Patent Description:
As known, a mobile refrigeration system is typically arranged on a vehicle, train or other vehicles, so as to provide refrigeration for a partial area in the vehicle, e.g., provide refrigeration in a carriage or container. A mobile refrigeration system is usually used for providing refrigeration during transportation of some cargoes, e.g., providing a low-temperature environment during transportation of food which is easily corrupted or products which need to be preserved at low temperature. A transportation refrigeration unit is commonly arranged in a mobile refrigeration system to control environmental states such as temperature in the mobile refrigeration system. A transportation refrigeration unit typically comprises: an engine used for providing driving force or power; a power generator driven by the engine to supply power to power generator loads, which, for example, may be various fans, controllers, batteries and the like; and a refrigeration loop comprising a compressor providing refrigeration.

Since the output power of the engine is limited, power distribution needs to be performed between the engine and the compressor. The existing power management method usually causes power actually distributed to the power generator to be slightly larger, and consequently the power distributed to the compressor is reduced. Therefore, the compressor power determined according to a conventional power management method usually does not realize full utilization of the power of the engine, and the refrigeration efficiency of the refrigeration unit is reduced.

Therefore, there is a continuous demand for an improved power management method and system.

<CIT> discloses an auxiliary power system and method that distributes and controls excess electric power from a trailer box refrigeration system.

<CIT> discloses systems and methods for controlling the amount of power supplied by an engine for a transport refrigeration system to ensure that the engine is operating within a preset window of operation and compliant with emission legislation.

One purpose of the present invention is to provide a power management method, which can increase power distributed to a compressor and improve system efficiency on the premise that power demands of power generator loads are met. Another purpose of the present invention is to provide a power management system.

The present invention provides a power management method used for power distribution in a transportation refrigeration unit according to claim <NUM>.

Optionally, the step of calculating the engine power comprises:.

Optionally, the conversion relationship is generated according to the following method:.

Optionally, the conversion relationship is established by means of linear regression.

Optionally, in a process of managing the power distributed to the compressor, opening of a suction pressure regulating valve at an upstream of the compressor is adjusted to manage the power distributed to the compressor.

According to a second aspect of the invention, a power management system used for power distribution in a transportation refrigeration unit is provided according to claim <NUM>.

Optionally, the engine power calculation module comprises:.

Optionally, the power management system further comprises a conversion relationship generation module comprising:.

Optionally, the conversion relationship establishment module is configured to establish the conversion relationship by means of linear regression.

Optionally, the control module is configured to: receive the available power from the available power calculation module and adjust opening of a suction pressure regulating valve at an upstream of the compressor according to the available power to control the power distributed to the compressor.

Optionally, the first information acquisition module is coupled to a power generator LIN bus and the second information acquisition module is coupled to the power generator LIN bus and an output current sensor.

The power management method and system provided by the present invention have the advantages of simplicity, reliability, stable operation and the like, the power generator real-time input power can be calculated according to the power generator excitation current, thus more power can be provided to the compressor on the premise that the power supply to power generator loads is guaranteed, and the operating efficiency of the transportation refrigeration unit is improved. Besides, the power management method and system provided by the present invention can adaptively change under the situation that the power generator loads change, and thus the system compatibility is improved.

The present invention will be further described below in detail with reference to the drawings in combination with the preferred embodiments. However, one skilled in the art shall understand that these drawings are drawn for the purpose of explaining the preferred embodiments and thus shall not be used as limitations to the scope of the present invention. The scope is defined in the appended claims. Besides, unless otherwise pointed out, the drawings are just used for conceptually illustrating the components or structures of the described objects, possibly contain exaggerated illustration and are not certainly drawn according to scales.

<FIG> illustrates a structural schematic diagram of a transportation refrigeration unit.

<FIG> illustrates a flowchart of a power management method provided by the present invention in one embodiment.

<FIG> illustrates a structural schematic diagram of a power management system provided by the present invention in one embodiment.

The preferred embodiments of the present invention will be described below in detail with reference to the drawings. One skilled in the art shall understand that these descriptions are just descriptive and exemplary and shall not be explained as limitations to the protective scope of the present invention.

Firstly, it needs to be stated that orientation words such as "top", "bottom", "upwards" and "downwards" mentioned herein are defined relative to directions in each drawing, are relatively concepts and can change according to different positions and different practical states. Therefore, these or other orientation words shall not be understood as restrictive words.

Besides, it also needs to be pointed out that any individual technical features described or implied in the embodiments herein or any individual technical features illustrated or implied in the drawings can still be continuously combined between these technical features (or equivalents thereof), so as to obtain other embodiments of the present invention directly mentioned herein.

It shall be noted that the same reference signs in different drawings represent the same or approximately same components.

<FIG> illustrates a structural schematic diagram of a transportation refrigeration unit. Herein, the transportation refrigeration unit <NUM> comprises: an engine <NUM>; a power generator <NUM> and a compressor <NUM>, wherein output power of the engine <NUM> is transmitted to the power generator <NUM> and the compressor <NUM> through a belt or a shaft; and a plurality of electric loads driven by the power generator <NUM>.

Herein, the engine <NUM> is usually a diesel engine and has output power Pe.

The plurality of electric loads may comprise: a battery <NUM>, a condenser fan <NUM>, an evaporator fan <NUM>, a controller <NUM>, a suction pressure regulating valve <NUM> supplied with power and controlled by the controller <NUM>, etc.. The suction pressure regulating valve <NUM> is provided at an upstream of the compressor <NUM> and is used for controlling flow of refrigerant passing through the compressor <NUM>. These electric loads are driven by the power generator <NUM>. Herein, during operation, the condenser fan <NUM>, the evaporator fan <NUM> and the controller <NUM> usually have a demand of relative stable power, while the battery <NUM> has a demand of variable voltage, because it possibly needs larger power when it needs to be charged and does not consume power when it does not need to be charged.

Since the output power Pe of the engine <NUM> is usually limited and stable, power needs to be distributed between the power generator <NUM> and the compressor <NUM>. In the existing power management method, power distributed to the compressor <NUM> is determined according to the following method:.

where Pe is total output of engine, Pcfm is power of condenser fan; Pefm is power of evaporator fan, Pc is power of controller, M is safety margin determined in step (<NUM>) and E is engine efficiency determined in step (<NUM>).

After the available power Pca of the compressor <NUM> is determined, the controller <NUM> can correspondingly give out a control signal to the suction pressure regulating valve <NUM> to adjust the operating state of the compressor <NUM> to adapt to the available power Pca.

However, the existing power management method has various defects. During operation, the calculated available power Pca usually is smaller than the power, which can be actually allocated to the compressor, in the output power of the engine. This is because that, in the existing power management method, in order to meet the demands of non-stable power electric loads such as the battery <NUM>, a comparatively high value is adopted as M, resulting that the estimated values of the power needed by the electric loads of the power generator <NUM> are slightly large and consequently the estimated value of the power allocated to the compressor <NUM> is reduced. This causes that the compressor <NUM> does not operate in an optimum state, and the refrigeration capacity and refrigeration efficiency of the compressor are reduced.

In order to solve the above-mentioned problem, the present invention provides a power management method for a transportation refrigeration unit. <FIG> illustrates a flowchart of a power management method provided by the present invention in one embodiment, wherein the power management method comprises the following steps:.

Further, the step of calculating the engine power Pe comprises:.

In step S22 of one embodiment of the present invention, firstly power at rated temperature can be obtained according to engine revolution speed through a revolution speed-power curve, and then the engine power Pe is calculated according to the temperature of the engine and a temperature correction curve.

Further, the step of calculating the power generator real-time input power Pa comprises:.

Further, the conversion relationship f(x) is generated according to the following method:.

In one embodiment of the present invention, in step S42, the conversion relationship f(x) is established by means of linear regression.

According to one example of data fitting of the present invention, the power generator real output current and the excitation current approximately have a linear relationship therebetween, and the relationship therebetween can be expressed by using a formula y=<NUM>. 0272x+<NUM>, and a certainty coefficient R<NUM> is <NUM>.

Further, in step S50, the available power P<NUM> is calculated by subtracting the power generator real-time input power Pa from the engine power Pe, i.e.: <MAT>.

Further, in step S60, opening of the suction pressure regulating valve <NUM> at an upstream of the compressor <NUM> is adjusted to manage the power distributed to the compressor <NUM>.

<FIG> illustrates a structural schematic diagram of a power management system provided by the present invention in one embodiment. The illustrated power management system is used for power distribution in a transportation refrigeration unit and comprises:.

Further, the engine power calculation module <NUM> comprises:.

In one embodiment of the present invention, the first calculation submodule <NUM> may be configured to firstly obtain power at rated temperature according to engine revolution speed through a revolution speed-power curve, and then calculate the engine power Pe according to the temperature of the engine and a temperature correction curve.

Further, the power generator real-time input power calculation module <NUM> comprises:.

Further, the power management system further comprises a conversion relationship generation module comprising:.

Further, the conversion relationship establishment module <NUM> is configured to establish the conversion relationship f(x) by means of linear regression.

Further, the available power calculation module <NUM> is configured to: receive the engine power Pe from the engine power calculation module <NUM>, receive the power generator real-time input power Pa from the power generator real-time input power calculation module <NUM>, and calculate the available power P<NUM> by subtracting the power generator real-time input power Pa from the engine power Pe, i.e.: <MAT>.

Further, the control module <NUM> is configured to: receive the available power P<NUM> from the available power calculation module <NUM> and adjust opening of a suction pressure regulating valve <NUM> at an upstream of the compressor <NUM> according to the available power P<NUM> to control the power distributed to the compressor <NUM>.

Alternatively, the first information acquisition module <NUM> is coupled to a power generator LIN bus and the second information acquisition module <NUM> is coupled to the power generator LIN bus and an output current sensor.

Alternatively, the power generator excitation current Ie is acquired from a power generator data output. The power generator data output comprises an LIN bus, a CAN bus, a wireless network, a cellular phone network, a bluetooth or the like.

Alternatively, after the conversion relationship f(x) is obtained, the conversion relationship f(x) can be stored in the controller.

The above-mentioned power management method and system can be typically used in the transportation refrigeration unit illustrated in <FIG>. During operation, the power generator real output current Iro simultaneously reflects the power demands of all power generator loads, and can also reflect the power demand of the battery under the situation that the power demands of parts such as the fans and the controller are met.

The power management method provided by the present invention can more accurately identify real power consumed by the power generator loads in the transportation refrigeration unit, thus the value of power allocated to the power generator to be more accurate and the power is prevented from being wasted. Besides, the power management method provided by the present invention can allocate more power to the compressor in the transportation refrigeration unit, thus the refrigeration capacity is improved, which helps the product to get an environmental certification.

Claim 1:
A power management method used for power distribution in a transportation refrigeration unit (<NUM>), the transportation refrigeration unit comprising: an engine (<NUM>); a power generator (<NUM>) and a compressor (<NUM>), wherein output power of the engine is transmitted to the power generator and the compressor through a belt or a shaft, and wherein the power management method comprises the following steps:
calculating (S22) engine power according to engine operating parameters (S21), characterized by:
calculating (S33) power generator real-time input power according to power generator excitation current (S31b);
calculating (S50) available power based on the power generator real-time input power and the engine power wherein, in the process of calculating (S50) the available power, the available power is calculated by subtracting the power generator real-time input power from the engine power; and
managing (S60) power distributed to the compressor based on the available power,
wherein the step of calculating the power generator real-time input power comprises:
acquiring power generator efficiency (S31a), power generator excitation current (S31b) and power generator voltage (S31c);
acquiring (S32a) a conversion relationship and substituting (S32b) the power generator excitation current into the conversion relationship to obtain (S32c) power generator real output current; and
multiplying (S33) the power generator real output current by the power generator voltage and dividing by the power generator efficiency to calculate the power generator real-time input power.