KR101413957B1 - Device for battery management - Google Patents

Abstract

The present invention relates to a battery management apparatus, and more particularly, a battery management apparatus according to the present invention includes a plurality of battery cells connected in series; A voltage detector for detecting a voltage of each battery cell and comparing the detected voltage with a reference voltage; And a blocking signal generator for controlling the battery cells to be disconnected from the charging and discharging circuit when the voltage of the deteriorated cell having the smallest capacitance among the battery cells is out of the range of the reference voltage.
According to the present invention, by setting the overcharge and overdischarge reference voltages based on the deteriorated cells, the life of the deteriorated cells can be maximized and the performance of the entire battery pack can be maximally maintained.

Description

Device for battery management < RTI ID = 0.0 >

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a battery management device, and more particularly, to a circuit for protecting a secondary battery from overcharging, overdischarging, overvoltage, overcurrent, and the like of a plurality of secondary batteries.

Battery technology is divided into production technology and control technology. Control technology is divided into PCM (Protection circuit module), SM (Smart module) and BMS (Battery management system) depending on battery capacity and application.

Generally, in order to manufacture a large capacity battery, a plurality of battery cells are often connected in series or in parallel. In this case, as the charge / discharge is repeated while using the battery, the voltage difference between the battery cells becomes larger and the unbalance tends to occur. In this case, the life of the entire battery is shortened by some of the deteriorated battery cells, and even the risk of fire or explosion increases. The battery management device monitors the current, voltage, temperature, and remaining capacity of each battery cell and performs an alarm or power off function when an abnormal condition is detected.

As an example of such a technique, Korean Patent Laid-Open No. 10-2006-0060830 entitled "Charge / discharge control device having a battery cell balancing function and method for setting optimal battery module use conditions using the same," have.

1, a control signal is applied to the charge / discharge control means 20 so that the battery module 3 is charged / discharged in an optimal setting state, and the sensing means 40 and the temperature Discharging is terminated in an optimum state through the signal value transmitted through the measuring means 60 and a control signal is applied to the balancing means 30 so as to maintain the voltage of each battery cell at the same value A charge / discharge terminal is formed so as to be supplied to the battery module by holding a predetermined amount of current and voltage with respect to the power supplied from the power source unit 70 under the control of the control means (0) Charging and discharging control means (20) for controlling the discharge control transistors (Q1, Q2), and when the charging and discharging end condition is reached while monitoring the current and voltage values flowing from the sensing resistor (RS) The discharge control means A sensing resistor (RS) for outputting a voltage generated in the load to the sensing unit when the battery module is charged / discharged through the charge / discharge control unit, A temperature measuring means 60 for detecting the temperature of each battery cell and outputting the detected temperature to the control means 60, And balancing means (30) for balancing the voltage of each battery cell to maintain the same voltage through the control voltage applied by the means.

Specifically, as shown in FIG. 2, the background art 1 balances each battery cell 4 through the balancing means 30 when the cells 4 are connected in series. The balancing means 30 includes comparators 32, 33, 34, 35 and 36 for comparing the voltages of the respective battery cells 4 with the voltages Vc1, Vc2, Vc3 and Vc4 transmitted from the control means . That is, in the background art 1, the voltage of each battery cell is compared with the reference voltage. As a result, it can be seen that the size of the entire circuit is increased by providing a circuit for comparing voltages such as a comparator for each battery cell.

That is, it is required that the battery management apparatus accurately measures the voltage of each battery cell before checking the performance of each battery cell or managing the power of the entire battery prior to charging operation. However, in a case where a plurality of battery cells are commonly connected to the ground and a comparison is made with a reference voltage for measuring the voltage of the battery cell, it is not easy to accurately calculate the voltage value of each battery cell as the number of cells increases . Also, when charging / discharging is stopped to check each battery cell during charging or discharging, accurate voltage measurement can not be performed. In addition, configuring a circuit for measuring the voltage of each battery cell to measure the voltage of each battery cell may increase the complexity of the device itself, thereby causing an error in measuring the voltage, thereby lowering the accuracy.

On the other hand, the performance of the battery pack can be determined by a deteriorated cell having the smallest electric capacity among a plurality of battery cells constituting the battery pack. Deteriorated cells connected in parallel with other battery cells may cause a decrease in the battery capacity by increasing the amount of natural discharge in the battery pack and may cause a short circuit or an open circuit in case of severe deterioration, It may be the cause. On the other hand, in the case of a battery cell connected in series with other battery cells, when the discharging reaches the overdischarge reference voltage first and the other battery reaches the overdischarge reference voltage, the deteriorated cell falls below the overdischarge reference voltage . Likewise, at the time of charging, the deteriorated cell first reaches the overcharge reference voltage due to the low capacitance. When the other battery cells reach the overcharge reference voltage, the deteriorated cell already exceeds the overcharge reference voltage. If such overcharge and overdischarge persist, the life of the deteriorated cell may be further shortened and the performance of the entire battery pack may be seriously degraded.

The present invention provides an apparatus for controlling charging and discharging so as to maximize the service life of the battery pack itself.

The present invention also provides an apparatus for precisely calculating the voltage value of each battery cell without having a separate ground electrode when a plurality of battery cells are charged in series for precise charge / discharge control.

A battery management apparatus according to the present invention includes: a plurality of battery cells connected in series; A voltage detector for detecting a voltage of each battery cell and comparing the detected voltage with a reference voltage; And a blocking signal generator for controlling the battery cells to be disconnected from the charging and discharging circuit when the voltage of the deteriorated cell having the smallest capacitance among the battery cells is out of the range of the reference voltage.

Also, the blocking signal generator may include a blocking signal generator for controlling the battery cells to be disconnected from the charge / discharge circuit when the voltage of any one of the battery cells detected by the voltage detector is higher than the overcharge reference voltage or lower than the overdischarge reference voltage .

Further, the voltage detector may include a first node including a first battery cell to a kth battery cell (k is an arbitrary natural number equal to or smaller than n) of the battery cells with respect to a common ground, a switching unit for switching a voltage output from an output pair formed by a second node including a (k-1) battery cell; And a comparator for comparing a voltage input from the first node with a voltage input from the second node and a sum of the reference voltage to compare the voltage of the k < th > battery cell with the reference voltage, have.

Further, the switching unit may include a cell switch having a plurality of switching modes according to the k value; And a ring counter for controlling the cell switch to sequentially switch between the plurality of switching modes.

Further, the comparator may include an OP amp voltage comparator.

Further, the comparator compares the voltages of the output pairs in each switching mode sequentially switched, and may output an abnormal signal when the voltage input to the inverting input terminal is greater than the voltage input to the non-inverting input terminal.

The comparator may further include a first comparator having a first non-inverting input terminal to which the first node is connected and a first non-inverting input terminal to which the second node is connected, A first voltage source having a magnitude corresponding to the magnitude of the overcharge reference voltage and having a cathode connected to the second node side may be interposed between the nodes.

The comparator may further include a second comparator having a first non-inverting input terminal connected to the first node and a second inverting input terminal connected to the second node, A second voltage source having a magnitude corresponding to the magnitude of the over-discharge reference voltage and having a cathode connected to the second node side may be interposed between the nodes.

The comparator may further include a first inverting input terminal connected to the first node and a second inverting input terminal connected to the second node in a state where a first voltage source having a voltage magnitude corresponding to the magnitude of the overcharge reference voltage, A first comparator having a first non-inverting input terminal to which a node is connected; And a second non-inverting input terminal connected to the first node and a second voltage source having a voltage magnitude corresponding to a magnitude of the over-discharge reference voltage to which the negative electrode is connected to the second node side, And a second comparator having a second inverting input terminal to which the first inverting input terminal is connected.

And a power switch for opening / closing an external charge / discharge circuit and an electrical connection of the battery cells.

Furthermore, the blocking signal generator may output a signal for controlling the power switch to be opened when any one of the first comparator and the second comparator outputs an abnormal signal.

Furthermore, the blocking signal generator may include any one of a latch, a flip-flop, and a sequential logic circuit.

And a current controller for sensing an amount of current supplied to the battery cells to shut off the power switch when an overcurrent flows.

A temperature sensing unit for measuring a temperature of each of the battery cells; And a temperature control unit for shutting off the power switch when the temperature measured by the temperature sensing unit is equal to or higher than a reference temperature.

According to the present invention, by setting the overcharge and overdischarge reference voltages based on the deteriorated cells, the life of the deteriorated cells can be maximized and the performance of the entire battery pack can be maximally maintained.

According to the present invention, the voltage of each battery cell can be precisely measured without providing a separate ground for measuring the voltage of the battery cell, thereby preventing a situation in which stability of the battery cell, such as overvoltage and overcharging, It is possible to use.

1 is a block diagram showing an internal configuration of a conventional battery charge / discharge control device.
2 is a block diagram showing an internal configuration of a conventional battery cell balancing means.
3 is a block diagram illustrating a battery management apparatus according to an embodiment of the present invention.
4 is a circuit diagram schematically showing a battery management apparatus including a voltage control unit according to an embodiment.
5 is a circuit diagram showing the principle of battery voltage detection according to the present invention.
6A is a circuit diagram showing a switching unit according to an embodiment.
6B to 6E are circuit diagrams showing a sequential operation of the switching unit according to the embodiment.
7 is a circuit diagram showing a state of a comparison unit according to an embodiment.
8 is a circuit diagram showing a state of a blocking signal generator according to an embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the absence of special definitions or references, the terms used in this description are based on the conditions indicated in the drawings. The same reference numerals denote the same members throughout the embodiments. For the sake of convenience, the thicknesses and dimensions of the structures shown in the drawings may be exaggerated, and they do not mean that the dimensions and the proportions of the structures should be actually set.

A battery management apparatus according to the present invention will be described with reference to FIG. 3 is a block diagram illustrating a battery management apparatus according to an embodiment of the present invention. 3, the battery management apparatus according to the present embodiment is a device for safely managing charge and discharge operations of the battery cell 300, and includes a power supply unit 100, a power switch 200, a voltage control unit 400, A current control unit 500, and a temperature control unit 600.

The battery cells 300 in this embodiment are connected in series. The power supply unit 100 supplies the charging power to the battery cells 300. The power switch 200 functions to open or close the power supplied to the battery cells 300 from the power supply unit 100 to perform charging or discharging. The power switch 200 may be a relay, an FET, or various switches.

The current controller 500 senses the amount of current supplied to the battery cells 300 by measuring the current flowing through the sensing resistor Rs. If it is determined that the measured current value is equal to or higher than the reference value, it is determined that the measured current value is an overcurrent, and a signal for shutting off power transmitted to the battery cell 300 is transmitted to the power switch 200.

The temperature control unit 600 measures the temperature of each battery cell 300 by attaching a temperature sensing unit (not shown) such as a thermistor or a PTC device to each of the battery cells 300. When the temperature measured by the temperature sensing unit (not shown) is equal to or higher than the reference temperature, the temperature controller 600 determines that the battery is not in the normal charge / discharge state and transmits a signal for shutting off power to the battery cell 300 200).

Hereinafter, for convenience of explanation, the voltage detector includes a cell switch 410, a ring counter 420, and a comparator 430 that are related to the detection of a voltage in each component included in the voltage controller 400, Particularly, the cell switch 410 and the ring counter 420 related to the technique of opening and closing each node to measure the voltage of the battery cell 300 are called a switching part, And a blocking signal generator for controlling the connection and disconnection of the signal.

Hereinafter, components for measuring a voltage around a voltage detecting unit will be described with reference to FIGS. 4 to 7. FIG. FIG. 4 is a circuit diagram schematically showing a battery management apparatus according to an embodiment, and FIG. 5 is a circuit diagram showing a principle of battery voltage detection according to the present invention. 6A is a circuit diagram illustrating a switching unit according to an embodiment of the present invention, and FIGS. 6B through 6E are circuit diagrams illustrating a sequential operation of the switching unit according to an exemplary embodiment. 7 is a circuit diagram showing a state of a comparison unit according to an embodiment.

First, the voltage detector will be described. As described above, the voltage detector refers to the cell switch 410, the ring counter 420, and the comparator 430, which are components involved in measuring the voltage of the battery cells 300. The battery cells 300 are referred to as a first battery cell V1, a second battery cell V2, a third battery cell V3 and a fourth battery cell V4 in this order connected to the ground GND side. In the embodiment shown in FIG. 4, a total of four battery cells are provided, but the present invention is not limited thereto. The same effect can be obtained if the number of related components increases in the same manner as the number of battery cells increases.

Before describing each constituent part of the voltage detection part, the principle of detecting the battery voltage according to the present invention will be described with reference to Fig. 5, the sum of the voltages of the second to fourth battery cells and the reference voltage Vref, i.e., V2 + V3 + V4 + Vref, is input to the non-inverting (+) input side of the comparator Cp And the sum of the voltages of the first to fourth battery cells, i.e., V1 + V2 + V3 + V4, is inputted to the inverting (-) input side of the comparator Cp. The comparison of the values of the two inputs of the comparator Cp results in the comparison of the voltage V1 of the first battery cell with the reference voltage Vref. The principle of comparing the voltages of the remaining second to fourth battery cells with the reference voltage is also the same. Each of the components described below uses the principle of measuring the battery cell.

The cell switch 410 is connected to node 1 and node 2 to measure the voltages of the respective battery cells V1, V2, V3 and V4 as shown in FIG. 6A. , V2, V3, and V4. For example, in the first switching mode, the switch 11 and the switch 12 can be closed as shown in FIG. 6B. In this case, the voltage of V1 + V2 + V3 + V4 is applied to node 2, and the voltage of V2 + V3 + V4 is applied to node 1. Next, in the second switching mode, the switch 21 and the switch 22 can be closed as shown in FIG. 6C. In this case, the voltage of V2 + V3 + V4 is applied to node 2, and the voltage of V3 + V4 is applied to node 1. Next, in the third switching mode, the switch 31 and the switch 32 can be closed as shown in FIG. 6D. In this case, the voltage of V3 + V4 is applied to node 2 (node 2), and the voltage of V4 is applied to node 1. Next, in the fourth switching mode, the switch 41 and the switch 42 can be closed as shown in FIG. 6E. In this case, a voltage of V4 is applied to node 2 (node 2), and a ground voltage is applied to node 1. (V1 + V2 + V3 + V4) and (Vref + V2 + V4) are applied to node 2 and node 1, respectively, when the reference voltage is added to node 1 in each switching mode. V3 + V4 and V2 + V3 + V4 and Vref + V3 + V4 and V3 + V4 and Vref + V4 and V4 and Vref, respectively.

The ring counter 420 generally refers to a circuit in which N coefficient elements are connected in an annular form, only one of them is in an operating state, and the operation state is shifted to a neighboring element every time one count pulse is applied. In this embodiment, the ring counter 420 performs a function of sequentially controlling the four switching states of the cell switch 410 described above. That is, the ring counter 420 outputs a signal (V1 + V2 + V3 + V4), (Vref + V2 + V3 + V4) (Vref + V4), and (V4) and (Vref) to the both input sides of the comparator 430, respectively.

The comparator 430 compares a predetermined reference voltage with a voltage measured from the battery cells 300 and determines whether or not the reference voltage is equal to or higher than a reference voltage. A dedicated comparator may be used as the comparator 430, but in the present embodiment, the OP AMP is used as shown in FIG. There are no restrictions on the types of comparators. Here, the reference voltage is a voltage value that can be variably changed according to the specification of each battery cell 300, and an allowable voltage value of each battery cell 300 is input in advance, that is, the reference voltage value is added to the node 1 described above By setting the circuit in advance.

The comparator in this embodiment has a first comparator Cp1 for comparing with the overcharge reference voltage and a second comparator Cp2 for comparing the overdischarge reference voltage. As described above, in the specific switching mode, the node 2 is switched to receive the voltage including the first to k-th battery cells, and a voltage including the first to (k-1) Lt; / RTI > The voltage including the first to (k-1) th battery cells and the overcharge reference voltage VH_ref are input to the non-inverting input terminal (+) of the first comparator Cp1, A voltage including the first through k-th battery cells is input to the inverting input terminal (-). Likewise, the voltage including the first through the k-th battery cells is input to the non-inverting input terminal (+) of the second comparator (Cp2) and the inverting input terminal (-) of the second comparator the voltage including the (k-1) -th battery cell and the overdischarge reference voltage VL_ref are input in a sum. Each comparator Cp1 and Cp2 outputs a signal (meaning a signal indicating an abnormality) to the output terminal out when the voltage inputted to the inverting input terminal (-) is larger than the voltage inputted to the non-inverting input terminal (+) do.

Meanwhile, as shown in FIG. 5, the comparator Cp may use a common ground with the switching unit including the battery cell. Generally, in order to accurately measure the voltage of the battery cell, the negative pole side of the battery cell must be connected to a ground separate from the ground to which the battery cells are connected, so that a risk of a sudden discharge or an overcurrent can be prevented. However, in the present invention, since the negative side node of the battery cell does not need to be connected to the ground electrode in order to measure the voltage of the specific battery cell, it is free from the configuration of the BMS.

V3 + V4, (V2 + V3 + V4), (V3 + V4), and (V3 + V4) by controlling the cell switch 410, ), (V4) and (V4) and (ground voltage) are respectively applied to node 2 and node 1, node 1 is supplied with overcharge reference voltage VH_ref and overdischarge reference voltage VL_ref, (V1 + V2 + V3 + V4), (Vref + V2 + V3 + V4) and (V2 + V3 + V4) and (Vref + V3 + V4) are input to the inputs of the comparators Cp1 and Cp2, , (V3 + V4), (Vref + V4), (V4) and (Vref) are sequentially inputted.

The blocking signal generators 440 and 450 will be described with reference to FIGS. 4 and 8. FIG. 8 is a circuit diagram showing a state of a blocking signal generator according to an embodiment. The blocking signal generators 440 and 450 transmit a signal to the power switch 200 to block the power supply according to the comparison result of the comparator 430. That is, the blocking signal generators 440 and 450 control the battery cells to be disconnected from the charging / discharging circuit when the voltage of the deteriorated cell having the smallest capacitance among the battery cells is out of the range of the reference voltage. Since the deteriorated cell is reduced in electric capacity, when charging or discharging at the same power, the battery cell reaches the overcharge reference voltage first or the overdischarge reference voltage as compared with other battery cells. Accordingly, if any one of the plurality of battery cells in the charge / discharge process reaches a pre-discharge reference voltage or an overcharge reference voltage, there is a high possibility that the corresponding cell is a deteriorated cell.

In addition, the blocking signal generators 440 and 450 transmit a signal to the power switch 200 to cut off the power supply according to the signal of the current controller 500. [ The blocking signal generators 440 and 450 in the present embodiment include an encoder 440 and a latch 450. The encoder 440 converts the analog signal transmitted from the comparator 430 or the current controller 500 into a digital format suitable for the logic circuit and transmits the analog signal. The latch 450 outputs a signal to interrupt power supplied to the power switch 200 in accordance with a signal transmitted from the encoder 440 as a kind of digital logic circuit. An example of such a latch 450 is shown in Fig. First, if one of the voltages exceeding the reference voltage range is detected from the comparators (Cp1, Cp2) for comparing the overcharge reference voltage and the overdischarge reference voltage, a signal of 1 is outputted through the OR gate. The latch 450 can cut off the power switch 200 by disconnecting the signal toward the power switch 200 when a signal of 1 is input. In this embodiment, the power switch 200 is taken as an example, but it may be a switch for disconnecting the battery cell from an external device to which power is supplied to stop the discharge. That is, the power switch 200 in this embodiment may be replaced or added with a switch for disconnecting an electrical connection with an external circuit for discharging as well as a power switch for charging. In addition, the above-described latches 450 can be replaced with various types of latches or flip-flops, or various sequential logic circuit devices including them, so long as they can achieve the same function or effect.

On the other hand, the current controller 500 measures the current supplied to the battery cells 300 as described above, and determines whether or not the battery cell 300 is in an overcurrent state.

The voltage detection process will be described below. When charging starts, each cell is checked. In this case, as described above, the mode is switched to the first switching mode to detect the voltage V1 (S10), and the detected voltage V1 is compared with the reference voltage. As a result of comparison, if the detected voltage exceeds or exceeds the overcharge reference voltage, a signal for supplying power is supplied to prevent overcharge as described above. Likewise, when the detected voltage is lower than or equal to the over discharge reference voltage, a signal for shutting off the supply power is sent to prevent over discharge. Next, the mode is switched to the second switching mode to detect the voltage V2. In this way, the voltages V3 and V4 are compared with the reference voltage while sequentially switching between the third switching mode and the fourth switching mode.

On the other hand, the adding voltage can be applied by separating the ground using a photocoupler or the like.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Can be implemented.

100: Power supply unit 200: Power switch
300: battery cells 400: voltage control unit
410: Cell switch 420: Ring counter
430: comparator 440: encoder
450: latch 500: current control unit
600:

Claims (14)

A plurality of battery cells connected in series;
A voltage detector for detecting a voltage of each battery cell and comparing the detected voltage to at least one reference voltage of an overcharge reference voltage and an overdischarge reference voltage; And
When the voltage of the battery cell that reaches the reference voltage first among the voltages of the battery cells in the charging and discharging process is larger than the overcharge reference voltage or lower than the over discharge reference voltage, A blocking signal generator for controlling the blocking signal generator,
The voltage detector may include:
(K-1) battery cells from the first battery cell to the (k-1) th battery cell from the first battery cell to the kth battery cell (k is an arbitrary natural number) A switching unit for switching a voltage to be output from an output pair formed by the second node; And
And a comparator for comparing a voltage input from the first node with a voltage input from the second node and a sum of the reference voltage to compare the voltage of the k < th > battery cell with the reference voltage, Device. delete delete The method according to claim 1,
The switching unit includes:
A cell switch having a plurality of switching modes according to the k value; And
And a ring counter for controlling the cell switch to sequentially switch between the plurality of switching modes. 5. The method of claim 4,
Wherein the comparator includes an OP amp voltage comparator. 6. The method of claim 5,
Wherein the comparator compares the voltages of the output pair in each switching mode sequentially switched and outputs an abnormal signal when the voltage input to the inverting input terminal is greater than the voltage input to the noninverting input terminal. The method according to claim 6,
Wherein,
And a first comparator having the first node connected to the first inverting input terminal and the second node connected to the first non-inverting input terminal,
Wherein a first voltage source having a magnitude corresponding to the magnitude of the overcharge reference voltage and having a cathode connected to the second node side is interposed between the first non-inverting input terminal and the second node. The method according to claim 6,
Wherein,
And a second comparator in which the first node is connected to the second non-inverting input terminal and the second node is connected to the second inverting input terminal,
And a second voltage source having a magnitude corresponding to the magnitude of the over-discharge reference voltage and having a cathode connected to the second node side is interposed between the second inverting input terminal and the second node. The method according to claim 6,
Wherein,
A second node connected to the first node with a first voltage source of a voltage magnitude corresponding to the magnitude of the overcharge reference voltage to which the negative electrode is connected to the second node side, A first comparator having a first non-inverting input terminal; And
A second non-inverting input terminal connected to the first node and a second voltage source having a voltage magnitude corresponding to the magnitude of the over-discharge reference voltage to which the negative electrode is connected to the second node side, And a second comparator having a second inverting input terminal connected thereto. 10. The method of claim 9,
And a power switch for opening / closing an external charge / discharge circuit and an electrical connection of the battery cells. 11. The method of claim 10,
Wherein the blocking signal generator outputs a signal for controlling the power switch to be opened when any one of the first comparator and the second comparator outputs an abnormal signal. 12. The method of claim 11,
Wherein the blocking signal generator includes any one of a latch, a flip-flop, and a sequential logic circuit. 11. The method of claim 10,
And a current controller for sensing an amount of current supplied to the battery cells to shut off the power switch when an overcurrent is detected. 11. The method of claim 10,
A temperature sensing unit for measuring a temperature of each battery cell; And
And a temperature controller for shutting off the power switch when the temperature measured by the temperature sensing unit is higher than a reference temperature.

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