Solar power assisted transport refrigeration systems, transport refrigeration units and methods for same

CROSS-REFERENCE TO RELATED APPLICATION

p-0002This application claims priority to U.S. Provisional Patent Application Ser. No. 61/299,827 entitled “Solar Power Assisted Transport Refrigeration Systems, Transport Refrigeration Units and Methods for Same” filed on Jan. 29, 2010. The content of this application is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

p-0003This invention relates generally to the field of transport refrigeration systems and methods of operating the same, and more particularly to the integration of disparate power sources or energy storage device.

BACKGROUND OF THE INVENTION

p-0004Transport refrigeration systems such as containers, truck, trailer, and bus, depend on fossil-fuel driven prime movers to provide the electrical energy needed to run the components of the transport refrigeration system. This fuel consumption is over and above what is required to operate the vehicle and becomes a significant added cost of operation. Solar panels have been used to support truck refrigeration. However, these related art systems manually switch between a fuel driven engine and the solar panel to separately provide the energy to the transport refrigeration system and required extra container insulation and downsizing of the original equipment to which the solar power is being applied to, which leads to either a performance penalty or a higher initial cost due to redesign or both.

SUMMARY OF THE INVENTION

p-0005Perishable items must be maintained within a temperature range to reduce or prevent, depending on the items, spoilage, or conversely damage from freezing during transport. A transport refrigeration unit is used to maintain proper conditions within a transport cargo space. The transport refrigeration unit can regulate conditioned air delivery by the transport refrigeration unit to a container or the transport cargo space. The transport refrigeration unit can be under the direction of a controller that can operate a transport refrigeration system including a power management capability.

p-0006In view of the background, one aspect of the application is to provide a novel power system configuration, management, and methods for same for a transport refrigeration system.

p-0007In view of the background, it is an object of the application to provide a transport refrigeration system, transport refrigeration unit, and methods of operating same that can ensure real-time allocation from integrated solar power into the refrigeration system, both as a function of load or demand, and/or solar energy availability.

p-0008Embodiments of power management configurations and control architectures can integrate solar power into the electrical system of a transport refrigeration system.

p-0009Embodiments of power management systems and methods can integrate solar power into the electrical system of a transport refrigeration system to ensure real-time allocation of energy from disparate power sources into the refrigeration system, both as a function of load or demand, as well as of solar energy availability.

p-0010Embodiments of power management system can integrate solar power into the electrical system of a transport refrigeration system with no loss of functionality to the container during maintenance or shipping and handling of the container.

p-0011Embodiments of power management system can combine solar power into the electrical system of a transport refrigeration system and use peak power tracking to integrate use of the solar generated power.

p-0012In one embodiment, solar fabrics are used and attached to surfaces of the container or trailer body to allow removal and re-installation depending on operational needs (e.g., in the field).

p-0013One embodiment according to the application can include a control module for a transport refrigeration system for controlling an improved all-electric transport refrigeration system that receives its compressor drive motor power and all other electrical power concurrently from a combination of a solar photovoltaic (PV) system and fossil fuel driven prime movers.

p-0014One embodiment of a transport refrigeration system according to the application can include a power control module to control concurrent supply of electrical energy from a solar PV system, an engine driven generator, and batteries.

p-0015In an aspect of the invention, a transport refrigeration system can include a compressor; a first electric motor that provides a motive force to the compressor; at least one fan; a second electric fan motor that provides a motive force to the fan; a solar PV electrical power source; a battery electrical power source; a engine driven generator electrical power source; and a power management controller coupled to route power selectively and concurrently from two of the electrical power sources to provide electrical power to the first motor and the second motor.

BRIEF DESCRIPTION OF THE DRAWINGS

p-0016Novel features that are characteristic of exemplary embodiments of the invention are set forth with particularity in the claims. Embodiments of the invention itself may be best understood, with respect to its organization and method of operation, with reference to the following description taken in connection with the accompanying drawings in which:

p-0017<figref idrefs="DRAWINGS">FIG. 1</figref> is diagram that schematically illustrates an exemplary transport refrigeration system having a compressor with an integrated electric drive motor powered by an electrical power system designed according to embodiments of the application;

p-0018<figref idrefs="DRAWINGS">FIG. 2</figref> is diagram that illustrates a power control apparatus for a transport refrigeration system according to embodiments of the application;

p-0019<figref idrefs="DRAWINGS">FIG. 3</figref> is a diagram that illustrates an exemplary embodiment of a power management system for a transport refrigeration system according to the application;

p-0020<figref idrefs="DRAWINGS">FIG. 4</figref> is a diagram that illustrates another exemplary embodiment of a power management system for a transport refrigeration system according to the application;

p-0021<figref idrefs="DRAWINGS">FIG. 5</figref> is a diagram that illustrates another exemplary embodiment of a power management system for a transport refrigeration system according to the application;

p-0022<figref idrefs="DRAWINGS">FIG. 6</figref> is a diagram that shows an exemplary power output characteristics of solar PV films;

p-0023<figref idrefs="DRAWINGS">FIG. 7</figref> is a diagram that illustrates an exemplary embodiment of a solar film mounting platform affixed to a container according to the application; and

p-0024<figref idrefs="DRAWINGS">FIG. 8</figref> is a diagram that illustrates another exemplary embodiment of a power management system for a transport refrigeration system according to the application.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

p-0025Reference will now be made in detail to exemplary embodiments of the application, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts.

p-0026Transportation refrigeration systems can be offered in diverse architectures, for example, for use with trucks, truck-trailers, and containers. Refrigerant vapor compression systems used in connection with transport refrigeration systems are generally subject to more stringent operating conditions than in air conditioning or commercial refrigeration applications due to the wide range of operating load conditions and the wide range of outdoor ambient conditions over which the refrigerant vapor compression system must operate to maintain product within the cargo space at a desired temperature. The desired temperature at which the cargo needs to be controlled can also vary over a wide range depending on the nature of cargo to be preserved. The refrigerant vapor compression system must not only have sufficient capacity to rapidly pull down the temperature of product loaded into the cargo space at ambient temperature, but also operate efficiently at low load when maintaining a stable product temperature during transport. Additionally, transport refrigerant vapor compression systems are subject to cycling between an operating mode and standstill mode, e.g., an idle state.

p-0027<figref idrefs="DRAWINGS">FIG. 1</figref> is a diagram that shows an exemplary embodiment of a transport refrigeration system. Referring to <figref idrefs="DRAWINGS">FIG. 1</figref>, a trailer refrigeration system <b>20</b> is schematically illustrated with a compressor <b>22</b>. A compressing mechanism <b>24</b>, an electric compressor motor <b>26</b> and an interconnecting drive shaft <b>28</b> are all sealed within a common housing of the compressor <b>22</b>. In one example, the compressor <b>22</b> is a variant of a 06D compressor manufactured by Carrier Corporation.

p-0028A power management system <b>40</b> that is capable of fully powering the internal electric motor <b>26</b> of the compressor preferably also provides power to satisfy the electrical requirements of other portions of the system <b>20</b> as will be explained. For example, the power management system <b>40</b> can integrate a plurality of disparate power sources into the system <b>20</b>. In one embodiment, the power sources can include a solar PV system, batteries, and fuel driven prime movers (e.g., diesel engines). A controller <b>42</b>, which may be a commercially available microprocessor, can be used to control power usage in the system <b>20</b> or incorporated into the power management system <b>40</b>.

p-0029Operations of the refrigeration system <b>20</b> can be described starting at the compressor <b>22</b>, where the refrigerant enters the compressor and is compressed to a higher temperature and pressure. Refrigerant gas then moves into the air-cooled condenser <b>44</b>. Air flowing across a group of condenser coil fins and tubes <b>46</b> can cool the gas to its saturation temperature. The air flow across the condenser can be energized by a condenser fan assembly <b>50</b> having two fans. The illustrated example includes fan <b>52</b>, electrical condenser fan motor <b>54</b> and fan <b>56</b> having electrical motor <b>58</b>. The controller <b>42</b> can regulate power supply to the fan motors <b>54</b>, <b>58</b>.

p-0030By removing latent heat, the gas can condense to a high pressure/high temperature liquid and flow to a receiver <b>60</b> that provides storage for excess liquid refrigerant during low temperature operation. From the receiver <b>60</b>, the liquid refrigerant can pass through a subcooler heat exchanger <b>64</b>, through a filter dryer <b>66</b> that can keep the refrigerant cool and dry, then to a heat exchanger <b>68</b> that can increase the refrigerant subcooling, and then pass to a thermostatic expansion valve <b>70</b>.

p-0031As the liquid refrigerant passes through the expansion valve <b>70</b>, some of it vaporizes into a gas. Return air from the refrigerated space flows over the heat transfer surface of an evaporator <b>72</b>. As refrigerant flows through tubes <b>74</b> in the evaporator <b>72</b>, the remaining liquid refrigerant absorbs heat from the return air, and in so doing, can be vaporized. The air flow across the evaporator can be energized by an evaporator fan assembly <b>80</b>. The illustrated example includes three fans <b>82</b>, <b>84</b> and <b>86</b> that are respectively powered by electric fan motors <b>88</b>, <b>90</b>, and <b>92</b>. The fan motors <b>88</b>, <b>90</b> and <b>92</b> can receive their electrical power from the power management system <b>40</b>. The controller <b>42</b> can control the consumption of power and operations of the fan motors <b>88</b>, <b>90</b>, <b>92</b> of the evaporator fan assembly.

p-0032Refrigerant vapor can flow through a suction modulation valve <b>100</b> back to the compressor <b>22</b> and integral drive motor <b>26</b>. A thermostatic expansion valve bulb or sensor can be located on the evaporator outlet tube. The bulb can control the thermostatic expansion valve <b>70</b>, to control refrigerant super-heating at the evaporator outlet tubing.

p-0033Exemplary embodiments of transport refrigeration systems integrate three energy systems: the generator for pull-down and off-solar operation, the solar films, and the battery system. Each of these energy sources has a distinct set of power characteristics that need to be conditioned before being fed between each other, or to the loads. The generator puts out 3-phase AC, while the solar PV and the battery produce DC power. The power management system <b>40</b> can actively manage these energy sources to ensure performance, reliability, availability and/or energy efficiency. In one embodiment, inclusion of a storage system, which can be selected using a trade-off between weight, cost, and size, can provide dual functionality of capturing solar energy in excess of load, as well as a source for starting up the generator's engine.

p-0034Exemplary connections of the power management system <b>40</b> are shown in <figref idrefs="DRAWINGS">FIG. 2</figref>. As shown in <figref idrefs="DRAWINGS">FIG. 2</figref>, the power management system <b>40</b> can transfer and receive power from generator <b>210</b>, receive power from solar PV system <b>220</b>, transfer and receive power from storage <b>230</b> (e.g., battery). The power management system <b>40</b> can transmit and receive control signals to and from the generator <b>210</b>, the solar PV system <b>220</b>, and the electrical energy storage <b>230</b>.

p-0035The power management system <b>40</b> can controllably provide electrical energy for a dynamic load <b>250</b> of the transport refrigeration unit. The load <b>250</b> can include the AC driven and DC driven components. The power management system <b>40</b> can supply the power needed for the electrical motors associated with the compressor <b>22</b>, condenser fan assembly <b>50</b>, and the evaporator fan assembly <b>80</b>.

p-0036Exemplary power electronic architectures for the embodiments of power management systems are shown in <figref idrefs="DRAWINGS">FIGS. 3-5</figref>. An exemplary embodiment of a power controller is shown in <figref idrefs="DRAWINGS">FIG. 3</figref>. As shown in <figref idrefs="DRAWINGS">FIG. 3</figref>, power management system and controller <b>340</b> is electrically coupled to engine driven generator <b>310</b>, solar PV system <b>320</b> and electric energy source <b>330</b> (e.g., rechargeable battery, capacitor, super capacitor).

p-0037The power management system and controller <b>340</b> can connect the generator <b>310</b> to provide power to the components of the transport refrigeration unit. The generator <b>310</b>, compressor <b>352</b> (e.g., drive motor), battery charger <b>344</b>, and also optional additional electrically powered components <b>356</b> are connected to an AC power bus. Exemplary additional components <b>356</b> can include sensors (e.g., temperature sensors), valves (e.g., expansion valve, solenoid valves), and the like. Driven by controller <b>342</b>, the generator <b>310</b> can supply AC power to battery charger <b>344</b> and AC electricity to the compressor. Controller <b>346</b> can be connected to a DC power bus between the solar PV system <b>320</b> and DC powered fans <b>354</b> and between the electric energy source <b>330</b> and the DC powered fans <b>354</b>. In one embodiment, the DC power bus can operate between 24 volts DC and 48 volts DC. As shown in <figref idrefs="DRAWINGS">FIG. 3A</figref>, the DC/DC converter can manage the energy flows from solar power and the electric energy source to the DC fans <b>354</b>. The power management system and controller <b>340</b> has a low cost implementation that can integrate the solar power for selected components of the transport refrigeration unit (e.g., the DC fans <b>354</b>) through a DC bus.

p-0038An exemplary embodiment of a power controller is shown in <figref idrefs="DRAWINGS">FIG. 4</figref>. As shown in <figref idrefs="DRAWINGS">FIG. 4</figref>, power management system and controller <b>440</b> is electrically coupled to generator <b>310</b>, solar PV system <b>320</b> and electric energy source <b>330</b> (e.g., rechargeable battery).

p-0039The power management system and controller <b>440</b> can connect the generator <b>310</b>, the solar PV system <b>320</b>, and electric energy source <b>330</b> to an AC power bus coupled to components of the transport refrigeration unit. The generator <b>310</b> is connected to the compressor <b>24</b>, AC fans and also optional additional electrically powered components <b>356</b>. Driven by controller <b>442</b>, the generator <b>310</b> can supply AC power to single phase loads (e.g., fans) and three phase loads (e.g., the compressor <b>24</b>). Controller <b>444</b> is connected between the solar PV system <b>320</b> and load (single phase load) representing the transport refrigeration unit. Controller <b>446</b> is connected between the electric energy source <b>330</b> and the single phase load. The controllers <b>444</b>, <b>446</b> can include DC/AC converters to convert the DC to AC to enable the fans to retain AC motors and can synchronize the power and levels between the three sources. For example, additional electrically powered components <b>356</b> can include additional single phase AC load, a three phase AC load, or any DC load (e.g., additional fans/compressor, additional heating system).

p-0040As shown in <figref idrefs="DRAWINGS">FIG. 4</figref>, the power management system and controller <b>440</b> requires little change in the load hardware. The power management system and controller <b>440</b> retains the AC motors for the fans, and enables single-phase and 3-phase loads as needed. The power management system and controller <b>440</b> can perform field matching and power matching between power supplied by different sources before it can be provided to the transport refrigeration unit. Such conditioning can be performed by hardware (e.g., inverters) and/or software (e.g. using a processor or controller). However, the power management system and controller <b>440</b> provides AC power only from the transport refrigeration unit side, in contrast to the two different power modes as shown in <figref idrefs="DRAWINGS">FIG. 3</figref>.

p-0041An exemplary embodiment of a power controller is shown in <figref idrefs="DRAWINGS">FIG. 5</figref>. As shown in <figref idrefs="DRAWINGS">FIG. 5</figref>, power management system and controller <b>540</b> is electrically coupled to generator <b>310</b>, solar PV system <b>320</b> and electric energy source <b>330</b> (e.g., battery).

p-0042The power management system and controller <b>540</b> can selectively connect between each of the generator <b>310</b>, the solar PV system <b>320</b>, and the electric energy source <b>330</b> and can provide a connection to the load represented by the transport refrigeration system <b>200</b> (e.g., the single phase load and three phase load). Driven by controller <b>540</b>, the three power sources can supply AC power to single phase loads (e.g., fans) and three phase loads (e.g., the compressor <b>24</b>). The power management system and controller <b>540</b> can have an integrated power system with optimized controllers that can be designed for additional functionality. The power management system and controller <b>540</b> control the engine-generator starter and can control variable speed compressors and fans.

p-0043In one embodiment, power management system and controller <b>540</b> can include a dedicated power unit to include a single converter to integrate connected energy sources for power management. The converter can interface directly with all the generator <b>310</b>, the solar PV system <b>320</b>, and the electric energy source <b>330</b> to output single three phase AC output. In this embodiment, the power management system and controller <b>540</b> can replace the plurality of converters (e.g., DC/DC converters, DC/AC converters) previously needed, which can be cost effective and can reduce complexity of the control required for multiple converters. Further, the dedicated power unit can ensure the voltage at output on R, S, T has fixed voltage and fixed frequency regardless of variation of variation of voltage and frequency at generator. Accordingly, control of generator can be reduced and/or greater engine variation can be accepted to reduce overall consumption. Also, the engine could be driven at greater efficiency levels less dependent of fluctuations of the load.

p-0044In one embodiment, power management system and controller <b>540</b> can include a power transfer panel to transfer loads (e.g., automatically) between the additional power sources (<b>320</b> and <b>330</b>) and the generator <b>310</b> (engine). The transfer panel for the power management system and controller <b>540</b> can monitor the solar PV set power and/or the electric energy source/battery set available energy. When the solar PV set power and/or the battery set state of charge is unsatisfactory (e.g., under-voltage monitoring on each power source, low battery state of charge, power source failure), the power management system and controller <b>540</b> can switch or transfer the load to the generator (e.g., can initiate start-up of the engine-generator). The transfer panel for the power management system and controller <b>540</b> can immediately sense when the solar PV set power and/or the electric energy source/battery set power is restored to can switch or transfer the load from the generator. Exemplary load transfers can include partial or complete. The load transfer can include selected components only (e.g., fans). The load transfer can include single phase load transfer.

p-0045Table 1 compares the three embodiments for the power management system and controller <b>340</b>, <b>440</b>, <b>540</b>.

p-0046<tables id="TABLE-US-00001" num="00001"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="1"><colspec colname="1" colwidth="217pt" align="center" /><thead><row><entry namest="1" nameend="1" rowsep="1">TABLE 1</entry></row></thead><tbody valign="top"><row><entry namest="1" nameend="1" align="center" rowsep="1" /></row><row><entry>Comparison of Exemplary Architectures</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="offset" colwidth="14pt" align="left" /><colspec colname="1" colwidth="49pt" align="left" /><colspec colname="2" colwidth="77pt" align="center" /><colspec colname="3" colwidth="77pt" align="left" /><tbody valign="top"><row><entry /><entry>Concept</entry><entry>Compressor</entry><entry /></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="6"><colspec colname="offset" colwidth="14pt" align="left" /><colspec colname="1" colwidth="49pt" align="left" /><colspec colname="2" colwidth="28pt" align="left" /><colspec colname="3" colwidth="56pt" align="center" /><colspec colname="4" colwidth="21pt" align="left" /><colspec colname="5" colwidth="49pt" align="center" /><tbody valign="top"><row><entry /><entry>Architecture</entry><entry>Power</entry><entry>Solar Driven</entry><entry>Fans</entry><entry>Extras</entry></row><row><entry /><entry namest="offset" nameend="5" align="center" rowsep="1" /></row><row><entry /><entry>FIG. 3</entry><entry>AC</entry><entry>N</entry><entry>DC</entry><entry>N</entry></row><row><entry /><entry>FIG. 4</entry><entry>AC</entry><entry>N</entry><entry>AC</entry><entry>N</entry></row><row><entry /><entry>FIG. 5</entry><entry>AC</entry><entry>Y</entry><entry>AC</entry><entry>Y</entry></row><row><entry /><entry namest="offset" nameend="5" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

p-0047Exemplary engines used for generators can be operated inefficiently because the desired power output is constantly changing in response to needs of the transport refrigeration unit (e.g., to maintain a constant temperature in a corresponding). In one embodiment, the power management system can size the incorporated storage system like a battery set so that the engine can operate (e.g., always) at a steady condition or at least a much more predictable condition and/or reduce an amount of bouncing around or changing speeds/power level. Accordingly, the power management system can control whenever there is excess power it goes to store the excess electric energy for example in storage such as a battery and likewise, when there is insufficient power, the deficit can be drawn from storage or solar PV system. In one embodiment, the engine can be operated at a constant speed or peak efficiency point or RPM.

p-0048Embodiments of transport refrigeration systems and methods for same can integrate and provide concurrent use of the solar energy and/or the solar PV system <b>220</b>. Electrical characteristics of solar PV films have power output that increases linearly with voltage up to a peak <b>610</b> as shown in <figref idrefs="DRAWINGS">FIG. 6</figref>. Beyond the peak <b>610</b>, the output can drop rapidly. To increase utilization of the solar energy, and therefore increase or maximize fuel savings to the transport refrigeration systems, the power management controller needs to operate the solar PV system <b>220</b> at (or near and preferably before) the peak power point. Accordingly, in one embodiment, the power management system <b>40</b> (e.g., <b>540</b>) can implement a maximum point tracking (e.g., solar power peak tracking) for the solar PV system to adjust the current and/or electrical energy drawn from the solar film to cause the solar PV system <b>220</b> to follow peak output under varying irradiance and load conditions.

p-0049In situations when portions of the solar film are obscured (for example, under spotty clouds) or are otherwise compromised, the solar energy usage can still be increased or maximized by incorporating a health-monitoring system in the power management controller. For example, the power management system <b>40</b> can be designed to monitor the health and output of the solar films, and dynamically adjust the power drawn from the healthiest and/or highest output sections of the solar film to be different from the power drawn from damaged (permanent modification) or obscured (temporary modification) portions of the solar film. In one embodiment, the solar film can have modular unit construction to remove (e.g., electrically isolate) damaged portions from the solar PV system.

p-0050In one embodiment, the power management system and controller can use the storage to primarily drive the control priority. For example, the power management system and controller <b>540</b> can prioritize electrical energy sources or storage (e.g., battery usage and/or lifetime), over control for the solar PV system or generator. In one embodiment, operations for battery lifetime and overall reduced power consumption can provide control requirements for the power management system and controller. Battery lifetime can be increased differently by type of battery, but an exemplary battery can have increased of maximum lifetime with charge levels between 40-60% or 25-75% (e.g., NiMH), which can provide secondary control requirements for the generator and solar PV system that can be implemented using exemplary converters. One exemplary energy management control can always keep selected battery control conditions (e.g., when to charge and withdraw electrical energy), then receive solar PV power at the controlled or maximum amount that does not conflict with the battery condition, then drive generator to achieve reduced overall power consumption over a selected time period. In one embodiment, the solar PV system is driven at less than maximum point tracking to provide acceptable battery control. In addition, power and energy management control can vary dependent on relative proportions of energy supplied from different energy sources (e.g., storage, solar PV system, or generator).

p-0051In one embodiment, the power management system and controller can determine the selected power flowing from and to the energy storage system, from the engine and/or from the solar PV based on respective forecasts and estimates for solar PV power and refrigeration consumption. The power set-points for each of the components will be based on energy and power management strategies that will address or prioritize either life-time of the individual equipment or the full system, prioritize on energy efficiency, and/or prioritize on environmental constraints. For example, a load requirement for a transport refrigeration unit can be forecast (e.g., indefinitely) using for example ambient conditions, the cargo itself, and transport refrigeration unit components. The solar PV system capability can be forecast for a relatively short time (e.g., 6 hours, 12 hours, 24 hours), however, with less certainty. Embodiments for energy management control using the power management system and controller can selectively control the amount of energy from each of the storage (e.g., battery), the solar PV system, or the generator using the forecast information. Further, the energy management control can prioritize overall energy consumption by different modes of use such as but not limited to environmental friendly (e.g., prioritize renewable energy sources), overall power consumption (e.g., operate generator at peak efficiency), field conditions (e.g., utilize the solar PV system or battery to reduce noise near a hazardous location), operation convenience (e.g., the generator to load and the solar PV system to charge battery, or the generator to charge battery and the solar PV system to the load).

p-0052Mechanical integration of the solar PV system <b>320</b> can be achieved without significant modification to the trailer. The form profile of the trailer needs to be maintained low to avoid damage from air-flow when the vehicle is in motion. Trailers are designed to be handled by cranes, and may be stacked on rail yards. Often, maintenance personnel need to walk on the roofs as part of hitching and unhitching to cranes. Embodiments of the application incorporate removable and re-installable solar PV systems with no loss of functionality of the container during shipping, handling and/or maintenance. As shown in <figref idrefs="DRAWINGS">FIG. 7</figref>, a frame <b>710</b> in one embodiment can allow for installation of a solar film that will shield the container from solar radiation (a physical barrier), and allow removal for shipping and handling, allow access for maintenance while achieving a low profile. For example, the frame <b>710</b> can be mechanically fastened to container corners using existing features. Alternatively, the solar PV film can be mounted to a backing sheet for attachment or removal from the container without modification to the container itself. In one embodiment, the solar PV system can be additionally selectively mounted on an additional side of the container or trailer.

p-0053<figref idrefs="DRAWINGS">FIG. 8</figref> is a diagram that illustrates another exemplary embodiment of a power management system for a transport refrigeration system according to the application. As shown in <figref idrefs="DRAWINGS">FIG. 8</figref>, power management system and controller <b>840</b> can operate to directly supply power from the solar PV system to the transport refrigeration unit <b>850</b>. The power management system and controller <b>840</b> can adapt power voltage, frequency, and phases (e.g., converters) to levels used by the existing transport refrigeration unit <b>850</b>. Alternatively, energy storage <b>860</b> such as batteries can be optionally included.

p-0054Embodiments of the transport refrigeration systems and methods can increase or maximize the use of solar energy during the times that it is available. In one embodiment, the solar PV system is a high efficiency solar PV system and power management system <b>40</b> constantly monitors and dynamically draws the power from the solar PV system to achieve efficient operations of the solar PV system (e.g., over an operational interval or instantaneously). To maintain the critical functional requirements of the refrigeration system, the power management system <b>40</b> also needs to handle the dynamics of energy supply and demand in real-time.

p-0055In one embodiment, a solar-assisted refrigeration system is provided where the solar availability (e.g., like the energy availability from a falling elevator) is a random variable that needs to be dynamically adapted to by the power management controller.

p-0056Embodiments of an all electric transportation refrigeration system can reduce mechanical hardware such as the stand-by motor, clutches, belts, and pulleys, which can be replaced by cheaper, efficient, and more robust electrical hardware.

p-0057The all-electric system can improve performance by enabling better control algorithms that can seamlessly transition between available energy sources as available. Since solar energy availability can fluctuate, it is important to have a control system that can seamlessly transition between solar power, additional energy sources and the generator to ensure that the refrigeration system power needs are always met.

p-0058Embodiments of the transport refrigeration system have various advantages. The use of thin film solar PV enables increased or maximized coverage over the trailer surfaces; the solar PV is removable and re-installable on the trailer, e.g., no loss of functionality to the trailer; solar utilization is increased or maximized by a peak-power tracking in the controller to follow the power profile of the PV system; overall system controllability is improved over the conventional direct drive system since mechanical actuators are replaced with electrical and electronic systems; fuel-savings are increased or maximized through power management system that seamlessly transitions between available energy sources as required by the load; hardware reduction is achieved by eliminating the stand-by motor and associated mechanical drive components, and reliability is increased by eliminating two-thirds of the serviceable mechanical components found in conventional systems, such as idler pulleys, vibrasorbers, most belts, fan shafts, the compressor shaft seal and clutch.

p-0059Embodiments of the transport refrigeration system (hybrid-electric) enable it to have power from the engine and solar PV cells available for use in the various parts of the refrigeration unit at any given time. In addition, the controller can intelligently manage the storage system and can also be used to start-up the diesel generator when needed. Embodiments of the transport refrigeration system can incorporate such algorithmic features to use the available solar energy, all of which are enabled by the all-electric system.

p-0060It should be understood that although the present application has been described as useful in transport refrigeration systems, those of skill in the art will readily understand and appreciate that the present invention may also be useful, and provide many benefits, in other types of refrigeration systems.

p-0061Exemplary containers and transport refrigeration systems described herein may be towed by a semi-truck for road transport. However, those having ordinary skill in the art will appreciate that exemplary containers according to embodiments of the application is not limited to such trailers and may encompass, by way of example only and not by way of limitation, transport refrigeration systems for intermodal use, trailers adapted for piggy-back use, railroad cars, and container bodies contemplated for land and sea service.

p-0062Components of the transport refrigeration unit (e.g., motors, fans, sensors), as known to one skilled in the art, can communicate with a controller (e.g., transport refrigeration unit) through wire or wireless communications. For example, wireless communications can include one or more radio transceivers such as one or more of 802.11 radio transceiver, Bluetooth radio transceiver, GSM/GPS radio transceiver or WIMAX (802.16) radio transceiver. Information collected by sensor and components can be used as input parameters for a controller to control various components in transport refrigeration systems. In one embodiment, sensors may monitor additional criteria such as humidity, species concentration or the like in the container.

p-0063Embodiments of systems, apparatus, and/or methods can provide power management system configurations and control for integrating solar power into the electrical system of a transport refrigeration system. Embodiments can ensure real-time allocation of power flow into the refrigeration system, both as a function of load or demand, and/or solar energy availability. In one embodiment, thin-film solar fabrics removably attached to the surfaces of the container or trailer body to allow removal and re-installation depending on operational needs in the field.

p-0064While the present invention has been described with reference to a number of specific embodiments, it will be understood that the true spirit and scope of the invention should be determined only with respect to claims that can be supported by the present specification. Further, while in numerous cases herein wherein systems and apparatuses and methods are described as having a certain number of elements it will be understood that such systems, apparatuses and methods can be practiced with fewer than the mentioned certain number of elements. Also, while a number of particular embodiments have been set forth, it will be understood that features and aspects that have been described with reference to each particular embodiment can be used with each remaining particularly set forth embodiment. For example, aspects and/or features of embodiments described with respect to <figref idrefs="DRAWINGS">FIG. 5</figref> can be combined with aspects or features of embodiments described with respect to <figref idrefs="DRAWINGS">FIG. 1</figref> or <figref idrefs="DRAWINGS">FIG. 4</figref>.