Battery monitoring device, integrated circuit, and battery monitoring system

Abstract

The battery monitoring device (100) includes a first reference resistor (103) arranged on a path (P2) separate from a path (P1) of a current flowing from the battery to a load (102), a transistor (104) for passing a current from the battery to the first reference resistor (103), and an integrated circuit (105). The integrated circuit (105) includes a current measurement unit (112) that measures a first current flowing through the first reference resistor (103), a voltage measurement unit (115) that measures the voltage of a battery (B), and a first calculation unit (118) that calculates the AC impedance of the battery based on the measured first current and the measured first voltage.

Description

Technical Field

[0001] The present disclosure relates to a battery monitoring device for monitoring the state of a battery.

Background Art

[0002] The development of automobiles that run using a secondary battery as a power source, such as HEV (Hybrid Electric Vehicle) or EV (Electric Vehicle), is underway. In addition, techniques for estimating the remaining battery capacity and detecting abnormalities by a battery management system (BMS: Battery Management System) in order to safely use the secondary battery are known. As such a BMS, Patent Document 1 discloses a battery monitoring device that can monitor the state of a battery in real time.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a battery monitoring device, an integrated circuit, and a battery monitoring system that can measure the AC impedance of a battery regardless of whether the battery is charging or discharging.

Means for Solving the Problems

[0005] A battery monitoring device according to one aspect of the present disclosure includes a resistor disposed on a path different from the path of the current flowing from the battery to the load, a transistor for flowing a current from the battery to the resistor, and an integrated circuit. The integrated circuit includes a current measurement unit that measures a first current flowing through the resistor, a voltage measurement unit that measures a first voltage of the battery, and a first calculation unit that calculates an AC impedance of the battery based on the measured first current and the measured first voltage.

[0006] An integrated circuit according to one aspect of the present disclosure includes a signal application unit that applies a control signal to a control terminal of a transistor for flowing a current from a battery to a resistor disposed on a path different from the path of the current flowing from the battery to the load, a current measurement unit that measures a first current flowing through the resistor, a voltage measurement unit that measures a first voltage of the battery, and a first calculation unit that calculates an AC impedance of the battery based on the measured first current and the measured first voltage.

[0007] A battery monitoring system according to one aspect of the present disclosure includes a plurality of the battery monitoring devices, and an integrated control unit that acquires the AC impedance from each of the plurality of battery monitoring devices.

[0008] A battery monitoring system according to one aspect of the present disclosure includes the battery monitoring device and a server device disposed at a location separated from the battery monitoring device. The server device acquires the AC impedance from the battery monitoring device.

Advantages of the Invention

[0009] According to one aspect of the present disclosure, a battery monitoring device, an integrated circuit, and a battery monitoring system capable of measuring the AC impedance of a battery regardless of whether the battery is being charged or discharged are realized.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

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Figure 5

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Figure 7

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Figure 10

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Figure 12

DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described with reference to the drawings. Note that each of the embodiments described below shows comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, steps, order of steps, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. In addition, among the components in the following embodiments, the components not described in the independent claims are described as optional components.

[0012] Note that each figure is a schematic diagram and is not necessarily drawn precisely. Also, in each figure, substantially the same components are denoted by the same reference numerals, and duplicate descriptions may be omitted or simplified.

[0013] (Embodiment 1) [Configuration] First, the configuration of the battery monitoring device according to Embodiment 1 will be described. FIG. 1 is a block diagram showing the functional configuration of the battery monitoring device according to Embodiment 1.

[0014] The battery monitoring device 100 shown in FIG. 1 is a device that monitors the state of the battery pack 101. The battery pack 101 includes a plurality of batteries B0 to B7 (hereinafter, any one of the batteries B0 to B7 is referred to as battery B). Battery B is, in other words, a battery cell. Specifically, battery B is a lithium-ion battery, but it may be other batteries such as nickel-metal hydride batteries. The battery pack 101 functions as a power source for the load 102 and supplies power to the load 102. The load 102 is, for example, an EV motor, but is not particularly limited. Note that instead of the load 102, a charging device for charging the battery pack 101 may be connected at the position of the load 102.

[0015] Specifically, the battery monitoring device 100 can calculate and monitor the AC impedance of the battery B. FIG. 2 is a diagram showing the equivalent circuit of the battery B.

[0016] As shown in FIG. 2, the battery B can be considered to have a circuit configuration in which a resistor R0, a resistor R1 and a capacitor C1 connected in parallel, a resistor R2 and a capacitor C2 connected in parallel... are connected in series. The circuit parameters (resistance value of the resistor or capacitance value of the capacitor) in this circuit configuration change as the battery B deteriorates. That is, the AC impedance of the battery B changes as the battery B deteriorates. FIG. 3 is a diagram showing the relationship between the change in the AC impedance of the battery B and the deterioration of the battery B. FIG. 3 is a diagram called a Cole-Cole plot and is also called a Nyquist plot.

[0017] The AC impedance of battery B has the initial characteristics shown by the solid line in FIG. 3. When the electrode performance of battery B deteriorates, the AC impedance of battery B changes to the characteristics shown by the broken line in FIG. 3. Also, when the electrolyte performance of battery B deteriorates, the AC impedance of battery B changes to the characteristics shown by the dashed-dotted line in FIG. 3.

[0018] Thus, there is a correlation between the degree of deterioration of battery B and the AC impedance of battery B, and the battery monitoring device 100 can determine the degree of deterioration of battery B by calculating and monitoring the AC impedance of battery B. Once the degree of deterioration is determined, information processing such as presenting a message prompting replacement of the deteriorated battery B becomes possible. Note that the degree of deterioration of battery B is expressed by a parameter called SOH (State of Health), for example.

[0019] As shown in FIG. 1 above, in the battery monitoring device 100, the AC impedance is measured using a first reference resistor 103 arranged on a path P2 (in other words, the second path), which is different from the path P1 (in other words, the first path) of the current flowing from the battery pack 101 to the load 102. Thereby, the battery monitoring device 100 can calculate the AC impedance of battery B regardless of whether battery B is being charged or discharged. For example, the battery monitoring device 100 can calculate the current AC impedance of battery B in parallel with the charging during charging of battery B. Also, the battery monitoring device 100 can calculate the current AC impedance of battery B in parallel with the discharging during discharging of battery B. The battery monitoring device 100 can calculate the current AC impedance of battery B during the stop of charging and discharging of the battery.

[0020] Hereinafter, the specific configuration of such a battery monitoring device 100 will be described with reference to FIG. 1 above. The battery monitoring device 100 includes a first reference resistor 103, a transistor 104, an integrated circuit (battery monitoring circuit) 105, a load resistor 106, a temperature sensor 107, and a heater 108.

[0021] The first reference resistor 103 is a resistor disposed on a path P2 different from the path P1 of the current flowing from the battery pack 101 to the load 102. That is, the first reference resistor 103 is a resistor through which the current flowing to the load 102 does not flow. The first reference resistor 103 is, for example, a discrete component provided outside the integrated circuit 105.

[0022] The transistor 104 is a transistor for flowing a current from the battery pack 101 to the first reference resistor 103. The transistor 104 is, for example, an FET (Field Effect Transistor), but may be a bipolar transistor. The drain of the transistor 104 is connected to the load resistor 106, the source of the transistor 104 is connected to the first reference resistor 103, and the gate (i.e., the control terminal) of the transistor 104 is connected to the signal application unit 109.

[0023] The integrated circuit 105 includes a signal application unit 109, a current measurement unit 112, a voltage measurement unit 115, a reference bias generation unit 116, a timing signal generation unit 117, a first calculation unit 118, a second calculation unit 119, a first temperature measurement unit 120, a second temperature measurement unit 121, a first temperature control unit 122, a load current measurement unit 123, a third temperature measurement unit 127, a second temperature control unit 129, and a communication interface unit 131.

[0024] The signal application unit 109 applies a control signal to the control terminal of the transistor 104. The signal application unit 109 includes a signal generation unit 110 and a waveform generation unit 111.

[0025] The current measurement unit 112 measures the current Iac (an example of the first current) flowing through the first reference resistor 103. Specifically, the current measurement unit 112 measures the voltage across both ends of the first reference resistor 103. The first calculation unit 118 can recognize the voltage across both ends of the first reference resistor 103 as the current Iac based on the resistance value of the first reference resistor 103.

[0026] Specifically, the current measurement unit 112 includes an AD (Analog to Digital) converter 113 (denoted as ADC in the figure) that converts the voltage across both ends of the first reference resistor 103 (i.e., the analog signal) into a digital signal, and a filter 114 connected to the output of the AD converter 113. The AD converter 113 is, for example, a delta-sigma type AD converter, and the filter 114 is a decimation filter. The AD converter 113 uses, for example, an AD converter having the same AD conversion characteristics as the plurality of AD converters 0 to 7 (i.e., the same as a product). Thereby, it is possible to reduce the measurement error caused by AD conversion that occurs between the AD converters 0 to 7 and the AD converter 113.

[0027] The voltage measurement unit 115 measures the voltages V0 to V7 (an example of the first voltage) of the plurality of batteries B0 to B7 that make up the battery pack 101. The voltage measurement unit 115 includes AD converters 0 to 7 that convert the voltages V0 to V7 of the plurality of batteries B0 to B7 into digital signals, and filters 0 to 7 connected to the outputs of the AD converters 0 to 7. Each of the AD converters 0 to 7 is, for example, a delta-sigma type AD converter, and each of the filters 0 to 7 is a decimation filter.

[0028] In the integrated circuit 105, the plurality of AD converters 0 to 7 have the same AD conversion characteristics. The AD conversion characteristics are various parameters such as resolution (number of bits). Specifically, the same AD converter as a product is used for the plurality of AD converters 0 to 7. Thereby, it is possible to reduce the measurement error caused by AD conversion that occurs between the voltages V0 to V7.

[0029] The reference bias generation unit 116 supplies a common reference voltage to the plurality of AD converters 0 to 7, the AD converter 113, and the AD converter 125. According to the reference bias generation unit 116, it is possible to reduce the error of AD conversion caused by variations in the reference voltage.

[0030] The timing signal generation unit 117 supplies a timing signal for synchronizing the measurement timings of the plurality of AD converters 0 to 7, the AD converter 113, and the AD converter 125 to each of the plurality of AD converters 0 to 7, the AD converter 113, and the AD converter 125. According to the timing signal generation unit 117, it becomes possible to measure the voltages V0 to V7, the current Iac, and the current Icd at the same timing.

[0031] The first calculation unit 118 calculates the AC impedance of the batteries B0 to B7 based on the current Iac measured by the current measurement unit 112 and the voltages V0 to V7 measured by the voltage measurement unit 115. In other words, the first calculation unit 118 is an AC impedance calculation unit. The specific configuration of the first calculation unit 118 will be described later.

[0032] The second calculation unit 119 calculates at least one of the SOC (State of Charge) and SOH of the batteries B0 to B7 using the AC impedance calculated by the first calculation unit 118. In other words, the second calculation unit 119 is an SOC / SOH calculation unit.

[0033] The first temperature measurement unit 120 measures the temperatures Tcell0 to Tcell7 of the plurality of batteries B0 to B7 using the temperature sensors S0 to S7 provided in a one-to-one correspondence with the plurality of batteries B0 to B7. The temperature sensors S0 to S7 are, for example, temperature sensors using thermistors, but may also be temperature sensors using other elements such as thermocouples.

[0034] The second temperature measurement unit 121 measures the temperature Tref1 of the first reference resistor 103 using the temperature sensor 107 provided in the vicinity of the first reference resistor 103. The temperature sensor 107 is, for example, a temperature sensor using a thermistor, but may also be a temperature sensor using other elements such as a thermocouple.

[0035] The first temperature control unit 122 controls the temperature of the first reference resistor 103 to be constant. Specifically, the first temperature control unit 122 acquires the temperature Tref1 of the first reference resistor 103 measured by the second temperature measurement unit 121, and controls the heater 108 so that the acquired temperature Tref1 becomes constant.

[0036] The load current measurement unit 123 measures the current Icd flowing through the load 102. Specifically, the load current measurement unit 123 measures the voltage across both ends of the second reference resistor 124. The first calculation unit 118 can recognize the voltage across both ends of the second reference resistor 124 as the current Icd based on the resistance value of the second reference resistor 124.

[0037] Specifically, the load current measurement unit 123 includes an AD converter 125 that converts the voltage across both ends of the second reference resistor 124 (that is, an analog signal) into a digital signal, and a filter 126 connected to the output of the AD converter 125. The AD converter 125 is, for example, a delta-sigma type AD converter, and the filter 126 is a decimation filter. For the AD converter 125, for example, an AD converter having the same AD conversion characteristics (that is, the same as a product) as the plurality of AD converters 0 to 7 is used. Thereby, the error caused by AD conversion that occurs between the AD converters 0 to 7 and the AD converter 125 can be reduced.

[0038] The third temperature measurement unit 127 measures the temperature Tref2 of the second reference resistor 124 using a temperature sensor 128 provided near the second reference resistor 124. The temperature sensor 128 is, for example, a temperature sensor using a thermistor, but may be a temperature sensor using other elements such as a thermocouple.

[0039] The second temperature control unit 129 controls the temperature of the second reference resistor 124 to be constant. Specifically, the second temperature control unit 129 acquires the temperature Tref2 of the second reference resistor 124 measured by the third temperature measurement unit 127, and controls the heater 130 so that the acquired temperature Tref2 becomes constant.

[0040] The communication interface unit 131 is a communication circuit for the battery monitoring device 100 to communicate with other battery monitoring devices or external devices. The communication interface unit 131 is used, for example, to transmit the SOH calculated by the second calculation unit to an external device. The communication performed by the communication interface unit 131 may be wireless communication or wired communication. The communication standard of the communication performed by the communication interface unit 131 is not particularly limited either.

[0041] [Operation] Next, the operation of the battery monitoring device 100 will be described. FIG. 4 is a flowchart of the operation of the battery monitoring device 100.

[0042] First, the signal application unit 109 applies a control signal to the control terminal of the transistor 104 (S11). As a result, the transistor 104 turns on and current flows through the first reference resistor 103.

[0043] In this operation, the signal application unit 109 generates a control signal having a plurality of frequency components. FIG. 5 is a diagram for explaining the method of generating the control signal.

[0044] The signal generation unit 110 of the signal application unit 109 generates, for example, a sine wave of frequency f1, a sine wave of frequency f2, and a sine wave of frequency f3, synthesizes them, and outputs the result. When the synthesized signal is subjected to Fourier transform, three frequency components of frequency f1, frequency f2, and frequency f3 appear.

[0045] The signal output from the signal generation unit 110 is a digital signal, and the output digital signal is converted into an analog signal by the waveform generation unit 111. That is, the waveform generation unit 111 is, for example, a DA (Digital to Analog) converter.

[0046] According to such a control signal, a current including a plurality of frequency components flows through the first reference resistor 103. Therefore, the first calculation unit 118 can calculate the AC impedance at each of the plurality of frequencies.

[0047] Next, the current measurement unit 112 measures the current Iac flowing through the first reference resistor 103 (S12). Specifically, the current measurement unit 112 measures the voltage across both ends of the first reference resistor 103. The voltage across both ends of the first reference resistor 103 is converted into a digital signal by the AD converter 113 and output to the first calculation unit 118 via the filter 114.

[0048] Next, the voltage measurement unit 115 measures the voltages V0 to V7 of the batteries B0 to B7 (S13). The voltages V0 to V7 are converted into digital signals by the AD converters 0 to 7 and output to the first calculation unit 118 via the filters 0 to 7.

[0049] Then, the first calculation unit 118 calculates the AC impedance of the batteries B0 to B7 based on the measured current Iac and the measured voltages V0 to V7 (S14). FIG. 6 is a diagram showing the specific configuration of the first calculation unit 118.

[0050] As shown in FIG. 6, specifically, the first calculation unit 118 includes a phase shift unit 118a, a conversion unit 118b, an integration unit 118c, an impedance calculation unit 118d, a temperature correction unit 118e, and a Kalman filter unit 118f. Also, in FIG. 6, the signal generation unit 110 and the second calculation unit 119 are also shown.

[0051] The signal generation unit 110 generates a sine wave (an example of the first signal). The phase shift unit 118a generates a cosine wave (an example of the second signal) by shifting the phase of the sine wave by 90 degrees. The phase shift unit 118a is realized by, for example, a delay circuit. In the battery monitoring device 100, the signal generation unit 110 included in the signal application unit 109 (that is, the signal generation unit 110 for generating a control signal) is also used as a signal generation unit for generating a sine wave for obtaining a complex current and a complex voltage. However, the sine wave for obtaining a complex voltage may be generated by a signal generation unit different from the signal generation unit 110.

[0052] The conversion unit 118b converts the current Iac into a complex current (an example of the second current) by multiplying each of the sine wave generated by the signal generation unit 110 and the cosine wave generated by the phase shift unit 118a by the current Iac. Also, the conversion unit 118b converts the voltages V0 to V7 into complex voltages (an example of the second voltage) by multiplying each of the sine wave generated by the signal generation unit 110 and the cosine wave generated by the phase shift unit 118a by the voltages V0 to V7. The conversion unit 118b is realized by, for example, a multiplication circuit.

[0053] The integration unit 118c performs averaging processing on the complex current and averaging processing on the complex voltage. The integration unit 118c is realized by, for example, an integration circuit.

[0054] The impedance calculation unit 118d calculates an AC impedance (described as a high-frequency impedance in FIG. 6) based on the complex current after the averaging process and the complex voltage after the averaging process. The impedance calculation unit 118d calculates the AC impedance by dividing the complex voltage after the averaging process by the complex current after the averaging process. For example, as the AC impedance of the battery B0, a real part of the impedance Z0re and an imaginary part of the impedance Z0im are output. The impedance calculation unit 118d is realized by, for example, a division circuit.

[0055] The temperature correction unit 118e corrects the AC impedance based on the temperature Tref1 of the first reference resistor 103 measured by the second temperature measurement unit 121. The temperature correction unit 118e corrects the AC impedance in the environment of the temperature Tref1 to an AC impedance equivalent to the reference temperature environment, for example.

[0056] As described above, since the first reference resistor 103 is arranged on a path P2 different from the path P1 of the current flowing from the battery B to the load 102, the AC impedance of the battery B can be calculated regardless of whether the battery B is being charged or discharged. Note that the AC impedance of the battery B is measured, for example, constantly, but may also be measured periodically (i.e., intermittently), or may be performed based on an instruction from an external device (for example, the integrated control unit described later).

[0057] [Calculation of SOH and SOC] The second calculation unit 119 calculates the SOH of the batteries B0 to B7 by estimating the circuit parameters of the equivalent circuits of the batteries B0 to B7 based on the AC impedance calculated by the first calculation unit 118. Various known calculation methods are used for the calculation of SOH based on the estimation of the circuit parameters.

[0058] In the calculation of SOH (that is, the estimation of the circuit parameters), in addition to the AC impedance (in other words, the high-frequency impedance), the low-frequency impedance may be used. The low-frequency impedance is the AC impedance for a frequency lower than the AC impedance calculated by the first calculation unit 118. Thereby, since the estimation of the circuit parameters is performed in consideration of the low-frequency impedance, the calculation accuracy of SOH can be improved.

[0059] The low-frequency impedance is calculated by the Kalman filter unit 118f. The Kalman filter unit 118f calculates the low-frequency AC impedance using at least one of the charging current when charging the batteries B0 to B7 and the discharging current when discharging the batteries B0 to B7.

[0060] Also, in the calculation of SOH (i.e., the estimation of circuit parameters), the temperatures Tcell0 to Tcell7 of the plurality of batteries B0 to B7 measured by the first temperature measurement unit 120 may be used. Thereby, since the estimation of circuit parameters is performed in consideration of the temperatures Tcell0 to Tcell7 of the plurality of batteries B0 to B7, the calculation accuracy of SOH can be improved.

[0061] Further, the second calculation unit 119 can also calculate the SOC of the batteries B0 to B7 by estimating the circuit parameters of the equivalent circuits of the batteries B0 to B7 based on the AC impedance calculated by the first calculation unit 118. Various known calculation methods are used for the calculation of SOC based on the estimation of circuit parameters.

[0062] [Modification Example of Control Signal Generation Method] The method of generating a control signal having a plurality of frequency components by the signal application unit 109 is not limited to the method as shown in FIG. 5. FIG. 7 is a first diagram for explaining the method of generating a control signal according to a modification example.

[0063] In the example of FIG. 7, the signal generation unit 110 outputs a rectangular wave as the control signal. In this case, the signal generation unit 110 has the same configuration as a pulse generator, and the frequency and voltage value of the control signal can be changed. When the rectangular wave is Fourier-transformed, a plurality of frequency components appear.

[0064] The signal output from the signal generation unit 110 is a digital signal, and the output digital signal is converted into an analog signal by the waveform generation unit 111. In the example of FIG. 7, the waveform generation unit 111 may be omitted.

[0065] Also, FIG. 8 is a second diagram for explaining the method of generating a control signal according to a modification example. In the example of FIG. 8, the signal generation unit 110 outputs a sine wave as the control signal.

[0066] The waveform generation unit 111 includes a burst waveform generation unit 111a, and the burst waveform generation unit 111a generates a control signal having a burst waveform based on the sine wave output from the signal generation unit 110. FIG. 9 is a diagram for explaining a method of generating a burst waveform.

[0067] The burst waveform is a waveform that includes a rectangular wave only in a part of the time domain. As shown in FIG. 9, the burst waveform generation unit 111a selectively outputs a rectangular wave only in the first period among the first period in which the sine wave becomes a positive value and the second period in which the rectangular wave becomes a negative value. That is, in the burst waveform, the first period in which the rectangular wave is output and the second period in which the rectangular wave is not output appear alternately. In this case, the control signal has a plurality of frequency components in the first period.

[0068] According to the control signal having such a burst waveform, since the rectangular wave is intermittently output, the power consumption is reduced.

[0069] [Modification example of the number of batteries] The battery pack 101 includes eight batteries B0 to B7, but the number of batteries included in the battery pack 101 may be nine or more or seven or less. Further, the battery monitoring device 100 may monitor a single battery B. FIG. 10 is a block diagram showing a functional configuration of a battery monitoring device 100c that monitors a single battery B0.

[0070] That is, a configuration in which an arbitrary number of integrated circuits 105 and the battery monitoring device 100 measure an arbitrary number of battery cells can be implemented in a scalable manner.

[0071] [Effects, etc.] As described above, the battery monitoring device 100 includes a first reference resistor 103 disposed on a path P2 different from the path P1 of the current flowing from the battery B to the load 102, a transistor 104 for flowing a current from the battery B to the first reference resistor 103, and an integrated circuit 105. The integrated circuit 105 includes a signal application unit 109 that applies a control signal to the control terminal of the transistor 104, a current measurement unit 112 that measures the first current flowing through the first reference resistor 103, a voltage measurement unit 115 that measures the voltage of the battery B, and a first calculation unit 118 that calculates the AC impedance of the battery B based on the measured first current and the measured first voltage.

[0072] In such a battery monitoring device 100, since the first reference resistor 103 is disposed on a path P2 different from the path P1 of the current flowing from the battery B to the load 102, the AC impedance of the battery B can be measured regardless of whether the battery B is being charged or discharged.

[0073] Also, the signal application unit 109 applies the control signal having a plurality of frequency components to the control terminal.

[0074] According to such a signal application unit 109, the first calculation unit 118 can calculate the AC impedance for a plurality of frequencies.

[0075] Also, for example, the signal application unit 109 can change the frequency and voltage value of the control signal.

[0076] According to such a signal application unit 109, the current flowing through the first reference resistor 103 can be arbitrarily adjusted.

[0077] Also, for example, the control signal has a burst waveform.

[0078] According to such a control signal having a burst waveform, since a rectangular wave is intermittently output, the power consumption is reduced.

[0079] Further, for example, the integrated circuit 105 includes a signal generation unit 110 that generates a first signal which is a sine wave, and a phase shift unit 118a that generates a second signal by shifting the phase of the first signal by 90 degrees. The first calculation unit 118 multiplies each of the generated first signal and second signal by the measured first current to convert the first current into a second current which is a complex current, multiplies each of the generated first signal and second signal by the measured first voltage to convert the first voltage into a second voltage which is a complex voltage, and calculates an AC impedance based on the second current and the second voltage.

[0080] Such a battery monitoring device 100 can calculate an AC impedance based on a complex voltage and a complex current.

[0081] Further, for example, the first calculation unit 118 performs an averaging process on the second current and an averaging process on the second voltage, and calculates an AC impedance based on the second current after the averaging process and the second voltage after the averaging process.

[0082] Such a battery monitoring device 100 can improve the calculation accuracy of the AC impedance by averaging.

[0083] Further, for example, the integrated circuit 105 further includes a second calculation unit 119 that calculates at least one of the SOC and SOH of the battery B using the calculated AC impedance.

[0084] Such a battery monitoring device 100 can calculate at least one of the SOC and SOH.

[0085] Further, for example, the first calculation unit 118 calculates AC impedances for a plurality of frequencies, and the second calculation unit 119 calculates the SOH using the AC impedances for the plurality of frequencies.

[0086] Such a battery monitoring device 100 can calculate the SOH using the AC impedances for a plurality of frequencies.

[0087] Also, for example, the integrated circuit 105 further includes a first temperature measurement unit 120 that measures the temperature of the battery B. The second calculation unit 119 calculates the SOH using the calculated AC impedance and the measured temperature of the battery B.

[0088] Such a battery monitoring device 100 can improve the calculation accuracy of the SOH by estimating the circuit parameters of the equivalent circuit of the battery B in consideration of the temperature of the battery B.

[0089] Also, for example, the first calculation unit 118 further includes a Kalman filter unit 118f that calculates the low-frequency AC impedance using at least one of the charging current when charging the battery B and the discharging current when discharging the battery B. The second calculation unit 119 calculates the SOH using the calculated AC impedance and the calculated low-frequency AC impedance.

[0090] Such a battery monitoring device 100 can improve the calculation accuracy of the SOH by estimating the circuit parameters of the equivalent circuit of the battery B in consideration of the low-frequency AC impedance of the battery B.

[0091] Also, for example, the integrated circuit 105 further includes a second temperature measurement unit 121 that measures the temperature of the first reference resistor 103. The first calculation unit 118 calculates the AC impedance using the measured temperature of the first reference resistor 103.

[0092] Such a battery monitoring device 100 can correct the AC impedance using the temperature of the first reference resistor 103.

[0093] Also, for example, the integrated circuit 105 includes a first temperature control unit 122 that controls the temperature of the first reference resistor 103 to be constant.

[0094] Such a battery monitoring device 100 can calculate the AC impedance in a state where the temperature of the first reference resistor 103 is constant.

[0095] Further, for example, the first calculation unit 118 calculates the AC impedance during charging of the battery B.

[0096] Such a battery monitoring device 100 can calculate the AC impedance during charging of the battery B.

[0097] Further, for example, the first calculation unit 118 calculates the AC impedance during discharging of the battery B.

[0098] Such a battery monitoring device 100 can calculate the AC impedance during discharging of the battery B.

[0099] Further, for example, the first calculation unit 118 calculates the AC impedance during the stop of charging and discharging of the battery B.

[0100] Such a battery monitoring device 100 can calculate the AC impedance during the stop of charging and discharging of the battery B.

[0101] Further, for example, the battery B is one of a plurality of batteries B0 to B7 included in the battery pack 101.

[0102] Such a battery monitoring device 100 can calculate the AC impedance of the battery B included in the battery pack 101.

[0103] Further, the integrated circuit 105 includes a transistor 104 for flowing a current from the battery B to a first reference resistor 103 disposed on a path P2 different from a path P1 through which a current flows from the battery B to the load 102, and the integrated circuit 105. The integrated circuit 105 includes a signal application unit 109 that applies a control signal to a control terminal of the transistor 104, a current measurement unit 112 that measures a first current flowing through the first reference resistor 103, a voltage measurement unit 115 that measures the voltage of the battery B, and a first calculation unit 118 that calculates the AC impedance of the battery B based on the measured first current and the measured first voltage.

[0104] Such an integrated circuit 105 can measure the AC impedance of the battery B regardless of whether the battery B is being charged or discharged because the first reference resistor 103 is disposed on a path P2 different from the path P1 through which the current flows from the battery B to the load 102.

[0105] Also, for example, the battery B is one of a plurality of batteries B0 to B7 included in the battery pack 101, and the voltage measurement unit 115 has a plurality of AD converters 0 to 7 for measuring the voltages of the respective batteries B0 to B7. The integrated circuit 105 further includes a reference bias generation unit 116 that supplies a reference voltage common to the plurality of AD converters 0 to 7.

[0106] Such an integrated circuit 105 can reduce the AD conversion error caused by variations in the reference voltage.

[0107] Also, for example, the battery B is one of a plurality of batteries B0 to B7 included in the battery pack 101, and the voltage measurement unit 115 has a plurality of AD converters 0 to 7 for measuring the respective voltages V0 to V7 of the plurality of batteries B0 to B7. The integrated circuit 105 further includes a timing signal generation unit 117 that supplies a timing signal for synchronizing the measurement timings of the plurality of AD converters 0 to 7 to each of the plurality of AD converters 0 to 7.

[0108] Such an integrated circuit 105 can measure the voltages V0 to V7 at the same timing.

[0109] Also, for example, the plurality of AD converters 0 to 7 have the same AD conversion characteristics.

[0110] Such an integrated circuit 105 can reduce the variations in the AD conversion of the AD converters 0 to 7.

[0111] (Embodiment 2) [Configuration and Operation] In Embodiment 2, a battery monitoring system including at least a plurality of battery monitoring devices 100 will be described. FIG. 11 is a block diagram showing the functional configuration of the battery monitoring system according to Embodiment 2.

[0112] As shown in FIG. 11, the battery monitoring system 200 includes a plurality of battery monitoring devices (specifically, battery monitoring device 100, battery monitoring device 100a, and battery monitoring device 100b), an integrated control unit 201, and a switch 202. The battery monitoring device 100 monitors the battery pack 101, the battery monitoring device 100a monitors the battery pack 101a, and the battery monitoring device 100b monitors the battery pack 101b. The battery pack 101, the battery pack 101a, and the battery pack 101b are connected in series.

[0113] The integrated circuit 105 included in the battery monitoring device 100 includes a communication interface unit 131. The battery monitoring device 100a has the same configuration as the battery monitoring device 100, and the integrated circuit 105a included in the battery monitoring device 100a includes a communication interface unit 131a. The battery monitoring device 100b has the same configuration as the battery monitoring device 100, and the integrated circuit 105b included in the battery monitoring device 100b includes a communication interface unit 131b.

[0114] The communication interface unit 131, the communication interface unit 131a, and the communication interface unit 131b are connected in a daisy chain. The communication interface unit 131 is connected to the communication interface unit 131a by a communication line 203, and the communication interface unit 131a is connected to the communication interface unit 131b by a communication line 204. The communication interface unit 131b is connected to the integrated control unit 201 by a communication line 205.

[0115] According to such communication lines 203, 204, and 205, the integrated control unit 201 can acquire the AC impedance of the battery pack 101 from the battery monitoring device 100, acquire the AC impedance of the battery pack 101a from the battery monitoring device 100a, and acquire the AC impedance of the battery pack 101a from the battery monitoring device 100b. Note that the integrated control unit 201 may acquire information (such as SOH, etc.) based on the AC impedance, which is different from the AC impedance, from the battery monitoring device 100, the battery monitoring device 100a, and the battery monitoring device 100b.

[0116] The integrated control unit 201 performs various controls based on the AC impedance acquired from the battery monitoring device 100, the battery monitoring device 100a, and the battery monitoring device 100b. For example, when the integrated control unit 201 determines based on the AC impedance that at least one of the battery packs 101, 101a, and 101b is deteriorated more than a predetermined standard, the integrated control unit 201 opens the switch 202 and disconnects the electrical connection between the load 102 and the battery packs 101, 101a, and 101b. Thereby, it is possible to suppress the occurrence of accidents such as ignition of the battery pack due to the use of the deteriorated battery pack. The integrated control unit 201 is realized, for example, by a microcomputer including a processor and a memory.

[0117] Note that in the battery monitoring system 200, the communication interface units 131, 131a, and 131b are daisy-chain connected, but such a connection method is an example. In the battery monitoring system 200, each of the communication interface units 131, 131a, and 131b may directly communicate with the integrated control unit 201. That is, the connection method between the communication interfaces is not particularly limited.

[0118] [Effects, etc.] As described above, the battery monitoring system 200 includes a plurality of battery monitoring devices and an integrated control unit 201 that acquires the AC impedance from each of the plurality of battery monitoring devices.

[0119] Accordingly, the integrated control unit 201 can perform various controls based on the AC impedances acquired from the plurality of battery monitoring devices.

[0120] (Embodiment 3) [Configuration and Operation] In Embodiment 3, a battery monitoring system including a cloud server will be described. FIG. 12 is a diagram showing an overview of the battery monitoring system according to Embodiment 3.

[0121] As shown in FIG. 12, the battery monitoring system 300 includes a battery monitoring device 100 and a server device 301. The server device 301 is a server device arranged at a location separated from the battery monitoring device 100. The server device 301 is a so-called cloud server. The server device 301 is communicatively connected to, for example, other server devices via a cloud network 302.

[0122] The battery monitoring device 100 is mounted on, for example, an automobile 400 such as an EV, and monitors a battery pack 101 for driving a motor 401 of the automobile 400. A communication interface unit 131 included in the battery monitoring device 100 transmits, for example, the calculated AC impedance of the battery pack 101 to the server device 301 by wireless communication. Note that a relay device (not shown) may be interposed between the communication interface unit 131 and the server device 301.

[0123] The server device 301 acquires the AC impedance from the battery monitoring device 100 and stores it in a storage unit (not shown) included in the server device 301. The server device 301 performs various controls based on the AC impedance acquired from the battery monitoring device 100.

[0124] When the server device 301 determines, for example, based on the AC impedance, that the assembled battery 101 has deteriorated more than a predetermined standard, the server device 301 transmits information for stopping the use of the assembled battery 101 to the battery monitoring device 100. Thereby, it is possible to suppress the occurrence of accidents such as ignition of the assembled battery 101 caused by the use of the deteriorated assembled battery 101.

[0125] [Effects, etc.] As described above, the battery monitoring system 300 includes a battery monitoring device 100 and a server device 301 disposed at a location separate from the battery monitoring device 100. The server device 301 acquires the AC impedance from the battery monitoring device 100.

[0126] Thereby, the server device 301 can perform various controls based on the AC impedance acquired from the battery monitoring device 100.

[0127] [Other Embodiments] Although the embodiments have been described above, the present disclosure is not limited to the above embodiments.

[0128] For example, in the above embodiment, the battery monitoring device for monitoring the battery used in an automobile such as an EV has been described, but the battery monitoring device may monitor batteries for any application.

[0129] Also, the circuit configuration described in the above embodiment is an example, and the present disclosure is not limited to the above circuit configuration. That is, similar to the above circuit configuration, a circuit that can realize the characteristic functions of the present disclosure is also included in the present disclosure. For example, within the range where the same functions as the above circuit configuration can be realized, a circuit in which an element such as a switching element (transistor), a resistance element, or a capacitance element is connected in series or in parallel to a certain element is also included in the present disclosure.

[0130] In addition, in the above embodiment, the components included in the integrated circuit are realized by hardware. However, some of the components included in the integrated circuit may be realized by executing a software program suitable for the component. Some of the components included in the integrated circuit may be realized by a program execution unit such as a CPU (Central Processing Unit) or a processor reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory.

[0131] In addition, in the above embodiment, the processing executed by a specific processing unit may be executed by another processing unit. Also, in the operations described in the above embodiment, the order of a plurality of processes may be changed, or a plurality of processes may be performed in parallel.

[0132] In addition, forms obtained by applying various modifications conceivable by those skilled in the art to each embodiment, or forms realized by arbitrarily combining the components and functions in each embodiment without departing from the spirit of the present disclosure are also included in the present disclosure.

Description of Reference Numerals

[0133] 100, 100a, 100b, 100c Battery monitoring device 101, 101a, 101b Battery pack 102 Load 103 First reference resistor 104 Transistor 105, 105a, 105b Integrated circuit (battery monitoring circuit) 106 Load resistor 107, 128 Temperature sensor 108, 130 Heater 109 Signal application unit 110 Signal generation unit 111 Waveform generation unit 111a Burst waveform generation unit 112 Current measurement unit 113, 125 AD converter 114, 126 Filter 115 Voltage measurement unit 116 Reference bias generation unit 117 Timing signal generation unit 118 First calculation unit 118a Phase shift unit 118b Conversion unit 118c Integration unit 118d Impedance calculation unit 118e Temperature correction unit 118f Kalman filter unit 119 Second calculation unit 120 First temperature measurement unit 121 Second temperature measurement unit 122 First temperature control unit 123 Load current measurement unit 124 Second reference resistor 127 Third temperature measurement unit 129 Second temperature control unit 131, 131a, 131b Communication interface unit 200, 300 Battery monitoring system 201 Integrated control unit 202 Switch 203, 204, 205 Communication line 301 Server device 302 Cloud network 400 Automobile 401 Motor B, B0~B7 Battery Iac, Iad Current V0~V7 Voltage

Claims

1. A battery monitoring device comprising: a resistor disposed on a path different from a path of a current flowing from a battery to a load; a transistor for flowing a current from the battery to the resistor; and an integrated circuit. The integrated circuit includes: a signal application unit that applies a control signal to a control terminal of the transistor; a current measurement unit that measures a first current flowing through the resistor; a voltage measurement unit that measures a first voltage of the battery; a first calculation unit that calculates a high-frequency AC impedance of the battery based on the measured first current and the measured first voltage, and calculates a low-frequency AC impedance using at least one of a charging current when charging the battery and a discharging current when discharging the battery; a reference bias generation unit; and a timing signal generation unit. The voltage measurement unit includes a plurality of first AD (Analog to Digital) converters for measuring the first voltage of each of a plurality of batteries including the battery. The current measurement unit includes a second AD converter for measuring the first current. The reference bias generation unit supplies a common reference voltage to the plurality of first AD converters and the second AD converter. The timing signal generation unit generates a timing signal for synchronizing the measurement timings of the plurality of first AD converters and the second AD converter. A battery monitoring device.

2. The signal application unit applies the control signal having a plurality of frequency components to the control terminal. The battery monitoring device according to claim 1.

3. The signal application unit can change a frequency and a voltage value of the control signal. The battery monitoring device according to claim 2.

4. The control signal has a burst waveform. The battery monitoring device according to claim 2 or 3.

5. The integrated circuit further includes: a signal generation unit that generates a first signal that is a sine wave; and a phase shift unit that generates a second signal by shifting a phase of the first signal by 90 degrees. The battery monitoring device according to any one of claims 1 to 4.

6. The first calculation unit: converts the first current into a second current that is a complex current by multiplying each of the generated first signal and the second signal by the measured first current; and calculates the high-frequency AC impedance based on the second current. The battery monitoring device according to claim 5.

7. The first calculation unit: Converting the first voltage into a second voltage which is a complex voltage by multiplying each of the generated first signal and the second signal by the measured first voltage, Calculating the high-frequency AC impedance based on the second voltage The battery monitoring device according to claim 5 or 6.

8. The integrated circuit further includes a second calculation unit that calculates the state of health (SOH) of the battery using the calculated high-frequency AC impedance and the calculated low-frequency AC impedance. The battery monitoring device according to any one of claims 1 to 6.

9. The second calculation unit further calculates the state of charge (SOC) of the battery using the calculated high-frequency AC impedance. The battery monitoring device according to claim 8.

10. The integrated circuit further includes a second temperature measurement unit that measures the temperature of the resistor, The first calculation unit further calculates the high-frequency AC impedance using the measured temperature of the resistor. The battery monitoring device according to any one of claims 1 to 9.

11. The integrated circuit further includes a temperature control unit that controls the temperature of the resistor to be constant. The battery monitoring device according to any one of claims 1 to 10.

12. The first calculation unit, Converting the first current into a second current which is a complex current by multiplying each of the generated first signal and the second signal by the measured first current, Converting the first voltage into a second voltage which is a complex voltage by multiplying each of the generated first signal and the second signal by the measured first voltage, Comprising an integration circuit that averages the second current and the second voltage, Calculating the high-frequency AC impedance of the battery after the averaging process by the integration circuit. The battery monitoring device according to claim 5.

13. The first calculation unit calculates the high-frequency AC impedance during charging of the battery. The battery monitoring device according to any one of claims 1 to 12.

14. The first calculation unit calculates the high-frequency AC impedance during discharging of the battery. The battery monitoring device according to any one of claims 1 to 12.

15. The first calculation unit calculates the high-frequency AC impedance during the stop of charging and discharging of the battery. The battery monitoring device according to any one of claims 1 to 12.

16. The battery is one of the plurality of batteries included in the battery pack. The battery monitoring device according to any one of claims 1 to 15.

17. A signal application unit that applies a control signal to a control terminal of a transistor for flowing a current from the battery to a resistor disposed on a path different from a path of a current flowing from the battery to a load, A current measurement unit that measures a first current flowing through the resistor, A voltage measurement unit that measures a first voltage of the battery, A first calculation unit that calculates a high-frequency AC impedance of the battery based on the measured first current and the measured first voltage, and calculates a low-frequency AC impedance using at least one of a charging current when charging the battery and a discharging current when discharging the battery, A reference bias generation unit, And a timing signal generation unit, The voltage measurement unit includes a plurality of first AD converters for measuring the first voltage of each of the plurality of batteries including the battery, The current measurement unit includes a second AD converter for measuring the first current, The reference bias generation unit supplies a common reference voltage to the plurality of first AD converters and the second AD converter, The timing signal generation unit generates a timing signal for synchronizing the measurement timings of the plurality of first AD converters and the second AD converter Integrated circuit.

18. The battery is one of the plurality of batteries included in the battery pack, The integrated circuit supplies the generated timing signal to each of the plurality of first AD converters and the second AD converter The integrated circuit according to claim 17.

19. A plurality of the battery monitoring devices according to any one of claims 1 to 16 are provided, An integrated control unit that acquires the high-frequency AC impedance from each of the plurality of battery monitoring devices is provided Battery monitoring system.

20. The battery monitoring device according to any one of claims 1 to 16, And a server device disposed at a location separated from the battery monitoring device, The server device acquires the high-frequency AC impedance from the battery monitoring device Battery monitoring system.

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