostics as determined, prior to a predetermined schedule or at a delayed time. A "yes" response at step S228 may cause the TRU controller to execute step S240: monitor for a non-periodic triggering event before performing a defrost cycle. A "yes" response at step S232 may cause the TRU controller to execute step S244: remove, reduce and / or peak limit the electrical load as determined. The order shown for executing steps S236, S240 and S244 is not limiting, and upon executing any of these steps, the TRU controller returns to step S220. In step S248, the TRU controller determines whether step S220 should be revisited or whether this portion of the process is complete. A "yes" determination at step S248 continues and the TRU controller returns to step S104.

[0039] The process disclosed above can provide the ability to flexibly adjust load power consumption according to available power and make TRU operation more resilient and more robust to failures. This process can maintain the quality of transported goods during energy limited conditions.

[0040] Now go to Figure 1 and Figure 6 , instead of or in addition to executing Figures 2 to 5 , in attempting to manage the power system in the trailer, the TRU controller may perform step S260: executing a first program 180 that functions as a system-level energy manager.

[0041] By executing the first procedure, the TRU controller may perform step S264: adaptively select energy flow parameters based on one or more mission-specific parameters and TRU power health (such as battery state of charge and battery health). The mission-specific parameters may include one or more of the following: actual and predicted weather and traffic conditions within the route, driver preferences, proximity to grid charging stations within the route, type of cargo loaded, required temperature set point and airflow for cargo, current temperature of cargo, and refrigeration cycle efficiency. For example, the type of cargo loaded may be perishable or non-perishable, the required temperature set point for cargo is below or above the freezing temperature of the loaded cargo, and the driver preferences define the minimum duration between connections to grid charging stations. The TRU power health includes the observed status and full mission expected status of the TRU power supply components and power demand components. The refrigeration cycle efficiency may be learned from recorded trend / historical data related to the TRU operating mode, outside air temperature, altitude, and cooling / heating loads. As a result of executing the first procedure, the TRU controller may make an overall decision on how to better coordinate the operation of the TRU with the installed power options to meet the (multiple) goals of the delivery mission.

[0042] In one embodiment, by executing the first program, the TRU controller may perform step S272: execute the first module 184, the first module 184 being a predictive analysis module. By executing the first module, the TRU controller may perform step S276: collect a first information data set 188, the information being task-specific information. Using the collected information data set, the TRU controller may perform step S280: predict the cooling power demand of the TRU.

[0043] In one embodiment, by executing the first program, the TRU controller may execute step S284: execute the second module 192, which is an online optimization module. By executing the second module, the TRU controller may execute step S288: generate a power schedule for the TRU based on the power demand for the specific load determined in step S280.

[0044] In addition, by executing the second module, the TRU controller may perform step S288: coordinate battery usage with the tractor power controller. By executing step S288, the TRU controller may perform step S292: collect a second information data set. The second information data set may include mission-specific information of the tractor, the mission-specific information including a predicted vehicle speed cycle. Using the first data set information and the second data set information, the TRU controller may perform step S292: determine the availability of power output directly from the tractor engine or through a regenerative axle on the tractor.

[0045] At step S296, the TRU controller may determine whether to re-execute the system-level energy manager during the task. This step may include the TRU executing step S300: determining whether to adjust the predetermined time interval based on the updated task-specific conditions and the TRU power health status. If the determination at step S300 is "yes", the TRU controller may execute step S304: adjust the time period between executions of the system-level energy manager. After adjusting the time at step S304, or if the determination at step S300 is "no", the TRU controller may execute step S308: determine whether the currently set time interval has passed. If the determination at step S308 is "no", the TRU controller may loop back to step S296. If the determination at step S308 is "yes", the TRU controller may loop back to step S260.

[0046] Using holistic information about the system's current and predicted behavior to proactively manage power flows and battery operation can enable uninterrupted operation of the TRU while improving the efficiency of the integrated system. This approach can also (i) enable the prioritization of clean energy for operation in urban areas with stricter emissions and noise regulations, (ii) minimize fuel consumption and emissions for systems equipped with range extenders (i.e., with reduced-size engines) to ensure that the TRU is operated only when absolutely necessary, and (iii) minimize operating costs, for example, by optimizing grid charging during peak hours with respect to fuel costs.

[0047] The term "about" is intended to include the degree of error associated with the measurement of a specific amount based on the available equipment when submitting the application. The terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "a", "an" and "said" are intended to also include plural forms, unless the context clearly indicates otherwise. It should be further understood that the term "comprising" used in the specification specifies the presence of the features, wholes, steps, operations, elements and / or parts, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, parts and / or combinations thereof.

[0048] Although the present disclosure has been described with reference to one or more exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and elements thereof may be replaced with equivalents without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt specific situations or materials to the teachings of the present disclosure without departing from the substantive scope of the present disclosure. Therefore, it is intended that the present disclosure is not limited to the specific embodiments disclosed as the best mode for implementing the present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.

Claims

1. A system for managing power in a transport refrigeration unit (TRU) mounted on a trailer for cooling cargo in the trailer, comprising: A TRU controller configured to execute a power management mode to manage operations of the TRU and TRU components, wherein the TRU controller: selecting a power management strategy from a plurality of demand-side power management strategies; as well as executing the selected power management strategy; The multiple demand-side power management strategies include: A first strategy utilizing cargo thermal storage as an electrical load, the first strategy comprising the TRU controller determining, either by direct monitoring with thermal sensors or by inference from operational data, an amount of cooling energy that can be stored by the cargo in the trailer and a rate at which the cargo in the trailer loses the stored energy and thereafter: (i) determining a first strategic condition for pre-cooling the cargo at a predetermined geographic mission location where energy is available; and (ii) reducing cooling set points between the predetermined geographic mission locations.

2. The system of claim 1, wherein the TRU components include a TRU power supply component and a TRU power demand component.

3. The system of claim 2, wherein the TRU power supply components include one or more of a TRU battery and a TRU engine, and the TRU power demand components include one or more of a compressor, an evaporator, a condenser, cargo lights, and the TRU controller.

4. The system of claim 3, wherein the plurality of demand-side power management strategies include: a second strategy to reduce the rate of thermal energy transfer, and a third strategy to flexibly perform diagnostic functions and TRU system functions.

5. The system of claim 1 , wherein the TRU controller: identifies the locations of and transportation times between the predetermined geographic mission locations based on dynamically updated GPS data and full mission proximity to grid charging stations; and adjusts TRU power demand for cooling between the predetermined geographic mission locations by applying one or more of a power load sharing strategy, a power removal strategy, a power reduction strategy, and a peak limiting strategy.

6. The system of claim 5, wherein the TRU controller implements the first strategy condition and performs one or more of: (i) adapting a cooling set point for the cargo within a predetermined range; and (ii) modifying an evaporator fan speed and / or a condenser fan speed and / or a compressor speed.

7. The system of claim 4, wherein the second strategy comprises: The TRU controller performs one or more of: (i) limiting the opening of refrigeration cycle cooling valves, including one or more of an expansion valve and a suction modulating valve, and (ii) modifying a TRU fan speed and / or a TRU compressor speed.

8. The system of claim 4, wherein the third strategy comprises: The TRU controller performs one or more of the following: (i) performing one or more diagnostic functions in advance of a predetermined schedule, or deferring performance of the one or more diagnostic functions until a predetermined geographic mission location is reached where energy is available, (ii) performing a defrost cycle based on a non-periodic triggering event, and (iii) removing, reducing and / or peak limiting electrical loads.

9. The system of claim 4, wherein the TRU controller executes the power management mode prior to a task and periodically during a task.

10. A method for managing power in a transport refrigeration unit (TRU) mounted on a trailer for cooling cargo in the trailer, comprising: A TRU controller configured to execute a power management mode to manage operations of the TRU and TRU components, wherein the TRU controller: selecting a power management strategy from a plurality of demand-side power management strategies; as well as executing the selected power management strategy; wherein the plurality of demand-side power management strategies include: a first strategy utilizing cargo thermal storage as a power load, the first strategy comprising the TRU controller: determining, by direct monitoring using thermal sensors or by inference from operational data, an amount of cooling energy that can be stored by the cargo in the trailer and a rate at which the cargo in the trailer loses the stored energy and thereafter: (i) determining a first strategic condition for pre-cooling the cargo at a predetermined geographic mission location where energy is available; and (ii) reducing cooling set points between the predetermined geographic mission locations.

11. The method of claim 10, wherein the TRU components include a TRU power supply component and a TRU power demand component.

12. The method of claim 11, wherein the TRU power supply components include one or more of a TRU battery and a TRU engine, and the TRU power demand components include one or more of a compressor, an evaporator, a condenser, cargo lights, and the TRU controller.

13. The method of claim 12, wherein the plurality of demand-side power management strategies include: a second strategy to reduce the rate of thermal energy transfer, and a third strategy to flexibly perform diagnostic functions and TRU system functions.

14. The method of claim 10, wherein the TRU controller: identifies the locations of the predetermined geographic mission locations and the transportation times therebetween based on dynamically updated GPS data and full mission proximity to grid charging stations; and adjusts the TRU power demand for cooling between the predetermined geographic mission locations by applying one or more of a power load sharing strategy, a power removal strategy, a power reduction strategy, and a peak limiting strategy.

15. The method of claim 14, wherein the TRU controller implements the first strategy condition and performs one or more of: (i) adapting a cooling set point for the cargo within a predetermined range; and (ii) modifying an evaporator / condenser fan speed and / or a compressor speed.

16. The method of claim 13, wherein the second strategy comprises: The TRU controller performs one or more of: (i) limiting the opening of refrigeration cycle cooling valves, including one or more of an expansion valve and a suction modulating valve, and (ii) modifying a TRU fan speed and / or a TRU compressor speed.

17. The method of claim 13, wherein the third strategy comprises: The TRU controller performs one or more of the following: (i) performing one or more diagnostic functions in advance of a predetermined schedule, or deferring performance of the one or more diagnostic functions until a predetermined geographic mission location is reached where energy is available, (ii) performing a defrost cycle based on a non-periodic triggering event, and (iii) removing, reducing and / or peak limiting electrical loads.

18. The method of claim 13, wherein the TRU controller executes the power management mode prior to and periodically during a task.

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