Recognition time adjustment device, energy storage device, recognition time adjustment method and program

Abstract

This invention provides a recognition time adjustment device, an energy storage device, a recognition time adjustment method, and a program that can adjust the recognition time recognized by a clock signal and recognize time with high accuracy. [Solution] The recognition time adjustment device comprises an oscillator that oscillates at a predetermined oscillation frequency, a time information acquisition unit that acquires time information indicating the current time, and a microcomputer that adjusts the recognition time recognized by a clock signal obtained from the oscillation frequency based on the temperature characteristics of the oscillator and the time information.

Description

Technical Field

[0001] The present disclosure relates to a recognition time adjustment device, a power storage device, a recognition time adjustment method, and a program.

Background Art

[0002] Conventionally, a power storage device including a rechargeable secondary battery is equipped with a control device including a microcomputer to control charging and discharging. In such a control device, the microcomputer recognizes time and timing using a clock signal generated based on the oscillation frequency of an oscillator such as a crystal (see, for example, Patent Document 1).

[0003] The microcomputer recognizes time by counting the clock count indicating the number of pulses included in the clock signal. Therefore, in order to recognize accurate time, a high-precision clock signal without deviation in pulse timing is required.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the clock signal includes an error in the clock frequency that depends on the component accuracy of the oscillator serving as the clock source. Further, the oscillator has temperature characteristics in which the oscillation frequency varies with temperature. Therefore, there is a problem in that a deviation occurs in the pulse timing of the clock signal due to the component accuracy of the oscillator and the temperature environment, and as a result, a deviation occurs in the recognition time recognized by the microcomputer.

[0006] This disclosure has been made in view of the problems in the above-mentioned prior art, and aims to provide a recognition time adjustment device, an energy storage device, a recognition time adjustment method, and a program that can adjust the recognition time recognized by a clock signal and recognize time with high accuracy. [Means for solving the problem]

[0007] The recognition time adjustment device relating to this disclosure is An oscillator that oscillates at a predetermined oscillation frequency, A time information acquisition unit that acquires time information indicating the current time, A microcomputer adjusts the recognition time, which is recognized by a clock signal obtained from the oscillation frequency, based on the temperature characteristics of the oscillator and the time information. It is equipped with.

[0008] Furthermore, the energy storage device related to this disclosure is The above-mentioned recognition time adjustment device, Rechargeable secondary batteries and It is equipped with.

[0009] Furthermore, the recognition time adjustment method relating to this disclosure is: Obtain time information indicating the current time, Based on the temperature characteristics of an oscillator oscillating at a predetermined oscillation frequency and the time information, the recognition time recognized by the clock signal obtained from the oscillation frequency is adjusted.

[0010] Furthermore, the program relating to this disclosure causes a computer to execute the recognition time adjustment method described above. [Effects of the Invention]

[0011] According to this disclosure, the recognition time recognized by the clock signal can be adjusted, enabling accurate recognition of time. [Brief explanation of the drawing]

[0012] [Figure 1]It is a block diagram showing an example of the configuration of the power storage device according to this embodiment. [Figure 2] It is a block diagram showing an example of the main part of the control system of the microcomputer according to this embodiment. [Figure 3] It is a schematic diagram for explaining the time recognition of the microcomputer in FIG. 1. [Figure 4] It is a graph showing an example of the temperature characteristics of the oscillator in FIG. 1.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments, and various modifications can be made without departing from the gist of the present disclosure. Also, in each figure, those with the same reference numerals are the same or corresponding ones, which is common throughout the entire specification.

[0014] [Configuration of Power Storage Device 100] FIG. 1 is a block diagram showing an example of the configuration of the power storage device 100 according to this embodiment. As shown in FIG. 1, the power storage device 100 includes a control device 1 and a secondary battery 2.

[0015] The secondary battery 2 is a rechargeable battery and is composed of one or more secondary battery cells. When the secondary battery 2 is composed of a plurality of secondary battery cells, the secondary battery 2 is configured, for example, by connecting the secondary battery cells in series. The secondary battery 2 is, for example, a nickel-hydrogen secondary battery. Note that the type of the secondary battery 2 is not limited to this example, and it may be a secondary battery other than a nickel-hydrogen secondary battery such as a lithium-ion secondary battery.

[0016] In this example, one secondary battery 2 is provided, but it is not limited to this, and two or more secondary batteries 2 may be provided. When a plurality of secondary batteries 2 are provided, the plurality of secondary batteries 2 are connected in series or in parallel, for example.

[0017] The control device 1 controls the entire power storage device 100. For example, based on information regarding the secondary battery 2 such as the battery temperature of the secondary battery 2 supplied from sensors (not shown) provided in the power storage device 100, the control device 1 performs charge / discharge control for the secondary battery 2 and various controls such as measurement of the state of charge (SOC) indicating the charge state of the secondary battery 2.

[0018] Also, in the present embodiment, the control device 1 is a recognition time adjustment device that performs recognition time adjustment processing for adjusting the recognition time recognized by the microcomputer 10 described later based on a clock signal. Details of the recognition time adjustment processing will be described later. Here, the clock signal is a signal that periodically outputs a pulse waveform at a predetermined clock frequency. In the following description, "time" is assumed to be a concept having a length between two predetermined time points.

[0019] The control device 1 includes a microcomputer (hereinafter, appropriately referred to as "microcontroller") 10, an oscillator 20, a time information acquisition unit 30, and a temperature sensor 40. Note that in FIG. 1, only the processing units related to the features of the present embodiment among the functions provided in the control device 1 are shown.

[0020] The oscillator 20 is, for example, a crystal oscillator, and oscillates by periodically vibrating at a predetermined frequency by applying a voltage. The oscillator 20 outputs a voltage amplitude signal including the oscillation frequency generated by the oscillation.

[0021] The time information acquisition unit 30 acquires time information indicating the current time and outputs the acquired time information to the microcontroller 10.

[0022] The time information acquisition unit 30 is, for example, a communication interface that acquires time information from an external NTP (Network Time Protocol) server via a network. In this case, the time information acquisition unit 30 acquires the current time transmitted from the NTP server and outputs the acquired time as time information.

[0023] Furthermore, the time information acquisition unit 30 is, for example, an RTC (Real Time Clock) circuit. The RTC circuit is composed of a clock IC (Integrated Circuit) including an oscillator circuit. In this case, the time information acquisition unit 30 generates a clock signal for measuring the time and measures the current time, including the year, month, day, hour, minute, and second. The time information acquisition unit 30 then outputs the measured current time as time information.

[0024] The time information acquisition unit 30 may include, for example, both a communication interface for communicating with an NTP server and an RTC circuit. When the time information acquisition unit 30 is online and connected to a network, it outputs time information indicating the current time obtained from the NTP server via the communication interface. When the time information acquisition unit 30 is offline and not connected to a network, it outputs time information indicating the current time measured by the RTC circuit.

[0025] The temperature sensor 40 is located near the oscillator 20, measures the temperature of the oscillator 20, and outputs the result to the microcontroller 10.

[0026] The microcontroller 10 generates a clock signal based on the voltage amplitude signal supplied from the oscillator 20, and performs recognition time adjustment processing based on the generated clock signal and the time information output from the time information acquisition unit 30. The microcontroller 10 includes a clock generation unit 11, a correction unit 12, and a storage unit 13.

[0027] The clock generation unit 11 generates a clock signal of a predetermined frequency based on the oscillation frequency of the oscillator 20, which is included in the voltage amplitude signal supplied from the oscillator 20.

[0028] The correction unit 12 performs recognition time adjustment processing to adjust the recognition time recognized by the microcontroller 10 based on the temperature correction table 130 stored in the memory unit 13, the temperature of the oscillator 20 measured by the temperature sensor 40, and the time information acquired by the time information acquisition unit 30. The temperature correction table 130 is a lookup table that associates the temperature of the oscillator 20 with the frequency deviation of the oscillation frequency. The temperature correction table 130 is used when adjusting the recognition time by the microcontroller 10.

[0029] Specifically, in the recognition time adjustment process, the correction unit 12 adjusts the recognition time of the microcontroller 10 based on the temperature of the oscillator 20, by referring to the temperature correction table 130 and correcting the clock frequency error caused by the temperature characteristics of the oscillator 20. The correction unit 12 also adjusts the recognition time of the microcontroller 10 based on the time information acquired by the time information acquisition unit 30.

[0030] The storage unit 13 is composed of, for example, a non-volatile semiconductor memory (so-called flash memory), an HDD (Hard Disk Drive), or an SSD (Solid State Drive), and stores various data used by the correction unit 12. In this embodiment, the storage unit 13 stores the temperature correction table 130.

[0031] Figure 2 is a block diagram showing an example of the main components of the control system of the microcontroller 10 according to this embodiment. As shown in Figure 2, the microcontroller 10 includes a CPU (Central Processing Unit) 1001, a ROM (Read Only Memory) 1002, a RAM (Random Access Memory) 1003, and a storage device 1004, etc. The various components constituting the control device 1 are connected by a bus 1005.

[0032] The CPU 1001 reads a program corresponding to the processing content from the ROM 1002, loads it into the RAM 1003, and controls the operation of the energy storage device 100 in cooperation with the loaded program. At this time, various data such as the temperature compensation table 130 stored in the storage device 1004, which corresponds to the storage unit 13 in Figure 1, is referenced. The storage device 1004 stores various data used for calculations etc. by the CPU 1001. In this embodiment, the storage device 1004 corresponds to the storage unit 13 in Figure 1.

[0033] [Time recognition by microcontroller 10] The recognition of time by the microcontroller 10 according to this embodiment will now be described. Generally, the microcontroller 10 recognizes time by counting the number of clock pulses, which indicates the number of pulses in the clock signal, and recognizing a predetermined unit of time.

[0034] (Recognition time lag by microcontroller 10) Incidentally, the clock signal contains an error in the clock frequency that depends on the component precision of the oscillator 20, which is the clock source. In contrast, the microcontroller 10 has a preset tolerance range that indicates the range of acceptable errors in the clock frequency. Therefore, as long as the clock frequency is within the tolerance range, the microcontroller 10 can recognize the time with approximately accuracy.

[0035] However, even if the clock frequency is within the acceptable tolerance range, over the long term, the time recognized by the microcontroller 10 will gradually drift due to the clock frequency error.

[0036] Figure 3 is a schematic diagram illustrating the time recognition of the microcontroller 10 in Figure 1. Figure 3 shows the time recognized by the microcontroller 10 when the time information acquisition unit 30 acquires time information at certain times T1 and T2.

[0037] In the example shown in Figure 3, first, when the time information acquisition unit 30 acquires the first time information at a certain time T1, the microcontroller 10 starts measuring time. Next, when the time information acquisition unit 30 acquires the second time information at a time T2, which is a predetermined time after time T1, the microcontroller 10 stops measuring time.

[0038] Here, the time information input interval, which indicates the interval at which time information is input, is defined as "T2-T1," and the recognition time, which indicates the time recognized by the microcontroller 10 within the time information input interval T2-T1, is defined as "X." In this case, the relationship between the time information input interval T2-T1 and the recognition time X is as shown below, depending on the error value of the clock frequency.

[0039] For example, if there is no error in the clock frequency, the clock frequency will be the same as the reference clock frequency, and therefore the length of the clock signal pulse will also be the specified length. In other words, the number of clocks during the time information input interval T2-T1 is the specified number of clocks, so the relationship between the time information input interval T2-T1 and the recognition time X is "X = T2-T1".

[0040] On the other hand, for example, if the error in the clock frequency is a positive value, the clock frequency is higher than the reference clock frequency, so the length of the clock signal pulse will be shorter than the specified length. In other words, the number of clock cycles during the time information input interval T2-T1 will be greater than the specified number of clock cycles, so the relationship between the time information input interval T2-T1 and the recognition time X will be "X > T2-T1".

[0041] Furthermore, for example, if the error in the clock frequency is a negative value, the clock frequency is lower than the reference clock frequency, and therefore the length of the clock signal pulse becomes longer than the specified length. In other words, the number of clocks during the time information input interval T2-T1 is less than the specified number of clocks, so the relationship between the time information input interval T2-T1 and the recognition time X is "X <T2-T1」となる。

[0042] Let's consider a more specific case where the time information input interval T2-T1 is 1 hour. For example, if the clock frequency error is +0.5%, the clock frequency will be 1.005 times the reference clock frequency. Therefore, the recognition time X by the microcontroller 10 will be 1 hour and 18 seconds (= 1 hour × 1.005), which is longer than the time information input interval T2-T1. Also, for example, if the clock frequency error is -0.5%, the clock frequency will be 0.995 times the reference clock frequency. Therefore, the recognition time X by the microcontroller 10 will be 59 minutes and 42 seconds (= 1 hour × 0.995), which is shorter than the time information input interval T2-T1.

[0043] Thus, due to errors in the clock frequency, the microcontroller 10 has difficulty recognizing the time accurately. Therefore, in order for the microcontroller 10 to recognize the time accurately, it is necessary to correct the discrepancy in the recognition time of the microcontroller 10 caused by errors in the clock frequency, which depend on the component precision of the oscillator 20.

[0044] (Temperature characteristics of oscillator 20) On the other hand, the oscillator 20, which serves as the clock source, has a temperature characteristic in which its oscillation frequency fluctuates depending on the temperature. Therefore, the oscillation frequency of the voltage amplitude signal output from the oscillator 20 fluctuates according to the operating temperature environment of the energy storage device 100.

[0045] Figure 4 is a graph showing an example of the temperature characteristics of the oscillator 20 in Figure 1. In Figure 4, the horizontal axis represents temperature [°C], and the vertical axis represents the frequency deviation of the oscillation frequency [ppm].

[0046] In this example, when the oscillator 20 is at a temperature of +25°C, there is no frequency deviation in the oscillation frequency (±0 ppm). As the temperature of the oscillator 20 rises from +25°C, the frequency deviation increases to the negative side, and then begins to decrease from around +65°C. Conversely, as the temperature of the oscillator 20 decreases from +25°C, the frequency deviation increases to the positive side.

[0047] As the oscillator 20 has temperature characteristics, the clock frequency will have an error based on the frequency deviation that occurs depending on the operating temperature environment of the energy storage device 100. Therefore, in order for the microcontroller 10 to recognize the time accurately, it is also necessary to correct for the discrepancy in the recognition time of the microcontroller 10 that occurs due to the deviation in the oscillation frequency caused by the temperature characteristics of the oscillator 20.

[0048] Therefore, in this embodiment, the energy storage device 100 performs a recognition time adjustment process to adjust the recognition time of the microcontroller 10, taking into account the deviation of the oscillation frequency due to the temperature characteristics of the oscillator 20 and the error in the clock frequency which depends on the component precision of the oscillator 20.

[0049] [Recognition time adjustment process] The recognition time adjustment process will now be explained. In the recognition time adjustment process, the first adjustment process and the second adjustment process shown below are performed in order to correct the recognition time of the microcontroller 10.

[0050] The first adjustment process is a process that corrects the delay in the recognition time of the microcontroller 10 caused by the deviation in the oscillation frequency based on the temperature characteristics of the oscillator 20.

[0051] First, the correction unit 12 refers to the temperature correction table 130 stored in the memory unit 13 based on the temperature of the oscillator 20 measured by the temperature sensor 40, and identifies the frequency deviation of the clock frequency at the current temperature of the oscillator 20. Next, the correction unit 12 determines the number of clocks that the microcontroller 10 can accurately recognize per unit time based on the identified frequency deviation of the clock frequency. Then, the correction unit 12 sets the current number of clocks per unit time to the determined number of clocks.

[0052] In this way, by performing the first adjustment process, the delay in the recognition time of the microcontroller 10 caused by the deviation in the oscillation frequency based on the temperature characteristics of the oscillator 20 can be eliminated.

[0053] Specifically, for example, when the microcontroller 10 recognizes a unit of time with 10,000 clock cycles, a frequency deviation may occur due to the temperature characteristics of the oscillator 20, resulting in the number of clock cycles required for the microcontroller 10 to recognize a unit of time becoming 10,001. In this case, the correction unit 12 identifies the frequency deviation of the clock frequency at the current temperature of the oscillator 20 through a first adjustment process. Then, based on the identified frequency deviation, the correction unit 12 sets the number of clock cycles for the microcontroller 10 to recognize a unit of time from 10,000 to 10,001.

[0054] In this way, the correction unit 12 adjusts the number of clocks for which the microcontroller 10 recognizes a unit of time, taking into account the increase or decrease in the number of clocks caused by the frequency deviation of the oscillation frequency, during the first adjustment process.

[0055] The second adjustment process corrects the discrepancy in the recognition time of the microcontroller 10 caused by the error in the clock frequency due to the component precision of the oscillator 20.

[0056] First, when the time information acquisition unit 30 acquires two pieces of time information at a predetermined time interval, the correction unit 12 identifies the number of clocks corresponding to the recognition time recognized by the microcontroller 10 in the time information input interval based on the two pieces of time information. Next, the correction unit 12 determines the number of clocks that the microcontroller 10 will accurately recognize as a unit of time, based on the identified number of clocks, so that the microcontroller 10 recognizes the time of the time information input interval at that number of clocks. Then, the correction unit 12 sets the current number of clocks per unit of time to the determined number of clocks.

[0057] In this way, by performing the second adjustment process, the discrepancy in the recognition time of the microcontroller 10 caused by the clock frequency error based on the component precision of the oscillator 20 can be eliminated.

[0058] Specifically, for example, if the time information input interval is 1 hour and the recognition time of the microcontroller 10 at that time is 1 hour and 18 seconds, the correction unit 12 adjusts the recognition time of the microcontroller 10 so that the recognition time of the microcontroller 10 in the time information input interval becomes 1 hour. In this case, the correction unit 12 sets the number of clocks per unit time based on the number of clocks counted during the time information input interval so that the microcontroller 10 recognizes 1 hour based on the number of clocks counted during the time information input interval.

[0059] In this way, the correction unit 12 adjusts the number of clocks for which the microcontroller 10 recognizes a unit of time, taking into account the increase or decrease in the number of clocks caused by the error in the clock frequency, during the second adjustment process.

[0060] Although the first and second adjustment processes can each be performed independently to correct the clock frequency error, it is preferable that the second adjustment process be performed after the first adjustment process. This is to prevent the adjustment of the recognition time due to the clock frequency error from being affected by the deviation in the oscillation frequency based on the temperature characteristics of the oscillator 20.

[0061] [Examples of use of energy storage device 100] For example, the energy storage device 100 according to this embodiment is installed as a battery in an electric vehicle. The microcontroller 10 of the control device 1 performs a process to measure the State of Charge (SOC) of the secondary battery 2 by integrating the value of the current flowing during a predetermined recognition time.

[0062] For example, the correction unit 12 performs a first adjustment process when the time information acquisition unit 30 cannot properly acquire time information, such as during operation, to correct the discrepancy in recognition time due to the frequency deviation of the oscillation frequency. Then, the correction unit 12 performs a second adjustment process when the time information acquisition unit 30 can properly acquire time information, such as while the secondary battery 2 is being charged at a charging station, to correct the discrepancy in recognition time caused by errors in the clock frequency.

[0063] As described above, in the energy storage system 100 according to this embodiment, the microcontroller 10 adjusts the recognition time based on the temperature characteristics of the oscillator 20 and the time information acquired by the time information acquisition unit 30. This adjusts for the recognition time deviation caused by the oscillation frequency deviation due to the temperature characteristics of the oscillator 20 and the recognition time deviation caused by the clock frequency error due to the component precision of the oscillator 20. As a result, the microcontroller 10 can recognize the time with high accuracy.

[0064] Although this embodiment has been described above, this disclosure is not limited to the embodiments described above, and various modifications and applications are possible without departing from the spirit of this disclosure. For example, in this embodiment, the case in which the control device 1 is mounted on the energy storage device 100 has been described, but this is not limited to this, and for example, the control device 1 may be mounted on any device that requires accurate time recognition. [Explanation of symbols]

[0065] 1 Control device 2 Secondary battery 10 Microcomputers 11 Clock generation unit 12 Correction section 13 Storage section 20 Oscillators 30 Time information acquisition section 40 Temperature Sensors 100 Energy Storage Devices 130 Temperature Compensation Table

Claims

1. An oscillator that oscillates at a predetermined oscillation frequency, A time information acquisition unit that acquires time information indicating the current time, A microcomputer adjusts the recognition time, which is recognized by a clock signal obtained from the oscillation frequency, based on the temperature characteristics of the oscillator and the time information. Equipped with Recognition time adjustment device.

2. The aforementioned microcomputer is The system has a storage unit that stores a temperature correction table relating the temperature of the oscillator to the frequency deviation of the oscillation frequency. Based on the temperature of the oscillator, the recognition time deviation caused by the deviation in the oscillation frequency is adjusted by referring to the temperature correction table. The recognition time adjustment device according to claim 1.

3. The aforementioned microcomputer is Based on multiple time information acquired at predetermined time intervals, the system adjusts the recognition time deviation caused by the clock frequency error based on the tolerance for the oscillator. The recognition time adjustment device according to claim 1.

4. The aforementioned time information acquisition unit, It is a communication interface that connects to an NTP server. The recognition time adjustment device according to claim 1.

5. The aforementioned time information acquisition unit, This is an RTC circuit. The recognition time adjustment device according to claim 1.

6. The recognition time adjustment device according to claim 1, Rechargeable secondary batteries and Equipped with Energy storage device.

7. Obtain time information indicating the current time, Based on the temperature characteristics of an oscillator oscillating at a predetermined oscillation frequency and the time information, the recognition time recognized by the clock signal obtained from the oscillation frequency is adjusted. Recognition time adjustment method.

8. A program for causing a computer to execute the recognition time adjustment method described in claim 7.

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