Battery monitoring device

Abstract

To provide a battery monitoring device capable of preventing destruction of a cell balance switch element during hot-line insertion / removal.SOLUTION: A battery monitoring device includes: a plurality of contacts connected to each of an electrode terminal of both ends of series connection of a plurality of battery cells and an electrode terminal of adjacent battery cells among the plurality of battery cells: and a plurality of MOS transistors provided as a plurality of cell balance switch elements respectively corresponding to the plurality of battery cells, the plurality of MOS transistors being connected in series to each other by being connected to the contacts via a resistor so as to be respectively connected to both electrode terminals of each of the battery cells. A low-potential-side MOS transistor corresponding to the battery cell of a low-potential portion is composed of an N-channel MOS transistor. A high-potential-side MOS transistor corresponding to the battery cell of a high-potential portion includes a P-channel MOS transistor. At least one of the low-potential-side MOS transistor and the high-potential-side MOS transistor has a high breakdown voltage.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a battery monitoring device that adjusts the voltage of each of a plurality of battery cells connected in series. [Background technology]

[0002] In a battery pack having multiple battery cells connected in series, there is variation in cell voltage due to individual differences in characteristics such as capacity of each battery cell. The variation in cell voltage not only leads to overcharging and over-discharging, but also has the risk of accelerating the deterioration of the battery cells themselves. In order to eliminate such variation in cell voltage, there is a battery monitoring device that balances the cell voltage of each battery cell.

[0003] In a conventional battery monitoring device, as disclosed in Patent Document 1, a series circuit of a resistor and a cell balance switch element is provided between the positive and negative terminals of each battery cell. The cell voltage of each battery cell is monitored by a control circuit. For example, when the cell voltage of any one of the multiple battery cells becomes higher than a predetermined upper limit voltage or the voltage difference between the cell voltage of the one battery cell and the other battery cells becomes larger than a specified voltage, the control circuit turns on the cell balance switch element corresponding to the one battery cell and causes a discharge current to flow from the one battery cell through the resistor and the cell balance switch element, thereby discharging the charge of the one battery cell. In this way, the cell voltage of each of the multiple battery cells is adjusted so that the cell voltage is within the upper limit voltage. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-253777 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, a battery pack having multiple battery cells and a battery monitoring device are connected via a connector (for example, a plug and receptacle). A plurality of contacts are provided on each of the battery pack side and the battery monitoring device side of the connector so as to correspond to each other. When the connectors are coupled, all of the contacts on both sides of the connector are not connected at the same time, but are connected in a random order. For this reason, when a live insertion / removal (hot plug) is performed, which is the coupling of the connectors while each of the multiple battery cells is in a charged state, there is a problem that the random connection of the contacts described above may exceed the withstand voltage of the MOS transistor, which is the cell balance switch element, depending on the order in which the contacts are connected, and the cell balance switch element may be destroyed due to the exceeded withstand voltage.

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a battery monitoring device that can prevent damage to cell balance switch elements during hot swapping. [Means for solving the problem]

[0007] A battery monitoring device of the present invention is connected via a connector to a battery device consisting of a plurality of battery cells connected in series, and adjusts the voltage of each of the plurality of battery cells, the battery monitoring device comprising: a plurality of contacts provided within the connector, each of which is connected to electrode terminals at both ends of the series connection of the plurality of battery cells and to electrode terminals of adjacent battery cells among the plurality of battery cells when the battery device is connected to the battery monitoring device via the connector; and a plurality of MOS transistors provided as a plurality of cell balance switch elements corresponding to each of the plurality of battery cells, each of which is connected in series to the contacts via a resistor so as to be connected to both electrode terminals of each of the plurality of battery cells, the low potential side MOS transistor corresponding to a battery cell in a low potential portion of the plurality of battery cells being comprised of an N channel MOS transistor, and a high potential side MOS transistor corresponding to a battery cell in a high potential portion of the plurality of battery cells being comprised of a P channel MOS transistor, and at least one of the low potential side MOS transistor and the high potential side MOS transistor being a high voltage transistor. Effect of the Invention

[0008] According to the battery monitoring device of the present invention, high-voltage MOS transistors are used as cell balancing switch elements to which high voltages may be applied from battery cells during live insertion / removal, so that the cell balancing switch elements can be prevented from being destroyed during live insertion / removal. [Brief description of the drawings]

[0009] [Figure 1] 1 is a circuit diagram showing a battery monitoring device according to a first embodiment of the present invention. [Diagram 2] FIG. 5 is a circuit diagram showing a battery monitoring device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. EXAMPLES

[0011] 1 shows a battery monitoring device 10 as a first embodiment of the present invention. This battery monitoring device 10 of the present invention is connected to a battery pack BP (battery device) consisting of 17 battery cells BC1 to BC17 via a connector 11. Each of the battery cells BC1 to BC17 is composed of a lithium ion battery, and each battery cell can have a voltage of about 3.6 V when in a charged resting state.

[0012] The battery cells BC1 to BC17 of the battery pack BP are connected in series in that order: the negative terminal (electrode terminal) of the battery cell BC1 is connected to ground GND, the negative terminal of the battery cell BC2 is connected to the positive terminal (electrode terminal) of the battery cell BC1, the negative terminal of the battery cell BC3 is connected to the positive terminal of the battery cell BC2, ..., the negative terminal of the battery cell BC17 is connected to the positive terminal of the battery cell BC16.

[0013] In FIG. 1, the connector 11 is shown as one unit made up of multiple switches, but it has a two-piece structure. The battery pack BP side of the connector 11 is, for example, a plug, and the battery monitoring device 10 side is, for example, a receptacle. The contacts on the battery pack BP side of the connector 11 are PC0 to PC17, and the contacts on the battery monitoring device 10 side are MC0 to MC17. The contacts PC0 to PC17 and the contacts MC0 to MC17 correspond to each other, and are in a pair relationship with the same numbers. That is, pair (PC0, MC0), pair (PC1, MC1), pair (PC2, MC2), ..., pair (PC17, MC17). When the connector 11 is mated, the paired contacts are connected to each other and are turned on as a switch.

[0014] In addition, in the battery pack BP, the negative terminal of battery cell BC1 is connected to contact PC0, the positive terminal of battery cell BC1 and the negative terminal of battery cell BC2 are connected to contact PC1, the positive terminal of battery cell BC2 and the negative terminal of battery cell BC3 are connected to contact PC2, ..., the positive terminal of battery cell BC16 and the negative terminal of battery cell BC17 are connected to contact PC16, and the positive terminal of battery cell BC17 is connected to contact PC17.

[0015] The battery monitoring device 10 includes resistors R0 to R17, capacitors C0 to C17, terminals VT0 to VT17, MOS transistors MT1 to MT17, and a control circuit 12. The resistors R0 to R17, capacitors C0 to C17, and terminals VT0 to VT17 are provided corresponding to contacts MC0 to MC17 of the connector 11. The resistance values ​​of the resistors R0 to R17 are, for example, 10 [Ω] to 1 [kΩ], and the capacitances of the capacitors C0 to C17 are, for example, 0.1 [μF] to 2 [μF].

[0016] One end of the resistors R0 to R17 is connected to the corresponding contacts MC0 to MC17, and the other end of the resistors R0 to R17 is connected to one end of the capacitors C0 to C17. The capacitors C0 to C17 are connected in series. That is, the other end of the capacitor C0 is connected to the ground GND, the other end of the capacitor C1 is connected to one end of the capacitor C0, ..., the other end of the capacitor C17 is connected to one end of the capacitor C16.

[0017] Moreover, one end of the capacitors C0 to C17 is connected to the terminals VT0 to VT17. The terminals VT0 to VT17 are terminals of an IC (integrated circuit). The MOS transistors MT1 to MT17 and the control circuit 12 are formed within the IC. Each of the MOS transistors MT1 to MT17 functions as a cell balance switch element.

[0018] The MOS transistors MT1 and MT2 (MOS transistors on the low potential side) corresponding to the battery cells BC1 and BC2 arranged in the low potential portion of the voltage level of the battery pack BP are N-channel MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). The MOS transistors MT3 to MT15 (MOS transistors on the medium potential side) corresponding to the battery cells BC3 to BC15 arranged in the medium potential portion of the voltage level of the battery pack BP and the MOS transistors MT16 and MT17 (MOS transistors on the high potential side) corresponding to the battery cells BC16 and BC17 arranged in the high potential portion are P-channel MOSFETs. This is to ensure a sufficient gate-source voltage for the MOS transistors MT1 to MT17. Note that the MOS transistors MT3 to MT15 arranged in correspondence with the medium potential portion can be N-channel MOSFETs instead of P-channel MOSFETs.

[0019] The MOS transistors MT1 to MT17 are connected in series between the terminals VT0 and VT17. Specifically, the source of the N-channel MOS transistor MT1 is connected to the terminal VT0, and the drain of the MOS transistor MT1 is connected to the terminal VT1 together with the source of the MOS transistor MT2. The drain of the MOS transistor MT2 is connected to the terminal VT2.

[0020] The drain of the P-channel MOS transistor MT3 is connected to the terminal VT2, the source of the MOS transistor MT3 and the drain of the MOS transistor MT4 are connected to the terminal VT3, ..., the source of the MOS transistor MT16 and the drain of the MOS transistor MT17 are connected to the terminal VT16, and the source of the MOS transistor MT17 is connected to the terminal VT17.

[0021] The gates of the MOS transistors MT1 to MT17 are connected to the control circuit 12. The control circuit 12 is also connected to the terminals VT0 to VT17 and receives the voltages of the terminals VT0 to VT17, respectively.

[0022] The control circuit 12 obtains the voltage difference between adjacent terminals among the terminals VT0 to VT17 as the voltage between the positive and negative terminals of the battery cells BC1 to BC17. When any voltage difference exceeds the upper limit voltage due to charging of the battery cells BC1 to BC17, the control circuit 12 supplies a control signal to the gate of the corresponding MOS transistor among the MOS transistors MT1 to MT17 to turn on that MOS transistor. For example, when the voltage difference between the terminals VT17 and VT16, which represent the voltage between the positive and negative terminals of the battery cell BC17, exceeds the upper limit voltage, the control circuit 12 supplies a control signal to the gate of the MOS transistor MT17 to turn on the MOS transistor MT17 and discharge the charge of the battery cell BC17. In addition, when the voltage difference between the terminals VT17 and VT16 drops to a specified voltage lower than the upper limit voltage, the control circuit 12 turns off the MOS transistor MT17. The on / off control of the MOS transistor MT17 by the control circuit 12 is similar to that of the other MOS transistors MT1 to MT16.

[0023] In the battery monitoring device 10 of the present invention having such a configuration, of the MOS transistors MT1 to MT17 which are the cell balance switch elements, the P-channel MOS transistors MT3 to MT17 are low-voltage transistors (low-voltage Tr), while the N-channel MOS transistors MT1 and MT2 (MOS transistors on the low potential side) are high-voltage transistors (high-voltage Tr).

[0024] When the gate-source capacitance of the N-channel MOS transistors MT1, MT2 is larger than the gate-source capacitance of the P-channel MOS transistors MT3 to MT17, the N-channel MOS transistors MT1, MT2 are each made to have a high withstand voltage. The withstand voltage of each N-channel MOS transistor MT1, MT2 is set to be more than twice the withstand voltage of the P-channel MOS transistors MT3 to MT17. For example, while the withstand voltage of the source-drain voltage of the P-channel MOS transistors MT3 to MT17 is 7 to 10 V, the withstand voltage of the drain-source voltage of each N-channel MOS transistor MT1, MT2 is 20 V.

[0025] In this way, high-voltage transistors are used for the N-channel MOS transistors MT1 and MT2, so that it is possible to prevent destruction of the MOS transistors MT1 and MT2 when the battery pack BP and the battery monitoring device 10 are connected via the connector 11 while the battery cells BC1 to BC17 of the battery pack BP are charged.

[0026] Specifically, when the battery pack BP and the battery monitoring device 10 are connected by the connector 11, the contacts PC0 to PC17 of the connector 11 and the corresponding contacts MC0 to MC17 are not all connected at the same time. The order of connection is random.

[0027] For example, suppose that after the contacts PC0 and MC0 are connected, the contacts PC17 and MC17 are connected while the contacts PC1 to PC16 and the corresponding contacts MC1 to MC16 are not connected. In this case, if the gate-source capacitance of the N-channel MOS transistors MT1 and MT2 is larger than the gate-source capacitance of the P-channel MOS transistors MT3 to MT17, the P-channel MOS transistors MT3 to MT17 are turned on and the N-channel MOS transistors MT1 and MT2 are turned off at the moment that the contacts PC17 and MC17 are connected. The voltage of the terminal VT17 is applied to the MOS transistors MT1 and MT2 in the off state through the P-channel MOS transistors MT3 to MT17 in the on state. At this time, even if the voltage applied between the drain and source of each of the N-channel MOS transistors MT1 and MT2 exceeds, for example, 10 [V], the N-channel MOS transistors MT1 and MT2 can be prevented from being destroyed because the N-channel MOS transistors MT1 and MT2 have a high withstand voltage.

[0028] In the above-described first embodiment, the MOS transistors MT3 to MT17 among the MOS transistors MT1 to MT17 are P-channel MOS transistors, and the two MOS transistors MT1 and MT2 on the lower potential side of the transistors MT3 to MT17 are N-channel MOS transistors. However, the number of MOS transistors on the lower potential side is not limited to two, and may be, for example, about one to three.

[0029] In addition, in the above-described first embodiment, the P-channel MOS transistors MT3 to MT17 among the MOS transistors MT1 to MT17 may be low-voltage transistors, which has the advantage that the chip size does not become large when the battery monitoring device 10 is implemented as an LSI.

[0030] In the high-voltage MOS transistor used in the first embodiment, the depletion layer is easily expanded in order to ensure the breakdown voltage. - The drift layer is thickened and N - The impurity concentration of the drift layer is reduced.

[0031] In addition, in the battery monitoring device 10 of the above-mentioned Example 1, of the MOS transistors MT1 to MT17 which are the cell balance switch elements, the P-channel MOS transistors MT3 to MT17 are low voltage transistors, while the N-channel MOS transistors MT1, MT2 are high voltage transistors. However, when the gate-source capacitance of the P-channel MOS transistors MT16, MT17 is larger than the gate-source capacitance of the N-channel MOS transistors MT1 to MT15, each of the P-channel MOS transistors MT16, MT17 is considered to be a high voltage MOS transistor. In this manner, when each of the P-channel MOS transistors MT16, MT17 is a high-voltage MOS transistor, for example, when contacts PC17 and MC17 are connected and then contacts PC0 and MC0 are connected while contacts PC1 to PC16 and corresponding contacts MC1 to MC16 are not connected, even if the voltage applied between the source and drain of each of the P-channel MOS transistors MT16, MT17 which remain in the off state exceeds, for example, 10 V, the P-channel MOS transistors MT16, MT17 can be prevented from being destroyed because they have a high voltage resistance. EXAMPLES

[0032] 2 shows a battery monitoring device 20 as a second embodiment of the present invention. Similar to the battery monitoring device 10 of the first embodiment, the battery monitoring device 20 of the present invention is connected via a connector 11 to a battery pack BP consisting of 17 battery cells BC1 to BC17.

[0033] Similarly to the battery monitoring device 10 of the first embodiment, the battery monitoring device 20 includes resistors R0-R17, capacitors C0-C17, terminals VT0-VT17, MOS transistors MT1-MT17, and a control circuit 12. The connections of the resistors R0-R17, capacitors C0-C17, terminals VT0-VT17, MOS transistors MT1-MT17, and control circuit 12 are the same as those of the battery monitoring device 10, so a description thereof will be omitted here.

[0034] As for the MOS transistors MT1 to MT17 which are cell balance switch elements, the MOS transistors MT1 and MT2 on the low potential side of the voltage level of the battery pack BP are N-channel MOSFETs, and the MOS transistors MT3 to MT17 on the high potential and intermediate potential sides are P-channel MOSFETs.

[0035] In the battery monitoring device 20 of the present invention having such a configuration, among the MOS transistors MT1 to MT17, the P-channel MOS transistors MT3 to MT15 are low-voltage transistors (low-voltage Tr), while the N-channel MOS transistors MT1, MT2 and the P-channel MOS transistors MT16, MT17 are high-voltage transistors (high-voltage Tr).

[0036] That is, the withstand voltages of the N-channel MOS transistors MT1, MT2 and the P-channel MOS transistors MT16, MT17 located at the ends of the MOS transistors MT1 to MT17 connected in series are set higher than the withstand voltages of the P-channel MOS transistors MT3 to MT15 located between them. The withstand voltages of the N-channel MOS transistors MT1, MT2 and the P-channel MOS transistors MT16, MT17 are set to be at least twice the withstand voltages of the P-channel MOS transistors MT3 to MT15. For example, while the withstand voltage of the source-drain voltage of the P-channel MOS transistors MT3 to MT15 is 7 to 10 [V], the withstand voltage of the drain-source voltage of each of the N-channel MOS transistors MT1, MT2 and the withstand voltage of the source-drain voltage of each of the P-channel MOS transistors MT16, MT17 is 20 [V].

[0037] In this way, high-voltage transistors are used for the N-channel MOS transistors MT1, MT2 and the P-channel MOS transistors MT16, MT17. Therefore, when the battery pack BP and the battery monitoring device 10 are connected via the connector 11 while the battery cells BC1 to BC17 of the battery pack BP are charged, the voltage waveform at the terminal farthest from the connection terminal becomes dull due to the influence of parasitic resistance and parasitic capacitance, and the MOS transistors MT1, MT2 or MT16, MT17 are in the off state, and destruction of those MOS transistors can be prevented.

[0038] Specifically, when the battery pack BP and the battery monitoring device 20 are connected by the connector 11, the contacts PC0 to PC17 of the connector 11 and the corresponding contacts MC0 to MC17 are not all connected at the same time. The order of connection is random.

[0039] This causes the waveform at the terminal far from the terminal (any one of terminals VT0 to VT17) of the battery monitoring device 20 corresponding to the connection contact of the connector 11 to become dull, and the gate-source voltage of the MOS transistor does not become large. If this happens, the MOS transistors MT1, MT2 or MT16, MT17 connected to the far terminal will not be turned on, and a large voltage will be applied between the drain-source of the MOS transistors MT1, MT2 or between the source-drain of MT16, MT17. However, because these MOS transistors are high-voltage transistors, the withstand voltage will not be exceeded and they will not be destroyed.

[0040] For example, if contacts PC0 and MC0 are connected together while contacts PC0-PC16 and MC0-MC16 are not connected after contacts PC17 and MC17 of connector 11 are connected together, MOS transistors close to terminal VT0, such as MOS transistors MT1, MT2, and MT3, turn on, but the voltage waveforms of terminals VT15 and VT16 far from terminal VT0 become rounded due to the influence of parasitic resistance and parasitic capacitance, and MOS transistors MT16 and MT17 do not turn on. As a result, the source-drain voltage of MOS transistors MT16 and MT17 increases, but because MOS transistors MT16 and MT17 are high-voltage transistors, destruction of MOS transistors MT16 and MT17 can be prevented.

[0041] Conversely, if contacts PC17 and MC17 are connected together while contacts PC1-PC17 and MC1-MC17 are not connected after contacts PC0 and MC0 of connector 11 are connected together, MOS transistors close to terminal VT17, such as MOS transistors MT17, MT16, and MT15, turn on, but the voltage waveforms of terminals VT1 and VT0 far from terminal VT17 become rounded due to the influence of parasitic resistance and parasitic capacitance, and MOS transistors MT2 and MT1 do not turn on. This causes the drain-source voltages of MOS transistors MT2 and MT1 to increase, but because MOS transistors MT2 and MT1 are high-voltage transistors, destruction of MOS transistors MT2 and MT1 can be prevented.

[0042] In the above-described second embodiment, the MOS transistors MT3 to MT15 can remain low-voltage transistors, which has the advantage that the chip size does not increase when the battery monitoring device 20 is implemented as an LSI. [Explanation of symbols]

[0043] 10 Battery monitoring device 11 Connectors 12 Control circuit BP Battery Pack BC1~BC17 Battery cells C1~C17 Capacitors GND Ground MC0~MC17, PC0~PC17 contacts MT1~MT17 MOS transistors R1~R17 Resistors VT0 to VT17 terminals

Claims

1. A battery monitoring device that is connected via a connector to a battery device that is made up of a plurality of battery cells connected in series and adjusts the voltage of each of the plurality of battery cells, a plurality of contacts provided within the connector, the contacts being connected to electrode terminals at both ends of the series connection of the plurality of battery cells and to electrode terminals of adjacent battery cells among the plurality of battery cells when the battery device is connected to the battery monitoring device via the connector; a plurality of MOS transistors provided as a plurality of cell balance switch elements respectively corresponding to the plurality of battery cells, the MOS transistors being connected in series to each other by being connected to the contacts via resistors so that each of the MOS transistors is connected to both electrode terminals of each of the plurality of battery cells; a low-potential side MOS transistor corresponding to a low-potential portion of the battery cells among the plurality of battery cells is an N-channel MOS transistor; a high-potential side MOS transistor corresponding to a high-potential portion of the battery cells among the plurality of battery cells is a P-channel MOS transistor; At least one of the low potential side MOS transistor and the high potential side MOS transistor is a high voltage transistor.

2. When the gate-source capacitance of the N-channel MOS transistor is larger than the gate-source capacitance of the P-channel MOS transistor, the MOS transistor on the low potential side is a high voltage transistor, 2. A battery monitoring device according to claim 1, wherein when the gate-source capacitance of said P-channel MOS transistor is larger than the gate-source capacitance of said N-channel MOS transistor, said MOS transistor on the high potential side is a high voltage transistor.

3. 2. The battery monitoring device according to claim 1, wherein at least one of the low potential side MOS transistor and the high potential side MOS transistor has a withstand voltage higher than a withstand voltage of a medium potential side MOS transistor corresponding to a battery cell in a medium potential portion other than the low potential portion and the high potential portion among the plurality of battery cells.

4. 4. The battery monitoring device according to claim 3, wherein at least one of the low potential side MOS transistor and the high potential side MOS transistor has a withstand voltage at least twice as high as that of the intermediate potential side MOS transistor.

5. 5. A battery monitoring device according to claim 3, wherein the MOS transistor on the intermediate potential side is an N-channel MOS transistor or a P-channel MOS transistor.

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