Voltage Measurement System

Abstract

A voltage measurement system (10) comprises: a first reference signal transmission device (communication device 30) having a first master oscillator (36) for generating a first master clock signal, and a first reference signal generating circuit (33) for generating a first reference signal on the basis of the first master clock signal; and a first voltage measurement device (40) having a first slave oscillator (46), a first correction circuit (43) for correcting the oscillation frequency of the first slave oscillator (46) on the basis of the first reference signal, and a first voltage measurement circuit (48), the voltage measurement system (10) having a normal mode for transmission / reception of a command signal between the first reference signal transmission device (communication device 30) and the first voltage measurement device (40), and a correction mode for transmitting the first reference signal from the first reference signal transmission device (communication device 30) to the first voltage measurement device (40) and using the first reference signal to synchronize the oscillation frequency of the first slave oscillator (46) to the oscillation frequency of the first master oscillator (36).

Description

[Technical Field]

[0001] The present disclosure relates to a voltage measurement system. [Background technology]

[0002] Conventionally, a voltage measurement system used in a battery module system including a battery module is known (see, for example, Patent Document 1). The battery module has a plurality of battery cells connected in series. The voltage measurement system has a plurality of voltage measurement devices and a control device for controlling them. For example, one of the plurality of voltage measurement devices can measure the current flowing through the battery module from the voltage value applied to a resistive element connected in series to the battery module, and each of the other voltage measurement devices can measure the voltage of the battery cell. This makes it possible to simultaneously measure the voltage of each battery cell and the current flowing through each battery cell.

[0003] The voltage and current of a battery module can fluctuate over time depending on the state of the load connected to the battery module. Therefore, if the timing of voltage and current measurements is misaligned, the state of the battery module (such as the charging rate and degradation state) cannot be determined with high accuracy. Therefore, conventional voltage measurement systems attempt to align the measurement timing of each voltage measurement device by determining the measurement timing of each voltage measurement device based on a clock signal from an oscillator in each voltage measurement device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-141062 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the oscillation frequencies of the oscillators in each voltage measurement device may differ, which may cause the measurement timing of each voltage measurement device to differ. Therefore, even if measurements are performed based on the clock signal from the oscillator in each voltage measurement device, it is not possible to accurately determine the state of the battery module.

[0006] The present disclosure is intended to solve such problems, and aims to provide a voltage measurement system that can control the measurement timing of a voltage measurement device with high precision. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, one aspect of a voltage measurement system according to the present disclosure is a voltage measurement system for measuring the voltage of a battery cell, comprising: a first reference signal transmission device having a first master oscillator that generates a first master clock signal and a first reference signal generation circuit that generates a first reference signal based on the first master clock signal; a first voltage measurement device having a first slave oscillator that generates a first clock signal, a first correction circuit that corrects the oscillation frequency of the first slave oscillator based on the first reference signal, a first voltage measurement circuit, and a first measurement control circuit that controls the first voltage measurement circuit based on the first clock signal; and the voltage measurement system has a normal mode in which command signals are transmitted and received between the first reference signal transmission device and the first voltage measurement device, and a correction mode in which the first reference signal is transmitted from the first reference signal transmission device to the first voltage measurement device and the oscillation frequency of the first slave oscillator is synchronized with the oscillation frequency of the first master oscillator using the first reference signal. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a voltage measurement system that can control the measurement timing of a voltage measurement device with high precision. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a block diagram showing the functional configuration of a voltage measurement system according to the first embodiment. [Figure 2] FIG. 2 is a flowchart showing the flow of operations in the correction mode in the communication circuit according to the first embodiment. [Figure 3] FIG. 3 is a flowchart showing the flow of operations in the correction mode in the voltage measuring device according to the first embodiment. [Figure 4] FIG. 4 is a schematic graph showing an example of each signal according to the first embodiment. [Figure 5] FIG. 5 is a block diagram illustrating a functional configuration of the correction circuit according to the first embodiment. [Figure 6] FIG. 6 is a diagram showing measurement timing before correction in the voltage measurement system according to the first embodiment. [Figure 7] FIG. 7 is a diagram showing the measurement timing after correction in the voltage measurement system according to the first embodiment. [Figure 8] FIG. 8 is a block diagram showing the functional configuration of the voltage measurement system according to the second embodiment. [Figure 9] FIG. 9 is a block diagram showing the functional configuration of a voltage measurement system according to the third embodiment. [Figure 10] FIG. 10 is a block diagram showing the functional configuration of a voltage measurement system according to the fourth embodiment. [Figure 11] FIG. 11 is a block diagram showing the functional configuration of a voltage measurement system according to the fifth embodiment. [Figure 12] FIG. 12 is a block diagram showing the functional configuration of a voltage measurement system according to the sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, and the arrangement and connection of the components shown in the following embodiments are merely examples and are not intended to limit the present disclosure.

[0011] Furthermore, each figure is a schematic diagram and is not necessarily an exact representation. Therefore, the scales and the like do not necessarily match in each figure. In each figure, the same reference numerals are used to denote substantially the same components, and redundant explanations will be omitted or simplified.

[0012] (Embodiment 1) A voltage measurement system according to a first embodiment will be described.

[0013] [1-1. Overall structure] The overall configuration of a voltage measurement system according to this embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing the functional configuration of a voltage measurement system 10 according to this embodiment. Fig. 1 also shows a battery cell 21, which is the object of measurement by the voltage measurement system 10, a resistive element 22, and a control device 20 that controls the voltage measurement system 10.

[0014] The control device 20 is a device that controls the voltage measurement system 10. The control device 20 transmits a command signal to the voltage measurement system 10 to control the voltage measurement system 10. For example, the control device 20 transmits a command signal to the voltage measurement system 10 to cause the voltage measurement system 10 to start measuring a voltage. The control device 20 can be realized using, for example, an MCU (Micro-Controller Unit) or the like.

[0015] The voltage measurement system 10 is a system that measures the voltage of a battery cell 21. In this embodiment, the voltage measurement system 10 also measures the current flowing through the battery cell 21. The voltage measurement system 10 measures the voltage across a resistive element 22 connected in series to the battery cell 21, and measures the current flowing through the resistive element 22, i.e., the current flowing through the battery cell 21, from the voltage and the resistance value of the resistive element 22. In this embodiment, the voltage measurement system 10 includes a communication device 30 and voltage measurement devices 40 and 50. The communication device 30 and the voltage measurement devices 40 and 50 transmit and receive command signals and the like using daisy-chain communication paths. Furthermore, a transformer, for example, may be used for transmitting and receiving signals between the communication device 30 and the voltage measurement device 40, and between the voltage measurement devices 40 and 50. This allows signals to be transmitted and received while maintaining insulation between the devices. In this embodiment, the voltage measurement system 10 includes two voltage measurement devices 40 and 50, but may include three or more voltage measurement devices in accordance with the number of battery cells to be measured.

[0016] The voltage measurement system 10 has a normal mode and a correction mode. The normal mode is a mode in which command signals are transmitted and received between a communication device 30, which is an example of a first reference signal transmission device, and the voltage measurement devices 40, 50. The correction mode is a mode in which a reference signal is transmitted from the communication device 30 to the voltage measurement devices 40, 50, and the reference signal is used to synchronize the oscillation frequencies of the slave oscillators 46, 56 included in each of the voltage measurement devices 40, 50 with the oscillation frequency of the master oscillator 36 included in the communication device 30.

[0017] The communication device 30 is a device that communicates with the control device 20 and the voltage measuring devices 40, 50. The communication device 30 is an example of a first reference signal transmitting device that transmits a reference signal for correcting the oscillation frequencies of the slave oscillators 46, 56 that the voltage measuring devices 40, 50 have, respectively. The communication device 30 has a communication circuit 34, a master oscillator 36, a reference signal generating circuit 33, a mode control circuit 35, and a multiplexer 32.

[0018] The communication circuit 34 is a circuit that transmits and receives command signals between the control device 20 and the voltage measuring devices 40, 50. For example, when the communication circuit 34 receives a command signal from the control device 20 instructing the start of voltage measurement, the communication circuit 34 transmits the command signal (or a signal corresponding to the command signal) to the voltage measuring devices 40, 50. Furthermore, when the communication circuit 34 receives a command signal from the control device 20 instructing the switching to the normal mode or the correction mode, the communication circuit 34 transmits the command signal (or a signal corresponding to the command signal) to the voltage measuring devices 40, 50. Furthermore, when the communication circuit 34 receives a command signal instructing the switching to the correction mode, the communication circuit 34 transmits a signal to the reference signal generating circuit 33 instructing the generation of a reference signal.

[0019] The master oscillator 36 is an example of a first master oscillator that generates a master clock signal. The master clock signal is an example of a first master clock signal that is used to generate a reference signal. The master clock signal generated by the master oscillator 36 is transmitted to the reference signal generation circuit 33 and the communication circuit 34.

[0020] The reference signal generation circuit 33 is an example of a first reference signal generation circuit that generates a reference signal based on a master clock signal in the correction mode. The reference signal generation circuit 33 generates a reference signal in response to a command signal received from the communication circuit 34. The reference signal is an example of a first reference signal generated based on a master clock signal. For example, the reference signal generation circuit 33 generates one pulse every 10 clocks of the master clock signal, repeating this process 10 times. The pulse train generated in this manner can be used as a reference signal. This allows the generation of a reference signal corresponding to a predetermined number of clocks included in the master clock signal.

[0021] The mode control circuit 35 is a circuit that controls the multiplexer 32 depending on the mode. The mode control circuit 35 switches between the normal mode and the correction mode based on a command signal transmitted from the communication circuit 34. In the normal mode, the mode control circuit 35 causes the multiplexer 32 to transmit a command signal, and in the correction mode, the mode control circuit 35 causes the multiplexer 32 to transmit a reference signal.

[0022] The multiplexer 32 is a circuit that transmits and receives command signals and reference signals. The multiplexer 32 switches between transmitting and receiving signals based on a command signal from the mode control circuit 35. The multiplexer 32 transmits and receives command signals in the normal mode, and transmits and receives reference signals in the correction mode.

[0023] The voltage measuring device 40 is a device that measures voltage at a timing based on a first clock signal generated by a slave oscillator 46. In this embodiment, the voltage measuring device 40 functions as a current measuring device that measures the current flowing through the resistive element 22 and the battery cell 21 by measuring the voltage across the resistive element 22. The voltage measuring device 40 is also an example of a first voltage measuring device that corrects the oscillation frequency of the slave oscillator 46 based on a reference signal received from the communication device 30. When the voltage measuring device 40 receives a command signal from the communication device 30 instructing it to transition to the correction mode in the normal mode, it transitions to the correction mode. The voltage measuring device 40 includes a selection circuit 41, a multiplexer 42, a correction circuit 43, a communication circuit 44, a mode control circuit 45, a slave oscillator 46, a measurement control circuit 47, and a voltage measurement circuit 48.

[0024] The selection circuit 41 is an example of a first selection circuit that transmits and receives a command signal and a reference signal. The selection circuit 41 switches between transmitting and receiving signals based on a command signal from the mode control circuit 45. In the normal mode, the selection circuit 41 transmits and receives a command signal to and from the communication device 30, and in the correction mode, the selection circuit 41 receives a reference signal and transmits the reference signal to the correction circuit 43 and the multiplexer 42.

[0025] The multiplexer 42 is an example of a first multiplexer that transmits and receives a command signal and a reference signal. The multiplexer 42 switches between transmitting and receiving signals based on a command signal from the mode control circuit 45. The multiplexer 42 transmits and receives command signals in the normal mode and transmits and receives reference signals in the correction mode. In the correction mode, the multiplexer 42 transmits the reference signal to other devices in the voltage measurement system 10. In this embodiment, the multiplexer 42 transmits the reference signal to the voltage measurement device 50.

[0026] The correction circuit 43 is an example of a first correction circuit that corrects the oscillation frequency of the slave oscillator 46 based on a reference signal. In the correction mode, the correction circuit 43 receives the reference signal from the selection circuit 41. The reference signal is, for example, a signal that indicates a time corresponding to a predetermined number of master clock signal trains. The correction circuit 43 corrects the oscillation frequency of the slave oscillator 46 so that the predetermined number of first clock signal trains are included within the time indicated by the reference signal. The correction method used by the correction circuit 43 will be described later.

[0027] The communication circuit 44 is an example of a first communication circuit that transmits and receives command signals between the communication device 30 and the voltage measurement device 50. For example, when the communication circuit 44 receives a command signal from the communication device 30 via the selection circuit 41 instructing the start of voltage measurement, the communication circuit 44 transmits the command signal (or a signal corresponding to the command signal) to the measurement control circuit 47 and the voltage measurement device 50. Furthermore, when the communication circuit 44 receives a command signal from the communication device 30 instructing switching to the normal mode or the correction mode, the communication circuit 44 transmits the command signal (or a signal corresponding to the command signal) to the mode control circuit 45 and the voltage measurement device 50.

[0028] The mode control circuit 45 is an example of a first mode control circuit that controls the multiplexer 42 and the selection circuit 41 depending on the mode. The mode control circuit 45 also has a function of causing the correction circuit 43 to start correction. The mode control circuit 45 switches between the normal mode and the correction mode based on a command signal transmitted from the communication circuit 44. In the normal mode, the mode control circuit 45 causes the multiplexer 42 and the selection circuit 41 to transmit a command signal, and in the correction mode, causes the multiplexer 42 and the selection circuit 41 to transmit a reference signal.

[0029] The slave oscillator 46 is an example of a first slave oscillator that generates a first clock signal. The first clock signal generated by the slave oscillator 46 is transmitted to the correction circuit 43, the communication circuit 44, and the measurement control circuit 47.

[0030] Measurement control circuit 47 is an example of a first measurement control circuit that controls voltage measurement circuit 48 based on a first clock signal. Measurement control circuit 47 causes voltage measurement circuit 48 to measure voltage at a period determined based on the first clock signal, for example.

[0031] Voltage measurement circuit 48 is an example of a first voltage measurement circuit that measures the voltage between two terminals. In this embodiment, voltage measurement circuit 48 measures the voltage between both ends of resistor element 22. Voltage measurement circuit 48 includes, for example, an ADC (Analog-Digital Converter), and converts an analog measurement value into a digital signal for output.

[0032] The voltage measuring device 50 is a device that measures voltage at a timing based on a second clock signal generated by a slave oscillator 56. In this embodiment, the voltage measuring device 50 measures the voltage across the battery cell 21. The voltage measuring device 50 is also an example of a second voltage measuring device that corrects the oscillation frequency of the slave oscillator 56 based on a reference signal received from the communication device 30 via the voltage measuring device 40. When the voltage measuring device 50 receives a command signal from the communication device 30 (via the voltage measuring device 40) indicating a transition to the correction mode in the normal mode, the voltage measuring device 50 transitions to the correction mode. The voltage measuring device 50 has a configuration similar to that of the voltage measuring device 40. The voltage measuring device 50 includes a selection circuit 51, a multiplexer 52, a correction circuit 53, a communication circuit 54, a mode control circuit 55, a slave oscillator 56, a measurement control circuit 57, and a voltage measurement circuit 58.

[0033] The selection circuit 51 is an example of a second selection circuit that transmits and receives a command signal and a reference signal. The selection circuit 51 switches between transmitting and receiving signals based on a command signal from the mode control circuit 55. In the normal mode, the selection circuit 51 transmits and receives a command signal to and from the voltage measuring device 40, and in the correction mode, the selection circuit 51 transmits and receives a reference signal and transmits the reference signal to the correction circuit 53 and the multiplexer 52.

[0034] The multiplexer 52 is an example of a second multiplexer that transmits and receives a command signal and a reference signal. The multiplexer 52 switches between transmitting and receiving signals based on a command signal from the mode control circuit 55. The multiplexer 52 transmits and receives a command signal in the normal mode, and transmits and receives a reference signal in the correction mode.

[0035] The correction circuit 53 is an example of a second correction circuit that corrects the oscillation frequency of the slave oscillator 56 based on a reference signal. In the correction mode, the correction circuit 53 receives the reference signal from the selection circuit 51. The reference signal is, for example, a signal that indicates a time corresponding to a predetermined number of master clock signal trains. The correction circuit 53 corrects the oscillation frequency of the slave oscillator 56 so that the predetermined number of second clock signal trains is included within the time indicated by the reference signal.

[0036] The communication circuit 54 is an example of a first communication circuit that transmits and receives command signals between the communication device 30 and the voltage measuring device 40. For example, when the communication circuit 54 receives a command signal from the voltage measuring device 40 via the selection circuit 51 instructing the start of voltage measurement, the communication circuit 54 transmits the command signal (or a signal corresponding to the command signal) to the measurement control circuit 57. Furthermore, when the communication circuit 54 receives a command signal from the voltage measuring device 40 instructing switching to the normal mode or the correction mode, the communication circuit 54 transmits the command signal (or a signal corresponding to the command signal) to the mode control circuit 55.

[0037] The mode control circuit 55 is an example of a second mode control circuit that controls the multiplexer 52 and the selection circuit 51 depending on the mode. The mode control circuit 55 also has a function of causing the correction circuit 53 to start correction. The mode control circuit 55 is switched between the normal mode and the correction mode based on a command signal transmitted from the communication circuit 54. In the normal mode, the mode control circuit 55 causes the multiplexer 52 and the selection circuit 51 to transmit a command signal, and in the correction mode, the mode control circuit 55 causes the multiplexer 52 and the selection circuit 51 to transmit a reference signal.

[0038] The slave oscillator 56 is an example of a second slave oscillator that generates a second clock signal. The second clock signal generated by the slave oscillator 56 is transmitted to the correction circuit 53, the communication circuit 54, and the measurement control circuit 57.

[0039] The measurement control circuit 57 is an example of a second measurement control circuit that controls the voltage measurement circuit 58 based on the second clock signal. The measurement control circuit 57 causes the voltage measurement circuit 58 to measure the voltage at a period determined based on the second clock signal, for example.

[0040] The voltage measurement circuit 58 is an example of a second voltage measurement circuit that measures the voltage between two terminals. In this embodiment, the voltage measurement circuit 58 measures the voltage between both ends of the battery cell 21. The voltage measurement circuit 58 includes, for example, an ADC, and converts an analog measurement value into a digital signal and outputs the digital signal.

[0041] [1-2. Correction method] A method for correcting the oscillation frequency of the slave oscillators 46, 56 according to this embodiment will be described with reference to FIGS. 2 to 4. FIG. 2 is a flowchart showing the flow of operations in a correction mode in the communication device 30 according to this embodiment. FIG. 3 is a flowchart showing the flow of operations in a correction mode in the voltage measuring device 40 according to this embodiment. FIG. 4 is a schematic graph showing an example of the state of each signal according to this embodiment. Graphs (a), (c), and (d) of FIG. 4 show the output timings of the master clock signal, the first clock signal, and the second clock signal, respectively. Graph (b) of FIG. 4 shows the time waveform of the reference signal.

[0042] First, the operation of the communication device 30 will be described with reference to FIGS.

[0043] As shown in FIG. 2, the communication device 30 transmits a correction command signal, which is a command signal instructing switching to the correction mode, to the voltage measuring device 40 (and the voltage measuring device 50) (S10).

[0044] Next, the communication device 30 determines whether or not an ACK has been received from the voltage measurement device 40 and the voltage measurement device 50 (S12). The ACK is a signal that is transmitted when each of the voltage measurement device 40 and the voltage measurement device 50 receives a correction command signal.

[0045] If the communication device 30 does not receive an ACK (No in S12), it repeats step S12.

[0046] When the communication device 30 receives the ACK (Yes in S12), the communication device 30 switches to the correction mode (S14). Specifically, when the communication circuit 34 receives the ACK, the communication circuit 34 transmits a command signal to the mode control circuit 35 to instruct the mode control circuit 35 to switch to the correction mode.

[0047] Next, the communication device 30 generates a reference signal and transmits it to the voltage measurement device 40 (and the voltage measurement device 50) (S16). Specifically, the communication circuit 34 transmits a command signal to the reference signal generation circuit 33 to start generating the reference signal. The reference signal generation circuit 33 generates the reference signal based on the master clock signal from the master oscillator 36. The master clock signal is a signal that is constantly and repeatedly output at a predetermined oscillation frequency, as shown in graph (a) of FIG. 4. The configuration of the reference signal is not particularly limited. In this embodiment, the reference signal generation circuit 33 repeats a predetermined number of times to generate one pulse signal every time a predetermined number of clocks of the master clock signal are output. A pulse signal train generated in this manner, such as that shown in graph (b) of FIG. 4, may be used as the reference signal. For example, if the reference signal includes 21 pulse signals generated every five master clock signal outputs, the period from the first pulse signal to the last pulse signal of the reference signal corresponds to the period during which 100 master clock signals are output.

[0048] Next, the communication device 30 determines whether a predetermined time has elapsed (S18). If the predetermined time has not elapsed (No in S18), the communication device 30 continues transmitting the reference signal. In this embodiment, the communication device 30 continues transmitting the reference signal for a time equivalent to the time from the start to the end of transmission of a predetermined number of pulse signals generated by the reference signal generation circuit 33.

[0049] Next, when a predetermined time has elapsed (Yes in S18), the communication device 30 stops transmitting the reference signal (S20) and switches to the normal mode (S22). Specifically, the communication circuit 34 transmits a command signal to the mode control circuit 35 to instruct it to switch to the normal mode. The communication circuit 34 also transmits a command signal to the reference signal generation circuit 33 to instruct it to stop generating the reference signal.

[0050] Next, the operation of the voltage measuring device 40 will be described with reference to FIGS.

[0051] The voltage measuring device 40 receives the correction command signal from the communication device 30 (S30). Specifically, the communication circuit 44 receives the correction command signal via the selection circuit 41.

[0052] Next, the voltage measuring device 40 transmits an ACK to the communication device 30 (S32). Specifically, the communication circuit 44 transmits the ACK to the communication device 30 via the selection circuit 41.

[0053] Next, the voltage measuring device 40 switches to the correction mode (S34). Specifically, after transmitting the ACK, the communication circuit 44 transmits a command signal to the mode control circuit 45 to instruct the mode control circuit 45 to switch to the correction mode.

[0054] Next, the voltage measuring device 40 determines whether or not the reference signal has been received (S36). If the voltage measuring device 40 has not received the reference signal (No in S36), it repeats step S36.

[0055] When the voltage measuring device 40 receives the reference signal (Yes in S36), correction is started (S38). The correction method in the correction circuit 43 according to this embodiment will be described with reference to FIG.

[0056] Fig. 5 is a block diagram showing the functional configuration of the correction circuit 43 according to this embodiment. Fig. 5 also shows a mode control circuit 45 and a slave oscillator 46. As shown in Fig. 5, the correction circuit 43 has a pulse counter 81, an arithmetic circuit 82, and a memory circuit 83.

[0057] The pulse counter 81 is a circuit that receives a reference signal, counts the number of pulse signals included in the reference signal, and outputs the counted number of pulse signals to the arithmetic circuit 82.

[0058] The arithmetic circuit 82 is a circuit that calculates a correction difference value based on the number of pulse signals included in the reference signal and information corresponding to the pre-correction oscillation frequency of the slave oscillator 46. The arithmetic circuit 82 corrects the oscillation frequency of the slave oscillator 46 by outputting a signal corresponding to the correction difference value to the slave oscillator 46.

[0059] The memory circuit 83 is a circuit that stores information corresponding to the pre-correction oscillation frequency of the slave oscillator 46. The memory circuit 83 stores a so-called trimming value that corresponds to the pre-correction oscillation frequency of the slave oscillator 46. The trimming value is a correction value used to set the pre-correction oscillation frequency of the slave oscillator 46.

[0060] When correction is started in the correction circuit 43, the pulse counter 81 starts counting pulse signals included in the reference signal in response to a signal from the mode control circuit 45. The pulse counter 81 outputs the number of counted pulse signals to the calculation circuit 82.

[0061] Next, as shown in Fig. 3, the voltage measuring device 40 calculates a correction difference value (S40). In this embodiment, the arithmetic circuit 82 shown in Fig. 5 calculates the correction difference value from the number of pulse signals included in the reference signal and information corresponding to the oscillation frequency of the slave oscillator 46 before correction.

[0062] More specifically, the arithmetic circuit 82 determines, from the number of pulse signals included in the reference signal, the period corresponding to the reference signal and the number of master clock signals output from the master oscillator 36 within that period. For example, the arithmetic circuit 82 may store in advance the number of master clock signals output at which a pulse signal included in the reference signal is generated. This allows the arithmetic circuit 82 to determine the number of master clock signals output from the master oscillator 36 within the period corresponding to the reference signal, based on the number of pulse signals included in the reference signal.

[0063] The arithmetic circuit 82 further determines the number of first clock signals output from the slave oscillator 46 within the period corresponding to the reference signal from information corresponding to the oscillation frequency of the slave oscillator 46 before correction input from the memory circuit 83 (see graph (c) in Figure 4).

[0064] The calculation circuit 82 calculates the correction difference value by determining the difference between the number of master clock signals output from the master oscillator 36 and the number of first clock signals output from the slave oscillator 46 within the period corresponding to the reference signal, which is determined as described above.

[0065] Next, as shown in Fig. 3, voltage measuring device 40 determines whether there is a format error in the reference signal (S42). For example, if the reference signal is not a pulse signal train as shown in graph (b) of Fig. 4, or if the number of counted pulse signals is not within a predetermined range, arithmetic circuit 82 of correction circuit 43 determines that there is a format error in the reference signal.

[0066] If the voltage measuring device 40 determines that the reference signal has a format error (Yes in S42), it discards the calculated correction difference value and does not perform correction (S46). On the other hand, if the voltage measuring device 40 determines that the reference signal does not have a format error (No in S42), it performs correction using the calculated correction difference value (S44). In this embodiment, the arithmetic circuit 82 shown in FIG. 5 corrects the oscillation frequency of the slave oscillator 46 by transmitting a signal corresponding to the correction difference value to the slave oscillator 46. For example, the oscillation frequency of the slave oscillator 46 can be corrected by adjusting the time constant of a circuit included in the slave oscillator 46. Specifically, the time constant of the RC circuit can be adjusted by adjusting the resistance component of the RC circuit included in the slave oscillator 46. This allows the oscillation frequency of the slave oscillator 46 to be corrected. Note that in the memory circuit 83, the trimming value before correction is rewritten with a trimming value corresponding to the correction difference value used for correction.

[0067] Next, the voltage measuring device 40 switches from the correction mode to the normal mode (S48). Specifically, the communication circuit 44 transmits a command signal to the mode control circuit 45 to instruct the mode control circuit 45 to switch to the normal mode.

[0068] As described above, the correction circuit 43 of the voltage measuring device 40 counts the number of pulse signals included in the reference signal and corrects the oscillation frequency of the slave oscillator 46 based on this count. The correction circuit 43 corrects the oscillation frequency of the slave oscillator 46 based on a correction difference value calculated from the number of clocks of the master oscillator 36 corresponding to the number of pulse signals and the number of clocks of the slave oscillator 46 in the period corresponding to the reference signal. The oscillation frequency of the slave oscillator 56 of the voltage measuring device 50 can also be corrected in a similar manner.

[0069] [1-3.Effects] The effects of the voltage measurement system 10 according to this embodiment will be described with reference to Fig. 4, Fig. 6, and Fig. 7. Fig. 6 and Fig. 7 are diagrams showing measurement timings before and after correction in the voltage measurement system 10 according to this embodiment, respectively.

[0070] Graph (a) showing the timing of current measurement shown in Figures 6 and 7 corresponds to the timing of voltage measurement by the voltage measuring device 40, that is, the timing of measuring the current flowing through the battery cell 21. Graph (b) showing the timing of voltage measurement shown in Figures 6 and 7 corresponds to the timing of measuring the voltage of the battery cell 21 by the voltage measuring device 40. The positions of the upward arrows shown in Figures 6 and 7 indicate the timing of measurement.

[0071] As described above, in this embodiment, the voltage measuring device 40 measures the voltage at a period determined based on the first clock signal output by the slave oscillator 46, and the voltage measuring device 50 measures the voltage at a period determined based on the second clock signal output by the slave oscillator 56. For example, the voltage is measured every time 1000 clocks of each of the first clock signal and the second clock signal are output.

[0072] Therefore, as shown in graphs (c) and (d) of FIG. 4, when the oscillation frequency of the slave oscillator 46 does not match the oscillation frequency of the slave oscillator 56, the current measurement cycle and the voltage measurement cycle will differ, as shown in FIG. 6. Therefore, even if the current measurement timing and the voltage measurement timing are approximately the same at the start of measurement, the difference between these timings will gradually increase. As a result, it is not possible to accurately grasp the state of the battery cell.

[0073] On the other hand, by correcting the oscillation frequencies of the slave oscillators 46 and 56 to match the oscillation frequency of the master oscillator 36, the measurement timing of each voltage measurement device can be controlled with high precision. In this case, the current measurement cycle and the voltage measurement cycle can be matched, as shown in FIG. 7. Therefore, the current measurement timing and the voltage measurement timing can be almost matched. Therefore, the state of the battery cell can be grasped with high precision.

[0074] Furthermore, in the voltage measurement system 10 according to this embodiment, not only the command signal but also the reference signal is transmitted and received using a daisy-chain communication path, eliminating the need to provide a new communication path for transmitting and receiving the reference signal. Furthermore, by using the daisy-chain communication path, corrections can be simultaneously performed in parallel for each voltage measurement device using a single command output from the communication device 30, allowing for simple and rapid correction. Furthermore, the voltage measurement system 10 according to this embodiment has a normal mode and a correction mode, and transmits and receives command signals or reference signals according to each mode, thereby preventing collisions between these signals.

[0075] (Embodiment 2) A voltage measurement system according to embodiment 2 will be described. The voltage measurement system according to this embodiment differs from voltage measurement system 10 according to embodiment 1 in that the voltage measurement device has a high-precision oscillator and corrects the oscillation frequency of the master oscillator in accordance with the high-precision oscillator. The voltage measurement system according to this embodiment will be described below, focusing on the differences from voltage measurement system 10 according to embodiment 1.

[0076] [2-1. Overall composition] The overall configuration of a voltage measurement system according to this embodiment will be described with reference to Fig. 8. Fig. 8 is a block diagram showing the functional configuration of a voltage measurement system 110 according to this embodiment. Fig. 8 also shows a battery cell 21, which is the object of measurement by the voltage measurement system 110, a resistive element 22, and a control device 20 that controls the voltage measurement system 110.

[0077] As shown in FIG. 8, the voltage measurement system 110 includes a communication device 130 and voltage measurement devices 140 and 50.

[0078] The voltage measuring device 140 of this embodiment has a selection circuit 41, a multiplexer 42, a reference signal correction circuit 143, a communication circuit 44, a mode control circuit 45, a high-precision oscillator 146, a measurement control circuit 47, and a voltage measuring circuit 48.

[0079] The high precision oscillator 146 is an oscillator that generates a high precision clock signal that is more accurate than the master oscillator 36. The high precision clock signal generated by the high precision oscillator 146 is transmitted to the reference signal correction circuit 143, the communication circuit 44, and the measurement control circuit 47. Note that the high precision oscillator 146 does not have to be included as a component of the voltage measurement device 140. For example, the high precision oscillator 146 may transmit a clock signal to the voltage measurement device 140 from outside the voltage measurement device 140.

[0080] The reference signal correction circuit 143 is a circuit that calculates a correction difference value for correcting the reference signal. Similar to the correction circuit 43 according to the first embodiment, the reference signal correction circuit 143 calculates a correction difference value between the high-precision clock signal and the master clock signal. The reference signal correction circuit 143 transmits the calculated correction difference value to the communication device 130 via the communication circuit 34 and the selection circuit 41.

[0081] The communication device 130 includes a communication circuit 34 , a master oscillator 36 , a reference signal generating circuit 33 , a mode control circuit 35 , a multiplexer 32 , and a master correction circuit 139 .

[0082] The master correction circuit 139 is a circuit that corrects the oscillation frequency of the master oscillator 36 based on the high-precision clock signal. The master correction circuit 139 corrects the oscillation frequency of the master oscillator 36 by outputting a signal corresponding to the correction difference value calculated by the reference signal correction circuit 143 of the voltage measurement device 140 to the master oscillator 36. The correction of the oscillation frequency of the master oscillator 36 can be performed in the same way as the correction of the oscillation frequency of the slave oscillator 46 according to the first embodiment.

[0083] [2-2. Correction method] A method for correcting the oscillation frequencies of the master oscillator 36 and the slave oscillator 56 in the voltage measurement system 110 according to this embodiment will be described.

[0084] First, the master oscillator 36 is corrected. Specifically, similar to the correction method according to the first embodiment, the communication device 130 switches to a correction mode and transmits a reference signal.

[0085] Next, the reference signal correction circuit 143 of the voltage measuring device 140 calculates the correction difference value and transmits it to the communication circuit 44, in the same manner as in the correction method according to the first embodiment.

[0086] Next, the communication circuit 44 of the voltage measuring device 140 transmits a signal corresponding to the correction difference value to the communication device 130 via the selection circuit 41.

[0087] Subsequently, the communication circuit 34 of the communication device 130 receives a signal corresponding to the correction difference value via the multiplexer 32 and transmits it to the master correction circuit 139 .

[0088] Subsequently, the master correction circuit 139 corrects the oscillation frequency of the master oscillator 36 by outputting a signal corresponding to the correction difference value to the master oscillator 36 .

[0089] As described above, the oscillation frequency of the master oscillator 36 can be corrected to match that of the high-precision oscillator 146.

[0090] Thereafter, the oscillation frequency of the slave oscillator 56 is corrected in the same manner as in the first embodiment.

[0091] This allows the oscillation frequency of slave oscillator 56 to match the oscillation frequency of high-precision oscillator 146. Therefore, the voltage measurement system 110 according to this embodiment also achieves the same effects as the voltage measurement system 10 according to the first embodiment. Furthermore, in this embodiment, the oscillation frequency of master oscillator 36 can be corrected, so the measurement timing of each voltage measurement device can be controlled with even greater precision.

[0092] (Embodiment 3) A voltage measurement system according to embodiment 3 will be described. The voltage measurement system according to this embodiment differs from voltage measurement system 10 according to embodiment 1 mainly in that it includes two communication devices. The voltage measurement system according to this embodiment will be described below, focusing on the differences from voltage measurement system 10 according to embodiment 1.

[0093] [3-1. Overall composition] The overall configuration of a voltage measurement system according to this embodiment will be described with reference to Fig. 9. Fig. 9 is a block diagram showing the functional configuration of a voltage measurement system 210 according to this embodiment. Fig. 9 also shows a battery cell 21, which is the object of measurement by the voltage measurement system 210, a resistive element 22, and a control device 220 that controls the voltage measurement system 210.

[0094] 9, voltage measurement system 210 includes communication devices 230 and 230a and voltage measurement devices 40 and 50. In this embodiment, signals are transmitted and received between control device 220, communication device 230, and voltage measurement device 40 using a daisy chain communication path, and signals are transmitted and received between control device 220, communication device 230a, and voltage measurement device 50 using a daisy chain communication path.

[0095] The control device 220 includes a communication circuit 221 and a control oscillator 222 .

[0096] The communication circuit 221 is a circuit for transmitting and receiving command signals to and from the communication devices 230 and 230a.

[0097] The control oscillator 222 is an oscillator that generates a control clock signal.

[0098] The communication device 230 is an example of a first reference signal transmission device that receives a control clock signal, which is an externally input clock signal, and transmits a reference signal. The communication device 230 includes a communication circuit 34, a master oscillator 36, a reference signal generation circuit 33, a mode control circuit 35, a multiplexer 32, and a master correction circuit 239.

[0099] The master correction circuit 239 is an example of a first master correction circuit that corrects the oscillation frequency of the master oscillator 36 based on a control clock signal. The control clock signal is input to the master correction circuit 239. The master correction circuit 239 may, for example, count the number of control clock signals within a predetermined time, calculate a correction difference value from this count and the number of master clock signals of the master oscillator 36 within the predetermined time, and correct the oscillation frequency of the master oscillator 36 based on this correction difference value.

[0100] The communication device 230a is an example of a second reference signal transmission device that receives a control clock signal, which is a clock signal input from an external device, and transmits a reference signal. The communication device 230a transmits and receives command signals to the voltage measurement device 50 and transmits a reference signal to the voltage measurement device 50. The communication device 230a includes a communication circuit 34a, a master oscillator 36a, a reference signal generation circuit 33a, a mode control circuit 35a, a multiplexer 32a, and a master correction circuit 239a. The communication circuit 34a, the master oscillator 36a, the reference signal generation circuit 33a, the mode control circuit 35a, the multiplexer 32a, and the master correction circuit 239a have the same configurations as the communication circuit 34, the master oscillator 36a, the reference signal generation circuit 33, the mode control circuit 35, the multiplexer 32, and the master correction circuit 239, respectively.

[0101] The master oscillator 36a is an example of a second master oscillator that generates a master clock signal. The master clock signal generated by the master oscillator 36a is an example of a second master clock signal.

[0102] The reference signal generating circuit 33a is an example of a second reference signal generating circuit that generates a reference signal based on the master clock signal generated by the master oscillator 36a. The reference signal generated by the reference signal generating circuit 33a is an example of a second reference signal that is generated based on the master clock signal generated by the master oscillator 36a.

[0103] The master correction circuit 239a is an example of a second master correction circuit that corrects the oscillation frequency of the master oscillator 36a based on the control clock signal.

[0104] [3-2. Correction method] A method for correcting the oscillation frequencies of the master oscillators 36, 36a and the slave oscillators 46, 56 in the voltage measurement system 210 according to this embodiment will be described.

[0105] First, the master oscillators 36 and 36a are corrected. Specifically, the communication devices 230 and 230a switch to a correction mode based on a command signal from the control device 220.

[0106] Subsequently, the master correction circuit 239 calculates the correction difference value in the above-described manner based on the control clock signal input from the control device 220. The master correction circuit 239a also calculates the correction difference value in the same manner.

[0107] Subsequently, the master correction circuit 239 corrects the oscillation frequency of the master oscillator 36 by inputting a signal corresponding to the correction difference value to the master oscillator 36. The master correction circuit 239a similarly corrects the oscillation frequency of the master oscillator 36a.

[0108] As described above, the oscillation frequencies of the master oscillators 36, 36a can be corrected based on the control clock signal.

[0109] Thereafter, the oscillation frequencies of the slave oscillators 46 and 56 are corrected in the same manner as in the first embodiment.

[0110] This allows the oscillation frequencies of the master oscillators 36, 36a and the slave oscillators 46, 56 to match the oscillation frequency of the control oscillator 222. Therefore, the voltage measurement system 210 according to this embodiment also achieves the same effects as the voltage measurement system 10 according to the first embodiment.

[0111] (Fourth embodiment) A voltage measurement system according to embodiment 4 will be described. The voltage measurement system according to this embodiment differs from voltage measurement system 210 according to embodiment 3 mainly in that a reference signal transmitted from one of two communication devices is used to correct the oscillation frequency of a master oscillator in the other communication device. The voltage measurement system according to this embodiment will be described below, focusing on the differences from voltage measurement system 210 according to embodiment 3.

[0112] [4-1. Overall composition] The overall configuration of a voltage measurement system according to this embodiment will be described with reference to Fig. 10. Fig. 10 is a block diagram showing the functional configuration of a voltage measurement system 310 according to this embodiment. Fig. 10 also shows a battery cell 21, which is the object of measurement by the voltage measurement system 310, a resistive element 22, and a control device 20 that controls the voltage measurement system 310.

[0113] 10, voltage measurement system 310 includes communication devices 330 and 330a and voltage measurement devices 40 and 50. In this embodiment, signals are transmitted and received between control device 20, communication device 330, and voltage measurement device 40 using a daisy chain communication path, and signals are transmitted and received between control device 20, communication device 330a, and voltage measurement device 50 using a daisy chain communication path.

[0114] The communication device 330 is an example of a first reference signal transmission device that transmits a reference signal. The communication device 330 includes a communication circuit 34, a master oscillator 36, a reference signal generation circuit 33, a mode control circuit 35, and a multiplexer 32. The communication device 330 according to this embodiment differs from the communication device 30 according to the first embodiment in that it transmits a reference signal not only to the voltage measurement device 40 but also to the communication device 330a, but is the same in other respects.

[0115] The communication device 330a is an example of a second reference signal transmission device that transmits a reference signal, and includes a communication circuit 34a, a master oscillator 36a, a reference signal generation circuit 33a, a mode control circuit 35a, a multiplexer 32a, and a master correction circuit 339a.

[0116] The master correction circuit 339a is an example of a second master correction circuit that corrects the oscillation frequency of the master oscillator 36a based on the master clock signal generated by the master oscillator 36 of the communication device 330. The master correction circuit 339a receives a reference signal from the communication device 330. The master correction circuit 339a has a configuration similar to that of the correction circuit 43 according to the first embodiment, and corrects the oscillation frequency of the master oscillator 36a based on the reference signal.

[0117] [4-2. Correction method] A method for correcting the oscillation frequencies of the master oscillator 36a and the slave oscillators 46 and 56 in the voltage measurement system 310 according to this embodiment will be described.

[0118] First, the master oscillator 36a is corrected. Specifically, the communication devices 330 and 330a switch to the correction mode based on a command signal from the control device 20.

[0119] Next, the communication device 330 transmits to the master correction circuit 339a of the communication device 330a a reference signal generated in the same manner as the reference signal according to Embodiment 1. The master correction circuit 339a calculates a correction difference value based on the received reference signal.

[0120] Subsequently, the master correction circuit 339a corrects the oscillation frequency of the master oscillator 36a by inputting a signal corresponding to the correction difference value to the master oscillator 36a.

[0121] As described above, the oscillation frequency of the master oscillator 36a of the communication device 330a can be corrected based on the master clock signal of the master oscillator 36 of the communication device 330a.

[0122] Thereafter, the oscillation frequencies of the slave oscillators 46 and 56 are corrected in the same manner as in the first embodiment.

[0123] This allows the oscillation frequencies of the master oscillator 36a and the slave oscillators 46 and 56 to match the oscillation frequency of the master oscillator 36. Therefore, the voltage measurement system 310 according to this embodiment also achieves the same effects as the voltage measurement system 210 according to the third embodiment.

[0124] (Embodiment 5) A voltage measurement system according to embodiment 5 will be described. The voltage measurement system according to this embodiment differs from voltage measurement system 10 according to embodiment 1 mainly in that a voltage measurement device generates a reference signal. The voltage measurement system according to this embodiment will be described below, focusing on the differences from voltage measurement system 10 according to embodiment 1.

[0125] [5-1. Overall composition] The overall configuration of a voltage measurement system according to this embodiment will be described with reference to Fig. 11. Fig. 11 is a block diagram showing the functional configuration of a voltage measurement system 410 according to this embodiment. Fig. 11 also shows a battery cell 21, which is the object of measurement by the voltage measurement system 410, a resistive element 22, and a control device 20 that controls the voltage measurement system 410.

[0126] 11, a voltage measurement system 410 includes voltage measurement devices 440 and 50. In this embodiment, signals are transmitted and received between the control device 20, the voltage measurement device 440, and the voltage measurement device 50 using a daisy chain communication path.

[0127] The voltage measurement device 440 is an example of a first reference signal transmission device that transmits a reference signal. The voltage measurement device 440 includes a multiplexer 42, a reference signal generation circuit 443, a communication circuit 444, a mode control circuit 45, a master oscillator 446, a measurement control circuit 447, and a voltage measurement circuit 48.

[0128] The communication circuit 444 is a circuit that transmits and receives command signals between the control device 20 and the voltage measuring device 50. For example, when the communication circuit 444 receives a command signal from the control device 20 instructing the start of voltage measurement, the communication circuit 444 transmits the command signal (or a signal corresponding to the command signal) to the measurement control circuit 447 and the voltage measuring device 50. Furthermore, when the communication circuit 444 receives a command signal from the control device 20 instructing the switching to the normal mode or the correction mode, the communication circuit 444 transmits the command signal (or a signal corresponding to the command signal) to the voltage measuring device 50. Furthermore, when the communication circuit 444 receives a command signal instructing the switching to the correction mode, the communication circuit 444 transmits a signal instructing the reference signal generating circuit 443 to generate a reference signal.

[0129] The master oscillator 446 is an example of a first master oscillator that generates a master clock signal. The master clock signal is an example of a first master clock signal used to generate a reference signal. The master clock signal generated by the master oscillator 446 is transmitted to the reference signal generation circuit 443, the communication circuit 444, and the measurement control circuit 447.

[0130] The reference signal generation circuit 443 is an example of a first reference signal generation circuit that generates a reference signal based on a master clock signal in the correction mode. The reference signal generation circuit 443 generates a reference signal based on a command signal received from the communication circuit 444. The reference signal is an example of a first reference signal that is generated based on a master clock signal.

[0131] Measurement control circuit 447 is a circuit that controls voltage measurement circuit 48 based on a master clock signal. Measurement control circuit 447 has the same configuration as measurement control circuit 47 according to the first embodiment.

[0132] The voltage measurement device 50 according to this embodiment is an example of a first voltage measurement device that corrects the oscillation frequency of the slave oscillator 56 based on the reference signal received from the voltage measurement device 440 .

[0133] [5-2. Correction method] A method for correcting the oscillation frequency of the slave oscillator 56 in the voltage measurement system 410 according to this embodiment will be described.

[0134] The voltage measuring device 440 switches to the correction mode based on a command signal from the control device 20 .

[0135] Next, similarly to the communication device 30 according to the first embodiment, the reference signal generating circuit 443 of the voltage measuring device 440 generates a reference signal and transmits it to the voltage measuring device 50.

[0136] Next, the voltage measuring device 50 corrects the oscillation frequency of the slave oscillator 56 based on the reference signal, similar to the voltage measuring device 50 according to the first embodiment.

[0137] This allows the oscillation frequency of the slave oscillator 56 to match the oscillation frequency of the master oscillator 446. Therefore, the voltage measurement system 410 according to this embodiment also achieves the same effects as the voltage measurement system 10 according to the first embodiment. Furthermore, in this embodiment, the communication device can be omitted, thereby simplifying the configuration.

[0138] (Embodiment 6) A voltage measurement system according to a sixth embodiment will be described. The voltage measurement system according to this embodiment differs from the voltage measurement system 10 according to the first embodiment mainly in that the voltage measurement system according to this embodiment uses a first clock signal generated by the corrected slave oscillator to correct an oscillator that is slower than the slave oscillator. The following describes the voltage measurement system according to this embodiment, focusing on the differences from the voltage measurement system 10 according to the first embodiment.

[0139] [6-1. Overall composition] The overall configuration of a voltage measurement system according to this embodiment will be described with reference to Fig. 12. Fig. 12 is a block diagram showing the functional configuration of a voltage measurement system 510 according to this embodiment. Fig. 12 also shows a battery cell 21, which is the object of measurement by the voltage measurement system 510, a resistive element 22, and a control device 20 that controls the voltage measurement system 510.

[0140] As shown in FIG. 12, the voltage measurement system 510 includes a communication device 30 and voltage measurement devices 540 and 550.

[0141] The voltage measurement device 540 includes a selection circuit 41, a multiplexer 42, a correction circuit 43, a communication circuit 544, a mode control circuit 45, a slave oscillator 46, a measurement control circuit 47, a voltage measurement circuit 48, a low-speed correction circuit 549, and a low-speed oscillator 546.

[0142] The low-speed oscillator 546 generates a low-speed clock signal and is an example of a first low-speed oscillator having a lower oscillation frequency than the slave oscillator 46. The low-speed oscillator 546 may be used to control the timing of any operation in the voltage measurement device 540. The low-speed oscillator 546 may be used, for example, to control the timing of balancing between multiple battery cells.

[0143] The low-speed correction circuit 549 is an example of a first low-speed correction circuit that corrects the oscillation frequency of the low-speed oscillator 546 based on the first clock signal from the slave oscillator 46. The low-speed correction circuit 549 corrects the oscillation frequency of the low-speed oscillator 546, for example, in the correction mode. The low-speed correction circuit 549 may correct the oscillation frequency of the low-speed oscillator 546 so that the number of clocks of the first clock signal output from the slave oscillator 46 becomes a predetermined number within a period corresponding to one pulse of the low-speed clock signal output from the low-speed oscillator 546.

[0144] The low-speed correction circuit 549 may also correct the oscillation frequency of the low-speed oscillator 546 based on the first clock signal from the slave oscillator 46 that has been corrected based on the reference signal.

[0145] The communication circuit 544 differs from the communication circuit 44 of embodiment 1 in that, when it receives a command signal instructing correction of the low-speed oscillator 546, it transmits the command signal (or a signal corresponding to the command signal) to the low-speed correction circuit 549, but is the same in other respects.

[0146] The voltage measurement device 550 includes a selection circuit 51, a multiplexer 52, a correction circuit 53, a communication circuit 554, a mode control circuit 55, a slave oscillator 56, a measurement control circuit 57, a voltage measurement circuit 58, a low-speed correction circuit 559, and a low-speed oscillator 556. The communication circuit 554, the low-speed correction circuit 559, and the low-speed oscillator 556 have configurations similar to the communication circuit 544, the low-speed correction circuit 549, and the low-speed oscillator 546 of the voltage measurement device 540, respectively. The low-speed oscillator 556 is an example of a second low-speed oscillator that generates a low-speed clock signal and has a lower oscillation frequency than the slave oscillator 56. The low-speed correction circuit 559 is an example of a second low-speed correction circuit that corrects the oscillation frequency of the low-speed oscillator 556 based on the second clock signal from the slave oscillator 56.

[0147] [6-2. Correction method] The following describes a method for correcting the slave oscillators 46, 56 and the low-speed oscillators 546, 556 according to this embodiment. The method for correcting the slave oscillators 46, 56 according to this embodiment is the same as the method for correcting the slave oscillators 46, 56 according to the first embodiment.

[0148] For example, the low-speed correction circuits 549 and 559 correct the low-speed oscillators 546 and 556, respectively, during the period when the pulse counter 81 (see FIG. 5) counts pulses in the correction mode. This allows correction of not only the slave oscillators 46 and 56, but also the low-speed oscillators 546 and 556.

[0149] Furthermore, in the correction mode, the low-speed correction circuits 549, 559 may correct the low-speed oscillators 546, 556 after correcting the slave oscillators 46, 56. This allows for highly accurate control of not only the timing of voltage measurement in the voltage measurement device 540 but also the timing of other operations.

[0150] (Variations, etc.) Although the present disclosure has been described above based on the embodiments, the present disclosure is not limited to the above embodiments.

[0151] For example, in each of the above embodiments, the control device is not included in the voltage measurement system, but it may be included in the voltage measurement system.

[0152] Furthermore, the voltage measurement system according to each of the above embodiments may be housed in a single housing, or may be separated into multiple housings.

[0153] Furthermore, some or all of the components constituting the voltage measurement system according to each of the above embodiments may be configured as a single system LSI (Large Scale Integration). A system LSI is an ultra-multifunctional LSI manufactured by integrating multiple components on a single chip, and specifically, is a computer system configured to include a microprocessor, ROM, RAM, etc. A computer program is stored in the RAM. The system LSI achieves its functions when the microprocessor operates in accordance with the computer program.

[0154] Furthermore, some or all of the components constituting the voltage measurement system according to each of the above embodiments may be configured as a removable IC card or a standalone module. The IC card or module is a computer system configured with a microprocessor, ROM, RAM, etc. The IC card or module may include the above-mentioned ultra-multifunctional LSI. The IC card or module achieves its functions when the microprocessor operates according to a computer program. The IC card or module may be tamper-resistant.

[0155] The present disclosure may also be a computer system having a microprocessor and a memory, the memory storing the computer program, and the microprocessor operating in accordance with the computer program.

[0156] This disclosure also includes forms obtained by applying various modifications to the above-mentioned embodiments that a person skilled in the art would conceive, and forms realized by arbitrarily combining the components and functions of the above-mentioned embodiments within the scope of the present disclosure. [Industrial Applicability]

[0157] A voltage measurement system according to the present disclosure can be used, for example, as a voltage measurement system for an in-vehicle battery module system. [Explanation of symbols]

[0158] 10, 110, 210, 310, 410, 510 Voltage Measurement System 20, 220 control device 21 battery cells 22 Resistive element 30, 130, 230, 230a, 330, 330a communication equipment 32, 32a, 42, 52 multiplexers 33, 33a, 443 Reference signal generation circuit 34, 34a, 44, 54, 221, 444, 544, 554 Communication circuits 35, 35a, 45, 55 Mode control circuit 36, 36a, 446 Master Oscillator 40, 50, 140, 440, 540, 550 voltage measuring device 41, 51 Selection circuit 43, 53 Correction circuit 46, 56 Slave oscillator 47, 57, 447 Measurement control circuit 48, 58 Voltage measurement circuit 81 Pulse Counter 82 Arithmetic circuit 83 Memory circuit 139, 239, 239a, 339a Master correction circuit 143 Reference signal correction circuit 146 High-Precision Oscillator 222 Control Oscillator 546, 556 slow oscillator 549, 559 Low speed correction circuit

Claims

1. A voltage measurement system for measuring a voltage of a battery cell, comprising: a first reference signal transmitting device having a first master oscillator that generates a first master clock signal and a first reference signal generating circuit that generates a first reference signal based on the first master clock signal; a first voltage measurement device including a first slave oscillator that generates a first clock signal, a first correction circuit that corrects an oscillation frequency of the first slave oscillator based on the first reference signal, a first voltage measurement circuit, and a first measurement control circuit that controls the first voltage measurement circuit based on the first clock signal; The voltage measurement system includes: a normal mode in which a command signal is transmitted and received between the first reference signal transmitting device and the first voltage measuring device; a correction mode in which the first reference signal is transmitted from the first reference signal transmitting device to the first voltage measuring device, and the oscillation frequency of the first slave oscillator is synchronized with the oscillation frequency of the first master oscillator using the first reference signal; the first reference signal transmitter includes a communication circuit for transmitting and receiving the command signal; a multiplexer for transmitting and receiving the command signal and the first reference signal; The multiplexer transmits and receives the command signal in the normal mode and transmits and receives the first reference signal in the correction mode. Voltage measurement system.

2. the first voltage measuring device includes a first communication circuit for transmitting and receiving a command signal; a first multiplexer that transmits and receives the command signal and the first reference signal; The first multiplexer transmits and receives the command signal in the normal mode and transmits and receives the first reference signal in the correction mode. The voltage measurement system of claim 1 .

3. the first voltage measurement device further includes a first selection circuit that transmits and receives the command signal and the first reference signal; The first selection circuit transmits and receives the command signal to and from the first communication circuit in the normal mode, and receives the first reference signal and transmits the first reference signal to the first correction circuit and the first multiplexer in the correction mode. The voltage measurement system of claim 2 .

4. In the correction mode, the first multiplexer transmits the first reference signal to other devices in the voltage measurement system.

4. The voltage measurement system according to claim 2 or 3.

5. The first measurement control circuit controls the first voltage measurement circuit to measure a voltage at a period determined based on the first clock signal. The voltage measurement system according to any one of claims 1 to 4.

6. The first correction circuit counts the number of pulse signals included in the first reference signal and corrects the oscillation frequency of the first slave oscillator based on the count. The voltage measurement system according to any one of claims 1 to 5.

7. The first correction circuit corrects the oscillation frequency of the first slave oscillator based on a correction difference value calculated from the number of clocks of the first master oscillator corresponding to the number of pulse signals and the number of clocks of the first slave oscillator in a period corresponding to the first reference signal. The voltage measurement system of claim 6 .

8. The first correction circuit does not correct the oscillation frequency of the first slave oscillator when the counted number is not within a predetermined range.

8. The voltage measurement system according to claim 6 or 7.

9. The first voltage measurement device is a first low-speed oscillator having an oscillation frequency lower than that of the first slave oscillator; a first low-speed correction circuit that corrects the oscillation frequency of the first low-speed oscillator based on the first clock signal from the first slave oscillator. The voltage measurement system according to any one of claims 1 to 8.

10. The first low-speed correction circuit corrects the oscillation frequency of the first low-speed oscillator based on the first clock signal from the first slave oscillator, which has been corrected based on the first reference signal. The voltage measurement system of claim 9 .

11. a second voltage measurement device that receives the first reference signal via the first voltage measurement device; The second voltage measuring device is a second slave oscillator generating a second clock signal; a second correction circuit that corrects the oscillation frequency of the second slave oscillator based on the first reference signal; a second voltage measurement circuit; a second measurement control circuit that controls the second voltage measurement circuit based on the second clock signal; The voltage measurement system according to any one of claims 1 to 10.

12. the first reference signal transmitting device, a voltage measurement circuit; a measurement control circuit that controls the voltage measurement circuit based on the first master clock signal; The voltage measurement system according to any one of claims 1 to 11.

13. further comprising a high precision oscillator that generates a high precision clock signal that is more accurate than the first master oscillator; The first reference signal transmission device further includes a first master correction circuit that corrects the oscillation frequency of the first master oscillator based on the high-precision clock signal. The voltage measurement system according to any one of claims 1 to 11.

14. a second reference signal transmitting device having a second master oscillator that generates a second master clock signal and a second reference signal generating circuit that generates a second reference signal based on the second master clock signal; each of the first reference signal transmission device and the second reference signal transmission device receives a control clock signal that is an externally input clock signal; the first reference signal transmission device further includes a first master correction circuit that corrects an oscillation frequency of the first master oscillator based on the control clock signal; The second reference signal transmission device further includes a second master correction circuit that corrects the oscillation frequency of the second master oscillator based on the control clock signal. The voltage measurement system according to any one of claims 1 to 11.

15. a second reference signal transmitting device having a second master oscillator that generates a second master clock signal and a second reference signal generating circuit that generates a second reference signal based on the second master clock signal; The second reference signal transmitting device further includes a second master correction circuit that corrects the oscillation frequency of the second master oscillator based on the first master clock signal. The voltage measurement system according to any one of claims 1 to 11.

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