Peak hold device, impedance measurement device, metal precipitation detector, and battery inside temperature estimation device

Abstract

To provide a peak hold device which can acquire an arbitrary peak value of an attenuation vibration waveform.SOLUTION: A peak hold device 100 starts holding the value of an attenuation vibration waveform at a time before a target peak which is one of the largest peak and the smallest peak of a target of which peak value is to be acquired and repeats processing of stopping holding the value of the attenuation vibration waveform at a time after the target peak for a plurality of attenuation vibration waveforms.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a peak hold device, an impedance measuring device, a metal deposition detection device, and a battery internal temperature estimating device. [Background technology]

[0002] Patent Document 1 discloses a peak hold circuit that includes a switch that turns on when the output voltage is increased and turns off when the output voltage is maintained, a capacitance that accumulates charge when the output voltage is increased and retains the charge when the output voltage is maintained, a reset switch that discharges the charge accumulated in the capacitance with a reset signal to initialize the circuit, a voltage comparator that outputs a voltage that turns the switch on when the input signal is equal to or greater than a reference voltage and outputs a voltage that turns the switch off when the input voltage is less than the reference voltage, and a voltage attenuation circuit that attenuates the output voltage and outputs it as a reference voltage for the voltage comparator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-112786 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the peak waveform targeted by the conventional peak hold circuit is a single instantaneous pulse peak or the peak value of the same pulse waveform input continuously. Due to the speed performance rate limiting factor of the circuit, the peak value of a single pulse can be accurately acquired at low frequencies, but it is difficult to accurately acquire the peak value of a single pulse at high frequencies. In contrast, for continuous pulses, the voltage value according to the charge held in the capacitance gradually tracks the peak value, and the peak value can be accurately acquired even at high frequencies. On the other hand, in order to acquire an accurate peak value, it is necessary to accumulate the charge many times to track the peak value, which results in a problem of a long measurement time. By making the capacitance for holding the charge smaller, it is possible to track the peak value with fewer times, but there is a problem of a large voltage drop due to leakage current, which reduces the accuracy of the peak value. [Means for solving the problem]

[0005] One aspect of the present invention is a peak hold device that acquires the peak value of any maximum or minimum peak contained in a damped vibration waveform, and is characterized in that the maximum or minimum peak from which the peak value is to be acquired is set as a target peak, and a process of starting to hold the value of the damped vibration waveform at a time before the target peak and stopping to hold the value of the damped vibration waveform at a time after the target peak is repeated for a plurality of the damped vibration waveforms.

[0006] Here, it is preferable to start holding the value of the damped oscillation waveform at a time before the target peak, and then hold the value of the damped oscillation waveform including a maximum peak or minimum peak other than the target peak.

[0007] It is also preferable to provide a peak hold circuit including a charging circuit including a capacitor, a switch for starting or stopping charging of the capacitor, and a comparator, wherein the comparator compares an output voltage value of the peak hold circuit with a voltage value of the damped oscillation waveform to output a comparison result, turns on the switch in accordance with the comparison result at a time before the target peak to start charging the capacitor, and turns off the switch in accordance with the comparison result at a time after the target peak to stop charging the capacitor.

[0008] It is also preferable that the charging circuit includes a resistor between the capacitor and a charging section that supplies power to the capacitor.

[0009] It is also preferable that the resistor is a variable resistor, and charging of the capacitor is controlled by changing a resistance value of the variable resistor in conjunction with a change in the output voltage of the peak hold circuit.

[0010] Another aspect of the present invention is an impedance measuring device that measures a real impedance part and an imaginary impedance part of a battery using the peak value acquired by the peak hold device.

[0011] Another aspect of the present invention is a metal deposition detection device that estimates an amount of metal deposition in a lithium ion battery from an amount of decrease in the real impedance measured by the impedance measuring device.

[0012] Another aspect of the present invention is a battery internal temperature estimation device, characterized in that the internal temperature of the battery is estimated from the amount of change in at least one of the real impedance and the imaginary impedance measured by the impedance measuring device. Effect of the Invention

[0013] According to the present invention, it is possible to provide a peak hold device capable of more quickly acquiring any peak value of a damped oscillation waveform, an impedance measuring device, a metal deposition detection device, and a battery internal temperature estimation device using the same. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram showing a configuration of a peak hold device according to an embodiment of the present invention. [Diagram 2] 5 is a flowchart showing a peak hold process according to the embodiment of the present invention. [Diagram 3] FIG. 4 is a diagram showing a sequence of a peak hold process in the embodiment of the present invention. [Figure 4] 5A and 5B are diagrams illustrating an example of a time change in a damped oscillation waveform of a resonant voltage in the embodiment of the present invention. [Diagram 5] FIG. 2 is a diagram illustrating an example of a peak hold circuit according to an embodiment of the present invention. [Figure 6] FIG. 2 is a diagram illustrating an example of a peak hold circuit according to an embodiment of the present invention. [Figure 7] FIG. 2 is a diagram illustrating an example of a peak hold circuit according to an embodiment of the present invention. [Figure 8] FIG. 2 is a diagram illustrating an example of a peak hold circuit according to an embodiment of the present invention. [Figure 9] FIG. 4 is a diagram showing the relationship between the impedance and the amount of lithium deposition of a battery according to an embodiment of the present invention. [Figure 10] FIG. 4 is a diagram showing the relationship between impedance and internal temperature of a battery according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 1, a peak hold device 100 according to an embodiment of the present invention includes a resonant circuit 102, a differential single conversion circuit 104, and a peak hold circuit 106. The peak hold device 100 is connected to a battery BAT, and acquires, holds, and outputs the peak voltage value of any maximum or minimum peak contained in a signal having a damped oscillation waveform generated by the resonant circuit 102.

[0016] The resonant circuit 102 is connected to a battery BAT and a switch SW res The resonant circuit 102 converts the voltage of the battery BAT into a resonant voltage having a damped oscillatory waveform and outputs the converted voltage. res , L sec , resonant capacitance C res , and the resonant resistance R res The resonant inductor L res and the resonant inductor L sec has a transformer structure having a mutual inductor M.

[0017] The differential to single conversion circuit 104 includes a resonant inductor L sec The resonant voltage V res The differentially amplified signal is output to the peak hold circuit 106 .

[0018] The peak hold circuit 106 is a non-inverting peak hold circuit including a comparator CP. The inverting input terminal of the comparator CP receives the output voltage value (peak hold voltage value) V pho is input to the non-inverting input terminal of the comparator CP, and the resonant voltage V output from the differential to single conversion circuit 104 is input to the non-inverting input terminal of the comparator CP. res is input. The comparator CP detects the resonant voltage V res is the output voltage value V pho When the pulse signal is higher than V co Generates a switch SW sp When the switch SW ch On the other hand, the resonant voltage V res is the output voltage value V phoWhen the voltage is lower than 1V, the switch SW sp Even if the switch SW ch Turn off the switch SW sp When the comparator CP is in the off state, the pulse signal V co Regardless of whether or not the switch SW ch The switch SW ch When turned on, the charge capacity C c From the charging part (voltage source) that supplies power to the resistor R c Charge capacity C via c Current flows through the charge capacitance C c Charge is stored in the charge capacitance C c The terminal voltage of the charge capacitance C c The terminal voltage of the peak hold circuit 106 is the output voltage value V pho The charge capacity C c To discharge and reset the charge stored in the dch Turn on .

[0019] Here, the resistance R c and charge capacity C c The charge capacity C c The terminal voltage is the resonant voltage V res However, the resonant voltage V res When the frequency is high, the resonant voltage V res and the output voltage value V of the peak hold circuit 106 pho Therefore, the error with resistor R c and charge capacity C c The time constant of one operation is the charge capacity C c The terminal voltage is the resonant voltage V res It is preferable to set the resistor R c By providing a charge capacity C cThe lower the terminal voltage, the faster the charge is charged, and the higher the terminal voltage, the slower the charge is charged, resulting in a resonant voltage V res It is possible to acquire and hold the peak voltage values ​​of the peaks with high accuracy.

[0020] FIG. 2 shows the resonant voltage V res 3 is a flowchart showing a peak hold process for acquiring and holding a peak voltage value of a resonant voltage V having a damped oscillation waveform. res 4 shows a sequence for peak-holding the peak voltage value of the second peak of the first voltage Vcc set as a target peak.

[0021] In step S10, the switch SW dch Turn off the charge capacity C c The charge is then transferred from the reset state in which the charge is discharged to a state in which the charge can be stored. At this time, the count value of the number of times the process is repeated is also reset to 0.

[0022] In step S12, the switch SW res This causes the resonant voltage V having a damped oscillation waveform to be generated from the resonant circuit 102. res At this time, the count value count of the number of times the process is repeated is incremented by 1. res The following shows an example of the time change of the damped oscillation waveform of the resonant voltage V res The peak value V at time t1 is reached as time progresses on the horizontal axis. res (t1), and at time t2, the peak value V res (t2), and the elapsed time t n Odor peak value V res (t n ) is shown.

[0023] In step S14, a delay process is performed for a predetermined delay time. The delay time is determined by the switch SW res The resonant voltage V has a damped oscillatory waveform from the time it is turned on.res In particular, set the switch SW at a position between 1 / 4 wavelength and 3 / 4 wavelength of the target peak. sp It is preferable to set the delay time so that the resonant voltage V having a damped oscillation waveform is turned on from off. res When the second peak is set as the peak to be held, switch SW res When the resonant voltage V is turned on, the damped oscillatory waveform is generated. res The delay time is set to be after time t1 of the first peak, which is one before the target peak, based on the time when the peak started to be generated, and before time t2 of the second peak, which is the target peak.

[0024] In step S16, the switch SW sp This changes the output voltage V pho is the resonant voltage V res A pulse signal V is generated when co Switch SW ch is turned on.

[0025] The comparator CP detects the output voltage V pho and the resonant voltage V input to the non-inverting input terminal res Compare with the resonant voltage V res is the output voltage value V pho When the pulse signal is higher than V co Generates a switch SW ch In this state, resistor R c Charge capacity C via c Current flows through the charge capacitance C c Charge is stored in the charge capacitance C c The terminal voltage and the output voltage V pho increases.

[0026] As shown in the enlarged view of Figure 3, the comparator CP outputs an output voltage value V pho is the resonant voltage Vres When it exceeds the threshold, a pulse signal V co Since the switch SW sp When the output voltage is V pho is the resonant voltage V res Until the resonant voltage V res Charge capacitance C c The charge to is repeatedly charged. Meanwhile, the comparator CP detects the resonant voltage V res is the output voltage value V pho If it is higher than this, no pulse signal will be generated and the charge capacitance C c The charging of the charge to the

[0027] In step S18, a delay process is performed for a predetermined delay time. The delay time is determined by the switch SW res The resonant voltage V has a damped oscillatory waveform from the time it is turned on. res After the peak to be held, the next resonant voltage V res For example, in FIG. 4, the resonant voltage V res When the second peak is set as the peak to be held, switch SW res When the resonant voltage V is turned on, the damped oscillatory waveform is generated. res The time when the resonant voltage V res The delay time is set to a time before the occurrence of the event.

[0028] In step S20, the switch SW sp This causes the pulse signal V at the output of the comparator CP to change from ON to OFF. co is the switch SW ch The output voltage V pho and the resonant voltage V res Regardless of the high or low relationship with the switch SW ch is turned off.

[0029] In step S22, the switch SWres This causes the resonant voltage V having a damped oscillation waveform to be generated from the resonant circuit 102. res The output of is stopped.

[0030] In step S24, a delay process is performed for a predetermined delay time. The delay time is set to the resonant voltage V res is the waiting time until the resonant voltage V res The previous resonant voltage V res It is preferable to set the time over which the decay occurs.

[0031] In step S26, the count value "count" is set to the maximum count "Cnt max It is determined whether the count value "count" has reached the maximum count "Cnt" or not. max If it has reached the maximum count Cnt, the process proceeds to step S28, and if it has not reached the maximum count Cnt, the process returns to step S12 and the peak hold process for the same peak is repeated. max may be preset so that the process is repeated to an extent that the peak hold process is performed reliably.

[0032] By repeating the processes from step S12 to step S26, the output voltage value V pho The peak hold process is performed as shown in the change in the first resonant voltage V res The second, third, and fourth peaks of the damped oscillations cause the charge capacitance C c As a result, the output voltage V gradually decreases until it reaches a voltage higher than the fifth peak. pho The second resonant voltage V res Then, the second and third peaks of the damped oscillation further increase the charge capacitance C c The charge is charged to the output voltage V pho The third resonant voltage V resThen, the second and third peaks of the damped oscillation further increase the charge capacitance C c The charge is charged to the output voltage V pho The 4th to 6th resonant voltages V res Then, the second peak of the damped oscillation further increases the charge capacitance C c As a result, the output voltage V pho rises, and the peak voltage value of the second peak, which is the target peak, becomes the output voltage value V pho are acquired and held as

[0033] In this way, in the peak hold device 100 of the present embodiment, not only the target peak that is the target of the peak hold process, but also the resonant voltage V res The charge capacity C c Therefore, the output voltage V pho can be more quickly raised to the peak voltage value of the target peak.

[0034] In step S28, the output voltage value V pho The output voltage value V obtained and held in steps S10 to S26 is read out. pho is read out.

[0035] In step S30, it is determined whether or not to perform peak hold for the next peak. If the peak hold process is to be performed for the next peak, the process proceeds to step S34, and if the peak hold process is to be ended, the process proceeds to step S32.

[0036] In step S32, the switch SW dch Turn on the charge capacity C cis discharged to reset the state, and the peak hold process is terminated. In step S34, the next peak is set as the target peak, and the peak hold process for the target peak is started. Here, the switch SW dch Turn on the charge capacity C c Discharge the switch SW dch In step S36, the count value "count" is reset to 0, and the process is repeated from step S12.

[0037] The resonant voltage V res In this case, the target peak is changed from a lower peak voltage value in the latter case to a higher peak voltage value in the former case, so that the peak voltage value of each peak is changed to the output voltage value V pho After acquiring and holding the signal as dch Turn on the charge capacity C c That is, it is not necessary to discharge the output voltage V pho The charge capacitance C is then calculated by taking the previous peak with a higher peak voltage value as the next target peak. c Without discharging the charge that had been accumulated up until then, further charge is charged to match the peak voltage value of the next target peak, and the output voltage value V pho may be acquired and held as such.

[0038] As described above, the peak hold device 100 of the present embodiment detects the resonant voltage V res In the peak hold device 100, the charge capacity C c By using an integrating type in which the charge is charged to the resonant voltage V multiple times, the amount of tracking per time becomes small, but the accuracy of tracking the peak voltage value becomes high. Therefore, the resonant voltage V having a high-frequency damped oscillation waveform exceeding 10 kHz, which is difficult to track the peak by a single peak hold process, is res Even if the peak voltage is the output voltage Vpho It is possible to acquire and hold the signal with higher accuracy.

[0039] 5 to 8 show examples of the peak hold circuit 106. FIG. 5 shows a non-inverting type peak hold circuit including a comparator CP applied to the peak hold device 100 shown in FIG. 1. The non-inverting type peak hold circuit detects a resonant voltage V res This is used to obtain the peak voltage value of the positive peak (maximum peak) of the resonant voltage V. Figure 6 shows an inverting peak hold circuit including a comparator CP. The inverting peak hold circuit res This is used to obtain the peak voltage value of the negative peak (minimum peak) of the charge capacitance C c In the charge supply circuit to c This is a non-inverting peak hold circuit in which the voltage source via the charge capacitance C is changed to a constant current source CS. c In the charge supply circuit to c This is a non-inverting peak hold circuit in which the resistor R c By making it a variable resistor, the charge capacitance C c Since the time constant for charging the capacitor C can be varied, it is possible to obtain the peak voltage value more quickly and accurately. The configurations in Figures 7 and 8 can also be applied to an inverting peak hold circuit that includes a comparator CP.

[0040] [How to calculate battery impedance] A method for calculating the internal impedance of the battery BAT will be described below.

[0041] Resonant voltage V res (t) is expressed by the formulas (1) to (6). Here, the voltage V of the battery BAT bat , internal capacity C bat , internal inductance L bat and internal resistance R bat , the resonant capacitance C of the resonant circuit 102 res , the resonant inductance L of the resonant circuit 102 res (Primary side), L sec (secondary side), resonant inductance Lres (primary side) and resonant inductance L sec (Secondary side) mutual inductance M, resonance resistance R res , resonant angular frequency ω0, resonant inductance L res (primary side) and internal inductance L bat The series combined inductance L s , resonant capacitance C res and the internal capacitance C bat The series combined capacitance C s , the elapsed time from the start of resonance t n , the damping rate α of the damped resonant voltage, and the phase difference β of the damped resonant voltage.

number

number

number

number

number

number

[0042] The resonant voltage V res (t n ) is expressed by equation (7).

number

[0043] For any n = n1, n2 (n1>n2), the attenuation rate α is expressed by equation (8).

number

[0044] The resonant resistance R of the resonant circuit 102 resis the internal resistance R of the battery BAT bat Sufficiently larger than (R res >>R bat ), the resonance angular frequency ω0 is expressed by equation (9).

number

[0045] The real impedance R of the battery BAT bat , imaginary impedance L bat can be calculated using formulas (10) and (11). However, the internal capacity C of the battery BAT bat is so large that it can be ignored.

number

number

[0046] As described above, the resonant voltage V obtained by the peak hold device 100 res Based on the peak voltage value of the maximum or minimum peak of (t), the real impedance R of the battery BAT is calculated. bat and the imaginary impedance L bat can be calculated.

[0047] [Method for detecting the amount of lithium deposition inside a battery] Figure 9 shows the change in the real impedance (1 MHz) of the battery BAT versus the amount of lithium (Li) deposited when the battery BAT is a lithium-ion battery. The figure shows the results of a degradation test in which lithium (Li) was deposited by repeatedly charging a commercially available cylindrical lithium-ion battery at a low temperature and at a high rate.

[0048] As shown in FIG. 9, the amount of lithium (Li) deposited in the battery BAT shows a linear relationship with the change in the real impedance of the battery BAT, and the amount of lithium (Li) deposited in the battery BAT can be estimated by the formula: Amount of Lithium Deposition = Amount of Change in the Real Impedance of the Battery BAT × Coefficient.

[0049] [Method of estimating the internal temperature of a battery] 10 shows the change in the real impedance and imaginary impedance (1 MHz) of the battery BAT with respect to the internal temperature of the battery BAT. The change in the real impedance and imaginary impedance of the battery BAT shows a linear relationship with the internal temperature of the battery BAT, and the internal temperature of the battery BAT can be estimated by the formula: internal temperature of the battery BAT = coefficient x change in impedance + reference temperature.

[0050] [Configuration of the present invention] [Configuration 1] A peak hold device for acquiring a peak value of any maximum or minimum peak included in a damped oscillation waveform, A peak hold device characterized in that a maximum or minimum peak for which the peak value is to be obtained is set as a target peak, and a process of starting to hold the value of the damped oscillation waveform at a time before the target peak and stopping to hold the value of the damped oscillation waveform at a time after the target peak is repeated for a plurality of the damped oscillation waveforms. [Configuration 2] The peak hold device according to configuration 1, A peak hold device characterized in that after starting to hold the value of the damped oscillation waveform at a time before the target peak, the device holds values ​​of the damped oscillation waveform including maximum peaks or minimum peaks other than the target peak. [Configuration 3] The peak hold device according to configuration 1 or 2, a charging circuit including a capacitor; a switch for starting or stopping charging the capacitor; A comparator; A peak hold circuit including: the comparator compares the output voltage value of the peak hold circuit with the voltage value of the damped oscillation waveform and outputs a comparison result; A peak hold device characterized in that at a time before the target peak, the switch is turned on in accordance with the comparison result to start charging the capacitor, and at a time after the target peak, the switch is turned off in accordance with the comparison result to stop charging the capacitor. [Configuration 4] The peak hold device according to configuration 3, The peak hold device according to the present invention, wherein the charging circuit includes a resistor between the capacitor and a charging section that supplies power to the capacitor. [Configuration 5] The peak hold device according to configuration 4, the resistor is a variable resistor, A peak hold device, characterized in that the charging of the capacitor is controlled by changing the resistance value of the variable resistor in conjunction with a change in the output voltage of the peak hold circuit. [Configuration 6] 6. An impedance measuring device, comprising: a peak value obtained by the peak hold device according to any one of configurations 1 to 5; and a real impedance part and an imaginary impedance part of a battery. [Configuration 7] 7. A metal deposition detection device for estimating an amount of metal deposition in a lithium ion battery from an amount of decrease in the real impedance measured by the impedance measuring device according to claim 6. [Configuration 8] 7. A battery internal temperature estimation device, comprising: an impedance measuring device according to claim 6, configured to estimate an internal temperature of a battery from a change in at least one of the real impedance part and the imaginary impedance part measured by the impedance measuring device according to claim 6. [Explanation of symbols]

[0051] 100 peak hold device, 102 resonant circuit, 104 differential single conversion circuit, 106 peak hold circuit, BAT battery, CP comparator, CS constant current source, SW ch Switch, SW dch Switch, SW res Switch, SW sp switch.

Claims

1. A peak hold device for acquiring a peak value of any maximum or minimum peak included in a damped oscillation waveform, A peak hold device characterized in that a maximum or minimum peak for which the peak value is to be obtained is set as a target peak, and a process of starting to hold the value of the damped oscillation waveform at a time before the target peak and stopping to hold the value of the damped oscillation waveform at a time after the target peak is repeated for a plurality of the damped oscillation waveforms.

2. 2. The peak hold device according to claim 1, A peak hold device characterized in that after starting to hold the value of the damped oscillation waveform at a time before the target peak, the device holds values ​​of the damped oscillation waveform including maximum peaks or minimum peaks other than the target peak.

3. 3. The peak hold device according to claim 1 or 2, a charging circuit including a capacitor; a switch for starting or stopping charging the capacitor; A comparator; A peak hold circuit including: the comparator compares the output voltage value of the peak hold circuit with the voltage value of the damped oscillation waveform and outputs a comparison result; A peak hold device characterized in that at a time before the target peak, the switch is turned on in accordance with the comparison result to start charging the capacitor, and at a time after the target peak, the switch is turned off in accordance with the comparison result to stop charging the capacitor.

4. 4. The peak hold device according to claim 3, The peak hold device according to the present invention, wherein the charging circuit includes a resistor between the capacitor and a charging section that supplies power to the capacitor.

5. 5. The peak hold device according to claim 4, the resistor is a variable resistor, A peak hold device, comprising: a variable resistor that changes a resistance value of the variable resistor in response to a change in an output voltage of the peak hold circuit, thereby controlling charging of the capacitor.

6. 2. An impedance measuring device, comprising: a peak hold device according to claim 1; and a real impedance part and an imaginary impedance part of a battery, the real impedance part and the imaginary impedance part being measured by using the peak value acquired by the peak hold device according to claim 1.

7. 7. A metal deposition detection device, comprising: a metal deposition detection unit for estimating an amount of metal deposition in a lithium ion battery from an amount of decrease in the real impedance measured by the impedance measuring device according to claim 6.

8. 7. An apparatus for estimating an internal temperature of a battery, comprising: an impedance measuring apparatus according to claim 6, wherein the internal temperature of the battery is estimated from a change in at least one of the real impedance part and the imaginary impedance part measured by the impedance measuring apparatus according to claim 6.

Images