KR100696673B1 - Battery management system and driving method thereof - Google Patents

Abstract

Provided are a battery maintenance system to allow a pack voltage to be measured more precisely and to reduce the number of devices, and a method for driving the battery maintenance system. The battery maintenance system comprises a sensing stabilization part which comprises a first signal wire and a second signal wire electrically connected to the first terminal and the second terminal of a battery and maintains the potential difference between the first signal wire and the second signal wire to be constant; an attenuation part which attenuates the potential difference between the first signal wire and the second signal wire to a certain size so as to output a pack voltage measurement signal; a noise removing part which receives the pack voltage measurement signal from the attenuation part to remove the noise of the pack voltage measurement signal; and an A/D converter which converts the pack voltage measurement signal output from the noise removing part into a digital value.

Description

Battery management system and driving method thereof

1 is a view schematically showing a vehicle system using electricity according to an embodiment of the present invention.

2 is a view schematically showing a sensing unit according to an embodiment of the present invention.

3 is a view schematically showing a pack voltage measurement unit according to an embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery management system, and more particularly, to a battery management system that can be used in an automobile using electric energy.

Automobiles using internal combustion engines that use gasoline or heavy oil as their main fuels have serious effects on pollution, such as air pollution. Therefore, in recent years, in order to reduce the occurrence of pollution, much efforts have been made in the development of electric vehicles or hybrid vehicles.

An electric vehicle is a vehicle operated by electric energy output from a battery. Such an electric vehicle uses no battery as a main power source because a plurality of secondary cells capable of charging and discharging are used as a pack has no exhaust gas and has a very small noise.

On the other hand, a hybrid vehicle is an intermediate vehicle between an automobile using an internal combustion engine and an electric vehicle, and a vehicle using two or more power sources such as an internal combustion engine and a battery. At present, a hybrid vehicle of a hybrid type has been developed, such as using a fuel cell that directly generates an electric energy by chemical reaction while continuously supplying an internal combustion engine and hydrogen and oxygen, or uses a battery and a fuel cell.

In the vehicle using electric energy as described above, the performance of the battery directly affects the performance of the vehicle. Therefore, the performance of each battery cell must be excellent, and each battery cell is measured by measuring the voltage of each battery cell, the voltage and current of the entire battery, and the like. There is an urgent need for a battery management system (BMS) capable of efficiently managing charge and discharge of cells.

Another technical problem to be achieved by the present invention is to provide a battery management system that can measure the pack voltage more precisely.

A battery management system according to an aspect of the present invention is a battery management system in which a plurality of battery cells are connected to a battery composed of one pack, the battery management system being electrically connected to first and second terminals of the battery, respectively. A sensing stabilization unit including a first signal line and a second signal line, the sensing stabilizing unit maintaining a constant difference between the first signal line and the second signal line; An attenuator for attenuating a potential difference between the first signal line and the second signal line to a predetermined magnitude and outputting a pack voltage measurement signal; A noise removal unit receiving the pack voltage measurement signal output from the attenuation unit and removing noise of the pack voltage measurement signal; And an A / D converter for converting the pack voltage measurement signal output from the noise removing unit into a digital value.

The noise removing unit may be a low pass filter including an OP AMP having an operation allowance range including the predetermined size, and may be connected to the first signal line and the second signal line of the sensing stabilization unit to respectively connect the first terminal and the first signal of the battery. The electronic device may further include a current controller configured to adjust an amount of current applied from the two terminals to the first signal line and the second signal line, respectively.

A battery management system according to another aspect of the present invention is a battery management system in which a plurality of battery cells are connected to a battery composed of one pack, and the plurality of cell voltage measurement signals by measuring cell voltages of the plurality of battery cells respectively. Cell voltage measuring unit for outputting; A pack voltage measuring unit configured to sense the pack voltage of the battery pack, attenuate the sensed pack voltage to a predetermined magnitude, and output a pack voltage measurement signal from which noise is removed; A pack current measuring unit measuring a pack current of the battery pack and outputting a pack current measuring signal; And an A / D converter which receives the cell voltage measurement signal, the pack voltage measurement signal, and the pack current measurement signal, and converts them into digital values.

The pack voltage measuring unit may include: an attenuator configured to output a signal obtained by attenuating the sensed pack voltage of the battery to the predetermined magnitude; And an noise remover configured to output a pack voltage measurement signal from which noise of the signal output from the attenuator is removed by using an OP AMP having an operation allowance range including the predetermined size.

A method of driving a battery management system according to another aspect of the present invention,

a) sensing a pack voltage of the battery; b) generating a pack voltage measurement signal obtained by attenuating the sensed pack voltage to a predetermined magnitude; And c) removing noise of the pack voltage measurement signal attenuated to the predetermined magnitude.

In step c), a noise of the pack voltage measurement signal may be removed using a low pass filter, and the low pass filter may include an OP AMP having an operation allowable range including the predetermined size.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention. Like parts are designated by like reference numerals throughout the specification.

Throughout the specification, when a part is "connected" to another part, this includes not only "directly connected" but also "electrically connected" with another element in between. . In addition, when a part is said to "include" a certain component, this means that it may further include other components, except to exclude other components unless otherwise stated.

1 is a view schematically showing a vehicle system using electricity according to an embodiment of the present invention.

As shown in FIG. 1, an automotive system includes a BMS 1, a battery 2, a current sensor 3, a cooling fan 4, a fuse 5, a main switch 6, and an engine controller unit (ECU). 7, an inverter 8 and a motor generator 9.

First, the battery 2 includes a plurality of subpacks 2a to 2h, an output terminal 2_OUT1, an output terminal 2_OUT2, and a subpack 2d and a subpack 2e in which a plurality of battery cells are connected in series. It includes a safety switch (2_SW) provided in. Here, the subpacks 2a to 2h are illustrated as eight by way of example, and the subpacks are merely displayed as a group of a plurality of battery cells, but are not limited thereto. In addition, the safety switch 2_SW is a switch provided between the subpack 2d and the subpack 2e and is a switch that can be manually turned on and off for the safety of the operator when replacing the battery or performing work on the battery. . In the present embodiment, the safety switch 2_SW is provided between the subpack 2d and the subpack 2e, but the present invention is not limited thereto. The output terminal 2_OUT1 and the output terminal 2_OUT2 are connected to the inverter 8.

The current sensor 3 measures the output current amount of the battery 2 and outputs it to the sensing unit 10 of the BMS 1. Specifically, the current sensor 3 may be a Hall CT (Hall current transformer) that measures current using a Hall element and outputs an analog current signal corresponding to the measured current.

The cooling fan 4 cools heat that may be generated by the charging and discharging of the battery 2 based on the control signal of the BMS 1, thereby preventing deterioration of the battery 2 and deterioration of the charging and discharging efficiency due to the temperature rise. do.

The fuse 5 prevents overcurrent from being transferred to the battery 2 by the disconnection or short circuit of the battery 2. That is, when an overcurrent occurs, the fuse 5 is disconnected to block the overcurrent from being transmitted to the battery 2.

The main switch 6 turns on and off the battery 2 based on a control signal of the BMS 1 or the ECU 7 of the vehicle when an abnormal phenomenon such as overvoltage, overcurrent, high temperature occurs.

The BMS 1 includes a sensing unit 10, a MCU (Main control unit) 20, an internal power supply unit 30, a cell balancing unit 40, a storage unit 50, a communication unit 60, and a protection circuit unit 70. , A power-on reset unit 80 and an external interface 90.

The sensing unit 10 measures a total battery pack current, a total battery pack voltage, each battery cell voltage, a cell temperature, and an ambient temperature, and transmits the same to the MCU 20.

The MCU 20 may charge a state of charging (hereinafter referred to as SOC) of the battery 2 based on the total battery pack current, the total battery pack voltage, each battery cell voltage, the cell temperature, and the ambient temperature received from the sensing unit 10. ), The state of health (hereinafter referred to as SOH), and the like, generate information informing the state of the battery 2 and transmit it to the ECU 7 of the vehicle. Therefore, the ECU of the vehicle performs charging or discharging of the battery 2 based on the SOC and SOH transmitted from the MCU 20.

The internal power supply unit 30 is a device that generally supplies power to the BMS 1 using an auxiliary battery. The cell balancing unit 40 balances the state of charge of each cell. That is, a cell with a relatively high state of charge can be discharged and a cell with a relatively low state of charge can be charged. The storage unit 50 stores current SOC, SOH, and the like when the power of the BMS 1 is turned off. The storage unit 50 may be an EEPROM as a nonvolatile storage device that can be electrically written and erased. The communication unit 60 communicates with the ECU 7 of the vehicle. The protection circuit unit 70 is a circuit for protecting the battery 2 from external shock, overcurrent, low voltage, etc. using firmware. The power-on reset unit 80 resets the entire system when the power of the BMS 1 is turned on. The external interface 90 is a device for connecting the auxiliary devices of the BMS such as the cooling fan 4 and the main switch 6 to the MCU 20. In the present embodiment, only the cooling fan 4 and the main switch 6 are shown, but are not limited thereto.

The ECU 7 determines the torque degree based on the information of the accelerator, break, vehicle speed, etc. of the vehicle, and controls the output of the motor generator 9 to match the torque information. That is, the ECU 7 controls the switching of the inverter 8 so that the output of the motor generator 9 matches the torque information. In addition, the ECU 7 receives the SOC of the battery 2 delivered from the MCU 20 through the communication unit 60 of the BMS 1 so as to control the SOC of the battery 2 to be a target value (for example, 55%). do. For example, when the SOC transmitted from the MCU 20 is 55% or less, the switch of the inverter 8 is controlled so that the power is output in the direction of the battery 10 to charge the battery 2, and the pack current I is Is a '-' value. On the other hand, when the SOC is 55% or more, the switch of the inverter 8 is controlled so that power is output in the direction of the motor generator 9 so that the battery 2 is discharged. At this time, the pack current I becomes a '+' value.

The inverter 8 causes the battery 2 to be charged or discharged based on the control signal of the ECU 7.

The motor generator 9 drives the motor vehicle based on the torque information transmitted from the ECU 7 using the electric energy of the battery 2.

As a result, the ECU 7 charges and discharges as much as the power capable of charging and discharging based on the SOC, thereby preventing the battery 2 from being overcharged or overdischarged so that the battery 2 can be efficiently used for a long time. However, since the actual SOC of the battery 2 is difficult to measure after the battery 2 is mounted in the vehicle, the BMS 1 uses the pack current sensed by the sensing unit 10, the pack voltage, and the like to measure the SOC. It must be accurately estimated and delivered to the ECU 7.

2 is a view schematically showing a sensing unit 10 according to an embodiment of the present invention.

As shown in FIG. 2, the sensing unit 10 includes a control signal generator 110, a cell voltage measuring unit 120, a pack voltage measuring unit 130, a pack current measuring unit 140, and a temperature measuring unit ( 150 and A / D converter 160.

The control signal generator 110 generates a control signal and sequentially outputs the control signal to the cell voltage measurement unit 120 so that the cell voltage measurement unit 120 may sequentially measure the voltages of the 40 battery cells.

The cell voltage measurement unit 120 measures analog cell voltages of 40 battery cells 211 to 285 of the battery 2 and outputs the analog cell voltages to the A / D converter 160.

The pack voltage measuring unit 130 measures an analog voltage value between the output terminal 291 (see FIG. 1) and the output terminal 292 (see FIG. 1) of the battery 2 and outputs the analog voltage value to the A / D converter 160. .

The pack current measuring unit 140 receives the current value measured by the current sensor 3 (see FIG. 1), converts the current value into an analog voltage signal, and outputs the analog voltage signal to the A / D converter 160.

The A / D converter 160 converts the analog values received from the cell voltage measuring unit 120, the pack voltage measuring unit 130, and the pack current measuring unit 140 into digital data to convert the MCU 20 (see FIG. 1). Will output Specifically, the A / D converter 160 includes 10 input terminals and sequentially converts analog data input from the input terminals into digital data one by one. Here, eight input terminals (called input terminals 1 to 8) among the ten input terminals are connected to the output terminals of the cell voltage measuring unit 120, and the other input terminal (called input terminal 9) is a pack voltage. It is connected to the measuring unit 130, the other input terminal (referred to as the input terminal 10) is connected to the pack current measuring unit 140.

In addition, the temperature measuring unit 150 outputs a digital value measuring the temperature in the battery 2 and the ambient temperature to the MCU 20.

3 is a view schematically showing a pack voltage measuring unit 130 according to an embodiment of the present invention.

As shown in FIG. 3, the pack voltage measurer 130 includes a sensing stabilizer 131, a current adjuster 132, an attenuator 133, and a noise remover 134.

The sensing stabilizer 131 includes a resistor 131a and a capacitor 131b. The resistor 131a and the capacitor 131b include a signal line 131+ connected to the positive output terminal 291 of the battery 2 and a signal line 132- connected to the negative output terminal 292 of the battery 2. ) Is connected in parallel to maintain the potential difference between the signal line 131+ and the signal line 131-. For example, even if noise is input to the signal line 131+ and the signal line 131- so that the potentials of the signal line 131+ and the signal line 131- are shaken based on the noise, the resistor 131a and the capacitor 131b are It functions to keep the potential difference between the signal line 131+ and the signal line 131- constant.

The current controller 132 adjusts the amount of current applied to the signal line 131+ and the signal line 131-from the output terminal 291 and the output terminal 292 of the battery 2. The current controller 132 includes a resistor 132a connected in series to the signal line 131+ and a resistor 132b connected in series to the signal line 131-. For example, when the total pack voltage of the battery 2 is 200V, the current can be set to 0.1 mA by using the resistor 132a and the resistor 132b of 2 kHz. In the present embodiment, the resistors 132a and 132b each use one 2 kΩ resistor, but two 1 k resistors may be connected in series.

The attenuator 133 is a pack voltage measurement signal generator that generates a signal corresponding to the pack voltage of the battery 2, and includes a resistor 133a connected to the ground electrode, a capacitor 133b connected to the ground electrode, and a differential amplifier. 133c. The differential amplifier 133c is an inverted differential amplifier. The ground potential is input to the (+) input terminal through the resistor 133a and the capacitor 133b, and the battery is connected to the (-) input terminal through the resistor 132a of the current control unit 132. The potential of the positive output terminal 291 of (2) is input, and outputs a pack voltage measurement signal to the output terminal 133d based on the voltage difference between the two inputs. The pack voltage magnitude of the battery 2 input through the signal line 131+ becomes a pack voltage measurement signal having a magnitude of 0 to 5V by the attenuator 133.

The noise removing unit 134 removes noise from a signal output from the output terminal 133d of the attenuator 133. As the noise removing unit 134, a low pass filter including an operational amplifier 134a may be used. The analog cell voltage output from the noise removing unit 134 is input to the ninth input terminal of the A / D converter 160 and converted into a digital value.

The pack voltage of the battery 2 sensed by the pack voltage measuring unit 130 is generally 0 to 200V. On the other hand, as the allowable voltage of the OP AMP 134a of the noise removing unit 134 is -15V to 15V as shown in FIG. 3, voltage attenuation is necessary.

On the other hand, conventionally, the voltage inputted to the OP AMP of the noise removing unit of the pack voltage measuring unit through the voltage divider without the attenuator. However, when the voltage divider is used, a voltage drop occurs due to the voltage divider, and there is a problem that the precision of the pack voltage measurement is deteriorated.

However, according to the present invention, since the measured pack voltage is input to the noise removing unit 134 through the attenuation unit 133, the size of the pack voltage of the battery 2 is changed to the OP of the noise removing unit 134 without any voltage division. It can be reduced within the allowable voltage range of the AMP 134a. Therefore, it is possible to prevent the occurrence of voltage drop due to voltage division and to further improve the precision of the pack voltage measurement.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

According to the present invention, the pack voltage can be measured more accurately by reducing the magnitude of the pack voltage sensed by the pack voltage measuring unit and then removing the noise.

In addition, since the voltage dividing of the sensed pack voltage is unnecessary by reducing the magnitude of the pack voltage sensed by the pack voltage measuring unit and removing the noise, the number of elements required for the voltage dividing may be reduced.

Claims (8)

In a battery management system in which a plurality of battery cells are connected to a battery consisting of one pack, A sensing stabilization unit including a first signal line and a second signal line electrically connected to the first terminal and the second terminal of the battery, respectively, and maintaining a potential difference between the first signal line and the second signal line; An attenuator for attenuating a potential difference between the first signal line and the second signal line to a predetermined magnitude and outputting a pack voltage measurement signal; A noise removal unit receiving the pack voltage measurement signal output from the attenuation unit and removing noise of the pack voltage measurement signal; And A / D converter for converting the pack voltage measurement signal output from the noise removing unit into a digital value Battery management system comprising a. The method of claim 1, The noise removing unit And a low pass filter including an OP AMP having an operation allowance range including the predetermined size. The method of claim 2, A current adjusting unit connected to the first signal line and the second signal line of the sensing stabilization unit to adjust an amount of current applied from the first terminal and the second terminal of the battery to the first signal line and the second signal line, respectively; Battery management system further comprising. In a battery management system in which a plurality of battery cells are connected to a battery consisting of one pack, A cell voltage measurement unit measuring cell voltages of the plurality of battery cells and outputting a plurality of cell voltage measurement signals; A pack voltage measuring unit configured to sense the pack voltage of the battery pack, attenuate the sensed pack voltage to a predetermined magnitude, and output a pack voltage measurement signal from which noise is removed; A pack current measuring unit measuring a pack current of the battery pack and outputting a pack current measuring signal; And An A / D converter that receives the cell voltage measurement signal, the pack voltage measurement signal, and the pack current measurement signal and converts them into digital values, respectively Battery management system comprising a. The method of claim 4, wherein The pack voltage measurement unit, An attenuator configured to output a signal obtained by attenuating the sensed pack voltage of the battery to the predetermined magnitude; And A noise removing unit for outputting a pack voltage measurement signal from which noise of a signal output from the attenuation unit is removed by using an OP AMP having an operation allowance range including the predetermined size. Battery management system comprising a. In the driving method of a battery management system that a plurality of battery cells are connected to a battery consisting of one pack, a) sensing a pack voltage of the battery; b) generating a pack voltage measurement signal obtained by attenuating the sensed pack voltage to a predetermined magnitude; And c) removing noise of the pack voltage measurement signal attenuated to the predetermined magnitude; Method of driving a battery management system comprising a. The method of claim 6, In step c), A method of driving a battery management system to remove noise of the pack voltage measurement signal using a low pass filter. The method of claim 7, wherein And the low pass filter includes an OP AMP having an operation allowable range including the predetermined size.

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