TRANSPORT REFRIGERATION UNIT WITH MULTIPLE VOLTAGE SOURCE ARRANGEMENTS

Abstract

A transport refrigeration unit (TRU) system is provided and includes a high-voltage power source, a low-voltage power source, at least one of the high-voltage power source and the low-voltage power source including a fuel cell configured to provide electricity to the transport refrigeration unit, a first electrical load, which is optimally powered by the high-voltage power source, a second electrical load, which is optimally powered by the low-voltage power source and an electrical distribution system by which the high-voltage power source is directly electrically connected to the first electrical load and the low-voltage power source is directly electrically connected to the second electrical load.

Claims

1. A transport refrigeration unit (TRU) system, comprising: a high-voltage power source; a low-voltage power source, at least one of the high-voltage power source and the low-voltage power source comprising a fuel cell configured to provide electricity to the transport refrigeration unit; a first electrical load, which is optimally powered by the high-voltage power source; a second electrical load, which is optimally powered by the low-voltage power source; and an electrical distribution system by which the high-voltage power source is directly electrically connected to the first electrical load and the low-voltage power source is directly electrically connected to the second electrical load.

2. The TRU system according to claim 1, wherein the high-voltage power source comprises at least one of a fuel cell and a battery.

3. The TRU system according to claim 2, wherein the high-voltage power source is plural in number.

4. The TRU system according to claim 1, wherein the low-voltage power source comprises at least one of a fuel cell and a battery.

5. The TRU system according to claim 4, wherein the low-voltage power source is plural in number.

6. The TRU system according to claim 1, wherein the first electrical load comprises at least a compressor motor.

7. The TRU system according to claim 1, wherein the second electrical load comprises at least one or more of an evaporator fan motor and a condenser fan motor.

8. The TRU system according to claim 1, wherein at least the first electrical load is controllable for optimized load operation.

9. A transport refrigeration unit (TRU) system, comprising: a high-voltage power source; a low-voltage power source, at least one of the high-voltage power source and the low-voltage power source comprising a fuel cell configured to provide electricity to the transport refrigeration unit; a first electrical load, which is optimally powered by the high-voltage power source; a second electrical load, which is optimally powered by the low-voltage power source; an electrical distribution system comprising a first linkage by which the high-voltage power source is directly electrically connected to the first electrical load and a second linkage by which the low-voltage power source is directly electrically connected to the second electrical load; and a voltage conversion unit electrically interposed between the first and second linkages and by which the high-voltage power source is selectively electrically connectable to the second electrical load and the low-voltage power source is selectively electrically connectable to the first electrical load.

10. The TRU system according to claim 9, wherein the high-voltage power source comprises at least one of a fuel cell and a battery.

11. The TRU system according to claim 10, wherein the high-voltage power source is plural in number.

12. The TRU system according to claim 9, wherein the low-voltage power source comprises at least one of a fuel cell and a battery.

13. The TRU system according to claim 12, wherein the low-voltage power source is plural in number.

14. The TRU system according to claim 9, wherein the first electrical load comprises at least a compressor motor.

15. The TRU system according to claim 9, wherein the second electrical load comprises at least one or more of an evaporator fan motor and a condenser fan motor.

16. The TRU system according to claim 9, wherein at least the first electrical load is controllable for optimized load operation.

17. The TRU system according to claim 9, wherein the voltage conversion unit is selectively engageable to allow for dynamic power allocation to at least one of the first electrical load and the second electrical load.

18. The TRU system according to claim 9, wherein the voltage conversion unit is selectively engageable for redundancy in an event of a fault in either the high-voltage power source or the low-voltage power source.

19. A method of operating a transport refrigeration unit (TRU) system, the method comprising: directly electrically connecting a high-voltage power source to a first electrical load, which is optimally powered by the high-voltage power source; directly electrically connecting a low-voltage power source to a second electrical load, which is optimally powered by the low-voltage power source; and selectively engaging a voltage conversion unit to electrically connect the high-voltage power source to the second electrical load or to electrically connect the low-voltage power source to the first electrical load.

20. The method according to claim 19, wherein the selectively engaging of the voltage conversion unit comprises at least one of: selectively engaging the voltage conversion unit to allow for dynamic power allocation to at least one of the first electrical load and the second electrical load; and selectively engaging the voltage conversion unit for redundancy in an event of a fault in either the high-voltage power source or the low-voltage power source.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The subject matter, which is regarded as the disclosure, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

[0027] FIG. 1 depicts a tractor trailer system having a transport refrigeration unit and a cargo compartment, in accordance with exemplary embodiments;

[0028] FIG. 2 depicts a transport refrigeration unit for a cargo compartment of the tractor trailer system of FIG. 1, in accordance with exemplary embodiments;

[0029] FIG. 3 is a schematic diagram of power sources for a transport refrigeration unit system, in accordance with exemplary embodiments;

[0030] FIG. 4 is a schematic diagram of power sources for a transport refrigeration unit system, in accordance with further exemplary embodiments; and

[0031] FIG. 5 is a flow diagram illustrating a method of operating a transport refrigeration unit, in accordance with exemplary embodiments.

[0032] These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

DETAILED DESCRIPTION

[0033] Fuel cells and batteries have been considered as primary power sources for electrified TRU applications. In these cases, the selection of voltage levels with certain components can sometimes become difficult. This is because different components inside of TRU systems may have different preferences of voltage levels in order to maximize the efficiency and minimize complexity. Thus, as will be described below, an electrical architecture is provided with hybrid voltage source combinations. Multiple power sources are included with some being high-voltage power sources for use with components that are better equipped to operate in high-voltage conditions and with some being low-voltage power sources for use with components that are better equipped to operate in low-voltage conditions. The high-voltage and low-voltage power sources can each include or be provided as fuel cells, battery packs or combinations thereof.

[0034] With reference to FIG. 1, a tractor trailer system 100 is provided. The tractor trailer system 100 includes a tractor 102 including an operator's compartment or cab 104 and an engine, which acts as the drive system of the tractor trailer system 100. A trailer 106 is coupled to the tractor 102. The trailer 106 is a refrigerated trailer 106 and includes a top wall 108, a directly opposed bottom wall 110, opposed side walls 112 and a front wall 114, with the front wall 114 being closest to the tractor 102. The trailer 106 further includes a door or doors (not shown) at a rear wall 116, opposite the front wall 114. The walls of the trailer 106 define a cargo compartment. The trailer 106 is configured to maintain a cargo 118 located inside the cargo compartment at a selected temperature through the use of a TRU 120 located on the trailer 106. The TRU 120, as shown in FIG. 1, can be located at or attached to the front wall 114. Although described herein that the transport refrigeration unit may be attached to a tractor trailer, it should be appreciated that the transport refrigeration unit described herein may be suitable for any refrigerated cargo system (e.g., tractor trailer, container, unit load device, etc.).

[0035] With reference to FIG. 2, the TRU 120 is shown in more detail. The TRU unit 120 includes a compressor 122, a condenser 124 with a condenser fan 1240, an expansion valve 126, an evaporator 128 and an evaporator fan 130. The compressor 122 is operably connected to a compressor motor 132.sub.1, which is receptive of power and uses that power to drive the compressor 122. The evaporator fan 130 is operably connected to an evaporator fan motor 132.sub.2, which is receptive of power and uses that power to drive the evaporator fan 130. The condenser fan 1240 is operably connected to a condenser fan motor 132.sub.3, which is receptive of power and uses that power to drive the condenser fan 1240. Airflow is circulated into and through the cargo compartment of the trailer 106 by means of the TRU 120. A return airflow 134 flows into the TRU 120 from the cargo compartment of the trailer 106 through a refrigeration unit inlet 136 and across the evaporator 128 via the evaporator fan 130, thus cooling the return airflow 134. The cooled return airflow 134, now referred to as supply airflow 138, is supplied into the cargo compartment of the trailer 106 through a refrigeration unit outlet 140, which in some embodiments is located near the top wall 108 of the trailer 106. The supply airflow 138 cools the cargo 118 in the cargo compartment of the trailer 106. Also included in the cargo compartment can be a refrigerant leak sensor 150 for detecting a leak of a particular type of refrigerant or substance. It is to be understood that the refrigerant leak sensor 150 can be located in different locations in the system and is not limited by the example shown in FIG. 2. For example, the refrigerant leak sensor 150 can be located in the evaporator section of the TRU 120, a different portion of the cargo compartment of the trailer 106 or another location in the system. Upon detection by the refrigerant leak sensor 150, a signal can be transmitted to controller 160. The controller 160 controls various aspects of the TRU 120 and the TRU power system. The controller 160 can control the compressor 122, the condenser 124, the expansion valve 126, the evaporator 128 and the evaporator fan 130 in addiction to other equipment or sensors. The controller 160 can be connected to the equipment over a wired or wireless connection (connections not shown). In some cases, the controller 160 can be configured to perform a low charge diagnostics calculation which is used to perform various calculations of the refrigeration system of the TRU 120 to determine a state of operation. In other embodiments, the low charge diagnostics calculation can be performed in a cloud network (not shown in FIG. 2).

[0036] With reference to FIGS. 3 and 4, the TRU system 300 includes a high-voltage power source 310, a low-voltage power source 320, a first electrical load 330, which is optimally powered by the high-voltage power source 310 and a second electrical load 340, which is optimally powered by the low-voltage power source 320. The TRU system 300 further includes an electrical distribution system 350. The electrical distribution system 350 includes at least a first electrical linkage 351 by which the high-voltage power source 310 is directly electrically connected to the first electrical load 330 and at least a second electrical linkage 352 by which the low-voltage power source 320 is directly electrically connected to the second electrical load 340.

[0037] The high-voltage power source 310 can provide power greater than 50 V (e.g., 145-80V) and can include or be provided as a fuel cell. The low-voltage power source 320 can provide power of less than 50V, with a nominal output of about 48V, and can include or be provided as a fuel cell. Hydrogen for a fuel cell (i.e., cryo-compressed hydrogen gas) for either the high-voltage power source 310 or the low-voltage power source 320 can be stored in a tank 1060 (e.g., below the trailer 106 as shown in FIG. 1).

[0038] In some alternative embodiments, the high-voltage power source 310 can include or be provided as at least one of a fuel cell and a battery and can be plural in number (i.e., there can be multiple high-voltage power sources 310, each being either a fuel cell or a battery). Similarly, in some other alternative embodiments, the low-voltage power source 320 can include or be provided as at least one of a fuel cell and a battery and can be plural in number (i.e., there can be multiple low-voltage power sources 320, each being either a fuel cell or a battery). In the case of either the high-voltage power source 310 or the low-voltage power source 320 being plural in number, it is to be understood that space would need to be provided in or on the refrigerated cargo system (e.g., the trailer 106 of FIG. 2).

[0039] In those cases where the high-voltage power source 310 or the low-voltage power source 320 is provided as a battery, the TRU system 300 can further include a charging element configured to recharge the battery. The structure and connections to such a charging element would be understood by a person of ordinary skill in the art.

[0040] In accordance with embodiments, and for exemplary purposes, the first electrical load 330 can include or be provided as a compressor motor, such as the compressor motor 132.sub.1 of FIG. 2, which may be a high-voltage load and which may be optimally powered by the high-voltage power source 310. In these or other cases, a fixed or variable speed motor drive 3301 can be electrically interposed between the high-voltage power source 310 and the compressor motor 132.sub.1. In an exemplary case, the fixed or variable speed motor drive 3301 can provide compatibility between the high-voltage power source 310 and the compressor motor 132.sub.1 where the compressor motor 132.sub.1 operates with alternating current (AC) at 460V/3P/60 Hz or 400V/3P/50 Hz and a fuel cell serving as the high-voltage power source 310 generates power with direct current (DC) at 145-80V.

[0041] In accordance with embodiments, the second electrical load 340 can include or be provided as one or more of an evaporator fan motor and a condenser fan motor, such as the evaporator fan motor 132.sub.2 and the condenser fan motor 132.sub.3 of FIG. 2, which may be optimally powered by the low-voltage power source 310, as well as other low-voltage loads. As above, in these or other cases, fixed or variable speed motor drives 3401 can be electrically interposed between the low-voltage power source 320 and the evaporator fan motor 132.sub.2 and the condenser fan motor 132.sub.3. In addition, a power conversion unit 3402 can be electrically interposed between the low-voltage power source 320 and the other low-voltage loads. In an exemplary case, the fixed or variable speed motor drive 3401 can provide compatibility between the low-voltage power source 320 and the evaporator fan motor 132.sub.2 and the condenser fan motor 132.sub.3.

[0042] In accordance with embodiments, at least the first electrical load 330 can be controllable for optimized load operation. In these or other cases, in the exemplary case where the first electrical load 330 is the compressor motor 132.sub.1 of FIG. 2 and the TRU system 300 further includes the fixed or variable speed motor drive 3301, the fixed or variable speed motor drive 3301 can be configured to control an operation of the compressor motor 132.sub.1 to spin up or ramp down the compressor 122 of FIG. 2 in a manner that is optimized for current conditions and for available power from the high-voltage power source 310 (and the low-voltage power source 320) and in a manner that is optimally energy efficient.

[0043] A shown in FIG. 4, the TRU system 300 can also include a voltage conversion unit 360. The voltage conversion unit 360 is electrically interposed between the first electrical linkage 351 and the second electrical linkage 352. The voltage conversion unit 360 may be selectively engageable so that the high-voltage power source 310 can be selectively electrically connectable to the second electrical load 340 and so that the low-voltage power source 320 can be selectively electrically connectable to the first electrical load 330. As such, the voltage conversion unit 360 is selectively engageable to allow for dynamic power allocation to at least one of the first electrical load 330 and the second electrical load 340. That is, in the exemplary case where the first electrical load 330 is the compressor motor 132.sub.1 of FIG. 2 and is being controlled for optimized load operation, the voltage conversion unit 360 can be selectively engaged to connect the low-voltage power source to the compressor motor 132.sub.1 for at least as long as the optimized load operation is in effect. In these or other instances, the connection between the high-voltage power source 310 and the compressor motor 132.sub.1 may be maintained though the high-voltage power source 310 may be otherwise prevented from providing power to the compressor motor 132.sub.1. In addition, the voltage conversion unit 360 can be selectively engageable for redundancy in an event of a fault in either the high-voltage power source 310 or the low-voltage power source 320 which prevents the faulty power source from providing power to an electrical load for which it would otherwise provide power.

[0044] With reference to FIG. 5, a method 500 of operating TRU system, such as the TRU system 300 of FIGS. 3 and 4, is provided. The method 500 includes directly electrically connecting a high-voltage power source to a first electrical load, which is optimally powered by the high-voltage power source (block 501), directly electrically connecting a low-voltage power source to a second electrical load, which is optimally powered by the low-voltage power source (block 502) and selectively engaging a voltage conversion unit to electrically connect the high-voltage power source to the second electrical load or to electrically connect the low-voltage power source to the first electrical load (block 503). In accordance with embodiments, the selectively engaging of the voltage conversion unit of block 503 includes at least one of selectively engaging the voltage conversion unit to allow for dynamic power allocation to at least one of the first electrical load and the second electrical load (block 5031) and selectively engaging the voltage conversion unit for redundancy in an event of a fault in either the high-voltage power source or the low-voltage power source (block 5032).

[0045] Technical effects and benefits of the present disclosure are the provision of a TRU system with a reduced number of power conversion components that provides for increased efficiency as well as minimized complexity and minimized use of space for an electrical system.

[0046] While the disclosure is provided in detail in connection with only a limited number of embodiments, it should be readily understood that the disclosure is not limited to such disclosed embodiments. Rather, the disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the disclosure. Additionally, while various embodiments of the disclosure have been described, it is to be understood that the exemplary embodiment(s) may include only some of the described exemplary aspects. Accordingly, the disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.