JP5074104B2 - Data storage device - Google Patents

Description

  The present invention relates to a data storage device for storing measurement data, and more particularly to a data storage device using a NAND flash memory as a storage medium.

  There is a solar power generation system that generates DC power using a solar battery, converts DC power into AC power using a power conditioner, and connects the power to a commercial power system to supply the power. In order to manage the power generation status in this solar power generation system, power generation data indicating the operation status of the power conditioner is measured. In addition, weather data such as solar radiation is also measured to analyze the relationship between weather conditions and power generation efficiency. These measurement data are transmitted to a management computer every predetermined time (for example, every minute), accumulated, and used for analyzing the relationship between the weather condition and the power generation efficiency. In the event that trouble occurs in transmission of this measurement data (for example, measurement data could not be received due to an unstable operation of the management computer), the data storage device of the photovoltaic power generation system has a predetermined period. It is necessary to save measurement data (for example, for 3 months). For this reason, the data storage device of the photovoltaic power generation system requires a storage capacity that can store a large amount of data.

  For example, 20 power conditioners are connected to a photovoltaic power generation system, and each storage capacity necessary for storing power generation data input from each power conditioner is 14 bytes, and weather data is stored. If the required storage capacity is 32 bytes, the storage capacity of 20 × 14 + 32 = 312 bytes per minute, 312 bytes × 60 minutes × 24 hours × 30 days × March≈40 MB is required for 3 months.

  It is also necessary to prevent the stored data from being lost due to a power failure. Although there is a method of providing a battery as an auxiliary power source, maintenance is required, and the maintenance cost increases. In order to eliminate the need for maintenance, it is preferable to use a non-volatile memory such as a flash memory in which stored data is not lost even if power is not supplied, instead of enabling power to be supplied in the event of a power failure.

  The flash memory includes a NOR flash memory and a NAND flash memory. The NOR type flash memory can perform random access in units of 1 byte, but is not suitable for increasing the capacity and the writing speed is slow. When a NOR flash memory is used in the data storage device of the above-described photovoltaic power generation system, 20 2 MB NOR flash memories are required to secure a storage capacity of 40 MB. If 20 NOR-type flash memories are installed, the data storage device is undesirably increased in size and weight. Also, it is not realistic in terms of cost.

  On the other hand, the NAND flash memory can be increased in capacity and has a high writing speed. Therefore, the NAND flash memory is more suitable for a data storage device that requires a large storage capacity. However, the number of rewritable times in each storage area of a general NAND flash memory is about 100,000 times. When data is saved in a file format such as FAT, the memory management area is rewritten every time the data is rewritten. Accordingly, the number of times that the NAND flash memory can be rewritten is about 100,000 times. Therefore, when a NAND flash memory is mounted on a data storage device, it is desirable to reduce the number of data rewrites as much as possible, and a method for reducing the number of data rewrites has been developed.

  For example, Japanese Translation of PCT International Publication No. 2005-524156 describes a method of using a NAND flash memory to store measurement data. According to the method described in this publication, the newly acquired data is compared with the data stored in the NAND flash memory and is rewritten only when a change is necessary. Thereby, the number of times of rewriting of the NAND flash memory is reduced.

JP 2005-524156 A

However, when it is necessary to rewrite data every time data is newly acquired, the effect of reducing the number of rewrites by the method described in the above publication does not work. For example, in the case of the data storage device of the solar power generation system, new data is acquired every minute. If a power failure occurs between data acquisition and storage in memory, the acquired data will be lost, so it is desirable to store the acquired data each time. Therefore, data is rewritten every minute, and the management area of the memory is rewritten every minute. Then, the number of rewrites of the management area of the memory exceeds the guaranteed number of times in 100,000 times ÷ (60 minutes × 24 hours) ≈70 days. That is, it is impossible to guarantee a practical period of the lifetime of the NAND flash memory.

  The present invention has been conceived under the circumstances described above, and provides a data storage device capable of preventing data rewriting from being concentrated on a part of a memory used and guaranteeing a practical life of the memory. Its purpose is to do.

  In order to solve the above problems, the present invention takes the following technical means.

Data storage device to a first aspect of the present invention is divided into a plurality of storage areas, address to each storage area to be stored in the first storage means are assigned sequentially, the data The storage area address of the first storage means is stored, a volatile second storage means different from the first storage means, a time measuring means for measuring the current time, and data saving are instructed. Storage control means for storing the data together with time data at the time of storage timed by the time measuring means in the storage area of the address stored in the second storage means of the first storage means; the next each time the data in the first storage means is stored, said the address stored in the second storage means, so that said first plurality of address attached to the storage means is circulated Change the address to A change means, and determination means for determining whether said second of said address stored in the storage unit is lost, when it is judged the address has disappeared by the determination means, the first Using the time data stored in each storage area of one storage means and the time data at the time of determination determined by the time measuring means, the first storage means for data commanded to be stored after the determination Address storage control means for determining the address of the storage area and storing the address in the second storage means (claim 1).

  According to this configuration, the second storage unit stores an address that designates a storage area in which data is to be stored in the first storage unit. When the data is stored in the storage area of the specified first storage means, this address specifies the next storage area if there is a next storage area, and the first storage area if there is no next storage area Is updated to the address you want. Since there is no memory management area in the first storage means that is rewritten each time data is stored, it is possible to prevent data rewriting from being concentrated in some storage areas in the first storage means. In addition, since data is stored in the order of addresses, the rewrite of each storage area is made uniform, and the number of data rewrites for each storage area is reduced. Therefore, even if data rewriting is necessary frequently, rewriting does not concentrate on the same storage area, and deterioration due to rewriting is suppressed, so that the practical life of the first storage means can be guaranteed.

Further, according to this configuration, the time data is stored in association with the data in the first storage means. When the address stored in the second storage means disappears, the address specifying the storage area where the data is to be stored next is determined from the time data stored in each storage area and the current time. Even when the storage of the second storage means disappears due to a power failure or the like, it is possible to prevent the storage area in which data is stored from being unknown when the storage is resumed.

The data storage device according to claim 1 , wherein the address storage control unit is configured to perform the determination time measured by the time data stored in the first storage area of the first storage unit and the time measuring unit. Temporary address setting means for setting a temporary address from the difference between the time data, and whether the data is stored in the temporary address storage area set by the temporary address setting means, or the leading storage area Is stored in the first storage area in the storage area of the address immediately before the temporary address, in which case the time data indicating the storage time before the storage time of the data stored in is stored. First determination means for determining whether or not a first condition that time data indicating a storage time later than the storage time of the data stored is stored is satisfied, When it is determined that the first condition is satisfied by the first determination means, the first determination means stores the temporary address in the second storage means, and the first determination means determines the first If it is determined that the condition is not satisfied, the data is not stored in the temporary address storage area, or the storage time of the data stored in the first storage area in the temporary address storage area A second condition that time data indicating a previous storage time is stored, and a storage after the storage time of the data stored in the first storage area in the temporary address storage area It is determined by the second determination unit that determines which of the third conditions that the time data indicating the time is stored is satisfied, and the second determination unit satisfies the second condition And the first The temporary address in the processing of the determination means is changed to a predetermined address between the temporary address and the address of the head storage area, and the second determination means determines that the third condition is satisfied. And a temporary address changing means for changing the temporary address in the processing of the first determining means to an address next to the temporary address; and the storage processing means sends the temporary address to the second storage means. until memory, said first determination means, and repeat control means for repeating the processing by the second discriminating means and said temporary address change means may consist of (claim 2).

  According to this configuration, even if the storage of the second storage unit is lost due to a power failure or the like, the next data is stored immediately by searching the storage area of the first storage unit using the time data. An address specifying a storage area to be performed can be determined.

In the data storage device according to claim 1 or 2 , the first storage means may be a non-volatile memory (claim 3 ).

  According to this configuration, the data stored in the first storage means is not lost due to a power supply stop such as a power failure, so there is no need to provide an auxiliary power source in the data storage device.

Further, in the data storage device according to claim 3 , the first storage means may be a NAND flash memory (claim 4 ).

  According to this configuration, since the NAND flash memory is suitable for increasing the capacity, the storage capacity of the data storage device can be increased without increasing the size and cost.

The data storage device according to any one of claims 1 to 4 , wherein the plurality of data stored in each storage area of the first storage unit are periodically measured in a solar power generation system. may is data about data and weather for controlling the operation (claim 5).

  According to this configuration, the data for controlling the operation of the system and the data related to the weather, which are periodically measured, are frequently rewritten, but the practical life of the first storage means is also guaranteed by this rewriting. be able to.

The program provided by the second aspect of the present invention stores the data of the nonvolatile first storage device in which the computer is divided into a plurality of storage areas, and addresses are assigned to the storage areas in order. an address to a said first second address storage control means Ru stored in the storage devices of different volatile storage device, each time the storage of the data is commanded, measured by the time measuring device the data together with time data at the time of saving to be, said first storage device, said second data storage control means to the storage area of the stored address Ru is memorize in the memory device, the said first storage device each data Ru stored, the second of said address stored in the storage device, and an address changing means for changing to the next address as said first plurality of address attached to the storage device circulates , Determining means for determining whether or not the address stored in the second storage device is lost; and when the determination means determines that the address is lost, the first storage device Using the time data stored in each storage area and the time data at the time of determination determined by the time measuring device, the address of the storage area of the first storage device for the data to be stored after the determination It determines, characterized in that to function as the second address storage control means for storing the address in the second storage device (claim 6). According to this structure, there exists an effect similar to invention of the said Claim 1.

The program according to claim 6 , wherein the second address storage control unit is configured to measure the time data stored in the first storage area of the first storage device and the time measured by the timing device. Temporary address setting means for setting a temporary address from the difference in time data, and whether the data is stored in the temporary address storage area set by the temporary address setting means, or the first storage In the case where time data indicating a storage time before the storage time of the data stored in the area is stored, the storage area of the address immediately before the temporary address is stored in the first storage area. First determination means for determining whether or not a first condition that time data indicating a storage time later than the storage time of the stored data is stored is satisfied. When it is determined by the first determination means that the first condition is satisfied, a storage processing means for storing the temporary address in the second storage means, and the first determination means by the first determination means If it is determined that the condition is not satisfied, the data is not stored in the temporary address storage area, or the storage time of the data stored in the first storage area in the temporary address storage area A second condition that time data indicating a previous storage time is stored, and a storage after the storage time of the data stored in the first storage area in the temporary address storage area It is determined by the second determination unit that determines which of the third conditions that the time data indicating the time is stored is satisfied, and the second determination unit satisfies the second condition And the above The temporary address in the processing of the determining means is changed to a predetermined address between the temporary address and the address of the first storage area, and the second determining means determines that the third condition is satisfied. Then, a temporary address changing unit that changes the temporary address in the process of the first determining unit to an address next to the temporary address, and the storage processing unit converts the temporary address to the second storage unit. And repeating control means for repeating the processing by the first determining means, the second determining means and the temporary address changing means until the information is stored in the computer, the computer is connected to the temporary address setting means, discriminating means, the storage processing unit, the second determining means, may function as the temporary address change means and repetition control means (claim 7). According to this structure, there exists an effect similar to invention of the said Claim 2 .

The recording medium provided by the third aspect of the present invention is a computer-readable recording medium in which the program according to claim 6 or 7 is recorded (claim 8 ).

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  Hereinafter, a case where a preferred embodiment of the present invention is applied as a data storage device of a solar power generation system will be specifically described with reference to the drawings.

FIG. 1 is a block diagram showing an internal configuration of a data storage device of a photovoltaic power generation system. As shown in FIG. 1, the photovoltaic power generation system includes a plurality of power conditioners 20, meteorological data measuring devices 40 to 44, and a data storage device that stores power generation data and weather data indicating the operation status of the power conditioner 20. 1. It is composed of a management computer 5 for analyzing the operational status of the photovoltaic power generation system and the relationship between weather and power generation efficiency, and a system and a solar cell (not shown). The power output terminal of each power conditioner 20 is connected in parallel to the power input terminal of the system. The output terminals of the measured values of the voltage / current of each power conditioner 20 and the output terminals of the measuring devices 40 to 44 are connected to the data storage device 1. A management computer 5 is connected to the data storage device 1.

Data storage device 1 collects the power data and weather data stored, and transmits the data according to an instruction from an external management computer 5 to the management computer 5. The data storage device 1 includes a CPU 11, a ROM 12, a RAM 13, a NAND flash memory 14, a power conditioner input / output I / F 15, a measurement device input / output I / F 16, an input / output I / F 17, and a timer 18. Are connected to each other by a bus (BUS) 19.

  Twenty power conditioners 20 are connected to the power conditioner input / output I / F 15. The measurement device input / output I / F 16 includes a plurality of types of measurement devices (in this embodiment, five types of measurement devices) for measuring meteorological data, that is, a pyranometer 40, a thermometer 41, an anemometer 42, An anemometer 43 and a rain gauge 44 are connected. An external management computer 5 is connected to the input / output I / F 17 via a communication line.

  The data storage device 1 transmits measurement data calculated for each measurement item from each measurement value input from each power conditioner 20 and each measurement device 40 to 44 to the management computer 5, and the NAND flash memory 14. To remember. Each measurement value is input in response to a measurement instruction every 6 seconds from the CPU 11, and an average value is calculated every time 10 measurement values are input. Therefore, each measurement data is calculated every minute. . In addition, the input of the measurement value of each measurement item and the calculation of measurement data are performed at the same timing. The measurement data calculated for each measurement item is collectively stored in one sector of the NAND flash memory 14 together with a time stamp which is data indicating the stored time. Note that the time from the measurement instruction by the CPU 11 to the input of the measurement value is a very short time, and the calculation of the measurement data by the CPU 11 is also a very short time. Therefore, the time when the measurement data indicated by the time stamp is stored can be considered to be the same as the time when the tenth measurement value is measured.

In addition, from each power conditioner 20, the current value and voltage value of the direct-current power which the connected solar cell generated as a measured value, the current value and voltage value of the alternating current power converted by the said power conditioner 20 are measured. Is entered. The calculated measurement data is stored as power generation data. In this embodiment, since 20 power conditioners 20 are provided, the power generation data calculated every minute is 80 pieces of measurement data. The solar radiation meter 40, the air temperature meter 41, the wind vane meter 42, the anemometer 43, and the rain gauge 44 are respectively input with the solar radiation amount, the temperature, the wind direction, the wind speed, and the rain amount. Data, wind direction data, wind speed data, and rainfall data are stored as weather data.

  The CPU 11 is the center of control of the data storage device 1 and performs control according to a control program stored in the ROM 12. Specifically, the CPU 11 issues a measurement instruction to each power conditioner 20 via the power conditioner input / output I / F 15 every 6 seconds according to the time counted by the timer 18, and via the measurement device input / output I / F 16. Then, a measurement instruction is issued to each measurement device 40-44. Further, the CPU 11 calculates an average value of the input measurement values as measurement data. Further, the CPU 11 transmits the calculated measurement data to the management computer 5 and stores it in the NAND flash memory 14. Further, the CPU 11 transmits the stored measurement data to the management computer 5 based on a request from the management computer 5.

  The ROM 12 stores a control program for controlling the data storage device 1.

  The NAND flash memory 14 is for storing measurement data calculated by the CPU 11. The NAND flash memory 14 does not employ a file format in which the management area is rewritten each time data is rewritten, divides all memory areas into sectors, and stores measurement data based on addresses stored in the RAM 13. The method of memorizing is adopted. This storage method will be described later.

  The RAM 13 provides a work area for the CPU 11 and temporarily stores calculation data and the like. In addition, the RAM 13 stores an address (hereinafter referred to as “save destination sector address”) of a sector (hereinafter referred to as “save destination sector”) in the NAND flash memory 14 where measurement data is stored next. ing.

  The power conditioner input / output I / F 15 serves as an interface with each power conditioner 20. Each power conditioner 20 converts the DC power generated by the solar cell into AC power and connects it to the commercial power system to supply power, and is connected in parallel to the commercial power system. When each power conditioner 20 receives a measurement instruction from the CPU 11, it measures the current value and voltage value of the DC power generated by the solar cell and the current value and voltage value of the converted AC power according to the measurement instruction. The measurement value is returned to the CPU 11. Although this embodiment demonstrated the case where 20 power conditioners 20 were connected, it is not restricted to this, What is necessary is just to connect one or more arbitrary numbers.

  The measuring device input / output I / F 16 serves as an interface with each measuring device 40-44. When receiving a measurement instruction from the CPU 11, the solar radiation meter 40, the air temperature meter 41, the anemometer 42, the anemometer 43, and the rain gauge 44 measure the solar radiation amount, the temperature, the wind direction, the wind speed, and the rainfall according to the measurement instructions. The measurement value is returned to the CPU 11. The measuring device connected to the measuring device input / output I / F 16 is not limited to the above, and a measuring device for measuring data required for analyzing the power generation efficiency of solar power generation is connected.

  The input / output I / F 17 serves as an interface with the external management computer 5. When calculating the measurement data, the CPU 11 transmits the calculated measurement data to the management computer 5. The management computer 5 monitors the operating status of the photovoltaic power generation system based on the received measurement data, and analyzes the relationship between the power generation amount and the weather conditions using the accumulated measurement data. In addition, when data loss occurs in the accumulated measurement data, the management computer 5 makes a request to the data storage device 1 to transmit the data loss, and is stored in the NAND flash memory 14. Send the measured data.

The timer 18 measures the time when the measurement value is measured. The timer 18 is a so-called RTC (Real Time Clock) and measures the current time, and the time to be measured includes date information. The CPU 11 issues a measurement instruction every 6 seconds according to the time measured by the timer 18. Further, the time when the measurement data is stored which is measured by the timer 18 is stored in the NAND flash memory 14 together with the measurement data as a time stamp.

  Hereinafter, the data structure and storage method of each sector of the NAND flash memory 14 according to the present embodiment will be described.

  FIG. 2 is a diagram for explaining the data structure of each sector of the NAND flash memory 14. FIG. 3 is a diagram illustrating an example of data stored in the NAND flash memory 14.

  As shown in FIG. 2, each sector includes an address area 101, a measurement data area 102, a time stamp area 103, and a data flag area 104. One sector has a 512-byte storage area, and the NAND flash memory 14 is rewritten in units of sectors.

  The address area 101 stores an address for specifying a sector. In this embodiment, the address of the first sector is “0”, and the addresses of the following sectors are incremented by “1” (see FIG. 3).

  In the measurement data area 102, the power generation data calculated by the CPU 11 from the measurement values input from the power conditioners 20 and the weather data calculated by the CPU 11 from the measurement values input from the measurement devices 40 to 44 are measured data. Remembered.

  Since the power generation data of each power conditioner 20 consists of 14 bytes and the meteorological data consists of 32 bytes, a total of 20 × 14 + 32 = 312 bytes is allocated as a measurement data area.

  The time stamp area 103 stores a time stamp that is data indicating the time when the measurement data is stored. As this time, the date, time, and minute measured by the timer 18 are used (see FIG. 3). As described above, the time when the measurement data indicated by the time stamp is stored indicates the time when the last measurement value among the measurement values for calculating the measurement data is measured.

  The data flag area 104 stores information indicating whether or not measurement data is stored in the sector. When the measurement data is not stored in the sector, “0” is stored, and when the measurement data is stored in the sector, it is rewritten to “1” (see FIG. 3).

  The storage area of the NAND flash memory 14 is divided into 512-byte sectors. For example, since the storage capacity of the NAND flash memory 14 of this embodiment is 70 MB, it includes 70000000 ÷ 512≈136718 sectors. The order of each sector is determined by the address.

  In the present embodiment, the measurement data is stored in the NAND flash memory 14 in a ring format. That is, measurement data is stored in each sector in the order of addresses, and when measurement data is stored in the sector at the last address, the measurement data is stored in the sector at the top address next.

FIG. 4 is a diagram for explaining a format in which measurement data is stored in the NAND flash memory 14. For simplicity, the case where the number of sectors is 10 is described. The measurement data measured at time 12:00 is stored in the sector at address 0 . Each time it is measured in total, measurement data to each sector in order of address is stored. Middle, meter if none was measured measurement data for that time is not stored, in (Fig. 4 following measured measurement data are stored, time 12: 04-12: The 06 was not measured total Therefore, the measurement data at time 12:07 is stored in the sector at address 4). When the measurement data at time 12:12 is stored in the sector at address 9, the next measurement data at time 12:13 is stored in the sector at address 0 at the head.

  With this ring-type storage method, rewriting of data in the NAND flash memory 14 is always performed on the oldest measurement data. Therefore, the NAND flash memory 14 stores the number of measurement data corresponding to the number of sectors from the old measurement data to the latest measurement data in order. For example, in this embodiment, since the number of sectors is 136718, measurement data from 136718 minutes before (that is, 94 days and 22 hours and 38 minutes before) to the present is stored, and measurement for three months is performed. Data can be stored.

  For example, in FIG. 3, from the measurement data stored at 6:03 on January 27, 2007 in the sector of address 1002, the measurement stored at 4:41 on May 2, 2007 in the sector of address 1001. Up to about 3 months of measurement data is stored.

  In addition, in order to save the trouble of searching for a storage destination sector every time data is saved every minute, and to avoid the problem that data cannot be saved due to the time required for the search, this embodiment In the RAM 13, the storage destination sector address (the address of the sector where measurement data is stored next) is stored. When the measurement data is stored in the storage destination sector in the NAND flash memory 14, the storage destination sector address is updated to the address of the next sector. The storage sector address is updated to the address of the head sector when the measurement data is stored in the last sector. Thus, when the measurement data is stored in the last sector, the measurement data is stored in the next sector.

Since the storage sector address is stored in the RAM 13, it is not necessary to provide a memory management area in the NAND flash memory 14. Therefore, rewriting to the management area does not concentrate like the file format. Therefore, when the NAND flash memory 14 is guaranteed to be rewritten 100,000 times, the measurement data is rewritten every three months in each storage area, so that the rewrite life of 25000 years (= 100,000 / 4) is guaranteed in the calculation. Is done.

  Since the storage destination sector address is stored in the RAM 13, the storage destination sector address disappears from the RAM 13 when power supply is stopped such as during a power failure. Therefore, when the power supply is resumed and the storage of the measurement data is resumed, the sector in which the measurement data is stored becomes unknown. In order to avoid this, it is necessary to find a sector in which data is most recently saved and to set the next sector as a save destination sector address as soon as power supply is resumed.

  In the present embodiment, the storage destination sector address at the time of power resupply or reset is searched from the time stamp stored in the head sector and the current time. Hereinafter, the processing procedure of the search for the storage destination sector address will be described with reference to the flowchart shown in FIG. 6 and FIG.

FIG. 5 is an example of data stored in the NAND flash memory 14 for explaining the processing procedure of the storage destination sector address search. For simplification, the time and date elements of the time stamp area 103 are omitted, and only the hour and minute elements are described in a time format such as 12:00. FIG. 5 (a) shows a case where measurement data is stored in the NAND flash memory 14 in an unstored state from time 12:00 and a time stamp of 13:41 and measurement data are stored in the sector of address 101. Data storage is suspended. Accordingly, the measurement data and the time stamp are not stored in the sector after the address 102. FIG. 5B shows a state in which the storage of measurement data has been continued for three months or more, and the storage of the measurement data is interrupted when the time stamp of 13:41 and the measurement data are stored in the address 101. Therefore, the measurement data and the time stamp stored about three months ago are stored in the sector after the address 102.

  FIG. 6 is a flowchart showing the processing procedure of the storage destination sector address search.

  This process is performed when the power supply is resumed after the power supply is stopped, such as during a power failure, and searches for the storage destination sector address (address 102 in the state of FIG. 5) that has disappeared from the RAM 13. is there.

First, the current time is converted to an absolute time Tp (S1). Here, the absolute time represents an elapsed time from an arbitrarily set reference time to the current time in minutes, and is used to simplify the process of comparing the times. For example, if 0:00 am on January 1, 2007 is the base time and the current time is 4:10 pm on May 1, 2007, then from 0:00 am on January 1, 2007 to May 2007 elapsed time up to 10 minutes 1:00 pm 4, because it is +10 minutes 31 + 28 + 31 + 30 + 16 hours, converting it to minutes, 173,770 and (= (31 + 28 + 31 + 30) × 24 + 16) × 60 + 10) Become. Note that the reference time is arbitrarily set, and may be, for example, 0:00 on January 1 of the year to which the data storage device 1 is installed or manufactured.

  Next, it is determined whether or not there is measurement data in the head sector (S2). That is, the information in the data flag area 104 of the sector with the address “0” is read out, and it is determined whether it is “0” or “1”. The same is true for determining whether there is measurement data in the following processing. When it is determined that there is no measurement data in the first sector (that is, when the information read from the data flag area 104 is “0”) (S2: NO), the measurement data is still input to the NAND flash memory 14. Since it has not been performed, “0” is stored in the RAM 13 as the storage destination sector address (S3), and the process is terminated. This is a state in which power is input for the first time after the data storage device 1 is installed, or immediately after all the storage in the NAND flash memory 14 is erased and reset.

  When it is determined that there is measurement data in the first sector (that is, when the information read from the data flag area 104 is “1”) (S2: YES), the time stamp of the first sector is read and absolute Time Ta is converted (S4). That is, the time stamp information is read from the time stamp area 103 of the sector with the address “0” and converted to the absolute time Ta.

  Next, X (= Tp−Ta) is calculated as the difference between Tp and Ta (S5), and it is determined whether or not X is larger than the total number of sectors Xt (for example, 136718 in this embodiment) (S6). ). When X is larger than Xt (S6: YES), Xt is subtracted from X (S7), and the process returns to step S6. If X is less than or equal to Xt (S6: NO), the process proceeds to step S8.

X indicates the elapsed time from the time indicated by the time stamp of the first sector to the current time in minutes. Here, the address of the head sector is “0”, and measurement data is stored in each sector in order every one minute, and the address is incremented by one. Therefore, if measurement data storage continues continuously without interruption, X is the address of the sector where the measurement data at the current time is to be stored. However, since the storage of the measurement data has been interrupted, it is not appropriate to set X as the address of the sector where the measurement data is stored when the measurement data storage is resumed. Because, when measurement data storage is resumed from the sector at address X, does the measurement data stored in the previous measurement data (measurement data about three months ago) remain in the sector corresponding to the measurement data storage interruption period? This is because a sector in which measurement data is not stored continues. In order to prevent this, the measurement data at the time when the measurement data storage is resumed needs to be stored in the sector next to the sector in which the measurement data is stored before the measurement data storage is interrupted.

  For example, in the state shown in FIG. 5A, when measurement data storage is resumed at 13:44, X becomes 104 (elapsed fraction from 12:00 to 13:44). The address of the sector to be stored should be 102, and this address search is performed in step S8 and subsequent steps.

  If the measurement data storage has been interrupted for three months or more, X calculated as the difference between Tp and Ta exceeds the maximum value of the sector address of the NAND flash memory 14. Therefore, in this case, in steps S6 and S7, X is made an address within the range by subtracting the total number of sectors Xt from X.

  From step S8, the storage destination sector address is searched using X calculated in steps S1 to S7 as a temporary address. That is, when the address X is larger than the storage destination sector address (the addresses 103 and higher in FIGS. 5A and 5B), the address X is changed so as to be equal to or lower than the storage destination sector address. When the address X is smaller than the storage destination sector address (101 or less), the address X is incremented by one. These processes are repeated until the address X matches the storage destination sector address. Note that there are sectors in which measurement data is not stored for three months after the data storage device 1 is activated for the first time (see FIG. 5A). In this case, since the data of the sector at the address X may not be read, the processing is performed separately. Specific processing will be described below.

  First, it is determined whether or not there is measurement data in the sector at address X (S8). If there is no measurement data in the sector at address X (S8: NO), it is determined whether or not there is measurement data in the sector at address (X-1) (S9). When there is measurement data in the sector at the address (X-1) (S9: YES), the address X is stored in the RAM 13 as a storage destination sector address (S10), and the process is terminated.

  That is, when measurement data is not stored in the sector at address X and measurement data is stored in the sector at the previous address (X-1) (in FIG. 5A, address X is address 102). The address X is stored in the RAM 13 since the sector at the address X is the sector where the measurement data is to be stored next.

If there is no measurement data in the sector at address (X-1) (S9: NO), an address between “0” and X is set as address X (S11), and the process returns to step 8. That is, when the measurement data is not stored in the sector at the address X and the measurement data is not stored in the sector at the previous address (X-1) (in FIG. 5A, the address X is the address). If the address X is equal to or greater than 103, the address X is set to an intermediate address between “0” and X in order to make the address X equal to or lower than the storage destination sector address. Steps S8, S9, and S11 are repeated until the address X becomes equal to or less than the storage destination sector address. The intermediate address between “0” and X is a value obtained by dividing by 2 when X is an even number, and a value obtained by dividing (X−1) by 2 when X is an odd number. For example, in FIG. 5A, when the address X is 335, the address X is 167 (= 334/2). However, since it is still 103 or more, the intermediate address is calculated again to 84 (= (167-1) / 2).

  If there is measurement data in step S8 (S8: YES), the time stamp of the sector at address X is read and converted to absolute time T (S12). It is determined whether or not the absolute time T is smaller than the absolute time Ta of the time stamp of the first sector (S13). That is, it is determined whether or not the measurement data stored in the sector at the address X is older than the measurement data stored in the head sector.

  If T is smaller than Ta (S13: YES), the time stamp of the sector at the address (X-1) is read and converted to the absolute time T '(S14). It is determined whether or not the absolute time T 'is equal to or greater than Ta (S15). If T 'is equal to or greater than Ta (S15: YES), the address X is stored in the RAM 13 as the storage destination sector address (S16), and the process is terminated.

  That is, the measurement data stored in the sector at the address X is older than the measurement data stored in the head sector, and the measurement data stored in the sector at the previous address (X-1) is stored in the head sector. If the measured data is newer (in the case of FIG. 5B, the address X is the address 102), the address X is stored in the RAM 13 because the sector of the address X is the sector where the measured data is to be stored next. The

  If T ′ is smaller than Ta in step S15 (S15: NO), the process proceeds to step S11. That is, the measurement data stored in the sector is older than the measurement data stored in the head sector, and the measurement data stored in the sector at the previous address (X-1) is also stored in the head sector. If it is older than the measured data (in FIG. 5B, the address X is equal to or greater than the address 103), an address between “0” and X is set to the address X in order to make the address X equal to or less than the storage destination sector address To do. Steps S8, S12 to S15, and S11 are repeated until the address X becomes equal to or less than the storage destination sector address.

  If T is greater than or equal to Ta in step S13 (S13: NO), the address X is incremented by 1 (S17). That is, since the address X is smaller than the storage destination address (the addresses X are addresses 0 to 101 in FIGS. 5A and 5B), the address X is set to the next address.

  It is determined whether or not there is measurement data in the sector at address X (S18). If there is no measurement data (S18: NO), the process proceeds to step S16. If there is measurement data (S18: YES), the time stamp of the sector at address X is read and converted to absolute time T (S19). It is determined whether or not the absolute time T is smaller than Ta (S20). When T is smaller than Ta (S20: YES), the process proceeds to step S16, and when T is equal to or greater than Ta (S20: NO), the process returns to step S17.

  That is, the measurement data does not exist in the sector of address X (in FIG. 5A, address X becomes address 102), or the measurement data stored in the sector of address X is stored in the head sector. The address X is incremented by 1 until it becomes older than the measurement data (in FIG. 5B, the address X becomes the address 102). If no measurement data exists in the sector at address X, or if the measurement data stored in the sector at address X is older than the measurement data stored in the first sector, the measurement data is stored next in the sector at address X. Since this is a sector to be used, the address X is stored in the RAM 13 in step S16.

The search for the storage destination sector address is not limited to the above method, and may be performed by another method. For example, in the flowchart of FIG. 6 described above, when Step S13 is NO, Steps S17 to S20 may not be repeated, but after Step S17, the process may return to Step S8. If the processing speed of the CPU 11 is fast and the search process does not take time, the search may be performed in order from the first sector.

  Next, referring to the flowcharts shown in FIGS. 8 and 9 and FIG. 7 for the process of reading the requested measurement data from the NAND flash memory 14 in order to transmit the measurement data requested from the management computer 5. To explain. The management computer 5 designates the measurement time of the first measurement data (hereinafter referred to as “designated time”) and the measurement time of the last measurement data among the requested measurement data, and transmits a transmission request. When the CPU 11 receives the measurement data transmission request, the CPU 11 reads the measurement data corresponding to the period from the designated time to the measurement time of the last measurement data (hereinafter referred to as “designated period”) from the NAND flash memory 14, and the RAM 13. Then, it is transmitted to the management computer 5 via the input / output I / F 17. In addition, when 3 months or more ago is designated as the designated time, the CPU 11 transmits that there is no measurement data.

FIG. 7 is an example of data stored in the NAND flash memory 14 for explaining the processing procedure for reading measurement data. As in FIG. 5, only the hour and minute elements are described in the time format for the time stamp in the time stamp area 103 . Although not shown, 10:20 measurement data is stored at address 0, and then the measurement data is stored, and a situation in which measurement data of 12: 0 to 12:03 is requested from the management computer 5 is taken as an example. . In FIGS. 7D and 7E, measurement data of 11:56 to 12:04 is not stored. Further, measurement data after 12:02 is not stored in FIG. 7F, and measurement data after 12:01 is not stored in FIG. 7G. In FIG. 7H, the measurement data from 11:55 is stored again in the sector after address 101, and in FIG. 7I, the measurement data from 12:01 to 12:02 is stored. Absent.

  8 and 9 are flowcharts showing the measurement data reading processing procedure.

  The designated time is converted to absolute time Tr (S31), and the time stamp of the first sector is read and converted to absolute time Ta (S32). Note that when there is no data in the head sector, it is impossible to read data, so empty data for a specified period is input to the transmission buffer, and the measurement data reading process is terminated.

  Next, X (= Tr−Ta) is calculated as the difference between Tr and Ta (S33). When the measurement data is stored in order from the first sector without interruption, X is the address of the sector that stores the measurement data at the specified time. For example, in FIG. 7A, X is 100 (elapsed minutes from 10:20 to 12:00), and measurement data of 12:00 is stored in the sector of address 100.

  However, when measurement data is not stored due to a power failure during the process, or when the timer 18 is adjusted, X does not become the address of the sector where the measurement data at the specified time is stored. Accordingly, in steps S34 to S44, a search for a sector in which measurement data at a specified time is stored is performed using X as a temporary address.

  First, it is determined whether or not measurement data exists in the sector at address X (S34). When there is no measurement data (S34: NO), the address X is decremented by 1 (S35), and the process returns to step S34. That is, the address is decreased to the sector where the measurement data is stored. For example, in FIG. 7F, since no data is stored in the sector at address X (= 100), X is decreased by 1 to 99, and the search is performed again.

  If there is data in step S34 (S34: YES), the time stamp of the sector at address X is read and converted to absolute time T (S36). This absolute time T is compared with the absolute time Tr of the designated time (S37).

  If T = Tr in step S37, that is, if the time stamp of the sector at address X matches the specified time, the sector at address X is the sector in which the measurement data at the specified time is stored. Accordingly, the measurement data stored in the sector at the address X is stored in the transmission buffer as measurement data at the designated time (S38), and the process proceeds to step S51. For example, in FIG. 7A, the time stamp of the sector at address X (= 100) is 12:00 and matches the specified time, so the measurement data stored in the sector at address 100 is stored in the transmission buffer. .

  If T> Tr in step S37, that is, if the time stamp of the sector at address X is after the specified time, address X is decremented by 1 (S39), and the process returns to step S34. That is, the search is performed again using the previous address (X-1) as the address X. For example, in FIGS. 7B and 7D, since the time stamp of the sector at the address X (= 100) is after the specified time, X is decreased by 1 to 99, and the search is performed again.

  If T <Tr in step S37, that is, if the time stamp of the sector at address X is before the specified time, it is determined whether or not there is measurement data at address (X + 1) (S40), and there is measurement data. (S40: YES), the time stamp of the sector at the address (X + 1) is read and converted to the absolute time T ′ (S41). It is determined whether or not the absolute time T ′ is less than or equal to the absolute time Tr of the designated time (S42). If T ′ ≦ Tr (S42: YES), the address X is incremented by 1 (S43), and step S34 is performed. Return to.

  That is, when the time stamps of the address X and the next address (X + 1) are both less than or equal to the absolute time Tr of the designated time, the next address (X + 1) is used as the address X to search again. For example, in FIG. 7C, the time stamp of the sector at address X (= 100) is 11:59 before the specified time, and the time stamp of the next address 101 is 12:00 and before the specified time. X is incremented by 1 to 101, and the search is performed again.

  If there is no measurement data in step S40 (S40: NO), and if T ′> Tr in step S42 (S42: NO), the measurement data at the specified time is not stored, so the measurement data at the specified time is empty. The data is stored in the transmission buffer (S44), and the process proceeds to step S51. For example, in FIG. 7E, the time stamp of the sector at address X (= 100) is 11:55 before the specified time, and the time stamp of the next address 101 is 12:05 after the specified time. The empty data is stored in the transmission buffer as the measurement data at the designated time.

  As described above, when the sector in which the measurement data at the designated time is stored is searched and the measurement data at the designated time or the empty data is stored in the transmission buffer, the following processing is performed for the designated period. Read the measurement data in

  First, as the next time within the specified period (hereinafter referred to as “search time”), Tr is incremented by 1 (S51), and address X is incremented by 1 (S52). When the measurement data is stored in order without interruption, this X is the address of the sector that stores the measurement data of the search time (see the sector at address 101 in FIG. 7A).

  However, if the search time exceeds the current time, the measurement data is not yet stored in the sector at address X (see the sector at address 101 in FIG. 7 (g)). Further, when the timer 18 is returned for time adjustment in the middle of the period corresponding to the designated period, measurement data at a time before the search time may be stored in the sector of the address X (FIG. 7). (H) See sector at address 101). Similarly, when the timer 18 is advanced or measurement data is not stored due to a power failure or the like, measurement data at a time later than the search time may be stored in the sector of the address X (FIG. 7). (I) See sector at address 101).

  Accordingly, in steps S51 to S63, a search is performed for a sector in which measurement data of the search time is stored using X as a temporary address.

  First, it is determined whether or not all measurement data (including empty data) within a specified period has been stored in the transmission buffer (S53). If all of them are stored (S53: YES), the measurement data reading process is terminated. If not all are stored (S53: NO), it is determined whether or not there is measurement data in the sector of address X (S54).

  When there is no measurement data (S54: NO), empty data is stored in the transmission buffer as measurement data for the remaining specified period (S55), and the measurement data reading process is terminated. For example, in FIG. 7G, after the measurement data of the sector at the address 100 is stored in the transmission buffer as the measurement data at the designated time 12:00, the measurement data is not stored in the sector at the address 101 increased by one. Therefore, empty data is stored in the transmission buffer within the remaining designated period, that is, as measurement data of 12:01, 12:02, and 12:03.

  If there is measurement data (S54: YES), the time stamp of the sector at address X is read and converted to absolute time T (S56). The absolute time T and the absolute time Tr are compared (S57).

  If T = Tr in step S57, that is, if the time stamp of the sector at address X matches the search time, the sector at address X is the sector in which the measurement data for the search time is stored. Therefore, the measurement data stored in the sector at address X is stored in the transmission buffer as measurement data for the search time (S58), Tr is incremented by 1 as the next search time (S59), and address X is incremented by 1. (S60), the process returns to step 53. For example, in FIG. 7A, after the measurement data of the sector at the address 100 is stored in the transmission buffer as the measurement data at the designated time 12:00, the time stamp of the sector at the address 101 increased by 1 is 12:01. It matches the search time 12:01. Therefore, the measurement data of the sector at the address 101 is stored in the transmission buffer as the measurement data at the search time 12:01, the next search time is set to 12:02, the address is set to 102, and the search is performed again.

  If T <Tr in step S57, that is, if the time stamp of the sector at address X is before the specified time, address X is incremented by 1 (S61), and the process returns to step S53. That is, the search is performed again with the next address (X + 1) as the address X. For example, in FIG. 7H, after the measurement data of the sector at the address 100 is stored in the transmission buffer as the measurement data at the designated time 12:00, the time stamp of the sector at the address 101 increased by 1 is 11:55. The search time is before 12:01. Therefore, the address is incremented by 1 to 102, and the search is performed again.

  If T> Tr in step S57, that is, if the time stamp of the sector at the address X is later than the specified time, empty data is stored in the transmission buffer on the assumption that the measurement data of the search time is not stored (S62). Tr is incremented by 1 as the search time (S63), and the process returns to step 53. That is, the measurement data at the next search time is searched. For example, in FIG. 7 (i), after the measurement data of the sector at the address 100 is stored in the transmission buffer as the measurement data at the designated time 12:00, the time stamp of the sector at the address 101 increased by 1 is 12:03. It is after the search time 12:01. Accordingly, empty data is stored in the transmission buffer as measurement data at the search time 12:01, the search time is increased by 1 minute to 12:02, and a search for the next search time is performed.

  Steps S53 to S63 are repeated until all measurement data (including empty data) within the specified period is stored in the transmission buffer (S53: YES) or the search time exceeds the current time (S54: NO). Thus, measurement data within the specified period is accumulated in the transmission buffer. When the measurement data reading process is completed, the measurement data stored in the transmission buffer is transmitted to the management computer 5.

Note that reading of measurement data is not limited to the above method, and other methods may be used. For example, if the processing speed of the CPU 11 is fast and the search process does not take a long time, the measurement data within the specified period is stored in the transmission buffer by referring to the time stamps stored in order from the first sector. May be.

As described above, in the data storage device according to the present embodiment, since the storage destination sector address is stored in the RAM 13 , rewriting to a part of the storage area is not concentrated in the NAND flash memory 14 storing the measurement data. The practical life of the NAND flash memory 14 can be guaranteed. Further, since the time stamp is stored together with the measurement data, when the measurement data is resumed after the storage interruption, it is possible to search for the sector where the measurement data should be stored next by using this time stamp. . Furthermore, when reading measurement data, the necessary measurement data can be read quickly using the time stamp.

  In the above embodiment, the case where the present invention is applied as a data storage device of a photovoltaic power generation system has been described as an example. However, the present invention is not limited thereto, and the present invention is a data storage device that needs to store and rewrite a large amount of data. Can be applied.

It is a block diagram which shows the internal structure of the data storage apparatus at the time of applying the data storage apparatus which concerns on this invention as a data storage apparatus of a photovoltaic power generation system. It is a figure for demonstrating the data structure of each sector of NAND type flash memory. It is a figure which shows the example of the data memorize | stored in NAND flash memory. It is a figure for demonstrating the storage format of a NAND type flash memory. It is an example of the data memorize | stored in the NAND type flash memory for demonstrating the process sequence of a preservation | save destination sector address. It is a flowchart which shows the process sequence of a storage destination sector address search. It is an example of the data memorize | stored in the NAND type flash memory for demonstrating the process sequence of measurement data reading. It is a flowchart which shows the process sequence of measurement data reading. It is a flowchart which shows the process sequence of measurement data reading.

1 Data storage device 11 CPU
12 ROM
13 RAM
14 NAND flash memory 15 Power conditioner I / O I / F
16 Measuring device input / output I / F
17 Input / output I / F
18 Timer 19 BUS
20 Power conditioner 40 to 44 Measuring device 5 Management computer 101 Address area 102 Data area 103 Time stamp area 104 Data flag area

Claims (8)

First storage means that is divided into a plurality of storage areas, and addresses are sequentially assigned to the storage areas ;
Stores the address of the storage area of the to be stored data first storage means, second storage means of different volatility with the first storage means,
A time measuring means for measuring the current time;
Each time data storage is commanded, the data is stored in the storage area of the address stored in the second storage means of the first storage means together with the time data at the time of storage timed by the time measuring means. Storage control means for storing;
Each time the data is stored in the first storage means, the address stored in the second storage means is circulated through a plurality of addresses attached to the first storage means. An address changing means for changing to an address ;
Determining means for determining whether or not the address stored in the second storage means has disappeared;
When it is determined by the determining means that the address is lost, the time data stored in each storage area of the first storage means and the time data at the time of determination timed by the time measuring means are An address storage control means for determining an address of a storage area of the first storage means for data to be stored after the determination, and storing the address in the second storage means;
Data storage apparatus comprising the. The address storage control means includes
Temporary address setting means for setting a temporary address from the difference between the time data stored in the first storage area of the first storage means and the time data at the time of determination measured by the time measuring means;
The time indicating whether the data is not stored in the storage area of the temporary address set by the temporary address setting means or the storage time before the storage time of the data stored in the head storage area Time data indicating a storage time later than the storage time of the data stored in the head storage area in the storage area of the address immediately before the temporary address is stored. First determination means for determining whether or not the first condition of being stored is satisfied;
A storage processing unit for storing the temporary address in the second storage unit when the first determination unit determines that the first condition is satisfied;
If it is determined by the first determination means that the first condition is not satisfied, the data is not stored in the temporary address storage area, or the first address is stored in the temporary address storage area. The second condition that time data indicating a storage time before the storage time of the data stored in the storage area is stored, and the storage area of the temporary address is stored in the top storage area. Second determination means for determining which of the third conditions that time data indicating a storage time later than the storage time of the data is stored is satisfied;
When it is determined by the second determination means that the second condition is satisfied, the temporary address in the processing of the first determination means is determined between the temporary address and the address of the head storage area. If the second determination means determines that the third condition is satisfied, the temporary address in the processing of the first determination means is changed to the next address of the temporary address. Temporary address changing means for
Repetitive control means for repeating the processing by the first determination means, the second determination means and the temporary address change means until the storage processing means stores the temporary address in the second storage means;
The data storage device according to claim 1 , comprising: It said first storage means, characterized in that it is a non-volatile memory, data storage device according to claim 1 or 2. 4. The data storage device according to claim 3 , wherein the first storage means is a NAND flash memory. The plurality of data stored in each storage area of the first storage means are data for controlling the operation of the system periodically measured in a photovoltaic power generation system and data on weather, The data storage device according to any one of claims 1 to 4 . Computer
An address for storing data of the nonvolatile first storage device that is divided into a plurality of storage areas and in which the addresses are assigned in order to each storage area is designated as a volatile first that is different from the first storage device. an address storage control unit Ru is stored in the second storage device,
Each time saving of data is commanded, together with time data during storage which is clocked by the data timing device, said first storage device, the storage area of the address stored in the second storage device a data storage control means to Ru is memorize,
Wherein for each of the data is Ru stored in the first storage device, said second of said address stored in the storage device, said first plurality of address attached to the storage device of the next to circulate An address changing means for changing to an address;
Determining means for determining whether or not the address stored in the second storage device is lost;
If it is determined by the determining means that the address is lost, the time data stored in each storage area of the first storage device and the time data at the time of determination timed by the time measuring device are obtained. A second address storage control means for determining an address of a storage area of the first storage device for data to be stored after the determination, and storing the address in the second storage device;
A program characterized by making it function. The second address storage control means includes:
Temporary address setting means for setting a temporary address from a difference between the time data stored in the first storage area of the first storage device and the time data at the time of determination determined by the time measuring device;
The time indicating whether the data is not stored in the storage area of the temporary address set by the temporary address setting means or the storage time before the storage time of the data stored in the head storage area Time data indicating a storage time later than the storage time of the data stored in the head storage area in the storage area of the address immediately before the temporary address is stored. First determination means for determining whether or not the first condition of being stored is satisfied;
A storage processing unit for storing the temporary address in the second storage unit when the first determination unit determines that the first condition is satisfied;
If it is determined by the first determination means that the first condition is not satisfied, the data is not stored in the temporary address storage area or the first address is stored in the temporary address storage area. The second condition that time data indicating a storage time before the storage time of the data stored in the storage area is stored, and the storage area of the temporary address is stored in the top storage area. Second determination means for determining which of the third conditions that time data indicating a storage time later than the storage time of the data is stored is satisfied;
When it is determined by the second determination means that the second condition is satisfied, the temporary address in the processing of the first determination means is determined between the temporary address and the address of the head storage area. If the second determination means determines that the third condition is satisfied, the temporary address in the processing of the first determination means is changed to the next address of the temporary address. Temporary address changing means for
Repetitive control means for repeating the processing by the first determination means, the second determination means and the temporary address change means until the storage processing means stores the temporary address in the second storage means;
Consists of
Said computer, said temporary address setting means, said first determination means, the storage processing unit, according to claim 6, wherein the second determining means, characterized in that function as the temporary address change means and repeat control means The program described in. A computer-readable recording medium in which the program according to claim 6 or 7 is recorded.

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