Electrical architecture for powering multiple transport refrigeration units

A multi-unit transport refrigeration system including: a first transportation refrigeration unit configured to refrigerate a first transport container; a second transportation refrigeration unit configured to refrigerate a second transport container; and an energy management system including: an energy storage device configured to store electricity to power the first second transportation refrigeration unit; and a power conversion system electrically connecting the energy storage device to the first transportation refrigeration unit and the second transportation refrigeration unit, the power conversion system including: a first DC/DC converter configured to increase a voltage of the electricity received from the energy storage device from a first voltage to a second voltage; and a first DC/AC inverter configured to convert the electricity received from the first DC/DC converter from DC to AC and then convey the electricity to at least one of the first transportation refrigeration unit or the second transportation refrigeration unit.

BACKGROUND

The embodiments herein generally relate to transport refrigeration systems and more specifically, the energy management of such transport refrigeration systems.

Typically, cold chain distribution systems are used to transport and distribute cargo, or more specifically perishable goods and environmentally sensitive goods (herein referred to as perishable goods) that may be susceptible to temperature, humidity, and other environmental factors. Perishable goods may include but are not limited to fruits, vegetables, grains, beans, nuts, eggs, dairy, seed, flowers, meat, poultry, fish, ice, and pharmaceuticals. Advantageously, cold chain distribution systems allow perishable goods to be effectively transported and distributed without damage or other undesirable effects.

Refrigerated vehicles and trailers are commonly used to transport perishable goods in a cold chain distribution system. A transport refrigeration system is mounted to the vehicles or to the trailer in operative association with a cargo space defined within the vehicles or trailer for maintaining a controlled temperature environment within the cargo space.

Conventionally, transport refrigeration systems used in connection with refrigerated vehicles and refrigerated trailers include a transportation refrigeration unit having a refrigerant compressor, a condenser with one or more associated condenser fans, an expansion device, and an evaporator with one or more associated evaporator fans, which are connected via appropriate refrigerant lines in a closed refrigerant flow circuit. Air or an air/gas mixture is drawn from the interior volume of the cargo space by means of the evaporator fan(s) associated with the evaporator, passed through the airside of the evaporator in heat exchange relationship with refrigerant whereby the refrigerant absorbs heat from the air, thereby cooling the air. The cooled air is then supplied back to the cargo space.

On commercially available transport refrigeration systems used in connection with refrigerated vehicles and refrigerated trailers, the compressor, and typically other components of the transportation refrigeration unit, must be powered during transit by a prime mover. In mechanically driven transport refrigeration systems the compressor is driven by the prime mover, either through a direct mechanical coupling or a belt drive, and other components, such as the condenser and evaporator fans are belt driven.

Transport refrigeration systems may also be electrically driven. In an electrically driven transport refrigeration system, a prime mover carried on and considered part of the transport refrigeration system, drives an alternating (AC) synchronous generator that generates AC power. The generated AC power is used to power an electric motor for driving the refrigerant compressor of the transportation refrigeration unit and also powering electric AC fan motors for driving the condenser and evaporator motors and electric heaters associated with the evaporator. A more efficient method to power the electric motor is desired to reduce fuel usage.

BRIEF DESCRIPTION

According to one embodiment, a multi-unit transport refrigeration system is provided. The multi-unit transport refrigeration system including: a first transportation refrigeration unit configured to refrigerate a first transport container; a second transportation refrigeration unit configured to refrigerate a second transport container; and an energy management system including: an energy storage device configured to store electricity to power the first transportation refrigeration unit and the second transportation refrigeration unit; and a power conversion system electrically connecting the energy storage device to the first transportation refrigeration unit and the second transportation refrigeration unit, the power conversion system including: a first DC/DC converter configured to increase a voltage of the electricity received from the energy storage device from a first voltage to a second voltage; and a first DC/AC inverter configured to convert the electricity received from the first DC/DC converter from DC to AC and then convey the electricity to at least one of the first transportation refrigeration unit or the second transportation refrigeration unit.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include a first electrical connection electrically connecting the first DC/DC converter to the energy storage device.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include a second electrical connection electrically connecting the first DC/AC inverter to the first transportation refrigeration unit; a third electrical connection electrically connecting the first DC/AC inverter to the second transportation refrigeration unit; and a junction point configured to split the electricity exiting the first DC/AC inverter into the second electrical connection and the third electrical connection.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include a second DC/AC inverter configured to convert the electricity received from the first DC/DC converter from DC to AC and then convey the electricity to the second transportation refrigeration unit, wherein the second DC/AC inverter is in a second path and the first DC/AC inverter is in a first circuit path, and wherein the first DC/AC inverter is configured to convey the electricity to the first transportation refrigeration unit.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include a first electrical connection electrically connecting the energy storage device to the first DC/DC converter; and a junction point configured to split the electricity exiting the first DC/DC converter into the first DC/AC inverter and the second DC/AC inverter.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include: a second electrical connection electrically connecting the first DC/AC inverter to the first transportation refrigeration unit; and a third electrical connection electrically connecting the second DC/AC inverter to the second transportation refrigeration unit.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include a second DC/DC converter configured to increase the voltage of the electricity received from the energy storage device from the first voltage to a third voltage, wherein the second DC/DC converter is in a second circuit path and the first DC/DC converter is in a first circuit path; and a second DC/AC inverter configured to convert the electricity received from the second DC/DC converter from DC to AC and then convey the electricity to the second transportation refrigeration unit, wherein the second DC/AC inverter is in the second circuit path and the first DC/AC inverter is in the first circuit path, and wherein the first DC/AC inverter is configured to convey the electricity to the first transportation refrigeration unit.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include: a first electrical connection electrically connecting the energy storage device to the first DC/DC converter and the second DC/DC converter; and a junction point configured to split the electricity exiting the energy storage device into the first DC/DC converter and the second DC/DC converter.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include: a second electrical connection electrically connecting the first DC/AC inverter to the first transportation refrigeration unit; and a third electrical connection electrically connecting the second DC/AC inverter to the second transportation refrigeration unit.

According to another embodiment, a method of operating a multi-unit transport refrigeration system is provided. The method including: refrigerating a first transport container using a first transportation refrigeration unit; refrigerating a second transport container using a second transportation refrigeration unit; storing electricity to power the first transportation refrigeration unit and the second transportation refrigeration unit using an energy storage device; increasing, using a first DC/DC converter, a voltage of the electricity received from the energy storage device from a first voltage to a second voltage; and converting, using a first DC/AC inverter, the electricity received from the first DC/DC converter from DC to AC and conveying the electricity to at least one of the first transportation refrigeration unit or the second transportation refrigeration unit.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include conveying the electricity from the energy storage device to the first DC/DC converter using a first electrical connection.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include: conveying the electricity from the first DC/AC inverter to the first transportation refrigeration unit using a second electrical connection; conveying the electricity from the first DC/AC inverter to the second transportation refrigeration unit using a third electrical connection; and splitting the electricity exiting the first DC/AC inverter into the second electrical connection and third electrical connection using a junction point.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include: converting, using a second DC/AC inverter, the electricity received from the first DC/DC converter from DC to AC and conveying the electricity to the second transportation refrigeration unit, wherein the second DC/AC inverter is in a second circuit path and the first DC/AC inverter is in a first circuit path, and wherein the first DC/AC inverter is configured to convey the electricity to the first transportation refrigeration unit.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include: conveying the electricity from the energy storage device to the first DC/DC converter using a first electrical connection; and splitting the electricity exiting the first DC/DC converter into the first DC/AC inverter and the second DC/AC inverter using a junction point.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include: conveying the electricity from the first DC/AC inverter to the first transportation refrigeration unit using a second electrical connection; and conveying the electricity from the second DC/AC inverter to the second transportation refrigeration unit using a third electrical connection.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include: increasing, using a second DC/DC converter, the voltage of the electricity received from the energy storage device from the first voltage to a third voltage, wherein the second DC/DC converter is in a second circuit path and the first DC/DC converter is in a first circuit path; and converting, using a second DC/AC inverter, the electricity received from the second DC/DC converter from DC to AC and conveying the electricity to the second transportation refrigeration unit, wherein the second DC/AC inverter is the second circuit path and the first DC/AC inverter is in the first circuit path, and wherein the first DC/AC inverter is configured to convey the electricity to the first transportation refrigeration unit.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include: conveying the electricity from the energy storage device to the first DC/DC converter and the second DC/DC converter using a first electrical connection; and splitting, using a junction point, the electricity exiting the energy storage device into the first DC/DC converter and the second DC/DC converter.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include conveying the electricity from the first DC/AC inverter to the first transportation refrigeration unit using a second electrical connection; and conveying the electricity from the second DC/AC inverter to the second transportation refrigeration unit using a third electrical connection.

According to another embodiment, a method of assembling a multi-unit transport refrigeration system is provided. The method including: operably connecting a first transportation refrigeration unit to a first transport container, the first transportation refrigeration unit configured to refrigerate the first transport container; operably connecting a second transportation refrigeration unit to a second transport container, the second transportation refrigeration unit configured to refrigerate the second transport container; electrically connecting an energy storage device and a first DC/DC converter, the first DC/DC converter being configured to increase a voltage of the electricity received from the energy storage device from a first voltage to a second voltage; and electrically connecting the first DC/DC converter to the first transportation refrigeration unit and the second transportation refrigeration unit using at least a first DC/AC inverter, the first DC/AC inverter configured to convert electricity received from the energy storage device from DC to AC and then convey the electricity to at least one of the first transportation refrigeration unit or the second transportation refrigeration unit.

In addition to one or more of the features described above, or as an alternative, further embodiments of the transport refrigeration system may include: electrically connecting the energy storage device to the first DC/DC converter using a first electrical connection.

Technical effects of embodiments of the present disclosure include converting electricity stored in an energy storage device from direct current to alternating current and splitting the electricity to distribute to a first transportation refrigeration unit and a second transportation refrigeration unit.

DETAILED DESCRIPTION

Referring toFIGS.1,2, and3, various embodiments of the present disclosure are illustrated.FIG.1shows a schematic illustration of a multi-unit transport refrigeration system100, including a first transport refrigeration system200aand a second transport refrigeration system200b,according to an embodiment of the present disclosure. The multi-unit transport refrigeration system100, may be incorporated into a truck or trailer system101, as illustrated inFIG.1.FIG.2shows an enlarged schematic illustration of the first transport refrigeration system200aofFIG.1, according to an embodiment of the present disclosure.FIG.3shows an enlarged schematic illustration of the second transport refrigeration system200bofFIG.1, according to an embodiment of the present disclosure.

The trailer system101includes a vehicle102integrally connected to a first transport container106aand a second transport container106b.The vehicle102includes an operator's compartment or cab104and a propulsion motor, which acts as the drive system of the truck or trailer system101. The propulsion motor is configured to power the vehicle102. The propulsion motor may be a combustion engine320that runs on a fuel, such as, compressed natural gas, liquefied natural gas, gasoline, diesel, or a combination thereof. The propulsion motor may be an electric motor324that runs on electricity from a truck energy storage device326(e.g., battery pack) and/or an energy storage device350. The propulsion motor may also be a combination of the combustion engine320and the electric motor324, such as, for example, a hybrid motor. It is understood that while both a combustion engine320and the electric motor324are illustrated inFIG.1, the embodiments disclosed herein apply to a propulsion motor composed of the combustion engine320and/or the electric motor324. The combustion engine320may be operably connected to a vehicle alternator322to generate electricity. The electricity generated by the vehicle alternator322may be utilized to charge the truck energy storage device326.

Referring first to the first transport refrigeration system200a,the first transport container106ais coupled to the vehicle102. The first transport container106amay be removably coupled to the vehicle102. The first transport container106ais a refrigerated trailer and includes a top wall108a,a directly opposed bottom wall110a,opposed side walls112a,and a front wall114a,with the front wall114abeing closest to the vehicle102. The first transport container106afurther includes a door or doors117aat a rear wall116a,opposite the front wall114a.The walls of the first transport container106adefine a refrigerated cargo space119a.The first refrigerated cargo space119amay be subdivided into multiple different compartments that each have a different controlled environment (e.g., different temperature). It is appreciated by those of skill in the art that embodiments described herein may be applied to a tractor-trailer refrigerated system or non-trailer refrigeration such as, for example a rigid truck, a truck having refrigerated compartment.

Typically, the first transport refrigeration system200aare used to transport and distribute perishable goods and environmentally sensitive goods (herein referred to as perishable goods118a). The perishable goods118amay include but are not limited to fruits, vegetables, grains, beans, nuts, eggs, dairy, seed, flowers, meat, poultry, fish, ice, blood, pharmaceuticals, or any other suitable cargo requiring temperature controlled transport. The first transport refrigeration system200aincludes a first transportation refrigeration unit22a,a refrigerant compression device32a,an electric motor26afor driving the refrigerant compression device32a,and a controller30a.The first transportation refrigeration unit22ais in operative association with the refrigerated cargo space119aand is configured to provide conditioned air to the first transport container106a.The first transportation refrigeration unit22afunctions, under the control of the controller30a,to establish and regulate a desired environmental parameters, such as, for example temperature, pressure, humidity, carbon dioxide, ethylene, ozone, light exposure, vibration exposure, and other conditions in the first refrigerated cargo space119a,as known to one of ordinary skill in the art. In an embodiment, the first transportation refrigeration unit22ais capable of providing a desired temperature and humidity range.

The first transportation refrigeration unit22aincludes a refrigerant compression device32a(e.g., compressor), a refrigerant heat rejection heat exchanger34a(e.g., condenser), an expansion device36a,and a refrigerant heat absorption heat exchanger38a(e.g., evaporator) connected in refrigerant flow communication in a closed loop refrigerant circuit and arranged in a conventional refrigeration cycle. The first transportation refrigeration unit22aalso includes one or more fans40aassociated with the refrigerant heat rejection heat exchanger34aand driven by fan motor(s)42aand one or more fans44aassociated with the refrigerant heat absorption heat exchanger38aand driven by fan motor(s)46a.The first transportation refrigeration unit22amay also include a heater48aassociated with the refrigerant heat absorption heat exchanger38a.In an embodiment, the heater48amay be an electric resistance heater. It is to be understood that other components (not shown) may be incorporated into the refrigerant circuit as desired, including for example, but not limited to, a suction modulation valve, a receiver, a filter/dryer, an economizer circuit. It is also to be understood that additional refrigeration circuits may be run in parallel and powered by an energy storage device350as desired.

The refrigerant heat rejection heat exchanger34amay, for example, include one or more refrigerant conveying coiled tubes or one or more tube banks formed of a plurality of refrigerant conveying tubes across flow path to the heat outlet142a.The fan(s)40aare operative to pass air, typically ambient air, across the tubes of the refrigerant heat rejection heat exchanger34ato cool refrigerant vapor passing through the tubes. The refrigerant heat rejection heat exchanger34amay operate either as a refrigerant condenser, such as if the first transportation refrigeration unit22ais operating in a subcritical refrigerant cycle or as a refrigerant gas cooler, such as if the first transportation refrigeration unit22ais operating in a transcritical cycle.

The refrigerant heat absorption heat exchanger38amay, for example, also include one or more refrigerant conveying coiled tubes or one or more tube banks formed of a plurality of refrigerant conveying tubes extending across flow path from a return air intake136a.The fan(s)44aare operative to pass air drawn from the refrigerated cargo space119aacross the tubes of the refrigerant heat absorption heat exchanger38ato heat and evaporate refrigerant liquid passing through the tubes and cool the air. The air cooled in traversing the refrigerant heat absorption heat exchanger38ais supplied back to the refrigerated cargo space119athrough a refrigeration unit outlet140a.It is to be understood that the term “air” when used herein with reference to the atmosphere within the cargo box includes mixtures of air with other gases, such as for example, but not limited to, nitrogen or carbon dioxide, sometimes introduced into a refrigerated cargo box for transport of perishable produce.

Airflow is circulated into and through the first refrigerated cargo space119aof the first transport container106aby means of the first transportation refrigeration unit22a.A return airflow134aflows into the first transportation refrigeration unit22afrom the refrigerated cargo space119athrough the return air intake136a,and across the refrigerant heat absorption heat exchanger38avia the fan44a,thus conditioning the return airflow134ato a selected or predetermined temperature. The conditioned return airflow134a,now referred to as supply airflow138a,is supplied into the first refrigerated cargo space119aof the first transport container106athrough the refrigeration unit outlet140a.Heat135ais removed from the refrigerant heat rejection heat exchanger34athrough the heat outlet142a.The first transportation refrigeration unit22amay contain an external air inlet144a,as shown inFIG.2, to aid in the removal of heat135afrom the refrigerant heat rejection heat exchanger34aby pulling in external air137a.The supply airflow138amay cool the perishable goods118ain the first refrigerated cargo space119aof the first transport container106a.It is to be appreciated that the first transportation refrigeration unit22acan further be operated in reverse to warm the first transport container106awhen, for example, the outside temperature is very low. In the illustrated embodiment, the return air intake136a,the refrigeration unit outlet140a,the heat outlet142a,and the external air inlet144aare configured as grilles to help prevent foreign objects from entering the first transportation refrigeration unit22a.

The first transport refrigeration system200aalso includes a controller30aconfigured for controlling the operation of the first transport refrigeration system200aincluding, but not limited to, the operation of various components of the first transportation refrigeration unit22ato provide and maintain a desired thermal environment within the first refrigerated cargo space119a.The controller30amay also be able to selectively operate the electric motor26a.The controller30amay be an electronic controller including a processor and an associated memory including computer-executable instructions that, when executed by the processor, cause the processor to perform various operations. The processor may be but is not limited to a single-processor or multi-processor system of any of a wide array of possible architectures, including field programmable gate array (FPGA), central processing unit (CPU), application specific integrated circuits (ASIC), digital signal processor (DSP) or graphics processing unit (GPU) hardware arranged homogenously or heterogeneously. The memory may be a storage device such as, for example, a random access memory (RAM), read only memory (ROM), or other electronic, optical, magnetic or any other computer readable medium.

Referring next to the second transport refrigeration system200b,the second transport container106bis coupled to the vehicle102. The second transport container106bmay be removably coupled to the vehicle102. The second transport container106bis a refrigerated trailer and includes a top wall108b,a directly opposed bottom wall110b,opposed side walls112b,and a front wall114b,with the front wall114bbeing closest to the vehicle102. The second transport container106bfurther includes a door or doors117bat a rear wall116b,opposite the front wall114b.The walls of the second transport container106bdefine a refrigerated cargo space119b. The second refrigerated cargo space119bmay be subdivided into multiple different compartments that each have a different controlled environment (e.g., different temperature). It is appreciated by those of skill in the art that embodiments described herein may be applied to a tractor-trailer refrigerated system or non-trailer refrigeration such as, for example a rigid truck, a truck having refrigerated compartment.

Typically, the second transport refrigeration system200bare used to transport and distribute perishable goods and environmentally sensitive goods (herein referred to as perishable goods118a). The perishable goods118bmay include but are not limited to fruits, vegetables, grains, beans, nuts, eggs, dairy, seed, flowers, meat, poultry, fish, ice, blood, pharmaceuticals, or any other suitable cargo requiring temperature controlled transport. The second transport refrigeration system200bincludes a second transportation refrigeration unit22b,a refrigerant compression device32b,an electric motor26bfor driving the refrigerant compression device32b,and a controller30b.The second transportation refrigeration unit22bis in operative association with the refrigerated cargo space119band is configured to provide conditioned air to the second transport container106b.The second transportation refrigeration unit22bfunctions, under the control of the controller30b,to establish and regulate a desired environmental parameters, such as, for example temperature, pressure, humidity, carbon dioxide, ethylene, ozone, light exposure, vibration exposure, and other conditions in the second refrigerated cargo space119b,as known to one of ordinary skill in the art. In an embodiment, the second transportation refrigeration unit22bis capable of providing a desired temperature and humidity range.

The second transportation refrigeration unit22bincludes a refrigerant compression device32b(e.g., compressor), a refrigerant heat rejection heat exchanger34b(e.g., condenser), an expansion device36b,and a refrigerant heat absorption heat exchanger38b(e.g., evaporator) connected in refrigerant flow communication in a closed loop refrigerant circuit and arranged in a conventional refrigeration cycle. The second transportation refrigeration unit22balso includes one or more fans40bassociated with the refrigerant heat rejection heat exchanger34band driven by fan motor(s)42band one or more fans44bassociated with the refrigerant heat absorption heat exchanger38band driven by fan motor(s)46b.The second transportation refrigeration unit22bmay also include a heater48bassociated with the refrigerant heat absorption heat exchanger38b.In an embodiment, the heater48bmay be an electric resistance heater. It is to be understood that other components (not shown) may be incorporated into the refrigerant circuit as desired, including for example, but not limited to, a suction modulation valve, a receiver, a filter/dryer, an economizer circuit. It is also to be understood that additional refrigeration circuits may be run in parallel and powered by an energy storage device350as desired.

The refrigerant heat rejection heat exchanger34bmay, for example, include one or more refrigerant conveying coiled tubes or one or more tube banks formed of a plurality of refrigerant conveying tubes across flow path to the heat outlet142b.The fan(s)40bare operative to pass air, typically ambient air, across the tubes of the refrigerant heat rejection heat exchanger34bto cool refrigerant vapor passing through the tubes. The refrigerant heat rejection heat exchanger34bmay operate either as a refrigerant condenser, such as if the second transportation refrigeration unit22bis operating in a subcritical refrigerant cycle or as a refrigerant gas cooler, such as if the second transportation refrigeration unit22bis operating in a transcritical cycle.

The refrigerant heat absorption heat exchanger38bmay, for example, also include one or more refrigerant conveying coiled tubes or one or more tube banks formed of a plurality of refrigerant conveying tubes extending across flow path from a return air intake136b.The fan(s)44bare operative to pass air drawn from the refrigerated cargo space119bacross the tubes of the refrigerant heat absorption heat exchanger38bto heat and evaporate refrigerant liquid passing through the tubes and cool the air. The air cooled in traversing the refrigerant heat absorption heat exchanger38bis supplied back to the refrigerated cargo space119bthrough a refrigeration unit outlet140b.It is to be understood that the term “air” when used herein with reference to the atmosphere within the cargo box includes mixtures of air with other gases, such as for example, but not limited to, nitrogen or carbon dioxide, sometimes introduced into a refrigerated cargo box for transport of perishable produce.

Airflow is circulated into and through the second refrigerated cargo space119bof the second transport container106bby means of the second transportation refrigeration unit22b.a return airflow134bflows into the second transportation refrigeration unit22bfrom the refrigerated cargo space119bthrough the return air intake136b,and across the refrigerant heat absorption heat exchanger38bvia the fan44b,thus conditioning the return airflow134bto a selected or predetermined temperature. The conditioned return airflow134b,now referred to as supply airflow138b,is supplied into the second refrigerated cargo space119bof the second transport container106bthrough the refrigeration unit outlet140b.Heat135bis removed from the refrigerant heat rejection heat exchanger34bthrough the heat outlet142b.The second transportation refrigeration unit22bmay contain an external air inlet144b,as shown inFIG.2, to aid in the removal of heat135bfrom the refrigerant heat rejection heat exchanger34bby pulling in external air137b.The supply airflow138bmay cool the perishable goods118bin the second refrigerated cargo space119bof the second transport container106b.It is to be appreciated that the second transportation refrigeration unit22bcan further be operated in reverse to warm the second transport container106bwhen, for example, the outside temperature is very low. In the illustrated embodiment, the return air intake136b,the refrigeration unit outlet140b,the heat outlet142b,and the external air inlet144bare configured as grilles to help prevent foreign objects from entering the second transportation refrigeration unit22b.

The second transport refrigeration system200balso includes a controller30bconfigured for controlling the operation of the second transport refrigeration system200bincluding, but not limited to, the operation of various components of the second transportation refrigeration unit22bto provide and maintain a desired thermal environment within the second refrigerated cargo space119b.The controller30bmay also be able to selectively operate the electric motor26b.The controller30bmay be an electronic controller including a processor and an associated memory including computer-executable instructions that, when executed by the processor, cause the processor to perform various operations. The processor may be but is not limited to a single-processor or multi-processor system of any of a wide array of possible architectures, including field programmable gate array (FPGA), central processing unit (CPU), application specific integrated circuits (ASIC), digital signal processor (DSP) or graphics processing unit (GPU) hardware arranged homogenously or heterogeneously. The memory may be a storage device such as, for example, a random access memory (RAM), read only memory (ROM), or other electronic, optical, magnetic or any other computer readable medium.

The first transportation refrigeration unit22aand the second transportation refrigeration unit22bare powered by the energy management system300or more specifically the energy storage device350, which provides electricity to the first transportation refrigeration unit22aand the second transportation refrigeration unit22b.The energy management system300may include the energy storage device350, a power conversion system370, and a power management system310. Examples of the energy storage device350may include a battery system (e.g., a battery, a battery pack, or bank of batteries), fuel cells, flow battery, and others devices capable of storing and outputting electricity that may be direct current (DC). The energy storage device350may include a battery system, which may employ multiple batteries organized into battery banks. In one embodiment, the energy storage device350may provide electricity to the first transportation refrigeration unit22aand the second transportation refrigeration unit22b.The energy storage device350may be located with the vehicle102.

The energy storage device350may be charged by a stationary charging station386such as, for example a wall 48V power outlet. The charging station386may provide single phase (e.g., level 2 charging capability) or three phase alternating current (AC) energy to the energy storage device350. It is understood that the charging station386may have any phase charging and embodiments disclosed herein are not limited to single phase or three phase AC power. In an embodiment, the single phase AC power may be a high voltage DC power, such as, for example, between 48 to 900 VDC.

The first transportation refrigeration unit22ahas a plurality of electrical power demand loads on the energy storage device350, including, but not limited to, the electric motor26afor the refrigerant compression device32a,the fan motor42afor the fan40aassociated with the refrigerant heat rejection heat exchanger34a,and the fan motor46afor the fan44aassociated with the refrigerant heat absorption heat exchanger38a.In the depicted embodiment, the heater48aalso constitutes an electrical power demand load. The electric resistance heater48amay be selectively operated by the controller30awhenever a control temperature within the temperature controlled cargo box drops below a preset lower temperature limit, which may occur in a cold ambient environment. In such an event the controller30awould activate the heater48ato heat air circulated over the heater48aby the fan(s)44aassociated with the refrigerant heat absorption heat exchanger38a.The heater48amay also be used to de-ice the return air intake136a.The refrigerant compression device32amay include a single-stage or multiple-stage compressor such as, for example, a reciprocating compressor or a scroll compressor. The first transport refrigeration system200amay also include a voltage sensor28ato sense the incoming voltage.

Likewise, the second transportation refrigeration unit22bhas a plurality of electrical power demand loads on the energy storage device350, including, but not limited to, the electric motor26bfor the refrigerant compression device32b,the fan motor42bfor the fan40bassociated with the refrigerant heat rejection heat exchanger34b,and the fan motor46bfor the fan44bassociated with the refrigerant heat absorption heat exchanger38b.In the depicted embodiment, the heater48balso constitutes an electrical power demand load. The electric resistance heater48bmay be selectively operated by the controller30bwhenever a control temperature within the temperature controlled cargo box drops below a preset lower temperature limit, which may occur in a cold ambient environment. In such an event the controller30bwould activate the heater48bto heat air circulated over the heater48bby the fan(s)44bassociated with the refrigerant heat absorption heat exchanger38b.The heater48bmay also be used to de-ice the return air intake136b.The refrigerant compression device32bmay include a single-stage or multiple-stage compressor such as, for example, a reciprocating compressor or a scroll compressor. The second transport refrigeration system200bmay also include a voltage sensor28bto sense the incoming voltage.

The power management system310may be configured to control and/or adjust the energy output of the energy storage device350in response to transportation refrigeration unit parameters of the first transportation refrigeration unit22aand the second transportation refrigeration unit22b.The transportation refrigeration unit parameters may include but are not limited to set point, ambient temperature, delta T° between the temperature in the refrigerated cargo spaces119a,119band the temperature set point of the transportation refrigeration unit22a,22b,airflow rate into or out of the transport container106a,106b,cooling capacity, temperature homogeneity in the transport container106a,106b,doors117a,117bopening situation . . . etc. Transportation refrigeration unit parameters, such as delta T° may be important because a high delta T° may indicate that an increase energy is required for pull down or pull up. The power management system310is in electrical communication with the energy storage device350and the power conversion system370. The power conversion system370electrically connects the energy storage device350to the first transportation refrigeration unit22aand the second transportation refrigeration unit22b.The power management system310may also be in electrical communication with the energy storage device350. The power management system310may be configured to control and/or adjust energy output of the power conversion system370in response to parameters of the energy storage device350, including, but not limited to, a state of charge of the energy storage device350a state of health of the energy storage device350, and a temperature of the energy storage device350.

It should be appreciated that, although particular components of the energy management system300are separately defined in the schematic block diagram ofFIG.1, each or any of the components may be otherwise combined or separated via hardware and/or software. In one example, while the power management system310is illustrated inFIG.1as being separate from the transportation refrigeration unit22a,22b,in various embodiments, the power management system310may be incorporated into the transportation refrigeration unit22a,22band/or the controller30a,30bof the transportation refrigeration unit22a,22b.In an embodiment, the power management system310may be a computer program product (e.g., software) encoded within controller30a,30b.In another example, while the power conversion system370is illustrated inFIG.1as being separate from the energy storage device350and the transportation refrigeration unit22a,22b,in various embodiments, the power conversion system370may be incorporated in the energy storage device350or the transportation refrigeration unit22a,22b.In one embodiment, the power conversion system370is incorporated in the energy storage device350. In another embodiment, the power conversion system370is separate from the energy storage device350(i.e., not incorporated in the energy storage device350).

The power management system310may be an electronic controller including a processor and an associated memory including computer-executable instructions that, when executed by the processor, cause the processor to perform various operations. The processor may be but is not limited to a single-processor or multi-processor system of any of a wide array of possible architectures, including field programmable gate array (FPGA), central processing unit (CPU), application specific integrated circuits (ASIC), digital signal processor (DSP) or graphics processing unit (GPU) hardware arranged homogenously or heterogeneously. The memory may be a storage device such as, for example, a random access memory (RAM), read only memory (ROM), or other electronic, optical, magnetic or any other computer readable medium.

The power conversion system370is electrically connected to the energy storage device350via a first electrical connection410. The first electrical connection410may be an electrical wire configured to convey DC. The first transportation refrigeration unit22ais electrically connected to the power conversion system370via a second electrical connection420. The second electrical connection420may be an electrical wire configured to convey AC. The second transportation refrigeration unit22bis electrically connected to the power conversion system370via a third electrical connection430. The third electrical connection430may be an electrical wire configured to convey AC. It will be appreciated that the multi-unit transport refrigeration system100described herein may incorporate any one of the electrical architectures400,500,600,700,800shown inFIGS.4-8, each of which include at least a first DC/AC inverter374(and multiple of which further include a first DC/DC converter372).

Referring now toFIG.4, a first electrical architecture400for the multi-unit transport refrigeration system100ofFIG.1is illustrated, according to an embodiment of the present disclosure. The first electrical architecture400is configured to distribute electricity from the energy storage device350to a first transportation refrigeration unit22aand a second transportation refrigeration unit22b.The electricity from the energy storage device350powers the first transportation refrigeration unit22a,which is configured to refrigerate the first transport container106a.The electricity from the energy storage device350powers the second transportation refrigeration unit22b,which is configured to refrigerate the second transport container106b.

As illustrated inFIG.4, the energy storage device350is electrically connected to the power conversion system370. The power conversion system370includes a first DC/DC converter372, a first DC/AC inverter374, a second DC/DC converter376, and a second DC/AC inverter378. The first DC/DC converter372is in series with the first DC/AC inverter374. The second DC/DC converter376is in series with the second DC/AC inverter378. The first DC/DC converter372and the first DC/AC inverter374are in a first circuit path480and the second DC/DC converter376and the second DC/AC inverter378are in a second circuit path490. The first DC/DC converter372and the second DC/DC converter376are electrically connected to the energy storage device350through the first electrical connection410. Electricity received with the energy storage device350to the power conversion system370is split between the first DC/DC converter372and the second DC/DC converter376. Electricity entering the power conversion system370is split at a junction point411into the first DC/DC converter372and the second DC/DC converter376. Electricity exiting the energy storage device350is split at a junction point411into the first DC/DC converter372and the second DC/DC converter376. The first DC/DC converter372and the second DC/DC converter376are configured to increase or boost the voltage of the electricity received from the energy storage device350.

The first DC/DC converter372is configured to increase the voltage received from the energy storage device350from a first voltage to a second voltage and then deliver the electricity at the second voltage to the first DC/AC inverter374. The second voltage is greater than the first voltage. The first DC/AC inverter374is electrically connected to the first DC/DC converter372. The first DC/AC inverter374is configured to convert the electricity received from the first DC/DC converter372from DC to AC and then convey the electricity to the first transportation refrigeration unit22a.The first DC/AC inverter374is electrically connected to the first transportation refrigeration unit22avia the second electrical connection420.

The second DC/DC converter376is configured to increase the voltage received from the energy storage device350from a first voltage to a third voltage and then deliver the electricity at the third voltage to the second DC/AC inverter378. The third voltage is greater than the first voltage. The third voltage may also be equivalent to the second voltage. The second DC/AC inverter378is electrically connected to the second DC/DC converter376. The second DC/AC inverter378is configured to convert the electricity received from the second DC/DC converter376from DC to AC and then convey the electricity to the second transportation refrigeration unit22b.The second DC/AC inverter378is electrically connected to the second transportation refrigeration unit22bvia the third electrical connection430.

Referring now toFIG.5, a second electrical architecture500for the multi-unit transport refrigeration system100ofFIG.1is illustrated, according to an embodiment of the present disclosure. The second electrical architecture500is configured to distribute electricity from the energy storage device350to a first transportation refrigeration unit22aand a second transportation refrigeration unit22b. The electricity from the energy storage device350powers the first transportation refrigeration unit22a,which is configured to refrigerate the first transport container106a.The electricity from the energy storage device350powers the second transportation refrigeration unit22b,which is configured to refrigerate the second transport container106b.

As illustrated inFIG.5, the energy storage device350is electrically connected to the power conversion system370. The power conversion system370includes a first DC/DC converter372and a first DC/AC inverter374. The first DC/DC converter372is in series with the first DC/AC inverter374. The first DC/DC converter372is electrically connected to the energy storage device350through the first electrical connection410. Electricity received with the energy storage device350to the power conversion system370is delivered to the first DC/DC converter372. The first DC/DC converter372is configured to increase or boost the voltage of the electricity received from the energy storage device350.

The first DC/DC converter372is configured to increase the voltage received from the energy storage device350from a first voltage to a second voltage and then deliver the electricity at the second voltage to the first DC/AC inverter374. The second voltage is greater than the first voltage. The first DC/AC inverter374is electrically connected to the first DC/DC converter372. The first DC/AC inverter374is configured to convert the electricity received from the first DC/DC converter372from DC to AC and then convey the electricity to the first transportation refrigeration unit22aand the second transportation refrigeration unit22b.The first DC/AC inverter374is electrically connected to the first transportation refrigeration unit22avia the second electrical connection420. The first DC/AC inverter374is electrically connected to the second transportation refrigeration unit22bvia the third electrical connection430. Electricity exiting the first DC/AC inverter374may be split at a junction point510into the second electrical connection420and the third electrical connection430.

Referring now toFIG.6, a third electrical architecture600for the multi-unit transport refrigeration system100ofFIG.1is illustrated, according to an embodiment of the present disclosure. The third electrical architecture600is configured to distribute electricity from the energy storage device350to a first transportation refrigeration unit22aand a second transportation refrigeration unit22b. The electricity from the energy storage device350powers the first transportation refrigeration unit22a,which is configured to refrigerate the first transport container106a.The electricity from the energy storage device350powers the second transportation refrigeration unit22b,which is configured to refrigerate the second transport container106b.

As illustrated inFIG.6, the energy storage device350is electrically connected to the power conversion system370. The power conversion system370includes a first DC/DC converter372, a first DC/AC inverter374, and a second DC/AC inverter378. The first DC/DC converter372is in series with the first DC/AC inverter374and the second DC/AC inverter378. The first DC/AC inverter374is in a first circuit path680and the second DC/AC inverter378is in a second circuit path690. The first DC/DC converter372is electrically connected to the energy storage device350through the first electrical connection410. Electricity received with the energy storage device350to the power conversion system370is conveyed to the first DC/DC converter372.

Electricity exiting the first DC/DC converter372is split at a junction point610into the first DC/AC inverter374and the second DC/AC inverter378. The first DC/DC converter372is configured to increase or boost the voltage of the electricity received from the energy storage device350.

The first DC/DC converter372is configured to increase the voltage received from the energy storage device350from a first voltage to a second voltage and then deliver the electricity at the second voltage to the first DC/AC inverter374and the second DC/AC inverter378. The second voltage is greater than the first voltage. The first DC/AC inverter374is electrically connected to the first DC/DC converter372. The first DC/AC inverter374is configured to convert the electricity received from the first DC/DC converter372from DC to AC and then convey the electricity to the first transportation refrigeration unit22a.The first DC/AC inverter374is electrically connected to the first transportation refrigeration unit22avia the second electrical connection420.

The second DC/AC inverter378is electrically connected to the first DC/DC converter372. The second DC/AC inverter378is configured to convert the electricity received from the first DC/DC converter372from DC to AC and then convey the electricity to the second transportation refrigeration unit22b.The second DC/AC inverter378is electrically connected to the second transportation refrigeration unit22bvia the third electrical connection430.

Referring now toFIG.7, a fourth electrical architecture700for the multi-unit transport refrigeration system100ofFIG.1is illustrated, according to an embodiment of the present disclosure. The fourth electrical architecture700is configured to distribute electricity from the energy storage device350to a first transportation refrigeration unit22aand a second transportation refrigeration unit22b. The electricity from the energy storage device350powers the first transportation refrigeration unit22a,which is configured to refrigerate the first transport container106a.The electricity from the energy storage device350powers the second transportation refrigeration unit22b,which is configured to refrigerate the second transport container106b.

As illustrated inFIG.7, the energy storage device350is electrically connected to the power conversion system370. The power conversion system370includes a first DC/AC inverter374. The first DC/AC inverter374is electrically connected to the energy storage device350through the first electrical connection410. Electricity received with the energy storage device350to the power conversion system370is delivered the first DC/AC inverter374.

The first DC/AC inverter374is configured to convert the electricity received from the energy storage device350from DC to AC and then convey the electricity to the first transportation refrigeration unit22aand the second transportation refrigeration unit22b.The first DC/AC inverter374is electrically connected to the first transportation refrigeration unit22avia the second electrical connection420. The first DC/AC inverter374is electrically connected to the second transportation refrigeration unit22bvia the third electrical connection430. Electricity exiting the first DC/AC inverter374may be split at a junction point710into the second electrical connection420and the third electrical connection430.

Referring now toFIG.8, a fifth electrical architecture800for the multi-unit transport refrigeration system100ofFIG.1is illustrated, according to an embodiment of the present disclosure. The fifth electrical architecture800is configured to distribute electricity from the energy storage device350to a first transportation refrigeration unit22aand a second transportation refrigeration unit22b. The electricity from the energy storage device350powers the first transportation refrigeration unit22a,which is configured to refrigerate the first transport container106a.The electricity from the energy storage device350powers the second transportation refrigeration unit22b,which is configured to refrigerate the second transport container106b.

As illustrated inFIG.8, the energy storage device350is electrically connected to the power conversion system370. The power conversion system370includes a first DC/AC inverter374and a second DC/AC inverter378. The first DC/AC inverter374is in a first circuit path880and the second DC/AC inverter378is in a second circuit path890. The first DC/AC inverter374and the second DC/AC inverter378are electrically connected to the energy storage device350through the first electrical connection410. Electricity received with the energy storage device350to the power conversion system370is conveyed to the first DC/AC inverter374and the second DC/AC inverter378. Electricity exiting the energy storage device350is split at a junction point810into the first DC/AC inverter374and the second DC/AC inverter378.

The first DC/AC inverter374is configured to convert the electricity received from the energy storage device350from DC to AC and then convey the electricity to the first transportation refrigeration unit22a.The first DC/AC inverter374is electrically connected to the first transportation refrigeration unit22avia the second electrical connection420.

The second DC/AC inverter378is electrically connected to the energy storage device350. The second DC/AC inverter378is configured to convert the electricity received from the energy storage device350from DC to AC and then convey the electricity to the second transportation refrigeration unit22b.The second DC/AC inverter378is electrically connected to the second transportation refrigeration unit22bvia the third electrical connection430.

Referring now toFIG.9, with continued reference toFIGS.4-6.FIG.9shows a flow process illustrating a method900of operating a multi-unit transport refrigeration system100, according to an embodiment of the present disclosure.

At block904, a first transportation refrigeration unit22arefrigerates a first transport container106a.At block906, a second transportation refrigeration unit22brefrigerates a second transport container106b.At block908, electricity to power the first transportation refrigeration unit22aand the second transportation refrigeration unit22bis stored using an energy storage device350. At block910, first DC/DC converter372increases a voltage of the electricity received from the energy storage device350from a first voltage to a second voltage. At block912, a first DC/AC inverter374converts the electricity received from the first DC/DC converter372from DC to AC and conveys the electricity to at least one of the first transportation refrigeration unit22aor the second transportation refrigeration unit22b.

The method900may further provide that the electricity is conveyed from the energy storage device350to the first DC/DC converter372using a first electrical connection410, from the first DC/AC inverter374to the first transportation refrigeration unit22ausing a second electrical connection420, and from the first DC/AC inverter374to the second transportation refrigeration unit22busing a third electrical connection430. The electricity may be split exiting the first DC/AC inverter374into the second electrical connection420and third electrical connection430using a junction point510.

The method900may also provide that a second DC/AC inverter378converts the electricity received from the first DC/DC converter372from DC to AC and conveys the electricity to the second transportation refrigeration unit22b.The second DC/AC inverter378is in a second circuit path490,690and the first DC/AC inverter374is in a first circuit path480,680. The first DC/AC inverter374is configured to convey the electricity to the first transportation refrigeration unit22a.

The method900may yet further provide that the electricity is conveyed from the energy storage device350to the first DC/DC converter372using a first electrical connection410. The electricity is split exiting the first DC/DC converter372into the first DC/AC inverter374and the second DC/AC inverter378using a junction point610.

The method900may also further provide that the electricity is conveyed from the first DC/AC inverter374to the first transportation refrigeration unit22ausing a second electrical connection420and from the second DC/AC inverter378to the second transportation refrigeration unit22busing a third electrical connection430.

The method900may additionally provide that a second DC/DC converter376increases the voltage of the electricity received from the energy storage device350from the first voltage to a third voltage. The third voltage may be equivalent to the second voltage. The second DC/DC converter376is a second circuit path490and the first DC/DC converter372is in a first circuit path480. A second DC/AC inverter378converts the electricity received from the second DC/DC converter376from DC to AC and conveying the electricity to the second transportation refrigeration unit106b.The second DC/AC inverter376is in the second circuit path490and the first DC/AC inverter374is in the first circuit path480. The first DC/AC inverter374is configured to convey the electricity to the first transportation refrigeration unit106a. The electricity is conveyed from the energy storage device350to the first DC/DC converter372and the second DC/DC converter376using a first electrical connection410. A junction point411is configured to split the electricity exiting the energy storage device350into the first DC/DC converter372and the second DC/DC converter376.

While the above description has described the flow process ofFIG.9in a particular order, it should be appreciated that unless otherwise specifically required in the attached claims that the ordering of the steps may be varied.

Referring now toFIG.10, with continued reference toFIGS.4-6.FIG.10shows a flow process illustrating a method1000of assembling a multi-unit transport refrigeration system100, according to an embodiment of the present disclosure.

At block1004, a first transportation refrigeration unit22ais operably connected to a first transport container106a.The first transportation refrigeration unit22aconfigured to refrigerate the first transport container106a.At block1006, a second transportation refrigeration unit22bis operably connected to a second transport container106b.The second transportation refrigeration unit22bconfigured to refrigerate the second transport container106b.At block1008, an energy storage device350is electrically connected to a first DC/DC converter372. The first DC/DC converter372being configured to increase a voltage of the electricity received from the energy storage device350from a first voltage to a second voltage. At block1010, the first DC/DC converter372is electrically connected to the first transportation refrigeration unit22aand the second transportation refrigeration unit22busing at least a first DC/AC inverter374. The first DC/AC inverter374configured to convert the electricity received from the first DC/DC converter372from DC to AC and then convey the electricity to at least one of the first transportation refrigeration unit22aor the second transportation refrigeration unit22b.

The method1000may also include that the energy storage device350is electrically connected to the first DC/DC converter372using a first electrical connection410. The method1000may further include that the first DC/AC inverter374is electrically connected to the first transportation refrigeration unit22ausing a second electrical connection420. The method1000may yet further include that the first DC/AC inverter374is electrically connected to the second transportation refrigeration unit22busing a third electrical connection430and the first DC/AC inverter374is electrically connected to the second electrical connection420and third electrical connection430using a junction point510.

The method1000may also include that the first DC/DC converter372is electrically connected to the first transportation refrigeration unit22aand the second transportation refrigeration unit22busing the first DC/AC inverter374and a second DC/AC inverter378. The second DC/AC inverter378is in a second circuit path490,690and the first DC/AC inverter374is in a first circuit path480,680. The first DC/AC inverter374is configured to convey the electricity to the first transportation refrigeration unit22a.The energy storage device350is electrically connected to the first DC/DC converter372using a first electrical connection410and the first DC/DC converter372is electrically connected to the first DC/AC inverter374and the second DC/AC inverter378using a junction point610. The method1000may yet further provide that the first DC/AC inverter374is electrically connected to the first transportation refrigeration unit22ausing a second electrical connection420and the second DC/AC inverter378is electrically connected to the second transportation refrigeration unit22busing a third electrical connection430.

The method1000may additionally provide that a second DC/DC converter376is electrically connected to the energy storage device350. The second DC/DC converter376increases the voltage of the electricity received from the energy storage device350from the first voltage to a third voltage. The third voltage may be equivalent to the second voltage. The second DC/DC converter376is in the second circuit path490and the first DC/DC converter372is in the first circuit path480. A second DC/AC inverter378converts the electricity received from the second DC/DC converter376from DC to AC and conveying the electricity to the second transportation refrigeration unit106b.The second DC/AC inverter376is in the second circuit path490and the first DC/AC inverter374is in the first circuit path480. The first DC/AC inverter374is configured to convey the electricity to the first transportation refrigeration unit106a.The energy storage device350is electrically connected to the first DC/DC converter372and the second DC/DC converter376using a first electrical connection410. The energy storage device350is electrically connected to the first DC/DC converter372and the second DC/DC converter376using a junction point411.

While the above description has described the flow process ofFIG.10in a particular order, it should be appreciated that unless otherwise specifically required in the attached claims that the ordering of the steps may be varied.

As described above, embodiments can be in the form of processor-implemented processes and devices for practicing those processes, such as processor. Embodiments can also be in the form of computer program code (e.g., computer program product) containing instructions embodied in tangible media, such as floppy diskettes, CD ROMs, hard drives, or any other non-transitory computer readable medium, wherein, when the computer program code is loaded into and executed by a computer, the computer becomes a device for practicing the embodiments. Embodiments can also be in the form of computer program code, for example, whether stored in a storage medium, loaded into and/or executed by a computer, or transmitted over some transmission medium, loaded into and/or executed by a computer, or transmitted over some transmission medium, such as over electrical wiring or cabling, through fiber optics, or via electromagnetic radiation, wherein, when the computer program code is loaded into an executed by a computer, the computer becomes an device for practicing the exemplary embodiments. When implemented on a general-purpose microprocessor, the computer program code segments configure the microprocessor to create specific logic circuits.