Battery charging method, battery charging system, hybrid system and train
By predicting the state of charge of the power battery and adjusting the charging strategy according to the driving environment, the energy management problem of hybrid trains under different gradients is solved, enabling long-term operation of the fuel cell system and improving the economic efficiency of train operation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CRRC QINGDAO SIFANG CO LTD
- Filing Date
- 2024-01-31
- Publication Date
- 2026-06-23
AI Technical Summary
Existing hybrid trains experience rapid increases in the state of charge of the power battery on long downhill slopes, leading to energy loss, while on long uphill slopes, the state of charge decreases rapidly, affecting traction and acceleration performance and potentially damaging the durability and lifespan of the fuel cell.
By predicting the state of charge of the power battery and adjusting the charging strategy according to the driving environment, the fuel cell system is used for dynamic matching interval charging, optimizing the charging power to maintain the operating time of the fuel cell system, reducing the number of start-stop cycles, and improving durability and train operation economy.
It effectively optimizes battery charging for trains under different operating conditions, ensures long-term operation of the fuel cell system, reduces the number of start-stop cycles, and improves the durability of the fuel cell system and the economic efficiency of train operation.
Smart Images
Figure CN117755108B_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of electrified rail transit, and more specifically to a battery charging method, a battery charging system, a hybrid power system, and a train. Background Technology
[0002] With the rapid growth of traditional vehicles, environmental pollution caused by fossil fuels has become increasingly serious, making hybrid vehicles or trains a research hotspot. Among them, hydrogen fuel cells, with their advantages of energy saving, cleanliness, and high efficiency, have become the development direction of the next generation of automobiles or trains.
[0003] Current energy management strategies applied to hybrid trains have the following problems in practical use: First, when the train travels on a long downhill slope, the state of charge (SOC) of the power battery rises sharply and quickly reaches its upper limit, making it impossible to recover braking energy and resulting in energy loss. Second, when the train travels on a long uphill slope, the SOC of the power battery drops sharply and quickly reaches its lower limit, preventing the power battery from replenishing peak power during traction and affecting the train's traction and acceleration performance. These problems may affect the durability and lifespan of the fuel cells in hybrid trains. Summary of the Invention
[0004] In view of the above problems, this disclosure provides a battery charging method, a battery charging system, a hybrid power system, and a train.
[0005] According to a first aspect of this disclosure, a battery charging method is provided, comprising:
[0006] Based on the state of charge of the power battery at time i and the traction and braking parameters, predict the state of charge parameters of the power battery at time i+1.
[0007] When the above-mentioned (i+1)th state of charge parameter satisfies the preset state parameter range and the driving environment is the target environment, the target state of charge is determined according to the above-mentioned power battery's set of charge parameters, wherein the above-mentioned set of charge parameters includes multiple battery parameters characterizing the physical performance of the above-mentioned power battery.
[0008] The target matching interval of the actual state of charge of the power battery at time i+1 is determined in the state matching table. The state matching table includes multiple initial matching intervals and the charging power corresponding to each initial matching interval. The charging power is determined based on the actual state of charge and the target state of charge.
[0009] The power battery is charged by the fuel cell system based on the target charging power corresponding to the target matching range.
[0010] According to embodiments of this disclosure, the charging power is determined by performing proportional-integral calculations on the actual state of charge and the target state of charge using a linear controller.
[0011] According to embodiments of this disclosure, the above-mentioned i+1th state of charge parameter includes an i+1th predicted upper limit value and an i+1th predicted lower limit value;
[0012] Specifically, based on the i-th state of charge and traction braking parameters at time i, the (i+1)-th state of charge parameters at time i+1 are predicted, including:
[0013] A first intermediate value is generated based on the battery charge data during the traction braking process, the first electromotive force corresponding to the i-th state of charge, and the rated capacity of the power battery. The traction braking operating condition parameters include the battery charge data, the first electromotive force, and the rated capacity.
[0014] Based on the first intermediate value and the i-th state of charge, the (i+1)-th prediction upper limit value and the (i+1)-th prediction lower limit value are generated respectively.
[0015] According to embodiments of this disclosure, the battery charging method further includes:
[0016] If the above-mentioned (i+1)th state of charge parameter satisfies the preset state parameter range but the driving environment is not the target environment, the above-mentioned state of charge balance value of the power battery is used to determine the above-mentioned target state of charge.
[0017] According to embodiments of this disclosure, when the above-mentioned (i+1)th state of charge parameter satisfies a preset state parameter range and the driving environment is the target environment, the target state of charge is determined based on the above-mentioned power battery charge parameter set, including:
[0018] When the above-mentioned (i+1)th state of charge parameter is greater than the upper limit of the parameter interval or less than the lower limit of the parameter interval, and the above-mentioned driving environment is the above-mentioned target environment, the target state of charge is determined according to the above-mentioned power battery charge parameter set, wherein the above-mentioned preset state parameter interval includes the above-mentioned parameter interval upper limit and the above-mentioned parameter interval lower limit.
[0019] According to embodiments of this disclosure, the target environment includes a target uphill environment and a target downhill environment that meet preset conditions, wherein the preset conditions include a length greater than a preset length and / or a slope greater than a preset slope.
[0020] According to embodiments of this disclosure, determining the target state of charge based on the aforementioned set of charge parameters of the power battery includes:
[0021] A second intermediate value is generated based on the state of charge balance value, the second electromotive force corresponding to the above state of charge balance value, and the rated capacity of the above power battery.
[0022] Based on the second intermediate value and the battery power data during the traction process, a third intermediate value corresponding to the target uphill environment or a fourth intermediate value corresponding to the target downhill environment is generated.
[0023] For any one of the aforementioned third intermediate value and the aforementioned fourth intermediate value, the aforementioned target state of charge is generated based on the aforementioned intermediate value and the reference value, wherein the aforementioned reference value is generated based on the aforementioned rated capacity and the third electromotive force corresponding to the aforementioned i-th state of charge.
[0024] According to embodiments of this disclosure, generating the target state of charge based on the aforementioned intermediate and reference values includes:
[0025] Given that the aforementioned intermediate value is the aforementioned third intermediate value, a first target state of charge under the target uphill environment is generated based on the aforementioned third intermediate value and the aforementioned reference value; or
[0026] When the above intermediate value is the above fourth intermediate value, a second target state of charge under the target downhill environment is generated based on the above fourth intermediate value and the above reference value, wherein the above target state of charge includes the above first target state of charge or the above second target state of charge.
[0027] According to embodiments of this disclosure, determining the target matching interval of the actual state of charge at time i+1 in the state matching table includes:
[0028] The initial charged state interval in the state matching table is divided into multiple consecutive initial matching intervals based on multiple state endpoint values.
[0029] The charging power for each of the above initial matching intervals is determined based on the actual state of charge and the target state of charge.
[0030] The target matching interval to which the actual state of charge at time i+1 belongs is determined from multiple initial matching intervals.
[0031] According to embodiments of this disclosure, when the above-mentioned state endpoint values are SOC1, SOC2, and SOC3 from smallest to largest, the initial matching intervals are [0, SOC1), [SOC1, SOC2), [SOC2, SOC3), and [SOC3, 1], respectively.
[0032] The process of determining the charging power for each of the initial matching intervals based on the actual state of charge and the target state of charge includes:
[0033] For the initial matching interval [0, SOC1), the proportional-integral result is determined as the charging power corresponding to the initial matching interval [0, SOC1), wherein the proportional-integral result is obtained by performing proportional-integral operation on the actual state of charge and the target state of charge.
[0034] For the initial matching interval [SOC1, SOC2) or [SOC2, SOC3), the charging power corresponding to the initial matching interval [SOC1, SOC2) is determined based on the integral difference result and the idle power of the fuel cell. The integral difference result is generated based on the proportional integral result and the power step decrease difference.
[0035] For the initial matching interval [SOC3, 1], the idle power of the fuel cell is determined to be the charging power corresponding to the initial matching interval [SOC3, 1].
[0036] According to a second aspect of this disclosure, a battery charging system is provided, comprising:
[0037] Power battery;
[0038] A fuel cell system for charging the aforementioned power battery under the control of an energy management controller;
[0039] The aforementioned energy management controller is configured as follows:
[0040] Based on the state of charge and traction braking parameters of the power battery at time i, predict the state of charge parameters of the power battery at time i+1.
[0041] When the above-mentioned (i+1)th state of charge parameter satisfies the preset state parameter range and the driving environment is the target environment, the target state of charge is determined according to the above-mentioned power battery's set of charge parameters, wherein the above-mentioned set of charge parameters includes multiple battery parameters characterizing the physical performance of the above-mentioned power battery.
[0042] The target matching interval of the actual state of charge of the power battery at time i+1 is determined in the state matching table. The state matching table includes multiple initial matching intervals and the charging power corresponding to each initial matching interval. The charging power is determined based on the actual state of charge and the target state of charge.
[0043] The power battery is charged by the fuel cell system based on the target charging power corresponding to the target matching range.
[0044] According to a third aspect of this disclosure, a hybrid power system is provided, comprising:
[0045] The fuel cell system, converter, inverter, and traction motor are connected in sequence.
[0046] The power battery is connected in the line between the converter and the inverter.
[0047] An energy management controller is connected to the aforementioned fuel cell system, the aforementioned converter, the aforementioned inverter, the aforementioned power battery, and the aforementioned traction motor, respectively.
[0048] The energy management controller charges the power battery according to the battery charging method described above.
[0049] According to a fourth aspect of this disclosure, a train is provided, wherein the train is powered by a hybrid power system as described above.
[0050] According to embodiments of this disclosure, by predicting the state of charge (SOC) parameters for the next moment based on the current SOC parameters and traction braking parameters, it is determined whether the SOC parameters for the next moment meet the preset parameter range and whether the driving environment is the target environment. The target SOC is then calculated based on the battery's charge parameter set. Based on the target SOC and the actual SOC, the charging power corresponding to each initial matching interval in the state matching table is calculated. The target charging power of the battery that matches its target matching interval is then selected to charge the battery. This optimizes the battery charging power in each initial matching interval under static train conditions, ensuring a longer operating time for the fuel cell system, reducing the number of start-stop cycles of the fuel cell system, and thus improving the durability of the fuel cell system and the economy of train operation. Attached Figure Description
[0051] The foregoing contents, as well as other objects, features, and advantages of this disclosure, will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:
[0052] Figure 1 A flowchart illustrating a battery charging method according to an embodiment of the present disclosure is shown schematically.
[0053] Figure 2 This schematic diagram illustrates a battery charging scenario for a train under static conditions according to an embodiment of the present disclosure.
[0054] Figure 3 A schematic diagram of the structure of a hybrid power system according to an embodiment of the present disclosure is shown; and
[0055] Figure 4 A schematic diagram illustrating the energy distribution of a hybrid power system according to an embodiment of the present disclosure is shown. Detailed Implementation
[0056] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.
[0057] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.
[0058] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.
[0059] When using expressions such as "at least one of A, B, and C", they should generally be interpreted in accordance with the meaning that is commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B, and C, etc.).
[0060] Figure 1 A flowchart illustrating a battery charging method according to an embodiment of the present disclosure is shown schematically.
[0061] like Figure 1 As shown, this disclosure provides a battery charging method, which includes operations S110 to S140.
[0062] In operation S110, based on the state-of-charge parameters of the power battery at time i and the traction braking condition parameters at time i, the state-of-charge parameters of the power battery at time i+1 are predicted.
[0063] In operation S120, when the (i+1)th state of charge parameter satisfies the preset state parameter range and the driving environment is the target environment, the target state of charge is determined according to the set of charge parameters of the power battery. The set of charge parameters includes multiple battery parameters characterizing the physical performance of the power battery.
[0064] In operation S130, the actual state of charge of the power battery at time i+1 is determined to be within the target matching interval of the state matching table. The state matching table includes multiple initial matching intervals and the charging power corresponding to each initial matching interval. The charging power is determined based on the actual state of charge and the target state of charge.
[0065] In operation S140, the fuel cell system charges the power battery based on the target charging power corresponding to the target matching range.
[0066] According to embodiments of this disclosure, the state of charge (SOC) refers to the remaining charge in the power battery. Here, i is a positive integer greater than 0.
[0067] According to embodiments of this disclosure, the type of fuel cell used in fuel cell systems for rail transit is primarily a proton exchange membrane fuel cell. In most applications, the fuel cell is coupled to a battery (e.g., a power battery) or other energy storage device. In this configuration, the fuel cell can serve as the primary power source, providing ample power or charging the battery. In embodiments of this disclosure, the fuel cell is a hydrogen fuel cell. Hydrogen fuel cells, as a novel green energy technology, directly convert energy into electricity through an electrochemical reaction. The conversion process is not limited by the Carnot cycle and offers advantages such as high energy conversion efficiency, zero pollution, low noise, modular structure, and high specific power. They can be used for both centralized and distributed power supply.
[0068] According to embodiments of this disclosure, traction and braking parameters characterize battery parameters when the power battery is consumed during the operation of a train using this battery charging method, such as rated capacity, power consumption data, and electromotive force. The operating environment can refer to the geographical environment in which the train travels, such as long straight-line travel, uphill, downhill, and the corresponding gradient and length.
[0069] According to embodiments of this disclosure, the preset state parameter range includes the upper limit of the state of charge (SOC) parameter range of the power battery. up and the lower limit of the parameter range SOC down Its specific value can be set according to specific needs; for example, it can be set to SOC. up =95%, SOC down =10%.
[0070] According to an embodiment of this disclosure, during the real-time operation of the train, based on the i-th state of charge parameter of the power battery at the current moment, after the next stage of traction and braking conditions, it is predicted whether the (i+1)-th state of charge parameter of the power battery exceeds the preset state parameter range.
[0071] According to embodiments of this disclosure, if the (i+1)th state of charge parameter exceeds a preset state parameter range (i.e., the preset state parameter range is satisfied), and the train is in a target environment, such as an uphill environment with a long length and steep gradient, the target state of charge (SOC) can be determined based on the set of charge parameters of the power battery. idea .
[0072] According to embodiments of this disclosure, the state of charge is divided into intervals in the state matching table to obtain multiple initial matching intervals. Each initial matching interval corresponds to a charging power. Based on the actual state of charge at time i+1, this disclosure determines a target matching interval from the multiple initial matching intervals. After determining the target matching interval, the target charging power is determined based on the actual state of charge and the target state of charge. Thus, the fuel cell system charges the power battery based on the target charging power corresponding to the target matching interval.
[0073] According to embodiments of this disclosure, by predicting the state of charge (SOC) parameters for the next moment based on the current SOC parameters and traction braking parameters, it is determined whether the SOC parameters for the next moment meet the preset parameter range and whether the driving environment is the target environment. The target SOC is then calculated based on the battery's charge parameter set. Based on the target SOC and the actual SOC, the charging power corresponding to each initial matching interval in the state matching table is calculated. The target charging power of the battery that matches its target matching interval is then selected to charge the battery. This optimizes the battery charging power in each initial matching interval under static train conditions, ensuring a longer operating time for the fuel cell system, reducing the number of start-stop cycles of the fuel cell system, and thus improving the durability of the fuel cell system and the economy of train operation.
[0074] According to embodiments of this disclosure, the charging power is determined by performing proportional-integral calculations on the actual state of charge and the target state of charge using a linear controller.
[0075] According to embodiments of this disclosure, a linear controller is a device that controls a controlled object by forming a control deviation based on a given value and an actual output value, and then combining the proportional and integral of the deviation linearly to form a control quantity. For example, it may be a PI controller.
[0076] According to embodiments of this disclosure, the (i+1)th state of charge parameter includes an (i+1)th predicted upper limit value and an (i+1)th predicted lower limit value.
[0077] Specifically, based on the state-of-charge parameters at time i and the traction braking parameters at time i, the (i+1)th state-of-charge parameters at time i+1 are predicted, including:
[0078] A first intermediate value is generated based on the battery charge data during the traction braking process, the first electromotive force corresponding to the i-th state of charge, and the rated capacity of the power battery. The traction braking operating condition parameters include the battery charge data, the first electromotive force, and the rated capacity.
[0079] Based on the first intermediate value and the i-th state of charge parameter, the (i+1)-th prediction upper limit value and the (i+1)-th prediction lower limit value are generated respectively.
[0080] According to embodiments of this disclosure, the upper limit of the prediction during the traction process As shown in formula (1), the lower limit of the prediction during the braking process As shown in formula (2):
[0081]
[0082]
[0083] in, These represent the predicted upper and lower limits of the State of Charge (SOC) of the power battery after traction and braking, respectively; SOC real Indicates the current SOC of the power battery; E drv This represents the power consumption data of the power battery during traction; V represents the state of charge (SOC) of the power battery. real The corresponding first electromotive force; Q represents the rated capacity of the power battery, E brk This indicates the amount of energy recovered by the power battery during braking. The battery capacity data includes both energy consumption and recovered energy. and Both represent the first intermediate value.
[0084] According to embodiments of this disclosure, the battery charging method further includes: when the (i+1)th state of charge parameter satisfies a preset state parameter range but the driving environment is not the target environment, determining the state of charge balance value of the power battery as the target state of charge.
[0085] According to embodiments of this disclosure, the state of charge balance (SOC) value... bal It is obtained by statistical processing of multiple state-of-charge parameters of the power battery within at least one statistical period.
[0086] According to embodiments of this disclosure, if the (i+1)th state of charge parameter in the next stage meets the preset state parameter range, but the train's operating environment is not the target environment such as a long, steep uphill or downhill section, then it is only necessary to adjust the state of charge balance value (SOC) of the power battery. bal The target state of charge is determined, and the charging power of the state matching table is calculated based on this target state of charge.
[0087] According to embodiments of this disclosure, if the (i+1)th time represents the current time, and if the (i+1)th state of charge parameter at this time satisfies the preset state parameter range and the driving environment is the target environment, then the charging power in the state matching table is calculated using the target state of charge determined based on the set of charge parameters, and the power battery is charged using the charging power in this state matching table at the current time. If the (i+2)th time of the next moment satisfies the preset state parameter range but the driving environment is not the target environment, that is, the train's driving environment is removed from the target environment, then the state of charge balance value (SOC) can be directly calculated. bal The target state of charge is determined, and the charging power of the state matching table is calculated based on the target state of charge to charge the power battery.
[0088] According to an embodiment of this disclosure, when the (i+1)th state of charge parameter satisfies a preset state parameter range and the driving environment is the target environment, the target state of charge is determined based on the set of charge parameters of the power battery. This includes: when the (i+1)th state of charge parameter is greater than the upper limit of the parameter range or less than the lower limit of the parameter range, and the driving environment is the target environment, the target state of charge is determined based on the set of charge parameters of the power battery. The preset state parameter range includes the upper limit of the parameter range and the lower limit of the parameter range.
[0089] According to embodiments of this disclosure, if during traction, the (i+1)th state of charge parameter SOC greater than the upper limit of the parameter range up At this time, the train's operating environment is a target environment such as a long uphill slope with a large gradient. The target state of charge can be determined based on the charge parameter set of the power battery.
[0090] According to embodiments of this disclosure, if during braking, the (i+1)th state of charge parameter SOC greater than the upper limit of the parameter range up At this time, the train's operating environment is a target environment such as a long uphill slope with a large gradient. The target state of charge can be determined based on the charge parameter set of the power battery.
[0091] According to embodiments of this disclosure, the target environment includes a target uphill environment and a target downhill environment that meet preset conditions, the preset conditions including a length greater than a preset length and / or a slope greater than a preset slope.
[0092] According to the embodiments of this disclosure, the preset length and preset slope can be specifically set according to actual needs. For example, the preset length can be set to 1km, 10km, etc., and the preset slope can be set to ±10‰, that is, the train moves forward (horizontally) for 1000 meters, rises (+) or falls (-) for 10 meters.
[0093] According to embodiments of this disclosure, determining a target state of charge based on a set of charge parameters of a power battery includes:
[0094] Based on the state of charge balance value SOC bal The second electromotive force V corresponding to the state of charge equilibrium value bal The rated capacity Q of the power battery is used to generate a second intermediate value;
[0095] Based on the second intermediate value and the battery power data during the traction process, generate a third intermediate value corresponding to the target uphill environment or a fourth intermediate value corresponding to the target downhill environment.
[0096] For any intermediate value between the third and fourth intermediate values, a target state of charge is generated based on the intermediate value and a reference value, wherein the reference value is based on the rated capacity Q and the third electromotive force V corresponding to the i-th state of charge. real Generated.
[0097] According to embodiments of this disclosure, the target state of charge (SOC) is calculated based on the energy recovery charge during braking and the power battery charge consumption data during traction. idea When the train is in an uphill environment, the target state of charge is adjusted to a high level to meet the traction power demand; when the train is in a downhill environment, the target state of charge is adjusted to a low level to meet the energy recovery demand.
[0098] According to embodiments of this disclosure, when the train is in a target uphill environment, the target state of charge (SOC) is... idea As shown in formula (3):
[0099]
[0100] Among them, SOC bal V represents the state-of-charge balance value of the power battery; bal Indicates the state of charge (SOC) of the power battery bal The corresponding second electromotive force; V real This represents the third electromotive force corresponding to the current state of charge (SOC) of the power battery, where SOC... bal *Q*V bal Indicates the second intermediate value, SOC bal *Q*V bal +E drv Representing the third intermediate value, Q*V real Indicates a reference value.
[0101] According to embodiments of this disclosure, when the train is in a target downhill environment, the target state of charge (SOC) is... idea As shown in formula (4):
[0102]
[0103] Among them, SOC bal *Q*V bal -E brk This represents the fourth intermediate value.
[0104] According to embodiments of this disclosure, generating a target state of charge based on intermediate and reference values includes:
[0105] Given that the intermediate value is the third intermediate value, the first target state of charge under the target uphill environment is generated based on the third intermediate value and the reference value; or
[0106] When the intermediate value is the fourth intermediate value, a second target state of charge under the target downhill environment is generated based on the fourth intermediate value and the reference value. The target state of charge includes either the first target state of charge or the second target state of charge.
[0107] According to embodiments of this disclosure, if the train is in a target uphill environment, i.e., the intermediate value is the third intermediate value SOC. bal *Q*V bal +E drv Divide the third intermediate value by the reference value to obtain the target state of charge (SOC) as shown in formula (3). idea .
[0108] According to embodiments of this disclosure, if the train is in a target downhill environment, i.e., the intermediate value is the fourth intermediate value SOC. bal *Q*V bal -E brk Divide the third intermediate value by the reference value to obtain the target state of charge (SOC) as shown in formula (4). idea .
[0109] According to embodiments of this disclosure, determining the target matching interval of the actual state of charge at time i+1 in the state matching table includes the following operations:
[0110] The initial charge state interval in the state matching table is divided into multiple consecutive initial matching intervals based on multiple state endpoint values; the charging power of each initial matching interval is determined according to the actual charge state and the target charge state; and the target matching interval to which the actual charge state at time i+1 belongs is determined from the multiple initial matching intervals.
[0111] According to embodiments of this disclosure, the state endpoint values can be specifically set according to actual conditions. Based on the set state endpoint values, the initial state of charge interval in the state matching table is divided into multiple consecutive initial matching intervals. At the same time, for each initial matching interval, the charging power P corresponding to the initial matching interval is calculated according to the actual state of charge and the target state of charge corresponding to the interval, thereby obtaining a dynamically adjusted state matching table.
[0112] According to the embodiments of this disclosure, after the state matching table is dynamically adjusted, it is first determined which initial matching interval in the state matching table the actual state of charge (SOC) at time i+1 is located in, and then the initial matching interval is determined as the target matching interval to which the actual state of charge (SOC) at that time belongs. Then, the power battery can be charged using the charging power corresponding to the target matching interval.
[0113] According to embodiments of this disclosure, when the state endpoint values are SOC1, SOC2, and SOC3 from smallest to largest, the initial matching intervals are [0, SOC1), [SOC1, SOC2), [SOC2, SOC3), and [SOC3, 1], respectively.
[0114] According to embodiments of this disclosure, determining the charging power for each initial matching interval based on the actual state of charge and the target state of charge includes:
[0115] For the initial matching interval [0, SOC1), the proportional-integral result is determined as the charging power corresponding to the initial matching interval [0, SOC1), where the proportional-integral result is obtained by performing proportional-integral calculation on the actual state of charge and the target state of charge.
[0116] For the initial matching interval [SOC1, SOC2) or [SOC2, SOC3), the charging power corresponding to the initial matching interval [SOC1, SOC2) is determined based on the integral difference result and the idle power of the fuel cell. The integral difference result is generated based on the proportional integral result and the power step decrease difference.
[0117] For the initial matching interval [SOC3, 1], the idling power of the fuel cell is determined as the charging power corresponding to the initial matching interval [SOC3, 1].
[0118] Figure 2 A schematic diagram illustrating battery charging of a train under static conditions according to an embodiment of the present disclosure is shown.
[0119] like Figure 2 As shown, the first PI controller is used based on the actual state of charge and the target state of charge (SOC). idea Calculate the proportional-integral result P optThis allows for the calculation of the charging power P corresponding to different initial matching intervals, and the determination of the corresponding target charging power based on the actual state of charge. The fuel cell system then charges the power battery based on the target charging power.
[0120] In one embodiment, the state matching table may be as shown in Table 1:
[0121] Table 1
[0122]
[0123] According to the embodiments of this disclosure, taking the control strategy in Table 1 as an example, it is necessary to optimize the charging power of the power battery corresponding to the four initial matching intervals: SOC < SOC1, SOC1 ≤ SOC < SOC2, SOC2 ≤ SOC < SOC3, and SOC ≥ SOC3, while P1 > P2 > P3 > P4. The tuning of the maximum charging power introduces a linear controller with negative feedback of the power battery SOC. The charging power of the power battery in the static mode is controlled by the change of the battery SOC, thereby stabilizing the SOC of the power battery. The charging power of other initial matching intervals is obtained by successively decreasing, indicating that the smaller the SOC of the power battery, the greater the charging power in the corresponding static mode.
[0124] According to embodiments of this disclosure, referring to Figure 2 To calculate the charging power P, a PI controller can be used to perform proportional-integral calculations on the difference between the actual state of charge and the target state of charge, generating the maximum charging power of the power battery in static mode, i.e., the charging power in Table 1. Then, the target matching interval and charging power are obtained through the initial matching interval determination, and this charging power is attributed to the power output of the fuel cell system. The charging current of the power battery is I. chg =P ref / U bus , where P ref U represents the reference charging power of the power battery under static conditions of the train. bus This represents the DC bus voltage of the train, where U ref This indicates the reference charging voltage of the power battery when the train is in a static state.
[0125] According to embodiments of this disclosure, the reference output current I of the DC / DC converter of the fuel cell system ref The sum of the charging current of the power battery and the accessory current; the output current I of the DC / DC converter of the fuel cell system. out It must follow the reference current I refThis can be achieved by the second PI controller, i.e., the current inner loop controller. The error between the reference output current and the actual output current of the fuel cell system is used to generate the duty cycle required by the DC / DC converter through the current linear controller, which can be represented by Duty.
[0126] According to the embodiments of this disclosure, taking into account each initial matching interval, the charging power in the station stop state is calculated as shown in formula (5):
[0127]
[0128] Among them, P chg The charging power is the charging power P in the current station-stop state, as shown in Table 1; SOC i (i = 1, 2, 3, ...) represents the state endpoint values of the power battery's SOC range; P opt The output value of the proportional-integral controller, i.e., the proportional-integral result; P dcmin This represents the idle power of the fuel cell; ΔP is the power gradient difference in charging power, P opt -ΔP and P opt -N×ΔP mean integral difference result.
[0129] It should be noted that N in formula (5) can be set according to actual needs, for example, it can be 2.
[0130] Figure 3 A schematic diagram of the structure of a battery charging system according to an embodiment of the present disclosure is shown.
[0131] According to embodiments of this disclosure, the battery charging system includes a power battery, a fuel cell system, and an energy management controller.
[0132] The fuel cell system is used to charge the power battery under the control of the energy management controller.
[0133] The energy management controller is configured as follows:
[0134] Based on the state of charge of the power battery at time i and the traction and braking parameters, predict the state of charge parameters of the power battery at time i+1.
[0135] If the (i+1)th state of charge parameters satisfy the preset state parameter range and the driving environment is the target environment, the target state of charge is determined based on the set of charge parameters of the power battery, where,
[0136] The charge parameter set includes multiple battery parameters that characterize the physical properties of the power battery;
[0137] Determine the target matching interval of the actual state of charge of the power battery at time i+1 in the state matching table. The state matching table includes multiple initial matching intervals and the charging power corresponding to each initial matching interval. The charging power is determined based on the actual state of charge and the target state of charge.
[0138] The power battery is charged by the fuel cell system based on the target charging power corresponding to the target matching range.
[0139] It should be noted that the battery charging system part in the embodiments of this disclosure corresponds to the battery charging method part in the embodiments of this disclosure. For a detailed description of the battery charging system part, please refer to the battery charging method part, which will not be repeated here.
[0140] According to embodiments of this disclosure, by predicting the state of charge (SOC) parameters for the next moment based on the current SOC parameters and traction braking parameters, it is determined whether the SOC parameters for the next moment meet the preset parameter range and whether the driving environment is the target environment. The target SOC is then calculated based on the battery's charge parameter set. Based on the target SOC and the actual SOC, the charging power corresponding to each initial matching interval in the state matching table is calculated. The target charging power of the battery that matches its target matching interval is then selected to charge the battery. This optimizes the battery charging power in each initial matching interval under static train conditions, ensuring a longer operating time for the fuel cell system, reducing the number of start-stop cycles of the fuel cell system, and thus improving the durability of the fuel cell system and the economy of train operation.
[0141] Figure 3 A schematic diagram of a hybrid power system according to an embodiment of the present disclosure is shown. Figure 4 A schematic diagram illustrating the energy distribution of a hybrid power system according to an embodiment of the present disclosure is shown.
[0142] According to embodiments of this disclosure, a hybrid power system includes a fuel cell system, a converter, an inverter, and a traction motor connected in sequence. The hybrid power system also includes a power battery and an energy management controller. The power battery is connected to the converter and the inverter via a circuit. The energy management controller is connected to the fuel cell system, the converter, the inverter, the power battery, and the traction motor. The energy management controller charges the power battery according to the aforementioned battery charging method.
[0143] According to embodiments of this disclosure, taking the energy management and control strategy of a hydrogen-powered tram as an example, the fuel cell, DC / DC converter, and power battery work together to provide hybrid power for the tram. A schematic diagram of the hybrid power system structure is shown below. Figure 3As shown, the energy management controller coordinates the operating states of the fuel cell, power battery, and DC / DC converter. The energy distribution diagram is as follows. Figure 4 As shown.
[0144] in, Figure 4 In the middle, P dc V dc I dc These represent the power, voltage, and current output from the DC / DC converter in the fuel cell system, respectively, used to power the train. P bat V bat I bat I batmax These represent the power, voltage, current, and maximum current of the power battery providing power to the train or the fuel cell system charging the power battery, respectively. P aux This represents the sum of the power of all the train's accessories. P m V m and I m These represent the power, voltage, and current consumed by the train during its operation.
[0145] According to embodiments of this disclosure, during traction, the power is mainly supplied by the fuel cell, and the power battery works with the fuel cell to supply power to the train; during braking, the current through the braking resistor is controlled according to the output power of the fuel cell and the maximum allowable charging and discharging power of the power battery, so that the power battery can absorb a portion of the braking energy.
[0146] According to embodiments of this disclosure, the state of charge (SOC) parameters for the next moment are predicted based on the current SOC parameters and traction braking parameters. It is then determined whether the SOC parameters for the next moment meet a preset parameter range and whether the driving environment is the target environment. The target SOC is then calculated based on the battery's charge parameter set. Based on the target SOC and the actual SOC, the charging power corresponding to each initial matching interval in the state matching table is calculated. The target charging power of the battery that matches its target matching interval is selected to charge the battery. This optimizes the battery charging power in each initial matching interval under static train conditions, ensuring the longest possible fuel cell system operating time, reducing the number of start-stop cycles, and thus improving the durability of the fuel cell system and the economy of train operation.
[0147] According to embodiments of this disclosure, the train of this disclosure can be powered by a hybrid power system as described above.
[0148] According to embodiments of this disclosure, the train can be a hydrogen-powered high-speed train. Due to its high speed, long acceleration time, and high power output at constant speed, the proportion of fuel cells in the hydrogen power system of high-speed trains (speed ≥ 250 km / h) is higher than that of the power battery. If an energy management strategy based on a fixed SOC target value is used, it may affect the recovery of braking energy or traction acceleration performance. However, the battery charging method used in the train of this disclosure comprehensively considers the harsh operating conditions (e.g., long, steep inclines and declines), dynamically adjusting the target state of charge of the power battery to ensure the train's traction acceleration performance while increasing the braking energy recovery rate. Secondly, it employs closed-loop feedback control of the power battery SOC to precisely control the battery SOC usage range, ensuring it does not exceed the upper limit protection value of SOC that triggers the fuel cell system shutdown. up This invention enables fuel cells to operate without stopping under complex operating conditions, thereby extending their lifespan and improving the economic efficiency of train operation. Furthermore, the method disclosed herein has a simple control process, requires minimal engineering calculations, and facilitates controller integration and application.
[0149] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.
[0150] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.
Claims
1. A battery charging method, comprising: Based on the state-of-charge parameters and traction braking parameters of the power battery at time i, the (i+1)th state-of-charge parameters of the power battery at time i+1 are predicted; the (i+1)th state-of-charge parameters include the (i+1)th predicted upper limit value and the (i+1)th predicted lower limit value. Specifically, based on the state-of-charge parameters at time i and the traction braking parameters at time i, the (i+1)th state-of-charge parameters at time i+1 are predicted, including: A first intermediate value is generated based on the battery charge data during the traction braking process, the first electromotive force corresponding to the i-th state of charge, and the rated capacity of the power battery. The traction braking condition parameters include the battery charge data, the first electromotive force, and the rated capacity. Based on the first intermediate value and the i-th state of charge parameter, the (i+1)-th prediction upper limit value and the (i+1)-th prediction lower limit value are generated respectively. When the (i+1)th state of charge parameter satisfies the preset state parameter range and the driving environment is the target environment, the target state of charge is determined according to the set of charge parameters of the power battery. This includes determining the target state of charge according to the set of charge parameters of the power battery when the (i+1)th state of charge parameter is greater than the upper limit of the parameter range or less than the lower limit of the parameter range, and the driving environment is the target environment. The preset state parameter range includes an upper limit value and a lower limit value of the parameter range; the target environment includes a target uphill environment and a target downhill environment that meet preset conditions, the preset conditions include a length greater than a preset length and / or a slope greater than a preset slope; and the charge parameter set includes multiple battery parameters characterizing the physical performance of the power battery. The target matching interval of the actual state of charge of the power battery at time i+1 is determined in the state matching table, wherein the state matching table includes multiple initial matching intervals and a charging power corresponding to each initial matching interval, and the charging power is determined based on the actual state of charge and the target state of charge; The power battery is charged by the fuel cell system based on the target charging power corresponding to the target matching range.
2. The method according to claim 1, wherein, The charging power is determined by performing proportional-integral calculations on the actual state of charge and the target state of charge using a linear controller.
3. The method according to claim 1, further comprising: If the (i+1)th state of charge parameter satisfies the preset state parameter range but the driving environment is not the target environment, the state of charge balance value of the power battery is used to determine the target state of charge.
4. The method according to claim 1, wherein, Determining the target state of charge based on the set of charge parameters of the power battery includes: A second intermediate value is generated based on the state of charge balance value, the second electromotive force corresponding to the state of charge balance value, and the rated capacity of the power battery; Based on the second intermediate value and the battery power data during the traction process, a third intermediate value corresponding to the target uphill environment or a fourth intermediate value corresponding to the target downhill environment is generated. For any one of the third intermediate value and the fourth intermediate value, the target state of charge is generated based on the intermediate value and a reference value, wherein the reference value is generated based on the rated capacity and the third electromotive force corresponding to the i-th state of charge.
5. The method according to claim 4, wherein, Generating the target state of charge based on the intermediate value and the reference value includes: When the intermediate value is the third intermediate value, a first target state of charge under the target uphill environment is generated based on the third intermediate value and the reference value; or When the intermediate value is the fourth intermediate value, a second target state of charge under the target downhill environment is generated based on the fourth intermediate value and the reference value, wherein the target state of charge includes the first target state of charge or the second target state of charge.
6. The method according to claim 1, wherein, Determine the target matching interval of the actual state of charge at time i+1 in the state matching table, including: The initial charged state interval in the state matching table is divided into multiple consecutive initial matching intervals based on multiple state endpoint values; The charging power for each initial matching interval is determined based on the actual state of charge and the target state of charge. The target matching interval to which the actual state of charge at time i+1 belongs is determined from the plurality of initial matching intervals.
7. The method according to claim 6, wherein when the state endpoint values are SOC1, SOC2, and SOC3 in ascending order, the initial matching intervals are [0, SOC1), [SOC1, SOC2), [SOC2, SOC3), and [SOC3, 1], respectively; in, Determining the charging power for each initial matching interval based on the actual state of charge and the target state of charge includes: For the initial matching interval [0, SOC1), the proportional-integral result is determined as the charging power corresponding to the initial matching interval [0, SOC1), wherein the proportional-integral result is obtained by performing proportional-integral operation on the actual state of charge and the target state of charge; For the initial matching interval [SOC1, SOC2), the charging power corresponding to the initial matching interval [SOC1, SOC2) is determined based on the integral difference result and the idle power of the fuel cell, wherein the integral difference result is generated based on the proportional integral result and the power step decrease difference. For the initial matching interval [SOC3, 1], the idling power of the fuel cell is determined as the charging power corresponding to the initial matching interval [SOC3, 1].
8. A battery charging system, comprising: Power battery; A fuel cell system for charging the power battery under the control of an energy management controller; The energy management controller is configured as follows: Based on the state-of-charge parameters and traction braking parameters of the power battery at time i, predict the (i+1)th state-of-charge parameters of the power battery at time i+1; the (i+1)th state-of-charge parameters include the (i+1)th predicted upper limit value and the (i+1)th predicted lower limit value. Specifically, based on the state-of-charge parameters at time i and the traction braking parameters at time i, the (i+1)th state-of-charge parameters at time i+1 are predicted, including: A first intermediate value is generated based on the battery charge data during the traction braking process, the first electromotive force corresponding to the i-th state of charge, and the rated capacity of the power battery. The traction braking condition parameters include the battery charge data, the first electromotive force, and the rated capacity. Based on the first intermediate value and the i-th state of charge parameter, the (i+1)-th prediction upper limit value and the (i+1)-th prediction lower limit value are generated respectively. When the (i+1)th state of charge parameter satisfies the preset state parameter range and the driving environment is the target environment, the target state of charge is determined according to the set of charge parameters of the power battery. This includes determining the target state of charge according to the set of charge parameters of the power battery when the (i+1)th state of charge parameter is greater than the upper limit of the parameter range or less than the lower limit of the parameter range, and the driving environment is the target environment. The preset state parameter range includes an upper limit value and a lower limit value of the parameter range; the target environment includes a target uphill environment and a target downhill environment that meet preset conditions, the preset conditions include a length greater than a preset length and / or a slope greater than a preset slope; and the charge parameter set includes multiple battery parameters characterizing the physical performance of the power battery. The target matching interval of the actual state of charge of the power battery at time i+1 is determined in the state matching table, wherein the state matching table includes multiple initial matching intervals and a charging power corresponding to each initial matching interval, and the charging power is determined based on the actual state of charge and the target state of charge; The power battery is charged by the fuel cell system based on the target charging power corresponding to the target matching range.
9. A hybrid power system, comprising: The fuel cell system, converter, inverter, and traction motor are connected in sequence. A power battery, wherein the power battery is connected in a line between the converter and the inverter; An energy management controller is connected to the fuel cell system, the converter, the inverter, the power battery, and the traction motor, respectively. The energy management controller charges the power battery according to any one of the battery charging methods described in claims 1 to 7.
10. A type of train, wherein, The train is powered by the hybrid power system described in claim 9.