Patent Description:
Traditional refrigerated cargo trucks or refrigerated tractor trailers, such as those utilized to transport cargo via sea, rail, or road, is a truck, trailer or cargo container, generally defining a cargo compartment, and modified to include a refrigeration system located at one end of the truck, trailer, or cargo container. Refrigeration systems typically include a compressor, a condenser, an expansion valve, and an evaporator serially connected by refrigerant lines in a closed refrigerant circuit in accord with known refrigerant vapor compression cycles. A power unit, such as a combustion engine, drives the compressor of the refrigeration unit, and may be diesel powered, natural gas powered, or other type of engine. In many tractor trailer transport refrigeration systems, the compressor is driven by the engine shaft either through a belt drive or by a mechanical shaft-to-shaft link. In other systems, the engine of the refrigeration unit drives a generator that generates electrical power, which inturn drives the compressor.

With current environmental trends, improvements in transportation refrigeration units are desirable particularly toward aspects of efficiency, sound and environmental impact. With environmentally friendly refrigeration units, improvements in reliability, cost, and weight reduction is also desirable.

<CIT> discloses hybrid power systems which include an internal combustion engine and a motor/generator connectable with the engine. A reefer unit is configured to receive power from the motor/generator via a reefer power system that includes an export power inverter and an energy storage device. <CIT> discloses a refrigerator-freezer capable of improving cooling performance by effectively utilizing available power in the refrigerator-freezer of which refrigerators installed side by side is cooled by circulating cold from a heat exchanger inside a freezer. An electric fan is stopped when the cooling of the inside of a freezer A is necessary and the cooling of the inside of a refrigerator B is not necessary, and surplus power generated by the stop of the electric fan is fed to an electric fan. The power fed to an electric fan can be decreased and the power fed to either or both of the electric fans can be increased according to the amount of the decreased power.

According to as first aspect, the invention provides a power system architecture configured to power a transport refrigeration system based on a determined an AC power requirement. The system includes a generator power converter configured to receive a generator three phase AC power from an alternating current (AC) generator operably coupled to an axle or wheel hub, and provide a generator DC power. The system also includes a grid power converter configured to receive a grid three phase AC power from a grid power source, the grid power converter operable to provide a grid DC power, an energy storage device, the energy storage device operable to provide a variable DC power and connected to a DC bus, a power management system operably connected to direct power the transport refrigeration unit TRU based on at least the AC power requirement, and a DC/DC converter operably connected to a variable DC bus, the DC/DC converter configured to convert a DC power to a fixed DC power on a fixed DC bus. The energy storage system includes the energy storage device and at least one of a first energy storage system DC/DC converter configured to convert the variable DC power on the variable DC bus to a fixed DC power on a fixed DC bus to provide the fixed DC power to the power management system based at least in part on the AC power requirement and a second energy storage system DC/DC converter configured to convert at least a portion of the fixed DC power on the fixed DC bus to supply the variable DC bus and the energy storage device.

Optionally, the generator power converter is configured to receive a first three phase AC power provided by the AC generator and transmit the generator DC power to one of the fixed DC bus or the variable DC bus.

Optionally, the generator power converter includes an AC/DC converter and the generator three phase AC power exhibits a first AC voltage and a first AC current, at a first frequency, and the generator DC power exhibits a second DC voltage and a second DC current.

Optionally, the generator power converter includes a voltage control function, and a current control function, wherein at least the voltage control function is responsive at least in part to the AC power requirement.

Optionally, the grid power converter is configured to receive a first three phase AC power provided by the grid power source and transmit the grid DC power to one of the fixed DC bus or the variable DC bus.

Optionally, the grid power converter includes an AC/DC converter and the grid three phase AC power exhibits a grid AC voltage and a grid AC current, at a grid frequency, and the grid DC power exhibits a grid DC voltage and a grid DC current.

Optionally, the grid power converter includes a voltage control function, and a current control function, wherein at least the voltage control function is responsive at least in part to the AC power requirement.

Optionally, embodiments may include a battery management system operably connected to the TRU controller and configured to monitor at least a state of charge of the energy storage device.

Optionally, embodiments may include that the energy storage system DC/DC converter and the second energy storage system DC/DC converter are integrated.

Optionally, the energy storage device comprises at least one of a battery, fuel cell, and flow battery.

Optionally, the power management system is configured to receive the fixed DC power from the fixed DC bus, and to provide a second three phase AC power to the TRU based at least on the AC power requirement.

Optionally, the power management system includes a DC/AC converter and the second three phase AC power exhibits a second three phase AC voltage and a second AC current, at a second frequency.

Optionally, the grid power converter, generator power converter, energy storage device, and power management system are operably connected to the variable DC bus.

Optionally, the grid power converter, generator power converter, the power management system, and energy storage system DC/DC converter are operably connected to the fixed DC bus, and the energy storage system DC/DC converter and energy storage device are operably connected to the variable DC bus.

Optionally, the grid power converter and power management system and energy storage system DC/DC converter are connected to the fixed DC bus, and the energy storage system DC/DC converter and generator power converter and energy storage device are operably connected to the variable DC bus.

Optionally, the grid power converter, the generator power converter, energy storage system DC/DC converter and energy storage device are connected to the variable DC bus, and the energy storage system DC/DC converter and the power management system are operably connected to the fixed DC bus.

Optionally, the grid power converter, power management system, the energy storage system DC/DC converter, and energy storage device are connected to the variable DC bus, and the energy storage system DC/DC converter and the generator power converter are operably connected to the fixed DC bus.

Optionally, the grid power converter, the generator power converter, the energy storage system DC/DC converter are connected to the fixed DC bus, and the energy storage system DC/DC converter and the energy storage device are operably connected to the variable DC bus.

Optionally, the grid power converter, and the energy storage system DC/DC converter are connected to the fixed DC bus, and the energy storage system DC/DC converter, the generator power converter and the energy storage device are operably connected to the variable DC bus.

Optionally, the generator power converter and power management system and energy storage system DC/DC converter are connected to the fixed DC bus, and the energy storage system DC/DC converter and grid power converter and energy storage device are operably connected to the variable DC bus.

Optionally, embodiments may include a return air temperature (RAT) sensor disposed in the return airflow and configured measure the temperature of the return airflow, the RAT sensor operably connected to the TRU controller, the TRU controller configured to execute a process to determine the AC power requirement for the TRU based at least in part on the RAT.

Technical effects of embodiments of the present disclosure include a transportation refrigeration unit coupled to and powered by an external generator system via a generator power converter, where the power generated by the generator and converted by the generator power converter is based on an AC power requirement of the transportation refrigeration unit.

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.

Referring to <FIG>, a transport refrigeration system <NUM> is illustrated. In the illustrated embodiment, the transport refrigeration systems <NUM> may include a tractor or vehicle <NUM>, a container <NUM>, and an engineless transportation refrigeration unit (TRU) <NUM>. The container <NUM> may be pulled by a vehicle <NUM>. It is understood that embodiments described herein may be applied to shipping containers that are shipped by rail, sea, air, or any other suitable container, thus the vehicle may be a truck, train, boat, airplane, helicopter, etc..

The vehicle <NUM> may include an operator's compartment or cab <NUM> and a combustion engine <NUM> which is part of the powertrain or drive system of the vehicle <NUM>. In some instances, the vehicle <NUM> may be a hybrid or all electric configuration having electric motors to provide propulsive force for the vehicle. In some configurations, the TRU system <NUM> may be engineless. A small engine or the engine of the vehicle <NUM> may be employed to power or partially power the TRU <NUM>. The container <NUM> may be coupled to the vehicle <NUM> and is thus pulled or propelled to desired destinations. The trailer may include a top wall <NUM>, a bottom wall <NUM> opposed to and spaced from the top wall <NUM>, two side walls <NUM> spaced from and opposed to one-another, and opposing front and rear walls <NUM>, <NUM> with the front wall <NUM> being closest to the vehicle <NUM>. The container <NUM> may further include doors (not shown) at the rear wall <NUM>, or any other wall. The walls <NUM>, <NUM>, <NUM>, <NUM>, <NUM> together define the boundaries of a cargo compartment <NUM>. Typically, transport refrigeration systems <NUM> are used to transport and distribute cargo, such as, for example perishable goods and environmentally sensitive goods (herein referred to as perishable goods). The perishable goods may 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 cold chain transport. In the illustrated embodiment, the TRU <NUM> is associated with a container <NUM> to provide desired environmental parameters, such as, for example temperature, pressure, humidity, carbon dioxide, ethylene, ozone, light exposure, vibration exposure, and other conditions to the cargo compartment <NUM>. In further embodiments, the TRU <NUM> is a refrigeration system capable of providing a desired temperature and humidity range.

Referring to <FIG> and <FIG>, the container <NUM> is generally constructed to store a cargo (not shown) in the compartment <NUM>. The engineless TRU <NUM> is generally integrated into the container <NUM> and may be mounted to the front wall <NUM>. The cargo is maintained at a desired temperature by cooling of the compartment <NUM> via the TRU <NUM> that circulates refrigerated airflow into and through the cargo compartment <NUM> of the container <NUM>. It is further contemplated and understood that the TRU <NUM> may be applied to any transport compartments (e.g., shipping or transport containers) and not necessarily those used in tractor trailer systems. Furthermore, the transport container <NUM> may be a part of the of the vehicle <NUM> or constructed to be removed from a framework and wheels (not shown) of the container <NUM> for alternative shipping means (e.g., marine, railroad, flight, and others).

The components of the engineless TRU <NUM> include a compressor <NUM>, evaporator <NUM>, an evaporator fan assembly <NUM> and a controller <NUM>, and may further include an electric compressor motor <NUM>, a condenser <NUM> that may be air cooled, a condenser fan assembly <NUM>, a receiver <NUM>, a filter dryer <NUM>, a heat exchanger <NUM>, an expansion valve <NUM>, a suction modulation valve <NUM>, and that may include a computer-based processor (e.g., microprocessor) and the like as will be described further herein. Operation of the engineless TRU <NUM> may best be understood by starting at the compressor <NUM>, where the suction gas (e.g., natural refrigerant, hydrofluorocarbon (HFC) R-404a, HFC R-134a. etc.) enters the compressor <NUM> at a suction port <NUM> and is compressed to a higher temperature and pressure. The refrigerant gas is emitted from the compressor <NUM> at an outlet port <NUM> and may then flow into tube(s) <NUM> of the condenser <NUM>.

Air flowing across a plurality of condenser coil fins (not shown) and the tubes <NUM>, cools the gas to its saturation temperature. The air flow across the condenser <NUM> may be facilitated by one or more fans <NUM> of the condenser fan assembly <NUM>. The condenser fans <NUM> may be driven by respective condenser fan motors <NUM> of the fan assembly <NUM> that may be electric. By removing latent heat, the refrigerant gas within the tubes <NUM> condenses to a high pressure and high temperature liquid and flows to the receiver <NUM> that provides storage for excess liquid refrigerant during low temperature operation. From the receiver <NUM>, the liquid refrigerant may pass through a sub-cooler heat exchanger <NUM> of the condenser <NUM>, through the filter-dryer <NUM> that keeps the refrigerant clean and dry, then to the heat exchanger <NUM> that increases the refrigerant sub-cooling, and finally to the expansion valve <NUM>.

As the liquid refrigerant passes through the orifices of the expansion valve <NUM>, some of the liquid vaporizes into a gas (i.e., flash gas). Return air from the refrigerated space (i.e., cargo compartment <NUM>) flows over the heat transfer surface of the evaporator <NUM>. As the refrigerant flows through a plurality of tubes <NUM> of the evaporator <NUM>, the remaining liquid refrigerant absorbs heat from the return air, and in so doing, is vaporized and thereby cools the return air.

The evaporator fan assembly <NUM> includes one or more evaporator fans <NUM> that may be driven by respective fan motors <NUM> that may be electric. The air flow across the evaporator <NUM> is facilitated by the evaporator fans <NUM>. From the evaporator <NUM>, the refrigerant, in vapor form, may then flow through the suction modulation valve <NUM>, and back to the compressor <NUM>. The expansion valve <NUM> may be thermostatic or electrically adjustable. In an embodiment, as depicted, the expansion valve <NUM> is thermostatic. A thermostatic expansion valve bulb sensor <NUM> may be located proximate to an outlet of the evaporator tube <NUM>. The bulb sensor <NUM> is intended to control the thermostatic expansion valve <NUM>, thereby controlling refrigerant superheat at an outlet of the evaporator tube <NUM>. It is further contemplated and understood that the above generally describes a single stage vapor compression system that may be used for HFCs such as R-404a and R-134a and natural refrigerants such as propane and ammonia. Other refrigerant systems may also be applied that use carbon dioxide (CO<NUM>) refrigerant, and that may be a two-stage vapor compression system. In another embodiment, the expansion valve <NUM> could be an electronic expansion valve. In this case the expansion valve is commanded to a selected position by the controller <NUM> based on the operating conditions of the vapor compression cycle and the demands of the system.

A bypass valve (not shown) may facilitate the flash gas of the refrigerant to bypass the evaporator <NUM>. This will allow the evaporator coil to be filled with liquid and completely 'wetted' to improve heat transfer efficiency. With CO<NUM> refrigerant, this bypass flash gas may be re-introduced into a mid-stage of a two-stage compressor <NUM>.

The compressor <NUM> and the compressor motor <NUM> may be linked via an interconnecting drive shaft <NUM>. The compressor <NUM>, the compressor motor <NUM> and the drive shaft <NUM> may all be sealed within a common housing <NUM>. The compressor <NUM> may be a single compressor. The single compressor may be a two-stage compressor, a scroll-type compressor or other compressors adapted to compress HFCs or natural refrigerants. The natural refrigerant may be CO<NUM>, propane, ammonia, or any other natural refrigerant that may include a global-warming potential (GWP) of about one (<NUM>).

Continuing with <FIG>, and with continued reference to <FIG>, <FIG> also illustrates airflow through the TRU <NUM> and the cargo compartment <NUM>. Airflow is circulated into and through and out of the cargo compartment <NUM> of the container <NUM> by means of the TRU <NUM>. A return airflow <NUM> flows into the TRU <NUM> from the cargo compartment <NUM> through a return air intake <NUM>, and across the evaporator <NUM> via the fan <NUM>, thus conditioning the return airflow <NUM> to a selected or predetermined temperature. The conditioned return airflow <NUM>, now referred to as supply airflow <NUM>, is supplied into the cargo compartment <NUM> of the container <NUM> through the refrigeration unit outlet <NUM>, which in some embodiments is located near the top wall <NUM> of the container <NUM>. The supply airflow <NUM> cools the perishable goods in the cargo compartment <NUM> of the container <NUM>. It is to be appreciated that the TRU <NUM> can further be operated in reverse to warm the container <NUM> when, for example, the outside temperature is very low.

A temperature sensor <NUM> (i.e., thermistor, thermocouples, RTD, and the like) is placed in the air stream, on the evaporator <NUM>, at the return air intake <NUM> , and the like, to monitor the temperature return airflow <NUM> from the cargo compartment <NUM>. A sensor signal indicative of the return airflow temperature denoted RAT is operably connected via line <NUM> to the TRU controller <NUM> to facilitate control and operation of the TRU <NUM>. Likewise, a temperature sensor <NUM> is placed in the supply airflow <NUM>, on the evaporator <NUM>, at the refrigeration unit outlet <NUM> to monitor the temperature of the supply airflow <NUM> directed into the cargo compartment <NUM>. Likewise, a sensor signal indicative of the supply airflow temperature denoted SAT <NUM> is operably connected via line <NUM> to the TRU controller <NUM> to facilitate control and operation of the TRU <NUM>.

Referring now to <FIG>, with continued reference to <FIG> and <FIG> as well, the TRU <NUM> may include or be operably interfaced with a power supply interface shown generally as <NUM>. The power supply interface <NUM> may include, interfaces to/from various power sources denoted generally as <NUM> and more specifically as follows herein as well as one or more DC busses shown generally as <NUM> and more specifically 125a, 125b,. In an embodiment, the power sources <NUM> may include, but not be limited to an energy storage device <NUM>, generator <NUM>, and grid power, <NUM>. Each of the power sources <NUM> may be configured to selectively power the TRU <NUM> as described further herein, including compressor motor <NUM>, the condenser fan motors <NUM>, the evaporator fan motors <NUM>, the controller <NUM>, and other components <NUM> of the TRU <NUM> that may include various solenoids and/or sensors). The controller <NUM> through a series of data and command signals over various pathways <NUM> may, for example, control the application of power to the electric motors <NUM>, <NUM>, <NUM> as dictated by the cooling needs of the TRU <NUM>.

The engineless TRU <NUM> may include an AC or DC architecture with selected components employing alternating current (AC), and others employing direct current (DC). For example, in an embodiment, the motors <NUM>, <NUM>, <NUM> may be configured as AC motors, while in other embodiments, the motors <NUM>, <NUM>, <NUM> may be configured as DC motors. The operation of the of the power sources <NUM> as they supply power to the TRU <NUM> is managed and monitored by the TRU controller <NUM> and interfaced from the DC bus <NUM> to the power management system <NUM>. The power management system <NUM> is configured direct the power from the various power sources <NUM>, and the like, via DC bus <NUM> based on various requirements of the TRU <NUM>. In an embodiment, the TRU controller <NUM> receives various signals indicative of the operational state of the TRU <NUM> and determines the power requirements for the TRU system <NUM> accordingly and directs the components of the power supply interface <NUM> and specifically the power management system <NUM> to direct power accordingly to address the requirements of the TRU <NUM>.

In one embodiment, the TRU system <NUM> is controlled to a temperature setpoint value selected by the user. The TRU controller <NUM> monitors the RAT and optionally the SAT as measured by the temperature sensors <NUM> and <NUM> respectively. The TRU controller <NUM> estimates the power requirements for the TRU <NUM> based on the RAT (among others) and provides commands accordingly to the various components of the power supply interface <NUM> and specifically the power management system <NUM>, energy storage system <NUM>, and generator power converter <NUM> to manage the generation, conversion, and routing of power in the power supply interface <NUM> and TRU system <NUM>. By using the measured RAT and the setpoint value, an estimate to power demand is made. More specifically, in one embodiment, if the (RAT-setpoint value) is above a first threshold (e.g., > <NUM> degrees F), then full power (e.g., at a known voltage supply, current demand is known) is needed by the TRU system <NUM>. If the (RAT-setpoint value) is between first threshold and second threshold, current requirement is limited (at known voltage) to achieve a mid-range power (e.g., -<NUM>% power or something less than <NUM>%). If the (RAT-setpoint value) is below second threshold, current is limited (at voltage) to achieve a minimum power (e.g., -<NUM>% power).

The TRU controller <NUM> is configured to control the components in the TRU <NUM> as well as the components of the power supply interface <NUM> in accordance with operating needs of the transport refrigeration system <NUM>. The TRU controller <NUM> is communicatively coupled to the power management system <NUM>, the grid power source <NUM>, the energy storage system <NUM>, and the generator power converter <NUM> or generator <NUM>. For the TRU power demand, the TRU controller <NUM>, using additional information from each of the power sources <NUM> provides instructions to affect the grid power source <NUM> output, the generator <NUM> and generator power converter <NUM> output, the charge/discharge of the energy storage system <NUM>, all to enable and configure providing power as required by the TRU <NUM>. Additionally, the TRU controller <NUM> provides instructions for various components in the power supply interface <NUM> to manage the power flow to the DC Bus <NUM> and thereby to the power management system <NUM> depending upon the operational status of the various power sources (i.e. grid power <NUM>, energy storage device <NUM> and generator <NUM>) and as based on the TRU <NUM> power demand.

In an embodiment, the power management system <NUM> includes a DC/AC converter <NUM>. The DC/AC converter <NUM> is configured to receive DC power on the DC bus <NUM> denoted in this instance 125a (e.g., second DC voltage V<NUM>, a second DC current I<NUM> from the generator power converter <NUM>; and/or VG, IG <NUM>; and/or DC voltage <NUM> from the energy storage device <NUM>; alone or as combined) and generate three phase AC power <NUM> (e.g., at AC voltage V<NUM>, AC current I<NUM> a frequency f<NUM>), for providing power to the TRU system <NUM>. In an embodiment, the DC/AC converter <NUM> includes a voltage control function, a current control function, and a frequency control function, each configured to facilitate the conversion. In an embodiment, the TRU controller <NUM> provides command signals denoted by line <NUM>, to the power management system <NUM>. The commands are based, at least, on the power consumption requirements of the TRU <NUM> as discussed further herein. In addition, the TRU controller <NUM> may receive status information also depicted by line <NUM> regarding the DC/AC converter <NUM>. In an embodiment, the communications may be over standard communication interfaces such as CAN, RS-<NUM>, and the like. Moreover, as is discussed further herein, the communications may be wired or wireless.

As described further herein, there are three power sources <NUM> grid power <NUM>, generator <NUM>/generator power converter <NUM> and energy storage device <NUM>. If the TRU <NUM> is "On" and operating, the TRU controller <NUM> knows, the power requirements for the TRU system <NUM>, and thereby, what power is needed. The TRU controller <NUM> is also programmed to ascertain whether or not grid power (e.g., <NUM>) is available or not. If the grid power is available and TRU is On and energy storage device <NUM> (e.g., battery) SOC indicates a full charge, grid power will satisfy TRU system <NUM> power demand. Conversely, if grid power <NUM> is available and TRU On and the energy storage device is not fully charged, TRU power demand is satisfied as first priority and then DC/DC converter <NUM> is be activated to provide necessary charging to energy storage device <NUM> as second priority. Moreover, if grid power <NUM> is available and TRU is "Off' and the energy storage device <NUM> is not fully charged, the DC/DC converter156 will be activated to provide necessary charging current. If grid power <NUM> is not available and generator/generator power converter <NUM>/<NUM> is not operable, all TRU power demand is satisfied by the energy storage system <NUM> via the energy storage device <NUM>. Finally, if grid power <NUM> is not available and generator/generator power converter <NUM>/<NUM> is operable, then TRU power demand is satisfied by both the generator <NUM> & energy storage system <NUM>.

As described herein, in operation, the TRU controller <NUM> identifies the power requirements for the TRU <NUM> at least partially based on the RAT. The TRU controller <NUM> conveys the power requirements to the power management system <NUM> and/or the generator power converter <NUM> to convert the first three phase AC power <NUM> or first DC power 163a to the second DC power <NUM> as necessary to satisfy the requirements of the TRU <NUM> and the energy storage system <NUM> and specifically the charging requirements of the energy storage device <NUM>.

The DC bus <NUM> and thereby, the power management system <NUM> may receive power from a grid power source <NUM> when it is available. In an embodiment the grid power source <NUM> is interfaced to the DC bus <NUM> and the power management system <NUM> via a grid power converter <NUM>. In an embodiment, the power management system <NUM> may be a stand-alone unit, or integral with the TRU <NUM>. The grid power source <NUM> is generally conventional three phase AC power <NUM>/480VAC at <NUM> or <NUM>. In an embodiment, the grid power converter <NUM> is a conventional AC/DC converter operable to convert the three phase AC power from the grid power source <NUM> to a DC voltage and current. The grid power converter <NUM> in one or more embodiments generates a grid DC power <NUM> including DC voltage VG, and DC current IG. The grid DC power <NUM> and is transmitted from the grid power converter <NUM> to the DC bus <NUM> and the power management system <NUM> or otherwise as described herein.

The DC bus <NUM> and power management system <NUM> receives power from a generator <NUM> via a generator power converter <NUM>. The generator <NUM> is axle or hub mounted configured to recover rotational energy when the transport refrigeration system <NUM> is in motion and convert that rotational energy to electrical energy, such as, for example, when the axle of the vehicle <NUM> is rotating due to acceleration, cruising, or braking. In an embodiment, the generator <NUM> is configured to provide a first three phase AC power <NUM> comprising voltage V<NUM>, an AC current I<NUM> at a given frequency fi denoted by reference numeral <NUM>. The generator <NUM> may be asynchronous or synchronous.

Continuing with <FIG> and the architecture of the power supply interface <NUM> and the various power sources <NUM> employed to power the TRU <NUM> and the components thereof. In an embodiment, one of the power sources <NUM> includes an energy storage system <NUM> operably coupled to the power management system <NUM>. The energy storage system <NUM> transmits DC power <NUM> via DC bus 125b to, and receives DC power <NUM> from the DC bus <NUM>. The energy storage system <NUM> includes the energy storage device <NUM>, and may include a battery management system <NUM>. In an embodiment, the battery management system <NUM> is a part of, and integral with, the energy storage device <NUM>. In this embodiment DC bus 125a and 125b are directly connected.

In an embodiment the DC voltages from the power sources <NUM> including DC voltage <NUM> from the grid power source <NUM> and/or DC voltage V<NUM>, I<NUM> <NUM> from the generator power converter <NUM> combines to form the DC voltage on the and current on bus 125a, 125b which is directly coupled to the energy storage device <NUM> to the to charge and store energy on the energy storage device <NUM>. Conversely, in other embodiments, for example when grid power source <NUM> is not available, the energy storage device <NUM> supplies DC voltage and current <NUM> directly to the DC bus 125b,125a and the power management system <NUM> for powering the TRU <NUM>. In another embodiment, the energy storage system <NUM> further includes a DC/DC converter <NUM>. In one embodiment, the DC bus <NUM>, and more specifically 125a provides DC power <NUM> to a DC/DC converter <NUM> to formulate a DC voltage and current <NUM> on DC bus 125b to charge and store energy on the energy storage device <NUM>. Conversely, in other embodiments the energy storage device <NUM> supplies DC voltage and current <NUM> via DC bus 125b to the DC/DC converter <NUM> operating as a DC/DC converter to supply a DC power <NUM> to the DC bus <NUM>, 125a, and the power management system <NUM> for powering the TRU <NUM>. It should be appreciated that as described herein, the DC/DC converter <NUM> is bidirectional, enabling conversions in both directions to facilitate charging and discharging the energy storage device <NUM>. While the DC/DC converter <NUM> is described as bidirectional, such description is merely for the purposes of illustration. In operation, the DC/DC converter <NUM> may be a single integrated unit, or multiple units configured in parallel to operate in opposite directions. It is also noteworthy to appreciate that in the various embodiments described herein, numerous architectures are described based on the interconnection between the various power sources <NUM>. More specifically, the interconnection between power sources <NUM>, e.g., grid power source <NUM>, generator <NUM> and the DC/AC converter <NUM> of the power management system <NUM> with the energy storage device <NUM>, based on the optional application of the optional DC/DC converter <NUM>. In the various architectures, where the energy storage device <NUM> is directly connected (e.g. 125a directly connected to 125b), that portion of the bus is termed variable as the voltage is capable of variation based on the state of charge of the energy storage device <NUM>. On the other hand, in the instances where the DC/DC converter is employed, the portions of the DC bus directly connected (e.g., 125b) to the energy storage device <NUM> and at the input connection to the DC/DC converter are considered variable, while the portion at the output of the DC/DC converter <NUM> connected to the DC bus <NUM>, (e.g., 125a) are considered fixed and regulated.

The battery management system <NUM> monitors the performance of the energy storage device <NUM>. For example, monitoring the state of charge of the energy storage device <NUM>, a state of health of the energy storage device <NUM>, and a temperature of the energy storage device <NUM>. Examples of the energy storage device <NUM> may include a battery system (e.g., a battery or bank of batteries), fuel cells, flow battery, ultracapacitors, and others devices capable of storing and outputting electric energy that may be direct current (DC). The energy storage device <NUM> may include a battery system, which may employ multiple batteries organized into battery banks.

If the energy storage system <NUM> includes a battery system for the energy storage device <NUM>, the battery system may have a voltage potential within a range of about two-hundred volts (200V) to about six-hundred volts (600V). Generally, the higher the voltage, the greater is the sustainability of electric power which is preferred. However, with increases in the voltage, the size and weight of the battery/batteries in an energy storage device <NUM> increase. Increased size and weight are generally not preferred when transporting cargo. Additionally, if the energy storage device <NUM> is a battery, then in order to increase either voltage and/or current, the batteries need to be connected in series or parallel depending upon electrical needs. Higher voltages in a battery energy storage device <NUM> will require more batteries in series than lower voltages, which in turn results in bigger and heavier battery energy storage device <NUM>. A lower voltage and higher current system may be used, however such a system may require larger cabling or bus bars. As a result, commonly the selection and integration of the energy storage device <NUM>, in a power system requires tradeoffs between capacity current, size weight and the like. In addition, the voltage and current capability of the energy storage device <NUM> may also require tradeoffs on the architecture of the power system such as direct connection or employing a DC/DC converter as described herein.

In one embodiment, the energy storage device <NUM> may be contained within the structure <NUM> of the TRU <NUM>. In an embodiment, the energy storage device <NUM> is located with the TRU <NUM>, however, other configurations are possible. In another embodiment, the energy storage device <NUM> may be located with the container <NUM> such as, for example, underneath the cargo compartment <NUM>. Likewise, the DC/DC converter <NUM> may be located with the container <NUM> such as, for example, underneath the cargo compartment <NUM>, however, in some embodiments it may be desirable to have the DC/DC converter <NUM> in close proximity to the power management system <NUM> and/or the TRU <NUM> and TRU controller <NUM>. It will be appreciated that in one or more embodiments, while particular locations are described with respect to connection and placement of selected components including the energy storage device <NUM> and/or DC/DC converter <NUM>, such descriptions are merely illustrative and are not intended to be limiting. Varied location, arrangement and configuration of components is possible and within the scope of the disclosure.

The battery management system <NUM> and DC/DC converter <NUM> are operably connected to and interface with the TRU controller <NUM>. The TRU controller <NUM> receives information regarding the status of energy storage system <NUM>, including the energy storage device <NUM> to provide control inputs to the DC/DC converter <NUM> to monitor the energy storage device <NUM>, as well as control charge and discharge rates for the energy storage device <NUM>.

In an embodiment associated with the generator power converter <NUM> is an AC/DC converter and configured to receive the three phase AC power <NUM> (e.g., at AC voltage V<NUM>, AC current I<NUM> a frequency f<NUM>), from the generator <NUM> and convert it to a DC power denoted <NUM> comprising a second DC voltage V<NUM>, a second DC current I<NUM>. The second DC power <NUM> is transmitted from the generator power converter <NUM> to the DC bus <NUM> and power management system <NUM>. In an embodiment, the generator power converter <NUM> is configured to provide the second DC power <NUM> based of the requirements of the TRU <NUM>. In an embodiment, the generator power converter <NUM> includes a voltage control function <NUM>, a current control function <NUM>, are each configured to facilitate the conversion. In an embodiment, the TRU controller <NUM> provides command signals denoted <NUM>, and <NUM> to a voltage control function <NUM>, current control function <NUM>, respectively. The command signals <NUM>, and <NUM> are generated by the TRU controller <NUM> based on the power consumption requirements of the TRU <NUM> as discussed further herein. In addition, the TRU controller <NUM> may receive status information as depicted by <NUM>, <NUM> regarding the generator power converter <NUM>, and generator <NUM> respectively. Likewise, the generator power converter may receive control signal or provide status signals to TRU controller <NUM>, the power management system <NUM>, or energy storage system <NUM> for mode selection and diagnostic purposes. In an embodiment, the communications may be over standard communication interfaces such as CAN, RS-<NUM>, and the like. Moreover, as is discussed further herein, the communications may be wired or wireless.

In this embodiment, the generator power converter <NUM>, the voltage control function <NUM> includes a voltage regulation function and is configured to monitor the output voltage from the generator <NUM> and maintains a constant DC voltage out of the voltage control function <NUM>. The voltage control function <NUM> communicates status to the TRU Controller <NUM>. The current control function <NUM> monitors and communicates to the TRU <NUM> the status of current draw from the generator <NUM>. In an embodiment, the current may be limited depending on the power demands of the TRU <NUM>. Finally, in an embodiment a frequency converter function <NUM> may also monitors the frequency of the three phase power <NUM> produced by the generator <NUM> to facilitate the conversion of the three phase power <NUM> to the second DC power <NUM> as determined by the voltage control function <NUM> and the TRU controller <NUM> for supply to the power management system <NUM> and ultimately the TRU <NUM>. The generator power converter <NUM> may be a stand-alone unit configured to be in close proximity to or even integral with the generator <NUM>.

Continuing with <FIG>, as described earlier, the power supply interface <NUM> may include, interfaces to various power sources <NUM> managed and monitored by the TRU controller <NUM>. The TRU controller <NUM> and the power management system <NUM> manages and determines electrical power flows in the power supply interface <NUM> based upon the operational needs of the TRU <NUM> and the capabilities of the components in the power supply interface <NUM>, (e.g., generator <NUM>, converter <NUM>, energy storage device <NUM>, and the like. The TRU controller determines the status of various power sources <NUM>, controls their operation, and directs the power to and from the various power sources <NUM> and the like based on various requirements of the TRU <NUM>.

In an embodiment there are five primary power flows associated with the power supply interface <NUM> and specifically the DC bus <NUM> managed by the TRU controller <NUM> and the power management system <NUM>. First, the power into the /dc bus <NUM> supplied via the generator <NUM> or generator power converter <NUM>, e.g., second DC power <NUM>). Second, the power supplied to the DC bus <NUM> when operably connected to grid power source <NUM>. Third the power supplied to the DC bus from an energy storage device <NUM>. Fourth, the power directed from the DC bus <NUM> to the energy storage device <NUM>. Finally, the DC power directed to the power management system <NUM> and TRU <NUM> from the DC bus <NUM>.

The power flows will be transferred through different paths based on the requirements placed on the power management system <NUM> and particular configuration of the power supply interface <NUM>. The DC bus <NUM> and the power management system <NUM> operates as a central power bus to connect various power sources <NUM> together to supply the power needs of the TRU <NUM>. The TRU controller and power management system <NUM> controls switching, directing, or redirecting power to/from the five power flows as needed to satisfy the power requirements of the TRU <NUM>.

Turning now to <FIG> each providing a simplified diagram depicting each of the various possible power flow combinations in the power supply interface <NUM> associated with the DC bus <NUM>. <FIG> depict power flows for power supplied from the generator <NUM> and/or generator power converter <NUM> (e.g., second DC power). Referring now to <FIG>, in an embodiment that does not form part of the present invention, the logic employed by the TRU controller <NUM> for directing the power on the DC bus <NUM> and to the power management system <NUM> if the TRU <NUM> is operating. If so, and the energy storage system <NUM> indicates that the energy storage device <NUM> is exhibiting a charge state that is less than a selected threshold, then the power on the DC bus <NUM> is directed to the power management system <NUM> and thereby the TRU <NUM> and the energy storage system <NUM> for recharging the energy storage device <NUM>. In an embodiment, priority is given to satisfying the power requirements of the TRU <NUM>. Any remaining power may be directed to the recharging application for the energy storage system <NUM>. It should be appreciated that while particular threshold of <NUM>% is disclosed and employed for the described embodiments, such values and description are merely illustrative. Other values and applications for the thresholds are possible.

Referring now to <FIG> as well, the figure depicts a second instance for power flows for power supplied from the generator <NUM> and/or generator power converter <NUM>. In this embodiment, if the TRU <NUM> is operating, and the energy storage system <NUM> indicates that the energy storage device <NUM> is exhibiting a state of charge that is in excess of a selected threshold, then the power on the DC bus <NUM> is directed only to the power management system <NUM> to power only the TRU <NUM>, (as the and the energy storage system <NUM> does not yet require recharging). Similarly, in yet another embodiment, as depicted by <FIG>, a third power flow for power supplied from the generator <NUM> and/or generator power converter <NUM>. In this embodiment, the logic employed by the TRU controller <NUM> for directing the power to the power management system <NUM> addresses an instance when the TRU <NUM> is inoperative, and the energy storage system <NUM> indicates that the energy storage device <NUM> is exhibiting a state of charge that is less than a selected threshold (in this instance <NUM>%, though other thresholds are possible). In this embodiment, the DC power on the DC bus <NUM> is directed only to the energy storage system <NUM> for recharging the energy storage device <NUM>.

Turning now to <FIG>, which depict power flows for power supplied from the grid power source <NUM>. In an embodiment as depicted in <FIG>, the logic employed by the TRU controller <NUM> for directing the power from the grid power source <NUM> determines if the TRU <NUM> is operating and the generator <NUM> (or the generator power converter <NUM>) is inoperative. If so, and the energy storage system <NUM> indicates that the energy storage device <NUM> is exhibiting a charge state that is less than a selected threshold, then power is directed from the DC bus <NUM> to both the power management system <NUM> and then the TRU system <NUM> and the energy storage system <NUM> for recharging the energy storage device <NUM>. In an embodiment, once again, priority is given to satisfying the power requirements of the TRU system <NUM>. Any remaining power may be directed to the recharging application for the energy storage system <NUM>. It should be appreciated that while particular threshold of <NUM>% is disclosed and employed for the described embodiments, such values and description are merely illustrative. Other values and applications for the thresholds are possible.

Referring now to <FIG> as well, the figure depicts a second instance for power flows for power supplied from the grid power source <NUM> when the generator <NUM> is inoperative. In this embodiment, if the TRU <NUM> is operating, and the energy storage system <NUM> indicates that the energy storage device <NUM> is exhibiting a state of charge that is in excess of a selected threshold, then the DC power on the DC bus <NUM> is directed only to the power management system <NUM> directs and to the TRU <NUM>, (as the energy storage system <NUM> does not yet require recharging). Similarly, in yet another embodiment, as depicted by <FIG>, a third power flow for power supplied from the grid power source <NUM> when the generator <NUM> is inoperative. In this embodiment, the logic employed by the TRU controller <NUM> for directing the power on the DC bus <NUM> addresses an instance when the TRU <NUM> is also inoperative, and the energy storage system <NUM> indicates that the energy storage device <NUM> is exhibiting a state of charge that is less than a selected threshold (in this instance <NUM>%, though other thresholds are possible). In this embodiment, the power on the DC bus <NUM> is directed only to the energy storage system <NUM> for recharging the energy storage device <NUM>. In an embodiment, priority is given to satisfying the power requirements of energy storage system <NUM>.

Turning now <FIG>, which depict power flows for power supplied to the power management system <NUM> and the TRU <NUM> under selected conditions for operating from the energy storage system <NUM> as well. In <FIG> power flows to the TRU <NUM> are provided from the generator <NUM> and/or generator power converter <NUM> (e.g., second DC power <NUM>) as well as from the energy storage system <NUM>. In an embodiment, the logic employed by the TRU controller <NUM> for directing the power to the DC bus <NUM> and the power management system <NUM> determines if the TRU <NUM> is operating. If so, and the energy storage system <NUM> indicates that the energy storage device <NUM> is exhibiting a charge state of greater than a selected threshold, then power from both the generator <NUM> (or generator power converter <NUM>) and the energy storage system <NUM> is directed to DC bus <NUM> and then to the power management system <NUM> and thereby the TRU <NUM>. In an embodiment, a threshold of <NUM> percent is employed for the state of charge of the energy storage device <NUM>. In this embodiment, power is provided by the energy storage system <NUM> and thereby discharging the energy storage device <NUM>. In an embodiment, priority is given to satisfying the power requirements of the TRU <NUM>. This embodiment may be employed under conditions where the output power of the generator <NUM> and/or generator power converter <NUM> is less that that needed to operate the TRU <NUM>. It should be appreciated that while particular threshold of <NUM>% is disclosed and employed for the described embodiments, such values and description are merely illustrative. Other values and applications for the thresholds are possible. For example, in some instances it may be desirable prioritize operation of the TRU <NUM> such that fully draining the energy storage device <NUM> is acceptable. Likewise, in other embodiments, it may be desirable to modify the function or curtail the operation of the TRU <NUM> to avoid excessively discharging the energy storage device <NUM>.

Referring now to <FIG> as well, the figure depicts a second instance for power flows from the energy storage system <NUM> alone. In this embodiment, if the TRU <NUM> is operating, but the generator <NUM> and/or the generator power converter <NUM> is inoperative, if the energy storage system <NUM> indicates that the energy storage device <NUM> is exhibiting a state of charge that is in excess of a selected threshold, then the power on the DC bus is directed to the power management system <NUM>, which then provides power to the TRU <NUM>. In an embodiment a threshold of <NUM> percent is employed for the state of charge of the energy storage device <NUM>. In this embodiment, power is provided by the energy storage system <NUM> and thereby discharging the energy storage device <NUM>. In an embodiment, priority is given to satisfying the power requirements of the TRU <NUM>. Once again, this embodiment may be employed under conditions where the output power of the generator <NUM> and/or generator power converter <NUM> is less that that needed to operate the TRU <NUM>. It should be appreciated that while particular threshold of <NUM>% is disclosed and employed for the described embodiments, such values and description are merely illustrative. Other values and applications for the thresholds are possible. For example, in some instances it may be desirable prioritize operation of the TRU <NUM> such that fully draining the energy storage device <NUM> is acceptable. Likewise, in other embodiments, it may be desirable to modify the function or curtail the operation of the TRU to avoid excessively discharging the energy storage device <NUM>.

Returning to <FIG>, in another embodiment and specialized mode of operation and power flow for the TRU system <NUM> and the power supply interface <NUM>. In this embodiment, referred to as a fail operational or "limp home" mode, the power supply interface <NUM> is configured such that, in selected modes of operation power is directed to the TRU <NUM> from the tractor or vehicle <NUM>. In an embodiment, should the energy storage device <NUM> exhibit a SOC below a selected threshold e.g., <<NUM>% and the generator <NUM>/generator power converter <NUM> is not operable but the TRU system <NUM> is operable and requires power, TRU power could be drawn from the power system of the tractor or truck. (i.e. tie into the energy storage device or generator of the tractor/truck). Moreover, it should be appreciated that the described embodiments while generally referring the generator <NUM> being installed on the trailer portion of the vehicle, <NUM>, such description is merely illustrative. In another embodiment, the generator <NUM> or another generator could be installed at a hub or axle of the tractor portion of the vehicle <NUM> without loss of generality and still be fully applicable to the described embodiments. In an embodiment, the tractor/truck power may be routed to the power supply interface <NUM> through a grid plug <NUM>. Alternately connectable between the grid power source <NUM> and the vehicle power. For example, in operation, when vehicle <NUM> trailer is in operation, for example, on delivery, grid plug <NUM> would be plugged into the tractor/trailer's electric PTO and act as mobile grid source. The TRU controller <NUM> would be programmed to determine if the grid plug is active and if so, to pull power (or supplement generator power) only if energy storage device SOC is below threshold as alternative to modify the function or curtail the operation of the TRU system <NUM>.

Turning now to <FIG> depict a plurality of possible configurations for the power supply interface <NUM>. <FIG> depicts a simplified block diagram of the power supply interface <NUM> as described herein. <FIG> depicts the single DC bus <NUM> in a fixed configuration. In this embodiment, the DC bus is split with a variable side 125b between the energy storage device <NUM> and the DC/DC converter <NUM> and a fixed DC bus <NUM>, 125a on the output side of the DC/DC converter <NUM> of the energy storage system <NUM>.

<FIG> depicts a simplified block diagram of the power supply interface <NUM> in accordance with another embodiment as described herein. <FIG> depicts a configuration of the power supply interface <NUM> where the grid power supply <NUM> and grid power converter <NUM> are commonly connected with the energy storage device <NUM> on the DC bus 125b in a variable configuration. In this embodiment the DC/DC converter <NUM> isolates the variable DC bus 125b from the fixed DC bus 125a which includes the output of the DC/DC converter <NUM> of the energy storage system <NUM> and the output of the generator power converter <NUM> commonly connected with the DC/AC converter <NUM> of the power management system <NUM> to provide power to the TRU system <NUM>.

Likewise, <FIG> depicts a simplified block diagram of the power supply interface <NUM> in accordance with still yet another embodiment as described herein. <FIG> depicts a configuration of the power supply interface <NUM> where the generator <NUM> and the output of the generator power converter <NUM> are connected with the energy storage device <NUM> on the variable DC bus 125b in a variable configuration. The DC/DC converter <NUM> of the energy storage system forming the fixed DC bus denoted once again 125a, once again DC/DC converter <NUM> isolates the fixed DC bus 125a from the variable DC bus 125b. In addition, the output of the DC/DC converter <NUM> of the energy storage system <NUM> is connected along with grid power converter <NUM> to fixed DC bus 125a, providing power the DC/AC converter <NUM> of the power management system <NUM> to provide power to the TRU system <NUM>.

The TRU <NUM> may further include a renewable power source <NUM> (<FIG>) configured to recharge the batteries of the energy storage device <NUM>. One embodiment of a renewable power source <NUM> may be solar panels mounted, for example, to the outside of the top wall <NUM> of the container <NUM> (also see <FIG>). For example the renewable power source <NUM> could generate all or a portion of the needed low voltage DC power for the TRU controller <NUM>. Once again, such a configuration simplifies the wiring and routing of the system design by eliminating an additional set of DC cabling from the energy storage device <NUM> beyond the HV cabling going toe the AC/DC converter <NUM>.

Benefits of the present disclosure when compared to more traditional systems include no fuel carriage, fuel system and fuel consumption, and a refrigeration unit that emits less noise and no combustion byproducts. Yet further, the present disclosure includes an energy storage device that is conveniently and efficiently recharged to meet the power demands of the refrigeration unit.

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 a device for practicing the embodiments.

Claim 1:
A power system architecture for powering a transportation refrigeration system (<NUM>) comprising:
a transport refrigeration unit TRU (<NUM>) operable in a vapor compression cycle, the TRU (<NUM>) having a compressor (<NUM>) configured to compress a refrigerant, an evaporator heat exchanger (<NUM>) operatively coupled to the compressor (<NUM>), an evaporator fan (<NUM>) configured to provide return airflow from a return air intake and flow the return airflow over the evaporator heat exchanger (<NUM>), the TRU (<NUM>) also including a TRU controller (<NUM>) configured to execute a process to determine an AC power requirement for the TRU (<NUM>);
a generator power converter (<NUM>) configured to receive a first generator three phase AC power (<NUM>) from an alternating current AC generator (<NUM>) operably coupled to an axle or wheel hub, and configured to provide a generator DC power (<NUM>);
a grid power converter (<NUM>) configured to receive a grid three phase AC power from a grid power source (<NUM>) operable to provide the grid three phase AC power; the grid power converter (<NUM>) operable to provide a grid DC power (<NUM>);
an energy storage device (<NUM>), the energy storage device (<NUM>) operable to provide a variable DC power (<NUM>) and connected to a variable DC bus (125b);
a power management system (<NUM>) operably connected to direct power (<NUM>) to the TRU (<NUM>) based at least in part on at least the AC power requirement; and characterised by
an energy storage system (<NUM>) including the energy storage device (<NUM>), a first energy storage system DC/DC converter (<NUM>) configured to convert the variable DC power (<NUM>) on the variable DC bus (125b) to a fixed DC power (<NUM>) on a fixed DC bus (125a) to provide the fixed DC power (<NUM>) to the power management system (<NUM>) based at least in part on the AC power requirement, and a second energy storage system DC/DC converter (<NUM>) configured to convert at least a portion of the fixed DC power (<NUM>) on the fixed DC bus (125a) to supply the variable DC bus (125b) and the energy storage device (<NUM>).