KR20080104861A - Inverter logic for estimating state of health and apparatus for control thereof - Google Patents

Abstract

An inverter logic for estimating state of health and Apparatus for control thereof is provided to estimate the state of charging and lifetime of a battery accurately and improve the efficiency of the inverter. In an inverter logic for estimating state of health and apparatus, an information receiving unit(441) receives the inverter information while being connected to the battery and the inverter. A controller determines whether a specific cell is not identical with the voltage of the different cell or not, if so, it controls a cell control module to discharge or bypass the specific cell. The controller controls the output voltage and the frequency of the inverter by controlling a voltage frequency control module and estimates the lifetime of battery by increasing increases the number of charge and discharge if the accumulated capacity of the battery larger than a rated capacity of the battery or same.

Description

Inverter logic for estimating battery life and inverter circuit {Inverter logic for estimating state of health and Apparatus for control

1 is a structural diagram of a general battery management system.

2 is a block diagram of a standalone solar system to which a battery management system is applied.

3 is a block diagram of an inverter circuit for battery life estimation according to the present invention.

4 is a detailed block diagram of a control device of an inverter circuit for battery life estimation of FIG. 3.

5 is a flowchart illustrating a process of estimating battery remaining capacity (SOC) in the main controller of FIG. 4.

6 is a flowchart illustrating a process of estimating battery life (SOH) in the main controller of FIG. 4.

The present invention relates to a power supply device, and more particularly, to a control device of an inverter circuit for battery life estimation and an inverter circuit thereof.

The structure of a general BMS is shown in FIG.

In DC power or uninterruptible power supplies supplied from solar cells, the input voltage flows into the battery pack to charge the battery.

The current sensor senses the increased charging current and if it exceeds a certain level, it applies a signal to stop charging and discharges the battery when the solar power is not available or when the battery power is used during power failure. It begins.

On the other hand, while the charging or discharging operation is in progress, the voltage of the cell is read from both of the unit cells CELL 1 to CELL 8 of the battery module and applied to the cell balancing block. In the cell balancing block, cell balancing is performed by comparing the voltage level of each cell to exclude cells with the highest and lowest values and forcibly discharging or bypassing the voltage deviation of another cell based on one cell having an average voltage value. It will work. The main processor unit module (MPU MODULE) controls the cell balancing module according to the information on the charging current received through the current sensor and the A / D & D / A module (A / D & D / A MODULE).

On the other hand, by attaching a thermistor for sensing the temperature to the body of each cell of the battery module to sense the body temperature of the cell to sense the overheating or abnormal state of the cell to stop the operation of the system if necessary.

The SOC module estimates a state of charge (SOC) and estimates a state of health (SOH) from voltage, current, and SOC.

2 is a stand-alone type consisting of a battery 220 for storing a variable DC voltage generated from the solar cell 210, a battery management system 230 for managing the state of the battery, and an inverter 240 for converting direct current into alternating current (AC). A simple structure of the solar system is shown.

Meanwhile, the most important part of an uninterruptible power supply system (UPS) depends on how long a stable power supply is provided in case of a power failure. The source of this electricity is the battery. The battery is normally charged by the charger, and generates and supplies electricity through discharge from the battery in case of power failure or emergency. One UPS has multiple batteries connected in series or in parallel to provide longer electricity. However, even if only one of these batteries has a problem, it may not be possible to supply electricity or may cause an accident to be turned off and on for a very short time. A plurality of batteries have some deviations, each of which becomes larger and larger over time.

In case of applying BMS (Battery Management System) to UPS, it manages and maintains a plurality of batteries in the same state through individual management, that is, the best charging and discharging and no deviation between each battery. The side effect of increasing the service life of the can also be obtained. Therefore, the function of BMS in UPS is indispensable. In reality, however, very few products are equipped with BMS functionality on the UPS, and additional BMS circuits must be added.

In general, the number of charge / discharge cycles of the battery is counted to indicate the aging degree as a percentage against the number of charge-discharge cycles guaranteed by the manufacturer of the battery cell. However, in reality, the battery used in a mechanical device has a clear charge / discharge cycle of full charge and complete discharge. It is not terminated, and may be discharged in a partially charged state, or may be partially discharged and then recharged, and thus a counter of the exact number of charge / discharge cycles is impossible. As a result, there is a limit to accurately estimate the aging degree of the battery cell. In addition, conventionally, a separate SOC module is required to estimate battery remaining capacity, and since the remaining capacity is estimated without considering various states of the battery, its accuracy is low.

Therefore, the conventional power supply device has to have a battery management system separately, the efficiency of the inverter is lowered, the size and maintenance of the equipment is not easy to maintain, there is a problem that can not accurately predict the remaining capacity and life of the battery.

Therefore, the first technical problem to be achieved by the present invention is to provide a battery management system without the need for a separate battery management system if only the inverter circuit in the power supply, improve the efficiency of the inverter, it is easy to miniaturize and maintain the equipment, the battery The present invention provides a control device of an inverter circuit for battery life estimation that can accurately predict the remaining capacity and lifetime of a battery.

 The second technical problem to be achieved by the present invention is to provide an inverter circuit for estimating battery life to which the control device of the inverter circuit is applied.

In order to achieve the first technical problem, the present invention is connected to a battery and an inverter information receiving unit for receiving battery information and inverter information; A cell control module configured to adjust each cell voltage of the battery; A voltage frequency control module that adjusts the voltage and frequency of the inverter; And if it is determined from the battery information that the voltage of the specific cell is not equal to the voltage of another cell, the cell control module is controlled to forcibly discharge or bypass the specific cell for a predetermined time, and the voltage according to the inverter information. Control the frequency control module to adjust the output voltage and frequency of the inverter, and if the cumulative capacity accumulated by the battery using the battery information is greater than or equal to the rated capacity of the battery by increasing the number of charge and discharge current Provided is a control device of an inverter circuit for estimating battery life including a main controller for calculating the life of the battery.

In order to achieve the second technical problem, the present invention is an inverter for converting the DC voltage and current of the battery into an alternating current; An information receiver connected to the battery and the inverter to receive battery information and inverter information; A cell control module configured to adjust each cell voltage of the battery; A voltage frequency control module that adjusts the voltage and frequency of the inverter; And controlling the cell control module according to the battery information to forcibly discharge or bypass the specific cell for a predetermined time, and controlling the voltage frequency control module according to the inverter information to adjust the voltage and frequency of the inverter. And a main controller that calculates the life of the battery by increasing the number of charge / discharge cycles when the accumulated capacity of the battery using the battery information is greater than or equal to the rated capacity of the battery. Provide an inverter circuit.

The present invention relates to an inverter and a BMS of a solar power and an uninterruptible power supply. In the related art, an inverter and a battery management system (BMS) are respectively configured to serve as a inverter and a battery that converts direct current into alternating current and a battery. Although the functions of the management system were respectively handled, the circuit according to the present invention includes the functions of the inverter forward function and the battery management system (BMS).

According to the present invention, by providing a function of a battery management system (BMS) to an inverter which is essential for a solar system and an uninterruptible power supply system, it is possible to manage each cell without adding a separate battery management system.

In general, the basic specifications required for solar inverters are to convert DC power by photovoltaic power generation effectively into alternating current power to achieve high efficiency of the inverter and to facilitate the downsizing and maintenance of equipment.

The battery management system (BMS), which is installed separately from the photovoltaic system and the uninterruptible power supply system (UPS), has the temperature, voltage, and current sensed from each cell through the A / D conversion section, and the information processed into the SOC and SOH at the main control section is LAN. The transmitter is configured to be communicated to the user through a status display (eg, an LCD display).

3 is a block diagram of an inverter circuit according to the present invention.

The battery 310 stores the DC voltage, and converts the DC voltage into AC in the inverter circuit 300 and supplies the DC voltage to the load 390. In this case, the inverter 330 includes a resonant or bridge inverter for converting DC power into AC of commercial frequency.

The inverter circuit 300 removes harmonics from the square wave output of the input filter 320 for stabilizing the input power, the inverter 330 for outputting DC power as an alternating current, and the inverter 330, and outputs a good sine wave. The sine filter 350 and the protection function for protecting the inverter circuit 300 from abnormalities such as overvoltage, overcurrent, short circuit, disconnection, BMS function indicating SOC and SOH, and inverter output according to the variation of the load 390. It is composed of a control device 340 for controlling.

As the BMS and the inverter configured separately as above, the BMS function is embedded in the inverter function, and the cell control is possible by reinforcing the function of the main control circuit configured in the inverter without adding a separate battery management system (BMS).

4 is a detailed block diagram of the control device 340 of the inverter circuit for estimating the battery remaining capacity and the lifetime of FIG. 3.

The information receiver 441 is connected to the battery 310 and the inverter 330 to receive battery information and inverter information. In addition, the information receiver 441 receives the output information from the output terminal of the inverter circuit 300 to make the output delivered to the load 390 constant. Preferably, the battery information includes temperature, voltage and current measured from the battery, and the inverter information may include input / output voltage and current of the inverter.

The information receiver 441 may include a multiplexer, an A / D converter, a reference voltage supply device, or the like. The multiplexer is the information for judging and controlling in the main controller 442, and selectively receives the temperature, voltage, current of the battery or the voltage and current of the inverter, and transfers the analog signal to the digital signal to the A / D converter. do. The reference voltage supply device supplies a constant voltage to the A / D converter to have a reference value when the A / D converter converts an analog signal into a digital value.

The control unit 442 (Micro Control Unit; MCU) monitors the battery state information, that is, the temperature, voltage, current and the input / output voltage, current of the inverter in real time to determine and control the state of the battery and the inverter state of the battery 310 and Optimize the inverter 330.

For example, after reading the temperature, voltage, and current of the battery 310 from the information receiver 441 and comparing the cell voltages, the cell voltages are not constant, that is, the voltage of one cell is higher than the voltage of another cell. If measured, the main controller 442 causes the specific cell to be forcedly discharged for a predetermined time through the cell control module 443. On the contrary, if a specific cell voltage is measured to be lower than that of another cell, the main controller 442 adjusts the specific cell to be bypassed for a predetermined period of time through the cell control module 443 to match the other cell voltage.

In addition, the main controller 442 reads the output voltage and current of the inverter 330 from the information receiver 441, and then controls the voltage frequency control module 444 so that a constant voltage and current are always output.

If overvoltage or overcurrent and a circuit abnormality occur, the main controller 442 immediately operates the protection circuit 445 to protect the circuit by cutting off the current flowing in the circuit.

On the other hand, one of the important functions of the main controller 442 is to estimate the remaining capacity of the battery by processing the information of the temperature, voltage, and current of the battery read from the information receiver 441. The calculated information is transmitted to the status display window 460 via a LIN or a LAN transmitter, and the status display window 460 transmits this information to the user.

Preferably, the main controller 442 measures the voltage of the battery 310 as a primary value with respect to an initial value including a measurement time interval, a full voltage, a complete voltage, and a rated capacity of the battery 310. Measure the voltage secondly according to the measurement time interval of. In this case, the initial value may be included in the battery information received by the government receiver 441, or may be a method recorded in the main controller 442 itself.

At this time, if the voltage value of the secondary is equal to the voltage value of the primary, the main control unit 442 measures the current consumption and calculates the consumption by multiplying the current consumption by the measurement time interval, using the consumption and rated capacity The remaining capacity of the battery can be calculated. At this time, the main controller 442 measures the current consumption when the secondary voltage value is smaller than the primary voltage value, calculates the remaining voltage by subtracting the relaxation voltage from the primary voltage, and calculates the remaining voltage. The remaining time can be calculated by dividing the remaining voltage by the voltage difference between the secondary voltages, and the remaining capacity of the battery can be calculated by multiplying the remaining time with the current consumption. At this time, the main controller 442 may calculate the remaining capacity of the battery by dividing the secondary voltage value by the full voltage when the secondary voltage value is larger than the primary voltage value.

Another important function of the main controller 442 is to estimate the remaining life of the battery by processing the temperature, voltage, and current information of the battery read from the information receiver 441. The calculated information is also transmitted to the status display window 460 via a LIN or a LAN transmitter, and the status display window 460 transmits this information to the user. In this case, in order to estimate the battery life more accurately, it is not necessary to simply consider the number of charge and discharge cycles, but also consider the battery internal impedance and the age or retention of the battery.

Preferably, the main control unit 442 is a battery measurement time interval and the full voltage value, the complete voltage value, the rated capacity of the battery, the number of guaranteed charge and discharge of the battery and the current charge and discharge, the battery manufacturing date and initial battery internal impedance, etc. For an initial value including a, the voltage of the battery 310 is measured first, and the voltage is measured secondly according to the measurement time interval of the initial value. In this case, the initial value may be included in the battery information received by the information receiver 441 or may be a method recorded in the main controller 442 itself.

At this time, the main controller 442 calculates the consumption capacity by multiplying the consumed current by the measurement time interval when the primary voltage value is greater than the secondary voltage value, and when the cumulative capacity that accumulated the consumed capacity is greater than or equal to the rated capacity. You can increase the number of charge / discharge cycles by one. In this case, the current charge / discharge count is the life of the battery compared to the guaranteed charge-discharge count.

Preferably, the main controller 442 divides the difference between the primary voltage value and the secondary voltage value by the current consumption of the battery when the difference between the primary voltage value and the secondary voltage value is greater than zero. The impedance may be calculated, and the battery life may be corrected according to the calculated internal impedance.

Preferably, the main controller 442 may be configured to calculate the age of use (preservation) of the battery by comparing the life of the battery with the manufacturing date of the battery so that 5% of the total life is reduced after one year. The display window 460 may be configured to display the life of the battery and the age of use (preservation) of the battery.

The electrostatic source supply device (not shown) supplies operating power for the circuits of the control device 440 to operate.

5 is a flowchart of a process of estimating battery remaining capacity (SOC) in the main controller 442 of FIG. 4.

First, when the SOC estimation operation of the battery is started, an initial value is first set. In this case, the initial value includes the measurement time interval, the full voltage value, the complete voltage value, the rated capacity of the battery, the guaranteed charge and discharge times of the battery and the current charge and discharge times, the battery manufacturing date and the initial battery internal impedance. The initial value can be set only once.

Next, input an initial value and measure the primary voltage (OCV: Open Circuit Voltage) (step 510).

When the primary voltage is measured, the secondary voltage by the measurement time interval given to the initial value is measured (step 520).

Next, the second voltage measurement value is compared with the first voltage measurement value (step 530).

At this time, if the measured secondary voltage is not different from the primary voltage value, there is almost no current consumption, but there is a minute current consumption and the current consumption is measured (step 531).

Next, the measured consumption current is multiplied by the initial measurement time interval given to give a consumption capacity (step 532).

Next, the remaining capacity is calculated by subtracting the consumed capacity from the initial stored battery capacity (step 533).

Once the remaining capacity is found, the remaining capacity is divided by the rated capacity given by the initial value and multiplied by 100 to inform the user of the current capacity (step 534).

On the other hand, if the secondary voltage measurement value is different from the primary voltage measurement value by measuring the initial primary voltage measurement value and the secondary voltage measurement value, the difference between the primary voltage value and the secondary voltage value is measured. When the voltage value is subtracted, there may be a case where the value is larger than 0 and smaller than 0 (step 540).

If the voltage value of the primary is subtracted from the voltage value of the secondary, the value less than 0 is the case that the voltage of the secondary is greater than the voltage of the primary. At this time, it can be seen that the battery is in a charged state. Since there is no current consumption during charging, the current capacity is calculated by simply dividing the secondary voltage reading by the full voltage value and multiplying by 100 (step 550).

On the other hand, subtracting the secondary voltage measurement from the primary voltage measurement is greater than zero, indicating that there is current consumption due to system operation.

In this case, the current consumption is measured (step 541), and the remaining voltage value is calculated by subtracting the relaxation voltage value from the first measured voltage value (step 542).

Next, the remaining voltage value is divided by the voltage difference obtained by subtracting the second voltage measurement value from the first voltage measurement value, and the remaining time is calculated by multiplying the initially input time interval (step 543).

Finally, the remaining capacity is multiplied by the current consumption to calculate the remaining capacity (step 544), and the remaining capacity is divided by the rated capacity and multiplied by 100 again to inform the user of the current capacity (step 545).

6 is a flowchart illustrating a process of estimating battery life (SOH) in the main controller 442 of FIG. 4.

First, when the SOH estimation operation of the battery is started, an initial value is first set. In this case, the initial value includes the measurement time interval, the full voltage value, the complete voltage value, the rated capacity of the battery, the number of guaranteed charge and discharge of the battery and the current number of charge and discharge, the battery manufacturing date and initial battery internal impedance. The initial value can be set only once.

Next, when the initial initial value is set, the primary voltage, that is, the OCV (Open Circuit Voltage) is measured (step 610).

When the primary voltage is measured, the secondary voltage, that is, the current voltage, is measured by the measurement time interval given to the initial value (step 620).

When the primary and secondary voltages are measured, the secondary voltage measurement value is compared with the primary voltage measurement value (step 630). The comparison method may be performed by subtracting the second voltage measurement value from the first voltage measurement value to compare whether the value is greater than zero.

At this time, if the value obtained by subtracting the secondary voltage measurement value from the primary voltage measurement value is equal to or less than 0, the state of charging or no current consumption is returned to the secondary voltage measurement state. Compared to the value, it has a cycle until it is discharged.

At this time, if the value obtained by subtracting the secondary voltage measurement value from the primary voltage measurement value is greater than 0, it can be seen that the discharge state. In this case, the following process (process 631-533) is performed.

If the first voltage measurement minus the second voltage measurement is greater than zero, i.e., in the discharged state, the sum of the discharge current time (t) and the current flowing during the corresponding discharge current time (t), i.e. In operation 631, the current consumption is calculated.

Next, the discharge capacity, that is, the consumption capacity is calculated by multiplying the consumed current by the corresponding discharge current time t (step 632).

Next, the accumulated capacity is obtained by multiplying the consumed capacity by the corresponding discharge current time t (step 633). This process (step 633) is a process of detecting a section that is in a discharged state as time passes, continuously obtaining a discharge capacity for the corresponding section, and then accumulating the discharge capacities of the corresponding section.

When the cumulative capacity is calculated, it is checked whether the cumulative capacity is equal to or greater than the full charge capacity (FCC) of the battery initial setting value (step 640). At this time, if the cumulative capacity is less than the rated capacity to return to the secondary voltage measurement step.

On the other hand, if the cumulative capacity is greater than the rated capacity, it is considered that one charge / discharge cycle is completed by increasing the number of charge / discharge cycles of the battery (step 641).

Next, the internal impedance is calculated by dividing the difference between the primary voltage and the secondary voltage in the discharge state by the consumption current (discharge current) in the discharge state (step 642).

Once the internal impedance is obtained, the degree of aging, or SOH, is calculated by comparing the current number of charge / discharge cycles of the battery with the battery manufacturer's guaranteed charge / discharge lifetime (step 643). The preservation (use) age is calculated in such a way that 5% of the total life is reduced after 1 year compared to the manufacturing date of the process (step 644).

5 and 6 may be embedded in the main controller 442 of FIG. 4 in the form of firmware, and may be performed by an operation processor embedded in the main controller 442.

The invention can be implemented via software. When implemented in software, the constituent means of the present invention are code segments that perform the necessary work. The program or code segments may be stored on a processor readable medium or transmitted by a computer data signal coupled with a carrier on a transmission medium or network.

Computer-readable recording media include all kinds of recording devices that store data that can be read by a computer system. Examples of computer-readable recording devices include ROM, RAM, CD-ROM, DVD-ROM, DVD-RAM, magnetic tape, floppy disks, hard disks, optical data storage devices, and the like. The computer readable recording medium can also be distributed over network coupled computer devices so that the computer readable code is stored and executed in a distributed fashion.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary and will be understood by those skilled in the art that various modifications and embodiments may be made therefrom. However, such modifications should be considered to be within the technical protection scope of the present invention. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, according to the present invention, by integrating the battery management system in the control terminal of the inverter circuit, it is not necessary to provide a separate battery management system provided that only the inverter circuit in the power supply device, and improve the efficiency of the inverter, Miniaturization and maintenance of the facility is easy, and the remaining capacity and life of the battery can be accurately predicted.

Claims (13)

An information receiver connected to the battery and the inverter to receive battery information and inverter information; A cell control module configured to adjust each cell voltage of the battery; A voltage frequency control module that adjusts the voltage and frequency of the inverter; And If it is determined from the battery information that the voltage of a specific cell is not the same as the voltage of another cell, the cell control module is controlled to forcibly discharge or bypass the specific cell for a predetermined time, and the voltage frequency according to the inverter information. Control the output module and the frequency of the inverter by controlling a control module, and if the cumulative capacity accumulated by the battery capacity using the battery information is greater than or equal to the rated capacity of the battery by increasing the number of charge and discharge current Control device of the inverter circuit for estimating the battery life including a main controller for calculating the battery life. The method of claim 1, The main fisherman For the initial value including the measurement time interval and full voltage value of the battery, the complete voltage value, rated capacity, the number of guaranteed charge and discharge, the current charge and discharge, the battery manufacturing date and initial battery internal impedance through the information receiver, The primary voltage of the battery is measured and the secondary voltage is measured according to the measurement time interval. When the primary voltage value is larger than the secondary voltage value, the consumption current is multiplied by the measurement time interval. And calculating a lifespan of the battery by increasing the number of charge / discharge cycles when the cumulative capacity that accumulates the consumption capacity is greater than or equal to the rated capacity. The method of claim 2, The main fisherman When the difference between the primary voltage value and the secondary voltage value is greater than zero, the difference between the primary voltage value and the secondary voltage value is divided by the current consumption to calculate an internal impedance, and the calculated The control device of the inverter circuit for battery life estimation, characterized in that for correcting the life of the battery in accordance with the internal impedance. The method of claim 2, The main fisherman Comparing the life of the battery with the date of manufacture of the battery so that 5% of the total life is reduced by one year to calculate the service life of the battery, characterized in that for calculating the battery life of the inverter circuit. The method of claim 1, The main fisherman And calculating the remaining capacity of the battery using the battery information. The method of claim 5, wherein The main fisherman For the initial value including the measurement time interval of the battery, the full voltage, the complete voltage, and the rated capacity of the battery, the voltage of the battery is measured first and the voltage is measured secondly according to the measurement time interval of the initial value. If the secondary voltage value is the same as the primary voltage value, the current consumption is measured, and the power consumption is calculated by multiplying the current consumption by the measurement time interval, and using the power consumption and the rated capacity of the battery A control device of an inverter circuit for battery life estimation, characterized in that the remaining capacity is calculated. The method of claim 6, The main fisherman When the secondary voltage value is smaller than the primary voltage value, the current consumption is measured, the remaining voltage is calculated by subtracting the relaxation voltage from the primary voltage, and the residual voltage and the secondary voltage are calculated. And calculating the remaining time by dividing the remaining voltage by the voltage difference between the voltages and calculating the remaining capacity of the battery by multiplying the remaining time with the consumed current. The method of claim 6, The main fisherman And when the secondary voltage value is greater than the primary voltage value, dividing the secondary voltage value by the full voltage to calculate the remaining capacity of the battery. . The method of claim 1, And the battery information includes temperature, voltage, and current measured from the battery, and the inverter information includes an input voltage and a current of the inverter. An inverter for converting a DC voltage and a current of the battery into alternating current; An information receiver connected to the battery and the inverter to receive battery information and inverter information; A cell control module configured to adjust each cell voltage of the battery; A voltage frequency control module that adjusts the voltage and frequency of the inverter; And Control the cell control module according to the battery information to force discharge or bypass the specific cell for a predetermined time, and control the voltage frequency control module according to the inverter information to adjust the voltage and frequency of the inverter; An inverter for estimating battery life including a main control unit that calculates the life of the battery by increasing the number of charge / discharge cycles when the accumulated capacity of the battery using the battery information is greater than or equal to the rated capacity of the battery. Circuit. The method of claim 10, The main fisherman And calculating the remaining capacity of the battery by using the battery information. The method of claim 10, And a status display window for visually displaying the calculated lifespan. The method of claim 10, An input filter connected between the battery and the inverter to supply a stable direct current to the inverter; And And a sine wave filter connected to an output terminal of the inverter to remove harmonics from a square wave output of the inverter.

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