Patent ID: 12199251

DESCRIPTION OF EMBODIMENT

FIG.1is a perspective view schematically illustrating a schematic configuration of battery pack1according to an exemplary embodiment. Battery pack1includes battery module (assembled battery)2and control substrate3. Battery module2includes a plurality of cells C1. For each of cells C1, a lithium-ion battery cell, a nickel hydrogen battery cell, a lead battery cell, or the like can be used. Hereinafter, an example using lithium-ion battery cells (nominal voltage: from 3.6 V to 3.7 V) is assumed in the present specification.

In an example illustrated inFIG.1, the plurality of cylindrical cells C1are connected in parallel to form battery module2. In reality, parallel cells in which the plurality of cylindrical cells C1are connected in parallel are connected in series to form battery module2. The number of series connections of the parallel cells is determined by a voltage required by an application. Furthermore, the number of parallel connections in each parallel cell is determined according to a capacity required for an application.

Control substrate3is horizontally arranged on an upper part of battery module2in battery pack1. The arrangement position and orientation of control substrate3are not limited to the example illustrated inFIG.1, and the designer can arbitrarily design control substrate3. A control device for managing a state of battery module2is mounted on control substrate3. Further, in the present exemplary embodiment, impact detection device10for detecting an impact applied to battery pack1is mounted on control substrate3.

Connecting portion4is installed on a bottom surface of battery pack1. Connecting portion4includes a positive-electrode terminal connected to a positive electrode of battery module2, a negative-electrode terminal connected to a negative electrode of battery module2, and a control terminal connected to control substrate3. Connecting portion4conducts with a connecting portion on a vehicle in a state where battery pack1is installed in a mounting slot on the vehicle.

FIG.2is a diagram schematically illustrating configuration elements related to impact detection of battery pack1in a state where battery pack1according to the exemplary embodiment is mounted on vehicle5. In battery pack1, relay RY1is provided on a current path connecting a positive-electrode terminal and a negative-electrode terminal of battery module2, and positive-electrode terminal + and negative-electrode terminal − of connecting portion4.

Vehicle5includes inverter51, motor52, and vehicle controller53. Inverter51converts DC power supplied from battery pack1into AC power, and supplies it to motor52at the time of power running. At the time of regeneration, AC power supplied from motor52is converted into DC power to be supplied to battery pack1. Motor52is a three-phase AC motor, and rotates in accordance with the AC power supplied from inverter51at the time of power running. At the time of regeneration, a rotational energy due to deceleration is converted into AC power to be supplied to inverter51. Vehicle controller53is a vehicle electronic control unit (ECU) that controls entire vehicle5. Vehicle controller53can receive an abnormality signal of battery module2from impact detection device10in battery pack1.

Impact detection device10in battery pack1includes three-axis accelerometer sensor11and impact detection circuit12. Impact detection circuit12includes analog circuit unit13and digital circuit unit14.

FIG.3is a diagram illustrating a configuration example of impact detection device10in battery pack1according to the exemplary embodiment. Three-axis accelerometer sensor11detects acceleration applied to the sensor on three axes, and outputs electric signals corresponding to the detected acceleration on three channels. As three-axis accelerometer sensor11, for example, a micro electro mechanical system (MEMS) type accelerometer sensor or a piezoelectric element type accelerometer sensor can be used. Depending on the form of an accelerometer sensor such as a piezoelectric element type, accelerometer sensors, each of which detects acceleration in each of the three axes, are combined and used as three-axis accelerometer sensor11.

Analog circuit unit13of impact detection circuit12includes X-axis detector131x, X-axis peak determination unit132x, X-axis integrator134x, X-axis energy determination unit135x, Y-axis detector131y, Y-axis peak determination unit132y, Y-axis integrator134y, Y-axis energy determination unit135y, Z-axis detector131z, Z-axis peak determination unit132z, Z-axis integrator134z, and Z-axis energy determination unit135zas main configuration elements.

Digital circuit unit14includes micro-processing unit (MPU)141and non-volatile memory142. For example, an electrically erasable programmable read-only memory) (EEPROM) or a flash memory can be used as non-volatile memory142.

Hereinafter, as three-axis accelerometer sensor11, an example of using a three-axis accelerometer sensor that changes by +0.05 V or by −0.05 V with respect to a change per 1 G in a positive or negative direction with a center value of 2.5 V for each of the X-axis, Y-axis, and Z-axis will be described. Note that a power source voltage of analog circuit unit13is 5 V.

X-axis detector131xacquires an output value of three-axis accelerometer sensor11and converts an acceleration component (±0.05 V/G) of the output value of three-axis accelerometer sensor11into an absolute value (2.5 V+|±0.05 V/G|), and outputs the absolute value. X-axis peak determination unit132xcompares an output value of X-axis detector131xwith X-axis peak threshold THpx, and when the output value of X-axis detector131xexceeds X-axis peak threshold THpx, a significant signal (high level signal) is output, and when it does not exceed, a non-significant signal (low level signal) is output. For example, if an unacceptable acceleration value is set to 7 G, peak threshold THpx is set to 2.85 V (=2.5+0.05×7). Buffer133xtemporarily holds the output value of X-axis detector131x.

The output value of X-axis detector131xis converted into a pulse signal, and output to X-axis integrator134x. X-axis integrator134xintegrates the output value of X-axis detector131xand integrates an energy value of battery pack1in an X-axis for a certain period of time. X-axis integrator134xintegrates the energy value in the X-axis for a predetermined period of time when battery pack1receives an impact. Note that X-axis integrator134xhas a discharge path for discharging a capacitor, and an output value of the X-axis integrator134xis reset at regular intervals. In addition, the output value of X-axis integrator134xis reset every time MPU141is activated and impact strength determination is executed with two reference values of a peak value and an energy amount of impact acceleration by MPU141described later.

X-axis energy determination unit135xcompares the output value of X-axis integrator134xwith X-axis energy threshold THex, and when the output value of X-axis integrator134xexceeds X-axis energy threshold THex, a significant signal (high level signal) is output, and when it does not exceed, a non-significant signal (low level signal) is output. For example, if an unacceptable impact energy value integrated on the X-axis in 1.0 second is set to 20 G, energy threshold THex is set to, for example, 3.5 V (=2.5+0.05×20). Buffer136xtemporarily holds the output value of X-axis integrator134x.

X-axis AND circuit137xoutputs the logical product of an output of X-axis peak determination unit132xand an output of X-axis energy determination unit135x. That is, X-axis AND circuit137xoutputs a high level signal when the output value of X-axis detector131xexceeds X-axis peak threshold THpx and the output value of X-axis integrator134xexceeds X-axis energy threshold THex, and outputs a low level signal otherwise.

The same configuration elements as X-axis detector131x, X-axis peak determination unit132x, buffer133x, X-axis integrator134x, X-axis energy determination unit135x, buffer136x, and X-axis AND circuit137xdescribed above are also provided on the Y-axis and the-Z axis, respectively.

X-axis peak threshold THpx, Y-axis peak threshold THpy, and Z-axis peak threshold THpz are set to different values according to the mechanical characteristics of battery pack1. Furthermore, X-axis energy threshold THex, Y-axis energy threshold THey, and Z-axis energy threshold THez are also set to different values according to the mechanical characteristics of battery pack1. For example, a drop test of battery pack1is performed in advance, and a peak threshold and an energy threshold for separating an impact within an allowable range and an impact outside the allowable range are derived in each of the three axis. The impact within the allowable range is an impact within the safety guarantee range of a battery manufacturer, and continued use of battery pack1is allowed. The impact outside the allowable range is an impact outside the safety guarantee range of the battery manufacturer, and continued use of battery pack1is prohibited. In this case, battery pack1needs to be discarded or repaired. Alternatively, the safety of battery pack1is verified, and the disposal, repair, or continuation of use of battery pack1is determined according to a result of this verification. X-axis peak threshold THpx, Y-axis peak threshold THpy and Z-axis peak threshold THpz, and X-axis energy threshold THex, Y-axis energy threshold THey and Z-axis energy threshold THez are set with a margin at a boundary of the safety guarantee range based on the impact within the allowable range, so that it is assumed that battery pack1can be used continuously even if it is judged that the impact is outside the allowable range. Note that, even when at least one threshold of X-axis peak threshold THpx, Y-axis peak threshold THpy, and Z-axis peak threshold THpz is set to a value different from the other thresholds, it corresponds to setting X-axis peak threshold THpx, Y-axis peak threshold THpy, and Z-axis peak threshold THpz to different values. Also, when at least one threshold of X-axis energy threshold THex, Y-axis energy threshold THey, and Z-axis energy threshold THez is set to a value different from the other thresholds, it corresponds to setting X-axis energy threshold THex, Y-axis energy threshold THey, and Z-axis energy threshold THez to different values.

FIG.4is a diagram schematically illustrating a wound cylindrical cell. The cylindrical cell is produced by stacking and winding sheet-shaped positive electrode material, negative electrode material, and separator that separates the positive and negative electrode materials. The cylindrical cell has a property that it is relatively vulnerable to an impact in a direction (direction along Z-axis inFIG.4) along a winding axis and relatively strong against an impact in a direction (direction along X-axis and direction along Y-axis inFIG.4) perpendicular to the winding axis. Therefore, in the wound cylindrical cell, Z-axis thresholds THpz and THez are set to values smaller in absolute value than X-axis thresholds THpx and THex and Y-axis thresholds THpy and THey. Note that the same consideration applies when a wound prismatic cell is used.

FIG.5is a diagram schematically illustrating a laminated cell. The laminated cell is produced by laminating a sheet-shaped positive electrode material, separator, negative electrode material, and separator in order. The laminated cell has a property that it is relatively strong against an impact in a direction (direction along Y-axis inFIG.5) along a lamination direction and relatively vulnerable to an impact in a direction (direction along X-axis and direction along Z-axis inFIG.5) perpendicular to the lamination direction. Therefore, in the laminated cell, Y-axis thresholds THpy and THey are set to values larger in absolute value than X-axis thresholds THpx and THex and Z-axis thresholds THpz and THez. Note that the same consideration applies when a laminated prismatic cell is used.

The description returns toFIG.3. OR circuit138outputs the logical sum of an output of X-axis AND circuit137x, an output of Y-axis AND circuit137y, and an output of Z-axis AND circuit137zto a start terminal of MPU141. When an impact exceeding the thresholds is detected on at least one of X-axis, Y-axis, and Z-axis, OR circuit138outputs a high level signal to the start terminal of MPU141. OR circuit138outputs a low level signal to the start terminal of MPU141in a state where an impact exceeding the thresholds is not detected in all X-axis, Y-axis, and Z-axis.

Electric Power is supplied to analog circuit unit13and digital circuit unit14from battery module2. Analog circuit unit13is always in operation. On the other hand, digital circuit unit14is normally stopped in order to suppress power consumption. MPU141is normally controlled to shut down, sleep or stand by. MPU141starts when a signal level of the start terminal changes from a low level to a high level. When MPU141is started, the output value of X-axis detector131x, the output value of X-axis integrator134x, the output value of Y-axis detector131y, the output value of Y-axis integrator134y, the output value of Z-axis detector131z, and the output value of Z-axis integrator134zheld in buffers133x,136x,133y,136y,133z,136z, respectively, are captured internally.

Buffers133x,136x,133y,136y,133z,136zare responsible for holding the time from when an impact outside the allowable range is detected until MPU141is started, and the output value of X-axis detector131x, the output value of X-axis integrator134x, the output value of Y-axis detector131y, the output value of Y-axis integrator134y, the output value of Z-axis detector131z, and the output value of Z-axis integrator134zat the time of impact detection. The output value of X-axis detector131xat the time of impact detection shows a peak value of the impact acceleration along the X-axis, and the output value of X-axis integrator134xat the time of impact detection shows an energy amount of the impact acceleration along the X-axis. The same applies to the Y-axis and the Z-axis.

MPU141records the captured output value of X-axis detector131x, output value of X-axis integrator134x, output value of Y-axis detector131y, output value of Y-axis integrator134y, output value of Z-axis detector131z, output value of Z-axis integrator134zin non-volatile memory142. The data recorded in non-volatile memory142will be used for impact analysis at a later date.

In addition, MPU141opens (offs) relay RY1when the signal level of the start terminal changes from a low level to a high level, and prohibits charging and discharging of battery module2. Further, when battery pack1is mounted on vehicle5, MPU141transmits an abnormality signal of battery module2to vehicle controller53.

The impact detection processing by impact detection device10described above is executed in a state where battery pack1is not mounted on vehicle5. When battery pack1is mounted on vehicle5, the impact detection processing by impact detection device10may be stopped. For example, if vehicle5is provided with an impact detection function for vehicle5, it is less necessary to separately execute the impact detection processing in battery pack1. Note that, if vehicle5does not have an impact detection function for vehicle5, the above-mentioned impact detection processing is executed in battery pack1.

As described above, according to the present exemplary embodiment, it is possible to, with low power consumption, detect an impact outside the allowable range for battery pack1with high accuracy. In the present exemplary embodiment, three-axis accelerometer sensor11is used, and the threshold of each axis is set to a different value according to the mechanical characteristics. When acceleration is detected by three-axis accelerometer sensor11, an impact strength is determined based on the two reference values of the peak value of the impact acceleration and the time period (energy amount) during which the impact acceleration is applied. When impact acceleration exceeding the threshold is detected on at least one axis, MPU141is activated. MPU141stores the peak value and the amount of energy of the impact acceleration in non-volatile memory142for each axis. MPU141also performs safety control such as relay cuts.

When the impact acceleration exceeding the thresholds is not detected, MPU141is controlled to a shutdown state, a sleep state or a standby state, so that the power consumption of MPU141can be suppressed. When the impact acceleration exceeding the thresholds is detected, the above-mentioned safety control is executed, so that it is possible to prevent battery pack1from being used in an unsafe state. In the case of battery pack1, even if it seems that there is no abnormality in appearance, there may be an abnormality in internal battery module2.

Since the impact strength is determined based on the two reference values of the peak value and the amount of energy of the impact acceleration, it is possible to activate MPU141by an impact within the allowable range and prevent unnecessary safety control from being activated. Furthermore, since the determination is made on the three axes, the mechanical characteristics of battery pack1can be considered in detail, and whether or not an impact is within the allowable range can be determined with high accuracy. In addition, since the determination is made on the three axes, it is possible to prevent MPU141from being unnecessarily started due to acceleration generated by the transportation of battery pack1or an impact within the allowable range.

FIG.6is a diagram illustrating a configuration example of an impact detection device in a battery pack according to an exemplary embodiment different from the impact detection device in the battery pack illustrated inFIG.3. An impact detection device illustrated inFIG.6includes X-axis OR circuit139xthat outputs the logical sum of the output of X-axis peak determination unit132xand the output of X-axis energy determination unit135xinstead of X-axis AND circuit137x, Y-axis OR circuit139ythat outputs the logical sum of the output of Y-axis peak determination unit132yand the output of Y-axis energy determination unit135yinstead of Y-axis AND circuit137y, and Z-axis OR circuit139zthat outputs the logical sum of the output of Z-axis peak determination unit132zand the output of Z-axis energy determination unit135zinstead of Z-axis AND circuit137z. Note that, inFIG.6, the same configuration elements as those illustrated inFIG.3are given the same reference marks.

X-axis OR circuit139xoutputs the logical sum of the output of X-axis peak determination unit132xand the output of X-axis energy determination unit135x. That is, X-axis OR circuit139xoutputs a high level signal when the output value of X-axis detector131xexceeds X-axis peak threshold THpx or the output value of X-axis integrator134xexceeds X-axis energy threshold THex, and outputs low level signal otherwise.

Similarly, Y-axis OR circuit139youtputs a high level signal when the output value of Y-axis detector131yexceeds Y-axis peak threshold THpy or the output value of Y-axis integrator134yexceeds Y-axis energy threshold THey, and outputs a low level signal otherwise. Z-axis OR circuit139zoutputs a high level signal when the output value of Z-axis detector131zexceeds Z-axis peak threshold THpz or the output value of Z-axis integrator134zexceeds Z-axis energy threshold THez, and outputs a low level signal otherwise.

OR circuit138outputs the logical sum of an output of X-axis OR circuit139x, an output of Y-axis OR circuit139y, and an output of Z-axis OR circuit139zto the start terminal of MPU141. Therefore, OR circuit138outputs a high level signal to the start terminal of MPU141when impact acceleration exceeding at least one of X-axis peak threshold THpx, Y-axis peak threshold THpy and Z-axis peak threshold THpz, and X-axis energy threshold THex, Y-axis energy threshold THey and Z-axis energy threshold THez is detected. Therefore, MPU141was started, and using the peak values of the impact acceleration of each axis of X, Y, Z based on each output value held in each buffer133x,133y,133z, and the energy amount of the impact acceleration of each axis of X, Y, Z based on each output value held in each buffer136x,136y,136z, MPU141determines whether the impact is within the allowable range or outside the allowable range for continued use of battery pack1.

The present disclosure is described above according to the exemplary embodiments. It is understood by a person of ordinary skill in the art that the exemplary embodiments are merely an example, other modified examples in which configuration elements and processing processes of the exemplary embodiments are variously combined are possible, and the other modifications still fall within the scope of the present disclosure.

In the above-described exemplary embodiments, an example in which a lithium-ion battery is used for cell C1is assumed, but a capacitor such as an electric double layer capacitor can also be used. Similar to batteries, capacitors are also available in cylindrical, square, and laminated types, each with different mechanical characteristics.

Further, in the above-described exemplary embodiments, an example of performing a drop impact determination based on the two reference values of the peak value and the energy amount of the impact acceleration has been described. In this regard, the drop impact determination may be performed only by the peak value of the impact acceleration. In this case, integrators134, energy determination units135, buffers136, and AND circuits137illustrated inFIG.3become unnecessary. According to this, the cost of impact detection circuit12can be reduced.

Further, in the above-described exemplary embodiments, it is determined whether or not the impact is outside the allowable range by the AND condition of the comparison result between the two detection values of the peak value and the amount of energy of the impact acceleration, and the two thresholds. In this regard, it may be determined whether or not the impact is outside the allowable range based on an OR condition of the two comparison results. In this case, the design emphasizes safety.

Further, in the above-described exemplary embodiments, battery pack1to be mounted on vehicle5has been described. In this respect, battery pack1may be battery pack1to be mounted on an electronic device. For example, battery pack1to be mounted on a notebook PC may be used. In a state of being mounted on the notebook PC, the impact detection processing by impact detection device10in battery pack1is stopped, and the impact detection processing is executed in a state of being separated from the notebook PC.

Note that the exemplary embodiments may be specified by the following items.

Item 1

Impact detection device (10) to be mounted on power storage pack (1), device (10) including:three-axis accelerometer sensor (11); andimpact detection circuit (12) that compares detection values of three axes output from three-axis accelerometer sensor (11) with thresholds set to different values according to mechanical characteristics of power storage pack (1), and detects an impact outside an allowable range.

According to this, the impact outside the allowable range for power storage pack (1) can be detected with high accuracy.

Item 2

Impact detection device (10) according to the item 1, whereinpower storage pack (1) includes wound cylindrical cells (C1) or prismatic cells (C1), anda threshold of an axis in a direction along a winding axis is set to a value smaller in absolute value than thresholds of other two axes.

According to this, it is possible to detect the impact outside the allowable range for power storage pack (1) using wound cylindrical cells (C1) or prismatic cells (C1) with high accuracy.

Item 3

Impact detection device (10) according to the item 1, whereinpower storage pack (1) includes laminated prismatic cells (C1) or laminated cells (C1), anda threshold of an axis in a direction along a lamination direction is set to a value larger in absolute value than thresholds of other two axes.

According to this, it is possible to detect the impact outside the allowable range for power storage pack (1) using laminated prismatic cells (C1) or laminated cells (C1) with high accuracy.

Item 4

Impact detection device (10) according to any one of the items 1 to 3, whereinimpact detection circuit (12) includes:analog circuit unit (13) that is always in operation; anddigital circuit unit (14) that is normally stopped, andanalog circuit unit (13) activates processor (141) in digital circuit unit (14) when axes of which detection values exceed the thresholds are detected.

According to this, it is possible to, with low power consumption, detect the impact outside the allowable range for power storage pack (1) with high accuracy.

Item 5

Impact detection device (10) according to any one of the items 1 to 3, whereinimpact detection circuit (12) includes:first determination units (132x,132y,132z) that determine whether or not the detection values of the three axes exceed peak thresholds of the three axes, respectively;three integrators (134x,134y,134z) into which the detection values of the three axes are input, respectively; andsecond determination units (135x,135y,135z) that determine whether or not output values of three integrators (134x,134y,134z) exceed energy thresholds of the three axes, respectively, andwhen axes occur on which the detection values exceed the peak thresholds and the output values of the integrators exceed the energy thresholds, it is determined that the impact outside the allowable range has been applied.

According to this, it is possible to detect the impact outside the allowable range for power storage pack (1) with high accuracy by using the peak values and the amounts of energy.

Item 6

Impact detection device (10) according to the item 5, whereinimpact detection circuit (12) includes:analog circuit unit (13) that is always in operation; anddigital circuit unit (14) that is normally stopped,analog circuit unit (13) includes:first determination units (132x,132y,132z);integrators (134x,134y,134z); andsecond determination units (135x,135y,135z), andwhen axes occur on which the detection values exceed the peak thresholds and the output values of the integrators exceed the energy thresholds, first determination units (132x,132y,132z) and second determination units (135x,135y,135z) activate processor (141) in digital circuit unit (14).

According to this, it is possible to, with low power consumption, detect the impact outside the allowable range for power storage pack (1) with high accuracy.

Item 7

Impact detection device (10) according to any one of the items 1 to 4, whereinimpact detection circuit (12) includes three integrators (134x,134y,134z) that integrate the detection values of the three axes for a certain period of time, respectively, and it is determined that the impact outside the allowable range has been applied based on the detection values of the three axes and the output values of the integrators.

According to this, it is possible to detect the impact outside the allowable range for power storage pack (1) with high accuracy by using the peak values and the amounts of energy.

Item 8

Impact detection device (10) according to the item 7, whereinimpact detection circuit (12) includes:analog circuit unit (13) that is always in operation; anddigital circuit unit (14) that is normally stopped,analog circuit unit (13) includes:first determination units (132x,132y,132z) that determine whether or not the detection values of the three axes exceed peak thresholds of the three axes, respectively; andsecond determination units (135x,135y,135z) that determine whether or not the output values of the three integrators (134x,134y,134z) exceed energy thresholds of the three axes, respectively, andwhen at least one of the detection values exceeding the peak thresholds and the output values of the integrators exceeding the energy thresholds is detected, first determination units (132x,132y,132z) and second determination units (135x,135y,135z) activate processor (141) in digital circuit unit (14).

According to this, it is possible to, with low power consumption, detect the impact outside the allowable range for power storage pack (1) with high accuracy.

Item 9

Impact detection device (10) according to any one of the items 4, 6 and 8, wherein processor (141) prohibits charging and discharging of a plurality of cells (C1) when it is detected that the impact outside the allowable range has been applied.

According to this, the safety of power storage pack (1) can be ensured.

Item 10

Impact detection device (10) according to any one of the items 1 to 9, wherein impact detection device (10) stops impact detection processing when power storage pack (1) is mounted on power supply target device (5).

According to this, it is possible to, with low power consumption, detect the impact outside the allowable range for power storage pack (1) with high accuracy.

Item 11

Power storage pack (1) including:a plurality of cells (C1); andimpact detection device (10) according to any one of the items 1 to 10.

According to this, it is possible to realize power storage pack (1) capable of detecting the impact outside the allowable range for power storage pack (1) with high accuracy.

REFERENCE MARKS IN THE DRAWINGS

1battery pack2battery moduleC1cell3control substrate4connecting portion10impact detection device5vehicle51inverter52motor53vehicle controllerRY1relay11three-axis accelerometer sensor12impact detection circuit13analog circuit unit131xX-axis detector132xX-axis peak determination unit133xbuffer134xX-axis integrator135xX-axis energy determination unit136xbuffer137xX-axis AND circuit139xX-axis OR circuit131yY-axis detector132yY-axis peak determination unit133ybuffer134yY-axis integrator135yY-axis energy determination unit136ybuffer137yY-axis AND circuit139yY-axis OR circuit131zZ-axis detector132zZ-axis peak determination unit133zbuffer134zZ-axis integrator135zZ-axis energy determination unit136zbuffer137zZ-axis AND circuit139zZ-axis OR circuit138OR circuit14digital circuit unit141MPU142non-volatile memory