AC generating circuit and AC generating device

Abstract

This invention provides an AC generating circuit and an AC generating device capable of uniformly raising the temperature of multiple series-connected secondary batteries and reducing losses caused by resistance. The AC generating circuit includes multiple sub-circuits connected to the positive and negative terminals of each of the series-connected secondary batteries. In each of the multiple sub-circuits, the negative terminal of one sub-circuit is connected to the positive terminal of another sub-circuit via a first intermediate connection point. The first intermediate connection point is connected to a second intermediate connection point, which connects the negative terminal of one of the two adjacent secondary batteries to the positive terminal of another. A capacitor is provided at least in a portion of the locations between one or more of the first and second intermediate connection points.

Description

Technical Field

[0001] This invention relates to AC generating circuits and AC generating devices. Background Technology

[0002] To mitigate the adverse environmental impacts on Earth (e.g., to reduce NOx, SOx, and CO2), the use of electric vehicles powered by electricity stored in secondary batteries is increasingly prevalent. It is known that the charge-discharge characteristics of a secondary battery decrease when its temperature drops below a suitable range. Relatedly, an invention has been disclosed that, in order to efficiently raise the temperature of a secondary battery when its temperature is low, is a secondary battery heating device that effectively heats the secondary battery from within, thereby enabling efficient temperature rise. (Patent Document 1)

[0003] Prior technology literature

[0004] [Patent Documents]

[0005] Patent Document 1: International Publication No. 2011 / 004464 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] Therefore, when high voltage is required, multiple secondary batteries are sometimes connected in series to form a power source. In the technology described in Patent Document 1, when multiple batteries are connected in series, the voltage of each battery varies, which sometimes causes variations in the temperature rise of the batteries.

[0008] The present invention was made in consideration of such circumstances, and one of its objectives is to provide an AC generating circuit and AC generating device that can improve energy efficiency by making the temperature of multiple series-connected secondary batteries rise uniformly and reducing losses caused by resistance.

[0009] Solution for solving the problem

[0010] The AC generating circuit and AC generating device of the present invention adopt the following structure.

[0011] (1): An AC generating circuit of one aspect of the present invention includes multiple sub-circuits connected to the positive and negative terminals of multiple secondary batteries connected in series. In the multiple sub-circuits, the negative terminal side of one sub-circuit of two adjacent sub-circuits is connected to the positive terminal side of another sub-circuit through a first intermediate connection point. The first intermediate connection point is connected to a second intermediate connection point, which connects the negative terminal of one secondary battery to the positive terminal of another secondary battery in two adjacent secondary batteries. At least a portion of the locations between one or more first intermediate connection points and second intermediate connection points are provided with capacitors.

[0012] (2): Based on the above (1) scheme, a capacitor is provided at each of the positions where multiple first intermediate connection points are connected to multiple second intermediate connection points.

[0013] (3): Based on the above (1) scheme, a capacitor is provided at a portion of the positions where the plurality of first intermediate connection points are connected to the plurality of second intermediate connection points, and a current limiting element is provided at a portion or all of the positions where the capacitor is not provided in the positions where the plurality of first intermediate connection points are connected to the plurality of second intermediate connection points.

[0014] (4): Based on the above (1) scheme, the sub-circuit includes multiple sub-circuit capacitors, and AC is generated by switching the connection relationship of the sub-circuit capacitors to be connected in series / parallel relative to the corresponding secondary battery.

[0015] (5): Based on the above (1) scheme, the capacitor disposed between the first intermediate connection point and the second intermediate connection point is connected to the branch busbar constituting the first intermediate connection point or connected to the first intermediate connection point via the first connecting piece, and is connected to the busbar constituting the second intermediate connection point via the second connecting piece. The capacitor, the first connecting piece and the second connecting piece are a structure covered by an insulating member, such as being sealed by a resin molding part. The branch busbar and at least a portion of the busbar are exposed outside the part covered by the insulating member.

[0016] (6): Another aspect of the present invention provides an AC generating device comprising: the AC generating circuit of the above-described (1) aspect; and a control unit that causes a portion or all of the plurality of sub-circuits to generate AC power with different phases.

[0017] Invention Effects

[0018] According to the schemes (1) to (6) above, by making the temperature of multiple secondary batteries connected in series rise uniformly and reducing the loss caused by resistance, it is possible to improve energy efficiency.

[0019] According to the above scheme (3), the safety of the circuit can be improved by making the temperature of multiple secondary batteries rise uniformly and increasing the number of fuses.

[0020] According to the above scheme (5), the branch busbar is insulated from the battery module in DC direction, so it will not become a live part. When assembling the battery package, there is no need to take measures to prevent short circuits on the exposed part of the branch busbar. Attached Figure Description

[0021] Figure 1 This is a diagram illustrating an example of the structure of the AC generating device 1 and the AC generating circuit 10 according to the first embodiment.

[0022] Figure 2 This diagram illustrates an example of the changes in voltage and current generated in the AC generating circuit 10 due to the switching on / off of the sub-circuit in the first embodiment.

[0023] Figure 3 This is a diagram illustrating an example of the structure of the AC generation circuit in a comparative example of the first embodiment.

[0024] Figure 4 This is a diagram illustrating an example of the changes in voltage and current generated in the AC generating circuit 10 by switching on / off the sub-circuit in a comparative example of the first embodiment.

[0025] Figure 5 This is a diagram illustrating an example of the structure of the AC generating device 1A and the AC generating circuit 10A according to the second embodiment.

[0026] Figure 6 This diagram illustrates an example of the changes in voltage and current generated in the AC generating circuit 10A due to the switching on / off of the sub-circuit in the second embodiment.

[0027] Figure 7 This is a diagram illustrating an example of the structure of the AC generation circuit in a comparative example of the second embodiment.

[0028] Figure 8 This is a diagram illustrating an example of the changes in voltage and current generated in the AC generating circuit 10A due to the switching on / off of the sub-circuit in a comparative example of the second embodiment.

[0029] Figure 9 This is a diagram illustrating an example of the structure of the AC generating device 1B and the AC generating circuit 10B according to the third embodiment.

[0030] Figure 10 This is a diagram illustrating an example of the structure of the AC generating device 1C and the AC generating circuit 10C of a modified example 1 of the third embodiment.

[0031] Figure 11 This is a diagram illustrating an example of the structure of the AC generating device 1D and the AC generating circuit 10D of a modified embodiment 2 of the third embodiment.

[0032] Figure 12 This diagram illustrates an example of the configuration of a capacitor placed between the first intermediate connection point and the second intermediate connection point.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. AC generating device

[0035] 10. AC Generating Circuit

[0036] 10-1 First Sub-circuit

[0037] 10-2 Second Sub-circuit

[0038] 100 Control Department

[0039] 200 battery module

[0040] 210 Busbar

[0041] 220-1 First Connecting Piece

[0042] 220-2 Second Connecting Piece

[0043] 230 branch busbars

[0044] 240 capacitor

[0045] 250 Resin Mold

[0046] Q1 First intermediate connection point

[0047] Q2 Second intermediate connection point

[0048] B1 First and Secondary Batteries

[0049] B2 Secondary Battery

[0050] C100 capacitor

[0051] F. Fuse. Detailed Implementation

[0052] Hereinafter, embodiments of the AC generating circuit and AC generating device of the present invention will be described with reference to the accompanying drawings. The AC generating circuit and AC generating device are installed in a secondary battery and heat the secondary battery when needed. In particular, the AC generating circuit of the present invention can heat each secondary battery in a structure in which multiple secondary batteries are connected in series.

[0053] <First Implementation Method>

[0054] Figure 1 This diagram illustrates an example of the structure of the AC generating device 1 and AC generating circuit 10 according to the first embodiment. In this embodiment, the secondary battery and the AC generating circuit are each provided in two sections. That is, the secondary battery includes a first secondary battery B1 and a second secondary battery B2 connected in series. The AC generating circuit 10 includes a first sub-circuit 10-1 corresponding to the first secondary battery B1 and a second sub-circuit 10-2 corresponding to the second secondary battery B2. The positive terminal of the first secondary battery B1 is connected to the negative terminal of the second secondary battery B2. The positive terminal side of the first sub-circuit 10-1 is connected to the positive terminal of the first secondary battery B1, and the negative terminal side of the first sub-circuit 10-1 is connected to the negative terminal of the first secondary battery B1. The positive terminal side of the second sub-circuit 10-2 is connected to the positive terminal of the second secondary battery B2, and the negative terminal side of the second sub-circuit 10-2 is connected to the negative terminal of the second secondary battery B2. Furthermore, the AC generating circuit 10 includes a fuse F and a capacitor C100. Moreover, the AC generating device 1 includes the AC generating circuit 10 and a control unit 100.

[0055] exist Figure 1 In this context, the characteristics of the first and second-generation batteries B1 are hypothetically represented as the energy storage unit E1 and the resistor R. S and inductor L S Furthermore, the characteristics of the second secondary battery B2 are hypothetically represented by the energy storage unit E1 and the resistance R. S and inductor L S .

[0056] The first secondary battery B1 and the second secondary battery B2 are, for example, lithium-ion batteries or other batteries capable of repeated charging and discharging. The first secondary battery B1 and the second secondary battery B2 can each be a single battery or a battery consisting of multiple battery cells connected in series or parallel. It should be noted that the power supplied by the first secondary battery B1 and the second secondary battery B2 can also be supplied to the load via a DC-AC converter, DC-DC converter, or other means not shown in the diagram.

[0057] The positive contact P1 of the first sub-circuit 10-1 is connected to the first intermediate connection point Q1. The negative contact P2 of the first sub-circuit 10-1 is connected to the negative contact P5, which serves as the negative terminal of the first secondary battery B1. Capacitors C1 and C2, and switches S1 to S3 are provided between contacts P1 and P2 to generate AC current. This structure corresponds to the first sub-circuit 10-1.

[0058] In the first sub-circuit 10-1, there is a first path connecting capacitor C1 and switch S1 in series, and a second path connecting switch S2 and capacitor C2 in series, connected in parallel between contacts P1 and P2. Contact P3, located between capacitor C1 and switch S1, and contact P4, located between switch S2 and capacitor C2, are connected via a third path. Switch S3 is provided in the third path.

[0059] The positive contact P6 of the second sub-circuit 10-2 is connected to the positive terminal of the second secondary battery B2 via a fuse F. The negative contact P7 of the second sub-circuit 10-2 is connected to the first intermediate connection point Q1. Capacitors C4 and C5, and switches S4 to S6 are provided between contacts P6 and P7 to generate AC current. This structure corresponds to the second sub-circuit 10-2.

[0060] In the second sub-circuit 10-2, a first path connecting capacitor C4 and switch S4 in series, and a second path connecting switch S5 and capacitor C5 in series, exist in parallel between contacts P6 and P7. Contact P8, located between capacitor C4 and switch S4, and contact P9, located between switch S5 and capacitor C5, are connected via a third path. Switch S6 is located in the third path. It should be noted that a second intermediate connection point Q2 is provided between the positive terminal of the first secondary battery B1 and the negative terminal of the second secondary battery B2.

[0061] Fuse F is located between contacts P6 and P10. When the current flowing through fuse F exceeds a certain limit, fuse F melts and interrupts the current flow. It should be noted that fuse F is an example of a "current limiting element." For example, other current limiting elements such as PTC (Positive Temperature Coefficient) thermistors can also be used.

[0062] Capacitor C100 is disposed between the first intermediate connection point Q1 and the second intermediate connection point Q2. Capacitor C100 selectively allows the AC component flowing between the first intermediate connection point Q1 and the second intermediate connection point Q2 to pass through, while suppressing the passage of the DC component.

[0063] The control unit 100 is implemented, for example, by a CPU (Central Processing Unit), LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), or IC (Integrated Circuit). The control unit 100 generates AC current in the first sub-circuit 10-1 and the second sub-circuit 10-2 by controlling the switches S1 to S6 included in the first sub-circuit 10-1 and the second sub-circuit 10-2 to be turned on / off, respectively. It should be noted that in this embodiment, capacitors C1, C2, C4, and C5 are examples of sub-circuit capacitors, and their capacitances are set to be the same. The capacitance of capacitor C100 can be the same as or different from them. Furthermore, the control unit 100 can also generate AC current with different phases in the first sub-circuit 10-1 and the second sub-circuit 10-2 by making the control phases of the switches in each sub-circuit different.

[0064] In the first sub-circuit 10-1, the control unit 100, for example, switches S1, S2, and S3 to switch capacitors C1 and C2 in series / parallel with respect to the first secondary battery B1. The control unit 100 connects capacitors C1 and C2 in parallel with respect to the first secondary battery B1 by turning on switches S1 and S2 and turning off switch S3, and connects capacitors C1 and C2 in series with respect to the first secondary battery B1 by turning off switches S1 and S2 and turning on switch S3.

[0065] When capacitors C1 and C2 are connected in parallel with respect to the first secondary battery B1, the voltages of each capacitor are close to the voltage of the first secondary battery B1 (the capacitors are charging). Conversely, when capacitors C1 and C2 are connected in series with respect to the first secondary battery B1, the voltages of each capacitor are close to half the voltage of the first secondary battery B1 (the capacitors are discharging). This process is repeated to generate alternating current between the first sub-circuit 10-1 and the first secondary battery B1. The control unit 100 controls switches S1, S2, and S3 in this manner.

[0066] In the second sub-circuit 10-2, the control unit 100, for example, switches S4, S5, and S6 to switch capacitors C4 and C5 in series / parallel with respect to the second secondary battery B2. The control unit 100 connects capacitors C4 and C5 in parallel with respect to the second secondary battery B2 by turning on switches S4 and S5 and turning off switch S6, and connects capacitors C4 and C5 in series with respect to the second secondary battery B2 by turning off switches S4 and S5 and turning on switch S6.

[0067] When capacitors C4 and C5 are connected in parallel with respect to the second secondary battery B2, the voltages of each capacitor C4 and C5 are close to the voltage of the second secondary battery B2 (the capacitors are charged). Conversely, when capacitors C4 and C5 are connected in series with respect to the second secondary battery B2, the voltages of each capacitor C4 and C5 are close to half the voltage of the second secondary battery B2 (the capacitors are discharged). This process is repeated to generate alternating current between the second sub-circuit 10-2 and the second secondary battery B2. The control unit 100 controls switches S4, S5, and S6 in this manner.

[0068] Figure 2 This diagram illustrates an example of the changes in voltage and current generated in the AC generating circuit 10 due to the switching on / off of the sub-circuit in the first embodiment. The changes shown in this diagram are the results of simulations performed by the inventors of this application. As shown, in the first sub-circuit 10-1, at time t1, capacitors C1 and C2 are connected in series with respect to the first secondary battery B1. Before time t1, the sum of the voltages of capacitors C1 and C2 is greater than the voltage of the first secondary battery B1, therefore, when time t1 arrives, the voltage V1-V0 rises significantly. Afterwards, during the period up to time t2, capacitors C1 and C2 discharge respectively, and the discharged power is used to charge the first secondary battery B1. As time approaches t2, due to the inductance L... S With the presence of [a certain condition], the current I_E1 is maintained in the direction of flowing from capacitors C1 and C2 to the first secondary battery B1, respectively, thus the voltage V1-V0 decreases to its lower limit. From time t2 to time t5, capacitors C1 and C2 are connected in parallel with respect to the first secondary battery B1, so their voltages are close to the voltage of the first secondary battery B1.

[0069] In the second sub-circuit 10-2, at time t3, capacitors C4 and C5 are connected in series with respect to the second secondary battery B2. Before time t3, the sum of the voltages of capacitors C4 and C5 is greater than the voltage of the second secondary battery B2, therefore, at time t3, the voltage V2-V1 rises significantly. Afterwards, during the period up to time t4, capacitors C4 and C5 discharge separately, using the discharged power to charge the second secondary battery B2. As time approaches t4, due to the inductance L... S With the presence of [a certain condition], the current I_E2 is maintained in the direction from capacitors C4 and C5 to the second secondary battery B2, respectively, thus the voltage V2-V1 decreases to its lower limit. From time t4 to time t6, capacitors C4 and C5 are connected in parallel with respect to the second secondary battery B2, therefore their voltages are close to the voltage of the second secondary battery B2.

[0070] Furthermore, because capacitor C100 is provided, a certain degree of alternating current can pass between the first intermediate connection point Q1 and the second intermediate connection point Q2 while suppressing the rapid current flow due to short circuits, etc. Therefore, even when the voltages of the first secondary battery B1 and the second secondary battery B2 are different at the time when the AC generating device 1 starts operating, AC is generated in a way that cancels out the difference in AC energy, and the amplitudes of the currents I_E1 and I_E2 flowing through them become uniform. Moreover, compared with the comparative example described later, since no fuse is provided near the first intermediate connection point Q1 and the second intermediate connection point Q2, losses caused by resistance can be reduced.

[0071] [Comparison with comparative examples]

[0072] Here, a comparison with the first embodiment is explained. Figure 3 This is a diagram illustrating an example of the structure of the AC generation circuit in a comparative example of the first embodiment. Figure 3 In this drawing, components having the same function as those in the first embodiment described above are labeled with the same reference numerals. The AC generation circuit of the comparative example is as follows: Figure 3 As shown, no capacitor C100 is provided, and a fuse F1 is provided between contact P1 and the positive terminal of the first secondary battery B1. In this case, the loss caused by the resistance of the fuse F1 becomes larger. In addition, since there is no capacitor C100, the amplitudes of currents I_E1 and I_E2 may become uneven when the voltages of the first secondary battery B1 and the second secondary battery B2 are different.

[0073] Figure 4 This diagram illustrates an example of the voltage and current changes generated in the AC generating circuit 10 due to the switching on / off of a sub-circuit in a comparative example of the first embodiment. The changes shown in this diagram are also the result of simulations performed by the inventors of this application. Figure 4 As shown, the amplitudes A1 and A2 of current I_E1 and I_E2 become non-uniform. As a result, the temperature rise of the first secondary battery B1 and the second secondary battery B2 deviates, and the AC generating device 1 sometimes fails to make the temperature rise of the first secondary battery B1 and the second secondary battery B2 uniform.

[0074] In contrast, according to the AC generating circuit 10 of the first embodiment, since a capacitor C100 is provided, the potential of the first intermediate connection point Q1 between the first sub-circuit and the second sub-circuit is adjusted, the amplitude of current I_E1 and the amplitude of current I_E2 become uniform, the AC generating device 1 can make the temperature of the first secondary battery B1 and the second secondary battery B2 rise uniformly, and reduce the loss caused by resistance.

[0075] <Second Implementation Method>

[0076] In the first embodiment, an example is shown where the secondary battery and the AC generation circuit each have two segments. Alternatively, the secondary battery and the AC generation circuit can each have three or more segments. In the second embodiment, the secondary battery and the AC generation circuit have three segments.

[0077] Figure 5 This diagram illustrates an example of the structure of the AC generating device 1A and the AC generating circuit 10A according to the second embodiment. In addition to the structure of the first embodiment, the second embodiment also includes a third sub-circuit 10-3.

[0078] The positive contact P11 of the third sub-circuit 10-3 is connected to the positive terminal of the third secondary battery B3 via fuse F. The negative contact P12 of the third sub-circuit 10-3 is connected to the first intermediate connection point Q1-2. Between contacts P11 and P12 are capacitors C7 and C8, and switches S7 to S9 for AC generation.

[0079] In the third sub-circuit 10-3, a first path connecting capacitor C7 and switch S7 in series, and a second path connecting switch S8 and capacitor C8 in series, exist in parallel between contacts P11 and P12. Contact P13, located between capacitor C7 and switch S7, and contact P14, located between switch S8 and capacitor C8, are connected via a third path. Switch S9 is provided in the third path. It should be noted that a second intermediate connection point Q2-2 is provided between the positive terminal of the second secondary battery B2 and the negative terminal of the third secondary battery B3.

[0080] A capacitor C200 is disposed between the first intermediate connection point Q1-2 and the second intermediate connection point Q2-2. The capacitor C200 selectively allows the AC component flowing between the first intermediate connection point Q1-2 and the second intermediate connection point Q2-2 to pass through, while suppressing the passage of the DC component. Other structures of the AC generation circuit 10A are the same as in the first embodiment, and therefore detailed descriptions are omitted.

[0081] Figure 6This diagram illustrates an example of the voltage and current changes generated in the AC generating circuit 10A due to the switching on / off of the sub-circuits in the second embodiment. In the first embodiment, the control unit 100 shifts the control phases of the switches of the first sub-circuit 10-1 and the second sub-circuit 10-2 by 180 degrees, causing the first sub-circuit 10-1 and the second sub-circuit 10-2 to generate AC currents of different phases. In contrast, in the second embodiment, the control unit 100 shifts the control phases of the switches of the first sub-circuit 10-1, the second sub-circuit 10-2, and the third sub-circuit 10-3 by 120 degrees, causing the first sub-circuit 10-1, the second sub-circuit 10-2, and the third sub-circuit 10-3 to generate AC currents of different phases. It should be noted that the principle of switching the connection relationship of the capacitors in each sub-circuit in the second embodiment to be connected in series / parallel relative to the corresponding secondary batteries is the same as in the first embodiment, therefore, detailed explanation is omitted.

[0082] In the second embodiment, capacitors C100 and C200 are provided, thus allowing a certain degree of AC component to pass through between the first intermediate connection point Q1-1 and the second intermediate connection point Q2-1, and between the first intermediate connection point Q1-2 and the second intermediate connection point Q2-2, while suppressing the rapid current flowing due to short circuits, etc. Therefore, even at the moment when the AC generating device 1A starts operating, the voltages of the first secondary battery B1, the second secondary battery B2, and the third secondary battery B3 are different, but AC is generated in a way that cancels out the differences in AC energy, and the amplitudes of the currents I_E1, I_E2, and I_E3 flowing through them become uniform. Furthermore, compared to the comparative example described later, no fuses are provided near the first intermediate connection point Q1-1 and the second intermediate connection point Q2-1, and near the first intermediate connection point Q1-2 and the second intermediate connection point Q2-2, thus reducing losses caused by resistance.

[0083] [Comparison with comparative examples]

[0084] (Comparative Example)

[0085] Here, a comparison with the comparative example of the second embodiment is explained. Figure 7 This is a diagram illustrating an example of the structure of the AC generation circuit in a comparative example of the second embodiment. Figure 7 In the accompanying drawings, parts having the same function as those in the second embodiment described above are labeled with the same reference numerals. The AC generation circuit of the comparative example is as follows: Figure 7 As shown, capacitors C100 and C200 are not installed. A fuse F1 is installed between contact P1 and the positive terminal of the first secondary battery B1, and a fuse F2 is installed between contact P6 and the positive terminal of the second secondary battery B2. In this case, the loss caused by the resistance of fuses F1 and F2 becomes greater. Figure 8 This diagram illustrates an example of the voltage and current variations generated in the AC generating circuit 10A due to the switching on / off of the sub-circuit in a comparative example of the second embodiment. In the comparative example, since capacitors C100 and C200 are absent, the amplitudes of currents I_E1, I_E2, and I_E3 sometimes become uneven when the voltages of the first secondary battery B1, the second secondary battery B2, and the third secondary battery B3 are different.

[0086] In contrast, in the AC generating circuit 10A of the second embodiment, since capacitors C100 and C200 are provided, capacitors C100 and C200 adjust the potentials of the first intermediate connection point Q1-1 and the second intermediate connection point Q1-2. As a result, the amplitudes of current I_E1, I_E2 and I_E3 become uniform, and the AC generating device 1A can make the temperatures of the first secondary battery B1, the second secondary battery B2 and the third secondary battery B3 rise uniformly, and reduce the losses caused by resistance.

[0087] <Third Implementation Method>

[0088] In the second embodiment, an example is illustrated where the secondary battery and AC generation circuit each have three segments, and a capacitor is provided between each of the two first intermediate connection points and the second intermediate connection point. Alternatively, when the secondary battery and AC generation circuit each have multiple segments, fuses may be provided at some or all of the locations where capacitors are not provided in the positions connecting the multiple first intermediate connection points and the multiple second intermediate connection points. In the third embodiment, a secondary battery and AC generation circuit with four segments are provided, and fuses are provided at the locations where capacitors are not provided in the positions connecting the multiple first intermediate connection points and the multiple second intermediate connection points.

[0089] Figure 9 This diagram illustrates an example of the structure of the AC generating device 1B and the AC generating circuit 10B according to the third embodiment. In addition to the structure of the second embodiment, the third embodiment also includes a fourth sub-circuit 10-4.

[0090] The positive contact P16 of the fourth sub-circuit 10-4 is connected to the positive terminal of the fourth secondary battery B4 via fuse F4. The negative contact P17 of the fourth sub-circuit 10-4 is connected to the first intermediate connection point Q1-3. Between contacts P16 and P17 are capacitors C10 and C11, and switches S10 to S12 for AC generation.

[0091] In the fourth sub-circuit 10-4, between contacts P16 and P17, there exists a first path connecting capacitor C10 and switch S10 in series, and a second path connecting switch S11 and capacitor C11 in series. Contact P18, located between capacitor C10 and switch S10, and contact P19, located between switch S11 and capacitor C11, are connected via a third path. Switch S12 is located in the third path. It should be noted that a second intermediate connection point Q2-3 is located between the positive terminal of the third secondary battery B3 and the negative terminal of the fourth secondary battery B4.

[0092] A capacitor C100 is provided between the first intermediate connection point Q1-1 and the second intermediate connection point Q2-1. A fuse F2 is provided between the first intermediate connection point Q1-2 and the second intermediate connection point Q2-2. A capacitor C300 is provided between the first intermediate connection point Q1-3 and the second intermediate connection point Q2-3. Capacitor C100 selectively allows the AC component flowing between the first intermediate connection point Q1-1 and the second intermediate connection point Q2-1 to pass through, while suppressing the DC component. Capacitor C300 selectively allows the AC component flowing between the first intermediate connection point Q1-3 and the second intermediate connection point Q2-3 to pass through, while suppressing the DC component. It should be noted that a fuse F1 can also be provided between contact P2 and contact P5. The functions of fuses F1 to F3 are the same; when the current flowing through them becomes greater than a certain current, they melt and cut off the current. Other structures of the AC generation circuit 10B are the same as in the second embodiment, so detailed descriptions are omitted.

[0093] In the third embodiment, since capacitors C100 and C300 are provided, a certain degree of alternating current can pass through between the first intermediate connection point Q1-1 and the second intermediate connection point Q2-1, and between the first intermediate connection point Q1-3 and the second intermediate connection point Q2-3, while suppressing the rapid current flowing due to short circuits, etc. Therefore, even at the moment when the AC generating device 1B starts operating, if the voltages of the first secondary battery B1 and the second secondary battery B2, or the third secondary battery B3 and the fourth secondary battery B4 are different, AC is generated in a way that cancels out the difference in AC energy, and the amplitudes of the currents I_E1 and I_E2, or the currents I_E3 and I_E4 flowing through them become uniform. In this way, compared to the case where fuses are installed between the first intermediate connection point Q1-1 and the second intermediate connection point Q2-1, between the first intermediate connection point Q1-2 and the second intermediate connection point Q2-2, and between the first intermediate connection point Q1-3 and the second intermediate connection point Q2-3, the absence of fuses near the first intermediate connection point Q1-1 and the second intermediate connection point Q2-1, and near the first intermediate connection point Q1-3 and the second intermediate connection point Q2-3, reduces losses caused by resistance. It should be noted that the structure can also be configured to omit fuse F2.

[0094] In the third embodiment, the control unit 100, for example, causes the control phases of the switches of the first sub-circuit 10-1, the second sub-circuit 10-2, the third sub-circuit 10-3, and the fourth sub-circuit 10-4 to be staggered by 90 degrees, so that the first sub-circuit 10-1, the second sub-circuit 10-2, the third sub-circuit 10-3, and the fourth sub-circuit 10-4 generate AC with different phases.

[0095] Therefore, in the AC generating circuit 10B of the third embodiment, since capacitors C100 and C300 are provided, capacitors C100 and C300 adjust the potentials of the first intermediate connection point Q1-1 and the third intermediate connection point Q1-3. As a result, the amplitudes of currents I_E1 and I_E2, and I_E3 and I_E4 become uniform. The AC generating device 1B can make the temperatures of the first secondary battery B1 and the second secondary battery B2, the third secondary battery B3 and the fourth secondary battery B4 rise uniformly, and can provide higher voltage, thereby reducing losses caused by resistance.

[0096] <Modification 1 of the Third Embodiment>

[0097] Hereinafter, a variation of the third embodiment 1 will be described. In variation 1 of the third embodiment, the structure is as follows: in at least one of the adjacent groups of the four secondary batteries and the AC generation circuit, there is no first intermediate connection point and no second intermediate connection point, and a fuse is provided on the side of any sub-circuit closer to the common intermediate connection point.

[0098] Figure 10 This diagram illustrates an example of the structure of the AC generating device 1C and AC generating circuit 10C in Modification 1 of the third embodiment. Compared to the third embodiment, in this modification, a capacitor C100 is provided between the first intermediate connection point Q1-1 and the second intermediate connection point Q2-1, and a fuse F2 is provided on the side of the second sub-circuit 10-2 near the common intermediate connection point QX between the second sub-circuit 10-2 and the third sub-circuit 10-3. A capacitor C300 is provided between the first intermediate connection point Q1-3 and the second intermediate connection point Q2-3, and a fuse F4 is provided between the first intermediate connection point Q1-4 and the second intermediate connection point Q2-4.

[0099] According to a variation of the third embodiment, the amplitudes of current I_E1 and I_E2, and the amplitudes of current I_E3 and I_E4 become uniform, and the AC generating device 1C can make the temperatures of the first secondary battery B1 and the second secondary battery B2, the third secondary battery B3 and the fourth secondary battery B4 rise uniformly, and reduce the loss caused by resistance.

[0100] <Modification 2 of the Third Embodiment>

[0101] Hereinafter, a variation 2 of the third embodiment will be described. In variation 1 of the third embodiment, the following structure was illustrated: in at least one group of adjacent groups of the four secondary batteries and the AC generating circuit, there is no first intermediate connection point and no second intermediate connection point; a fuse is provided on the side of any sub-circuit closer to the common intermediate connection point. In contrast, in variation 2 of the third embodiment, fuses are provided between the common intermediate connection point QX and the two sub-circuits connected to the common intermediate connection point QX.

[0102] Figure 11 This is a diagram illustrating an example of the structure of the AC generating device 1D and AC generating circuit 10D in Modification 2 of the third embodiment. In Modification 2 of the third embodiment, a fuse F2 is provided on the side of the second sub-circuit 10-2 at the common intermediate connection point QX between the second sub-circuit 10-2 and the third sub-circuit 10-3, and a fuse F3 is provided on the side of the third sub-circuit 10-3 at the common intermediate connection point QX.

[0103] According to a variation 2 of the third embodiment, the amplitudes of current I_E1 and I_E2, and the amplitudes of current I_E3 and I_E4 become uniform, and the AC generating device 1C can make the temperatures of the first secondary battery B1 and the second secondary battery B2, the third secondary battery B3 and the fourth secondary battery B4 rise uniformly, and improve the safety of the circuit by increasing the number of fuses.

[0104] <Regarding capacitor configuration>

[0105] Here, we will explain the configuration of a capacitor, such as capacitor C100, which is placed between the first intermediate connection point and the second intermediate connection point. Figure 12 This diagram illustrates an example of the configuration of a capacitor placed between the first intermediate connection point and the second intermediate connection point. The top diagram is a perspective view, and the bottom diagram is an exploded view viewed from the X direction shown in the diagram. It can also be configured as follows: Figure 12 As shown, the capacitor 240 (corresponding to capacitor C100, etc.) located between the first intermediate connection point and the second intermediate connection point is connected to the busbar 210, which connects multiple battery modules 200 as multiple secondary batteries, via the second connecting tab 220-2, and is connected to the branch busbar 230 via the first connecting tab 220-1. They can also be constructed with an insulating member, such as sealing the exposed busbar 210 and branch busbar 230 with a resin molding 250. The insulating member can be made of materials other than resin molding. When configured this way, the branch busbar 230 portion is insulated from the battery module 200 in the DC direction, and therefore will not become a live part. When assembling the battery package, it is not necessary to take measures to prevent short circuits on the exposed portion of the branch busbar 230.

[0106] The above description illustrates specific embodiments of the present invention, but the present invention is not limited to such embodiments in any way, and various modifications and substitutions can be made without departing from the spirit of the present invention.

Claims

1. An AC generating circuit, wherein, The AC generating circuit includes multiple sub-circuits connected to the positive and negative terminals of each of the multiple secondary batteries connected in series. In the plurality of sub-circuits, the negative terminal of one sub-circuit of two adjacent sub-circuits is connected to the positive terminal of the other sub-circuit through a first intermediate connection point. The first intermediate connection point is connected to the second intermediate connection point, which connects the negative terminal of one of two adjacent secondary batteries to the positive terminal of the other secondary battery. An intermediate capacitor is provided at least a portion of the locations between one or more first intermediate connection points and second intermediate connection points. The sub-circuit includes multiple switches and multiple sub-circuit capacitors, and AC is generated by switching the connection relationship of the sub-circuit capacitors to be connected in series / parallel relative to the corresponding secondary batteries.

2. The AC generating circuit according to claim 1, wherein, The intermediate capacitor is provided at each of the locations where the plurality of first intermediate connection points are connected to the plurality of second intermediate connection points.

3. The AC generating circuit according to claim 1, wherein, The intermediate capacitor is provided at a portion of the locations where multiple first intermediate connection points are connected to multiple second intermediate connection points. A current limiting element is provided in part or all of the locations where the intermediate capacitor is not provided in the positions connecting the plurality of first intermediate connection points and the plurality of second intermediate connection points.

4. The AC generating circuit according to claim 1, wherein, The intermediate capacitor, disposed between the first intermediate connection point and the second intermediate connection point, is connected via a first connecting piece to a branch busbar constituting the first intermediate connection point or connected to the first intermediate connection point, and via a second connecting piece to a busbar constituting the second intermediate connection point. The intermediate capacitor, the first connecting piece, and the second connecting piece are covered by an insulating member, and the branch busbar and at least a portion of the busbar are exposed outside the portion covered by the insulating member.

5. An AC generating device, wherein, The AC generating device includes: The AC generating circuit according to claim 1; and The control unit causes some or all of the plurality of sub-circuits to generate alternating current with different phases.

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