System and method for judging whether ion filter needs to be replaced or not

Abstract

The invention provides a system and a method for judging whether to replace an ion filter or not. The system for determining whether to replace an ion filter includes: a measurement unit that measures an insulation resistance value of a fuel cell stack during operation of a vehicle or a system; and a control unit that determines whether or not to replace the ion filter on the basis of the insulation resistance values, the control unit calculating a movement value based on the insulation resistance values measured in each of a plurality of cycles using the start to end of operation of the vehicle or system as one cycle, and changing the ion filter. The moving value is a moving average value or a moving intermediate value for an average value or an intermediate value of the insulation resistance values, and the control unit determines whether to replace the ion filter on the basis of at least one of the magnitude of the moving value and the rate of change of the moving value.

Description

Technical Field

[0001] The present invention relates to a system and method for determining whether to replace an ion filter, which determines whether to replace the ion filter by processing the measured insulation resistance value. Background Art

[0002] A fuel cell is a battery that directly converts chemical energy generated by the oxidation of a fuel into electrical energy and belongs to a power generation device. Basically, it is the same as a chemical battery in that it utilizes oxidation and reduction reactions, but different from a chemical battery in which the battery reaction occurs inside a closed system in that the reactants of the fuel cell are continuously supplied from the outside, and the reaction products are continuously discharged outside the system. In recent years, fuel cell power generation systems have been put into practical use, and since the reaction product of the fuel cell is pure water, related research is actively underway to use it as an energy source for environmentally friendly vehicles or power generation systems.

[0003] Generally, a fuel cell system includes a cooling system for controlling the temperature of the fuel cell and a drive system for driving a vehicle or a power generation system through the fuel cell. The cooling system includes a pipe for circulating a coolant inside the fuel cell and a radiator for controlling the temperature of the coolant; the drive system includes a motor provided in the vehicle or system that is driven by the electrical energy generated by the fuel cell.

[0004] On the other hand, in a vehicle (hereinafter, referred to as a "fuel cell vehicle") or system to which a fuel cell system is applied, an insulation resistance is generated, such as a resistance caused by various electrical components constituting the fuel cell system and a resistance caused by the coolant. For the safety of the driver, the insulation resistance of the fuel cell system needs to be maintained above a specific value. Therefore, an ion filter is applied in the fuel cell system to remove ions in the coolant. The ion filter is a consumable that needs to be replaced after a certain period of time or when the running time of the vehicle or system increases. When replacing the ion filter, it is important to determine the correct replacement cycle, and for this purpose, it is necessary to measure the insulation resistance of the fuel cell system or measure the conductivity of the coolant.

[0005] However, the insulation resistance value may change due to various reasons such as component failure, short circuit, and coolant contamination in addition to the reduced durability of the ion filter. Therefore, when determining whether to replace the ion filter based on the insulation resistance value, there is a problem that it is difficult to accurately determine the correct replacement timing of the ion filter. In addition, when a sensor for measuring conductivity is applied to the fuel cell system, although the durability of the ion filter that removes ions from the coolant can be directly confirmed, the problem is that the sensor for measuring conductivity is relatively expensive. Summary of the Invention

[0006] An object of the present invention is to provide a system and method for accurately determining whether an ion filter needs to be replaced by measuring the insulation resistance without using a conductivity sensor.

[0007] Another object of the present invention is to provide a system and method for determining whether to replace an ion filter as follows: by analyzing the durability degradation mode of the ion filter and performing a reliability analysis on the durability degradation mode of the ion filter, thereby improving the reliability of the determination of ion filter replacement.

[0008] Provide a system for determining whether to replace an ion filter based on an embodiment of the present invention. The system for determining whether to replace an ion filter includes: a measurement unit that measures the insulation resistance value of a fuel cell stack during the operation of a vehicle or a system; and a control unit that determines whether to replace the ion filter based on the insulation resistance value. The control unit takes the start to the end of the operation of the vehicle or the system as one cycle, and calculates a moving value based on the insulation resistance values measured in multiple cycles. The moving value refers to a moving average value or a moving median value with respect to the average value or the median value of the insulation resistance value. The control unit determines whether to replace the ion filter based on at least one of the magnitude of the moving value or the change rate of the moving value.

[0009] According to an example, the control unit determines whether a first condition and a second condition are satisfied. The first condition is to determine whether the magnitude of the moving value is below a preset threshold, and the second condition is to determine whether the change rate of the moving value is less than a preset change rate. When both the first condition and the second condition are satisfied, the control unit determines that the ion filter needs to be replaced.

[0010] According to an example, the control unit determines whether a third condition is satisfied. The third condition is to count the cases where the insulation resistance value measured within one cycle from the start to the end of the operation of the vehicle or the system is within a specific range, and determine whether the total count is greater than a preset count value. When the first condition, the second condition, and the third condition are all satisfied, the control unit determines that the ion filter needs to be replaced.

[0011] According to an example, when the number of insulation resistance values measured within one cycle is less than or equal to a preset number, the control unit does not determine whether the third condition is satisfied based on the insulation resistance value measured within the corresponding cycle.

[0012] According to an example, the control unit determines whether the total count of whether the insulation resistance values measured in a plurality of consecutive cycles are within the specific range is greater than a preset count value.

[0013] According to one example, the above-mentioned moving value is calculated based on a plurality of expression values obtained by encoding the average value or the median value of the insulation resistance values measured within one cycle using single-digit numbers.

[0014] According to one example, 5 expression values are converted into a 5-digit number and stored, or 10 expression values are converted into a 10-digit number and stored, or 20 expression values are converted into a 20-digit number and stored.

[0015] According to one example, a preset first number of expression values are stored, the above-mentioned control unit calculates the above-mentioned moving value based on the stored preset first number of expression values, and the above-mentioned control unit determines whether to replace the ion filter based on a continuous preset second number of moving values, and the preset first number is a number larger than the preset second number.

[0016] According to one example, the above-mentioned control unit compares the latest moving value among the preset second number of moving values or the average magnitude of the above-mentioned moving value with a preset threshold value to determine whether the first condition is satisfied.

[0017] According to one example, the above-mentioned control unit compares the difference between the latest moving value among the preset second number of moving values and a determined value based on past moving values with a preset difference value to determine whether the second condition is satisfied.

[0018] According to one example, when the difference between the above-mentioned latest moving value and the above-mentioned determined value is larger than the preset difference value, the above-mentioned control unit determines that there is an error in the measurement of the insulation resistance value, and interrupts the process of determining whether to replace the ion filter within a certain period of time.

[0019] According to one example, the above-mentioned control unit compares the change rate of the preset second number of moving values with a preset change rate to determine whether the second condition is satisfied.

[0020] According to one example, only when both the first condition and the second condition are satisfied, the above-mentioned control unit determines that the ion filter needs to be replaced.

[0021] In the method for determining whether to replace the ion filter implemented by the control unit for determining whether to replace the ion filter according to an embodiment of the present invention, it includes: calculating the average value or the median value of the insulation resistance values measured from the start to the end of the operation of the vehicle or system as one cycle; deriving a plurality of expression values obtained by encoding the average value or the median value of the insulation resistance values measured in a plurality of cycles using single-digit numbers; calculating the moving value for the above-mentioned plurality of expression values; and determining whether to replace the ion filter based on at least one of the magnitudes of at least one of the above-mentioned moving values or the change rate of the above-mentioned moving values, where the above-mentioned moving value refers to the moving average value or the moving median value of the average value or the median value of the above-mentioned insulation resistance value.

[0022] According to one example, the steps of determining whether to replace the ion filter include: determining whether the first condition and the second condition are satisfied. The first condition is to determine whether the magnitude of the movement value is below a preset threshold value, and the second condition is to determine whether the change rate of the movement value is less than a preset change rate. When both the first condition and the second condition are satisfied, it is determined that the ion filter needs to be replaced.

[0023] According to one example, the steps of determining whether to replace the ion filter include: determining whether the third condition is satisfied. The third condition is to count the cases where the insulation resistance value measured within a cycle from the start to the end of the operation of the vehicle or system is within a specific range, and to determine whether the total count is larger than a preset count value. When the first condition, the second condition, and the third condition are all satisfied, it is determined that the ion filter needs to be replaced.

[0024] According to one example, the steps of calculating the movement value include: the step of calculating the movement value according to a preset first quantity of expression values; and the step of determining whether to replace the ion filter according to a continuous preset second quantity of movement values.

[0025] According to one example, the latest movement value among the preset second quantity of movement values or the average magnitude of the movement value is compared with a preset threshold value to determine whether the first condition is satisfied.

[0026] According to one example, the difference between the latest movement value among the preset second quantity of movement values and a determined value based on the previous movement values is compared with a preset difference value, or the change rate of the preset second quantity of movement values is compared with a preset change rate to determine whether the second condition is satisfied.

[0027] In a storage medium storing computer-readable instructions (instructions) based on an embodiment of the present invention, the instructions are executed by a processor, and the processor executes: an operation of calculating the average value or the median value of the insulation resistance values measured with the start to the end of the operation of the vehicle or system as one cycle; an operation of deriving a plurality of expression values obtained by encoding the average value or the median value of the insulation resistance values measured in a plurality of cycles with a single-digit number; an operation of calculating the movement value for the plurality of expression values; and an operation of determining whether to replace the ion filter according to at least one of the magnitudes of at least one of the movement values or at least one of the change rates of the movement values. The movement value refers to the moving average value or the moving median value of the average value or the median value of the insulation resistance values.

[0028] According to an embodiment of the present invention, by determining whether the measured insulation resistance value and the data obtained by post-processing the insulation resistance value satisfy three conditions, it is possible to accurately determine whether the ion filter needs to be replaced, thereby eliminating the need to rely on a conductivity sensor.

[0029] According to an embodiment of the present invention, the control unit can distinguish a situation where the insulation resistance value changes sharply due to a failure of a component other than the ion filter, and thus can improve the reliability of the replacement determination of the ion filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a block diagram for explaining a system for determining whether to replace an ion filter based on an embodiment of the present invention.

[0031] Figure 2 is a flowchart for explaining a method for determining whether the first condition and the second condition are satisfied in a method for determining whether to replace an ion filter based on an embodiment of the present invention.

[0032] Figure 3 is a flowchart for explaining a method for determining whether the third condition is satisfied in a method for determining whether to replace an ion filter based on an embodiment of the present invention.

[0033] Figure 4 is a diagram for explaining a method for deriving an expression value based on an embodiment of the present invention.

[0034] Figure 5 is a graph for explaining a method for determining whether to replace an ion filter when the performance of the ion filter deteriorates based on an embodiment of the present invention.

[0035] Figure 6 is a graph for explaining a method for determining whether to replace an ion filter caused by an error of a component constituting a fuel cell system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The advantages and features of the present invention, and the methods for achieving these advantages and features, will be described in detail through the following embodiments and the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in a variety of different ways. The embodiments disclosed below are only intended to make the disclosure of the present invention more complete, so that those skilled in the art can fully understand the scope of the present invention. The present invention is only defined by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0037] The terms such as "... unit", "... unit", and "... module" used in this specification refer to a unit that processes at least one function or operation, and can be implemented by hardware, software, or a combination of hardware and software.

[0038] In addition, in this specification, the names of components are adopted in the form of "first", "second", etc. only to distinguish their names, and it does not mean that a specific order must be followed in the subsequent description.

[0039] The detailed description is intended to illustrate the present invention by way of example. The content described below only shows the preferred embodiments of the present invention. In fact, the present invention can be used in various other combinations, variations and environments. That is, changes or modifications can be made within the scope of the inventive concept disclosed in this specification, the scope equivalent to the specific disclosure content, and / or the scope of the technology or knowledge in the art. The specific embodiments describe the best state of implementing the technical idea of the present invention, and various modifications can also be made according to the specific application fields and uses of the present invention. Therefore, the detailed description of the present invention does not limit the present invention to the disclosed implementation state. In addition, the claims should also be interpreted as including other implementation states.

[0040] Figure 1 It is a block diagram for explaining a system for judging whether to replace an ion filter based on an embodiment of the present invention.

[0041] Refer to Figure 1 , the system for judging whether to replace the ion filter can be implemented by the measuring unit 100, the control unit 200 and the output unit 300. The judging system for judging whether to replace the ion filter can be applied to the thermal management system of a fuel cell. In other words, the system for judging whether to replace the ion filter can be applied to a vehicle or a system using a fuel cell stack as an energy source. The thermal management system can release the heat generated by the electrochemical reaction of the fuel cell stack to the outside, thereby optimizing the operating temperature of the fuel cell stack, and can perform a water management function. In order to remove ions in the coolant applied to the thermal management system, an ion filter can be used, and the system for judging whether to replace the ion filter refers to a system for judging whether the ion filter needs to be replaced.

[0042] The measuring unit 100 can measure the insulation resistance value of the fuel cell stack when the vehicle or the system is running. The measuring unit 100 can be an FSVM (Fuel cell stack voltage management) or a BMS (Battery Management System) for measuring the insulation resistance value of the fuel cell stack. The insulation resistance value can be measured as a value between 0 and 1000. Generally, the insulation resistance value can be measured in units of kiloohms (kΩ) with a magnitude of several hundred. The start and end of the operation of the vehicle or the system can be defined as a cycle, and the measuring unit 100 can continuously measure the insulation resistance value within one cycle.

[0043] As an example, the measuring unit 100 can be connected to the output terminal of the fuel cell stack to measure the insulation resistance of the vehicle or system. Specifically, the measuring unit 100 can measure the voltage between the high-voltage terminal and the ground terminal of the fuel cell stack. At this time, the high-voltage terminal can refer to the part in the fuel cell stack that is not surrounded by an insulator. The measuring unit 100 can measure the combined insulation resistance, which is the sum of the insulation resistances of a plurality of electrical components and the coolant connected in parallel with the high-voltage terminal and the ground terminal of the fuel cell stack. The above example is just one method, and the methods for measuring insulation resistance can be various and are not limited to specific embodiments.

[0044] The insulation resistance value of the fuel cell stack applied to the vehicle or system may fluctuate for various reasons. For example, when the internal humidity of the fuel cell stack rises, the insulation resistance value may decrease; when the coolant temperature rises, the conductivity of the coolant increases, and thus the insulation resistance value may decrease. In addition, when the life of the ion filter expires or the amount of ions in the coolant increases, the conductivity of the coolant rises, and thus the insulation resistance value may also decrease. In addition, when high-voltage components such as motors, air compressors, and pumps fail and the insulation of the high-voltage components is damaged, the insulation resistance value will also decrease. The measured insulation resistance value can be transmitted to the control unit 200.

[0045] The control unit 200 can determine whether to replace the ion filter (whether the ion filter needs to be replaced) based on the insulation resistance value measured by the measuring unit 100. Specifically, taking the start to the end of the operation of the vehicle or system as one cycle, the control unit 200 can calculate the moving average or moving median of the average value or median value of the insulation resistance values measured in multiple cycles, and then determine whether to replace the ion filter based on at least one of the magnitude of the moving average, the change rate of the moving average, the magnitude of the moving value, or the change rate of the moving value. The moving average or moving median can be defined as the moving value. In other words, the moving value can represent the moving average or moving median of the average value or median value of the insulation resistance value. For example, the control unit 200 can be an FCU (Fuel Control Unit) for controlling various components connected to the fuel cell system.

[0046] In order to determine whether to replace the ion filter, a process of data processing of the measured insulation resistance value may be required. During the data processing process, the average value or median value of the multiple insulation resistance values measured in one cycle can be calculated, and the average value or median value of the multiple insulation resistance values can be expressed by a single-digit number. That is, the result of encoding the average value or median value of the multiple insulation resistance values with a single-digit number can be defined as the expression value, and an expression value can be derived for each cycle. For example, the single-digit number can be a number expressed from 0 to 5, but the specific number is not limited to this.

[0047] The control unit 200 can calculate a plurality of moving values for a plurality of expression values measured in a plurality of cycles. That is, the control unit 200 can calculate a plurality of moving intermediate values or a plurality of moving average values for the plurality of expression values. The control unit 200 can derive a moving value for a preset first number of expression values and can store a preset second number of moving values. The preset first number can be a number larger than the preset second number. For example, the preset first number can be 9, and the preset second number can be 5, but it is not specifically limited thereto. The control unit 200 can use the second number of moving values to determine whether to replace the ion filter.

[0048] When at least one of the three conditions is satisfied, the control unit 200 can determine that the ion filter needs to be replaced. Preferably, the control unit 200 determines that the ion filter needs to be replaced only when all three conditions are satisfied.

[0049] The first condition can be to determine whether the magnitude of the latest moving value among the second number of moving values is below a preset threshold. The latest moving value is a moving value derived from a plurality of insulation resistance values in one cycle most recently measured by the measurement unit 100. For example, the preset threshold can be 4, but the specific value is not specifically limited.

[0050] The second condition can be to determine whether the change rate of the second number of moving values is less than a preset change rate, or to determine whether the difference between the latest moving value among the second number of moving values and a determined value based on a plurality of past moving values is less than a preset difference. As an example, the determined value can be a moving value derived from a plurality of insulation resistance values in one cycle measured earliest among the second number of moving values stored by the control unit 200. As another example, the determined value can be the average value of the second number of moving values stored by the control unit 200 except for the latest moving value. As another example, the determined value can be any moving value among the second number of moving values stored by the control unit 200 except for the latest moving value. For example, the preset change rate and the preset difference can be 1, but the specific values are not specifically limited.

[0051] The third condition can be to count the cases where a plurality of insulation resistance values in one cycle most recently measured are within a specific range and to determine whether the total count exceeds a preset count value. For example, the specific range can be defined as 86 kΩ to 140 kΩ, and the preset count value can be 40, but the specific values are not specifically limited.

[0052] The first condition is a condition for determining whether the durability of the ion filter is decreasing. The second condition is a condition for determining whether there is an error in the ion filter replacement determination. The second condition is a condition for confirming whether there is a drastic change in the insulation resistance value due to a failure of a component other than the ion filter. The third condition may be a condition for directly confirming that when a generally low insulation resistance value is detected, the ion filter is indeed unable to effectively perform the function of removing ions. The control unit 200 can consider these three conditions to determine whether to replace the ion filter.

[0053] The measurement unit 100 and the control unit 200 may each include a processor and a memory. The processor can be composed of more than one chip and may include a central processing unit (CPU) of a computing device, a general-purpose graphics processing unit (GPGPU), a tensor processing unit (TPU), and an application processor (AP) and other processors for data analysis and deep learning. One or more processors can execute control according to predefined operation rules or artificial intelligence models stored in the memory to process input data. When one or more processors are artificial intelligence dedicated processors, the artificial intelligence dedicated processors can be designed as hardware structures dedicated to processing specific artificial intelligence models.

[0054] The processor executes the system for determining whether to replace the ion filter according to the present embodiment by reading a computer program or instruction stored in the memory. The memory can store various information required for the system for determining whether to replace the ion filter according to the embodiments of the present invention. For example, a plurality of insulation resistance values measured by the measurement unit 100, a plurality of expression values stored by the control unit 200, and a plurality of movement values can be stored in the memory.

[0055] The memory can include at least one type of storage medium such as flash memory type, hard disk type, multimedia card micro type, card type memory (e.g., SD or XD memory, etc.), Random Access Memory (RAM), Static Random Access Memory (SRAM), Read-Only Memory (ROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Programmable Read-Only Memory (PROM), magnetic memory, magnetic disk, and optical disk. In addition, the memory can include any form of computer-readable recording medium known in the technical field to which the present invention pertains. The above description of the memory is only an example, and the present invention is not limited thereto.

[0056] The output unit 300 can notify the driver of the situation regarding whether the ion filter needs to be replaced. When it is determined by the control unit 200 that the ion filter needs to be replaced, the output unit 300 can notify the driver through a message, warning light, and alarm sound. In addition, when notifying the situation that there is a problem in the fuel cell system where the insulation resistance value is below a certain level, the output unit 300 can also output a message, warning light, and alarm sound.

[0057] According to an embodiment of the present invention, it is determined whether the ion filter needs to be replaced based on whether the measured insulation resistance value and the data obtained by post-processing the insulation resistance value satisfy three conditions, so that it is possible to accurately determine whether the ion filter needs to be replaced even without a conductivity sensor.

[0058] According to an embodiment of the present invention, the control unit 200 can distinguish the situation where the insulation resistance value changes sharply due to a failure of a component other than the ion filter, so that the reliability of the replacement determination of the ion filter can be improved.

[0059] Figure 2 It is a flowchart illustrating a method for determining whether the first condition and the second condition are satisfied in the method for determining whether to replace the ion filter based on an embodiment of the present invention.

[0060] Refer to Figure 1 and Figure 2, the measurement unit 100 takes the period from the start to the end of the operation of the vehicle or system as one cycle, and can continuously measure multiple insulation resistance values within one cycle (S200). The start and end of the operation can represent the start and stop of the vehicle or the power-on and power-off of the system. The multiple insulation resistance values can be measured at preset time intervals. However, if the number of multiple insulation resistance values measured within one cycle is less than the preset number of times, the measurement unit 100 can choose not to store the insulation resistance values measured within the corresponding cycle. Additionally, if the number of multiple insulation resistance values measured within one cycle is less than the preset number of times, the control unit 200 can refrain from using the multiple insulation resistance values measured within the corresponding cycle during the process of judging the replacement of the ion filter. For example, the preset number of times can be 40 times, but it is not specifically limited to this. The situation where the number of multiple insulation resistance values measured within one cycle is less than the preset number of times means that the operation time of the vehicle or system is short. To avoid errors in judging the replacement of the ion filter by using relatively less data measured during a short operation time, the control unit 200 can refrain from using the multiple insulation resistance values measured within the corresponding cycle during the process of judging the replacement of the ion filter.

[0061] The measurement unit 100 can transmit the multiple measured insulation resistance values to the control unit 200. The control unit 200 can perform preprocessing on all the received values received from the measurement unit 100 (S210). The control unit 200 can remove the null values and error values among the multiple measured insulation resistance values.

[0062] The control unit 200 can calculate the average value or the median value of all the received values, and can derive an expression value representing the average value or the median value in a specific pattern (S220). The control unit 200 can calculate the average value or the median value of the multiple insulation resistance values measured within one cycle, and can derive multiple expression values encoding the average value or the median value with single-digit numbers.

[0063] As an example, the expression value can be represented by 0 to 5. The control unit 200 can derive expression values in multiple cycles respectively. The 5 expression values can be converted into a 5-digit number (ten-thousand unit), and can be stored in a 16-bit variable divided into 2-byte storage space. The maximum value of the number represented by the 16-bit variable can be 65535. Since the expression value cannot be represented by a number greater than 5, the 5-digit number after converting the 5 expression values must be less than 65535. Therefore, by storing the expression values derived in 5 cycles as one number, the storage space for storing data is minimized.

[0064] As another example, the expression value can be expressed as 0 to 3. The control unit 200 can derive the expression value separately in multiple cycles. Ten expression values can be converted into a 10-digit number (in billions) and stored in a 32-bit variable divided into 4 bytes (byte) of storage space. The maximum value of the number represented by the 32-bit variable can be 4,294,967,295.

[0065] As another example, the expression value can be expressed as 0 to 1. The control unit 200 can derive the expression value separately in multiple cycles. Twenty expression values can be converted into a 20-digit number (in quadrillions) and stored in a 64-bit variable divided into 8 bytes (byte) of storage space. The maximum value of the number represented by the 64-bit variable can be 18,446,744,073,709,551,615.

[0066] The control unit 200 can store a preset first number of expression values. When calculating a new expression value, the control unit 200 can delete the earliest expression value. For example, the preset first number can be 9, but it is not specifically limited thereto. The control unit 200 can calculate the moving value (S230) of the stored first number of expression values. That is, the control unit 200 can calculate the moving median or moving average of the first number of expression values. For example, when the moving value is the moving median, the control unit 200 can determine the expression value of the middle size among the first number of expression values as the moving median. In order to use the moving median instead of the average, an odd number of expression values can be used.

[0067] The control unit 200 can store a preset second number of moving values (S240). That is, the control unit 200 can store a preset second number of moving medians or moving averages. When calculating a new moving value, the control unit 200 can delete the earliest moving value. For example, the preset second number can be 5, but it is not specifically limited thereto.

[0068] The control unit 200 can compare the magnitude of any one of the plurality of moving values with a preset threshold value to confirm the durability degradation mode of the ion filter (S250). In other words, the control unit 200 can compare the magnitude of any one of the plurality of moving average values or the magnitude of any one of the plurality of moving intermediate values with a preset threshold value to confirm the durability degradation mode of the ion filter. Preferably, the control unit 200 can determine whether the magnitude of the latest moving value is less than or equal to the preset threshold value. For example, the preset threshold value can be 4, but it is not specifically limited thereto. When the magnitude of the latest moving value is greater than the preset threshold value, the control unit 200 can determine that the durability of the ion filter is not in the degradation mode. Therefore, the control unit 200 can continuously compare the magnitude of the latest moving value with the preset threshold value through the processing of the plurality of insulation resistance values measured by the measurement unit 100. Different from the above example, the control unit 200 can also compare the average value of the plurality of moving values with the preset threshold value to confirm the durability degradation mode of the ion filter.

[0069] When the magnitude of the latest moving value is less than or equal to the preset threshold value, the control unit 200 can determine that the durability of the ion filter is in the degradation mode (S255). In other words, when the magnitude of the latest moving value is less than the preset threshold value, the control unit 200 can determine that the ion filter is in a state where it cannot perform its original function.

[0070] The control unit 200 can compare the change rate of the plurality of moving values with a preset change rate to confirm whether there is an error in the ion filter judgment process (S260). In other words, the control unit 200 can compare the change rate of the plurality of moving intermediate values or the change rate of the plurality of moving average values with a preset change rate to confirm whether there is an error in the ion filter judgment process. The control unit 200 can determine whether the change rate of the plurality of moving values is less than the preset change rate, or whether the difference between the latest moving value among the second number of moving values and the determined value based on the previous plurality of moving values is less than the preset difference. For example, the preset change rate and the preset difference can be 1, but the specific values are not specifically limited. The change rate of the plurality of moving values is confirmed because a sharp change in the insulation resistance value is likely to be caused by other components or other factors other than the ion filter.

[0071] When the change rate of multiple moving values is equal to or greater than a preset change rate, or the difference between the latest moving value and the determined value is equal to or greater than a preset difference, the control unit 200 can determine that the sharp change in the insulation resistance value is caused by factors other than the ion filter, and can stop judging the mode of the ion filter for a certain period of time (S262). For example, the certain period of time can be about 20 cycles when taking the start to end of the operation of the vehicle or system as one cycle, but it is not specifically limited to this. However, the measurement of the insulation resistance value by the measurement unit 100 can also continue within the certain period of time. Stopping the judgment of the ion filter mode within a certain period of time is because, due to the sharp change in the insulation resistance value, there is a high possibility that the data measured during the time until the driver completes the inspection of the vehicle or system based on the warning message output by the output unit 300 is incorrect data. After the elapse of the certain period of time, the control unit 200 can compare the change rate of the multiple moving values with the preset change rate again, or compare the difference between the latest moving value and the determined value with the preset difference.

[0072] When the change rate of multiple moving values is less than the preset change rate or the difference between the latest moving value and the determined value is less than the preset difference, the control unit 200 can confirm that there is no error in the ion filter judgment (S265). That is, since the insulation resistance value has not changed sharply, the control unit 200 can determine that the result of judging the durability mode of the ion filter is reliable.

[0073] When the control unit 200 confirms the durability degradation mode of the ion filter and at the same time confirms that there is no error in the ion filter judgment, it can determine that the ion filter needs to be replaced (S270). When the first condition for confirming the durability degradation mode of the ion filter and the second condition for confirming that there is no error in the ion filter judgment are met, the control unit 200 can determine that the ion filter needs to be replaced. The second condition can be a condition for confirming whether the result of judging the durability degradation mode of the ion filter according to the first condition is reliable.

[0074] According to an embodiment of the present invention, after confirming the durability degradation mode of the ion filter and going through the process of verifying the reliability of the durability degradation mode of the ion filter, it is determined whether to replace the ion filter, thereby improving the reliability of the ion filter replacement judgment.

[0075] Figure 3 It is a flowchart showing a method for determining whether the third condition is satisfied in the method for determining whether to replace the ion filter based on an embodiment of the present invention.

[0076] Refer to Figure 1 and Figure 3, the measuring unit 100 can take the start to the end of the operation of the vehicle or system as one cycle and measure the insulation resistance value within one cycle. The multiple insulation resistance values measured by the measuring unit 100 can be transmitted to the control unit 200 (S300).

[0077] When the insulation resistance value received by the control unit 200 is within a specific range, the control unit 200 can perform counting (S310). For example, the specific range can be from 86 kΩ to 140 kΩ, but it is not specifically limited to this. When the number of multiple insulation resistance values measured within one cycle is less than or equal to a preset number, the control unit 200 can not judge whether the ion filter needs to be replaced based on the multiple insulation resistance values measured within this cycle. For example, the preset number can be 40 times, but the specific number is not specifically limited.

[0078] The control unit 200 can count the cases where the insulation resistance value within one cycle of the most recently measured is within a specific range, and judge whether the total count is greater than a preset count value (S320). That is, the third condition can be to count the cases where the insulation resistance value within one cycle of the most recently measured is within a specific range, and judge whether the total count is greater than a preset count value. For example, the preset count value can be 40, but the specific value is not specifically limited. When the total count is less than or equal to the preset count value, the control unit 200 judges that there is no problem with the multiple insulation resistance values within the corresponding cycle, and can end the ion filter replacement judgment. However, in the next cycle, the control unit 200 can still judge whether the multiple insulation resistance values are within a specific range.

[0079] When the total count is greater than the preset count value, the control unit 200 judges that there is a problem with the multiple insulation resistance values within the corresponding cycle, and can judge that it is necessary to replace the ion filter. As another example, the control unit 200 can also compare the multiple insulation resistance values measured in two or more consecutive cycles that are not one cycle with a specific range to judge whether the third condition is met. The control unit 200 can judge whether the total count of the cases where the insulation resistance values measured in consecutive multiple cycles are within a specific range is greater than a preset count value. At this time, the multiple cycles can be two to four consecutive cycles, but it is not specifically limited to this. The control unit 200 can judge whether the third condition is met in multiple cycles, so as to avoid errors in the ion filter replacement judgment. When the first condition, the second condition, and the third condition are all met, the control unit 200 can judge that the ion filter needs to be replaced. However, when any one or at least two of the first condition, the second condition, and the third condition are met, the control unit 200 can also judge that the ion filter needs to be replaced (S330).

[0080] Figure 4This is a diagram for explaining a method of deriving an expression value based on an embodiment of the present invention. Figure 4 This is a diagram for explaining the case where the variable of the control unit is 16 bits.

[0081] Refer to Figure 1 and Figure 4 Refer to FIGS. and, the control unit 200 can perform data processing on a plurality of insulation resistance values measured by the measurement unit 100. The control unit 200 can encode the measured plurality of insulation resistance values using bit masking to minimize the data storage space. The control unit 200 can express the average value or the median value of the plurality of insulation resistance values measured in one cycle as a single-digit number. The value expressed as a single-digit number can be defined as an expression value. For example, the single-digit number can be from 0 to 5.

[0082] As an example, the control unit 200 can derive an expression value by carrying the hundreds digit of the average value or the median value of the insulation resistance value upward and limiting the maximum value to 5. When the average value or the median value of the insulation resistance value is 258, the expression value can be expressed as 3. When the average value or the median value of the insulation resistance value is 72, the expression value can be expressed as 1. When the average value or the median value of the insulation resistance value is 854, the expression value can be expressed as 5 which is set as the maximum value. When the average value or the median value of the insulation resistance value is 356, the expression value can be expressed as 4. The plurality of average values or the plurality of median values of the insulation resistance values measured in 5 cycles can be expressed as 5, 3, 1, 5, 4, and the 5 expression values can be converted into a 5-digit number and stored in a 16-bit variable divided into a 2-byte storage space. In other words, the plurality of average values or the plurality of median values of the insulation resistance values measured in 5 cycles can be stored as a single number 53154.

[0083] During the process of processing the stored expression value, the control unit 200 can parse out the 5 stored expression values by dividing a single number by 10000, 1000, 100, and 10 respectively. For example, dividing 53154 by 10000, the quotient is 5 and the remainder is 3154. Dividing the remainder 3154 by 1000, the quotient is 3 and the remainder is 154. Dividing the remainder 154 by 100, the quotient is 1 and the remainder is 54. Finally, dividing the remainder 54 by 10, the quotient is 5 and the remainder is 4. Through such a process, the control unit 200 can parse the value stored as a single number into the original expression values 5, 3, 1, 5, 4.

[0084] According to an embodiment of the present invention, by storing 5 expression values as a single number, the storage space for storing data can be minimized.

[0085] Figure 5It is a diagram for explaining a method of determining whether to replace an ion filter when the performance of the ion filter based on an embodiment of the present invention deteriorates.

[0086] Referring to Figure 2 and Figure 5 , taking the start to the end of the operation of the vehicle or system as one cycle, the control unit can derive an expression value in each cycle. The control unit can derive a moving value from nine expression values. In Figure 5 , the case where the moving value is the moving median value is described.

[0087] As the vehicle or system continues to operate, the durability of the ion filter may deteriorate. In this embodiment, the expression value is usually expressed by a number from 1 to 3, and the moving median value can be expressed as 2 or 3. The control unit can confirm that the size of any one of the second number of moving median values stored at the first moment (t1) or the latest moving value is less than or equal to a preset threshold value of 4. That is, the control unit can determine that the ion filter exhibits a mode of deteriorating durability. In addition, the control unit can confirm that the change amount of multiple moving median values or the difference between the latest moving median value and the earliest moving median value among the second number of moving median values stored at the first moment (t1) is less than a preset difference value of 1. This embodiment describes the case where the determined value is the earliest moving median value among multiple moving median values. That is, the control unit can determine that the durability degradation mode of the ion filter is a reliable result. The moving median value is usually expressed as 2 after a certain time after the initial operation of the vehicle or system. Therefore, since the control unit confirms the durability degradation mode of the ion filter according to the satisfaction of the first condition and the second condition, it can be determined that the ion filter needs to be replaced.

[0088] The second moment (t2) can indicate after replacing the ion filter. It can be confirmed that the size of any one of the second number of moving median values stored at the second moment (t2) or the latest moving value is greater than the preset threshold value of 4. Therefore, the control unit can determine that there is no need to replace the ion filter.

[0089] Figure 6 It is a diagram for explaining a judgment method for determining whether to replace an ion filter when a component of a fuel cell system according to an embodiment of the present invention fails.

[0090] Referring to Figure 2 and Figure 3 , taking the start and end of the operation of the vehicle or system as one cycle, the control unit can derive an expression value in each cycle. The control unit can derive a moving value from nine expression values. In Figure 6 , the case where the moving value is the moving median value is described.

[0091] When a high-voltage component applied to a fuel cell system fails, the insulation resistance may decrease even if there is no problem with the durability of the ion filter. In this embodiment, multiple expression values and moving intermediate values are usually expressed as numbers of 5, but near the third moment (t3), the expression values and moving intermediate values are expressed as numbers from 2 to 4. That is, at the third moment (t3), a sharp fluctuation in the insulation resistance value may occur. The control unit can confirm that any one of the second number of moving intermediate values stored at the third moment (t3) or the size of the latest moving intermediate value is below a preset threshold of 4. That is, the control unit can determine that the ion filter exhibits a mode of decreased durability. However, the control unit can confirm that the change amount of the multiple moving intermediate values or the difference between the latest moving intermediate value and the earliest moving intermediate value among the second number of moving intermediate values stored at the third moment (t3) is above a preset difference value of 1. That is, the control unit can determine that there is an error in the determination of the mode of decreased durability of the ion filter. After that, the control unit can stop determining the mode of the ion filter for a certain period of time. The control unit can confirm that any one of the second number of moving intermediate values stored at the fourth moment (t4) when the mode determination of the ion filter is performed again or the size of the latest moving intermediate value is greater than the preset threshold of 4. Confirming that the mode of the ion filter is normal at the fourth moment (t4) may mean that the problems of components other than the ion filter are solved between the third moment (t3) and the fourth moment (t4).

[0092] As described above, embodiments of the present invention have been described with reference to the drawings, but it should be understood that those skilled in the art can implement the present invention in other specific ways without changing the technical idea or basic characteristics of the present invention. Therefore, it should be understood that the embodiments described above should be regarded as examples in all aspects and not as limitations of the present invention.

Claims

1. A system for determining whether to replace an ion filter, comprising: a measurement unit that measures the insulation resistance value of a fuel cell stack during the operation of a vehicle or a system; and a control unit that determines whether to replace the ion filter based on the insulation resistance value. The control unit takes the start to the end of the operation of the vehicle or the system as one cycle, and calculates a moving value based on the insulation resistance values measured in multiple cycles. The moving value refers to a moving average value or a moving median value with respect to the average value or the median value of the insulation resistance value. The control unit determines whether to replace the ion filter based on at least one of the magnitude of the moving value or the change rate of the moving value.

2. The system for determining whether to replace an ion filter according to claim 1, wherein: The control unit determines whether a first condition and a second condition are satisfied. The first condition is to determine whether the magnitude of the moving value is below a preset threshold, and the second condition is to determine whether the change rate of the moving value is less than a preset change rate. When both the first condition and the second condition are satisfied, the control unit determines that the ion filter needs to be replaced.

3. The system for determining whether to replace an ion filter according to claim 2, wherein: The control unit determines whether a third condition is satisfied. The third condition is to count the cases where the insulation resistance value measured within one cycle from the start to the end of the operation of the vehicle or the system is within a specific range, and determine whether the total count is greater than a preset count value. When the first condition, the second condition, and the third condition are all satisfied, the control unit determines that the ion filter needs to be replaced.

4. The system for determining whether to replace an ion filter according to claim 3, wherein: When the insulation resistance value measured within one cycle is below a preset quantity, the control unit does not determine whether the third condition is satisfied based on the insulation resistance value measured within the corresponding cycle.

5. The system for determining whether to replace an ion filter according to claim 4, wherein: The control unit determines whether the total count of the cases where the insulation resistance values measured in consecutive multiple cycles are within the specific range is greater than a preset count value.

6. The system for determining whether to replace an ion filter according to claim 1, wherein: The moving value is calculated based on an expression value obtained by encoding the average value or the median value of the insulation resistance value measured within one cycle with a single-digit number.

7. The system for determining whether to replace an ion filter according to claim 6, wherein, Five expression values are converted into a five-digit number and stored, or Ten expression values are converted into a ten-digit number and stored, or Twenty expression values are converted into a twenty-digit number and stored.

8. The system for determining whether to replace an ion filter according to claim 6, wherein: A preset first quantity of expression values is stored. The control unit calculates the moving value based on the stored preset first quantity of expression values. The control unit determines whether to replace the ion filter based on consecutive preset second quantity of moving values. The preset first quantity is a number larger than the preset second quantity.

9. The system for determining whether to replace the ion filter according to claim 8, wherein, the control unit compares the latest movement value among the preset second number of movement values or the average magnitude of the movement values with a preset threshold value to determine whether the first condition is satisfied.

10. The system for determining whether to replace the ion filter according to claim 9, wherein, the control unit compares the difference between the latest movement value among the preset second number of movement values and a determined value based on previous movement values with a preset difference value to determine whether the second condition is satisfied.

11. The system for determining whether to replace the ion filter according to claim 10, wherein, when the difference between the latest movement value and the determined value is greater than the preset difference value, the control unit determines that there is an error in the measurement of the insulation resistance value, and interrupts the process of determining whether to replace the ion filter for a certain period of time.

12. The system for determining whether to replace the ion filter according to claim 9, wherein, the control unit compares the change rate of the preset second number of movement values with a preset change rate to determine whether the second condition is satisfied.

13. The system for determining whether to replace the ion filter according to claim 12, wherein, only when both the first condition and the second condition are satisfied, the control unit determines that the ion filter needs to be replaced.

14. A method for determining whether to replace the ion filter, implemented by a control unit for determining whether to replace the ion filter, the method comprising: a step of calculating an average value or a median value of the insulation resistance values measured from the start to the end of the operation of the vehicle or system as one cycle; a step of deriving a plurality of expression values obtained by encoding the average value or the median value of the insulation resistance values measured in a plurality of cycles with single-digit numbers; a step of calculating movement values for the plurality of expression values; and a step of determining whether to replace the ion filter based on at least one of the magnitudes of at least one of the movement values or the change rate of the movement values, wherein the movement value refers to a moving average value or a moving median value of the average value or the median value of the insulation resistance value.

15. The method for determining whether to replace the ion filter according to claim 14, wherein, the step of determining whether to replace the ion filter includes: determining whether a first condition and a second condition are satisfied, the first condition being determining whether the magnitude of the movement value is less than or equal to a preset threshold value, and the second condition being determining whether the change rate of the movement value is less than a preset change rate, when both the first condition and the second condition are satisfied, determining that the ion filter needs to be replaced.

16. The method for determining whether to replace the ion filter according to claim 15, wherein, the step of determining whether to replace the ion filter includes: determining whether a third condition is satisfied, the third condition being counting the cases where the insulation resistance value measured in one cycle from the start to the end of the operation of the vehicle or system is within a specific range, and determining whether the total count is greater than a preset count value. When the first condition, the second condition, and the third condition are all satisfied, it is determined that the ion filter needs to be replaced.

17. The method for determining whether to replace the ion filter according to claim 14, wherein, The step of calculating the moving value includes: The step of calculating the moving value according to a preset first number of expression values; and The step of determining whether to replace the ion filter according to a continuous preset second number of moving values.

18. The method for determining whether to replace the ion filter according to claim 17, wherein, Compare the latest moving value among the preset second number of moving values or the average magnitude of the moving value with a preset threshold value to determine whether the first condition is satisfied.

19. The method for determining whether to replace the ion filter according to claim 18, wherein, Compare the difference between the latest moving value among the preset second number of moving values and a determined value based on previous moving values with a preset difference value or compare the change rate of the preset second number of moving values with a preset change rate to determine whether the second condition is satisfied.

20. A storage medium stores computer-readable instructions, and the instructions are executed by a processor, and the processor executes: An operation of calculating an average value or a median value of insulation resistance values measured from the start to the end of the operation of a vehicle or a system as one cycle; An operation of deriving a plurality of expression values obtained by encoding the average value or the median value of the insulation resistance values measured in a plurality of cycles with a single-digit number; An operation of calculating a moving value for the plurality of expression values; And An operation of determining whether to replace the ion filter according to at least one of the magnitudes of at least one of the moving values or the change rate of the moving values, wherein the moving value refers to a moving average value or a moving median value of the average value or the median value of the insulation resistance values.

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