Fault detection device

Abstract

A fault detection device according to an embodiment of the present invention comprises: a plurality of resistors connected in series between two input terminals of a converter; a sensing circuit that measures a first voltage at one of the nodes between the plurality of resistors; and a processor that detects a fault by using a change in the first voltage.

Description

Technical Field

[0001] The present invention relates to a fault detection device, and more particularly to a fault detection device, a converter, and a battery pack capable of detecting a contact fault. Background Art

[0002] With the increase in environmental protection awareness in recent years, the interest in power generation methods that do not emit pollutants such as carbon dioxide has grown. In particular, in the case of a photovoltaic system using solar energy, due to technological progress, the cost of developing and installing the technology has become cheaper, and their spread is expanding.

[0003] A photovoltaic system is composed of a plurality of photovoltaic cells that are aggregated together to form a plurality of photovoltaic modules. The DC power generated from the plurality of photovoltaic modules can be converted into AC power by an inverter and can be directly used in homes and industrial facilities.

[0004] In the case of solar power generation, when power generation is insufficient due to a night time period without sunlight or weather changes, an inactive period in power generation is inevitable. Therefore, in order to compensate for these disadvantages, a photovoltaic system must basically be provided with a battery to ensure a stable supply of power.

[0005] A household photovoltaic system including a battery can be configured as shown in Figure 1 The inside of the battery pack may be composed of a battery, a BMS, and a DC-DC converter. Here, when there is any problem in the battery pack such that the battery provided in the battery pack and the battery pack housing come into contact with each other, the entire system may have problems, and thus a technique for detecting a fault is required. Summary of the Invention

[0006] Technical Problem

[0007] The technical problem to be solved by the present invention is to provide a fault detection device, a converter, and a battery pack capable of detecting a contact fault.

[0008] Technical Solution

[0009] To solve the above technical problem, a fault detection device according to an embodiment of the present invention includes: a plurality of resistors connected in series between both ends of an input terminal of a converter; a sensing circuit configured to measure a first voltage at one of nodes between the plurality of resistors; and a processor configured to detect a fault by using a change in the first voltage.

[0010] Additionally, multiple resistors may include a first resistor, a second resistor, and a third resistor, which are sequentially connected in series from the positive terminal of the input terminal to the negative terminal of the input terminal. Among them, the node between the first resistor and the second resistor may be connected to the housing of the converter, and the sensing circuit may be configured to measure a first voltage at the node between the second resistor and the third resistor.

[0011] Additionally, the sensing circuit may include an inverting amplifier and a non-inverting amplifier. Among them, the outputs of the inverting amplifier and the non-inverting amplifier may be applied to the processor.

[0012] Additionally, the fault detection device may further include: a first low-pass filter configured to filter the output of the non-inverting amplifier; and a second low-pass filter configured to filter the output of the inverting amplifier. Among them, the outputs of the inverting amplifier and the non-inverting amplifier may be applied to the processor through the first low-pass filter and the second low-pass filter, respectively.

[0013] Additionally, the processor may be configured to detect a fault by using the difference between the output of the inverting amplifier and the output of the non-inverting amplifier.

[0014] Additionally, the output terminal of the converter may be connected to the power grid, and the processor may be configured to: filter the difference between the output of the inverting amplifier and the output of the non-inverting amplifier by using a band-pass filter configured to filter the frequency band of the power grid; and compare the amplitude level of the filtered difference between the output of the inverting amplifier and the output of the non-inverting amplifier with a reference level and detect a fault.

[0015] Additionally, the processor may be configured to: determine that a fault has occurred when the amplitude level of the difference between the output of the inverting amplifier and the output of the non-inverting amplifier is less than the reference level for a predetermined period of time.

[0016] Additionally, when a fault is detected, the processor may be configured to block the connection of at least one of the input terminal or the output terminal of the converter.

[0017] Additionally, the converter may include a DC-DC converter inside the battery pack, and the processor may be configured to detect a contact or ground fault of the battery in the battery pack.

[0018] Additionally, the converter may include a DC-DC converter connected to the photovoltaic module, and the processor may be configured to detect a contact or ground fault of at least one of the two ends of the input terminal of the photovoltaic module.

[0019] To solve the above technical problems, a DC-DC converter according to an embodiment of the present invention includes: an input terminal connected to a battery or a photovoltaic panel; and a fault detection circuit configured to detect a contact or grounding fault of at least one of the two ends of the input terminal, wherein the fault detection circuit includes one of the above-mentioned fault detection devices.

[0020] To solve the above technical problems, a battery pack according to an embodiment of the present invention includes: a battery; a DC-DC converter configured to convert the voltage of the battery; and a fault detection circuit configured to detect a contact or grounding fault of the battery, wherein the fault detection circuit includes one of the above-mentioned fault detection devices, and when a contact or grounding fault of the battery is detected, the fault detection circuit is configured to block the connection to the outside.

[0021] Advantageous Effects

[0022] According to an embodiment of the present invention, a contact (insulation breakdown) fault in a battery power source of a power conversion system for solar energy and grid-connected ESS can be detected. Description of the Drawings

[0023] Figure 1 FIG. is a diagram for explaining a photovoltaic system to which a fault detection device according to an embodiment of the present invention is applied.

[0024] Figure 2 FIG. is a block diagram of a fault detection device according to an embodiment of the present invention.

[0025] Figure 3 FIG. is a block diagram of a fault detection device according to an embodiment of the present invention.

[0026] Figures 4 to 7 FIG. is a diagram for explaining a fault detection device according to an embodiment of the present invention.

[0027] Figure 8 and Figure 9 FIG. is a diagram showing an application example of a fault detection device according to an embodiment of the present invention.

[0028] Figure 10 FIG. is a block diagram of a DC-DC converter according to an embodiment of the present invention.

[0029] Figure 11 FIG. is a block diagram of a battery pack according to an embodiment of the present invention.

[0030] Figure 12 FIG. is a flowchart of a fault detection method according to an embodiment of the present invention.

[0031] Figure 13It is a flowchart of a fault detection method according to an embodiment of the present invention. Detailed Embodiments

[0032] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0033] However, the technical idea of the present invention is not limited to some of the described embodiments, but can be implemented in various different forms, and even one or more components in the embodiments can be selectively combined or replaced within the scope of the technical idea of the present invention for use.

[0034] In addition, unless clearly and specifically defined and described, the terms (including technical terms and scientific terms) used in the embodiments of the present invention can be interpreted as having the meanings commonly understood by those of ordinary skill in the technical field to which the present invention pertains, and the terms commonly used, such as the terms defined in a dictionary, can be interpreted in consideration of the context meaning of the related technology.

[0035] In addition, the terms used in the embodiments of the present invention are for the purpose of describing the embodiments and are not intended to limit the present invention.

[0036] In this specification, unless specifically stated otherwise in a phrase, the singular may also include the plural, and when it is described as “(at least one of) A and (or) B, C”, it may include one or more of all combinations that can be combined with A, B, C.

[0037] In addition, when describing the components of the embodiments of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only intended to distinguish one component from another component and are not intended to limit the nature, order or sequence of the components.

[0038] In addition, when a component is described as “connected”, “coupled” or “linked” to another component, it may include not only the case where the component is directly “connected”, “coupled” or “linked” to other components, but also the case where the component is “connected”, “coupled” or “linked” to other components through another component between the component and the other components.

[0039] In addition, when described as being “above (on)” or “below (under)” each component, “above (on)” or “below (under)” includes not only the case where two components are in direct contact with each other, but also the case where one or more other components are formed or arranged between the two components. In addition, when expressed as “above (on)” or “below (under)”, it includes not only the meaning of the upward direction based on one component, but also the meaning of the downward direction based on one component.

[0040] Modification examples of the present embodiment may include some configurations of some embodiments and some configurations of other embodiments. That is, a modification example may include one embodiment among various embodiments, but some components may be omitted and some components of the corresponding other embodiments may be included. Alternatively, the reverse is also possible. The features, structures, and effects described in the embodiments are incorporated into at least one embodiment, but are not limited to only one embodiment. In addition, the features, structures, and effects illustrated in one embodiment can be easily combined and modified by those skilled in the art for another embodiment. Therefore, the content related to these combinations and modifications should be interpreted as falling within the scope of the embodiments.

[0041] Figure 1 is a diagram for explaining a photovoltaic system to which a fault detection device according to an embodiment of the present invention is applied.

[0042] As Figure 1 shown, the photovoltaic system may include a photovoltaic source 10, an inverter 20, a battery pack 30, and a load 50. However, those skilled in the art will understand that, in addition to Figure 1 the components shown in Figure 1 there may also be other general components in the photovoltaic system. For example, the photovoltaic system may also include a power grid 40. Alternatively, those skilled in the art will understand that in other embodiments, some of the components shown in Figure 1 may be omitted.

[0043] The photovoltaic source 10 may be composed of a plurality of photovoltaic modules. Photovoltaic cells are aggregated in the photovoltaic modules, and each photovoltaic cell in which a P-type semiconductor and an N-type semiconductor are combined with each other generates electricity using light. Specifically, when light irradiates the photovoltaic cell, electrons and holes are generated in the photovoltaic cell. The generated charges move to each of the P pole and the N pole, and this action generates a potential difference between the P pole and the N pole, and when a load is connected to the photovoltaic cell, an electric current flows. Here, the photovoltaic cell means the smallest unit that generates electricity, and the photovoltaic cells can be aggregated to form a cell module, and the cell modules can form an array connected in series / parallel again to form the photovoltaic source 10.

[0044] The inverter 20 can convert the DC (direct current) power generated from the photovoltaic source 10 through the photovoltaic effect into AC (alternating current) power to supply power to the power grid 40 or the load 50. Here, the power grid 40 may refer to a system (power grid) for transmitting and distributing the power generated from the photovoltaic system. The amount of power generated from the photovoltaic source 10 continuously varies due to time factors such as sunrise and sunset and external factors such as weather. Therefore, the inverter 20 controls the voltage generated from the photovoltaic source 10 to find the maximum power, so as to supply the maximum power to the power grid 40. Here, when the power used to drive the inverter is lower than the output power of the inverter, the inverter 20 can consume power from the power grid 40 in reverse. Of course, in this case, the inverter can block the power from flowing into the power grid 40 to prevent the power from being reversed. Therefore, various optimization control methods are applied to the photovoltaic system to enable the above operation of the inverter 20 to be performed more effectively, so as to extract the maximum power from the photovoltaic source 10. The maximum power point (MPP) methods for the representative photovoltaic source 10 include the perturbation and observation (PO) method, the incremental conductance (IC) control method, and the constant voltage (CV) control method. Here, the PO method is a method for periodically measuring the voltage and current of the photovoltaic source 10 to calculate the power, and then using the power value to track the MPP. The IC control method is a method for measuring the voltage and current generated from the photovoltaic source 10 to control the voltage and current so that the power change rate with respect to the change of the operating point of the terminal voltage of the array becomes "0". The CV control method is a method for controlling the photovoltaic source 10 to a constant reference voltage (REF V) without considering the operating voltage or power of the array. Depending on each optimization control method, the power source input from the photovoltaic source 10 to the inverter can operate as a voltage source or a current source.

[0045] The load 50 may refer to products that use electricity in the form used in real life. For example, the inverter 20 can obtain AC power with a desired voltage and frequency through an appropriate conversion method, switching element, or control circuit to supply electricity to household appliances in general household appliances or mechanical products in industrial facilities. In addition, in the case of solar power generation, when power generation cannot be sufficient due to nighttime periods without sunlight or weather changes, inactive periods in power generation are inevitable. Therefore, to compensate for these drawbacks, the photovoltaic system must basically be provided with a battery to ensure a stable supply of power.

[0046] The battery pack 30 may include at least one of a DC-DC converter, a battery, a battery management system (BMS), and a battery control circuit. The battery may be composed of a lithium-ion battery or a nickel-metal hydride battery, but is not necessarily limited to this configuration, and may refer to a battery that can be used semi-permanently through charging. The DC-DC converter may be a device that converts the DC power generated by the photovoltaic source 10 into DC power suitable for the battery or converts the battery power into power suitable for the power grid. Generally, power can be converted by converting DC power into AC power and then converting the AC power back into DC power. The battery management system (BMS) may provide functions such as protection of battery cells constituting the battery, balancing between individual battery cells, state of charge (SOC), temperature maintenance, or system monitoring. Therefore, based on sensors that measure the state of the battery cells and a function that receives the measurement values of the sensors to send the measurement values to the control system of the application product, a circuit can be constructed and controlled to generate an abnormal signal and block or disconnect the power circuit between the battery cells when the temperature and state of charge of the system exceed the set values.

[0047] Figure 2 is a block diagram of a fault detection device according to an embodiment of the present invention. Figure 3 is a block diagram of a fault detection device according to an embodiment of the present invention, Figures 4 to 7 is a diagram for explaining a fault detection device according to an embodiment of the present invention, and Figure 8 and Figure 9 is a diagram showing an application example in which a fault detection device according to an embodiment of the present invention is applied.

[0048] The fault detection device 100 according to an embodiment of the present invention detects faults caused by contact or ground faults. Contact means that even though the input / output terminals and the housing should be insulated from each other, contact occurs between the input / output terminals and the housing (outer casing) and an electrical connection is made. Due to insulation breakdown, etc., ground faults, etc. may occur. A ground fault means that the grounding state is abnormal, and due to external shocks, etc., the grounding terminal comes into contact with a position other than the normal position. If a ground or contact fault occurs, damage may occur inside the device or other connected devices when connected to the battery or power device, and overcurrent may occur, leading to a risk of fire or explosion. To prevent this phenomenon, it is necessary to quickly detect the occurrence of faults such as contact or ground faults.

[0049] To detect faults such as contact or ground faults, the fault detection device 100 according to an embodiment of the present invention is composed of a plurality of resistors 110, a sensing circuit 120, and a processor 130.

[0050] A plurality of resistors 110 are connected in series between the input terminals 210 of the converter. A sensing circuit 120 measures a first voltage at one of the nodes between the plurality of resistors 110, and a processor 130 uses a change in the first voltage to detect a fault.

[0051] The input terminals 210 may be connection terminals of the converter. Although referred to as input terminals, they may also be input / output terminals for inputting or outputting power. The input terminals 210 may include two terminals such as a positive terminal and a negative terminal. Here, the converter may be a converter used in a photovoltaic system, a DC-DC converter included in a battery pack of a photovoltaic system, or a DC-DC converter connected to a photovoltaic panel. Additionally, it is obvious that it may be applied to converters of various devices for inputting and outputting power.

[0052] The plurality of resistors 110 may include a first resistor 111, a second resistor 112, and a third resistor 113. The first resistor 111, the second resistor 112, and the third resistor 113 are sequentially connected in series from the positive terminal of the input terminal 210 to the negative terminal of the input terminal 210. The node between the first resistor 111 and the second resistor 112 may be connected to the housing 220 of the converter, and the sensing circuit 120 may measure the first voltage at the node between the second resistor 112 and the third resistor 113. To detect whether contact occurs at either the positive terminal or the negative terminal, the first voltage is measured between the resistors connecting the positive terminal to the negative terminal. To detect a change in the first voltage due to contact with the housing 220, the terminals between the first resistor 111 and the second resistor 112 are connected to contact the housing 220. Therefore, the voltage at the node between the first resistor 111 and the second resistor 112 may be equal to the voltage of the housing 220, and the housing 220 may correspond to the lowest voltage of the device on which the converter is mounted. The first voltage is measured by sensing the voltage at the terminals between the second resistor 112 and the third resistor 113.

[0053] The sensing circuit 120 measures a first voltage, including a non-inverting amplifier 121 and an inverting amplifier 122 - each of the non-inverting amplifier 121 and the inverting amplifier 122 receives the first voltage and sends the output of the inverting amplifier 122 and the output of the non-inverting amplifier 121 to the processor 130. The input terminal 210 of the converter can be connected to a battery or a photovoltaic panel, and the output terminal of the converter can be connected to the power grid. Since the power grid uses AC voltage, it has a constant frequency instead of a triangular waveform with a constant voltage value. For example, it can have a frequency of 60 Hz in single-phase line-to-line (L-L) mode or a frequency of 50 Hz in single-phase line-to-neutral (L-N) mode. Therefore, the voltages at the two terminals of the input terminal of the converter may also be affected to cause ripples. Additionally, during normal operation, the first voltage has a predetermined offset value but fluctuates at a predetermined frequency. Here, when a contact occurs between the positive terminal or the negative terminal of the input terminal 210, the value of the first voltage can change depending on whether the positive terminal contacts the housing 220 or the negative terminal contacts the housing 220. Therefore, to detect these two cases, the first voltage is not used as it is, but instead the first voltage passes through the inverting amplifier 122 and the non-inverting amplifier 121 and then is sent to the processor 130. Here, each of the inverting amplifier 122 and the non-inverting amplifier 121 serves as a buffer, but the non-inverting amplifier 121 has the same phase and the inverting amplifier 122 has an inverted phase.

[0054] A first low-pass filter (LPF) 123 for filtering the output of the non-inverting amplifier 121 and a second low-pass filter 124 for filtering the output of the inverting amplifier 122 can be provided, and the output of the non-inverting amplifier 121 and the output of the inverting amplifier 122 can be applied to the processor 130 through the first low-pass filter 123 and the second low-pass filter respectively. The output of the non-inverting amplifier 121 and the output of the inverting amplifier 122 can contain noise. The noise can be removed by the low-pass filters to apply only the necessary signals to the processor 130.

[0055] The processor 130 can be as Figure 4The microcontroller unit (MCU) shown, and can receive signals through the analog-to-digital converter (ADC), enabling the processor 130 to utilize the corresponding values. That is, the output of the non-inverting amplifier 121 of the low-pass filter (LPF) 123 and the output of the inverting amplifier 122 of the low-pass filter (LPF) 124 can be received through ADC1 131 and ADC2 132 respectively. The processor 130 can detect a fault by using the difference between the output of the inverting amplifier and the output of the non-inverting amplifier. The output of the inverting amplifier and the output of the non-inverting amplifier have values with opposite phases to each other, and can be represented as triangular waveforms with a predetermined phase independent of the offset value and independent of the offset value of the first voltage.

[0056] The processor 130 can use a band-pass filter (BPF) that filters the frequency band of the power grid to filter the difference between the output of the inverting amplifier and the output of the non-inverting amplifier, and compare the amplitude level of the filtered difference between the output of the inverting amplifier and the output of the non-inverting amplifier with a reference level to detect a fault. The frequency of the difference between the output of the inverting amplifier and the output of the non-inverting amplifier is affected by the frequency of the power grid. After removing the offset of the first voltage through the difference between the output of the inverting amplifier and the output of the non-inverting amplifier, the difference between the output of the inverting amplifier and the output of the non-inverting amplifier is filtered using a band-pass filter (BPF) that filters the frequency band of the power grid. Therefore, noise can be removed, and only the signals required for detecting a fault can be used. Therefore, the voltage amplitude level of the filtered difference between the output of the inverting amplifier and the output of the non-inverting amplifier is calculated and compared with the reference level. In the case of a contact or ground fault, the fluctuation of the first voltage caused by the influence of the power grid is reduced according to the connection with the housing 220. That is, the voltage amplitude level of the filtered difference between the output of the inverting amplifier and the output of the non-inverting amplifier can be reduced, and thus, the processor 130 can compare the reduction of the voltage amplitude level with the reference level, and if the voltage amplitude level of the filtered difference between the output of the inverting amplifier and the output of the non-inverting amplifier is less than the reference level, it can be determined that a fault has occurred. The reference level can be determined based on design or simulation results, or can be set by the user.

[0057] When the magnitude level of the difference between the output of the filtered inverting amplifier and the output of the non-inverting amplifier is less than the reference level for a predetermined period of time, the processor 130 may determine a fault. Due to changes in the power grid or in some configurations of the entire system, the magnitude level of the difference between the output of the temporarily filtered inverting amplifier and the output of the non-inverting amplifier may be less than the reference level for a short period of time. In this case, it can be immediately determined that it is a fault and not operate in the safe mode, and in the temporary situation, the system can operate without determining that it is a fault. The fault determination time can be set to the minimum time at which no damage to the battery etc. will occur, and can be set by design or simulation, or can be set by the user.

[0058] When a fault is detected, the processor 130 may block the connection of at least one of the input terminal or the output terminal of the converter. When it is determined that a fault has occurred based on the fault determination, the connection of at least one of the input terminal or the output terminal of the converter connected to the device can be blocked to prevent damage to the device, which may be damaged due to contact. The input or output terminal of the converter may be connected to a circuit breaker. Here, the circuit breaker may include a switch and may be a circuit breaker (CB). Additionally, it may include various devices capable of blocking the connection, such as a relay.

[0059] The process of detecting contact and blocking the connection when contact is detected as shown in Figure 5 may be performed. When the CB as the circuit breaker is connected, a first voltage is sensed, the output of the inverting amplifier and the output of the non-inverting amplifier are input using the inverting amplifier and the non-inverting amplifier, and the difference between the output of the inverting amplifier and the output of the non-inverting amplifier is calculated. Here, the frequency of the power grid is determined according to the type of the power grid, and a band-pass filter for filtering the corresponding frequency band is used to filter the difference between the output of the inverting amplifier and the output of the non-inverting amplifier. Therefore, the magnitude level of the difference between the output of the filtered inverting amplifier and the output of the non-inverting amplifier (V_G_BPF magnitude calculation) is calculated, and the calculated magnitude level V_G_M is compared with the reference level V_G_LEVEL. When the magnitude level V_G_M is greater than the reference level V_G_LEVEL, it is determined that no contact or ground fault has occurred, and the system operates. When the magnitude level V_G_M is equal to or less than the reference level V_G_LEVEL for a given period of time T_S, it is determined that a contact or ground fault has occurred, and for safety, the CB is turned off.

[0060] Figure 6 is a graph showing the result of determining a fault when the fault detection device detects contact of the battery and the power grid type has a frequency of 60 Hz in the L-L mode, and Figure 7It is a graph showing the result of determining a fault when the grid type has a frequency of 50 Hz in the L-N mode. V_G as the first voltage has different values when a fault occurs depending on whether it is connected to the positive terminal or the negative terminal, but it can be confirmed that the amplitude level of the difference BPF(ADC1 - ADC2) between the output of the filtered inverting amplifier and the output of the non-inverting amplifier decreases regardless of the V_G value. That is, the difference between the output of the filtered inverting amplifier and the output of the non-inverting amplifier can be used to perform contact fault detection, and it can be confirmed that contact fault detection is possible regardless of the type of the grid or the location where the contact occurs.

[0061] The converter can be a DC-DC converter inside the battery pack, and in this case, the processor 130 can detect the contact or ground fault of the batteries in the battery pack. As Figure 8 shown, the battery pack can include batteries and a converter, and the fault detection device can detect the contact between the cases at both ends of the input terminal connected to the batteries of the DC-DC converter inside the battery pack. The output terminal of the battery pack can be connected to the grid through an inverter (PCS), and when a fault is detected, the CB connected to the battery output terminal can be disconnected to cut off the connection with the inverter and the grid. Additionally, the connection with the batteries and the DC-DC converter can be blocked.

[0062] The converter can be a DC-DC converter connected to the photovoltaic module, and at this time, the processor 130 can detect the contact or ground fault of at least one of the two ends of the input terminal of the photovoltaic module of the DC-DC converter. As Figure 9 shown, the photovoltaic system can include a converter and an inverter, and the fault detection device can detect the contact between the cases at both ends of the input terminal connected to the photovoltaic module (PV module) of the DC-DC converter inside the photovoltaic system module. The output terminal of the photovoltaic system can be connected to the grid, and when a fault is detected, the connection with the photovoltaic module can be cut off.

[0063] As described above, the first voltage can be detected through a plurality of resistors and a sensing circuit, and the first voltage can be compared with a reference level using the first voltage to detect faults such as contact or ground faults. Therefore, contact (insulation breakdown) faults in the battery power source of the power conversion system for solar energy and grid-connected ESS can be detected.

[0064] Figure 10 It is a block diagram of a DC-DC converter according to an embodiment of the present invention.

[0065] The DC-DC converter 1000 according to an embodiment of the present invention includes an input terminal 210 connected to a battery or a photovoltaic panel, and a fault detection circuit that detects contact or ground faults of at least one of the terminals across the input terminal. The detailed description of the fault detection circuit of the DC-DC converter 1000 according to an embodiment of the present invention corresponds to Figures 1 to 9 the detailed description of the fault detection device, and any repeated description will be briefly described below.

[0066] The DC-DC converter 1000 of the present invention is connected to a battery or a photovoltaic panel through the input terminal 210 to convert the input power and then output the converted power. The DC-DC converter 1000 may be a DC-DC converter included in a battery pack, and at this time, power can be received from the battery, converted, and output, and the output power can be sent to the power grid through an inverter. Alternatively, power can be received from a photovoltaic panel or the power grid and then converted to charge the battery. The DC-DC converter 1000 may be a DC-DC converter included in a photovoltaic module, and can receive the power generated from the photovoltaic panel to convert the received power and then output the converted power. The output power can be sent to the power grid through an inverter, or can be used to charge the battery.

[0067] The fault detection circuit detects contact or ground faults of at least one of the input terminals of the DC-DC converter. The fault detection circuit may include: a plurality of resistors 110 connected in series between two input terminals of the converter, a sensing circuit 120 that measures a first voltage at one of the nodes between the plurality of resistors, and a processor 130 that detects a fault by using a change in the first voltage.

[0068] Here, the plurality of resistors may include a first resistor, a second resistor, and a third resistor, which are sequentially connected in series from the positive terminal of the input terminal 210 to the negative terminal of the input terminal 210. The node between the first resistor and the second resistor may be connected to the housing of the converter 1100, and the sensing circuit 120 may measure the first voltage at the node between the second resistor and the third resistor. The sensing circuit 120 may include an inverting amplifier and a non-inverting amplifier - each of the inverting amplifier and the non-inverting amplifier receives the first voltage, and the output of each of the outputs of the inverting amplifier and the non-inverting amplifier may be applied to the processor 130.

[0069] Additionally, a first low-pass filter for filtering the output of the inverting amplifier and a second low-pass filter for filtering the output of the non-inverting amplifier can be provided, and the output of the inverting amplifier and the output of the non-inverting amplifier can be applied to the processor 130 through the first low-pass filter and the second low-pass filter respectively, and the processor 130 can detect a fault by utilizing the difference between the output of the inverting amplifier and the output of the non-inverting amplifier.

[0070] The output terminal of the converter can be connected to the power grid, and the processor 130 can use a band-pass filter for filtering the frequency band of the power grid to filter the difference between the output of the inverting amplifier and the output of the non-inverting amplifier, and compare the amplitude level of the filtered difference between the output of the inverting amplifier and the output of the non-inverting amplifier with a reference level to detect a fault. When the amplitude level of the filtered difference between the output of the inverting amplifier and the output of the non-inverting amplifier is less than the reference level for a predetermined time period, the processor 130 can determine that a fault has occurred. When a fault is detected, the processor 130 can block the connection of at least one of the input terminal or the output terminal of the converter. This will protect the entire system.

[0071] The converter 1000 can be a DC-DC converter inside the battery pack, and the processor 130 can detect a contact or ground fault of the battery in the battery pack. Alternatively, the converter 1000 can be a DC-DC converter connected to the photovoltaic module, and the processor 130 can detect a contact or ground fault of at least one of the two ends of the input terminal of the photovoltaic module of the DC-DC converter.

[0072] Figure 11 is a block diagram of a battery pack according to an embodiment of the present invention.

[0073] The battery pack 1100 according to an embodiment of the present invention includes a battery 1110, a DC-DC converter 1000 for converting the voltage of the battery 1110, and a fault detection circuit for detecting a contact or ground fault in the battery 1110. The detailed description of the DC-DC converter 1000 and the fault detection circuit of the battery pack 1100 according to an embodiment of the present invention corresponds to Figures 1 to 9 the fault detection device of Figure 10 and the detailed description of the DC-DC converter of

[0074] The battery pack 1100 of the present invention can convert the power of the internally provided battery 1110 into power through the DC-DC converter 1000 to output power, and the output power can be sent to the power grid through an inverter. Alternatively, it can receive power from the photovoltaic panel or the power grid to convert the power and then charge the battery.

[0075] The fault detection circuit detects a contact or ground fault of at least one terminal at both ends of the battery 1110. The fault detection circuit may include a plurality of resistors 110 connected in series between both ends of the battery 1110, a sensing circuit 120 that measures a first voltage at one of the nodes between the plurality of resistors, and a processor 130 that detects a fault by using a change in the first voltage.

[0076] Here, the plurality of resistors may include a first resistor, a second resistor, and a third resistor, which are sequentially connected in series from the positive terminal of the input terminal 210 to the negative terminal of the input terminal 210. The node between the first resistor and the second resistor is connected to the housing of the battery pack 1100, and the sensing circuit 120 may measure the first voltage at the node between the second resistor and the third resistor. The sensing circuit 120 may include an inverting amplifier and a non-inverting amplifier - each of the inverting amplifier and the non-inverting amplifier receives the first voltage, and the output of each of the outputs of the inverting amplifier and the non-inverting amplifier may be applied to the processor 130.

[0077] In addition, a first low-pass filter for filtering the output of the inverting amplifier and a second low-pass filter for filtering the output of the non-inverting amplifier may be provided, and the output of the inverting amplifier and the output of the non-inverting amplifier may be applied to the processor 130 through the first low-pass filter and the second low-pass filter, respectively, and the processor 130 may detect a fault by using the difference between the output of the inverting amplifier and the output of the non-inverting amplifier.

[0078] The output terminal of the converter may be connected to the power grid, and the processor 130 may use a band-pass filter that filters the frequency band of the power grid to filter the difference between the output of the inverting amplifier and the output of the non-inverting amplifier, and compare the amplitude level of the filtered difference between the output of the inverting amplifier and the output of the non-inverting amplifier with a reference level to detect a fault. When the amplitude level of the difference between the output of the inverting amplifier and the output of the non-inverting amplifier after filtering is less than the reference level for a predetermined period of time, the processor 130 may determine that a fault has occurred. When a fault is detected, the processor 130 may block the circuit breaker (CB), which is a circuit breaker connected to the output terminal of the battery pack 1100 to control the on / off of the connection with the outside. This will protect the entire system.

[0079] Figure 12 is a flowchart of a fault detection method according to an embodiment of the present invention, and Figure 13 is a flowchart of a fault detection method according to an embodiment of the present invention. Figure 12 and Figure 13 The detailed description of each process inFigures 1 to 11 Detailed description of the fault detection device, and any repeated descriptions will be briefly described below.

[0080] In order to detect a contact or ground fault of a battery or a photovoltaic panel connected to the input terminal of a DC-DC converter, in operation S11, a first voltage is sensed from a fault detection circuit connected to both ends of the input terminal.

[0081] Here, the fault detection circuit may include: a plurality of resistors connected in series between both ends of the battery; and a sensing circuit that measures a first voltage at one of the nodes between the plurality of resistors to detect a fault by using a change in the first voltage. The plurality of resistors may include a first resistor, a second resistor, and a third resistor, and the first resistor, the second resistor, and the third resistor are sequentially connected in series from the positive terminal of the input terminal to the negative terminal of the input terminal. The node between the first resistor and the second resistor may be connected to the housing of the converter, and the sensing circuit may measure the first voltage at the node between the second resistor and the third resistor.

[0082] Thereafter, in operation S12, the magnitude level of the difference between the values obtained by inverting and non-inverting the first voltage is calculated and then compared with a reference level to detect whether a fault exists. The sensing circuit may include an inverting amplifier and a non-inverting amplifier - each of the inverting amplifier and the non-inverting amplifier receives the first voltage, and the output of the inverting amplifier and the output of the non-inverting amplifier may be used to detect whether a fault exists. Here, a first low-pass filter for filtering the output of the inverting amplifier and a second low-pass filter for filtering the output of the non-inverting amplifier may be provided to receive the output of the inverting amplifier and the output of the non-inverting amplifier through the first low-pass filter and the second low-pass filter, respectively, and a fault may be detected by using the difference between the output of the inverting amplifier and the output of the non-inverting amplifier.

[0083] The output terminal of the converter may be connected to the power grid, and a band-pass filter for filtering the frequency band of the power grid may be used to filter the difference between the output of the inverting amplifier and the output of the non-inverting amplifier, and a fault may be detected by comparing the magnitude level of the difference between the filtered output of the inverting amplifier and the output of the non-inverting amplifier with a reference level. Here, when the magnitude level of the difference between the filtered output of the inverting amplifier and the output of the non-inverting amplifier is less than the reference level for a predetermined period of time, it may be determined that a fault has occurred.

[0084] When a failure is detected in operation S12, the connection to the outside can be blocked in operation S21. When a failure is detected, the system can be protected by opening the circuit breaker (CB), which connects and disconnects the connection to the outside.

[0085] In addition, embodiments of the present invention can also be embodied as computer-readable code on a computer-readable recording medium. The computer-readable recording medium includes all types of recording devices that store data readable by a computer system.

[0086] Examples of the computer-readable storage medium may include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc., and furthermore, the computer-readable storage medium may be distributed on network-connected computer systems, so that the computer-readable code is stored and executed in a distributed manner. In addition, the functional programs, codes, and code segments for implementing the present invention can be easily interpreted by programmers in the field to which the present invention pertains.

[0087] Those skilled in the art will understand that various changes in form and detail can be made therein without departing from the spirit and scope of the present invention defined by the appended claims. Therefore, the disclosed method should be considered in a descriptive sense only and not for purposes of limitation. Thus, the scope of the present invention is not defined by the detailed description of the present invention but by the appended claims, and all differences within that scope will be construed as being included in the present invention.

Claims

1. A fault detection device, comprising: a plurality of resistors connected in series between two ends of an input terminal of a converter; a sensing circuit configured to measure a first voltage at one of the nodes between the plurality of resistors; and a processor configured to detect a fault by using a change in the first voltage.

2. The fault detection device according to claim 1, wherein The plurality of resistors includes a first resistor, a second resistor, and a third resistor, and the first resistor, the second resistor, and the third resistor are sequentially connected in series from the positive terminal of the input terminal to the negative terminal of the input terminal, wherein a node between the first resistor and the second resistor is connected to a housing of the converter, and wherein the sensing circuit measures the first voltage at a node between the second resistor and the third resistor.

3. The fault detection device according to claim 1, wherein, The sensing circuit includes an inverting amplifier and a non-inverting amplifier, and wherein an output of the inverting amplifier and an output of the non-inverting amplifier are applied to the processor.

4. The fault detection device according to claim 3, comprising: a first low-pass filter configured to filter an output of the non-inverting amplifier; and a second low-pass filter configured to filter an output of the inverting amplifier, wherein the output of the inverting amplifier and the output of the non-inverting amplifier are respectively applied to the processor through the first low-pass filter and the second low-pass filter.

5. The fault detection device according to claim 3, wherein, The processor detects a fault by using a difference between the output of the inverting amplifier and the output of the non-inverting amplifier.

6. The fault detection device according to claim 5, wherein, An output terminal of the converter is connected to a power grid, and wherein the processor is configured to: filter a difference between the output of the inverting amplifier and the output of the non-inverting amplifier by using a band-pass filter configured to filter a frequency band of the power grid; and compare an amplitude level of the filtered difference between the output of the inverting amplifier and the output of the non-inverting amplifier with a reference level and detect the fault.

7. The fault detection device according to claim 6, wherein, When the amplitude level of the filtered difference between the output of the inverting amplifier and the output of the non-inverting amplifier is less than the reference level for a predetermined period of time, the processor determines that the fault has occurred.

8. The fault detection device according to claim 1, wherein When the fault is detected, the processor blocks a connection of at least one of the input terminal or the output terminal of the converter.

9. The fault detection device according to claim 1, wherein, The converter includes a DC-DC converter inside a battery pack, and wherein the processor detects a contact fault or a ground fault of a battery of the battery pack.

10. The fault detection device according to claim 1, wherein, The converter includes a DC-DC converter connected to a photovoltaic module, and wherein the processor detects a contact fault or a ground fault of at least one of two ends of an input terminal of the photovoltaic module of the DC-DC converter.

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