Patent Grant
10590942
The present disclosure relates to systems and methods for controlling a compressor for use in a fuel cell circuit of a vehicle and, more particularly, to systems and methods for creating a real-time model of the compressor and controlling the compressor using the real-time model.
Fuel cell vehicles are becoming more and more popular. Fuel cells may receive air and hydrogen and may facilitate a reaction between the air and hydrogen to generate electricity. The electricity may be stored in a battery and/or received by a motor generator of the vehicle which converts the electrical energy into mechanical power for propelling the vehicle.
Fuel cell vehicles typically include a fuel cell circuit that provides the air to the fuel cells. The fuel cell circuit may include a compressor that compresses the air and directs the pressurized air to the fuel cells. Due to the complexity of the fuel cell circuit, an electronic control unit (ECU) of the vehicle may control the fuel cell circuit using a real-time model.
Compressors may be relatively difficult to model due to the interaction of multiple coupled states of the compressor. In particular, the multiple coupled states may include a compressor speed, a compressor flow rate, and a compressor pressure ratio corresponding to a ratio of a pressure at an outlet of the compressor to a pressure at an inlet of the compressor. Because the states are coupled, a change in one of the states results in a change in the remaining states. Because of this coupling, real-time modeling of a compressor is relatively difficult.
Accordingly, there is a need in the art for systems and methods for creating a real-time model of a compressor, and controlling the compressor using the real-time model.
Described herein is a system for real-time controller modeling. The system includes a compressor having an inlet and an outlet and designed to operate at a compressor speed, a compressor flow rate corresponding to a flow of fluid through the compressor, and a compressor pressure ratio corresponding to a ratio of an inlet pressure at the inlet to an outlet pressure at the outlet. The system also includes a memory designed to store an operating condition matrix that plots multiple compressor pressure ratios to each of a plurality of compressor speeds, and an operating state matrix that plots multiple compressor flow rates to each of the plurality of compressor speeds, the operating condition matrix being related to the operating state matrix such that a first compressor pressure ratio at a first location of the operating condition matrix corresponds to a first compressor flow rate at a corresponding location of the operating state matrix. The system also includes a compressor controller coupled to the compressor and the memory. The compressor controller is designed to determine a current or target compressor speed and a current or target compressor pressure ratio. The compressor controller is also designed to identify a current or target location in the operating condition matrix based on the current or target compressor speed and the current or target compressor pressure ratio. The compressor controller is also designed to determine a current or target compressor flow rate by interpolating values in the operating state matrix based on the current or target location. The compressor controller is also designed to control the compressor based on the current or target compressor flow rate.
Also described is a method for real-time modeling of a compressor. The method includes storing, in a memory, an operating condition matrix that plots multiple compressor pressure ratios to each of a plurality of compressor speeds. The method also includes storing, in the memory, an operating state matrix that plots multiple compressor flow rates to each of the plurality of compressor speeds, the operating condition matrix being related to the operating state matrix such that a first compressor pressure ratio at a first location of the operating condition matrix corresponds to a first compressor flow rate at a corresponding location of the operating state matrix. The method also includes determining, by a compressor controller, a current or target compressor speed and a current or target compressor pressure ratio. The method also includes identifying, by the compressor controller, a current or target location in the operating condition matrix based on the current or target compressor speed and the current or target compressor pressure ratio. The method also includes determining, by the compressor controller, a current or target compressor flow rate by interpolating values in the operating state matrix based on the current or target location. The method also includes controlling, by the compressor controller, the compressor based on the current or target compressor flow rate.
Also described is a method for real-time modeling of a compressor. The method includes obtaining, by a model controller, test data including combinations of compressor speeds, compressor pressure ratios, and compressor flow rates. The method also includes generating, by the model controller, an operating condition matrix that plots multiple compressor pressure ratios to each of a plurality of compressor speeds based on the test data. The method also includes generating, by the model controller, an operating state matrix that plots multiple compressor flow rates to each of the plurality of compressor speeds based on the test data. The method also includes providing the operating condition matrix and the operating state matrix to a compressor controller as a model of the compressor such that the compressor controller can control the compressor based on the model.
Other systems, methods, features, and advantages of the present invention will be or will become apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. Component parts shown in the drawings are not necessarily to scale, and may be exaggerated to better illustrate the important features of the present invention. In the drawings, like reference numerals designate like parts throughout the different views, wherein:
The present disclosure describes systems and methods for creating a real-time model of a compressor, and controlling the compressor using the real-time model. The systems provide several benefits and advantages, for example, such as taking advantage of the fact that the multiple states of the compressor are homotopic. By recognizing the fact that the compressor states are homotopic, the systems advantageously create a real-time model that includes a relatively small amount of data, which results in significant memory savings. The systems can advantageously interpolate between the data points of the model due to the fact that the states are homotopic, which allows the model to be performed using relatively little processing power. The homotopic relationship between the states results in interpolation between states being linear, which allows the system to control the compressor with relatively high accuracy.
An exemplary system includes a memory, a compressor controller, and a compressor. The memory may store an operating condition matrix that includes multiple pressure ratios for each of a plurality of compressor speeds. The memory may also store an operating state matrix that includes multiple compressor flow rates for each of the plurality of compressor speeds. The operating condition matrix corresponds to the operating state matrix such that a location in the operating state matrix corresponds to the same location in the operating condition matrix. The compressor controller may receive a target compressor pressure ratio and a target compressor speed and may wish to determine a target compressor flow rate. The compressor controller may then find a location in the operating condition matrix that corresponds to the target pressure ratio and the target compressor speed. The compressor controller may then identify the corresponding location in the operating state matrix. The compressor controller may then interpolate between the values in the operating state matrix that are adjacent to the corresponding location, the interpolation resulting in the target compressor flow rate.
Turning to
The ECU 102 may be coupled to each of the components of the vehicle 100 and may include one or more processors or controllers, which may be specifically designed for automotive systems. The functions of the ECU 102 may be implemented in a single ECU or in multiple ECUs. The ECU 102 may receive data from components of the vehicle 100, may make determinations based on the received data, and may control the operation of components based on the determinations.
In some embodiments, the vehicle 100 may be fully autonomous or semi-autonomous. In that regard, the ECU 102 may control various aspects of the vehicle 100 (such as steering, braking, accelerating, or the like) to maneuver the vehicle 100 from a starting location to a destination.
The memory 104 may include any non-transitory memory known in the art. In that regard, the memory 104 may store machine-readable instructions usable by the ECU 102 and may store other data as requested by the ECU 102 or programmed by a vehicle manufacturer or operator. The memory 104 may store a model of components of the fuel cell circuit 118. The model may include equations or matrices usable to estimate various parameters of the components of the fuel cell circuit 118.
The engine 112 may convert a fuel into mechanical power. In that regard, the engine 112 may be a gasoline engine, a diesel engine, or the like.
The battery 116 may store electrical energy. In some embodiments, the battery 116 may include any one or more energy storage device including a battery, a fly-wheel, a super-capacitor, a thermal storage device, or the like.
The fuel cell circuit 118 may include a plurality of fuel cells that facilitate a chemical reaction to generate electrical energy. For example, the fuel cells may receive hydrogen and oxygen, facilitate a reaction between the hydrogen and oxygen, and output electricity in response to the reaction. In that regard, the electrical energy generated by the fuel cell circuit 118 may be stored in the battery 116. In some embodiments, the vehicle 100 may include multiple fuel cell circuits including the fuel cell circuit 118.
The motor-generator 114 may convert the electrical energy stored in the battery (or electrical energy received directly from the fuel cell circuit 118) into mechanical power usable to propel the vehicle 100. The motor-generator 114 may further convert mechanical power received from the engine 112 or wheels of the vehicle 100 into electricity, which may be stored in the battery 116 as energy and/or used by other components of the vehicle 100. In some embodiments, the motor-generator 114 may also or instead include a turbine or other device capable of generating thrust.
Turning now to
The air intake 200 may receive air from an ambient environment, such as outside of the vehicle 100 of
The compressor 204 may be a turbo compressor or other compressor capable of pressurizing air. In that regard, the compressor 204 may draw air from the cleaner 202 and may output pressurized air.
The intercooler 206 may receive the air from the compressor 204 and may also receive a fluid, such as a coolant. The intercooler 206 may transfer heat from the air to the coolant, or may transfer heat from the coolant to the air. In that regard, the intercooler 206 may adjust a temperature of the air flowing through the fuel cell circuit 118.
The fuel cell stack 208 may include a plurality of fuel cells. The fuel cells may receive hydrogen along with the air from the intercooler 206. The fuel cells may facilitate a chemical reaction between the oxygen in the air and the hydrogen, which may generate electricity.
The air from the intercooler 206 may be split such that some of the air flows through the fuel cell stack 208 and some of the air flows through the bypass branch 210. In that regard, the air flowing through the bypass branch 210 fails to flow through the fuel cell stack 208. The bypass valve 212 may have an adjustable valve position controllable to adjust an amount of airflow through the bypass branch 210.
The restriction valve 214 may likewise have an adjustable valve position controllable to adjust a pressure of the air within the fuel cell stack 208.
Referring to
The compressor flow rate, the compressor speed, and the compressor pressure ratio may be referred to as coupled states because a change in one of the states results in a change to the remaining states. For example, a change in pressure ratio across the compressor 204 may result in a change in compressor speed and a change in compressor flow rate.
Turning now to
The model creation system 302 may include a model controller 306, a memory 308, and a compressor or model of a compressor 310. The model controller 306 may receive test data from the compressor or the model of the compressor 310. The model controller 306 may then create a real-time model of the compressor which may be used to control the compressor in real-time. The real-time model of the compressor may then be stored in the memory 308. The real-time model may differ from the model of the compressor 310 because the model of the compressor 310 may be incapable of running in real-time.
The compressor control system 304 includes a compressor controller 312, a memory 314, and a physical compressor 316. In various embodiments, the compressor controller 312 may be the ECU 102 of
For example, the compressor controller 312 may determine or receive a desired compressor speed and a desired compressor pressure ratio. The compressor controller 312 may then use the real-time model to identify a desired compressor flow rate, and may then control the compressor 316 to have the desired compressor flow rate.
Turning now to
The compressor flow rate, compressor pressure ratio, and compressor speed may be homotopic operating states of the compressor. Referring to
Returning reference to
Referring to
The operating state matrix 650 may be similarly oriented and may plot compressor speeds 652 against compressor flow rates 654. In particular, the operating state matrix 650 includes a plurality of rows 656 each corresponding to one of a plurality of compressor speeds, and a plurality of columns 658 each corresponding to equally spaced locations between the surge line 504 and the stall line 506. For example, a first row 650 may correspond to speed 1, which corresponds to the speed line 508 (which corresponds to the same compressor speed as the first row 610 of the operating condition matrix 600). A first column 662 may correspond to the first location 514, and a second column 664 may correspond to a second location 516. In that regard, a compressor flow rate 666 may correspond to the compressor flow rate at the first location 514, and a compressor flow rate 668 may correspond to the compressor flow rate at the second location 516.
A quantity of columns of the operating condition matrix 600 may be equal to a quantity of columns in the operating state matrix 650. Furthermore, the cells of the operating condition matrix 600 may correspond to the cells of the operating state matrix 650. In that regard, when the compressor experiences the first speed corresponding to the first row 610 and the second pressure ratio 618, examination of the operating condition matrix 600 and the operating state matrix 650 indicates that the compressor will likewise experience the second airflow rate 668. This is because each cell of the operating state matrix 650 corresponds to an equally positioned cell in the operating condition matrix 600.
Returning reference to
In block 406, the compressor controller may create a pressure ratio array by interpolating between pressure ratios of the operating condition matrix. For example, the compressor controller may create a pressure ratio array by interpolating between two lines of the operating condition matrix based on the current or target compressor speed.
For example and referring to
Returning reference to
For example and referring to
Returning reference to
Returning reference to
Returning reference to
For example and returning reference to
The above example provides one manner of determining a current or target compressor flow rate by interpolating values in the operating condition matrix and in the operating state matrix. In some embodiments, the compressor controller may interpolate values in the operating condition matrix and the operating state matrix directly without creating a pressure ratio array and a flow array. For example, the location 724 within the pressure ratio array 720 also corresponds to a location 710 in the operating condition matrix. Based on this information, the compressor controller may determine the current or target compressor flow rate by interpolating between values at a corresponding location 760 of the operating state matrix.
Returning reference to
Turning now to
In block 802, a model controller may receive test data corresponding to operation of a compressor. For example, the test data may be obtained by performing testing using a physical compressor or using a non-real-time model of a physical compressor. Referring briefly to
Returning reference to
Referring now to
As another example, the model controller may create a set of lines 914 based on the points of the test data 902, and then may calculate the compressor ratio values along the set of lines. In that regard, the model controller may create the operating condition matrix using a line fitting technique.
Returning reference to
Returning reference to
Where used throughout the specification and the claims, “at least one of A or B” includes “A” only, “B” only, or “A and B.” Exemplary embodiments of the methods/systems have been disclosed in an illustrative style. Accordingly, the terminology employed throughout should be read in a non-limiting manner. Although minor modifications to the teachings herein will occur to those well versed in the art, it shall be understood that what is intended to be circumscribed within the scope of the patent warranted hereon are all such embodiments that reasonably fall within the scope of the advancement to the art hereby contributed, and that that scope shall not be restricted, except in light of the appended claims and their equivalents.
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