Noise reduction circuit and battery management device including the same

Abstract

A noise reduction circuit according to an embodiment of the present invention includes a first circuit including one or more resistive elements and a first capacitor and connected to an ADC calculation device (Analog-Digital Converter); and a second circuit connected in parallel with the first capacitor and connected to the ADC calculation device via one or more input / output pins, and the second circuit is activated or deactivated under the control of the ADC calculation device, so that a noise cutoff frequency generated by the first circuit and the second circuit can be adjusted.

Description

[Technical Field]

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2021-0137090, filed with the Korean Intellectual Property Office on October 15, 2021, and all of the contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a noise reduction circuit and a battery management device including the same, and more particularly to a noise reduction circuit that provides a variable cutoff frequency through control of the capacitance of a capacitor of an RC filter, and a battery management device including the same. [Background technology]

[0003] Secondary batteries, which can be recharged and reused after use, are manufactured as battery modules or battery packs consisting of a number of battery cells connected in series according to the output capacity required by the device, and are used as power sources for various devices. Such batteries are used in a variety of fields, including not only small, cutting-edge electronic devices such as smartphones, but also electric bicycles, electric vehicles, and energy storage systems (ESS).

[0004] A battery module or a battery pack is a structure in which a number of battery cells are combined, and if some battery cells experience overvoltage, overcurrent, overheating, etc., this can cause problems in the safety and operating efficiency of the battery module or battery pack, so a means for detecting these is essential. For this reason, a battery module or a battery pack is equipped with a BMS (Battery Management System) that measures the voltage value of each battery cell and monitors and controls the voltage status of the battery cells based on the measured value.

[0005] In order to detect the state of the battery cells and determine if there are any abnormalities, an ADC (Analog-Digital Converter) is required to convert the analog values ​​measured through monitoring into digital values. However, the frequencies that need to be blocked vary depending on the environment in which the device is installed, and when designing taking into account frequency noise in various installation environments, the accuracy of ADC calculations can decrease, and an appropriate solution is needed. Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to provide a noise reduction circuit.

[0007] Another object of the present invention to solve the above problems is to provide a battery management device including the above noise reduction circuit. [Means for solving the problem]

[0008] To achieve the above object, one embodiment of the present invention provides a noise reduction circuit including a first circuit including one or more resistor elements and a first capacitor and connected to an ADC (Analog-Digital Converter) calculation device; and a second circuit connected in parallel with the first capacitor and connected to the ADC calculation device via one or more input / output pins, wherein the second circuit is activated or deactivated under the control of the ADC calculation device, and the noise cutoff frequency generated by the first circuit and the second circuit can be adjusted.

[0009] The second circuit includes a second capacitor connected in parallel with the first capacitor; and a switch located between the second capacitor and ground, and the second capacitor and the switch can be connected to the ADC calculation device via the one or more input / output pins.

[0010] The one or more input / output pins may include a first GPIO connecting the ADC calculation unit and the second capacitor; and a second GPIO connecting the ADC calculation unit and the switch.

[0011] The first noise cutoff frequency generated by the first circuit is different from the second noise cutoff frequency generated by the first circuit and the second circuit.

[0012] A first resistor element of the one or more resistor elements of the first circuit and the first capacitor can be connected to the ADC calculation unit via the first GPIO.

[0013] The switch may be a FET (Field Effect Transistor) element or a BJT (Bipolar Junction Transistor) element.

[0014] In order to achieve the above-mentioned another object, a battery management device according to one embodiment of the present invention includes an ADC calculation device (Analog-Digital Converter) including one or more input / output pins; a first circuit including one or more resistive elements and a first capacitor; and a second circuit connected in parallel with the first capacitor and connected to the ADC calculation device via the one or more input / output pins, wherein the second circuit includes a noise reduction circuit that is activated or deactivated under the control of the ADC calculation device, thereby adjusting the noise cutoff frequency generated by the first circuit and the second circuit.

[0015] The ADC calculation unit may further include a control unit that determines a cutoff frequency according to frequency noise in an environment where the battery management unit is located, and determines whether to activate the second circuit according to the determined cutoff frequency.

[0016] The control unit transmits an activation signal or a deactivation signal for the second circuit to a switch of the second circuit via the second GPIO.

[0017] The second circuit includes a second capacitor connected in parallel with the first capacitor; and a switch located between the second capacitor and ground, and the second capacitor and the switch can be connected to the ADC calculation device via the one or more input / output pins.

[0018] The one or more input / output pins may include a first GPIO connecting the ADC calculation unit and the second capacitor; and a second GPIO connecting the ADC calculation unit and the switch.

[0019] The ADC calculation device can be included in an MCU (Micro Controller Unit) or a BMIC (Battery Monitoring Integrated Chip). [Effects of the Invention]

[0020] According to the above-described embodiment of the present invention, the cutoff frequency of the RC filter can be variably controlled depending on the environment in which ADC performance needs to be ensured or low-frequency noise needs to be reduced.

[0021] As a result, improved performance and convenience can be expected in the BMS that performs ADC. [Brief explanation of the drawings]

[0022] [Figure 1] 1 shows the structure of a battery system to which the present invention can be applied. [Figure 2] 1 shows a noise reduction circuit applied to a conventional ADC. [Figure 3] 1 shows a noise reduction circuit and a battery management device according to an embodiment of the present invention. [Figure 4a] and [Figure 4b] 10 is a graph showing an example of ADC sensing data values ​​that have been noise reduced using an RC filter. DETAILED DESCRIPTION OF THE INVENTION

[0023] Since the present invention can be modified in various ways and can have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, it is understood that this is not intended to limit the present invention to the specific embodiments, but rather to include all modifications, equivalents, and alternatives within the spirit and technical scope of the present invention. Like reference numerals are used to refer to like elements throughout the drawings.

[0024] Terms such as "first," "second," "A," and "B" may be used to describe various components, but the components should not be limited by these terms. These terms are used only to distinguish one component from another. For example, a first component may be termed a "second component," and similarly, a second component may be termed a "first component," without departing from the scope of the present invention. The term "and / or" includes a combination of multiple associated listed items or any of multiple associated listed items.

[0025] When a component is said to be "coupled" or "connected" to another component, it is understood that the component may be directly coupled or connected to the other component, but that there may be other components in between. In contrast, when a component is said to be "directly coupled" or "directly connected" to another component, it is understood that there are no other components in between.

[0026] The terms used in this application are merely used to describe specific embodiments and are not intended to limit the present invention. The singular expressions include the plural expressions unless the context clearly indicates otherwise. It should be understood that in this application, the terms "comprise" or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and do not preclude the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0027] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which this invention pertains. Terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning they have in the context of the relevant art, and should not be interpreted as having an ideal or overly formal meaning unless expressly defined in this application.

[0028] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0029] FIG. 1 shows the structure of a battery system to which the present invention can be applied.

[0030] 1, a battery pack or a battery module may be configured to include a plurality of battery cells connected in series. The battery cell or module may be connected to a load via a positive terminal and a negative terminal to perform charge / discharge operations.

[0031] Such a battery module or battery pack may be provided with a Battery Management System (BMS) 100. The BMS monitors the current, voltage, and temperature of each battery pack under its management, calculates the SOC (Status of Charge) based on the monitoring results, and controls charging and discharging. Here, the SOC (State of Charge) is the current charged state of the battery expressed as a percentage [%], and the SOH (State of Health) is the current deterioration state of the battery expressed as a percentage [%].

[0032] To perform these operations, the BMS may include various components such as fuses, current sensing elements, thermistors, switches, and balancers, but in most cases, it also includes an MCU (Micro Controller Unit) or BMIC (Battery Monitoring Integrated Chip) to interface with and control these components. Here, the BMIC may be an IC-type component located inside the BMS that measures information such as the voltage, temperature, and current of the battery cell / module.

[0033] Meanwhile, in order for the BMS to detect the state of the battery cells and determine abnormalities, an ADC (Analog-Digital Converter) operation is required to convert the analog values ​​measured through monitoring into digital values.

[0034] Conventionally, ADC calculations are performed through an MCU or BMIC, which performs ADC conversion on voltage, current, temperature, etc. input via the GPIO (general-purpose input / output) pins of these devices. In this case, an RC filter is used to reduce frequency noise in the voltage or temperature signal input via the GPIO (general-purpose input / output) pin.

[0035] FIG. 2 shows a noise reduction circuit applied to a conventional ADC.

[0036] Referring to Fig. 2, the BMS 10 may include an ADC calculation unit 11. The ADC calculation unit 11 may be a BMIC or an MCU and may include multiple GPIO pins. In the example of Fig. 2, the GPIO 01 pin is shown as being used for ADC calculation. The ADC calculation unit converts analog measurement signals such as output cell voltages and resistance values ​​into digital values.

[0037] In the example of Figure 2, a thermistor R2 is used as the monitoring target for the battery cell, and a noise reduction circuit including a resistor and a capacitor is placed between the monitoring target element R2 and GPIO pin 01 of the ADC calculation unit 11.

[0038] 2 includes a capacitor C1 and one or more resistors R3. More specifically, the noise reduction circuit may include R1, one side of which is connected to a power supply Vcc and the other side of which is connected to one side of R2 (a PTC or NTC element), R3, one side of which is connected to the junction of R1 and R2 and the other side of which is connected to the junction between C1 and the GPIO pin, and C1, which is connected to the GPIO pin and ground.

[0039] Here, the thermistor may be a PTC (Positive Temperature Coefficient) thermistor or an NTC (Negative Temperature Coefficient) thermistor.

[0040] PTC is a semiconductor element that has the characteristic that its resistance value changes with temperature, increasing as the temperature rises and decreasing as the temperature drops. NTC also has the characteristic that its resistance value changes with temperature, but in contrast to PTC, its resistance value decreases as the temperature rises and increases as the temperature drops.

[0041] In a conventional noise reduction circuit, a cutoff frequency is determined using an RC circuit including C1 and R3. The cutoff frequency can be determined by the following Equation 1:

[0042]

number

[0043] In Equation 1, F cutoff indicates the cutoff frequency, R3 indicates the resistance value of the resistor element R3, and C1 indicates the capacitance value of the capacitor C1.

[0044] In such a circuit, once the capacitor and resistor elements selected with predetermined capacitance and resistance values ​​are mounted on the device, the capacitance of the capacitor cannot be changed. However, if the installation environment changes, the target noise to be reduced also changes, but since the cutoff frequency of the conventional RC circuit cannot be changed, the desired noise reduction cannot be achieved.

[0045] When applying an ADC to a BMS, the resistance value and capacitance of the RC filter are selected taking into consideration the overall noise environment of the product and the accuracy of the ADC. However, the range of frequencies that must be blocked varies depending on the installation environment, and if the design takes into consideration the frequency noise of all installation environments, the accuracy of the ADC will decrease, making the design difficult.

[0046] FIG. 3 shows a noise reduction circuit and a battery management device according to an embodiment of the present invention.

[0047] The noise reduction circuit according to the present invention shown in FIG. 3 may include a first circuit 210 including one or more resistor elements R3 and a first capacitor C1 and connected to the ADC calculation device 300, and a second circuit 220 connected in parallel with the first capacitor C1 and connected to the ADC calculation device via one or more input / output pins.

[0048] The first circuit can be configured to include one capacitor C1 and one or more resistors R3, similar to a conventional noise elimination circuit.

[0049] The second circuit includes a second capacitor C2 connected in parallel with the first capacitor C1; and a switch Q1 located between the second capacitor and ground, and the second capacitor and the switch can be connected to the ADC calculation device 300 via one or more input / output pins.

[0050] Here, the switch Q1 can be realized as a FET (Field Effect Transistor) element or a BJT (Bipolar Junction Transistor) element.

[0051] Furthermore, the battery management device 1000 according to the present invention includes an ADC calculation device (Analog-Digital Converter) including one or more input / output pins; a first circuit 210 including one or more resistive elements and a first capacitor; and a second circuit 220 connected in parallel with the first capacitor and connected to the ADC calculation device via one or more input / output pins, and the second circuit may include a noise reduction circuit that is activated or deactivated by the control of the ADC calculation device, thereby adjusting the noise cutoff frequency generated by the first circuit and the second circuit.

[0052] Here, the one or more input / output pins may include a first GPIO connecting the ADC calculation unit and the second capacitor, and a second GPIO connecting the ADC calculation unit and the switch.

[0053] 3, a control unit 310 in the ADC calculation unit may determine a cutoff frequency according to frequency noise in an environment where the battery management unit is located, and may determine whether to activate a second circuit according to the determined cutoff frequency. In FIG. 3, the ADC calculation unit may be an MCU (Micro Controller Unit) or a BMIC (Battery Monitoring Integrated Chip), or may be implemented as being included in these components.

[0054] Here, the control unit can transmit an activation or deactivation signal for the second circuit to the switch Q1 of the second circuit via the second GPIO. When the switch receives the activation signal, it is turned on, connecting the second capacitor C2 to the first GPIO and ground, resulting in a configuration in which the first capacitor and the second capacitor are connected in parallel. On the other hand, when the switch receives a deactivation signal for the second circuit, it is turned off, opening the second capacitor, and only the signal of the first circuit, consisting of the first capacitor and the resistor, is input to the first GPIO.

[0055] When the control unit 310 deactivates the second circuit, the cutoff frequency is determined by the first circuit, and the cutoff frequency at this time can be determined as defined in Equation 1 above.

[0056] In contrast, when the control unit 310 activates the second circuit, the first capacitor C1 of the first circuit and the second capacitor C2 of the second circuit are arranged in parallel, and in this case, the total capacitor capacitance can be expressed as (C1+C2).

[0057] Therefore, the cutoff frequency generated by the first circuit and the second circuit can be determined by the following Equation 2.

[0058]

number

[0059] In Equation 2, F cutoff indicates the cutoff frequency, R3 indicates the resistance value of the resistor element R3, C1 indicates the capacitance value of the capacitor C1, and C2 indicates the capacitance value of the capacitor C2.

[0060] That is, the cutoff frequencies provided by the first circuit and the second circuit according to the embodiment of the present invention can be controlled to either the first cutoff frequency (Equation 1) or the second cutoff frequency (Equation 2). In other words, the first noise cutoff frequency and the second noise cutoff frequency are set to different values.

[0061] 3, the example in which the thermistor R2 is monitored is described, but the element to be monitored by the BMS may be a voltage sensor, a current sensor, etc. In this case, the analog signal detected by the element may be a voltage value or a current value.

[0062] 4a and 4b are graphs showing examples of ADC sensing data values ​​that have been noise reduced using an RC filter.

[0063] The data sensed in the examples of Figures 4a and 4b is the module voltage, with the horizontal axis of the graph representing time (t) and the vertical axis representing module voltage (mV). In the example of Figure 4a, a capacitor with a capacitance of 47 nF was used in the RC filter, and in the example of Figure 4b, a capacitor with a capacitance of 1 nF was used.

[0064] Graphs 4a and 4b show that the ADC performance changes depending on the RC filter capacitor capacitance for the same circuit. That is, when a 47nF capacitor is used, the calculated module voltage variation (difference between maximum and minimum values) is 4mV, but when a 1nF capacitor is used, the calculated module voltage variation is 0.5mV. In other words, the example in Figure 4b is superior in terms of ADC performance.

[0065] In contrast, when a 1nF capacitor is used, the cutoff frequency is 47 times higher than when a 47nF capacitor is used, which makes it difficult to block low-frequency noise.

[0066] Therefore, the example of FIG. 4a, which uses a relatively high capacitance capacitor, is advantageous for blocking low frequency noise, while the example of FIG. 4b, which uses a relatively low capacitance capacitor, is advantageous for ADC performance.

[0067] In short, depending on the installation environment and end user requirements, the capacitor capacitance can be varied so that a filter with a relatively low capacitance is applied when it is necessary to ensure ADC performance, and a filter with a relatively high capacitance is applied when there is a particular need to further reduce low-frequency noise.

[0068] By applying such data to the above-described embodiment of the present invention, it is possible to embody a configuration in which a first circuit with a capacitor capacitance of C1 is applied in an environment where ADC performance must be ensured, and a first circuit and a second circuit with capacitor capacitances of (C1+C2) are used in an environment where low-frequency noise must be reduced. In other words, by embodying an RC filter circuit, the second circuit is deactivated when ADC performance must be ensured, and the second circuit is activated when low-frequency noise must be reduced, the cutoff frequency can be variably controlled.

[0069] The operations of the methods according to the embodiments of the present invention can be embodied as a computer-readable program or code on a computer-readable recording medium. The computer-readable recording medium includes all kinds of storage devices in which data that can be read by a computer system is stored. In addition, the computer-readable recording medium can be distributed among computer systems connected via a network, so that the computer-readable program or code can be stored and executed in a distributed manner.

[0070] Some aspects of the invention have been described in the context of an apparatus, but they may also be described in terms of a corresponding method, where a block or apparatus corresponds to a method step or feature of a method step. Similarly, aspects described in the context of a method may be described in terms of a corresponding block or item or feature of a corresponding apparatus. Some or all of the method steps may be performed by (or using) a hardware apparatus, such as a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most important method steps may be performed by such an apparatus.

[0071] Although the present invention has been described above with reference to preferred embodiments, those skilled in the art will understand that various modifications and variations of the present invention can be made without departing from the spirit and scope of the present invention as set forth in the following claims. [Explanation of symbols]

[0072] 10 BMS 11 ADC calculation section 300 ADC calculation unit 310 Control Unit 1000 battery management device

Claims

1. A battery management device, an ADC computing device (Analog-Digital Converter) including a first pin and a second pin; and a first circuit including one or more resistor elements and a first capacitor, the first circuit being connected to the ADC calculation unit via the first pin; and a second capacitor connected in parallel with the first capacitor and connected to the ADC calculation unit via the first pin; a switch located between the second capacitor and ground and connected to the ADC calculation unit via a second pin; a second circuit; the second circuit includes a noise reduction circuit that is activated or deactivated under the control of the ADC calculation device according to frequency noise in an environment where the battery management device is located, thereby adjusting a noise cutoff frequency generated by the first circuit and the second circuit; The ADC calculation device includes a control unit that determines a cutoff frequency based on frequency noise in the environment and determines whether to activate the second circuit in accordance with the determined cutoff frequency.

2. the first pin is a first GPIO that connects the ADC calculation unit and the second capacitor; The battery management device according to claim 1 , wherein the second pin is a second GPIO that connects the ADC calculation device and the switch.

3. The control unit The battery management device according to claim 1 , wherein an activation signal or a deactivation signal for the second circuit is transmitted to the switch via a second GPIO.

4. The battery management device according to claim 1 , wherein the ADC calculation device is included in an MCU (Micro Controller Unit) or a BMIC (Battery Monitoring Integrated Chip).

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