阅读说明：本技术 管理装置、蓄电系统 (Management device and power storage system ) 是由 山本贤人 黑崎雄太 于 2018-12-28 设计创作，主要内容包括：单元电压测量部(12)测量被串联连接的多个单元(E1-Em)各自的电压。总电压测量部(11)测量多个单元(E1-Em)的总电压。控制部(15)管理多个单元(E1-Em)各自的内部阻抗。控制部(15)检测由总电压测量部(11)测量到的总电压的纹波,将多个单元(E1-Em)的各单元的内部阻抗相对于合成内部阻抗的比率乘以检测出的总电压的纹波来推定各单元电压的纹波,判定各单元电压的纹波是否处于容许电压的范围内。(A cell voltage measurement unit (12) measures the voltage of each of a plurality of cells (E1-Em) connected in series. A total voltage measurement unit (11) measures the total voltage of the plurality of cells (E1-Em). A control unit (15) manages the internal impedance of each of the plurality of cells (E1-Em). A control unit (15) detects the ripple of the total voltage measured by the total voltage measurement unit (11), multiplies the ratio of the internal impedance of each of the plurality of cells (E1-Em) to the synthesized internal impedance by the ripple of the detected total voltage to estimate the ripple of each cell voltage, and determines whether the ripple of each cell voltage is within the range of the allowable voltage.)

1. A management device is provided with:

a cell voltage measuring unit that measures voltages of a plurality of cells connected in series;

a total voltage measuring unit that measures a total voltage of the plurality of cells; and

a control unit for managing internal impedance of each of the plurality of cells,

the control unit detects a ripple of the total voltage measured by the total voltage measuring unit, multiplies a ratio of an internal impedance of each of the plurality of units to a synthesized internal impedance by the ripple of the detected total voltage to estimate a ripple of each of the unit voltages, and determines whether the ripple of each of the unit voltages is within an allowable voltage range.

2. A management device is provided with:

a cell voltage measuring unit that measures voltages of a plurality of cells connected in series;

a ripple detecting section that detects ripples of cell voltages of some of the plurality of cells; and

a control unit for managing internal impedance of each of the plurality of cells,

the control unit estimates a ripple of each cell voltage based on the ripple of the voltage detected by the ripple detection unit and each internal impedance of the plurality of cells, and determines whether the ripple of each cell voltage is within an allowable voltage range.

3. The management device according to claim 2,

the ripple detection section is provided in the control section.

4. The management device according to any one of claims 1 to 3,

the control unit manages the internal impedance of each cell in a frequency band corresponding to a frequency 2 times the commercial power supply frequency.

5. The management device according to any one of claims 1 to 4,

the management device further includes:

a current measuring unit that measures currents flowing in the plurality of cells; and

a temperature measuring unit that measures temperatures of the plurality of cells,

the control unit includes a table in which characteristic data of the cell, i.e., SOHlang EN-US > state of health, SOC, i.e., state of charge, and internal impedance for each temperature are described,

the control unit determines the internal impedance of each cell with reference to the table based on the SOH, SOC, and temperature of each cell.

6. The management device according to any one of claims 1 to 4,

the management device further includes:

a current measuring unit that measures currents flowing in the plurality of cells,

the control unit estimates the internal impedance of each cell based on a voltage change of each cell before and after a predetermined current is supplied to the plurality of cells.

7. An electricity storage system is provided with:

a plurality of cells connected in series; and

the management device according to any one of claims 1 to 6, which manages the plurality of units.

Technical Field

The present invention relates to a management device and a power storage system that manage states of a plurality of cells connected in series.

Background

In recent years, the demand for secondary batteries such as lithium ion batteries and nickel hydride batteries has been expanding. Secondary batteries are used in various applications such as in-vehicle applications and stationary storage applications (e.g., backup, peak shift, fr (frequency adjustment)). In particular, in recent years, the number of shipped EVs (Electric vehicles) and PHEVs (Plug-in Hybrid Electric vehicles) has increased, and charging to EVs/PHEVs from a charger installed outside the Vehicle has increased.

Along with this, the number of cases in which low-cost and low-specification chargers are used is increasing. In a low-specification charger, a ripple component generated when alternating-current power of a commercial power supply system is rectified cannot be sufficiently removed, and a current having a large ripple component superimposed thereon flows into a secondary battery. In stationary power storage applications, a power conditioner is required to be compact and low-cost, and a current having a large ripple component superimposed thereon may flow into a secondary battery.

In an electric storage system including a plurality of cells connected in series, a voltage is measured for each cell, and whether or not the cell voltage is within an allowable voltage range is monitored (for example, see patent document 1). In the case of charging from a low-specification charger, there is a fear that the cell voltage pulsates and exceeds the allowable voltage range of the cell due to the influence of the ripple current.

Prior art documents

Patent document

Patent document 1: JP 2008-112740

Disclosure of Invention

Problems to be solved by the invention

Since the ripple of the cell voltage is a minute voltage variation, a high-precision voltage measurement circuit is required to monitor the ripple of the cell voltage with high precision. Furthermore, the cell voltage needs to be sampled at a sampling frequency that is a multiple or more of the ripple frequency. To fulfill this need, a costly and large-sized voltage measurement circuit (e.g., an analog front-end IC) is required. In particular, the larger the number of units connected in series, the larger the circuit scale, and the larger the system size and cost.

The present invention has been made in view of such circumstances, and an object thereof is to provide a technique capable of measuring a ripple of each voltage of a plurality of cells connected in series by a low-cost and small-scale circuit.

In order to solve the above problem, a management device according to an aspect of the present invention includes: a cell voltage measuring unit that measures voltages of a plurality of cells connected in series; a total voltage measuring unit that measures a total voltage of the plurality of cells; and a control unit that manages the internal impedance of each of the plurality of cells. The control unit detects a ripple of the total voltage measured by the total voltage measuring unit, multiplies a ratio of an internal impedance of each of the plurality of units to a synthesized internal impedance by the ripple of the detected total voltage to estimate a ripple of each of the unit voltages, and determines whether the ripple of each of the unit voltages is within an allowable voltage range.

According to the present invention, the ripple of each voltage of a plurality of cells connected in series can be measured by an inexpensive and small-scale circuit.

Drawings

Fig. 1 is a diagram for explaining an electric storage system according to embodiment 1 of the present invention.

Fig. 2 is a diagram showing an example of output waveforms of a charging current and a storage module voltage when charging is performed by a low-specification charger.

Fig. 3 (a) - (c) are diagrams for explaining the influence of the ripple of the charging current flowing from the low-specification charger into the cell.

Fig. 4 (a) - (b) are partial circuit diagrams showing a configuration example of the total voltage measuring unit.

Fig. 5 is a flowchart for explaining a ripple measurement method of the power storage system according to embodiment 1 of the present invention.

Fig. 6 is a flowchart for explaining a ripple measurement method of the power storage system according to embodiment 2 of the present invention.

Fig. 7 (a) - (b) are partial circuit diagrams showing a configuration example according to embodiment 3.

Detailed Description

Fig. 1 is a diagram for explaining an electric storage system 1 according to embodiment 1 of the present invention. The example shown in fig. 1 is an example in which the power storage system 1 according to the present embodiment is mounted on a vehicle as a battery for driving the vehicle. As this vehicle, an EV/PHEV chargeable from a commercial power system (hereinafter, simply referred to as system 5) is assumed.

The power storage system 1 is connected to the motor 3 via a 1 st relay SW1 and the inverter 2. The inverter 2 converts dc power supplied from the power storage system 1 into ac power during power running and supplies the ac power to the motor 3. During regeneration, ac power supplied from the electric motor 3 is converted into dc power and supplied to the power storage system 1. The motor 3 is a three-phase ac motor, and rotates in accordance with ac power supplied from the inverter 2 during power running. During regeneration, the rotational energy caused by deceleration is converted into ac power and supplied to the inverter 2.

The 1 st relay SW1 is inserted between the wirings connecting the power storage module 20 of the power storage system 1 and the inverter 2. The management device 10 of the power storage system 1 controls the 1 st relay SW1 to be in an on state (closed state) during traveling, and electrically connects the power storage module 20 and the power system of the vehicle. The management device 10 basically controls the 1 st relay SW1 to the off state (on state) to electrically block the power storage module 20 and the power system of the vehicle when the vehicle is not running. Instead of the relay, another type of switch such as a semiconductor switch may be used.

The power storage system 1 includes a power storage module 20 and a management device 10. The power storage module 20 is formed by connecting a plurality of cells E1-Em in series. As the cell, a lithium ion battery cell, a nickel hydride battery cell, a lead battery cell, an electric double layer capacitor cell, a lithium ion capacitor cell, or the like can be used. Hereinafter, in the present specification, an example using a lithium ion battery cell (nominal voltage: 3.6 to 3.7V) is assumed. The number of the cells E1-Em connected in series is determined in accordance with the drive voltage of the motor 3.

A shunt resistor Rs is connected in series with the plurality of cells E1-Em. The shunt resistor Rs functions as a current detection element. In addition, a hall element may be used instead of the shunt resistance Rs. Further, a temperature sensor T1 for detecting the temperature of the plurality of cells E1-Em may be provided. For example, a thermistor can be used for the temperature sensor T1.

The management device 10 includes a total voltage measuring unit 11, a cell voltage measuring unit 12, a temperature measuring unit 13, a current measuring unit 14, a control unit 15, and a drive unit 16. The total voltage measuring unit 11 measures the both-end voltage (total voltage) of the plurality of cells E1-Em connected in series. The configuration example of the total voltage measuring unit 11 will be described later.

The cell voltage measuring unit 12 is connected to each node of the plurality of cells E1-Em connected in series via a plurality of voltage lines, and measures the voltage of each cell E1-Em by measuring the voltage between 2 adjacent voltage lines. The cell voltage measuring unit 12 transmits the measured voltage of each cell E1-Em to the control unit 15. Since the cell voltage measuring unit 12 has a high voltage with respect to the control unit 15, the cell voltage measuring unit 12 and the control unit 15 are connected by a communication line while being insulated from each other.

The cell voltage measuring unit 12 may be formed of a general-purpose analog front end IC or an asic (application specific integrated circuit). When the small and inexpensive cell voltage measuring unit 12 is used, the cell voltage measuring unit 12 includes a multiplexer and an a/D converter. The multiplexer outputs the voltages between the adjacent 2 voltage lines to the A/D converter in sequence from the top. The A/D converter converts the analog voltage input from the multiplexer into a digital value. When the large and expensive cell voltage measuring unit 12 is used, the number of differential amplifiers corresponding to the number of cells is included in addition to the multiplexer and the a/D converter. Each differential amplifier amplifies the voltage between 2 adjacent voltage lines and outputs the amplified voltage to the multiplexer.

The temperature measuring unit 13 includes a voltage dividing resistor and an a/D converter. The a/D converter converts the voltage divided by the temperature sensor T1 and the voltage dividing resistor into a digital value and outputs the digital value to the control unit 15. The controller 15 estimates the temperatures of the cells E1-Em based on the digital values.

The current measuring unit 14 includes a differential amplifier and an a/D converter. The differential amplifier amplifies the voltage across the shunt resistor Rs and outputs the amplified voltage to the a/D converter. The a/D converter converts the voltage input from the differential amplifier into a digital value and outputs the digital value to the control unit 15. The control unit 15 estimates the currents flowing through the plurality of cells E1-Em based on the digital value.

In addition, when an a/D converter is mounted in the control unit 15 and an analog input port is provided in the control unit 15, the temperature measuring unit 13 and the current measuring unit 14 can output an analog voltage to the control unit 15 and convert the voltage into a digital value by the a/D converter in the control unit 15.

The drive unit 16 generates a drive signal for opening and closing the 1 st relay SW1 or the 2 nd relay SW2 based on a control signal from the control unit 15, and supplies the drive signal to the 1 st relay SW1 or the 2 nd relay SW 2.

The control unit 15 manages the power storage module 20 based on the total voltage, each current, and each temperature of the plurality of cells E1-Em measured by the total voltage measurement unit 11, the cell voltage measurement unit 12, the temperature measurement unit 13, and the current measurement unit 14. For example, when an overvoltage, an excessively small voltage, an overcurrent, or a temperature abnormality occurs in at least one of the cells E1-Em, the controller 15 controls the drive unit 16 to turn off the 1 st relay SW1 and/or the 2 nd relay SW2 to protect the cells E1-Em.

The control unit 15 includes an arithmetic unit 15a and an internal impedance table 15 b. The control unit 15 may be constituted by a microcomputer and a nonvolatile memory (for example, an EEPROM or a flash memory).

The arithmetic unit 15a estimates the SOC (State Of Charge) and SOH (State Of Health) Of each Of the plurality Of cells E1-Em. The SOC can be estimated by an OCV (Open Circuit Voltage) method or a current integration method. The OCV method is a method of estimating the SOC based on the OCV of each cell E1-Em measured by the cell voltage measurement unit 12 and the characteristic data of the SOC-OCV curve held by the nonvolatile memory. The current integration method is a method of estimating the SOC based on the OCV at the start of charge and discharge of each cell E1-Em measured by the cell voltage measuring unit 12 and the integrated value of the current measured by the current measuring unit 14.

SOH is defined by the ratio of the current fully charged capacitance to the initial fully charged capacitance, with degradation progressing as the value is lower (closer to 0%). The SOH may be obtained by capacitance measurement based on full charge and discharge, or may be obtained by summing the storage degradation and the cycle degradation. The storage degradation can be estimated based on the SOC, the temperature, and the storage degradation speed. Cycle degradation can be estimated based on the SOC range, temperature, current rate, and rate of cycle degradation used. The stored degradation rate and the cycle degradation rate can be derived in advance through experiments and simulations. The SOC, temperature, SOC range, and current rate can be obtained by measurement.

Further, SOH can be estimated based on a correlation with the internal resistance of the cell. The internal resistance can be estimated by dividing the voltage drop occurring when a given current flows through the cell for a given time by the current value. The internal resistance is in a relationship of decreasing as the temperature increases, and increasing as the SOH decreases. The deterioration of the cell progresses as the number of charge and discharge increases. In addition, the deterioration of the cell depends on individual differences and use environments. Therefore, as the use period becomes longer, basically, the deviation of the capacitances of the plurality of cells E1-Em becomes gradually larger.

The operation unit 15a records an operation history including the voltage, current, temperature, SOC, and SOH of each cell E1-Em in the nonvolatile memory. The internal impedance table 15b is held in the nonvolatile memory. The internal impedance table 15b is a table describing characteristic diagrams of SOH, SOC, and internal impedance for each temperature of the cells used in the power storage module 20. The characteristic map of the internal impedance can be derived based on experimental data measured while changing the conditions of SOH, SOC, and temperature, or simulation data calculated while changing the conditions.

The present embodiment is directed to measuring a ripple component corresponding to a frequency (100 Hz or 120Hz in japan) 2 times the commercial power supply frequency (50 Hz or 60Hz in japan) superimposed from the system 5, and will be described in detail later. Therefore, the characteristic diagram of the internal impedance is derived on the premise that a voltage on which a ripple component having a frequency 2 times the commercial power supply frequency is superimposed is applied to the cell. When a general-purpose system is constructed, a characteristic diagram of the internal impedance for each frequency band may be derived in advance and described in the internal impedance table 15 b.

As described above, the electrical storage system 1 can be charged from the system 5 by being connected to the charger 4 provided outside the vehicle by a charging cable. The charger 4 is provided in a home, an automobile dealer, a service area, a commercial facility, a public facility, or the like. Charger 4 is connected to system 5, and charges power storage system 1 in the vehicle via a charging cable.

In the vehicle, a 2 nd relay SW2 is inserted between the wiring connecting the power storage module 20 and the charger 4. Instead of the relay, another type of switch such as a semiconductor switch may be used. Management device 10 controls second relay SW2 to be in the on state (closed state) when charging is started, and to be in the off state (open state) when charging is completed. When an overvoltage, an undervoltage, an overcurrent, or a temperature abnormality is detected in at least one of the cells E1-Em during charging from the charger 4, the management device 10 turns off the 2 nd relay SW2 to protect the cells E1-Em.

The charger 4 full-wave rectifies the ac power supplied from the system 5 and smoothes the ac power with a filter. Since it is difficult to remove all the periodic components by the filter, a ripple component of 2 times the frequency of the commercial power supply is superimposed on the output power of the charger 4.

As described above, with the spread of EV/PHEV, low-cost and low-specification chargers are spreading. The high-specification charger is composed of two converters: a high power factor converter called a pfc (power factor correction) circuit for suppressing a higher harmonic current at the time of charging; and a DC/DC converter that removes a ripple component from an output current including a low-frequency ripple of the PFC circuit to control the charging current, so that the ripple of the output current of the charger becomes a small ripple. On the other hand, many low-specification chargers have a configuration in which a charging current is controlled by a PFC circuit. In this case, the ripple of the output current of the charger becomes a large ripple.

Fig. 2 is a diagram showing an example of output waveforms of a charging current and a storage module voltage when charging is performed by a low-specification charger. The example shown in fig. 2 is an example of a state in which the voltage of the power storage module 20 is about 48V, the charging current is about 23A, and the charging power is about 1100W. As shown in fig. 2, the ripple of the charging current becomes large. Since such an increase in the number of chargers is expected in the future, it is important to take measures against ripples on the power storage system 1 side.

Fig. 3 (a) - (c) are diagrams for explaining the influence of the ripple of the charging current flowing from the low specification charger flow to the cell. Fig. 3 (a) is a diagram showing a simple equivalent circuit of the unit E1. The unit E1 is constituted by a series circuit of the electromotive force E and the internal resistance Ri. Fig. 3 (b) shows a waveform of a charging current i flowing through the cell E1 when charging is performed from a low-specification charger. Fig. 3 (c) is a diagram showing a voltage waveform of the cell E1 when charging is performed from a low-specification charger. When the ripple of the charging current i increases, the voltage of the cell E1 also ripples due to the influence of the ripple. If the cell voltage is pulsed, the probability of exceeding the maximum allowable voltage of the cell E1 becomes high. Therefore, in order to monitor whether or not an overvoltage is applied to the cell E1, it is important to measure the ripple of the cell voltage with high accuracy. The ripple of the cell voltage is represented by the difference between the maximum voltage value and the minimum voltage value in a unit period, i.e., the peak-to-peak value. The ripple of the cell voltage may be represented by a maximum voltage value or a minimum voltage value with respect to the dc component in a unit cycle.

Since the ripple of the cell voltage is a minute voltage variation, a high-precision voltage measurement circuit is required. Furthermore, the cell voltage needs to be sampled at a sampling frequency that is 2 times or more the ripple frequency. For this reason, it is considered to mount the high-specification cell voltage measuring unit 12. However, when the high-specification cell voltage measuring unit 12 is mounted, the cost increases and the circuit scale also increases. In particular, in the vehicle-mounted application, the number of units connected in series is increased, and therefore, the system size and cost are significantly increased. Therefore, in the present embodiment, a mechanism is introduced to estimate the ripple of each cell voltage from the ripple of the total voltage of the plurality of cells E1-Em.

Fig. 4 (a) - (b) are partial circuit diagrams showing a configuration example of the total voltage measuring unit 11. In the example shown in fig. 4 (a), the total voltage measuring unit 11 includes a 1 st voltage-dividing resistor R1 and a 2 nd voltage-dividing resistor R2 connected in series. The voltage divided by the 1 st voltage dividing resistor R1 and the 2 nd voltage dividing resistor R2 is input to an analog input port of the controller 15. Further, an operational amplifier may be interposed between the voltage divider circuit and the control unit 15. The control unit 15 samples the input voltage at a sampling frequency 4 times or more the commercial power supply frequency. The control section 15 determines the maximum voltage value and the minimum voltage value in a given period and detects the ripple of the total voltage. The predetermined period is set to a period corresponding to a frequency 2 times the frequency of the commercial power supply.

In the example shown in fig. 4 (b), the total voltage measuring unit 11 includes a 1 st voltage dividing resistor R1 and a 2 nd voltage dividing resistor R2 connected in series, and a peak hold circuit 11 a. The voltage divided by the 1 st voltage dividing resistor R1 and the 2 nd voltage dividing resistor R2 is applied to the input terminal of the peak hold circuit 11 a. A general peak hold circuit using an operational amplifier, a diode, and a capacitor can be used for the peak hold circuit 11 a. By resetting the capacitor every half cycle of the ripple cycle, the peak hold circuit 11a can output the maximum voltage value or the minimum voltage value to the control section 15. In this configuration example, the control unit 15 can reduce the sampling frequency.

Fig. 5 is a flowchart for explaining a ripple measurement method of the power storage system 1 according to embodiment 1 of the present invention. The control unit 15 of the management device 10 determines the SOC, temperature, and SOH of each cell E1-Em (S10). The controller 15 refers to the internal impedance table 15b based on the SOC, temperature, and SOH of each of the cells E1-Em, and determines the internal impedance of each of the cells E1-Em (S11). The controller 15 calculates a combined internal impedance of the plurality of cells E1-Em connected in series by summing the internal impedances of the identified cells E1-Em (S12).

When the charging from the charger 4 to the power storage module 20 is started (S13), the control unit 15 detects a ripple of the total voltage based on the voltage input from the total voltage measurement unit 11 (S14). The control section 15 brings 1 as an initial value into the parameter n (S15).

The control unit 15 monitors whether or not charging is completed (S16). When the charging is completed (yes in S16), the ripple measurement process is ended. During charging (no in S16), control unit 15 calculates the ripple of the nth cell voltage using the following equation (1) (S17).

Ripple of the nth unit voltage (ripple of total voltage x) (internal impedance/synthesized impedance of nth unit) (equation 1)

The control unit 15 determines whether or not the ripple of the nth cell voltage is within the allowable voltage range of the cell (S18), and if the ripple of the nth cell voltage is outside the allowable voltage range of the cell (no in S18), the control unit 15 opens the 2 nd relay SW2 (S111), and ends the ripple measurement process. When the ripple of the nth cell voltage is within the allowable voltage range of the cell (yes at S18), the control section 15 increments the parameter n (S19). The control unit 15 compares the parameter n with the number m of series (S110), and if the parameter n is equal to or less than the number m of series (no in S110), the process proceeds to step S16. If the parameter n exceeds the number m of series connections (yes at S110), the process proceeds to step S14.

As described above, according to embodiment 1, the ripple of each cell voltage is estimated by multiplying the ripple of the total voltage by the ratio of the internal impedance of each cell of the plurality of cells to the combined internal impedance. This eliminates the need to measure the ripple of the cell voltage by the cell voltage measuring unit 12, and thus can suppress an increase in system size and an increase in cost associated with high precision of the cell voltage measuring unit 12. That is, the cell voltage measuring unit 12 of a high-specification charger that is assumed to contain almost no ripple component can be used as it is. It is sufficient that the total voltage measuring unit 11 is provided in a single unit regardless of the number of units connected in series. In this regard, when the ripple of the cell voltage is measured by the cell voltage measuring unit 12, the system size and cost increase as the number of cells connected in series increases. As described above, the ripple measurement method according to the present embodiment is a method in which the advantage is increased as the number of units connected in series is increased.

High-frequency noise superimposed on the switching power supply of charger 4 can be absorbed by connecting a capacitor to the input stage of power storage module 20. In contrast, in order to absorb low-frequency noise of 100Hz or 120Hz by a capacitor, a capacitor having a large capacitance is required, which leads to an increase in system size and an increase in cost. Therefore, it is possible to suppress the cost not by the low-frequency noise removal but by monitoring and blocking the current as needed.

Next, a ripple measurement method of the power storage system 1 according to embodiment 2 of the present invention will be described. In embodiment 2, it is not necessary to hold the internal impedance table 15b in advance in a nonvolatile memory in the control unit 15. In embodiment 2, the internal impedance of each cell E1-Em is measured before charging.

Fig. 6 is a flowchart for explaining a ripple measurement method of the power storage system 1 according to embodiment 2 of the present invention. The control unit 15 of the management device 10 instructs the charger 4 to supply the constant current to the power storage module 20 for a predetermined period before the charging from the charger 4 is started (S20). When a communication line is included in the charging cable, the control unit 15 can transmit the instruction to the charger 4 by communication using the communication line. In addition, power line communication can also be utilized. The value of the constant current is preferably set to a small value.

The controller 15 detects the voltage change of each cell E1-Em before and after the constant current is supplied from the charger 4 (S21). The controller 15 calculates the internal impedance of each cell E1-Em based on the constant current value supplied from the charger 4 and the voltage variation value of each cell E1-Em (S22). The controller 15 calculates the combined internal impedance of the plurality of cells E1-Em connected in series by summing the calculated internal impedances of the cells E1-Em (S23). Hereinafter, the processing of steps S24 to S212 is the same as the processing of steps S13 to S111 in the flowchart of fig. 5, and therefore, the description thereof is omitted.

As described above, according to embodiment 2, the same effects as those of embodiment 1 can be obtained. Further, in embodiment 2, since the internal impedance table 15b is not required, development cost can be suppressed. Further, since the internal impedance of each cell E1-Em is measured based on the constant current from the charger 4 for charging, it is possible to obtain the high-accuracy internal impedance reflecting the ripple component superimposed from the charger 4 for charging and the environmental condition.

Next, a ripple measurement method of the power storage system 1 according to embodiment 3 of the present invention will be described. In embodiment 3, instead of measuring the total voltage of the plurality of cells E1-Em to detect the ripple of the total voltage, the ripple of the cell voltage of one cell E1 is detected. The ripple of the cell voltage of one cell E2-Em is estimated by multiplying the ratio of the internal impedance of one cell E1 to the internal impedance of the other cells E2-Em by the ripple of the cell voltage of one cell E1.

Fig. 7 (a) - (b) are partial circuit diagrams showing a configuration example according to embodiment 3. In embodiment 3, the total voltage measuring unit 11 is omitted. The ripple detection unit 15c in the control unit 15 detects a ripple of the cell voltage of one cell E1. In addition, in embodiment 1 shown in fig. 4 (a) - (b), the ripple of the total voltage of the plurality of cells E1-Em is detected by the ripple detecting section 15c within the control section 15. The ripple detection unit 15c may be provided separately outside the control unit 15.

As described above, according to embodiment 3, the ripple of each unit voltage other than one is estimated by multiplying the ripple of the unit voltage of one unit by the ratio of the internal impedance of one unit to the internal impedance of each other unit. This makes it possible to measure the ripple of one cell voltage, and thus to suppress an increase in the system size and an increase in the cost of the cell voltage measuring unit 12.

The present invention has been described above based on the embodiments. The embodiments are illustrative, and various modifications may be made to the combination of these components and processes, and those skilled in the art will understand that such modifications are also within the scope of the present invention.

In the above-described embodiment, the example in which the above-described ripple measurement method is used in the power storage system 1 for the vehicle-mounted use has been described, but the above-described ripple measurement method can also be used in the power storage system 1 for the stationary-type power storage use. The ripple measurement method described above can also be used in the power storage system 1 for electronic devices such as notebook PCs and smart phones.

In addition, the embodiment can be determined by the following items.

[ item 1]

A management device (10) is characterized by comprising:

a cell voltage measurement unit (12) that measures the voltage of each of a plurality of cells (E1-Em) connected in series;

a total voltage measurement unit (11) that measures the total voltage of the plurality of cells (E1-Em); and

a control unit (15) that manages the internal impedance of each of the plurality of cells (E1-Em),

the control unit (15) detects a ripple of the total voltage measured by the total voltage measurement unit (11), multiplies the ratio of the internal impedance of each cell (En) of the plurality of cells (E1-Em) to the synthesized internal impedance by the detected ripple of the total voltage to estimate the ripple of each cell voltage, and determines whether the ripple of each cell voltage is within the range of the allowable voltage.

Thus, the ripple of each voltage of the plurality of cells (E1-Em) can be measured by a low-cost and small-scale circuit.

[ item 2]

A management device (10) is characterized by comprising:

a cell voltage measurement unit (12) that measures the voltage of each of a plurality of cells (E1-Em) connected in series;

a ripple detection section (15a) that detects ripples of cell voltages of a part of the cells (E1) among the plurality of cells (E1-Em); and

a control unit (15) that manages the internal impedance of each of the plurality of cells (E1-Em),

the control unit (15) estimates the ripple of each cell voltage based on the ripple of the voltage detected by the ripple detection unit (15a) and the internal impedances of the cells (E1-Em), and determines whether the ripple of each cell voltage is within the allowable voltage range.

Thus, the ripple of each voltage of the plurality of cells (E1-Em) can be measured by a low-cost and small-scale circuit.

[ item 3]

The management device (10) according to item 2, wherein the ripple detection section (15a) is provided to the control section (15).

Accordingly, the system size can be made small and large.

[ item 4]

The management device (10) according to any one of items 1 to 3, wherein the control unit (15) manages internal impedances of the respective cells in a frequency band corresponding to a frequency 2 times a commercial power supply frequency.

Thus, the ripple component superimposed on the slave system (5) can be measured with high accuracy.

[ item 5]

The management device (10) according to any one of items 1 to 4, further comprising:

a current measurement unit (14) that measures currents flowing in the plurality of cells (E1-Em); and

a temperature measuring unit (13) that measures the temperature of the plurality of cells (E1-Em),

the control unit (15) includes a table (15b) in which characteristic data Of the State Of Charge (SOHlang) and the State Of Charge (SOC) Of the unit (E1-Em) are described, wherein the characteristic data Of the unit (E1-Em) includes a value Of the State Of Charge (EN-US >),

the control unit (15) determines the internal impedance of each cell (En) by referring to the table (15b) based on the SOH, SOC, and temperature of each cell (En).

Thus, the internal impedance of each cell (En) can be estimated with high accuracy.

[ item 6]

The management device (10) according to any one of items 1 to 4, further comprising:

a current measuring unit (14) that measures currents flowing in the plurality of cells (E1-Em),

the control unit (15) estimates the internal impedance of each cell (En) based on the voltage change of each cell (En) before and after a predetermined current is supplied to the plurality of cells (E1-Em).

Thus, the internal impedance of each cell (En) can be estimated with high accuracy.

[ item 7]

An electrical storage system (1) is characterized by comprising:

a plurality of cells (E1-Em) connected in series; and

the management device (10) according to any one of items 1 to 6, wherein the plurality of cells (E1-Em) are managed.

Thus, it is possible to construct an electric storage system (1) capable of measuring the ripple of each voltage of the plurality of cells (E1-Em) with a low-cost and small-scale circuit.

Description of the symbols

The power storage system comprises a power storage system 1, an inverter 2, a motor 3, a charger 4, a system 5, a SW 11 st relay, a SW 22 nd relay, a management device 10, a total voltage measuring part 11, a unit voltage measuring part 12, a temperature measuring part 13, a current measuring part 14, a control part 15, a calculation part 15a, an internal impedance table 15b, a driving part 16, a power storage module 20, an E1-Em unit, an Rs shunt resistor, a T1 temperature sensor, a R1 1 st voltage dividing resistor, a R2 2 nd voltage dividing resistor and an 11a peak holding circuit.