阅读说明：本技术 计测装置、蓄电装置、计测系统、偏移误差的计测方法 (Measurement device, power storage device, measurement system, and offset error measurement method ) 是由 今中佑树 高井诚治 井村雅行 于 2018-12-04 设计创作，主要内容包括：一种经由第1开关(40)与连接负载的端子部(22P)连接的电化学元件(30)的计测装置(50),具备：电流限制部(75),设置在所述第1开关(40)的旁路路径(BP)；电流传感器(60),计测所述电化学元件(30)的电流；和处理部(100),所述电流限制部(75)在所述电化学元件(30)的电压与所述端子部(22P)的电压的电压差ΔV为给定值以上的情况下,容许通过所述旁路路径(BP)向所述负载的电力供给,在电压差ΔV小于给定值的情况下,将所述旁路路径(BP)设为无电流,所述处理部(100)在所述第1开关(40)断开后,直到由于与所述负载并联连接的充放电元件(170)的放电所引起的所述端子部(22P)的电压变化而所述电压差ΔV成为给定值为止的期间,进行计测所述电流传感器(60)的偏移误差ε的计测处理。(A measurement device (50) for an electrochemical element (30) connected to a terminal portion (22P) to which a load is connected via a 1 st switch (40), comprising: a current limiting unit (75) provided on a Bypass Path (BP) of the 1 st switch (40); a current sensor (60) for measuring the current of the electrochemical element (30); and a processing unit (100) that allows power supply to the load through the Bypass Path (BP) when a voltage difference Δ V between the voltage of the electrochemical element (30) and the voltage of the terminal unit (22P) is a predetermined value or more, and that sets the Bypass Path (BP) to no current when the voltage difference Δ V is less than the predetermined value, wherein the processing unit (100) performs a measurement process of measuring an offset error of the current sensor (60) until the voltage difference Δ V becomes the predetermined value due to a voltage change of the terminal unit (22P) caused by discharge of a charge/discharge element (170) connected in parallel with the load after the 1 st switch (40) is turned off.)

1. A measuring device for measuring a current of an electrochemical element connected to a terminal portion connected to a load via a 1 st switch,

the measurement device is provided with:

a current limiting unit provided in a bypass path of the 1 st switch;

a current sensor for measuring a current of the electrochemical element; and

a processing part for processing the received signal,

the current limiting unit allows power to be supplied to the load through the bypass path when a voltage difference between the voltage of the electrochemical element and the voltage of the terminal unit is a predetermined value or more, and sets the bypass path to a no-current state when the voltage difference is less than the predetermined value,

the processing unit performs a measurement process of measuring an offset error of the current sensor until the voltage difference becomes a predetermined value due to a voltage change of the terminal unit caused by discharge of a charge/discharge element connected in parallel to the load after the 1 st switch is turned off.

2. The measurement device according to claim 1,

the electrochemical element is an electric storage element that supplies electric power to a vehicle load that does not allow power supply interruption,

the processing unit switches the 1 st switch from on to off during the parking of the vehicle to execute the measurement process.

3. The measurement device according to claim 1 or 2, wherein,

the measurement device includes: and a 2 nd switch provided in the bypass path and connected in series to the current limiting unit.

4. A measuring device according to any one of claims 1 to 3,

the current limiting portion is a diode.

5. An electrical storage device, comprising:

an electric storage element as an electrochemical element;

an accommodating body accommodating the electric storage element;

a terminal portion provided in the accommodating body and connected to a load;

a 1 st switch accommodated in the accommodating body and provided between the electric storage element and the terminal portion; and

a measuring device according to any one of claims 1 to 4, accommodated in the accommodating body.

6. The power storage device according to claim 5,

the power storage device includes: and a charge/discharge element accommodated in the accommodating body and connected to the terminal portion.

7. The power storage device according to claim 6,

the electrical storage device is used for a vehicle,

the charge/discharge element discharges a vehicle load for which power supply interruption is not permitted while the processing unit performs the measurement processing.

8. A measurement system is provided with:

an electrochemical element; and

a measuring apparatus according to any one of claims 1 to 4.

9. A method for measuring an offset error of a current sensor, wherein,

after disconnecting the 1 st switch connecting the terminal part and the electrochemical element, performing discharge from a charge/discharge element connected in parallel to a load connected to the terminal part to the load,

the current limiting unit provided in the bypass path sets the bypass path to be currentless until a voltage difference between the voltage of the electric storage element and the voltage of the terminal unit becomes a predetermined value, and measures an offset error of the current sensor.

Technical Field

The present invention relates to a technique for detecting an offset error of a current sensor.

Background

As described in patent document 1 below, a battery mounted in a vehicle estimates SOC by integrating currents detected by current sensors.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-83256

Disclosure of Invention

Problems to be solved by the invention

Even when the true value is zero, the current sensor has an offset error indicating a value other than zero. By detecting the measurement value of the current sensor in a state where the current is cut off, the offset error can be corrected. However, if the current is cut off to measure the offset error, the power supply to the load is interrupted.

The present invention has been made in view of the above-described situation, and an object thereof is to measure an offset error of a current sensor while maintaining power supply to a load.

Means for solving the problems

A measurement device for measuring a current of an electrochemical element connected to a terminal portion connected to a load via a 1 st switch, includes: a current limiting unit provided in a bypass path of the 1 st switch; a current sensor for measuring a current of the electrochemical element; and a processing unit that allows power supply to the load through the bypass path when a voltage difference between a voltage of the electrochemical element and a voltage of the terminal portion is a predetermined value or more, and sets the bypass path to no current when the voltage difference is smaller than the predetermined value, wherein the processing unit performs a measurement process of measuring an offset error of the current sensor until the voltage difference becomes the predetermined value due to a voltage change of the terminal portion caused by discharge of a charge/discharge element connected in parallel to the load after the 1 st switch is turned off.

The above-described technique can be applied to a power storage device, a measurement system, and a method of measuring an offset error. The present invention can be implemented in various ways, such as an offset error measurement program and a recording medium on which the program is recorded.

Effects of the invention

According to one aspect of the present invention, it is possible to measure an offset error while maintaining power supply to a load.

Drawings

Fig. 1 is a side view of an automobile in embodiment 1.

Fig. 2 is a perspective view of the battery.

Fig. 3 is an exploded perspective view of the battery.

Fig. 4 is a block diagram showing an electrical structure of the battery.

Fig. 5 is a diagram showing a current path to the vehicle ECU immediately after the 1 st switch is turned off.

Fig. 6 is a diagram showing a current path to the vehicle ECU when the diode is turned on.

Fig. 7 is a diagram showing a current path to the vehicle ECU when the diode reaches the forward voltage.

Fig. 8 is a graph showing current waveforms and voltage waveforms.

Fig. 9 is an enlarged view of a part of fig. 8.

Fig. 10 is a flowchart showing a flow of the offset error measurement flow.

Fig. 11 is a block diagram showing another embodiment of the battery.

Fig. 12 is a block diagram showing another embodiment of the battery.

Fig. 13 is a block diagram showing another embodiment of the battery.

Fig. 14 is a block diagram showing another embodiment of the battery.

Detailed Description

A measuring device for measuring a current of an electrochemical element connected to a terminal portion connected to a load via a 1 st switch, the measuring device comprising: a current limiting unit provided in a bypass path of the 1 st switch; a current sensor for measuring a current of the electrochemical element; and a processing unit that allows power supply to the load through the bypass path when a voltage difference between a voltage of the electrochemical element and a voltage of the terminal portion is a predetermined value or more, and sets the bypass path to no current when the voltage difference is smaller than the predetermined value, wherein the processing unit performs a measurement process of measuring an offset error of the current sensor until the voltage difference becomes the predetermined value due to a voltage change of the terminal portion caused by discharge of a charge/discharge element connected in parallel to the load after the 1 st switch is turned off.

In this configuration, when the 1 st switch is switched from on to off, the main path is not on, and the current from the electrochemical element to the load is cut off. When the current from the electrochemical element is cut off, the charge/discharge elements connected in parallel are discharged, and a current flows through the load. When the charge/discharge element discharges, the voltage at the terminal changes. The bypass path is rendered currentless by the current limiter until a voltage difference between the terminal portion and the electrochemical element reaches a predetermined value. Therefore, the offset error of the current sensor can be detected while the bypass path is currentless. When the voltage difference from the electric storage element reaches a predetermined value, the current limiting section permits the supply of electric power to the load through the bypass path. Therefore, the supply of electric power from the electrochemical element to the load can be realized by the bypass path.

In this configuration, even when the 1 st switch is switched from on to off to cut off the main path, the power supply path from the electrochemical element to the load is not cut off because the bypass path is provided. During the offset error measurement period, the bypass path is no current, and therefore the charge/discharge element discharges to the load. Therefore, the offset error can be measured without power failure (power cut to the load).

The electrochemical element is an electric storage element that supplies electric power to a vehicle load that does not allow power supply interruption, and the processing unit switches the 1 st switch from on to off during stoppage of the vehicle and executes the measurement processing.

A vehicle load request having high relevance to the safety of a vehicle, such as an engine starter, a starter of a drive system for EV, an electronic control device such as a vehicle ECU, and accessories for operating a drive unit (an engine and a main drive motor for EV), is required not only to prevent a power failure during driving and parking but also to prevent a power failure during parking. That is, it is required that the power supply is not allowed to be cut off (that is, power is always supplied) regardless of the state of the vehicle. In the present configuration, the offset error can be measured without causing a power failure with respect to such a vehicle load that does not allow power shutoff, and therefore, it is possible to respond to a request for ensuring safety.

In this configuration, the offset error is measured during parking in which the vehicle is less likely to be a dangerous event than during traveling or parking. By measuring the offset error during parking, it is not necessary to measure the offset error during traveling or parking, and therefore high safety of the vehicle can be ensured. Further, the current flowing through the vehicle load is small during parking as compared with during traveling and parking. Therefore, the current limiter having a small rated capacity can be used.

The 2 nd switch may be provided in the bypass path in series with the current limiter. In this configuration, the bypass path can be cut off by turning off the 2 nd switch when the offset error is not measured. By cutting off the current during non-measurement, it is possible to prevent a failure of the current limiting section, and therefore it is possible to improve the measurement accuracy of the offset error.

The current limiter is preferably a diode. In the case of a diode, the current limiting element is suitable because it can be switched between conducting and non-conducting according to the voltage difference. The voltage difference between both ends of the diode is detected to determine conduction and non-conduction, and the offset error can be accurately measured by performing measurement processing during the non-conduction period.

< embodiment 1>

1. Description of the storage batteries

Fig. 1 is a side view of an automobile, fig. 2 is a perspective view of a battery, fig. 3 is an exploded perspective view of the battery, and fig. 4 is a block diagram showing an electrical structure of the battery.

The vehicle 1 as the upper-level system is an engine-driven vehicle equipped with an engine. As shown in fig. 1, the automobile 1 includes a battery 20 as a power storage device. As shown in fig. 2, the battery 20 has a block-shaped battery case 21, and the battery pack 30 and the circuit board 28, which are composed of a plurality of secondary batteries B1 to B4, are housed in the battery case 21. Battery case 21 corresponds to the "housing body" of the present invention.

As shown in fig. 3, battery case 21 includes: a box-shaped case main body 23 opened at the upper side, a positioning member 24 for positioning the plurality of secondary batteries B1 to B4, an intermediate lid 25 attached to the upper portion of the case main body 23, and an upper lid 26. As shown in fig. 3, a plurality of cell compartments 23A that individually accommodate the respective secondary batteries B1 to B4 are arranged in the X direction in the case main body 23.

As shown in fig. 3, the positioning member 24 has a plurality of bus bars 27 disposed on the upper surface thereof, and the positioning member 24 is disposed above the plurality of secondary batteries B1 to B4 disposed in the case main body 23, so that the plurality of secondary batteries B1 to B4 are positioned and connected in series by the plurality of bus bars 27.

As shown in fig. 2, the middle cover 25 has a substantially rectangular shape in plan view. A pair of terminal portions 22P and 22N to which a harness terminal, not shown, is connected are provided at both ends of the middle cover 25 in the X direction. The pair of terminal portions 22P and 22N are made of metal such as lead alloy, for example, and the terminal portion 22P is a positive-side terminal portion and the terminal portion 22N is a negative-side terminal portion.

An accommodating portion 25A is provided on the upper surface of the middle cover 25. The circuit board 28 is accommodated inside the accommodating portion 25A of the middle cover 25, and the secondary battery B and the circuit board 28 are connected by being mounted on the case main body 23 through the middle cover 25. The upper cover 26 is attached to the upper portion of the middle cover 25, and covers the upper surface of the accommodating portion 25A in which the circuit board 28 is accommodated.

The electrical structure of the battery 20 will be described with reference to fig. 4. The battery 20 is a 12V system for a vehicle, and includes a battery pack 30, a 1 st switch 40, and a measurement device 50.

The assembled battery 30 is composed of 4 lithium ion secondary batteries B1 to B4 connected in series. The lithium-ion secondary batteries B1 to B4 are examples of the "electrochemical element (power storage element)" of the present invention.

The positive electrode of the battery pack 30 is connected to the positive-side terminal portion 22P via the 1 st switch 40. The negative electrode of the battery pack 30 is connected to the negative-side terminal portion 22N via a current detection resistor 61. Reference numeral 35P denotes a positive-side current-carrying circuit of the battery pack 30, and reference numeral 35N denotes a negative-side current-carrying circuit of the battery pack 30.

The 1 st switch 40 is a switch for cutting off the current of the battery pack 30, and may be composed of a relay, an FET, or the like. The 1 st switch 40 is disposed on the circuit board 28 so as to be housed in the battery case 21.

The measurement device 50 is an overall device for measuring the current of the battery pack 30, and includes a current sensor 60, a parallel circuit 70, and a processing unit 100. The measurement device 50 is disposed in the vicinity of the circuit board 28 or the circuit board 28 and is housed in the battery case 21.

The current sensor 60 is composed of a current detection resistor 61 and an AFE (Analog Front End) 65. The current detection resistor 61 is disposed inside the battery case 21 in the current-carrying circuit 35N on the negative electrode side of the battery pack 30. The current detection resistor 61 is disposed on the circuit board 28 or in the vicinity of the circuit board 28.

The AFE65 detects the voltage across the current detection resistor 61 and changes the voltage from an analog value to a digital value. The AFE65 is connected to the processing unit 100 via a signal line. The AFE60 is disposed on the circuit board 28.

The parallel circuit 70 is provided on the bypass path BP of the 1 st switch 40 and connected in parallel to the 1 st switch 40. The parallel circuit 70 is composed of a 2 nd switch 71 and a diode 75. The FET71 and the diode 75 are connected in series. The parallel circuit 70 is provided on the circuit substrate 28.

The 2 nd switch 71 is a P-channel field effect transistor, and has a source connected to the positive electrode of the battery pack 30 and a drain connected to the anode of the diode 75. The diode 75 has the discharge direction of the battery pack 30 set to the positive direction, the anode connected to the drain of the 2 nd switch 71, and the cathode connected to the positive-side terminal portion 22P. Reference numeral 90 shown in fig. 4 denotes a drive circuit 90 that drives the 2 nd switch 71.

The processing unit 100 includes a Central Processing Unit (CPU) 101 having an arithmetic function, a memory 103, a ROM105, a communication unit 107, and the like, and is disposed on the circuit board 28.

The CPU101 sends commands to the 1 st switch 40 and the 2 nd switch 71 to control the 1 st switch 40 and the 2 nd switch 71 to be turned on and off. "on" means off (closed circuit) and "off" means on (open circuit).

The CPU101 performs processing of detecting the current I of the lithium-ion secondary batteries B1 to B4 based on the output of the AFE65, and processing of estimating the SOCs of the lithium-ion secondary batteries B1 to B4 based on the detected current I.

The SOC (state of charge) is a ratio of the remaining capacity to the full charge capacity, and is represented by the following expression (1). The SOC can be estimated based on the time-integrated value of the current I as shown in the following expression (2). The sign of the current is positive during charging, and negative during discharging.

SOC＝Cr/Co×100 (1)

Co is the full charge capacity of the secondary battery, and Cr is the residual capacity of the secondary battery.

SOC＝SOCo+100×∫Idt/Co (2)

SOCo is the initial value of SOC, and I is the current.

The ROM105 stores a program for estimating the SOC and a program for executing an offset error measurement routine (S10 to S60 shown in fig. 10). The program can be stored in a recording medium such as a CD-ROM and can be transferred. The program can also be distributed using an electrical communication line.

The communication Unit 107 is provided for communication with a vehicle ECU (Electronic Control Unit) 150 mounted on the automobile 1. Vehicle ECU150 is a vehicle load that does not allow power supply shutoff regardless of the state of the vehicle during traveling, parking, or parking. After being mounted on the vehicle, communication unit 107 is connected to vehicle ECU150 via a signal line, and processing unit 100 can receive information about the vehicle such as the operating state (stop, drive) of the engine from vehicle ECU 150.

As shown in fig. 4, vehicle ECU150 is connected to battery 20 via power supply lines 135P and 135N, and electric power is supplied from battery 20 to vehicle ECU 150. Vehicle ECU150 is provided with a capacitor 170. Capacitor 170 is interposed between positive power supply line 135P and negative power supply line 135N, and is connected in parallel to vehicle ECU 150. Capacitor 170 is provided to stabilize the power supply voltage of vehicle ECU 150. Capacitor 170 functions to supply electric power by discharging to vehicle ECU150 while the offset error of current sensor 60 is measured. The capacitor 170 corresponds to the "charge/discharge element" of the present invention.

The battery 20 includes lithium ion secondary batteries B1 to B4, a battery case 21 for housing the lithium ion secondary batteries B1 to B4, a 1 st switch 40, and a measurement device 50, and thus corresponds to the "power storage device" of the present invention. The battery pack 30 and the measurement device 50 in the battery 20 correspond to the "measurement system" of the present invention.

2. Offset error and correction of current sensor 60

Even when the true value is zero, the current sensor 60 has an offset error indicating a value other than zero. By detecting the measurement value (output value of the AFE 65) of the current sensor 60 in a state where the current I of the battery pack 30 is cut off, the offset error can be measured. However, if current I is cut off to measure the offset error, the supply of electric power to vehicle ECU150 is interrupted.

In this structure, the first step 1After the switch 40 is opened, the capacitor 170 discharges. By the discharge, the voltage of the capacitor 170 decreases, and thus the voltage V2 of the terminal portion 22P decreases. A period T until a voltage difference Δ V between the voltage V2 of the terminal portion 22P and the voltage V1 of the positive electrode of the battery pack 30 reaches a predetermined value Vx₂₃Diode 75 is non-conducting. During the period T when the diode 75 is non-conductive₂₃Focusing on the case where the current I of the battery pack 30 is cut off, the offset error of the current sensor 60 is measured.

First, the processing unit 100 controls the 1 st switch 40 to be in the on state and the 2 nd switch 71 to be in the off state during normal operation (non-measurement of offset error), and thereby, as shown in fig. 4, a current flows from the battery pack 30 to the vehicle ECU150 through the main path L1 passing through the 1 st switch 40.

The capacitor 170 connected in parallel with the vehicle ECU150 is charged, and the voltage V2 of the terminal portion 22P on the positive side of the battery 20 becomes equal to the voltage V1 on the positive side of the battery pack 30 (V2 is equal to V1).

When measuring the offset error, the processing unit 100 first switches the 2 nd switch 71 from off to on (at time t1 shown in fig. 8), and then switches the 1 st switch 40 from on to off (at time t2 shown in fig. 8). The 2 nd switch 71 may be turned on at least at the time of measurement of the offset error, or may be always turned on.

"I" shown in FIG. 8₁"indicates the current flowing through main path L1," I₂"indicates the current discharged by the capacitor 170," I₃"indicates the current flowing through current path L3". I₁₃Is "is₁"and" I₃"is a discharge current from battery pack 30 to vehicle ECU 150.

At time t2, when the 1 st switch 40 is switched from on to off, the main path L1 is cut off, and the capacitor 170 starts discharging, and therefore, the vehicle ECU150 discharges current from the capacitor 170 through the current path L2 shown in fig. 5, and the voltage of the capacitor 170 drops due to the discharge, and therefore, after the 1 st switch 40 is switched, as shown in fig. 8 and 9, the voltage V2 of the terminal portion 22P on the positive side of the battery 20 drops, and a voltage difference Δ is generated between the voltage V1 on the positive side of the battery pack 30.

ΔV＝V1-V2 (3)

At time t3 shown in fig. 8 and 9, if the voltage difference Δ reaches the predetermined value V_X(0.55V, as an example), diode 75 is turned on, and when diode 75 is turned on, electric power supply to vehicle ECU150 through bypass path BP is permitted, as shown in fig. 6, current flows to vehicle ECU150 through current path L2 using capacitor 170 as a power source and current path L3 passing through parallel circuit 70 (bypass path BP) from battery pack 30.

After the diode 75 is turned on, the current flowing through the current path L3 increases and the current L2 flowing through the current path L2 decreases as the voltage difference Δ V increases, in the example of fig. 8, at a time t4 when the voltage difference Δ V reaches the forward voltage Vf of the diode 75 (0.6V as an example), the current of the current path L2 becomes zero, and thereafter, the electric power is supplied to the vehicle ECU150 through the current path L3 via the diode 75.

A period T after the 1 st switch 40 is switched off at time T2 until the diode 75 is turned on at time T3₂₃Diode 75 is non-conductive and there is no current output from battery pack 30. By during this period T₂₃By detecting the measurement value of the current sensor 60 (the output of the AFE 65), the offset error of the current sensor 60 can be measured.

Diode 75 is turned on when voltage difference Δ V is equal to or greater than predetermined value Vx, allows power to be supplied to vehicle ECU150 through bypass path BP, is turned off when voltage difference Δ V is smaller than predetermined value Vx, and sets bypass path BP to no current. Therefore, the diode 75 corresponds to the "current limiter" of the present invention.

Fig. 10 is a diagram showing a flow of the offset error measurement routine. The measurement flow includes 6 steps S10 to S60. Before the execution of the metering flow, the CPU101 controls the 1 st switch 40 to be on and the 2 nd switch 71 to be off.

The CPU101 first determines whether the vehicle 1 mounted with the battery 20 is parked (S10). Determination during parking can be made in accordance with the state of communication with vehicle ECU 150. That is, when vehicle 1 is traveling or parked, vehicle ECU150 and processing unit 100 communicate with each other frequently at a predetermined cycle.

On the other hand, when vehicle 1 is parked, vehicle ECU150 stops communication. Therefore, when the communication with the vehicle ECU100 is interrupted for a predetermined period, it can be determined that the vehicle 1 is parked.

If it is determined that the vehicle 1 is parked (S10: YES), the CPU101 then performs a process of switching the 2 nd switch 71 from OFF to ON and then switching the 1 st switch 40 from ON to OFF (S20, S30).

Next, the CPU101 turns off the 1 st switch 40 and turns on the diode 75 for a period T₂₃Then, a measurement process for measuring an offset error of the current sensor 60 is performed, and the measured offset error is stored in the memory 103 (S40). Period T₂₃The time period can be determined from the capacity of the capacitor 170, the discharge current of the capacitor 170, the voltage difference Vx across the diode 75, and the like. Experimental values can also be used.

Next, the CPU101 performs a process of switching the 1 st switch 40 from off to on, and then performs a process of switching the 2 nd switch 71 from on to off (S50, S60). As a result, the offset error measurement routine is completed.

As shown in the following expression (4), the CPU101 performs a process of correcting the measured value of the offset error correction current sensor 60 at the time of measuring the current of the lithium ion secondary batteries B1 to B4.

In this way, the measurement accuracy of the current I can be improved, and the SOC of the lithium ion secondary batteries B1 to B4 can be estimated with good accuracy.

It＝Io- (4)

It is a corrected current value, I_oThe current value before correction is an offset error. In equation (4), the charge direction is positive and the discharge direction is negative with respect to the sign of the current or offset error.

In fig. 10, the offset error measurement routine is preferably repeatedly executed at predetermined intervals, for example, at intervals of one week, and the offset error is updated to the latest value. In this way, even if the offset error changes due to a temperature change or the like, the influence thereof can be reduced, and the accuracy of measuring the current I and the accuracy of estimating the SOC can be further improved.

The parallel circuit 70 can be used as a diagnosis circuit for the closing failure of the 1 st switch 40. That is, when the 1 st switch 40 is switched from on to off in a state where the 2 nd switch 71 of the parallel circuit 70 is turned on, if the 1 st switch 40 normally operates, the voltage Δ V (V1-V2) across the 1 st switch 40 becomes the forward voltage V of the diode 75_F. On the other hand, when the 1 st switch 40 is fixed to be off, the end-to-end voltage Δ V becomes zero. Therefore, by detecting the end-to-end voltage Δ V of the 1 st switch 40, it is possible to diagnose whether or not the 1 st switch 40 has a closing failure.

4. Description of the effects

In this configuration, even if the 1 st switch 40 is switched from on to off to cut off the main path L1, the bypass path BP is provided, and therefore the power supply path from the assembled battery 30 to the vehicle ECU150 is not cut off, and the diode 75 of the bypass path BP is rendered non-conductive during the offset error measurement period, and the current I of the assembled battery 30 is temporarily cut off₂₃Capacitor 170 discharges to vehicle ECU150, and if diode 75 conducts, current I can then be supplied from battery pack 30 via bypass path BP. Therefore, the offset error can be measured while maintaining the supply of electric power to vehicle ECU150 that does not allow the power supply to be cut off. In the present configuration, the offset error can be measured without causing a power failure with respect to such a vehicle load that does not allow power shutoff, and therefore, it is possible to respond to a demand for ensuring safety.

During parking, in which the vehicle 1 is less likely to fall into a dangerous event than during traveling or parking, the processing unit 100 switches the 1 st switch 40 from on to off, and measures the offset error of the current sensor 60. By measuring the offset error during parking, it is not necessary to measure the offset error during traveling or parking, and therefore high safety of the vehicle can be ensured. In addition, vehicle ECU150 consumes less current than during traveling or parking, and the current flowing through diode 75 when conducting is small. Therefore, the diode 75 having a small rated capacity can be used.

In this configuration, the offset error is not measured (T)₂₃Other periods), the CPU101 controls the 2 nd switch 71 to be off. By turning off the 2 nd switch 71, the bypass path BP can be cut off. By cutting off the current during non-measurement, it is possible to prevent a failure of the diode 75 as the current limiter, and therefore it is possible to improve the accuracy of measuring the offset error. When there is an abnormality in the battery pack 30 such as overdischarge, the current flowing through the bypass path BP can be cut off by turning off the 2 nd switch 71.

< other embodiment >

The present invention is not limited to the embodiments described above and illustrated in the drawings, and for example, the following embodiments are also included in the technical scope of the present invention.

(1) Embodiment 1 illustrates a measuring device 50 for measuring the current of the lithium ion secondary batteries B1 to B4. The present technology is only required to be a measuring device for measuring a current, and can be widely applied to electrochemical devices other than the lithium ion secondary batteries B1 to B4. The electrochemical device includes an electric storage device such as a secondary battery or an electric double layer capacitor, a primary battery that performs only discharge, a fuel cell, a solar cell, and the like. In embodiment 1, a plurality of lithium ion secondary batteries B1 to B4 are connected in series as an example, but a single battery may be used.

(2) Embodiment 1 shows an example in which a battery 20 as a power storage device is mounted on an engine-driven vehicle. The use of the battery 20 is not limited to the engine-driven vehicle. The present invention may be mounted in an electric vehicle or a hybrid electric vehicle. The present technology can be applied to power storage devices for aircraft, ships, and railways, as well as vehicles. In particular, it is preferably used for a load that does not allow power supply interruption, but may be used for a load that partially allows power supply interruption.

(3) In embodiment 1, electric power is supplied from battery pack 30 to vehicle ECU150, but the supply target of electric power (vehicle load) is not limited to vehicle ECU 150. Other vehicle loads that do not allow power supply interruption, such as a starter motor for driving the engine and accessories of the engine, may be used.

(4) In embodiment 1, the 1 st switch 40 and the parallel circuit 70 are provided on the positive side of the battery pack 30, and the current sensor 60 is provided on the negative side of the battery pack 30. The configuration may be reversed, and the 1 st switch 40 and the parallel circuit 70 may be disposed on the negative electrode side of the battery pack 30, while the current sensor 60 may be disposed on the positive electrode side of the battery pack 30. When the 1 st switch 40 and the parallel circuit 70 are provided on the negative electrode, if the 1 st switch 40 is turned off, the voltage of the terminal portion 22N changes due to the discharge of the capacitor 170, and a voltage difference Δ V is generated between the negative electrode-side terminal portion 22N and the negative electrode of the battery pack 30. Since the diode 75 is non-conductive until the generated voltage difference Δ V reaches the predetermined value Vx, the offset error of the current sensor 60 can be measured during this period. When the 1 st switch 40 and the parallel circuit 70 are provided on the negative electrode side, the voltage of the terminal portion 22N becomes higher than the negative electrode of the battery pack 30 due to the discharge of the capacitor 170. Therefore, the diode 75 has an anode connected to the terminal portion 22N and a cathode connected to the negative electrode of the battery pack 30, and the discharge direction is set to the forward direction.

(5) In embodiment 1, the capacitor 170 is provided outside the battery, the capacitor 170 may be provided in the battery, the battery 200 shown in fig. 11 is provided with the capacitor 270 inside the battery case 21, one end of the capacitor 270 is connected to the positive-side terminal portion 22P, and the other end is connected to the negative-side terminal portion 22N, the capacitor 270 is charged by the battery pack 30, when the 1 st switch 40 is turned off to cut off the main path L1, the capacitor 270 is discharged to supply electric power to the vehicle ECU150, and the capacitor 270 is discharged until a period T until a voltage difference Δ V between a positive-electrode voltage V1 and a positive-electrode terminal portion V2 of the battery pack 30 reaches a predetermined value Vx₂₃The diode 75 is not energized, and the bypass path BP is currentless. Therefore, during the period T₂₃The offset error of the current sensor 60 can be measured by the processing unit 100. In this structure, the battery 20 is providedSince capacitor 270 is incorporated, even when capacitor 170 is not provided on the vehicle 1 side, the offset error of current sensor 60 can be measured while power is continuously supplied to vehicle load 150. The capacitor 270 built in the battery 20 is subjected to the offset error measurement process in the processing unit 100 for a period T₂₃And acts to discharge the vehicle load 150.

(6) The capacitors 170 and 270 may be discharged when the 1 st switch 40 is turned off, and may be replaced with a charge/discharge element such as a secondary battery, for example.

(7) Embodiment 1 shows a diode 75 as an example of the current limiter. The current limiting unit may be a member other than a diode as long as it allows power supply to the load through the bypass path BP when the voltage difference Δ V between the voltage V1 of the battery pack 30 and the voltage V2 of the terminal unit 22P is equal to or greater than the predetermined value Vx, and when the voltage difference Δ V is smaller than the predetermined value, the bypass path BP is set to be currentless. In battery 300 shown in fig. 12, FET310 connected by a diode constitutes a current limiter. The diode connection is a connection that shorts the gate and the source. The diode-connected FET310 is conductive when the voltage difference is equal to or greater than a predetermined value, and is non-conductive except that it is, similarly to the diode 75, so that it can replace the diode 75. The battery 300 of fig. 12 disables the 2 nd switch 71.

(8) Battery 400 shown in fig. 13 includes current limiting unit 410 including 3 rd switch 420 and comparator 430. The comparator 430 detects a voltage difference Δ V between a voltage V1 of the positive electrode of the battery pack 30 and a voltage V2 of the positive-side terminal portion 22P. The comparator 430 outputs a signal for turning on the 3 rd switch 420 when the voltage difference Δ V is equal to or greater than a predetermined value, and outputs a signal for turning off the 3 rd switch 420 when the voltage difference Δ V is less than the predetermined value. Even when the current limiting unit 410 is configured by the 3 rd switch 420 and the comparator 430, the 3 rd switch 420 is turned off and the bypass path BP is set to a non-current state during a period after the 1 st switch 40 is turned off until the voltage difference Δ V reaches the predetermined value, and therefore, the offset error of the current sensor 60 can be measured during this period. When the current limiting unit 410 is configured by the 3 rd switch 420 and the comparator 430, there is an advantage that a threshold value (voltage difference) at which the bypass path BP is switched from the non-energized state (3 rd switch: off) to the energized state (3 rd switch: on) can be arbitrarily set.

(9) Battery 500 shown in fig. 14 uses buck regulator 510 as a current limiting unit. The step-down regulator 510 steps down and outputs an input voltage (voltage V1 of the battery pack). The bypass path BP is set to no current when the voltage V2 of the positive terminal portion 22P is higher than the output voltage V3 of the step-down regulator 510. Therefore, after the 1 st switch 40 is turned off, the offset error of the current sensor 60 can be measured until the voltage V2 of the terminal portion on the positive electrode side drops from the voltage V1 of the positive electrode of the battery pack 30 to the output voltage V3 of the step-down regulator 510 due to the discharge of the capacitor 170. When the voltage V2 of the terminal portion 22P drops to the output voltage V3, the voltage V2 of the terminal portion 22P is maintained at the output voltage V3 of the step-down regulator 510, and electric power can be supplied to the vehicle load 150 via the bypass path BP.

(10) In embodiment 1, the period T from the time when the 1 st switch 40 is switched off to the time when the diode 75 is turned on is obtained from the capacity of the capacitor 170, the discharge current of the capacitor 170, the voltage difference Vx at which the diode 75 is turned on, and the like₂₃. The diode 75 is non-conductive when a voltage difference Δ V between the voltage V2 of the terminal portion 22P and the voltage V1 of the positive electrode of the battery pack 30 is smaller than a given value Vx, and is conductive when the given value Vx is reached. Therefore, after the 1 st switch 40 is switched off, the voltage V2 of the terminal 22P and the voltage V1 of the positive electrode of the battery pack 30 are detected to obtain the voltage difference Δ V, and the offset error may be measured until the obtained voltage difference Δ V reaches the predetermined value Vx. In this way, since the measurement can be performed while the diode 75 is not energized, the accuracy of the measurement of the offset error is improved. Even when the step-down regulator 510 is used as the current limiting unit, the voltage V2 of the terminal 22P is detected and compared with the output voltage V3 of the step-down regulator, whereby the currentless period of the bypass path BP can be determined.

(11) In embodiment 1, whether or not vehicle 1 is parked is determined based on the state of communication with vehicle ECU150, but may be determined based on the magnitude of current I of battery pack 30. That is, when the state where the current I is equal to or less than the predetermined value continues for a certain time, it may be determined that the vehicle is stopped. Alternatively, the determination may be made based on the presence or absence of vibration for a predetermined time or longer. The detection of the vibration may also be performed by a sensor.

(12) In embodiment 1, correction processing for correcting the current I of the lithium ion secondary batteries B1 to B4 based on the offset error is performed. In addition, the SOC may be corrected without correcting the current I. Specifically, the SOC error (SOC error due to the offset error of current sensor 60) may be corrected based on the accumulated time of current I for calculating the SOC and the offset error.

(13) The measuring device 50 may be configured to include the current sensor 60, the parallel circuit 70, and the processing unit 100, and these members 60, 70, and 80 are not necessarily provided in the battery. In embodiment 1, the configuration in which the 1 st switch 40 and the parallel circuit 70 are provided inside the battery 20 is exemplified. The 1 st switch 40 and the parallel circuit 70 may be mounted on the vehicle, or may be provided outside the battery 20. Similarly, the current sensor 60 and the processing unit 100 may be mounted on the vehicle, or may be provided outside the battery 20. That is, battery 20 may be configured to include only lithium ion secondary batteries B1 to B4, and processing unit 100 provided outside the battery may acquire period T from current sensor 60 provided outside the battery₂₃The offset error is measured from the measured value data.

(14) The measurement system may be any system that includes an electrochemical element such as the assembled battery 30 and the measurement device 50 and measures the current of the electrochemical element 30 by the measurement device 50. The physical configuration such as where the electrochemical element 30 and the measuring device 50 are disposed may be any configuration.

(15) The technique disclosed in embodiment 1 can be implemented in various forms such as a program for measuring an offset error of a current sensor and a recording medium on which the program is recorded.

One measurement program is a measurement program for measuring an offset error of the current sensor 60, and causes the computer 40 to execute the following measurement processing (S40): at the connecting terminal part 22PAnd a period T until the current limiting element 75 provided in the bypass path BP of the 1 st switch 40 sets the bypass path BP to no current after the 1 st switch 40 of the electrochemical element 30 is turned off₂₃And an offset error of the current sensor 60 is measured.

Description of the symbols

1, a vehicle;

20 storage batteries (corresponding to "power storage device" of the present invention);

30 battery packs;

40, a 1 st switch;

60 current sensors;

61 current detection resistance;

65 AFE；

70 a parallel circuit;

71 a 2 nd switch;

a 75 diode (corresponding to a "current limiter" of the present invention);

100 a processing unit;

101 CPU；

150 vehicle ECU (equivalent to "vehicle load" of the invention);

170 a capacitor (corresponding to the "charge/discharge element" of the present invention);

b1 to B4 lithium ion secondary batteries (corresponding to the "electrochemical device (storage device)" of the present invention).