Battery pack and charging method

Battery pack and its charging method

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application requires Korean Patent Application No. 10-2008-0052276 filed with the Korean Intellectual Property Office on June 3, 2008, entitled "BatteryPack and Charging Method for the Same (Battery Pack and Charging Method for the Same) Priorities and rights, the entire contents of which are incorporated here by reference.

Technical field

[0003] Exemplary embodiments relate to a battery pack and a charging method thereof. More specifically, exemplary embodiments relate to a battery pack and a charging method thereof that automatically adjust the charging current provided by a charger to ensure stability.

Background technique

[0004] A conventional battery pack may include a battery such as a lithium ion battery or a lithium polymer battery and a stability circuit electrically connected to the battery. A conventional battery may include an electrode assembly and an electrolyte sealed in its case, and may be charged/discharged through a chemical reaction. The stability circuit of a conventional battery pack can prevent overcharge/overdischarge of the battery by adjusting the charge-discharge process of the battery.

[0005] Not to mention that when the conventional battery pack is electrically connected to the charger, before the charging of the battery starts, the magnitude of the charging current may be a predetermined value set by the charger. As a result, regardless of external conditions, for example, the temperature of the surrounding environment is very low in winter and/or the temperature of the surrounding environment is very high in summer, the conventional battery pack may always be charged with the same charging current. In other words, even if the external conditions change, such as when the ambient temperature around the battery pack is very low or very high, and the charging characteristics of the battery pack change relative to the external conditions, for example, the internal resistance of the battery pack changes according to low/high temperature, conventional battery packs It is also charged with the same predetermined charging current from the charger.

[0006] For example, when a conventional battery pack is charged in a high-temperature environment, such as inside a vehicle in summer, the internal heat radiation of the battery pack may increase. Therefore, when the charging current continuously flows from the charger into the battery pack with increased internal heat radiation, the circuit devices of the battery pack may be damaged due to the internal heat radiation. In another example, when a conventional battery pack is charged in a low-temperature environment, such as inside a vehicle in winter, a charging current with a pulse component may instantaneously flow into the battery pack, thereby damaging the circuit devices of the battery pack.

Summary of the invention

[0007] Therefore, exemplary embodiments aim at a battery pack and a charging method thereof, which basically overcome one or more shortcomings and shortcomings of the related art.

[0008] Therefore, a feature of the exemplary embodiment is to provide a battery pack having a battery, the battery pack having a structure capable of automatically adjusting the charging current provided by the charger to the battery to ensure stability.

[0009] Another feature of the exemplary embodiment is to provide a method for charging a battery pack, which ensures stability by automatically adjusting the charging current provided by the charger to the battery pack.

[0010] At least one of the above and other features can be achieved by providing a battery pack that includes: a battery including a positive electrode and a negative electrode; a switch module including a charge switch device and a discharge switch device, the charge The switching device and the discharge switching device are electrically connected to the high current path of the battery; and are electrically connected to the switching module

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The battery management unit (BMU), the BMU is configured to: adjust the limit value of the charging current provided by the charging switch device, and set the size of the charging current provided by the charging switch device to be equal to or less than the adjusted Limit value.

[0011] The limit value of the charging current may be changed and set according to the temperature change of the battery, and the BMU may charge the battery so that the charging current of the battery does not exceed the limit value of the charging current.

[0012] The limit value of the charging current may be set so that the charging rate of the battery may be about 100% at a temperature in the range of about 18° C. to about 30° C., at a temperature outside the range The down can be less than about 100%.

[0013] The battery pack may include a temperature sensor electrically connected to the BMU and the high current path; and a voltage of the high current path electrically connected to the charging switch device, the BMU, and the battery Smoothing circuit. In this case, the BMI can apply a pulse width modulation (PWM) signal to the voltage smoothing circuit, and can adjust the duty cycle of the PWM signal according to the temperature measured by the temperature sensor. The charging current of the charging switch device.

[0014] In this case, the temperature sensor may be a thermistor, and the BMU may detect the temperature of the battery by detecting the resistance change rate of the thermistor.

[0015] The voltage smoothing circuit may convert the PWM signal into direct current (DC), and the BMU may adjust the DC by adjusting the duty cycle of the PWM signal.

[0016] The charging switch device may include a field effect transistor (FET) having a source, a drain, and a gate, the source and the drain are electrically connected to the high current path of the battery, the The gate is electrically connected to the BMU. In this case, the DC voltage output by the voltage smoothing circuit may be applied to the gate and the source.

[0017] The voltage smoothing circuit may include a resistor electrically connected to the gate and the BMU, and electrically connected to the gate and the BMU between the gate and the source. Source capacitor. In this case, the voltage smoothing circuit may further include a buffer resistor electrically connected to the capacitor in parallel.

[0018] The battery pack may further include a current detection device, wherein the BMU may be electrically connected to the current detection device in order to calculate the current flowing on the high current path of the battery.

[0019] The current detection device may include a sensing resistor, and the BMU can learn the reference voltage across the sensing resistor, and can detect the difference between the voltages across the sensing resistor. Change the value to detect the current flowing in the high current path of the battery.

[0020] The BMU may include: electrically connected to the battery to detect the open circuit voltage of the battery and electrically connected to the voltage smoothing circuit to turn on or off the charging switch device and the discharge switch An analog front end of the device; and a microprocessor unit electrically connected to the analog front end, and the microprocessor unit can control the current of the charging switch device by applying a PWM signal to the analog front end.

[0021] The analog front end may include: a voltage detector electrically connected to the battery to detect the open circuit voltage of the battery, the battery having an overdischarge mode that can be determined according to the open circuit voltage of the battery, complete A discharge mode, a full charge mode, and an overcharge mode; and a power drive circuit for turning on or off the charging switching device and the discharging switching device.

[0022] The power drive circuit can amplify the applied PWM signal generated in the microprocessor unit and can provide amplified power to the charging switch device and the discharge switch device.

[0023] The analog front end may be an application specific integrated circuit (ASIC).

[0024] At the same time, the maximum rated power of the charging switch device can take into account the charging voltage and the charging voltage of the charger.

The open circuit voltage of the battery and the limit value of the charging current are set, and can be set to about 80% to about 80% of the power obtained by multiplying the voltage difference and the charging current flowing in the high current path of the battery. Within 120%, wherein the voltage difference is obtained by subtracting the open circuit voltage from the charging voltage.

[0025] After keeping the initial current of the charging switch device low for a predetermined period of time during the initial charging operation of the battery, the BMU may increase the charging capacity of the battery after the predetermined period of time has elapsed. The charging current precharges the battery.

[0026] The charging switching device may include a charging FET electrically connected to the high current path of the battery, and a charging FET electrically connected to the charging FET in parallel and connected in a direction opposite to the charging current The parasitic diode.

[0027] The discharge switching device may include a discharge FET electrically connected to a high current path of the battery, and a discharge FET electrically connected to the discharge FET in parallel and connected in a direction opposite to the discharge current The parasitic diode.

[0028] At least one of the above and other features can also be achieved by providing a charging method for a battery pack having a battery including a positive electrode and a negative electrode, the method comprising: managing the battery The unit (BMU) is electrically connected to the switch module, the switch module includes a charge switch device and a discharge switch device, the charge switch device and the discharge switch device are electrically connected to the high current path of the battery; The temperature of the battery sets the limit value of the charging current provided by the charging switch device to the battery; and the magnitude of the charging current provided by the charging switch device to the battery is automatically adjusted so that the magnitude of the charging current is equal to or It is smaller than the adjusted limit value set by the BMU.

[0029] At least one of the above and other features can also be achieved by providing a method for charging a battery pack, the method comprising: detecting the temperature and current of the battery; and comparing the detected current with the detected current Comparing with the value set by the limit value of the charging current at the reached temperature, the limit value changes with the temperature; and adjusting the charging current of the battery so that the charging current of the battery does not exceed the limit value of the charging current.

[0030] The adjusting the charging current of the battery may include: determining whether the detected current of the battery is above a hysteresis zone, the hysteresis having a positive deviation and a negative deviation relative to the current value at a given temperature; And when the detected current of the battery is above the hysteresis zone at the detected temperature, the charging current is reduced to be below the hysteresis zone.

[0031] The adjusting the charging current of the battery may include: after calculating the power consumption of the charging switch device, determining whether the power consumption of the charging switch device exceeds a limit power setting value; and when the charging switch When the power consumption of the device exceeds the limit power setting value, the charging current is reduced to be below a certain threshold.

[0032] The power consumption of the charging switch device can be set according to the charging voltage of the charger, the open circuit voltage of the battery, and the limit value of the charging current, and can be set by changing the charging voltage from the charging voltage. The voltage difference obtained by subtracting the open circuit voltage is obtained by multiplying the charging current.

Description of the drawings

[0033] The above and other features and advantages will be more apparent to those of ordinary skill in the art by describing the exemplary embodiments in detail with reference to the accompanying drawings, in which:

[0034] FIG. 1 shows a block diagram of a battery pack according to an exemplary embodiment;

[0035] FIG. 2 shows an example of a lookup table in the MPU of FIG. 1;

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[0036] FIG. 3 shows a graph of the lookup table of FIG. 2;

[0037] FIG. 4 illustrates a flowchart of a charging method for a battery pack according to an exemplary embodiment; and

[0038] FIG. 5 shows a detailed flowchart of FIG. 4.

Detailed ways

[0039] Hereinafter, exemplary embodiments will be described more fully with reference to the accompanying drawings, however, they can be implemented in different forms, but they should not be construed as limiting the embodiments presented here. On the contrary, these embodiments are provided so that the disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art.

[0040] In the drawings, for clarity of illustration, the sizes of elements and regions may be enlarged. When it is mentioned that an element is "between" two elements, it will be understood that the element may be the only element between the two elements, or one or more intervening elements may also be present. When it is mentioned that an element is "connected to" another element, it will also be understood that the element may be directly connected to the other element, or another element may also be present between them. The same reference numerals always refer to the same elements.

[0041] As used herein, the term "a" is an open-ended term that can be used in conjunction with singular items or plural items.

[0042] FIG. 1 shows a block diagram of a battery pack according to an exemplary embodiment.

[0043] As shown in FIG. 1, a battery pack 100 according to an exemplary embodiment may include a battery 110, a switch module 120, and a battery management unit (BMU) 130. The battery pack 100 may further include a voltage smoothing circuit 140, a temperature sensor 150, a current detection device 160, and a positive terminal 171 and a negative terminal 172 that may be electrically connected to a charger or an external load. The battery pack 100 may further include a first auxiliary terminal 181 and a second auxiliary terminal 182 electrically connected to the microprocessor unit 132 for communication with external devices.

[0044] The battery 110 may be a rechargeable battery having a positive electrode 111 and a negative electrode 112. For example, the battery 110 may be a lithium ion battery or a lithium polymer battery, and may have an electrode assembly and an electrolyte sealed in its case. It is noted that although FIG. 1 shows only one battery 110, any suitable number of batteries 110 may be provided in the battery pack 100, such as multiple batteries.

[0045] The switching module 120 may include a charging switching device 121 and a discharging switching device 122. The charging switching device 121 may include a charging field effect transistor (FET) 121a and a parasitic diode 121b for the charging FET 121a. The discharge switching device 122 may include a discharge FET 122a and a parasitic diode 122b for the discharge FET 122a.

[0046] The charging FET 121a of the charging switching device 121 may have a drain 121D and a source 121S arranged on the high current path 10 of the battery 110. The charging FET 121a may have a gate 121G electrically connected to the analog front end 131, and may be turned on or off through a control signal input from the analog front end 131. When a charger (not shown) is electrically connected to the positive terminal 171 and the negative terminal 172, the charging FET 121a may be turned on to apply the charging current of the charger to the battery 110.

[0047] The parasitic diode 121b of the charging switching device 121 may be electrically connected to the charging FET 121a in parallel. The parasitic diode 121b may be connected in the opposite direction to the charging current. When the battery 110 is fully charged, the parasitic diode 121b can cut off the charging current path. Therefore, when the battery 110 is fully charged, the parasitic diode 121b can only pass the discharge current, so the battery 110 can be prevented from being overcharged. Therefore, the stability of the battery 110 can be improved.

[0048] The discharge FET 122a of the discharge switching device 122 may have a drain 122D and a source 122S arranged on the high current path 10 of the battery 110. The discharge FET 122a may have a gate 122G electrically connected to the analog front end 131,

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And it can be turned on or off by a control signal input from the analog front end 131. The discharge FET 122a may be turned on to apply a discharge current to the external load electrically connected to the positive terminal 171 and the negative terminal 172.

[0049] The parasitic diode 122b of the discharge switching device 122 may be electrically connected to the discharge TET 122a in parallel. The parasitic diode 122b may be connected in the opposite direction to the discharge current. When the battery 110 is completely discharged, the parasitic diode 122b can cut off the discharge current path. Therefore, when the battery 110 is completely discharged, the parasitic diode 122b can only pass the charging current, so the battery 110 can be prevented from being over-discharged. Therefore, the stability of the battery 110 can be improved.

[0050] The BMU 130 may include an analog front end 131 and a microprocessor unit (MPU) 132. The analog front end 131 may include a voltage detector 131a and a power driving circuit 131bo

[0051] The voltage detector 131a of the analog front end 131 may be electrically connected to the positive electrode 111 and the negative electrode 112 of the battery 110. The voltage detector 131a may be a voltage detection circuit, for example, a voltage comparator. The voltage detector 131a may detect the voltage difference between the positive electrode 111 and the negative electrode 112 of the battery 110 to determine whether the mode of the battery 110 is an overdischarge mode, a full discharge mode, a full charge mode, or an overcharge mode according to the voltage of the battery 110. According to the mode of the battery 110, the voltage detector 131a may output a high-level control signal to the power driving circuit 131b to turn on the switch module 120, or may output a low-level control signal to turn off the switch module 120.

[0052] The power driving circuit 131b of the analog front end 131 may control the switch module 120 according to the output signal received from the voltage detector 131a. The power driving circuit 131b may include a charging power driving circuit 131b1 and a discharging power driving circuit 131b2o.

[0053] The charging power driving circuit 131b1 may be electrically connected to the gate 121G of the charging FET 121a in order to turn on or off the charging FET 121a. The charging power driving circuit 131b 1 may be electrically connected to the voltage detector 131a. Therefore, the charging power driving circuit 131b 1 can turn on or off the charging switching device 121 in response to the output signal of the voltage detector 131a according to the mode of the battery 110.

[0054] The charging power driving circuit 131b1 may be electrically connected to the MPU 132 in order to receive a pulse width modulation (PWM) signal output by the MPU 132, and may amplify the PWM signal. The charging power driving circuit 131b1 may output the amplified PWM signal to the voltage smoothing circuit 140. In other words, the charging power driving circuit 131b1 can amplify the high-level control signal output by the voltage detector 131a in order to turn on/off the charging switch device 121. The charging power driving circuit 131b1 can amplify the PWM signal output by the MPU 132, and can adjust the charging current of the charging switch device 121. The charging power driving circuit 131bl may be a switching circuit, such as a C-MOS FETo

[0055] The discharge power driving circuit 131b2 may be electrically connected to the gate 122G of the discharge FET 122a in order to turn on or off the discharge FET 122a. The discharge power driving circuit 131b2 may be electrically connected to the voltage detector 131a, and may turn on or off the discharge switching device 122 in response to the output signal of the voltage detector 131a according to the mode of the battery 110. The discharge power driving circuit 131b2 may be a switching circuit, such as C-MOS FETo

[0056] The analog front end 131 may be an application specific integrated circuit (ASIC) for immediately detecting the voltage of the battery 110 and driving the switch module 120 according to the voltage of the battery 110. Therefore, the analog front end 131 can work with a very fast response speed according to the mode of the battery 110, that is, the detected voltage of the battery Π0, so the battery 110 can be protected by the switch module 120 immediately driving, that is, on/off. .

[0057] Because the maximum rated power of the charging switching device 121 controlled by the charging power driving circuit 131b1 of the analog front end 131 can increase as the current increases, the analog front end 131, that is, the power driving circuit device driving the charging switching device 121 requires The power consumption can also be increased. However, because the power consumption of the analog front end 131, that is, the power driving ASIC, can be predetermined before it is connected to the battery pack 100, the maximum rated power of the charging switch device 121 can be stabilized

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Tones. Ground adjustment. In other words, according to an exemplary embodiment, the maximum rated power of the charging switch device 121 may be set according to the charging voltage of the charger, the voltage of the battery 110, and the charging current in the high current path 10 so as to correspond to the predetermined value of the analog front end 131 Power consumption.

[0058] In more detail, the maximum rated power of the charging switching device 121 may be set to about 80% to about 120% of the calculated power consumption of the charging switching device 121. The calculated power consumption of the charging switch device 121 may be obtained by multiplying the charging current and the voltage difference between the charger voltage and the voltage of the battery 110. In this regard, it is noted that the charging current refers to the current flowing in the high current path 10 of the battery Π0, and the charger voltage refers to the charging voltage of the charger electrically connected to the positive terminal 171 and the negative terminal 172, The voltage of the battery 110 refers to the open circuit voltage of the battery 110 measured between the positive electrode 111 and the negative electrode 112.

[0059] The maximum rated power of the charging switch device 121 can be set to about 80% or higher of the calculated power consumption of the charging switch device 121, so a sufficient amount of charging/discharging current can be in the high current path of the battery 110 10 flows in. The maximum rated power of the charging switching device 121 can be set to about 120% or less of the calculated power of the charging switching device 121, so the switching operation of the analog front end 131, that is, the driving of the charging switching device 121 can be smoothly performed .

[0060] The MPU 132 of the BMU 130 may include a microprocessor (not shown), a memory (not shown) that may be electrically connected to the microprocessor, a passive device (not shown), and an active device (not shown) Out). The MPU 132 may be electrically connected to the analog front end 131, and may receive voltage information of the battery 110 and detect the voltage of the battery 110. The MPU 132 may calculate the charging current flowing in the high current path 10 of the battery 110 during the charging/discharging of the battery 110. In detail, the MPU 132 may be electrically connected to both ends of the current detecting device 160, and the charging current in the high current path 10 may be calculated by measuring the change in the voltage difference between the both ends of the current detecting device 160. The current detection device 160 may be arranged on the high current path 10 of the battery 110, and may include, for example, a sensing resistor. The BMU 130 may receive the reference voltage across the sensing resistor so as to determine the current flowing in the high current path 10 of the battery 110 by detecting a change in the difference between the voltage across the sensing resistor.

[0061] The MPU 132 can set a limit value of the charging current provided by the charging switch device 121. The MPU 132 can generate a PWM signal to be transmitted to the charging power driver circuit 131b1, so the charging power driver circuit 131b1 can drive the charging switching device 121 for the PWM signal so as to keep the charging current within the limit value of the charging current set by the MPU 132. In detail, the charging power driving circuit 131b1 may amplify the PWM signal, and may apply the amplified PWM signal to the voltage smoothing circuit 140. The limit value of the charging current may be set to provide stability to the battery pack 100, that is, the battery 110 is charged with a low current when the battery pack 100 is at a low temperature or a high temperature.

[0062] The MPU 132 may be electrically connected to the temperature sensor 150, and may detect the temperature of the battery 110. The limit value of the charging current may be adjusted according to the temperature of the battery 110, as will be described in more detail with reference to FIGS. 2 to 3 below.

[0063] FIG. 2 shows a temperature/current correlation lookup table in the MPU 132. Fig. 3 shows a current/temperature graph of the look-up table of Fig. 2. As shown in FIG. 2 and FIG. 3, the limit value 133a of the charging current can be changed according to changes in temperature.

[0064] In detail, the temperature sensor 150 may be electrically connected to the high current path 10 of the MPU 132 and the battery 110. For example, the temperature sensor 150 may be a thermistor. The MPU 132 can detect the resistance change rate of the thermistor, and can use the resistance change in order to detect the temperature of the battery 110, that is, corresponding to the temperature change outside the battery pack 100.

[0065] For example, as shown in FIG. 2, the MPU 132 may include a battery 110 in the range of about 0°C to about 60°C.

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The look-up table of the temperature change. In the look-up table in FIG. 2, the charging rate refers to the percentage of the actual charging capacity of the battery 110 relative to the total power capacity of the battery 110. As shown in FIG. 2, the limit value of the charging current of about 4A corresponding to the charging rate of about 100% can flow at about 20°C under atmospheric pressure. As further shown in FIG. 2, the limit value of the charging current of about 3.6A corresponding to the charging rate of about 90% can flow at about 0°C and 40°C, that is, low temperature. As further shown in FIG. 2, the limit value of the charging current of about 3.2A corresponding to the charging rate of about 80% can flow at about 60°C, that is, at a high temperature. In other words, the battery 110 may be supplied with a current having a limit value of about 4A, as a charging current that maintains a charging rate of about 100% at room temperature, and may be supplied with a current having a limit value of less than about 4A, As a charging current that maintains a charging rate of less than about 100% at a high temperature and a low temperature, that is, at a temperature below and/or above room temperature.

[0066] In this regard, it is noted that room temperature refers to a temperature of about 18°C to about 30°C, for example, about 20°C. Further, the temperature of about 0°C to about 40°C is only an exemplary temperature range, and an exemplary embodiment may include a temperature range of about (-20)°C to about 120°C. For example, the low temperature may include a temperature below room temperature, for example, about 10Ό to about (-20)Ό, and the high temperature may include a temperature above room temperature, for example, about 30°C to about 120Ό. It is further noted that about 80% to about 100% The charging rate of is only an exemplary charging rate range, and the embodiment may include a charging rate of about 50% to about 100% according to the temperature change of the battery 110 from about (-20) °C to about 120 °C.

[0067] By changing the duty cycle of the PWM signal applied to the analog front end 131, the MPU 132 can adjust the charging current according to the look-up table, thereby preventing the current flowing through the charging switch device 121 from exceeding the charging current limit value 133a in the look-up table. Therefore, the battery pack 100 can be charged with a low current even in a low temperature or high temperature environment, thereby ensuring stability. In this case, the duty ratio may refer to the ratio between the period of time required to maintain the high-level state and the period of one cycle of the PWM signal with the pulse wave.

[0068] The MPU 132 may perform a pre-charging operation for reducing the initial current amount in the charging switching device 121 during a predetermined period of time during the initial charging of the battery 110. More specifically, when the charger is electrically connected to the positive terminal 171 and the negative terminal 172, regardless of the internally set limit value of the charging current, the MPU 132 may occasionally provide an excessive charging current to the battery 110, for example, at a high temperature, such as high Current pulse. As a result, when the battery 110 is supplied with a large amount of current in a very short period of time, the battery may malfunction, such as exhibiting internal deterioration and/or short life. In order to prevent this phenomenon, the MPU 132 according to an exemplary embodiment may be set to automatically reduce the initial current amount of the charging switching device 121 during a predetermined period of time during the initial charging of the battery 110, for example, during the predetermined period of time, the initial The amount of current can be set to a value smaller than the limit value of the charging current, thereby achieving a stable supply of the charging current. After the pre-charging operation of the battery 110, that is, after a predetermined period of time, the MPU 132 can adjust the current to the limit value of the charging current according to the values in FIGS. 2 to 3, so as to continue charging the battery 110, thereby ensuring the stability of the battery 110 Sex.

[0069] The voltage smoothing circuit 140 may include a resistor 141 and a capacitor 142. The voltage smoothing circuit 140 may further include a buffer resistor 143.

[0070] The resistor 141 may be electrically connected to the gate 121G of the charging FET 121a and the BMU 130. The capacitor 142 may be electrically connected to the gate 121G of the charging FET 121a and the source 121S of the charging FET 121a. The voltage smoothing circuit 140 may change the PWM signal amplified and output by the charging power driving circuit 131b1 into a direct current (DC) voltage, so the DC voltage may be applied between the gate 121G and the source 121S of the charging FET 121a.

[0071] In this case, a negative voltage difference may be formed between the gate 121G and the source 121S of the charging FET 121a. When the MPU 132 increases the duty ratio of the PWM signal, the magnitude of the DC voltage applied to the gate 121G and the source 121S of the charging FET 121a may increase, so there is a negative voltage difference between the gate 121G and the source 121S of the charging FET 121a

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It may decrease, and the amount of current flowing from the source 121S to the drain 121D may increase.

[0072] On the other hand, when the MPU 132 reduces the duty ratio of the PWM signal, the magnitude of the DC voltage applied to the gate 121G and the source 121S may decrease. Therefore, the negative voltage between the gate 121G and the source 121S of the charging FET 121a may increase, and the amount of current flowing from the source 121S to the drain 121D may decrease.

[0073] The buffer resistor 143 may be electrically connected to the capacitor 142 in parallel. The buffer resistor 143 can absorb the pulse component of the PWM signal amplified by the charging power driving circuit 131b1, thereby protecting the charging FET 121a. The buffer resistor 143 may generate a negative voltage difference between the gate 121G and the source 121S of the charging FET 121a to adjust the amount of initial current flowing from the source 121S to the drain 121D of the charging FET 121a.

[0074] Hereinafter, the driving operation of the battery pack 100 during charging of the battery 110 will be described in detail.

[0075] For example, suppose that the voltage of the battery 110 is 0.9V, the analog front end 131 is in an overdischarge mode, and the power of the analog front end 131 and the MPU 132 are disconnected in order to reduce power consumption.

[0076] When the charger is electrically connected to the positive terminal 171 and the negative terminal 172 of the battery pack 100 to provide charging current, the mode of the analog front end 131 can be changed from the over-discharge mode to the full-discharge mode, and the charge switching device 121 can pass through The analog front end 131 is turned on. In this case, the MPU 132 may apply the PWM signal to the charging power driving circuit 131b1 of the analog front end 131 from the point in time when the charger is electrically connected to the positive terminal 171 and the negative terminal 172 so as to provide a charging current. Next, the charging power driving circuit 13lb 1 may apply the amplified PWM signal to the voltage smoothing circuit 140, so the voltage smoothing circuit 140 may convert the PWM signal into a DC voltage to be applied to the gate 121G and the source 121S of the charging FET 121a . Note that within a predetermined period of time from the moment when the charger is connected to the positive terminal 171 and the negative terminal 172, the MPU 132 can initially output a duty cycle of about 90% of the PWM signal, thereby charging with a lower charging current. The switching device 121 is precharged. After the predetermined period of time has elapsed, the MPU 132 may reduce the duty ratio of the PWM signal by about 50% in order to provide the charging current to the charging switch device 121 at the operating level. The pre-charging operation of the battery 110, that is, providing a lower initial current, can prevent the battery 110 from deteriorating.

[0077] Once the battery 110 is precharged, the MPU 132 can use the temperature sensor 150 to detect the temperature of the battery 110, and can use the current detection device 160 to detect the charging current flowing in the high current path 10 of the battery 110. In order to determine the limit value of the charging current corresponding to the detected temperature and charging current, the MPU 132 may refer to a look-up table, such as the look-up table of the temperature-current table in FIG. 2. Temperature and current can be continuously monitored, so the limit value of charging current can be calculated and adjusted continuously.

[0078] For example, when the detected temperature and charging current of the battery 110 exceed the corresponding limit value 133a of the charging current in the look-up table of FIG. 2, the MPU 132 may increase the duty cycle of the PWM. Therefore, the negative DC voltage applied between the gate 121G and the source 121S of the charging FET 121a may increase, and the current flowing from the source 121S to the drain 121D of the charging FET 121a may decrease. Then, the charging current can be reduced to a value smaller than the limit value 133a of the charging current in the look-up table of FIG. 2, so as to ensure the stability of the battery 110. When the charging voltage of the battery 110 increases, for example, to about 4.3V, the analog front end 131 can be converted into a full charging mode, and the charging switch device 121 can be turned off. Therefore, stopping the charging of the battery 110 may require only the discharge switching device 122 to be turned on.

[0079] As described above, in order to charge the battery 110 more stably, the battery pack 100 according to an exemplary embodiment may include a structure capable of continuously adjusting the limit value of the charging current with respect to the external temperature. Further, the limit value of the charging current can be changed and set according to the temperature of the battery 110, and the battery pack 100 can be charged with the correctly maintained charging efficiency of the battery 110, thereby ensuring stability. In addition, the pre-charging operation in which the battery pack 100 provides a low initial charging current during the initial connection of the charger can prevent or sufficiently minimize the deterioration of the battery 110, thereby ensuring even

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Better stability. The battery pack 100 can charge/discharge the battery 110 according to the mode of the analog front end 131, for example, according to the overdischarge mode, the full discharge mode, the full charge mode, and the overcharge mode, in which the voltage detector 131a and the power driving circuit 131b can be embedded, thereby Guarantee even better stability.

[0080] FIG. 4 shows a flowchart of a charging method for a battery pack according to an embodiment. FIG. 5 shows the detailed flowchart of FIG. 4.

[0081] As shown in FIGS. 4 and 5, a charging method for a battery pack according to an exemplary embodiment may include: step S10: detecting temperature and current; step S20: comparing temperature and current; and step S30: adjusting charging Current. The charging method may further include step S25: determining the hysteresis zone; step S26: calculating the power consumption of the switching device; and step S27: reducing the charging current, as will be described in more detail with reference to FIG. 5 below.

[0082] Hereinafter, an exemplary charging method according to an embodiment will be described with reference to the battery pack 100 according to the flowcharts of FIGS. 4-5, that is, the battery pack having the structure described above with reference to FIGS. 1-3.

[0083] In step S10, the MPU 132 may detect the temperature and current of the battery 110 through the temperature sensor 150 and the current detection device 160, as described above with reference to FIGS. 1-3.

[0084] In step S20, the MPU 132 may compare the temperature and current detected in step S10 with the corresponding reference values in the look-up table of FIG. 2. As described above with reference to FIG. 1, the temperature-current table, that is, the look-up table in FIG. 2, can be embedded in the MPU 32, and the charging current in the battery 110 can be based on the detected temperature of the battery 110 according to the limit in the look-up table. The value 133a is adjusted.

[0085] In step S30, when the temperature and current detected by the MPU 132 are determined to exceed the limit value 133a of the charging current in the temperature-current meter in step S20, the charging current in the battery 110 can be reduced, that is, adjusted So that the charging current of the charging FET 121a does not exceed the limit value 133a of the charging current of the look-up table. In this case, the charging current of the charging FET 121a can be adjusted by controlling the duty ratio of the aforementioned PWM signal.

[0086] As described above, the charging method for a battery pack according to an exemplary embodiment can prevent the charging current of the battery pack 100 from exceeding the limit value 133a of the charging current through steps S10, S20, and S30, thereby improving the stability of the battery pack 100 .

[0087] As shown in FIG. 5, the charging method further includes steps S24 to S27. Specifically, in step S24, if the charging current of the battery 110 detected in the comparison in step S20 is lower than the limit value 133a in the look-up table determined for the detected temperature, the charging current can remain unchanged . If the current of the battery 110 detected in the comparison in step S20 is equal to or higher than the corresponding limit value in the look-up table determined for the detected temperature, the method may continue to step S25.

[0088] As shown in FIG. 5, step S25 can determine in the temperature-ampere meter whether the detected current of the battery 110 is above the hysteresis zone with positive deviation and negative deviation. Specifically, as shown in FIG. 3, the hysteresis zone 133b may be adjacent to the curve 133a, that is, a curve representing the limit of the charging current with respect to temperature is generated for correction during the temperature and current detection period of the temperature sensor 150 and the current detection device 160 The resulting measurement error. Therefore, referring to the limit value 133a of the charging current, the hysteresis region 133b can be divided into regions having a positive deviation and a negative deviation.

[0089] Therefore, if the current detected in step S20 is greater than the corresponding value in the look-up table with respect to the detected temperature, the current detected in step S25 can be evaluated with reference to the corresponding hysteresis zone. If the detected current of the battery 110 is lower than the maximum limit of the hysteresis zone 133b shown in FIG. 3, that is, within the hysteresis zone 133b, the charging current can remain unchanged and step S26 is continued. If the detected current of the battery 110 is greater than the maximum limit of the hysteresis zone 133b shown in FIG. 3, that is, outside the hysteresis zone 133b, the charging current can be reduced in step S27.

[0090] In step S27, if the current of the battery 110 is within or above the hysteresis zone, the charging current can be reduced to the hysteresis.

CN 101599552 Β

Below the rear area in order to improve the stability of the battery pack.

[0091] In step S26, the power consumption may be calculated and compared with the rated power. Specifically, step S26 may determine whether the power consumption of the charging switch device 121 is equal to or higher than the set limit power value, that is, the rated power, by calculating the power consumption of the charging switch device 121. In this case, the calculated power consumption of the charging switch device 121 may be set in consideration of the charging voltage of the charger, the open circuit voltage of the battery 110, and the charging current. More specifically, the calculated power consumption of the charging switch device 121 can be obtained by multiplying the voltage difference and the charging current, where the voltage difference is obtained by subtracting the open circuit voltage from the charging voltage.

[0092] In step S26, if the power consumption of the charging switching device 121 is equal to or higher than the set limit power value, the charging current of the charging switching device 121 may be reduced. For example, when the MPU 132 sets the limited power value to about 500W, the calculated power consumption consumed by the charging switch device 121 can be calculated using the charging voltage of the charger, the open circuit voltage and the charging current of the battery 110 as parameters. When the calculated power consumption consumed by the charging switch device 121 is equal to or higher than the limit power setting value, that is, 500W, the charging current flowing through the charging switch device 121 in step S27 can be reduced to or lower than a certain threshold, In order to ensure the stability of the battery pack 100.

[0093] Steps S25 and S26 may be executed sequentially by determining the priority. In addition, only one of steps S25 and S26 may be executed separately. In step S28, the detected charging current can be evaluated to determine whether the charging current is less than the limit of the charging current.

[0094] According to the battery pack and the charging method of the exemplary embodiment, the charging current provided by the charger can be automatically adjusted, so that stability can be ensured.

[0095] Exemplary embodiments of the present invention have been disclosed herein, and although specific terms are used, they are only used and explained in a general and descriptive sense, not for the purpose of limitation. Therefore, those of ordinary skill in the art will understand that changes can be made in form and details as long as they do not violate the spirit and scope of the present invention as set forth in the following claims.

CN 101599552 Β