JP7052706B2 - Temperature monitoring system - Google Patents

Description

The present disclosure relates to a temperature monitoring system, and more specifically to a temperature monitoring system for monitoring the temperature of a power storage device.

Vehicles such as hybrid vehicles or electric vehicles equipped with a power storage device for traveling (battery pack, etc.) are becoming widespread. These vehicles are generally equipped with a monitoring device that monitors the temperature of the power storage device. For example, Japanese Patent Application Laid-Open No. 2009-109271 (Patent Document 1) discloses an apparatus configuration for detecting the temperature of a plurality of cells by a plurality of temperature sensors (more specifically, a thermistor).

Japanese Unexamined Patent Publication No. 2009-109271 Japanese Unexamined Patent Publication No. 2018-42368

An abnormal temperature rise may occur in the power storage device. In order to appropriately protect the power storage device and suppress the excessive progress of deterioration of the power storage device, it is desirable to determine the presence or absence of such a temperature rise by a monitoring device.

In recent years, since the distance that a vehicle can travel (so-called EV mileage) is lengthened by the electric power stored in the power storage device, the power storage device tends to be large in size. As the size of the power storage device increases, the wiring (wire harness) of the temperature sensor provided in the power storage device becomes long, so that noise is likely to be superimposed on the wiring. When the noise superimposed on the wiring propagates to the temperature sensor, the temperature sensor may generate heat due to the electrical resistance of the temperature sensor. Then, there is a possibility that an erroneous determination that an abnormal temperature rise has occurred may occur even though the abnormal temperature rise of the power storage device has not actually occurred.

The present disclosure has been made to solve the above-mentioned problems, and an object thereof is to improve the accuracy of determining whether or not an abnormal temperature rise of a power storage device has occurred.

A temperature monitoring system according to an aspect of the present disclosure is configured to be electrically connected to a pair of wires extending from a temperature sensor whose electrical resistance changes according to the temperature of the power storage device, and monitors the temperature of the power storage device. do. A temperature monitoring system in which a high potential line that is electrically connectable to one of a pair of wires and is maintained at a predetermined potential and a high potential line that is electrically connectable to the other of a pair of wires are configured to be electrically connectable and have a reference potential. It is equipped with a low potential line maintained at. The current path connecting the high potential line to the pair of wires and the low potential line includes first and second paths having different resonance frequencies. The temperature monitoring system consists of a switching device configured to switch between the first path and the second path, a control device for controlling the switching device, and a high potential line and a low potential determined according to the electrical resistance of the temperature sensor. The temperature of the power storage device is calculated from the voltage detected by the voltage detector and the voltage detector that detects the voltage between the wires, and whether or not an abnormal temperature rise has occurred in the power storage device based on the calculated temperature. It is further provided with a determination device for determining.

When the temperature of the power storage device exceeds a predetermined temperature while the current path is one of the first and second paths, the control device sets the current path to the other of the first and second paths. Control the switching device so that it can be switched. The determination device determines that an abnormal temperature rise has occurred in the power storage device when the temperature of the power storage device is maintained above the predetermined temperature even after the current path is switched.

In the above configuration, when the temperature of the power storage device exceeds the predetermined temperature while the current path is one of the first and second paths, the current path is the other of the first and second paths. Can be switched to. Since the first path and the second path have different resonance frequencies from each other, even if noise is superimposed in one of the above states, it is suppressed that noise is superimposed in the other state. Therefore, when the temperature rise of the power storage device is due to noise superposition, no further temperature rise occurs after the current path is switched, and the temperature of the power storage device drops. Therefore, according to the above configuration, it is determined that an abnormal temperature rise has occurred in the power storage device when the temperature of the power storage device is maintained above the predetermined temperature even after the current path is switched, so that the power storage device is abnormal. It is possible to improve the accuracy of determining whether or not a temperature rise has occurred.

According to the present disclosure, it is possible to improve the accuracy of determining whether or not an abnormal temperature rise of the power storage device has occurred.

It is a block diagram which shows the whole composition of a vehicle schematicly. It is a figure which shows the structure of the temperature monitoring system and the battery pack in the comparative example. It is the first figure for demonstrating the heat generation mechanism of a temperature sensor. It is a 2nd figure for demonstrating the heat generation mechanism of a temperature sensor. It is a circuit block diagram which shows the structure of the temperature monitoring system and the battery pack in this embodiment. It is a figure for demonstrating the monitoring process in this embodiment. It is a flowchart which shows the monitoring process in this embodiment. It is a circuit block diagram which shows the structure of the temperature monitoring system and the battery pack in the modification.

Hereinafter, the present embodiment will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals, and the description thereof will not be repeated.

[Embodiment]
<Vehicle configuration>
FIG. 1 is a block diagram schematically showing an overall configuration of a vehicle. With reference to FIG. 1, the vehicle 100 is, for example, a hybrid vehicle, which includes a temperature monitoring system 1, a battery pack 2, a power control unit (PCU) 3, motor generators 4 and 5, and an engine. A power dividing device 7, a drive shaft 8, a drive wheel 9, and a vehicle control unit (ECU) 10 are provided.

The temperature monitoring system 1 monitors the temperature of the battery pack 2. The temperature monitoring system 1 includes a monitoring unit 11 and a battery ECU 12. The monitoring unit 11 detects the temperature of the battery pack 2 and outputs the detection result to the battery ECU 12. The configuration of the monitoring unit 11 will be described later.

Although not shown, the battery ECU 12 includes a CPU (Central Processing Unit), a memory, and input / output ports to which various signals are input / output. The battery ECU 12 (CPU) executes various processes related to the battery pack 2 based on the signals received from each sensor and the programs and maps stored in the memory. A main process executed by the battery ECU 12 is a process (monitoring process) for monitoring the presence or absence of an abnormality in the battery pack 2. The monitoring process will also be described in detail later. In the present embodiment, the battery ECU 12 corresponds to both the “control device” and the “determination device” according to the present disclosure. However, the "control device" and the "determination device" according to the present disclosure may be configured by separate ECUs.

The battery pack 2 stores electric power for driving the motor generators 4 and 5, and supplies electric power to the motor generators 4 and 5 through the PCU3. Further, the battery pack 2 is charged by receiving the generated power through the PCU 3 when the motor generators 4 and 5 generate power. The battery pack 2 includes an assembled battery (storage device) 21 and a temperature sensor 22. The configuration of the battery pack 2 will be described with reference to FIG. Instead of the assembled battery 21, a capacitor such as an electric double layer capacitor may be provided.

The PCU 3 executes bidirectional power conversion between the battery pack 2 and the motor generators 4 and 5 according to the control signal from the vehicle ECU 10. The PCU 3 is configured so that the states of the motor generators 4 and 5 can be controlled separately. For example, the motor generator 5 can be put into a power running state while the motor generator 4 is in a regenerative state (power generation state). The PCU 3 includes, for example, two inverters provided corresponding to the motor generators 4 and 5 and a converter (neither shown) that boosts the DC voltage supplied to each inverter to a voltage higher than the output voltage of the battery pack 2. Consists of including.

Each of the motor generators 4 and 5 is an AC rotary electric machine, for example, a three-phase AC synchronous electric machine in which a permanent magnet (not shown) is embedded in a rotor. The motor generator 4 is mainly used as a generator driven by the engine 6 via the power dividing device 7. The electric power generated by the motor generator 4 is supplied to the motor generator 5 or the battery pack 2 via the PCU 3.

The motor generator 5 mainly operates as an electric motor and drives the drive wheels 9. The motor generator 5 is driven by receiving at least one of the electric power from the battery pack 2 and the electric power generated by the motor generator 4, and the driving force of the motor generator 5 is transmitted to the drive shaft 8. On the other hand, when the vehicle is braking or the acceleration is reduced on a downhill slope, the motor generator 5 operates as a generator to generate regenerative power generation. The electric power generated by the motor generator 5 is supplied to the battery pack 2 via the PCU 3.

The engine 6 is an internal combustion engine that outputs power by converting the combustion energy generated when the air-fuel mixture is burned into the kinetic energy of movers such as pistons and rotors.

The power splitting device 7 includes, for example, a planetary gear mechanism (not shown) having three rotation axes of a sun gear, a carrier, and a ring gear. The power dividing device 7 divides the power output from the engine 6 into a power for driving the motor generator 4 and a power for driving the drive wheels 9.

Like the battery ECU 12, the vehicle ECU 10 includes a CPU, a memory, and input / output ports (none of which are shown) to which various signals are input / output. The vehicle ECU 10 executes various processes for controlling the vehicle 100 to a desired state based on the signal received from each sensor and the program and the map stored in the memory. More specifically, the vehicle ECU 10 controls the motor generators 4 and 5 and controls the charging / discharging of the assembled battery 21 by controlling the PCU3. The vehicle ECU 10 can also control the engine 6. The vehicle ECU 10 and the battery ECU 12 are configured to be capable of bidirectional communication.

In FIG. 1, a configuration in which the vehicle 100 is a hybrid vehicle will be described as an example, but the vehicle 100 is not particularly limited to a hybrid vehicle as long as it is equipped with the temperature monitoring system 1 and the battery pack 2. The vehicle 100 may be an electric vehicle or a fuel cell vehicle.

<Temperature monitoring system configuration in comparative example>
In order to facilitate understanding of the features of the temperature monitoring system 1 according to the present embodiment, first, the configuration of the temperature monitoring system 1A in the comparative example will be described below.

FIG. 2 is a circuit block diagram showing the configurations of the temperature monitoring system 1A and the battery pack 2 in the comparative example. With reference to FIG. 2, the battery pack 2 includes the assembled battery 21 and the temperature sensor 22 as described above.

The assembled battery 21 includes a plurality of cells. The connection relationship between the plurality of cells in the assembled battery 21 is not particularly limited, but as an example, a module is configured by connecting a plurality of cells in series, and further, a plurality of modules are connected in parallel. Therefore, the assembled battery 21 is configured.

The temperature sensor 22 is a sensor that detects the temperature of the assembled battery 21 based on the change in electrical resistance, and is, for example, a thermistor. As the thermistor, an NTC (Negative Temperature Coefficient) thermistor can be used, but a PTC (Positive Temperature Coefficient) thermistor may also be used. Further, the temperature sensor 22 may be a thermocouple or a resistance temperature detector. Hereinafter, the temperature of the assembled battery 21 detected by using the temperature sensor 22 is also referred to as “battery temperature TB”. Further, the resistance of the temperature sensor 22 is described as "Rx".

The monitoring unit 11A includes a high potential side node NH, a low potential side node NL, a power supply line PL, a ground line GL, a resistance Ry, a capacitor C, and a voltage sensor 111.

The high potential side node NH is electrically connected to one of the pair of wire harnesses W extending from the temperature sensor 22 and the power supply line PL. The low potential side node NL is electrically connected to the other side of the wire harness W and the ground wire GL. The pair of wire harnesses W corresponds to the "pair of wiring" according to the present disclosure. The power line PL corresponds to the "high potential line" according to the present disclosure, and the ground line GL corresponds to the "low potential line" according to the present disclosure.

The resistance Ry is a pull-up resistor electrically connected between the power supply VCS that supplies a predetermined power supply voltage V (for example, 5V) to the power supply line PL and the power supply line PL. The magnitude of the resistance Ry is, for example, 10 kΩ.

The capacitor C is an ESD (Electro-Static Discharge) countermeasure capacitor electrically connected between the power supply line PL and the ground line GL. However, the capacitor C is not an essential component for detecting the temperature of the assembled battery 21.

The voltage sensor 111 is electrically connected between the power supply line PL and the ground line GL. The voltage sensor 111 detects the voltage Vx between the power supply line PL and the ground line GL, and outputs the detection result to the battery ECU 12A. The voltage sensor 111 corresponds to the "voltage detector" according to the present disclosure.

The principle of detecting the temperature (battery temperature) TB of the assembled battery 21 in the temperature monitoring system 1A will be briefly described. When the current flowing through the current path from the power supply VCS (power supply voltage V) to the ground GND via the resistance Ry, the power supply line PL, the temperature sensor 22 (resistance Rx) and the ground line GL is described as I, according to Ohm's law. The relationship shown in the following equation (1) is established.

V = (Rx + Ry) x I ... (1)
Considering the current path from the low potential side of the resistance Ry to the ground GND via the power supply line PL, the temperature sensor 22 (resistance Rx), and the ground line GL, the current flowing through this path is in the above equation (1). It is common with the current I, and the relationship shown in the following equation (2) is established.

Vx = Rx × I ・ ・ ・ (2)
When the current I is eliminated by combining the above equations (1) and (2), the following equation (3) is derived.

Vx = Rx × V / (Rx + Ry) ・ ・ ・ (3)
Since the power supply voltage V and the resistance Ry are known, the resistance Rx of the temperature sensor 22 can be calculated from the voltage Vx between the power supply line PL and the ground line GL according to the above equation (3). The battery temperature TB can be calculated from the voltage Vx by storing the correspondence relationship between the resistance Rx and the temperature (thermistor temperature characteristic) in the memory of the battery ECU 12 as a map, for example.

<Thermistor fever>
In recent years, the electric power stored in the battery pack increases the distance that the vehicle can travel (EV mileage), so that the battery pack tends to become larger. When the battery pack 2 is a large-sized battery pack, the wiring (wire harness W) of the temperature sensor 22 becomes long, so that noise is likely to be superimposed on the wire harness W. When the noise superimposed on the wire harness W propagates to the temperature sensor 22, the temperature sensor 22 may generate heat due to the resistance Rx of the temperature sensor 22.

FIG. 3 is a first diagram for explaining the heat generation mechanism of the temperature sensor 22. FIG. 3 shows the heat generation mechanism of the temperature sensor 22 due to the magnetic coupling noise. With reference to FIG. 3, the noise source 90 is a PCU 3 including, for example, an inverter and a converter (not shown), and generates AC noise that fluctuates at a constant frequency by switching control such as PWM (Pulse Width Modulation) control. The wire harness W0 extending from the noise source 90 and the pair of wire harnesses W for electrically connecting the temperature sensor 22 and the monitoring unit 11A are arranged so as to be parallel to each other.

When the AC noise generated in the noise source 90 flows through the wire harness W0, a magnetic field is generated around the wire harness W0. When the AC noise fluctuates abruptly, the magnetic field also fluctuates abruptly. Then, a current flows in a direction that cancels the change in the magnetic flux interlinking in the closed circuit region (indicated by the diagonal line) including the temperature sensor 22 and the pair of wire harnesses W (Lenz's law). Then, Joule heat is generated in the resistance Rx of the temperature sensor 22.

FIG. 4 is a second diagram for explaining the heat generation mechanism of the temperature sensor 22. FIG. 4 shows the resonance mechanism of the temperature sensor 22 due to the capacitive coupling noise. As shown in FIG. 4, a parasitic capacitance Cp may be generated between the wire harness W0 and the wire harness W arranged in parallel with each other. Then, the AC noise generated in the noise source 90 can propagate (superimpose) from the wire harness W0 to the wire harness W through the parasitic capacitance Cp. As a result, Joule heat may be generated in the resistance Rx of the temperature sensor 22.

When the temperature sensor 22 generates heat according to the mechanism described with reference to FIGS. 3 and 4, the resistance Rx of the temperature sensor 22 changes. Along with this change in resistance, there is a possibility that an erroneous determination that an abnormal temperature rise has occurred may occur even though the abnormal temperature rise of the battery pack 2 has not actually occurred.

Therefore, in the present embodiment, as described below, by providing two paths having different resonance frequencies, the AC noise from the noise source 90 creates a state in which it is difficult for the AC noise to flow in the current path, and the temperature sensor 22 in that state is created. A configuration is adopted in which the battery temperature TB is obtained from the resistance Rx of.

<Temperature monitoring system configuration in this embodiment>
FIG. 5 is a circuit block diagram showing the configurations of the temperature monitoring system 1 and the battery pack 2 according to the present embodiment. With reference to FIG. 5, the monitoring unit 11 is different from the monitoring unit 11A in the comparative example in that the inductors L1 and L2 and the switching device 112 are further included.

The inductors L1 and L2 are connected to the power supply line PL. The inductor L1 and the inductor L2 are connected in parallel with each other. The inductance of the inductor L1 and the inductance of the inductor L2 are different. It is desirable that the inductance difference between the inductor L1 and the inductor L2 is as large as possible.

In the present embodiment, the current path from the power supply VCC to the ground GND via the temperature sensor 22 includes the “first path” and the “second path”. The first path is the power supply VCS-resistance Ry-inductor L1-high potential side node NH-wire harness W (high potential side) -temperature sensor 22-wire harness W (low potential side) -low potential side node NL- Ground wire GL-A current path represented by ground GND. The second path is the power supply VCS-resistance Ry-inductor L2-high potential side node NH-wire harness W (high potential side) -temperature sensor 22-wire harness W (low potential side) -low potential side node NL- Ground wire GL-A current path represented by ground GND.

The switching device 112 includes a switching element such as a transistor, a relay, and the like. The switching device 112 is configured to be able to switch between the first path and the second path according to the control signal from the battery ECU 12.

<Monitoring process>
FIG. 6 is a diagram for explaining the monitoring process in the present embodiment. In FIGS. 6A and 6B, the horizontal axis represents the elapsed time and the vertical axis represents the battery temperature TB. FIG. 6A shows a change in the battery temperature TB when an abnormal temperature rise of the assembled battery 21 actually occurs. FIG. 6B shows a change in the battery temperature TB when the AC noise is merely superimposed on the wire harness W and the abnormal temperature rise of the assembled battery 21 does not actually occur.

With reference to FIG. 6A, at the initial time t0, the current path between the power supply VCS and the ground GND is set to, for example, the first path. The battery temperature TB starts to rise at time t1, and the battery temperature TB exceeds the predetermined temperature TB at time t2. Then, the current path is switched from the first path to the second path. When the abnormal temperature rise of the assembled battery 21 actually occurs, the battery temperature TB continues to rise thereafter, and the state in which the battery temperature TB exceeds the predetermined temperature Tc is maintained. In this case, it can be determined that an abnormal temperature rise of the assembled battery 21 has occurred.

On the other hand, as shown in FIG. 6B, when the abnormal temperature rise of the assembled battery 21 does not actually occur, when the current path is switched from the first path to the second path, The battery temperature TB drops. The reason is explained as follows.

The first path includes the inductor L1 and the second path includes the inductor L2. As described above, the inductance of the inductor L1 and the inductance of the inductor L2 are different. Therefore, the resonance frequencies of the first path and the second path are different from each other.

When the frequency of the AC noise emitted from the noise source 90 (see FIGS. 3 and 4) matches the resonance frequency of the first path, Joule heat is generated by the resistance Rx of the temperature sensor 22 during the period from time t1 to time t2. Is generated, and the battery temperature TB rises. However, the frequency of the AC noise does not match the resonance frequency of the second path. Therefore, after time t2, the AC noise superimposed on the wire harness W is significantly reduced, and the generation of Joule heat in the resistance Rx of the temperature sensor 22 is suppressed. Therefore, the battery temperature TB drops due to the cooling of the assembled battery TB (forced cooling when the assembled battery 21 is provided with a cooling mechanism (not shown)) and falls below the predetermined temperature Tc. In this case, it can be determined that the AC noise is merely superimposed on the wire harness W and that the abnormal temperature rise of the assembled battery 21 has not occurred. As described above, according to the present embodiment, it is possible to prevent an erroneous determination that an abnormal temperature rise of the assembled battery 21 has occurred.

<Monitoring flow>
FIG. 7 is a flowchart showing the monitoring process according to the present embodiment. This flowchart is, for example, called from the main routine (not shown) by the battery ECU 12 every time a predetermined cycle elapses, and is repeatedly executed. Further, each step included in this flowchart (hereinafter, the step is abbreviated as "S") is basically realized by software processing by the battery ECU 12, but dedicated hardware (electricity) manufactured in the battery ECU 12 is provided. It may be realized by a circuit). At the start of execution of this flowchart, the current path from the power supply VCS to the ground GND via the temperature sensor 22 is set to one of the first and second paths.

With reference to FIG. 7, in S1, the battery ECU 12 detects the battery temperature TB. Since this detection method has been described in detail in FIGS. 2 using the above equations (1) to (3), the description here will not be repeated.

In S2, the battery ECU 12 determines whether or not the battery temperature TB is higher than the predetermined temperature Tc. As the predetermined temperature Tc, for example, the upper limit temperature of the temperature range (normal range) when the assembled battery 21 is used as usual can be set. When the battery temperature TB is equal to or lower than the predetermined temperature Tc (NO in S2), the subsequent processing is skipped and the processing is returned to the main routine.

In S2, the battery ECU 12 advances the process to S3 when the rising speed (TB / dt) of the battery temperature TB exceeds a predetermined threshold value, and the rising speed of the battery temperature TB is below the threshold value. In some cases, the process may be returned to the main routine. More specifically, with the detection cycle of the battery temperature TB as Δt, the battery ECU 12 obtains the temperature difference (= TBnew-TBold) between the latest battery temperature TBnew and the battery temperature TBold corresponding to Δt earlier than that. It can be determined whether or not this temperature difference exceeds the threshold value. As an example, when the battery temperature TB rises from TBold = 25 ° C. to TBnew = 35 ° C. during Δt (for example, 1 second), the battery ECU 12 has a temperature difference of 10 ° C. exceeding a threshold value (for example, 8 ° C.). As a result, the process can proceed to S3. Since the temperature rise due to noise superposition often occurs suddenly, it is desirable to adopt the control based on the rise speed (temperature gradient or temperature difference) of the battery temperature TB.

When the battery temperature TB is higher than the predetermined temperature Tc (YES in S2), the battery ECU 12 changes the current path from one of the first and second paths (the path set at the start of execution of the flowchart) to the other. The switching device 112 is controlled so that the switching can be performed (S3). Then, the battery ECU 12 detects the battery temperature TB again after waiting for a predetermined time, for example (S4).

In S5, the battery ECU 12 determines whether or not the battery temperature TB detected in S4 is higher than the predetermined temperature Tc. When the battery temperature TB is higher than the predetermined temperature Tc (YES in S5), the battery ECU 12 determines that an abnormal temperature rise of the assembled battery 21 has occurred (S6). Although not shown, after that, the vehicle ECU 10 may control the PCU 3 so that the charge / discharge amount of the assembled battery 21 decreases in order to suppress the further temperature rise of the assembled battery 21. Alternatively, the vehicle ECU 10 may notify the user of an abnormality in the assembled battery 21 by, for example, turning on a warning light (not shown).

On the other hand, when the battery temperature TB is equal to or lower than the predetermined temperature Tc (NO in S5), the battery ECU 12 determines that the AC noise is only superimposed on the wire harness W and that the abnormal temperature rise of the assembled battery 21 does not occur. (S7).

As described above, in the temperature monitoring system 1 according to the present embodiment, the current path from the power supply VCC to the ground GND via the temperature sensor 22 is switched between the first path and the second path. It is possible. Since the resonance frequencies of the first path and the second path are different from each other, even if AC noise is superimposed on one of them, the overlap of AC noise is suppressed on the other. Therefore, when an increase in the battery temperature TB exceeding a predetermined temperature Tc is detected in both the first and second paths, it is determined that the battery temperature TB is actually increasing, while the first and first paths are determined. When an increase in the battery temperature TB exceeding the predetermined temperature Tc is detected only in one of the two paths, it can be determined that the increase in the battery temperature TB has not occurred. This makes it possible to improve the accuracy of determining whether or not an abnormal temperature rise occurs in the battery pack 2 (assembled battery 21).

Further, when the temperature sensor 22 is an NTC thermistor, the resistance of the temperature sensor 22 decreases as the temperature of the temperature sensor 22 becomes higher, and the current becomes easier to flow through the temperature sensor 22. As a result, an excessive current may flow through the temperature sensor 22 and the temperature sensor 22 may fail in the open mode. According to the present embodiment, control for suppressing a further increase in the battery temperature TB when it is determined that the battery temperature TB is actually increased (suppressing the charge / discharge amount of the assembled battery 21 as described above). By executing the control), it is possible to prevent the temperature sensor 22 from failing.

[Modification example]
In the embodiment, a configuration in which the resonance frequency is changed by the inductors L1 and L2 having different inductances from each other has been described. However, the element for changing the resonance frequency is not limited to the inductor, and a capacitor can also be used.

FIG. 8 is a circuit block diagram showing the configuration of the monitoring system and the battery pack 2 in the modified example. With reference to FIG. 8, in the temperature monitoring system 1B according to the present modification, the monitoring unit 11B further includes the capacitors C1 and C2 and the switching device 113, and the monitoring unit 11 according to the embodiment (see FIG. 5). ) Is different.

The capacitors C1 and C2 are electrically connected between the power supply line PL and the ground line GL via the switching device 113. The capacitor C1 and the capacitor C2 are connected in parallel with each other. The capacitance of the capacitor C1 and the capacitance of the capacitor C2 are different. It is desirable that the capacitance difference between the capacitor C1 and the capacitor C2 is as large as possible.

Like the switching device 112, the switching device 113 includes a switching element such as a transistor, a relay, and the like. The switching device 113 is configured so that one of the capacitors C1 and C2 can be selected as the capacitor electrically connected between the power supply line PL and the ground line GL according to the control signal from the battery ECU 12B. ing.

More specifically, for example, when the first path is realized by the switching control by the switching device 112, the battery ECU 12B controls the switching device 113 so that the capacitor C1 is selected from the capacitors C1 and C2. do. As a result, the capacitor C1 is electrically connected between the power supply line PL and the ground line GL. On the other hand, when the second path is realized by the switching control by the switching device 112, the battery ECU 12B controls the switching device 113 so that the capacitor C2 is selected from the capacitors C1 and C2. As a result, the capacitor C2 is electrically connected between the power supply line PL and the ground line GL.

Since the flowchart showing the monitoring process in this modification is basically the same as the flowchart showing the monitoring process in the embodiment (see FIG. 7), detailed description will not be repeated. Also in the above-described modification, the accuracy of determining whether or not an abnormal temperature rise of the assembled battery 21 has occurred can be improved, as in the embodiment.

Further, in the circuit configuration shown in FIG. 5, both the inductors L1 and L2 are not indispensable, and only one of the inductors L1 and L2 may be provided. This also causes the inductance of the first path and the inductance of the second path to be different, so that it is possible to make a difference between the resonance frequency of the first path and the resonance frequency of the second path. Is. Similarly, in the circuit configuration shown in FIG. 8, only one of the capacitors C1 and C2 may be provided.

The embodiments disclosed this time should be considered to be exemplary and not restrictive in all respects. The scope of the present disclosure is set forth by the claims rather than the description of the embodiments described above, and is intended to include all modifications within the meaning and scope of the claims.

100 vehicles, 1,1A, 1B monitoring system, 2 battery packs, 21 sets of batteries, 22 temperature sensors, 3 PCUs, 4, 5 motor generators, 6 engines, 7 power dividers, 8 drive shafts, 9 drive wheels, 10 vehicles ECU, 90 noise source, 11,11A, 11B monitoring unit, 111 voltage sensor, 112,113 switching device, 12,12A, 12B battery ECU, PL power supply line, GL ground line, NH high potential side node, NL low potential side Node, L1, L2 inductor, C, C1, C2 capacitor, Cp parasitic capacitance, Rx, Ry resistor, W0, W wire harness.

Claims (1)

A temperature monitoring system that monitors the temperature of the power storage device by being electrically connected to a pair of wires extending from a temperature sensor whose electrical resistance changes according to the temperature of the power storage device.
A high-potential line that is configured to be electrically connectable to one of the pair of wires and is maintained at a predetermined potential.
The other of the pair of wires is configured to be electrically connectable and has a low potential line maintained at a reference potential.
The current path connecting the high potential line, the pair of wirings, and the low potential line includes first and second paths having different resonance frequencies from each other.
A switching device configured to be able to switch between the first route and the second route, and
A control device that controls the switching device and
A voltage detector that detects the voltage between the high potential line and the low potential line, which is determined according to the electrical resistance of the temperature sensor.
Further provided with a determination device for calculating the temperature of the power storage device from the voltage detected by the voltage detector and determining whether or not an abnormal temperature rise has occurred in the power storage device based on the calculated temperature.
In the control device, when the temperature of the power storage device exceeds a predetermined temperature in a state where the current path is one of the first and second paths, the current path becomes the first and second paths. The switching device is controlled so that it can be switched to the other of the routes.
The determination device is a temperature monitoring system that determines that an abnormal temperature rise has occurred in the power storage device when the temperature of the power storage device is maintained above the predetermined temperature even after the current path is switched.

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