Electrical architecture for powering transport refrigeration units

Abstract

A power system architecture configured to power a transport refrigeration system (20) based on a determined AC power requirement. The system (20) includes a generator power converter (164) configured to receive generator three-phase AC power (163) from an AC generator (162) and provide generator DC power (165). The system (20) also includes: a grid power converter (184) configured to receive grid three-phase AC power from a grid power source (182) and provide grid DC power (185); an energy storage device (152) operable to provide DC power (157) and connected to a variable DC bus; and a power management system (190) operably connected to direct power (195) to a TRU (26) based at least on the AC power requirement.

Description

Technical Field

[0001] The subject matter disclosed herein relates generally to transport refrigeration units, and more particularly to apparatus and methods for powering a transport refrigeration unit utilizing a generator and an energy storage device. Background Art

[0002] A conventional refrigerated freight truck or refrigerated tractor trailer (such as those used to transport goods via sea, rail or road) is a truck, trailer or cargo compartment that generally defines a cargo compartment and is modified to include a refrigeration system located at one end of the truck, trailer or cargo compartment. The refrigeration system typically includes a compressor, a condenser, an expansion valve, and an evaporator, which are connected in series in a closed refrigerant circuit by refrigerant lines according to a known refrigerant vapor compression cycle. A power unit such as a combustion engine drives the compressor of the refrigeration unit and may be a 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 through a belt drive or a mechanical shaft-to-shaft coupling. In other systems, the engine of the refrigeration unit drives a generator that generates electrical power, which in turn drives the compressor.

[0003] Under current environmental trends, improvements in transport refrigeration units are desirable, particularly toward efficiency, sound, and environmental impact. With regard to environmentally friendly refrigeration units, improvements in reliability, cost, and weight reduction are also desirable. Summary of the invention

[0004] According to one embodiment, described herein is a power system architecture configured to power a transport refrigeration system based on a determined AC power requirement. The system includes a generator power converter configured to receive generator three-phase AC power from an alternating current (AC) generator operably coupled to an axle or hub and provide generator DC power. The system also includes: a grid power converter configured to receive grid three-phase AC power from a grid power source, the grid power converter operable to provide grid DC power; an energy storage device operable to provide DC power and connected to a DC bus; and a power management system operably connected to direct power to a transport refrigeration unit TRU based at least on the AC power requirement.

[0005] In addition to one or more of the above features, or as an alternative, further embodiments may include a DC / DC converter operably connected to the variable DC bus, the DC / DC converter configured to convert the variable DC power to fixed DC power on the fixed DC bus.

[0006] In addition to or as an alternative to one or more of the above features, further embodiments may include a generator power converter configured to receive a first three-phase AC power provided by an AC generator and transmit the generator DC power to one of a fixed DC bus or a variable DC bus.

[0007] In addition to one or more of the above features, or as an alternative, further embodiments may include: the generator power converter includes an AC / DC converter, and the generator three-phase AC power presents a first AC voltage and a first AC current at a first frequency, and the generator DC power presents a second DC voltage and a second DC current.

[0008] In addition to or as an alternative to one or more of the above features, further embodiments may include that the generator power converter includes a voltage control function and a current control function, wherein at least the voltage control function is at least partially responsive to the AC power demand.

[0009] In addition to or as an alternative to one or more of the above features, further embodiments may include a grid power converter configured to receive a first three-phase AC power provided by a grid power source and transmit grid DC power to one of a fixed DC bus or a variable DC bus.

[0010] In addition to one or more of the above features, or as an alternative, further embodiments may include: the grid power converter includes an AC / DC converter, and the grid three-phase AC power presents a grid AC voltage and a grid AC current at a grid frequency, and the grid DC power presents a grid DC voltage and a grid DC current.

[0011] In addition to or as an alternative to one or more of the above features, further embodiments may include that the grid power converter includes a voltage control function and a current control function, wherein at least the voltage control function is at least partially responsive to the AC power demand.

[0012] In addition to one or more of the above features, or as an alternative, further embodiments may include: the energy storage system includes an energy storage device and at least one of a first energy storage system DC / DC converter and a second energy storage system DC / DC converter, wherein the first energy storage system DC / DC converter is configured to provide DC power to a power management system based at least in part on AC power requirements, and the second energy storage system DC / DC converter is configured to convert at least a portion of the DC power on the fixed DC bus to supply the variable DC bus and the energy storage device.

[0013] In addition to or as an alternative to one or more of the above features, further embodiments may include a battery management system operably connected to the TRU controller and configured to monitor at least the state of charge of the energy storage device.

[0014] In addition to one or more of the above features, or as an alternative, further embodiments may include: the energy storage system DC / DC converter and the second energy storage system DC / DC converter are integrated, and wherein the first energy storage system DC / DC converter is operably connected to the TRU controller and is configured to direct power flow to the fixed DC bus and the power management system and from the fixed DC bus to the variable DC bus based on at least one of the AC power demand and the charge state of the energy storage device.

[0015] In addition to or as an alternative to one or more of the above features, further embodiments may include that the energy storage device includes at least one of a battery, a fuel cell, and a flow battery.

[0016] In addition to or in the alternative to one or more of the above features, further embodiments may include a power management system configured to receive DC power from one of the fixed DC bus and the variable DC bus and provide a second three-phase AC power to the TRU based at least on the AC power requirement.

[0017] In addition to or as an alternative to one or more of the above features, further embodiments may include that the power management system includes a DC / AC converter, and that the second three-phase AC power exhibits a second three-phase AC voltage and a second AC current at a second frequency.

[0018] In addition to or as an alternative to one or more of the above features, further embodiments may include: a grid power converter, a generator power converter, an energy storage device, and a power management system operably connected to a variable DC bus.

[0019] In addition to one or more of the above features, or as an alternative, further embodiments may include: the grid power converter, the generator power converter, the power management system, and the energy storage system DC / DC converter are operably connected to a fixed DC bus, and the energy storage system DC / DC converter and the energy storage device are operably connected to a variable DC bus.

[0020] In addition to one or more of the above features, or as an alternative, further embodiments may include: the grid power converter and the power management system and the energy storage system DC / DC converter are connected to a fixed DC bus, and the energy storage system DC / DC converter and the generator power converter and the energy storage device are operably connected to a variable DC bus.

[0021] In addition to one or more of the above features, or as an alternative, further embodiments may include: the grid power converter, the generator power converter, the energy storage system DC / DC converter and the energy storage device are connected to a variable DC bus, and the energy storage system DC / DC converter and the power management system are operably connected to a fixed DC bus.

[0022] In addition to one or more of the above features, or as an alternative, further embodiments may include: the grid power converter, power management system, energy storage system DC / DC converter and energy storage device are connected to a variable DC bus, and the energy storage system DC / DC converter and generator power converter are operably connected to a fixed DC bus.

[0023] In addition to one or more of the above features, or as an alternative, further embodiments may include: the grid power converter, the generator power converter, the energy storage system DC / DC converter are connected to a fixed DC bus, and the energy storage system DC / DC converter, the energy storage device and the power management system are operably connected to a variable DC bus.

[0024] In addition to one or more of the above features, or as an alternative, further embodiments may include: the grid power converter and the energy storage system DC / DC converter are connected to a fixed DC bus, and the energy storage system DC / DC converter, the generator power converter, the energy storage device and the power management system are operably connected to a variable DC bus.

[0025] In addition to one or more of the above features, or as an alternative, further embodiments may include: the generator power converter and the power management system and the energy storage system DC / DC converter are connected to a fixed DC bus, and the energy storage system DC / DC converter and the grid power converter and the energy storage device are operably connected to a variable DC bus.

[0026] In addition to one or more of the above features, or as an alternative, further embodiments may include a return air temperature (RAT) sensor disposed in the return air flow and configured to measure the temperature of the return air flow, the RAT sensor being operably connected to the TRU controller, the TRU controller being configured to execute a process for determining the AC power requirement of the TRU based at least in part on the RAT.

[0027] Also described herein in an embodiment is a method of generating power and directing power to a transport refrigeration unit system having: a compressor configured to compress a refrigerant; an evaporator heat exchanger operatively coupled to the compressor; an evaporator fan configured to provide a return airflow from a return air inlet and to flow the return airflow over the evaporator heat exchanger; and a TRU controller operable to perform the method. The method includes: determining an AC power requirement of the TRU; providing a generator DC power from a generator power converter operatively connected to an alternating current (AC) generator operatively connected to an axle or hub; and providing grid DC power from a grid power converter operatively connected to a grid power source providing grid three-phase AC power. The method also includes: providing DC power to a power management system from a variable DC bus operatively connected to an energy storage device; and directing three-phase AC power to the TRU by the power management system, the power management system operatively connected to the TRU, the directing being based at least in part on the AC power requirement.

[0028] In addition to or as an alternative to one or more of the above features, further embodiments may include that the energy storage device comprises a battery system.

[0029] Technical effects of embodiments of the present disclosure include a transport refrigeration unit that is connected to and powered by an external generator system via a generator power converter, wherein the power generated by the generator and converted by the generator power converter is based on the AC power requirement of the transport refrigeration unit.

[0030] Unless otherwise explicitly stated, the aforementioned features and elements may be combined in various combinations in a non-exclusive manner. These features and elements and their operation will become more apparent from the following description and accompanying drawings. However, it should be understood that the following description and accompanying drawings are intended to be illustrative and explanatory in nature, and non-restrictive. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The subject matter which is regarded as the present disclosure is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the present disclosure will be apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0032] The following description should not be considered limiting in any way. Referring to the drawings, similar elements are similarly labeled:

[0033] Figure 1 is a perspective view of a transport refrigeration system having a transport refrigeration unit according to an embodiment of the present disclosure as one non-limiting embodiment of the present disclosure;

[0034] Figure 2is a schematic diagram of a transport refrigeration unit according to an embodiment of the present disclosure;

[0035] Figure 3 is a block diagram of a transport refrigeration unit and power system according to an embodiment of the present disclosure;

[0036] Figure 4A Describes the power flow of a power management system according to an embodiment of the present disclosure;

[0037] Figure 4B Describes the power flow of a power management system according to an embodiment of the present disclosure;

[0038] Figure 4C Describes the power flow of a power management system according to an embodiment of the present disclosure;

[0039] Figure 4D Describes the power flow of a power management system according to an embodiment of the present disclosure;

[0040] Figure 4E Describes the power flow of a power management system according to an embodiment of the present disclosure;

[0041] Figure 4F Describes the power flow of a power management system according to an embodiment of the present disclosure;

[0042] Figure 4G Describes the power flow of a power management system according to an embodiment of the present disclosure;

[0043] Figure 4H Describes the power flow of a power management system according to an embodiment of the present disclosure;

[0044] Figure 5A is a block diagram of a transport refrigeration unit and power system according to an embodiment of the present disclosure;

[0045] Figure 5B is a block diagram of a transport refrigeration unit and power system according to an embodiment of the present disclosure;

[0046] Figure 5C is a block diagram of a transport refrigeration unit and power system according to an embodiment of the present disclosure;

[0047] Figure 5D is a block diagram of a transport refrigeration unit and power system according to an embodiment of the present disclosure;

[0048] Figure 5E is a block diagram of a transport refrigeration unit and power system according to an embodiment of the present disclosure;

[0049] Fig. 5F is a block diagram of a transport refrigeration unit and power system according to an embodiment of the present disclosure;

[0050] Figure 5G is a block diagram of a transport refrigeration unit and power system according to an embodiment of the present disclosure; and

[0051] Figure 5H is a block diagram of a transport refrigeration unit and power system according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0052] A detailed description of one or more embodiments of the disclosed apparatus and method is presented herein by way of illustration and not limitation, with reference to the accompanying drawings.

[0053] Reference Figure 1 , a transport refrigeration system 20 of the present disclosure is shown. In the illustrated embodiment, the transport refrigeration system 20 may include a tractor or vehicle 22, a cargo box 24, and an engine-less transport refrigeration unit (TRU) 26. The cargo box 24 may be towed by the vehicle 22. It is understood that the embodiments described herein may be applied to shipping cargo boxes shipped by rail, sea, air, or any other suitable cargo box, and thus the vehicle may be a truck, train, ship, airplane, helicopter, etc.

[0054] The vehicle 22 may include an operator's cabin or cab 28 and a combustion engine 42, which is part of the powertrain or drive system of the vehicle 22. In some cases, the vehicle 22 may be a hybrid or all-electric configuration with an electric motor to provide propulsion to the vehicle. In some configurations, the TRU system 26 may be engineless. In some embodiments, a small engine or the engine of the vehicle 22 may be used to power or partially power the TRU 26. The cargo compartment 24 may be coupled to the vehicle 22 and thus towed or propelled to a desired destination. The trailer may include a top wall 30, a bottom wall 32 that is opposite and spaced from the top wall 30, two side walls 34 that are spaced from each other and opposite, and a front wall 36 and a rear wall 38 that are opposite, wherein the front wall 36 is closest to the vehicle 22. The cargo compartment 24 may also include a door (not shown) at the rear wall 38 or any other wall. Walls 30, 32, 34, 36, 38 together define the boundaries of the cargo compartment 40. Typically, the transport refrigeration system 20 is used to transport and distribute items, such as, for example, perishable items and environmentally sensitive items (referred to herein as perishable items). Perishable items may include, but are not limited to, fruits, vegetables, grains, beans, nuts, eggs, dairy products, seeds, flowers, meat, poultry, fish, frozen foods, blood, pharmaceuticals, or any other suitable goods that require cold chain transportation. In the illustrated embodiment, the TRU 26 is associated with the cargo compartment 24 to provide the cargo compartment 40 with desired environmental parameters, such as, for example, temperature, pressure, humidity, carbon dioxide, ethylene, ozone, light exposure, vibration exposure, and other conditions. In other embodiments, the TRU 26 is a refrigeration system capable of providing a desired temperature and humidity range.

[0055] Reference Figure 1 and Figure 2 , the cargo box 24 is typically configured to store cargo (not shown) in a compartment 40. The engineless TRU 26 is typically integrated into the cargo box 24 and may be mounted to the front wall 36. The cargo is maintained at a desired temperature by cooling the compartment 40 via the TRU 26, which circulates a refrigerated airflow into and through the cargo compartment 40 of the cargo box 24. It is also contemplated and understood that the TRU 26 may be applied to any transport compartment (e.g., a shipping or transport compartment), not necessarily those used in tractor-trailer systems. In addition, the transport compartment 24 may be part of the vehicle 22, or configured to be removed from the frame and wheels (not shown) of the cargo box 24 for alternative shipping means (e.g., sailing, rail, flight, etc.).

[0056] The components of the engineless TRU 26 may include a compressor 58, an electric compressor motor 60, a condenser 64 that may be air cooled, a condenser fan assembly 66, a receiver 68, a filter dryer 70, a heat exchanger 72, an expansion valve 74, an evaporator 76, an evaporator fan assembly 78, a suction regulating valve 80, and a controller 82, which may include a computer-based processor (e.g., a microprocessor), etc., as will be further described herein. The operation of the engineless TRU 26 can be best understood by starting at the compressor 58, where the suction gas (i.e., natural refrigerant, hydrofluorocarbon (HFC) R-404a, HFCR-134a, etc.) enters the compressor 58 at the suction port 84 and is compressed to a higher temperature and pressure. The refrigerant gas is discharged from the compressor 58 at the outlet port 85 and may then flow into the tube(s) 86 of the condenser 64.

[0057] The air flowing across a plurality of condenser coil fins (not shown) and tube 86 cools the gas to its saturation temperature. The air flow across the condenser 64 can be promoted by one or more fans 88 of the condenser fan assembly 66. The condenser fan 88 can be driven by a corresponding condenser fan motor 90 of the fan assembly 66, and the corresponding condenser fan motor 90 can be electric. By removing latent heat, the refrigerant gas in the tube 86 condenses into a high-pressure and high-temperature liquid, and flows to the receiver 68, which provides storage for excess liquid refrigerant during low-temperature operation. The liquid refrigerant can pass from the receiver 68 through the subcooler heat exchanger 92 of the condenser 64, through the filter dryer 70 that keeps the refrigerant clean and dry, then to the heat exchanger 72 that increases the subcooling of the refrigerant, and finally to the expansion valve 74.

[0058] As the liquid refrigerant passes through the orifice of the expansion valve 74, some of the liquid vaporizes into a gas (i.e., flash gas). Return air from the refrigerated space (i.e., cargo hold 40) flows over the heat transfer surfaces of the evaporator 76. As the refrigerant flows through the plurality of tubes 94 of the evaporator 76, the remaining liquid refrigerant absorbs heat from the return air and, in doing so, vaporizes and thereby cools the return air.

[0059] The evaporator fan assembly 78 includes one or more evaporator fans 96, which can be driven by corresponding fan motors 98, which can be electric. The air flow across the evaporator 76 is promoted by the evaporator fan 96. The refrigerant in vapor form can then flow from the evaporator 76 through the suction regulating valve 80 and return to the compressor 58. The expansion valve 74 can be thermostatic or electrically adjustable. In the embodiment as depicted, the expansion valve 74 is thermostatic. The thermostatic expansion valve temperature sensing package sensor 100 can be located near the outlet of the evaporator tube 94. The temperature sensing package sensor 100 is intended to control the thermostatic expansion valve 74, thereby controlling the refrigerant superheat at the outlet of the evaporator tube 94. It is also contemplated and understood that the above content generally describes a single-stage vapor compression system that can be used for HFCs such as R-404a and R-134a and natural refrigerants such as propane and ammonia. Other refrigeration systems can also be applied, which use carbon dioxide (CO2) refrigerants and can be two-stage vapor compression systems. In another embodiment, the expansion valve 74 may be an electronic expansion valve. In this case, the expansion valve is commanded by the controller 82 to a selected position based on the operating conditions of the vapor compression cycle and the needs of the system.

[0060] A bypass valve (not shown) may facilitate flash gas of the refrigerant to bypass the evaporator 76. This will allow the evaporator coils to be filled with liquid and fully "wetted" to improve heat transfer efficiency. With CO2 refrigerant, this bypass flash gas may be reintroduced into the middle stage of the two-stage compressor 58.

[0061] The compressor 58 and the compressor motor 60 may be coupled via an interconnecting drive shaft 102. The compressor 58, the compressor motor 60, and the drive shaft 102 may all be sealed within a common housing 104. The compressor 58 may be a single compressor. The single compressor may be a two-stage compressor, a scroll compressor, or other compressor suitable for compressing HFCs or natural refrigerants. The natural refrigerant may be CO2, propane, ammonia, or any other natural refrigerant that may include a global warming potential (GWP) of approximately one (1).

[0062] continue Figure 2 , and continue to refer to Figure 1 , Figure 2Also shown is the airflow through the TRU 26 and the cargo compartment 40. The airflow circulates into, through and out of the cargo compartment 40 of the cargo compartment 24 by means of the TRU 26. The return airflow 134 flows from the cargo compartment 40 into the TRU 26 through the return air inlet 136 and across the evaporator 76 via the fan 96, thereby adjusting the return airflow 134 to a selected or predetermined temperature. The conditioned return airflow 134 (now referred to as the supply airflow 138) is supplied to the cargo compartment 40 of the cargo compartment 24 through the refrigeration unit outlet 140, which in some embodiments is located near the top wall 30 of the cargo compartment 24. The supply airflow 138 cools the perishable items in the cargo compartment 40 of the cargo compartment 24. It will be appreciated that the TRU 26 can be further reversed to heat the cargo compartment 24 when, for example, the outside temperature is very low.

[0063] A temperature sensor 142 (i.e., a thermistor, thermocouple, RTD, etc.) is placed in the air stream, on the evaporator 76, at the return air inlet 136, etc., to monitor the temperature of the return airflow 134 from the cargo compartment 40. A sensor signal indicative of the return airflow temperature, designated as RAT, is operably connected to the TRU controller 82 via line 144 to facilitate control and operation of the TRU 26. Likewise, a temperature sensor 146 is placed in the supply airflow 138, on the evaporator 76, at the refrigeration unit outlet 140, to monitor the temperature of the supply airflow 138 directed into the cargo compartment 40. Likewise, a sensor signal indicative of the supply airflow temperature, designated as SAT 14, is operably connected to the TRU controller 82 via line 148 to facilitate control and operation of the TRU 26.

[0064] system

[0065] Now refer to Figure 3 , and continue to refer to Figure 1 and Figure 2, the TRU 26 may include or be operably interfaced with a power source interface, generally shown as 120. The power source interface 120 may include interfaces to / from various power sources, generally shown as 122 and more specifically described herein below, and one or more DC buses, generally shown as 125 and more specifically shown as 125a, 125b, ... 125n. In an embodiment, the power source 122 may include, but is not limited to, an energy storage device 152, a generator 162, and grid power 182. Each of the power sources 122 may be configured to selectively power the TRU 26 as further described herein, including the compressor motor 60, the condenser fan motor 90, the evaporator fan motor 98, the controller 82, and other components 99 of the TRU 26, which may include various solenoids and / or sensors. The controller 82 , through a series of data and command signals over various paths 108 , may control the application of power to the electric motors 60 , 90 , 98 , for example, as dictated by the cooling requirements of the TRU 26 .

[0066] The engineless TRU 26 may include an AC or DC architecture, wherein selected components utilize alternating current (AC) and other components utilize direct current (DC). For example, in an embodiment, the motors 60, 90, 98 may be configured as AC motors, while in other embodiments, the motors 60, 90, 98 may be configured as DC motors. As the power sources 122 supply power to the TRU 26, the operation of the power sources 122 may be managed and monitored by the TRU controller 82 and interfaced to the power management system 190 from the DC bus 125. The power management system 190 is configured to direct power from the various power sources 122, etc., via the DC bus 125 based on the various requirements of the TRU 26. In an embodiment, the TRU controller 82 receives various signals indicating the operating status of the TRU 26, and accordingly determines the power requirements of the TRU system 26, and directs the components of the power source interface 120 and specifically the power management system 190 to accordingly direct power to address the requirements of the TRU 26.

[0067] In one embodiment, the TRU system 26 is controlled to a temperature set point value selected by a user. The TRU controller 82 monitors the RAT and optional SAT as measured by the temperature sensors 142 and 146, respectively. The TRU controller 82 estimates the power requirements of the TRU 26 based on the RAT (among other things), and accordingly provides commands to various components of the power source interface 120 and specifically the power management system 190, the energy storage system 150, and the generator power converter 164 to manage the generation, conversion, and transmission of power in the power source interface 120 and the TRU system 26. By using the measured RAT and the set point value, the power demand is estimated. More specifically, in one embodiment, if (RAT-set point value) is above a first threshold (e.g., >10℉), the TRU system 26 requires full power (e.g., the current demand is known under a known voltage supply). If (RAT - set point value) is between the first threshold and the second threshold, the current requirement is limited (at the known voltage) to achieve a mid-range power (e.g., ~50% power or some power less than 100%). If (RAT - set point value) is below the second threshold, the current is limited (at the voltage) to achieve a minimum power (e.g., ~20% power).

[0068] The TRU controller 82 is configured to control components in the TRU 26 and components of the power source interface 120 according to the operational requirements of the transport refrigeration system 20. The TRU controller 82 is communicatively coupled to the power management system 190, the grid power source 182, the energy storage system 150, and the generator power converter 164 or generator 162. For the TRU power requirements, the TRU controller 82 uses additional information from each of the power sources 122 to provide instructions to affect the grid power source 182 output, the generator 162 and generator power converter 164 output, the charging / discharging of the energy storage system 150, all in order to enable and configure to provide the power required by the TRU 26. In addition, the TRU controller 82 provides instructions to various components in the power source interface 120 to manage the power flow to the DC bus 125 and thereby to the power management system 190 depending on the operating status of the various power sources (i.e., the grid power 182, the energy storage device 152, and the generator 162) and based on the TRU 26 power requirements.

[0069] In an embodiment, the power management system 190 includes a DC / AC converter 194. The DC / AC converter 194 is configured to receive DC power (e.g., a second DC voltage V2, a second DC current I2 from the generator power converter 165; and / or V G ,I G185; and / or a DC voltage 155 from an energy storage device 152; individually or in combination) and generates a three-phase AC power 195 (e.g., at an AC voltage V2, an AC current I2, and a frequency f2) for providing power to the TRU system 26. In an embodiment, the DC / AC converter 194 includes a voltage control function, a current control function, and a frequency control function, all of which are configured to facilitate conversion. In an embodiment, the TRU controller 82 provides a command signal represented by line 191 to the power management system 190. The command is based at least on the power consumption requirements of the TRU 26, as further discussed herein. In addition, the TRU controller 82 may receive status information about the DC / AC converter 194, also depicted by line 191. In an embodiment, communication may be through a standard communication interface such as CAN, RS-485, etc. In addition, as further discussed herein, communication may be wired or wireless.

[0070] As further described herein, there are three power sources 122: grid power 182, generator 162 / generator power converter 164, and energy storage device 152. If the TRU 26 is "on" and operating, the TRU controller 82 knows the power requirements of the TRU system 26, and thus, what power is needed. The TRU controller 82 is also programmed to determine whether grid power (e.g., 182) is available. If grid power is available and the TRU is on and the energy storage device 152 (e.g., battery) SOC indicates a full charge, the grid power will meet the power needs of the TRU system 26. Conversely, if grid power 182 is available and the TRU is on and the energy storage device is not fully charged, the TRU power needs are met as a first priority, and the DC / DC converter 156 will then be activated to provide the necessary charge to the energy storage device 152 as a second priority. In addition, if grid power 182 is available and the TRU is "off", and the energy storage device 152 is not fully charged, the DC / DC converter 156 will be activated to provide the necessary charging current. If grid power 182 is unavailable and generator 162 / generator power converter 164 is inoperable, all TRU power demands are met by energy storage system 150 via energy storage device 152. Finally, if grid power 182 is unavailable and generator 162 / generator power converter 164 is operational, TRU power demands are met by both generator 162 and energy storage system 150.

[0071] As described herein, in operation, the TRU controller 82 identifies the power requirements of the TRU 26 based at least in part on the RAT. The TRU controller 82 communicates the power requirements to the power management system 190 and / or the generator power converter 164 to convert the first three-phase AC power 163 or the first DC power 163a into the second DC power 165 as needed to meet the requirements of the TRU 26 and the energy storage system 150 and specifically the charging requirements of the energy storage device 152.

[0072] When the grid power source 182 is available, the DC bus 125 and thus the power management system 190 can receive power from the grid power source 182. In an embodiment, the grid power source 182 is connected to the DC bus 125 and the power management system 190 via a grid power converter 184. In an embodiment, the power management system 190 can be a stand-alone unit, or integrated with the TRU 26. The grid power source 182 is typically conventional three-phase AC power 220 / 480VAC at 60 or 400Hz. In an embodiment, the grid power converter 184 is a conventional AC / DC converter that is operable to convert the three-phase AC power from the grid power source 182 into DC voltage and current. In one or more embodiments, the grid power converter 184 generates a DC voltage V G and DC current I G Grid DC power 185 is transmitted from grid power converter 184 to DC bus 125 and power management system 190 or elsewhere as described herein.

[0073] The DC bus 125 and the power management system 190 receive power from the generator 162 directly and / or via a generator power converter 164. The generator 162 may be axle or hub mounted and configured to recover rotational energy and convert the rotational energy into electrical energy when the transport refrigeration system 20 is in motion, such as, for example, when the axle of the vehicle 22 rotates due to acceleration, cruising, or braking. In an embodiment, the generator 162 is configured to provide a first three-phase AC power 163, the first three-phase AC power 163 comprising a voltage V1, an AC current I1 at a given frequency f1, represented by the reference numeral 163. The generator 162 may be asynchronous or synchronous. In another embodiment, the generator 162 may be DC, providing a first DC power 163a, the first DC power 163a comprising a DC voltage and a DC current (represented as V 1a and DC current I 1a ). In one or more embodiments, the generator power converter 164 generates a second DC power 165 including a DC voltage V2 and a DC current I2. The second DC power 165 is transmitted from the generator power converter 164 to the DC bus 125 and thereby the power management system 190 or elsewhere as described herein.

[0074] Energy storage systems

[0075] continue Figure 3 and a power source interface 120 and an architecture of various power sources 122 for powering the TRU 26 and its components. In an embodiment, one of the power sources 122 may include, but is not limited to, an energy storage system 150 operably coupled to the power management system 190. The energy storage system 150 transmits DC power 155 to the DC bus 125 via the DC bus 125b and receives DC power 157 from the DC bus 125. The energy storage system 150 may include, but is not limited to, an energy storage device 152 and a battery management system 154. In an embodiment, the battery management system 154 is part of the energy storage device 152 and is integrated with the energy storage device 152. In this embodiment, the DC buses 125a and 125b are directly connected.

[0076] In an embodiment, the DC voltages from the power sources 122 (including the DC voltage 185 from the grid power source 182 and / or the DC voltages V2, I2 165 from the generator power converter 164) are combined to form a DC voltage and current on the buses 125a, 125b, which are directly coupled to the energy storage device 152 to charge and store energy on the energy storage device 152. Conversely, in other embodiments, such as when the grid power source 182 is unavailable, the energy storage device 152 supplies the DC voltage and current 155 directly to the DC buses 125b, 125a and the power management system 190 for powering the TRU 26. In another embodiment, the energy storage system 150 also includes a DC / DC converter 156. In one embodiment, the DC bus 125 and more specifically 125a provides DC power 157 to the DC / DC converter 156 to formulate a DC voltage and current 155 on the DC bus 125b to charge and store energy on the energy storage device 152. Conversely, in other embodiments, the energy storage device 152 supplies the DC voltage and current 155 to the DC / DC converter 156 via the DC bus 125b, and the DC / DC converter 156 operates as a DC / DC converter to supply DC power 157 to the DC bus 125, 125a and the power management system 190 for powering the TRU 26. It should be recognized that as described herein, the DC / DC converter 156 is bidirectional, achieving conversion in both directions to facilitate charging and discharging of the energy storage device 152. Although the DC / DC converter 156 is described as bidirectional, such description is for illustrative purposes only. In operation, the DC / DC converter 156 can be a single integrated unit, or multiple units configured in parallel to operate in opposite directions. It is also worth noting to recognize that in the various embodiments described herein, a variety of architectures are described based on the interconnection between various power sources 122. More specifically, the interconnection between the power sources 122 (e.g., grid power source 182, generator 162, and DC / AC converter 194 of power management system 190) and energy storage device 152 based on the optional application of optional DC / DC converter 156. In various architectures where energy storage device 152 is directly connected (e.g., 125a is directly connected to 125b), that portion of the bus is referred to as variable because the voltage can vary based on the state of charge of energy storage device 152. On the other hand, in the case where a DC / DC converter is employed, the portion of the DC bus that is directly connected to energy storage device 152 and connected to the DC / DC converter at the input connection (e.g., 125b) is considered variable, while the portion at the output of DC / DC converter 156 connected to the DC bus 125 (e.g., 125a) is considered fixed and regulated.

[0077] The battery management system 154 monitors the performance of the energy storage device 152. For example, the state of charge of the energy storage device 152, the health state of the energy storage device 152, and the temperature of the energy storage device 152 are monitored. Examples of the energy storage device 152 may include a battery system (e.g., a battery or battery pack), a fuel cell, a flow battery, a supercapacitor, and other devices capable of storing and outputting electrical energy that may be direct current (DC). The energy storage device 152 may include a battery system that may employ a plurality of batteries organized into a battery pack.

[0078] If the energy storage system 150 includes a battery system for the energy storage device 152, the battery system may have a voltage potential in the range of about two hundred volts (200V) to about six hundred volts (600V). Generally, the higher the voltage, the greater the sustainability of the electric power, which is preferred. However, as the voltage increases, the size and weight of one or more batteries in the energy storage device 152 increase. When transporting goods, the increased size and weight are generally not preferred. In addition, if the energy storage device 152 is a battery, in order to increase the voltage and / or current, the battery needs to be connected in series or in parallel depending on the electrical demand. The higher voltage in the battery energy storage device 152 will require more series batteries than the lower voltage, which in turn leads to a larger and heavier battery energy storage device 152. A system with lower voltage and higher current can be used, but such a system may require larger cables or busbars. Therefore, in a power system, the selection and integration of the energy storage device 152 generally requires a trade-off between capacitive current, size, weight, etc. Additionally, the voltage and current capabilities of energy storage device 152 may also require tradeoffs in the architecture of the power system, such as direct connection or employing a DC / DC converter as described herein.

[0079] In one embodiment, the energy storage device 152 may be housed within the structure 27 of the TRU 26. In an embodiment, the energy storage device 152 is positioned with the TRU 26, however, other configurations are possible. In another embodiment, the energy storage device 152 may be positioned with the cargo compartment 24, such as, for example, below the cargo compartment 40. Likewise, the DC / DC converter 156 may be positioned with the cargo compartment 24, such as, for example, below the cargo compartment 40, however, in some embodiments, it may be desirable to have the DC / DC converter 156 in close proximity to the power management system 190 and / or the TRU 26 and the TRU controller 82. It will be appreciated that in one or more embodiments, while specific locations are described with respect to the connection and placement of selected components including the energy storage device 152 and / or the DC / DC converter 156, such descriptions are merely illustrative and are not intended to be limiting. Variations in the locations, arrangements, and configurations of the components are possible and within the scope of the present disclosure.

[0080] The battery management system 154 and the DC / DC converter 156 are operably connected to and interface with the TRU controller 82. The TRU controller 82 receives information about the status of the energy storage system 150 including the energy storage device 152 to provide control inputs to the DC / DC converter 156 to monitor the energy storage device 152 and control the charging and discharging rates of the energy storage device 152.

[0081] AC Generator / DC Converter

[0082] In an embodiment, associated with the generator power converter 164 is an AC / DC converter configured to receive three-phase AC power 163 (e.g., at an AC voltage V1, an AC current I1, and a frequency f1) from the generator 162 and convert it to a DC power, indicated as 165, which includes a second DC voltage V2 and a second DC current I2. The second DC power 165 is transmitted from the generator power converter 164 to the DC bus 125 and the power management system 190. In an embodiment, the generator power converter 164 is configured to provide the second DC power 165 based on the requirements of the TRU 26. In an embodiment, the generator power converter 164 includes a voltage control function 166 and a current control function 167, each of which is configured to facilitate conversion. In an embodiment, the TRU controller 82 provides command signals, indicated as 169 and 170, to the voltage control function 166 and the current control function 167, respectively. The command signals 169 and 170 are generated by the TRU controller 82 based on the power consumption requirements of the TRU 26, as further discussed herein. In addition, the TRU controller 82 may receive status information depicted by 171, 172 regarding the generator power converter 164 and the generator 162, respectively. Likewise, the generator power converter may receive control signals or provide status signals to the TRU controller 82, the power management system 190, or the energy storage system 150 for mode selection and diagnostic purposes. In an embodiment, the communication may be through a standard communication interface such as CAN, RS-485, etc. Furthermore, as further discussed herein, the communication may be wired or wireless.

[0083] In this embodiment, the generator power converter 164, the voltage control function 166 includes a voltage regulation function and is configured to monitor the output voltage from the generator 162 and maintain a constant DC voltage outside of the voltage control function 166. The voltage control function 166 communicates the status to the TRU controller 82. The current control function 167 monitors and communicates the status of the current drawn from the generator 162 to the TRU 26. In an embodiment, the current may be limited depending on the power requirements of the TRU 26. Finally, in an embodiment, the frequency converter function 168 may also monitor the frequency of the three-phase power 163 produced by the generator 162 to facilitate conversion of the three-phase power 163 into a second DC power 165 as determined by the voltage control function 166 and the TRU controller 82 for supply to the power management system 190 and ultimately to the TRU 26. The generator power converter 164 may be a stand-alone unit that is configured to be in close proximity to the generator 162 or even integrated with the generator 162.

[0084] DC Generator / DC Converter

[0085] In yet another embodiment, for example, when the generator 162 is a DC generator, the generator power converter 164 is a DC / DC converter and is configured to receive the DC power 163a (e.g., at a DC voltage V 1a 、DC current I 1a ) and converts it into a second DC power represented by 165a, which includes a second DC voltage V 2a , the second DC current I 2a. The second DC power 165a is transmitted from the generator power converter 164 to the power management system 190. Again, as described above, the generator power converter 164 is configured to provide the second DC power 165a based on the requirements of the TRU 26 as described above. In this embodiment, the generator power converter 164 includes a voltage control function 166 and a current control function 167, both of which are configured to facilitate DC / DC conversion. In this embodiment, again, based on the power consumption requirements of the TRU 26, the TRU controller 82 provides command signals represented as 169 and 170 to the voltage control function 166 and the current control function 167, respectively, as further discussed herein. In this embodiment, the voltage control function 166 includes a voltage regulation function and is configured to monitor the output DC voltage from the generator 162 and maintain a constant DC voltage outside of the voltage control function 166 for supply to the DC bus 125 and the power management system 190, and ultimately to the TRU 26. The current control function 167 monitors and transmits to the TRU 26 the state of the current drawn from the generator 162. Again, in an embodiment, the communication may be through a standard communication interface such as CAN, RS-485, etc. Furthermore, as discussed further herein, the communication may be wired or wireless.

[0086] Power Flow

[0087] continue Figure 3 As previously described, the power source interface 120 may include interfaces to various power sources 122 that are managed and monitored by the TRU controller 82. The TRU controller 82 and the power management system 190 manage and determine the flow of electrical power in the power source interface 120 based on the operational requirements of the TRU 26 and the capabilities of the components (e.g., generators 162, converters 164, energy storage devices 152, etc.) in the power source interface 120. The TRU controller determines the status of the various power sources 122, controls their operation, and directs power to and from the various power sources 122, etc., based on the various requirements of the TRU 26.

[0088] In an embodiment, there are five main power flows associated with the power source interface 120 and specifically the DC bus 125 managed by the TRU controller 82 and the power management system 190. First, power supplied to the DC bus 125 via the generator 162 or the generator power converter 164, such as the second DC power 165. Second, power supplied to the DC bus 125 when the DC bus 125 is operably connected to the grid power source 182. Third, power supplied to the DC bus from the energy storage device 152. Fourth, power directed from the DC bus 125 to the energy storage device 152. Finally, DC power directed from the DC bus 125 to the power management system 190 and the TRU 26.

[0089] The power flows will be transmitted through different paths based on the requirements of the power management system 190 and the specific configuration of the power source interface 120. The DC bus 125 and the power management system 190 operate as a central power bus to connect the various power sources 122 together to supply the power requirements of the TRU 26. The TRU controller and power management system 190 control the switching, directing, or redirecting of power to / from the five power flows as needed to meet the power requirements of the TRU 26.

[0090] Now go to 4A to 4H , each of which provides a simplified diagram depicting each of the various possible power flow combinations in the power source interface 120 associated with the DC bus 125 . FIG. 4A to FIG. 4C The power flow of power (e.g., the second DC power) supplied from the generator 162 and / or the generator power converter 164 is depicted. Referring now to Figure 5A In an embodiment, logic employed by the TRU controller 82 for directing power on the DC bus 125 to the power management system 190 determines whether the TRU 26 is operational. If so, and the energy storage system 150 indicates that the energy storage device 120 exhibits a state of charge less than a selected threshold, the power on the DC bus 125 is directed to the power management system 190, and thereby to the TRU 26 and the energy storage system 150, for recharging the energy storage device 152. In an embodiment, priority is given to satisfying the power requirements of the TRU 26. Any remaining power may be directed to a recharging application of the energy storage system 150. It should be recognized that while a specific threshold of 80% is disclosed and used in the described embodiments, such value and description are merely illustrative. Other values ​​and applications of the threshold are possible.

[0091] Now also refer to Figure 4B , which depicts a second example of power flow for power supplied from generator 162 and / or generator power converter 164. In this embodiment, if TRU 26 is operating and energy storage system 150 indicates that energy storage device 152 exhibits a state of charge that exceeds a selected threshold, power on DC bus 125 is directed only to power management system 190 to power only TRU 26 (because energy storage system 150 does not yet need to be recharged). Similarly, in yet another embodiment, as Figure 4C16 and / or generator power converter 164. In this embodiment, the logic employed by TRU controller 82 for directing power to power management system 190 addresses the situation when TRU 26 is not operating and energy storage system 150 indicates that energy storage device 152 exhibits a state of charge less than a selected threshold (100% in this example, although other thresholds are possible). In this embodiment, the DC power on DC bus 125 is directed only to energy storage system 150 for recharging energy storage device 152.

[0092] Now go to FIG. 4D to FIG. 4F , which depicts the power flow of power supplied from the grid power source 182. Figure 4D In the depicted embodiment, the logic employed by the TRU controller 82 for directing power from the grid power source 182 determines whether the TRU 26 is operating and whether the generator 162 (or the generator power converter 164) is not operating. If so, and the energy storage system 150 indicates that the energy storage device 152 exhibits a state of charge less than a selected threshold, power is directed from the DC bus 125 to the power management system 190, and then to the TRU system 26 and the energy storage system 150, for recharging the energy storage device 152. In an embodiment, again, priority is given to satisfying the power requirements of the TRU system 26. Any remaining power may be directed to a recharging application of the energy storage system 150. It should be understood that while a specific threshold of 80% is disclosed and used in the described embodiments, such values ​​and descriptions are merely illustrative. Other values ​​and applications of the threshold are possible.

[0093] Now also refer to Figure 4E , which depicts a second example of power flow for power supplied from grid power source 182 when generator 162 is not operating. In this embodiment, if TRU 26 is operating and energy storage system 150 indicates that energy storage device 152 exhibits a state of charge that exceeds a selected threshold, then the DC power on DC bus 125 is only directed to power management system 190 and to TRU 26 (because energy storage system 150 does not yet need to be recharged). Similarly, in yet another embodiment, as Figure 4F1, a third power flow of power supplied from the grid power source 182 when the generator 162 is not operating is depicted. In this embodiment, the logic employed by the TRU controller 82 for directing power on the DC bus 125 addresses the situation when the TRU 26 is also not operating, and the energy storage system 150 indicates that the energy storage device 152 exhibits a state of charge less than a selected threshold (100% in this example, although other thresholds are possible). In this embodiment, power on the DC bus 125 is directed only to the energy storage system 150 for recharging the energy storage device 152. In an embodiment, the power requirements of the energy storage system 150 are met with priority.

[0094] Now go to Figure 4G and Figure 4H , which depicts the power flow of power also supplied from the energy storage system 150 to the power management system 190 and the TRU 26 under selected conditions for operation. Figure 4G , the power flow to the TRU 26 is provided from the generator 162 and / or the generator power converter 164 (e.g., the second DC power 165) and from the energy storage system 150. In an embodiment, the logic employed by the TRU controller 82 for directing power to the DC bus 125 and the power management system 190 determines whether the TRU 26 is operating. If so, and the energy storage system 150 indicates that the energy storage device 152 exhibits a state of charge greater than a selected threshold, power from both the generator 162 (or the generator power converter 164) and the energy storage system 150 is directed to the DC bus 125, and then to the power management system 190 and thereby the TRU 26. In an embodiment, a threshold of 10% is employed for the state of charge of the energy storage device 152. In this embodiment, power is provided by the energy storage system 150, and thereby the energy storage device 152 is discharged. In an embodiment, the power requirements of the TRU 26 are met with priority. This embodiment may be employed under conditions where the output power of the generator 162 and / or the generator power converter 164 is less than the power required to operate the TRU 26. It should be appreciated that while a specific threshold of 10% is disclosed and used for the described embodiments, such values ​​and descriptions are merely illustrative. Other values ​​and applications of the threshold are possible. For example, in some cases, it may be desirable to prioritize the operation of the TRU 26 so that completely draining the energy storage device 152 is acceptable. Likewise, in other embodiments, it may be desirable to modify the functionality of the TRU 26 or curtail its operation to avoid excessive discharge of the energy storage device 152.

[0095] Now also refer to Figure 4H, which depicts a second example of power flow from the energy storage system 150 only. In this embodiment, if the TRU 26 is operating, but the generator 162 and / or the generator power converter 164 are not operating, if the energy storage system 150 indicates that the energy storage device 152 exhibits a state of charge that exceeds a selected threshold, the power on the DC bus is directed to the power management system 190, which then provides power to the TRU 26. In an embodiment, a 10% threshold is used for the state of charge of the energy storage device 152. In this embodiment, power is provided by the energy storage system 150, and the energy storage device 152 is therefore discharged. In an embodiment, the power requirements of the TRU 26 are met with priority. Again, this embodiment can be employed under conditions where the output power of the generator 162 and / or the generator power converter 164 is less than the power required to operate the TRU 26. It should be recognized that although a specific threshold of 10% is disclosed and used in the described embodiments, such values ​​and descriptions are merely illustrative. Other values ​​and applications of the threshold are possible. For example, in some cases, it may be desirable to prioritize the operation of TRU 26 so that it is acceptable to completely drain energy storage device 152. Likewise, in other embodiments, it may be desirable to modify the functionality of the TRU or scale back its operation to avoid over-discharging energy storage device 152.

[0096] return Figure 3, in another embodiment, and a dedicated operating mode and power flow for the TRU system 26 and the power source interface 120. In this embodiment (referred to as a fail-operation or "limp home" mode), the power source interface 120 is configured so that in the selected operating mode, power is directed from the tractor or vehicle 22 to the TRU 26. In an embodiment, if the energy storage device 152 exhibits an SOC below a selected threshold (e.g., <10%), and the generator 162 / generator power converter 164 is not operable, but the TRU system 26 is operable and requires power, then the TRU power may be drawn from the tractor or truck's power system. (i.e., tethered to the energy storage device or generator of the tractor / truck). In addition, it should be recognized that the described embodiments, while generally directed to the generator 162 mounted on the trailer portion of the vehicle 22, such description is merely illustrative. In another embodiment, the generator 162 or another generator may be mounted at the wheel hub or axle of the tractor portion of the vehicle 22 without loss of generality and still fully applicable to the described embodiments. In an embodiment, tractor / truck power may be sent to the power source interface 120 via the grid plug 189. Alternatively, a connection may be made between the grid power source 182 and the vehicle power. For example, in operation, when the vehicle 22 trailer is in operation, such as at a delivery, the grid plug 189 will be plugged into the electric PTO of the tractor / trailer and act as a mobile grid source. The TRU controller 82 will be programmed to determine whether the grid plug is active, and if so, to draw power (or supplement generator power) only when the energy storage device SOC is below a threshold, as an alternative to modifying the functionality of the TRU system 26 or curtailing its operation.

[0097] Now go to FIG. 5A to FIG. 5H , FIG. 5A to FIG. 5H Various possible configurations of the power source interface 120 are depicted. Figure 5A Depicted is a simplified block diagram of a power source interface 120 as described herein. Figure 5A A single DC bus 125 is depicted in a variable configuration. Figure 5B An alternative embodiment of the power source interface 220 as described above is depicted. In this embodiment, the DC bus is split into a variable side 125b between the energy storage device 152 and the DC / DC converter 156 and a fixed DC bus 125, 125a on the output side of the DC / DC converter 156 of the energy storage system 150.

[0098] Figure 5C Depicted is a simplified block diagram of a power source interface 320 according to another embodiment as described herein. Figure 5CDepicts the configuration of a power source interface 320, wherein a grid power source 182 and a grid power converter 184 are typically connected to an energy storage device 152 on a DC bus 125b in a variable configuration. In this embodiment, a DC / DC converter 156 isolates the variable DC bus 125b from a fixed DC bus 125a, which includes the output of the DC / DC converter 156 of the energy storage system 150 and the output of the generator power converter 164, which are typically connected to a DC / AC converter 192 of a power management system 190 to provide power to the TRU system 26.

[0099] Similarly, Figure 5D Depicted is a simplified block diagram of a power source interface 420 according to yet another embodiment as described herein. Figure 5D Depicts the configuration of a power source interface 420, wherein a grid power source 182 and a grid power converter 184 are typically connected to the output of a generator 162 and a generator power converter 164 and an energy storage device 152 on a DC bus 125b in a variable configuration. In this embodiment, a DC / DC converter 156 isolates the variable DC bus 125b from a fixed DC bus 125a, which includes the output of the DC / DC converter 156 of the energy storage system 150, which is typically connected to a DC / AC converter 192 of a power management system 190 to provide power to the TRU system 26.

[0100] same, Figure 5E Depicted is a simplified block diagram of a power source interface 520 according to yet another embodiment as described herein. Figure 5E Depicts a configuration of a power source interface 520 in which a grid power source 182 and a grid power converter 184 are connected in series with a DC / DC converter 156, forming a fixed DC bus, indicated as 125c, between the grid power converter and the DC / DC converter 156 of the energy storage system 150. In this embodiment, the DC / DC converter 156 isolates the fixed DC bus 125c from the variable DC bus 125a. The output of the generator 162 and the generator power converter 164, along with the energy storage device 152, are connected to the DC / AC converter 192 of the power management system 190 on the variable DC bus 125a in a variable configuration to provide power to the TRU system 26.

[0101] same, Fig. 5F Depicted is another simplified block diagram of a power source interface 620 according to yet another embodiment as described herein. Fig. 5FDepicting the configuration of the power source interface 620, wherein the grid power source 182 and grid power converter 184 and the output of the generator 162 and generator power converter 164 are connected to the DC / DC converter 156, forming a fixed DC bus, again indicated as 125c. Again, the DC / DC converter 156 of the energy storage system isolates the fixed DC bus 125c from the variable DC bus 125a. In addition, the output of the DC / DC converter 156 of the energy storage system 150, along with the energy storage device 152, is connected to the DC / AC converter 192 of the power management system 190 on the variable DC bus 125a in a variable configuration to provide power to the TRU system 26.

[0102] same, Figure 5G Depicted is a simplified block diagram of a power source interface 720 according to yet another embodiment as described herein. Figure 5G Depicting the configuration of the power source interface 720, wherein the output of the generator 162 and the generator power converter 164 are connected to the energy storage device 152 on a variable DC bus 125a in a variable configuration. The DC / DC converter 156 of the energy storage system forms a fixed DC bus, again indicated as 125c, which again isolates the fixed DC bus 125c from the variable DC bus 125a. In addition, the output of the DC / DC converter 156 of the energy storage system 150 is connected to the fixed DC bus 125c along with the grid power converter 184 to provide power to the DC / AC converter 192 of the power management system 190 to provide power to the TRU system 26.

[0103] at last, Figure 5H Depicted is a simplified block diagram of a power source interface 820 according to yet another embodiment as described herein. Figure 5G Depicting the configuration of the power source interface 820, wherein the generator 182 is connected to the generator power converter 184 to the fixed voltage DC bus 125c. The grid power source 182 is connected to the energy storage device 152 on the variable DC bus 125a in a variable configuration via the output of the grid power converter 184. The DC / DC converter 156 of the energy storage system 150 is connected to the generator power converter 164 on the fixed DC bus 125c. Again, the DC / DC converter 156 isolates the fixed DC bus 125c from the variable DC bus 125a. In addition, the output of the DC / DC converter 156 of the energy storage system 150 is connected to the variable DC bus 125a along with the energy storage device 152 and provides power to the DC / AC converter 192 of the power management system 190 to provide power to the TRU system 26.

[0104] The TRU 26 may also include a renewable power source 110 ( Figure 1) configured to recharge the battery of the energy storage device 152. One embodiment of the renewable power source 110 may be a solar panel mounted, for example, to the exterior of the top wall 30 of the cargo bed 24 (see also Figure 1 ). For example, the renewable power source 110 may generate all or part of the low voltage DC power required by the TRU controller 82. Again, such a configuration simplifies the wiring and routing of the system design by eliminating additional DC cable sets from the energy storage device 152 over the HV cables to the AC / DC converter 156.

[0105] When compared to more traditional systems, the benefits of the present disclosure include no fuel delivery, fuel system and fuel consumption, as well as a refrigeration unit that emits less noise and no combustion byproducts. In addition, the present disclosure includes an energy storage device that is conveniently and efficiently recharged to meet the power needs of the refrigeration unit.

[0106] As described above, embodiments may be in the form of processor-implemented processes and devices (such as processors) for practicing these processes. Embodiments may also be in the form of computer program code, which includes instructions implemented in tangible media such as network cloud storage, SD card, flash drive, floppy disk, CD ROM, hard drive, or any other computer-readable storage medium, wherein, when the computer program code is loaded into a computer and executed by the computer, the computer becomes a device for practicing the embodiments. Embodiments may also be in the form of computer program code, for example, whether stored in a storage medium, loaded into a computer and / or executed by a computer, or transmitted through some transmission media, loaded into a computer and / or executed by a computer, or transmitted through some transmission media, such as by wires or cables, by optical fiber, or via electromagnetic radiation, wherein, when the computer program code is loaded into a computer and executed by a computer, the computer becomes a device for practicing the embodiments. When executed on a general-purpose microprocessor, the computer program code segment configures the microprocessor to create a specific logic loop.

[0107] The term "about" is intended to include the degree of error associated with measurement of a particular quantity based on the equipment available at the time the application was filed. For example, "about" may include a range of ±8% or 5%, or 2% of a given value.

[0108] The terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the terms "comprises" and / or "comprising" when used in this specification indicate the presence of the recited features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements and / or groups thereof.

[0109] Although the present disclosure is described with reference to one or more exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and equivalents may be substituted for its elements without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt specific situations or materials to the teachings of the present disclosure without departing from its basic scope. Therefore, it is intended that the present disclosure is not limited to the specific embodiments disclosed as the best mode contemplated for carrying out the present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.

Claims

1. A power system architecture for powering a transport refrigeration system, comprising: a transport refrigeration unit (TRU) operable in a vapor compression cycle, the TRU having a compressor configured to compress a refrigerant, an evaporator heat exchanger operatively coupled to the compressor, an evaporator fan configured to provide a return airflow from a return air inlet and flow the return airflow over the evaporator heat exchanger, the TRU further comprising a TRU controller configured to execute a process for determining an AC power requirement of the TRU; a generator power converter configured to receive generator three-phase alternating current (AC) power from an AC generator operably coupled to the axle or hub and configured to provide the generator three-phase AC power and to provide generator DC power; a grid power converter configured to receive the grid three-phase AC power from a grid power source operable to provide grid three-phase AC power; the grid power converter operable to provide grid DC power; an energy storage device operable to provide DC power and connected to the variable DC bus; a power management system operably connected to direct power to the TRU based at least in part on at least the AC power requirement; A DC / DC converter is operably connected to the variable DC bus, the DC / DC converter being configured to convert variable DC power to fixed DC power on a fixed DC bus and convert at least a portion of the DC power on the fixed DC bus to supply the variable DC bus.

2. The power system architecture according to claim 1, characterized in that: The generator power converter is configured to receive a first three-phase alternating current (AC) power provided by the AC generator and transmit generator DC power to one of a fixed DC bus or a variable DC bus.

3. The power system architecture according to claim 1, characterized in that: The generator power converter comprises 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.

4. The power system architecture according to claim 1, characterized in that: The generator power converter includes a voltage control function and a current control function, wherein at least the voltage control function is at least partially responsive to the AC power requirement.

5. The power system architecture according to claim 1, characterized in that: The grid power converter is configured to receive a first three-phase AC power provided by the grid power source and transmit grid DC power to one of a fixed DC bus or a variable DC bus.

6. The power system architecture according to claim 1, characterized in that: The grid power converter comprises 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.

7. The power system architecture according to claim 1, characterized in that: The grid power converter includes a voltage control function and a current control function, wherein at least the voltage control function is at least partially responsive to the AC power demand.

8. The power system architecture according to claim 1, characterized in that: An energy storage system includes an energy storage device and at least one of a first energy storage system DC / DC converter configured to provide 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 DC power on the fixed DC bus to supply the variable DC bus and the energy storage device.

9. The power system architecture according to claim 8, characterized in that: Also included is 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.

10. The power system architecture according to claim 9, characterized in that: The energy storage system DC / DC converter and the second energy storage system DC / DC converter are integrated, and wherein the first energy storage system DC / DC converter is operably connected to the TRU controller and is configured to direct power flow to the fixed DC bus and the power management system and from the fixed DC bus to the variable DC bus based on at least one of the AC power demand and the state of charge of the energy storage device.

11. The power system architecture according to claim 1, characterized in that: The energy storage device includes at least one of a battery, a fuel cell, and a flow battery.

12. The power system architecture according to claim 1, characterized in that: The power management system is configured to receive DC power from one of the fixed DC bus and the variable DC bus and provide a second three-phase AC power to the TRU based at least on the AC power requirement.

13. The power system architecture according to claim 12, characterized in that: 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.

14. The power system architecture according to claim 1, characterized in that: The grid power converter, generator power converter, energy storage device, and power management system are operably connected to the variable DC bus.

15. The power system architecture according to claim 1, characterized in that: The grid power converter, generator power converter, 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.

16. The power system architecture according to claim 1, characterized in that: 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.

17. The power system architecture according to claim 1, characterized in that: The grid power converter, the generator power converter, the energy storage system DC / DC converter, and the 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.

18. The power system architecture according to claim 1, characterized in that: The grid power converter, power management system, 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.

19. The power system architecture according to claim 1, characterized in that: 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, the energy storage device and the power management system are operably connected to the variable DC bus.

20. The power system architecture according to claim 1, characterized in that: The grid power converter and 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, the energy storage device, and the power management system are operably connected to the variable DC bus.

21. The power system architecture according to claim 1, characterized in that: 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.

22. The power system architecture according to claim 1, characterized in that: Also included is a return air temperature (RAT) sensor disposed in the return airflow and configured to measure a temperature of the return airflow, the RAT sensor being operably connected to the TRU controller, the TRU controller being configured to execute a process of determining the AC power requirement of the TRU based at least in part on the RAT.

23. A method of generating power and directing the power to a transport refrigeration unit (TRU) having: a compressor configured to compress a refrigerant; an evaporator heat exchanger operatively coupled to the compressor; an evaporator fan configured to provide a return air flow from a return air inlet and to flow the return air flow over the evaporator heat exchanger; and a TRU controller operable to perform the method, the method comprising: determining an AC power requirement of the TRU; providing generator DC power from a generator power converter operably connected to an alternating current (AC) generator operably connected to the axle or hub; providing grid DC power from a grid power converter operatively connected to a grid power source providing grid three-phase AC power; providing DC power to the power management system from a variable DC bus, the variable DC bus being operatively connected to an energy storage device, a DC / DC converter operatively connected to the variable DC bus configured to convert the variable DC power to fixed DC power on a fixed DC bus and convert at least a portion of the DC power on the fixed DC bus to supply the variable DC bus; Three-phase AC power is directed to the TRU by a power management system operatively connected to the TRU, the directing being based at least in part on the AC power requirement.

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