Patent Description:
Trailers are used to transport goods. Trailers typically have a rectangular shape and an empty interior that can be filled with various types of perishable and non-perishable goods. In some cases, those goods need to be maintained at a certain controlled temperature and in these cases, trailers can include refrigeration units, such as TRUs. A TRU for a trailer can cool or condition the air inside of the trailer so that the goods being transported can be refrigerated.

In conventional TRUs, energy to operate the TRU can be provided by fuel or batteries. More recently, fuel cells that use hydrogen to generate energy have been employed. <CIT> discloses a transport refrigeration unit including a combustion engine of the unit driving a generator configured to provide electric power to a compressor motor. An energy storage device of the unit is configured to provide electric power to the condenser and evaporator fan motors. <CIT> discloses methods and systems for controlling energy source for a mild hybrid system that powers a transport climate control system are provided. The mild hybrid system includes a DC energy source configured to supply a first DC voltage to the transport climate control system. Other electrical component controls of trucks and/or refrigeration systems are disclosed in <CIT>, <CIT> and <CIT>.

According to a first aspect of the invention defined in claim <NUM>, 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 powered by the high-voltage power source, a second electrical load, which is powered by the low-voltage power source and 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. The system comprises 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, wherein the high-voltage power source and the low-voltage power source each comprise a fuel cell and the TRU system further comprises a tank storing cryo-compressed hydrogen gas for the high-voltage power source and the low-voltage power source.

The high-voltage power source may include a battery.

The high-voltage power source may be plural in number.

The low-voltage power source may include a battery.

The low-voltage power source may be plural in number.

The first electrical load may include at least a compressor motor.

The second electrical load may include at least one or more of an evaporator fan motor and a condenser fan motor.

At least the first electrical load may be controllable for optimized load operation.

The voltage conversion unit may be selectively engageable to allow for dynamic power allocation to at least one of the first electrical load and the second electrical load.

The voltage conversion unit may be selectively engageable for redundancy in an event of a fault in either the high-voltage power source or the low-voltage power source.

According to another aspect of the invention defined in claim <NUM>, a method of operating a transport refrigeration unit (TRU) system according to the first aspect (optionally in combination with any of the optional features thereof) is provided and includes 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.

The selectively engaging of the voltage conversion unit may include 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.

The subject matter, which is regarded as the invention, is defined in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention are apparent from the following detailed description. Certain exemplary embodiments will now be described in greater detail, by way of example only, and with reference to the accompanying drawings, in which:.

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.

With reference to <FIG>, a tractor trailer system <NUM> is provided. The tractor trailer system <NUM> includes a tractor <NUM> including an operator's compartment or cab <NUM> and an engine, which acts as the drive system of the tractor trailer system <NUM>. A trailer <NUM> is coupled to the tractor <NUM>. The trailer <NUM> is a refrigerated trailer <NUM> and includes a top wall <NUM>, a directly opposed bottom wall <NUM>, opposed side walls <NUM> and a front wall <NUM>, with the front wall <NUM> being closest to the tractor <NUM>. The trailer <NUM> further includes a door or doors (not shown) at a rear wall <NUM>, opposite the front wall <NUM>. The walls of the trailer <NUM> define a cargo compartment. The trailer <NUM> is configured to maintain a cargo <NUM> located inside the cargo compartment at a selected temperature through the use of a TRU <NUM> located on the trailer <NUM>. The TRU <NUM>, as shown in <FIG>, can be located at or attached to the front wall <NUM>. 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.).

With reference to <FIG>, the TRU <NUM> is shown in more detail. The TRU unit <NUM> includes a compressor <NUM>, a condenser <NUM> with a condenser fan <NUM>, an expansion valve <NUM>, an evaporator <NUM> and an evaporator fan <NUM>. The compressor <NUM> is operably connected to a compressor motor <NUM><NUM>, which is receptive of power and uses that power to drive the compressor <NUM>. The evaporator fan <NUM> is operably connected to an evaporator fan motor <NUM><NUM>, which is receptive of power and uses that power to drive the evaporator fan <NUM>. The condenser fan <NUM> is operably connected to a condenser fan motor <NUM><NUM>, which is receptive of power and uses that power to drive the condenser fan <NUM>. Airflow is circulated into and through the cargo compartment of the trailer <NUM> by means of the TRU <NUM>. A return airflow <NUM> flows into the TRU <NUM> from the cargo compartment of the trailer <NUM> through a refrigeration unit inlet <NUM> and across the evaporator <NUM> via the evaporator fan <NUM>, thus cooling the return airflow <NUM>. The cooled return airflow <NUM>, now referred to as supply airflow <NUM>, is supplied into the cargo compartment of the trailer <NUM> through a refrigeration unit outlet <NUM>, which in some embodiments is located near the top wall <NUM> of the trailer <NUM>. The supply airflow <NUM> cools the cargo <NUM> in the cargo compartment of the trailer <NUM>. Also included in the cargo compartment can be a refrigerant leak sensor <NUM> for detecting a leak of a particular type of refrigerant or substance. It is to be understood that the refrigerant leak sensor <NUM> can be located in different locations in the system and is not limited by the example shown in <FIG>. For example, the refrigerant leak sensor <NUM> can be located in the evaporator section of the TRU <NUM>, a different portion of the cargo compartment of the trailer <NUM> or another location in the system. Upon detection by the refrigerant leak sensor <NUM>, a signal can be transmitted to controller <NUM>. The controller <NUM> controls various aspects of the TRU <NUM> and the TRU power system. The controller <NUM> can control the compressor <NUM>, the condenser <NUM>, the expansion valve <NUM>, the evaporator <NUM> and the evaporator fan <NUM> in addiction to other equipment or sensors. The controller <NUM> can be connected to the equipment over a wired or wireless connection (connections not shown). In some cases, the controller <NUM> can be configured to perform a low charge diagnostics calculation which is used to perform various calculations of the refrigeration system of the TRU <NUM> 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>).

With reference to <FIG> and <FIG>, the TRU system <NUM> includes a high-voltage power source <NUM>, a low-voltage power source <NUM>, a first electrical load <NUM>, which is powered by the high-voltage power source <NUM> and a second electrical load <NUM>, which is powered by the low-voltage power source <NUM>. The TRU system <NUM> further includes an electrical distribution system <NUM>. The electrical distribution system <NUM> includes at least a first electrical linkage <NUM> by which the high-voltage power source <NUM> is directly electrically connected to the first electrical load <NUM> and at least a second electrical linkage <NUM> by which the low-voltage power source <NUM> is directly electrically connected to the second electrical load <NUM>.

The high-voltage power source <NUM> can provide power greater than <NUM> V (e.g., <NUM>-80V) and comprises a fuel cell. The low-voltage power source <NUM> can provide power of less than 50V, with a nominal output of about 48V, and comprises a fuel cell. Hydrogen for the fuel cells (i.e., cryo-compressed hydrogen gas) for the high-voltage power source <NUM> and the low-voltage power source <NUM> is stored in a tank <NUM> (e.g., below the trailer <NUM> as shown in <FIG>).

In some alternative embodiments, the high-voltage power source <NUM> can further include a battery and can be plural in number (i.e., there can be multiple high-voltage power sources <NUM>, each being either a fuel cell or a battery but with at least one fuel cell). Similarly, in some other alternative embodiments, the low-voltage power source <NUM> can further include a battery and can be plural in number (i.e., there can be multiple low-voltage power sources <NUM>, each being either a fuel cell or a battery but with at least one fuel cell). In the case of either the high-voltage power source <NUM> or the low-voltage power source <NUM> 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 <NUM> of <FIG>).

In those cases where the high-voltage power source <NUM> or the low-voltage power source <NUM> is provided as a battery, the TRU system <NUM> 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.

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

In accordance with embodiments, the second electrical load <NUM> 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 <NUM><NUM> and the condenser fan motor <NUM><NUM> of <FIG>, which may be optimally powered by the low-voltage power source <NUM>, as well as other low-voltage loads. As above, in these or other cases, fixed or variable speed motor drives <NUM> can be electrically interposed between the low-voltage power source <NUM> and the evaporator fan motor <NUM><NUM> and the condenser fan motor <NUM><NUM>. In addition, a power conversion unit <NUM> can be electrically interposed between the low-voltage power source <NUM> and the other low-voltage loads. In an exemplary case, the fixed or variable speed motor drive <NUM> can provide compatibility between the low-voltage power source <NUM> and the evaporator fan motor <NUM><NUM> and the condenser fan motor <NUM><NUM>.

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

A shown in <FIG>, the TRU system <NUM> includes a voltage conversion unit <NUM>.

The voltage conversion unit <NUM> is electrically interposed between the first electrical linkage <NUM> and the second electrical linkage <NUM>. The voltage conversion unit <NUM> is selectively engageable so that the high-voltage power source <NUM> can be selectively electrically connectable to the second electrical load <NUM> and so that the low-voltage power source <NUM> can be selectively electrically connectable to the first electrical load <NUM>. As such, the voltage conversion unit <NUM> is selectively engageable to allow for dynamic power allocation to at least one of the first electrical load <NUM> and the second electrical load <NUM>. That is, in the exemplary case where the first electrical load <NUM> is the compressor motor <NUM><NUM> of <FIG> and is being controlled for optimized load operation, the voltage conversion unit <NUM> can be selectively engaged to connect the low-voltage power source to the compressor motor <NUM><NUM> 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 <NUM> and the compressor motor <NUM><NUM> may be maintained though the high-voltage power source <NUM> may be otherwise prevented from providing power to the compressor motor <NUM><NUM>. In addition, the voltage conversion unit <NUM> can be selectively engageable for redundancy in an event of a fault in either the high-voltage power source <NUM> or the low-voltage power source <NUM> which prevents the faulty power source from providing power to an electrical load for which it would otherwise provide power.

With reference to <FIG>, a method <NUM> of operating TRU system, such as the TRU system <NUM> of <FIG> and <FIG>, is provided. The method <NUM> includes directly electrically connecting a high-voltage power source to a first electrical load, which is powered by the high-voltage power source (block <NUM>), directly electrically connecting a low-voltage power source to a second electrical load, which is powered by the low-voltage power source (block <NUM>) 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 <NUM>). In accordance with embodiments, the selectively engaging of the voltage conversion unit of block <NUM> 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 <NUM>) 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 <NUM>).

Technical effects and benefits of the present invention 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.

Claim 1:
A transport refrigeration unit (TRU) system (<NUM>), comprising:
a high-voltage power source (<NUM>);
a low-voltage power source (<NUM>), at least one of the high-voltage power source (<NUM>) and the low-voltage power source (<NUM>) comprising a fuel cell configured to provide electricity to the transport refrigeration unit (<NUM>);
a first electrical load (<NUM>), which is powered by the high-voltage power source (<NUM>);
a second electrical load (<NUM>), which is powered by the low-voltage power source (<NUM>); and
an electrical distribution system (<NUM>) comprising a first linkage (<NUM>) by which the high-voltage power source (<NUM>) is directly electrically connected to the first electrical load (<NUM>) and a second linkage by which the low-voltage power source (<NUM>) is directly electrically connected to the second electrical load (<NUM>); and
a voltage conversion unit (<NUM>) electrically interposed between the first and second linkages (<NUM>, <NUM>) and by which the high-voltage power source (<NUM>) is selectively electrically connectable to the second electrical load (<NUM>) and the low-voltage power source (<NUM>) is selectively electrically connectable to the first electrical load (<NUM>),
characterised in that the high-voltage power source (<NUM>) and the low-voltage power source (<NUM>) each comprise a fuel cell and the TRU system further comprises a tank storing cryo-compressed hydrogen gas for the high-voltage power source (<NUM>) and the low-voltage power source (<NUM>).