KR20150025428A - Apparatus and Method for diagnosis of cell balancing switch - Google Patents

Abstract

Disclosed are an apparatus and a method for diagnosing malfunction of a cell balancing switch. The apparatus for diagnosing malfunction of a cell balancing switch according to the present invention turns on or off a switch to be diagnosed and analyzes malfunction of the cell balancing switch by analyzing a variation pattern of a node voltage to be diagnosed during turn-on and turn-off. When it is determined that a switch to be analyzed is malfunctioning, the apparatus turns on the cell balancing switch adjacent to the switch to be diagnosed, analyzes a node voltage of the cell adjacent to the switch to be diagnosed, and determines a reason for the malfunction of the cell balancing switching to be diagnosed. According to the invention, the cell balancing switch can be diagnosed for malfunction and a reason for the malfunction by using a simple circuit configuration.

Description

[0001] Apparatus and method for diagnosing a cell balancing switch [

The present invention relates to an apparatus and method for diagnosing a fault in a cell balancing switch, and more particularly, to a cell balancing circuit using a discharge resistor, a cell balancing switch for switching the flow of a discharge current, And more particularly, to a fault diagnosis apparatus and method for a balancing switch.

Due to the recent exhaustion of fossil energy and environmental pollution, interest in electric vehicles and hybrid vehicles that use electric energy instead of using fossil energy has been actively studied. An electric vehicle or hybrid vehicle is equipped with a battery pack composed of a plurality of battery cells for driving a driving motor for driving a vehicle and supplying power required for operating various electric devices. A plurality of battery cells included in such a battery pack needs to maintain the voltage of each battery cell uniformly in order to obtain stability, life span, and high output.

Methods for uniformly balancing the charging voltage of each battery cell included in the battery pack include a method of increasing the voltage by supplying a charging current to a battery cell having a relatively low voltage, a method of discharging a battery cell having a relatively high voltage, A method of determining a balancing target voltage from a voltage of each battery cell, a method of discharging a battery cell having a higher voltage than the target voltage, and a method of charging a battery cell having a voltage lower than the target voltage.

Such a cell balancing method is implemented by a cell balancing circuit connected to each battery cell. The cell balancing circuit includes a switching element for controlling the start and end of the cell balancing operation and a discharging resistor used for discharging the battery cell voltage.

However, during the cell balancing operation using the cell balancing circuit, an excessive current flows into the cell balancing circuit instantaneously, an overvoltage higher than the operating voltage is applied to the switching element, or excessive heat is generated due to the discharge resistance The components included in the balancing circuit are short-circuited or open so that the circuit does not operate normally.

If the cell balancing circuit does not operate normally, the voltage of the battery cell connected to the circuit becomes excessively high or low as compared with other battery cells, so that the operation of the load connected to the battery pack suddenly stops, Problems may arise.

In order to solve the above problem, it is necessary that a diagnostic circuit capable of diagnosing the abnormality of the cell balancing circuit is combined with the cell balancing circuit.

For example, Korean Patent Registration No. 10-1065562 discloses a method of analyzing a pattern of a voltage difference by turning on and off an adjacent cell balancing switch to determine whether any of the cell balancing switches is faulty.

However, the above-described prior art is based on the assumption that the cell balancing switch to be diagnosed and the other cell balancing switch adjacent to the cell are operating normally. That is, if the adjacent cell balancing switch is in a failed state, the diagnosis may not be performed correctly. Further, if a failure occurs in two or more cell balancing switches, there is a problem that the method disclosed in the prior art can not be performed.

SUMMARY OF THE INVENTION The present invention provides a fault diagnosis apparatus and method for a cell balancing switch capable of accurately diagnosing whether a cell balancing switch is faulty or faulty with a simple circuit configuration, There is a purpose.

According to an aspect of the present invention, there is provided an apparatus for diagnosing a failure of a cell balancing switch corresponding to each cell in a battery pack including a plurality of cells, A cell balancing circuit connected in parallel to the connected voltage sensing line and including the cell balancing switch and the discharging resistor; A diagnostic resistor provided on the cell-side voltage sensing line with respect to a node (high-potential node and low-potential node) to which the cell balancing circuit and the cell voltage sensing line are connected; A voltage sensing circuit for outputting a voltage corresponding to a voltage difference between the high potential node and the low potential node (hereinafter referred to as node voltage difference); And a controller for determining whether the cell balancing switch is malfunctioning by analyzing a change pattern of a node voltage to be diagnosed when the switch is turned on or turned off at the time of turning on and turning off the switch to be diagnosed among the cell balancing switches, The cell balancing switch adjacent to the switch to be diagnosed is turned on to analyze the node voltage of the cell adjacent to the switch to be diagnosed upon turning on to determine the cause of the failure of the cell balancing switch to be diagnosed.

The apparatus for diagnosing a cell balancing switch according to the present invention may further include a diode for limiting a voltage applied to a low potential node on the cell balancing circuit in a reverse direction.

The cell balancing switch according to the present invention may be a field effect transistor (FET).

According to an embodiment of the present invention, when the difference between the node voltage difference in the turn-on state of the diagnostic object cell balancing switch and the node voltage difference in the turn-off state is equal to or less than a preset reference voltage, .

According to an embodiment of the present invention, when the node voltage difference in the on-state of the cell balancing switch adjacent to the switch to be diagnosed is larger than the voltage value dropped by the two diagnostic resistors, Is short-circuited.

According to an embodiment of the present invention, when the node voltage difference in the ON state of the cell balancing switch adjacent to the switch to be diagnosed is smaller than the voltage value dropped by the two diagnostic resistors, Is disconnected.

The apparatus for diagnosing faults in a cell balancing switch according to the present invention further comprises a fault alarm notifying the occurrence of a fault when a fault occurs in the cell balancing switch, and the control unit can visually or audibly It is possible to notify the occurrence of a failure of the cell balancing switch.

A fault diagnosis apparatus for a cell balancing switch according to the present invention includes: a fault diagnosis apparatus for a cell balancing switch; And a plurality of cells.

A battery pack according to the present invention includes a battery pack; And a load that is supplied with electric power from the battery pack. In this case, the load may be electric driving means or a portable device.

According to an aspect of the present invention, there is provided a method of diagnosing a cell balancing switch, the method comprising: connecting a cell balancing switch and a discharge resistor in parallel in a voltage sensing line connected to both terminals of each cell in a battery pack including a plurality of cells; A diagnostic resistor provided on a cell-side voltage sensing line based on a node (a high potential node and a low potential node) to which the cell balancing circuit and the cell voltage sensing line are connected, and a high- A method for diagnosing a failure of a cell balancing switch using a voltage sensing circuit for outputting a voltage corresponding to a voltage difference between nodes (hereinafter node voltage difference), comprising the steps of: (a) Or turn off to analyze the change pattern of the node voltage to be diagnosed at the time of turning on and turning off, Determining whether a failure; And (b) if the switch to be diagnosed is determined to be faulty, the cell balancing switch adjacent to the switch to be diagnosed is turned on to analyze the node voltage of the adjacent cell and the cell to be diagnosed when the switch is turned on, And determining a cause of the failure of the switch.

According to an embodiment of the present invention, in the step (a), when the difference value between the node voltage difference in the turn-on state of the diagnostic object cell balancing switch and the node voltage difference in the turn-off state is equal to or less than a preset reference voltage, It is determined that there is a failure.

According to an embodiment of the present invention, in the step (b), when the node voltage difference in the turn-on state of the cell balancing switch adjacent to the switch to be diagnosed is larger than the voltage value dropped by the two diagnostic resistors, It is determined that the cell balancing switch is short-circuited.

According to an embodiment of the present invention, in the step (b), when the node voltage difference in the turn-on state of the cell balancing switch adjacent to the switch to be diagnosed is smaller than the voltage value dropped by the two diagnostic resistors, It is determined that the cell balancing switch is disconnected.

The method for diagnosing a fault in a cell balancing switch according to the present invention further comprises a fault alarm notifying the occurrence of a fault when a fault occurs in the cell balancing switch, and (c) And notifying the occurrence of a failure of the cell balancing switch.

According to the present invention, it is possible to diagnose whether or not the cell balancing switch is faulty and the cause of failure by a simple circuit configuration. Further, even when the voltage sensing line is disconnected or when the entire cell balancing switch is disconnected or short-circuited, the cause of the failure can be accurately determined. This makes it possible to prevent the failure of the battery from spreading beyond the cell balancing circuit.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description of the invention given below, serve to further the understanding of the technical idea of the invention, And should not be construed as limiting.
1 is a circuit diagram of a fault diagnosis apparatus for a cell balancing switch according to a preferred embodiment of the present invention.
FIGS. 2 to 4 are diagrams illustrating a method of determining whether a cell balancing switch is faulty or fail according to a preferred embodiment of the present invention.
5 and 6 are flowcharts illustrating a method of diagnosing a failure of a cell balancing switch according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined. Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

1 is a circuit diagram of a fault diagnosis apparatus for a cell balancing switch according to a preferred embodiment of the present invention. Although only three cells are illustrated in Fig. 1, the present invention is not limited by the number of cells.

1, the failure diagnostic system for the cell balancing switch according to the present invention, a plurality of cells (VB1, VB2, VB3), the battery pack 10, each cell (VB _1, VB _2, VB ₃₎ in containing the A cell balancing circuit 20 connected in parallel to a voltage sensing line connected to both terminals of the cell balancing circuit 20 and including a cell balancing switch SW _b1 , SW _b2 , SW _b3 and a discharging resistor R _d , A diagnostic resistor R _m provided on the cell-side voltage sensing line with reference to the node (high-potential node A and low-potential node B) to which the cell voltage sensing line is connected, A voltage sensing circuit 30 for sensing and outputting a voltage corresponding to a voltage difference between nodes B (hereinafter referred to as a node voltage difference), and a voltage sensing circuit 30 for turning on or off the cell balancing switch SW _b , And the voltage difference between the nodes at the time of turn-off are analyzed to determine whether the cell balancing switch is faulty or not, A controller 40 for determination.

The high potential node A and the low potential node B are connected to the positive electrode of the _first cell VB ₁ at a relative position where the cell balancing circuit 20 is connected to the cell voltage sensing line The point where the extended cell voltage sensing line and the cell balancing circuit 20 are connected becomes a high potential node A and this high potential node A again connects to the cathode of the _second cell VB ₂ And becomes a low potential node B at a point where the cell voltage sensing line and the cell balancing circuit 20 are connected.

The cell balancing circuit 20 is controlled by the cell balancing switches SW _b1 , SW _b2 and SW _b3 whose operation is controlled by the controller 40 and the cell balancing switches SW _b1 , SW _b2 and SW _b3 , And a discharge resistor R _d for discharging a voltage charged in the cell (hereinafter referred to as a cell voltage). Although not essential, a diode D may be further included on the low potential node B side of the cell balancing circuit 20 to limit the application of the voltage in the reverse direction. The cell balancing switches SW _b1 , SW _b2 and SW _b3 are preferably field effect transistors (FETs). A field-effect transistor (FET) has a source terminal, a drain terminal and a gate terminal. A gate voltage is applied to the gate terminal of the field-effect transistor under the control of the control unit 40, and the cell balancing circuit 20 And the cell voltage is discharged through the discharge resistor R _d . The circuit configuration and the operation method of the field effect transistor (FET) in the embodiment of the present invention are not essential points, so that detailed description will be omitted.

The diagnostic resistor (R _m) is the cell balancing switch as a component for diagnosing a failure of the _{(SW b1, SW b2, SW} b3), the discharge current through the discharge resistor (R _d) when the discharge cell voltage in the present invention And the voltage difference between the nodes when there is no current flow. That is, when the cell balancing switches SW _b1 , SW _b2 , and SW _b3 are turned on or the cell balancing switches SW _b1 , SW _b2 , and SW _b3 are short-circuited, a discharge current flows through a discharge loop indicated by an arrow. In this case, the potential of the high potential node is reduced as compared with the case where the discharge current does not flow due to the discharge current flowing in the diagnostic resistance (R _m ) on the high potential node side, and the potential of the low potential node is reduced due to the discharge current flowing through the R _m) is increased compared to the case where the discharging current does not flow. As a result, when a discharge current flows through the discharge loop, the voltage difference between the nodes becomes smaller than when the discharge current does not flow. On the contrary, when the cell balancing switches SW _b1 , SW _b2 and SW _b3 are turned off or the cell balancing switches SW _b1 , SW _b2 and SW _b3 are disconnected, no discharge current flows in the discharge loop. And has a voltage value at the same level as the cell voltage. If a discharge current does not flow through the discharge loop, a voltage drop through the diagnostic resistor R _m is not generated and the cell voltage is directly applied between the nodes.

The voltage sensing circuit 30 includes a cell balancing switch cell balancing switch under the control of the control unit 40 for the purpose of diagnosing a failure of the (SW _b1, SW _b2, SW _b3), (SW _b1, SW _b2, SW _b3 Is turned on / off, the voltage difference between the high potential node A and the low potential node B of each cell is sensed and output as an analog voltage signal.

Preferably, the voltage sensing circuit 30 is used in a circuit that is commonly used to periodically sensing the voltage of each cell (VB _1, VB _2, VB ₃₎ as it is. In this case, there is an advantage that a separate voltage sensing circuit is not required for the purpose of diagnosing a failure of the cell balancing switches SW _b1 , SW _b2 , and SW _b3 .

The control unit 40 includes an A / D conversion module (not shown) for converting an analog voltage signal output from the voltage sensing circuit 30 into a digital voltage signal, and a digital voltage conversion unit And controls the operation of the cell balancing switches SW _b1 , SW _b2 and SW _b3 to obtain a voltage difference between the nodes of the cells VB ₁ , VB ₂ and VB ₃ , A central operation module (not shown) for analyzing the change pattern of the inter-node voltage difference of each cell obtained by using the sensing circuit 30 to determine whether the cell balancing switches SW _b1 , SW _b2 , SW _b3 are faulty or not, ). Since the configuration of the control unit 40 is generally known to be used in a system for controlling a battery, detailed description will be omitted.

Cell balancing switch that failure diagnostic system for the cell balancing switch according to an embodiment of the present invention for the cell balancing switches _{(SW b1, SW b2, SW} b3) a second time cell (VB ₂₎ the step of determining the failure of the (SW _b2 ) will be described as follows.

First, the controller 40 turns on the cell balancing switch SW _b2 of the _second cell VB ₂ to be diagnosed. At this time, the cell balancing switches SW _b1 and SW _{b3 of} the first cell (VB ₁ ) and the third cell (VB ₃ ) adjacent to the _second cell (VB ₂ ) are connected to the second cell (VB ₂ ) So that it is turned off. Then, the voltage difference between the nodes of the _second cell (VB ₂ ) is sensed through the voltage sensing circuit (30) and stored. Then, the control unit 40 is the second time cell (VB _2), the cell balancing switches (SW _b2) the turn was turned off, the second time a cell voltage difference of the voltage sensing circuit 30 between the nodes of the (VB ₂₎ of the And stores it. Then, when the cell balancing switch SW _b2 of the second cell VB ₂ is turned on or off, the control unit 40 analyzes the change pattern of the voltage difference between the adjacent cells to determine whether the cell balancing switch is malfunctioning And the cause of the failure.

< Case  1: cell of the second cell Balancing  When the switch is normal>

As shown in FIG. 2, the high-potential terminal voltage of the second cell VB ₂ will be referred to as VB _{2 (+)} and the low-potential terminal voltage as VB _{2 (-)} . A high-potential node to which the cell voltage sensing line connected to the anode of the _second cell (VB ₂ ) and connected to the cell balancing circuit (20) is referred to as 'A ₂ ' for distinction from other nodes, And a low potential node to which the cell balancing circuit 20 is connected to the cell voltage sensing line connected to the cathode of the cell VB ₂ will be referred to as 'B ₂ '.

When the 2-cell (VB ₂₎ cell balancing switches (SW _b2) is turned on, the discharge current flows in the discharge loop of the second time cell (VB _2). At this time, the current flowing in the discharge loop will be referred to as 'I ₂ '. Therefore, the voltage of the high potential node 'A ₂ ' becomes 'VB _{2 (+) -} I ₂ * R _m '. The voltage of the low potential node 'B ₂ ' becomes 'VB _{2 (-)} + I ₂ * R _m '. And a second time difference between the voltage between the node of the cell _{(VB 2) '{VB 2} (+) -I 2 * R m} - {VB 2 (-) + I 2 * R m} = cell voltage of the VB ₂ -2 * (I ₂ * R _m ) '.

On the other hand, when the cell balancing switch SW _b2 of the second cell VB ₂ is turned off, no current flows. Therefore, the voltage of the high potential node 'A ₂ ' is VB _{2 (+)} and the voltage of the low potential node 'B ₂ ' is VB _{2 (-)} . The second time the voltage difference between the nodes of the cells (VB _{2) -} are the 'VB _{2 (+)} -VB ₂ cell voltage = VB _{2 ()'.}

The control portion 40 of the second time cells (VB2), the cell balancing switches (SW _b2) a second time the cell voltage difference and the second time cell (VB ₂₎ between the nodes of the (VB ₂₎ of when the turn-off of the And analyzes the pattern change of the voltage difference between the nodes of the second cell (VB ₂ ) when the cell balancing switch (SW _b2 ) is turned on.

According to an embodiment of the present invention, when the difference between the node voltage difference in the ON state and the node voltage difference in the turn OFF state is equal to or less than the preset reference voltage, the controller 40 controls the cell balancing switch It is determined that there is a failure. The 'predetermined voltage' may be set to a predetermined value such as a range of the operating voltage of the cells VB ₁ , VB ₂ and VB ₃ , a resistance value of each diagnostic resistance R _m , a resistance value of each cell balancing resistance R _d , Can be variously set in consideration of. Preferably, the predetermined voltage is a value for determining that the change in the voltage value is small irrespective of the turn-on and turn-off control of the cell balancing switch for diagnosis of the controller 40 when the cell balancing switch for diagnosis is failed, The closer to 0V, the better.

Therefore, the cell balancing switch of claim 2 cells (VB ₂₎ cell balancing switch of claim 2 cells (VB ₂₎ the voltage difference and the second time cell (VB ₂₎ between nodes of when (SWb2) the turn-off of the ( 2 * (I ₂ * R _m ) 'by calculating the difference value of the voltage difference between the nodes of the second cell VB ₂ when the switches SWb 1 and SWb 2 are turned on. For example, when the preset voltage is set to '0V', the difference value '2 * (I ₂ * R _m )' of the voltage difference between the nodes of the _second cell VB ₂ is greater than or equal to OV I have. Accordingly, the controller 40 determines that the cell balancing switch to be diagnosed is operating normally.

< Case  2: cell of the second cell Balancing  If the switch is faulty>

On the other hand, it is assumed that a failure occurs in the cell balancing switch SW _b2 of the second cell VB ₂ . The cell balancing switch SWb2 of the _second cell VB2 will not operate in response to the control signal of the controller 40 whether the type of the fault is short or open. Therefore, the cell balancing of the second time cell (VB ₂₎ cell balancing switches (SW _b2) is the node-to-node voltage of 2 cells (VB ₂₎ difference and the second time cell (VB ₂₎ of when the turn-off of the The voltage difference between the nodes of the second cell VB ₂ when the switch SW _b2 is turned on will be the same. That is, the difference value of the voltage difference between the nodes of the _second cell VB ₂ becomes '0'. When the preset voltage is set to '0V' as in the above example, the difference value of the voltage difference between the nodes of the _second cell VB ₂ is equal to or less than 'OV'. Therefore, the control unit 40 determines that the cell balancing switch to be diagnosed has failed.

Therefore, a method for determining the cause of the failure will be described below.

< Case  2-1: cell of the second cell Balancing  If the switch is shorted>

First, it is assumed that the cell balancing switch SW _b2 of the second cell VB ₂ is short-circuited.

The apparatus for diagnosing a fault of the cell balancing switch according to the present invention turns on or off all the cell balancing switches SW _{b1 and} SW _b3 adjacent to the switch SW _b2 to be diagnosed _, cell balancing switches (SW _b1, SW _b3) any one of the cell balancing switches (SW _b1) a switch that is diagnosed during turn-on to turn-on (SW _b2 of instead of, adjacent to a switch (SW _b2) is diagnosed ) To determine the cause of the failure of the cell balancing switch SW _b2 . In this specification, the first cell balancing switch SW _b1 among the adjacent cell balancing switches SW _{b1 and} SW _b3 is turned on to determine the cause of the failure of the second cell balancing switch SW _b2 Let me explain.

Will la _- 'VB _{1 ()',} and as shown in FIG. 3, the 'VB _{1 (+)'} to the high-potential terminal voltage of the cell # 1 (VB ₁₎ referred to, and the low-potential terminal voltage.

Further, the above-described extended by connecting the positive electrode of the node above the anode and the adjacent classic 2 cells (VB ₂₎ (A ₂₎ and to distinguish them from the low-potential node (B _2), the cell of claim times ₁ (VB 1) the cell voltage sensing line and the cell balance circuit 20 is a high-potential node to be connected 'a _1' is called, and the second (VB ₁₎ 1 times the cell cathode and connected by an extended cell voltage sensing line of the cell balancing circuit ( 20 will be referred to as &quot; B ₁ &quot;. Naturally, the high-potential node A ₁ adjacent to the anode of the _first cell VB ₁ is the same node as the low-potential node B ₂ adjacent to the cathode of the second cell VB ₂ .

3, if the cell balancing switch SW _b2 of the _second cell VB ₂ is short-circuited, regardless of whether the cell balancing switch SW _b2 is turned on or off, Flows. On the other hand, the time when the first cell (VB ₁₎ cell balancing switches (SW _b1) is turned on, the discharge current flows in the discharge loop of the first one cell (VB _1). At this time, the current flowing in the discharge loop will be referred to as 'I ₁ '. 'I ₁ ' and 'I ₂ ' having opposite directions flow through the diagnostic resistor R _m connected to the high potential terminal of the first cell VB ₁ . Wherein if the first number is equal to the voltage of the voltage and the second time cell (VB ₂₎ of the cell (VB _1), it is 'I _1' and 'I _2' are the same and only the opposite direction of the current size. Therefore, no current flows through the diagnostic resistor R _m connected to the high potential terminal of the first cell VB ₁ . On the other hand, the first, even if the voltage of the voltage and the second time cell (VB ₂₎ of the # 1 cells (VB ₁₎ not the same, the first time the cell (VB ₁₎ and the second time cell (VB ₂₎ is Since they are included in one battery pack, they will have similar voltage values. That is, the size difference between 'I ₁ ' and 'I ₂ ' would be very small. Therefore, only a small current which can be ignored will flow through the diagnostic resistor R _m connected to the high potential terminal of the first cell VB ₁ . Therefore, when the cell balancing switch SW _b1 of the first cell VB ₁ is turned on, the voltage of the high potential node A ₁ becomes VB _{1 (+)} . On the other hand, when the cell balancing switch SW _b1 of the first cell VB ₁ is turned on, the voltage of the low potential node B ₂ is VB _{1 (-)} + I ₁ * R _m '. Therefore, the first cell balancing switch of No. 1 cells (VB ₁₎ (SW _b1) is the voltage difference between nodes of the first one cell _{(VB 1) '{VB 1} (+)} of when the turn-on - {VB _{1 ( -)} + I ₁ * R _m } = {cell voltage of VB ₁ -I ₁ * R _m } '.

According to an embodiment of the present invention, when the node voltage difference in the turn-on state of the cell balancing switch adjacent to the switch to be diagnosed is larger than the voltage dropped voltage value caused by the two diagnostic resistors, It is determined that the cell balancing switch is short-circuited.

Therefore, the cell balancing switches of the first one cell (VB ₁₎ cell balancing switches (SW _b1) a first time cell (VB ₁₎ voltage difference between the first time the cell (VB ₁₎ between nodes of when the turn-on of ( SW _b1), so that the "cell voltage -I1 * Rm of VB _1, the difference in voltage between the nodes # 1 cells (VB _1), the voltage drop {2 by the two diagnostic resistance * (I ₁ * R of when the turn-on _m )}. Therefore, the control unit 40 determines that the cell balancing switch SW _b2 of the _second cell VB ₂ is short-circuited to be faulty.

< Case  2-2: cell of the second cell Balancing  When the switch is disconnected>

First, it is assumed that the cell balancing switch SW _b2 of the second cell VB ₂ is broken by an open circuit.

As shown in Figure 4, if it is, the cell balancing switches (SW _b2) disconnection of the 2-cell (VB ₂₎ current according to the cell # 2 (VB ₂₎ (I ₂₎ that does not flow. At this time, the cell balancing when the switch (SW _b1) is turned on in # 1 cells (VB ₁₎ flows through the first time the cell discharge current (I ₂₎ to the discharge loop of the (VB _1). Therefore, the voltage of the high potential node 'A ₁ ' becomes 'VB _{1 (+) -} I ₁ * R _m '. Further, the voltage of the low potential node 'B ₁ ' becomes 'VB _{1 (-)} + I ₁ * R _m '. And the node between the voltage difference between the cell # 1 _{(VB 1) '{VB 1} (+) -I 1 * R m} - {VB 1 (-) + I 1 * R m} = { cell voltage VB ₁ - 2 * (I ₁ * R _m )} '.

According to an embodiment of the present invention, when the node voltage difference in the turn-on state of the cell balancing switch adjacent to the switch to be diagnosed is smaller than the voltage dropped voltage value caused by the two diagnostic resistors, It is determined that the cell balancing switch is disconnected.

Therefore, the cell balancing switches of the first one cell (VB ₁₎ cell balancing switches (SW _b1) a first time cell (VB ₁₎ voltage difference between the first time the cell (VB ₁₎ between nodes of when the turn-on of the ( Since SW _b1) a first node between the voltage difference between the cell # 1 (VB ₁₎ 'of the cell voltage _{VB 1 -2 * (I 1 *} R m)' of when the turn-on, the control unit 40 the second time The cell balancing switch SW _b2 of the cell VB ₂ is disconnected to determine that it has failed.

In addition, the fault diagnosis apparatus for the cell balancing switch according to the present invention may further include a fault alarm (not shown) for notifying the occurrence of a fault and the cause of the fault to the outside when a fault occurs in the cell balancing switch. When it is determined that there is a failure in the cell balancing switch, the controller 40 transmits a failure occurrence signal to the failure alarm, and notifies the occurrence of a failure and failure cause of the cell balancing switch to the outside through a failure alarm visually or audibly.

The fault alarm includes an LED, an LCD, an alarm alarm, or a combination thereof. In this case, when the failure occurrence signal is input, the failure alarm may flash the LED, output a warning message to the LCD, or generate an alarm buzzer sound to notify the user of the failure of the cell balancing switch and the cause of the failure. It should be understood that the LED, LCD and alarm alarm are merely examples of a fault alarm, and that various modified forms of visual or audible alarm devices can be employed as fault alarms, Be clear to those who have.

Meanwhile, the fault diagnosis apparatus of the cell balancing switch according to the present invention may be a component of the battery pack 10 including a plurality of cells.

The battery pack 10 according to the present invention may be a component of the battery driving system including the battery pack 10 and a load supplied with power from the battery pack 10. [

Examples of the battery driving system include an electric vehicle (EV), a hybrid vehicle (HEV), an electric bicycle (E-Bike), a power tool, an energy storage system, an uninterruptible power supply (UPS) A battery pack, a portable computer, a portable telephone, a portable audio device, a portable video device, and the like. An example of the load is a power supplied from a motor or a battery pack, And may be a power conversion circuit for converting the power into a required power.

5 and 6 are flowcharts illustrating a method of diagnosing a failure of a cell balancing switch according to an embodiment of the present invention. In Fig. 5, the main body that performs the respective operations is the control unit 40. Fig.

First, in step S10, the diagnosis target cell balancing switch SW _b2 is turned off.

In step S11, the voltage difference between the nodes to be diagnosed (VB ₂ ) is sensed and stored while the diagnosis target cell balancing switch SW _b2 is turned off.

Next, in step S12, the cell balancing switch SW _b2 to be diagnosed is turned on.

In step S13, the diagnosis target cell balancing switches (SW _b2) a diagnostic target cell in a state of turn-on (VB _2), and stores the sensed voltage difference between the nodes.

The order of steps S10, S11, S12, and S13 may be mutually changed.

In step S14, the control unit 40, the cell balancing switches (SW _b2) is turned between the diagnosis target cell (VB ₂₎ when off is the node voltage difference and diagnosis target cell (VB ₂₎ of the diagnosis target cells (VB2) The pattern variation of the voltage difference between nodes of the cell VB _{2 to be} diagnosed when the cell balancing switch SW _b2 of the cell to be diagnosed is turned on is analyzed.

According to one embodiment of the invention, the cell balancing switch in the diagnostic cell (VB ₂₎ cell balancing switch diagnostic cell voltage difference and diagnostic cell (VB ₂₎ between the nodes of the (VB ₂₎ of when the (SWb2) the turn-off of the It calculates a difference value of the voltage difference between nodes of the diagnostic cell (VB ₂₎ at which the (SWb2) is turned on. Then, it is determined whether the difference value of the voltage difference between nodes of the calculated diagnosis target cell (VB ₂ ) is equal to or lower than a preset reference voltage. If the difference value of the voltage difference between nodes of the calculated diagnostic cell VB ₂ is equal to or lower than the preset reference voltage (YES in step S14), the method proceeds to step S15. On the other hand, if the difference value of the voltage difference between nodes of the calculated diagnosis target cell VB ₂ is equal to or greater than the predetermined reference voltage (NO in step S 14), the method determines that the cell balancing switch to be diagnosed is normal, do. At this time, the termination of the process means that the diagnosis of the cell balancing switch as a diagnosis target has been completed, and it is possible to diagnose whether or not another cell balancing switch is faulty.

On the other hand, cells in the case calculating a reference voltage less than the difference value of the voltage difference between nodes preset diagnostic target cell (VB ₂₎ (YES in step S14), the controller 40 is the diagnostic target cell (VB ₂₎ It is determined that the balancing switch SWb2 has failed, and the process proceeds to step S15.

It turns on any one of the cell balancing switches (SW _b1) of the cell balancing switches (SW _{b1, b3} SW) adjacent to the switch (SW _b2) that is a diagnosis target in step S15.

In step S16, by sensing the voltage difference between nodes of a switch (SW _b2) and the cell balancing switches (SW _b1) diagnosis target cell (VB ₂₎ cells (VB ₁₎ adjacent to and in a state of turning on the adjacent be diagnosed .

In step S17, the node of the diagnosis target cell cell (VB ₁₎ adjacent (VB _2), and at the time when turning on the control unit 40 includes a cell balancing switches (SW _b1) adjacent to the switch (SW _b2) is diagnosed And determines the cause of the failure of the cell balancing switch SW _b2 to be diagnosed.

According to an embodiment of the present invention, the control unit 40 determines whether the node voltage difference in the turn-on state of the cell balancing switch adjacent to the switch to be diagnosed is larger or smaller than the voltage dropped voltage value due to the two diagnostic resistors It is determined whether or not the cell balancing switch to be diagnosed has failed.

If the node voltage of the cell balancing switch adjacent to the switch (SW _b2) in which the diagnosis target (SW _b1) a turn-on state the car is higher than the voltage value of the voltage drop caused by the two diagnostic resistance (YES in step S17), the The method implements the process to step S18. On the other hand, when the node voltage difference in the turn-on state of the cell balancing switch SW _b1 adjacent to the switch SW _{b2 to be} diagnosed is smaller than the voltage dropped voltage value due to the two diagnostic resistors (NO in step S17) The method transitions to step S19.

If the node voltage difference in the turned-on state of the cell balancing switch SW _b1 adjacent to the switch SW _{b2 to be} diagnosed is larger than the voltage dropped voltage value due to the two diagnostic resistors (YES in step S17) The control unit 40 determines that the switch _SWb2 to be diagnosed has failed in a short-circuited state (step S18). On the other hand, the cell balancing switches (NO in step S17) (SW _b1) if a node voltage of the turn-on state the difference is smaller than the voltage value of the voltage drop caused by the two diagnostic resistor adjacent to the switch (SW _b2) to which the diagnosis target , The control unit 40 determines that the switch _SWb2 to be diagnosed has failed in a disconnected state (step S19).

In the next step S20, the controller 40 notifies the occurrence of the failure of the cell balancing switch visually or audibly through the failure alarm. Then, the present invention terminates the process.

According to the present invention, it is possible to diagnose whether or not the cell balancing switch is faulty and the cause of failure by a simple circuit configuration. Further, even when the voltage sensing line is disconnected or when the entire cell balancing switch is disconnected or short-circuited, the cause of the failure can be accurately determined. This makes it possible to prevent the failure of the battery from spreading beyond the cell balancing circuit.

In the meantime, in describing the present invention, each configuration of the present invention shown in FIG. 1 to FIG. 4 should be understood as a logical component rather than a physically separated component.

That is, since each configuration corresponds to a logical component for realizing the technical idea of the present invention, even if each component is integrated or separated, if the functions performed by the logical configuration of the present invention can be realized, And it is to be understood that any component that performs the same or similar function should be construed as being within the scope of the present invention irrespective of the consistency of the name.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not to be limited to the details thereof and that various changes and modifications will be apparent to those skilled in the art. And various modifications and variations are possible within the scope of the appended claims.

10: Battery pack
20: cell balancing circuit
30: Voltage sensing circuit
40:
R _m : diagnostic resistance
R _d : discharge resistance
SW _b1 , SW _b2 , SW _b3 : Cell balancing switch
VB ₁ , VB ₂ , VB ₃ : Cell

Claims (15)

An apparatus for diagnosing a failure of a cell balancing switch corresponding to each cell in a battery pack including a plurality of cells,
A cell balancing circuit connected in parallel to a voltage sensing line connected to both terminals of each cell and including the cell balancing switch and a discharge resistor;
A diagnostic resistor provided on the cell-side voltage sensing line with respect to a node (high-potential node and low-potential node) to which the cell balancing circuit and the cell voltage sensing line are connected;
A voltage sensing circuit for outputting a voltage corresponding to a voltage difference between the high potential node and the low potential node (hereinafter referred to as node voltage difference); And
A switch that is a diagnosis object of the cell balancing switch is turned on or turned off to analyze a change pattern of a node voltage to be diagnosed when the switch is turned on and turned off to determine whether the cell balancing switch is faulty, When the failure is determined, the cell balancing switch adjacent to the switch to be diagnosed is turned on to analyze the node voltage of the cell adjacent to the switch to be diagnosed at the time of turning on, thereby determining the cause of the failure of the cell balancing switch Of the cell balancing switch. The method according to claim 1,
And a diode for limiting a voltage applied in a reverse direction to the low potential node side on the cell balancing circuit. The method according to claim 1,
Wherein the cell balancing switch is a field effect transistor (FET). The method according to claim 1,
Wherein the controller determines that the diagnostic target cell balancing switch is malfunctioning if the difference between the node voltage difference in the turn-on state of the diagnostic target cell balancing switch and the node voltage difference in the turn off state is equal to or less than a preset reference voltage. Fault diagnosis device of switch. The method according to claim 1,
The control unit determines that the diagnosis target cell balancing switch is short-circuited when the node voltage difference in the turn-on state of the cell balancing switch adjacent to the switch to be diagnosed is larger than the voltage value dropped by the two diagnostic resistors Wherein the cell balancing switch is connected to the cell balancing switch. The method according to claim 1,
The control unit determines that the diagnostic target cell balancing switch is disconnected when the node voltage difference in the turn-on state of the cell balancing switch adjacent to the switch to be diagnosed is smaller than the voltage value dropped by the two diagnostic resistors Wherein the cell balancing switch is connected to the cell balancing switch. The method according to claim 1,
Further comprising a failure alarm notifying a failure occurrence to the outside when a failure occurs in the cell balancing switch,
Wherein the controller informs the failure occurrence of the cell balancing switch visually or audibly through the failure alarm. 10. A fault diagnosis apparatus for a cell balancing switch according to any one of claims 1 to 7, And
And a plurality of cells. The battery pack according to claim 8, And
And a load supplied with power from the battery pack. 10. The method of claim 9,
Wherein the load is an electric drive means or a portable device. A cell balancing circuit connected in parallel to a voltage sensing line connected to both terminals of each cell in a battery pack including a plurality of cells, the cell balancing circuit including the cell balancing switch and the discharging resistor; (Hereinafter, referred to as a node voltage difference) between the high potential node and the low potential node (hereinafter, referred to as a node voltage difference) A method for diagnosing a failure of a cell balancing switch using a sensing circuit,
(a) determining whether the diagnostic target cell balancing switch is malfunctioning by analyzing a change pattern of a node voltage to be diagnosed when the switch is turned on or off to turn on or off the switch of the cell balancing switch; And
(b) When the switch to be diagnosed is judged as a failure, the cell balancing switch adjacent to the switch to be diagnosed is turned on to analyze the node voltage of the cell adjacent to the switch to be diagnosed when the switch is turned on, And determining a cause of the failure of the cell balancing switch. 12. The method of claim 11,
In the step (a), when the difference between the node voltage difference in the turn-on state of the diagnosis target cell balancing switch and the node voltage difference in the turn-off state is equal to or less than a predetermined reference voltage, the diagnosis target cell balancing switch is determined to be faulty A method of diagnosing a cell balancing switch. 12. The method of claim 11,
In the step (b), when the node voltage difference in the turn-on state of the cell balancing switch adjacent to the switch to be diagnosed is larger than the voltage value dropped by the two diagnostic resistors, it is determined that the diagnosis target cell balancing switch is short- Wherein the cell balancing switch is connected to the cell balancing switch. 12. The method of claim 11,
In the step (b), when the node voltage difference in the turn-on state of the cell balancing switch adjacent to the switch to be diagnosed is smaller than the voltage value dropped by the two diagnostic resistors, it is determined that the diagnosis target cell balancing switch is disconnected Wherein the cell balancing switch is connected to the cell balancing switch. 12. The method of claim 11,
Further comprising a failure alarm notifying a failure occurrence to the outside when a failure occurs in the cell balancing switch,
(c) notifying the failure occurrence of the cell balancing switch visually or audibly through the failure alarm.

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