Alternating-current generation circuit and alternating-current generation device

Abstract

Provided are an alternating current generation circuit and an alternating current generation device, which can suppress the increase in size and price of a current limiting element and improve the protection performance of peripheral equipment by reducing the burden on the current limiting element and reducing the rated value of the current limiting element used. The alternating current generation circuit is installed in a secondary battery, and the alternating current generation circuit includes: a circuit that generates alternating current across the secondary battery; a current limiting element connected between the positive electrode side of the circuit and the positive electrode of the secondary battery and / or between the negative electrode side of the circuit and the negative electrode of the secondary battery; and a capacitor connected in parallel with the current limiting element.

Description

TECHNICAL FIELD

[0001] The present application relates to an alternating current generating circuit and an alternating current generating device. BACKGROUND

[0002] In order to reduce adverse effects on the global environment (for example, in order to reduce NOx, SOx, reduce CO2), electric vehicles that travel by power accumulated in a secondary battery are increasingly popular. It is known that when the temperature of a secondary battery falls below a moderate range, the charge-discharge characteristics of the secondary battery decrease. In relation to this, a temperature raising device for a secondary battery is disclosed, which, in the case where the temperature of the secondary battery is low, in order to raise the temperature thereof efficiently, is capable of efficiently raising the temperature of the secondary battery by causing the secondary battery to generate heat from the inside (for example, International Publication No. 2011 / 004464).

[0003] It is known that when the above-mentioned device that raises the temperature of a secondary battery is provided, in order to prevent a short-circuit current from being generated in a design circuit, a current limiting element is provided at a portion where an electricity storage body is connected to the circuit. In relation to this, a current suppression breaker unit is disclosed that is provided with a current limiting element in order to limit a short-circuit current (for example, Japanese Patent Application Laid-Open No. 11-25839). SUMMARY

[0004] The rated value of the current limiting element is set in cooperation with the size of the current that passes, so when the passing current of the alternating current generating circuit is large, a current limiting element with a large rated value needs to be used as the current limiting element. However, when the rated value of the current limiting element is large, the time required until the current limiting element starts to work is long, and it is possible that damage will be caused to the circuit or the like by the current during this period.

[0005] A scheme of the present application is completed in consideration of such things, and one of the objects thereof is to provide an alternating current generating circuit and an alternating current generating device that, by reducing the burden on a current limiting element, reduces the rated value of the current limiting element used, is able to suppress an increase in the size and price of the current limiting element, and improves the protection performance of peripheral equipment.

[0006] In order to solve the above-mentioned problem and achieve such an object, the present application adopts the following scheme.

[0007] (1) One scheme of the present application relates to an alternating current generating circuit that is installed in a secondary battery, in which the alternating current generating circuit is provided with: a circuit that generates an alternating current across the secondary battery; a current limiting element that is connected between the positive electrode side of the circuit and the positive electrode of the secondary battery, and / or between the negative electrode side of the circuit and the negative electrode of the secondary battery; and a capacitor that is connected in parallel with the current limiting element.

[0008] (2): In the aspect of (1) above, the circuit can generate the AC using the power stored in the secondary battery without relying on an external power source.

[0009] (3): In the aspect of (1) or (2) above, the circuit can include two or more in-circuit capacitors, and generate the AC by switching the connection relationship of the two or more in-circuit capacitors to be in series or parallel with respect to the secondary battery.

[0010] (4): One aspect of the present application relates to an AC generation device, wherein the AC generation device includes: the AC generation circuit according to any one of (1) to (3) above; and a control unit that causes the circuit to generate AC by controlling a switch included in the circuit.

[0011] According to the aspects of (1) to (4) above, by reducing the burden on the current limiting element and reducing the rated value of the current limiting element used, the size and price of the current limiting element can be suppressed, and the protection performance of the peripheral equipment can be improved.

[0012] According to the aspects of (2) or (3) above, the size and price of the current limiting element can be suppressed without the need for an external power source, the protection performance of the peripheral equipment can be ensured, and on this basis, the entire system can be made smaller and lighter, and energy efficiency can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a diagram showing one example of the structure of the AC generation device 1 and the AC generation circuit 10 of the first embodiment.

[0014] Figure 2 is a diagram showing one example of the change in current generated by the switching on / off of the switches of the circuit 10-A of the first embodiment.

[0015] Figure 3 is a diagram showing one example of the structure of the AC generation circuit 10# of the comparative example of the first embodiment.

[0016] Figure 4 is a diagram showing one example of the change in current generated by the switching on / off of the switches of the AC generation circuit 10# of the comparative example of the first embodiment.

[0017] Figure 5 is a diagram showing one example of the structure of the AC generation device 1X and the AC generation circuit 10X of the second embodiment. DETAILED DESCRIPTION

[0018] An embodiment of an alternating current generating circuit and an alternating current generating device according to the present application will be described below with reference to the accompanying drawings. The alternating current generating circuit and the alternating current generating device are installed in a secondary battery and warm the secondary battery when needed.

[0019] <First Embodiment>

[0020] Figure 1 is a diagram showing an example of the structure of the alternating current generating device 1 and the alternating current generating circuit 10 of the first embodiment. In the present embodiment, the alternating current generating device 1 includes the alternating current generating circuit 10 and a control section 100. The alternating current generating circuit 10 includes a circuit 10-A that generates alternating current, a capacitor C100, and a fuse F. The positive side of the circuit 10-A is connected to the positive electrode of a secondary battery B via the fuse F, and the negative side of the circuit 10-A is connected to the negative electrode of the secondary battery B. The capacitor C100 is connected in parallel with the fuse F.

[0021] In Figure 1 , the characteristics of the secondary battery B are assumed to be represented by an electric power storage section E, a resistor R S , and an inductor L S . The secondary battery B is, for example, a lithium ion battery or the like that can be repeatedly charged and discharged. The secondary battery B can be only one battery, or can include a plurality of battery modules that are electrically connected in series or in parallel with each other. The electric power supplied from the secondary battery B can also be supplied to a load via a DC-AC converter, a DC-DC converter, or the like, which are not shown.

[0022] A contact P1 on the positive side of the circuit 10-A is connected to a first end of the fuse F. A contact P2 on the negative side of the circuit 10-A is connected to a contact P5 that is the negative electrode of the secondary battery B. A capacitor C1 and a capacitor C2 for generating alternating current, and switches S1 to S3 are provided between the contact P1 and the contact P2. This structure corresponds to the circuit 10-A.

[0023] In the circuit 10-A, a first path in which the capacitor C1 and the switch S1 are connected in series, and a second path in which the switch S2 and the capacitor C2 are connected in series, are present in parallel between the contact P1 and the contact P2. A contact P3 between the capacitor C1 and the switch S1 and a contact P4 between the switch S2 and the capacitor C2 are connected by a third path. The switch S3 is provided in the third path.

[0024] A second end of the fuse F is connected to a contact P6. The fuse F is fused and cuts off the current when the current flowing therethrough is larger than a certain current. The fuse F is an example of a "current limiting element". Other current limiting elements such as a PTC (Positive Temperature Coefficient) thermistor or the like can also be used.

[0025] The capacitor C100 is provided in parallel with respect to the fuse F. That is, both ends of the capacitor C100 are connected to the contact P1 and the contact P6, respectively. The capacitor C100 selectively passes an alternating current component flowing between the contact P1 and the contact P6 and suppresses passage of a direct current component.

[0026] The control section 100 is realized by, for example, a CPU (Central Processing Unit), an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an IC (Integrated Circuit), or the like. The control section 100 causes the circuit 10-A to generate an alternating current by, for example, controlling the on / off of each of the switches S1 to S3 included in the circuit 10-A. In the present embodiment, the capacitor C1 and the capacitor C2 are examples of in-circuit capacitors, and their capacities are set to be the same. The capacity of the capacitor C100 can be the same as or different from the capacities of the in-circuit capacitors.

[0027] In the circuit 10-A, the control section 100 switches the capacitor C1 and the capacitor C2 to be connected in series / parallel with respect to the secondary battery B by, for example, controlling the switches S1, S2, S3. The control section 100 connects the capacitor C1 and the capacitor C2 in parallel with respect to the secondary battery B by turning on the switches S1 and S2 and turning off the switch S3, and connects the capacitor C1 and the capacitor C2 in series with respect to the secondary battery B by turning off the switches S1 and S2 and turning on the switch S3.

[0028] In a case where the capacitor C1 and the capacitor C2 are connected in parallel with respect to the secondary battery B, the voltage of each of the capacitor C1 and the capacitor C2 approaches the voltage of the secondary battery B (the capacitors are charged). On the other hand, in a case where the capacitor C1 and the capacitor C2 are connected in series with respect to the secondary battery B, the voltage of each of the capacitor C1 and the capacitor C2 approaches 1 / 2 of the voltage of the secondary battery B (the capacitors are discharged). An alternating current is generated between the circuit 10-A and the secondary battery B by repeating this case. The control section 100 controls the switches S1, S2, S3 as described above.

[0029] Figure 2is a graph showing an example of a change in current generated by the on / off of the switches of the circuit 10-A of the first embodiment. The change shown in this graph is a result obtained by simulation by the inventors of the present application. As shown in the graph, in the circuit 10-A, the capacitor Cl and the capacitor C2 are connected in series with respect to the secondary battery B at time tl. Before time tl, the sum of the voltages of the capacitor Cl and the capacitor C2 is larger than the voltage of the secondary battery B, and therefore, during a period from time tl to time t2, the capacitor Cl and the capacitor C2 are discharged, respectively, and charge the secondary battery B with the discharged electric power. At time t2, the capacitor Cl and the capacitor C2 are connected in parallel with respect to the secondary battery B. Before time t2, the voltages of the capacitor Cl and the capacitor C2 are smaller than the voltage of the secondary battery B, and therefore, during a period from time t2 to time t3, the capacitor Cl and the capacitor C2 are charged, respectively, and the secondary battery B is discharged. Due to the presence of the inductor Ls, the current I_El is maintained in a direction in which the capacitor Cl and the capacitor C2 flow to the secondary battery B, respectively, and therefore, the change in the waveform of the current I_El is slower than the change in the waveform of the voltage V1-V0 which is not shown, and the waveform of the current I_El is as shown in the graph.

[0030] Further, the capacitor C100 is provided in parallel with respect to the fuse F, and therefore, the alternating-current generation device 1 can reduce the alternating-current component passing through the fuse F side by passing most of the alternating-current component to the capacitor C100 side.

[0031] [Comparison between the first embodiment and the comparative example]

[0032] Here, a comparison between the first embodiment and the comparative example will be described. Figure 3 is a graph showing an example of the structure of the alternating-current generation circuit 10# of the comparative example of the first embodiment. In Figure 3 , the same reference numerals are attached to portions having the same functions as those of the above-described first embodiment. The alternating-current generation circuit 10# of the comparative example is not provided with the capacitor C100 as shown in Figure 3 , but only the fuse Fl is provided between the contact Pl and the contact P6.

[0033] Figure 4 is a graph showing an example of a change in current generated by the on / off of the switches of the alternating-current generation circuit 10# of the comparative example of the first embodiment. The change shown in this graph is also a result obtained by simulation by the inventors of the present application. As Figure 4As shown, in the comparative example, the current I_fuse flowing through the fuse F is the same as the current I_E1 flowing through the secondary battery B, but in the embodiment, it flows through the capacitor C100 exclusively, in contrast to the comparative example in which it flows through the fuse F. As a result, the current flowing through the fuse F when the AC generation circuit 10# is operating is larger in the comparative example than in the embodiment. Thus, a fuse F having a larger rated value than the embodiment needs to be used. When the rated value of the fuse F is large, the time required until the fuse F starts operating is long, and in the case where a large current flows during this period, there is a possibility that damage will be caused to the circuit or the like.

[0034] In contrast, according to the AC generation circuit 10 of the first embodiment, the capacitor C100 is provided, and thus when the secondary battery B is warmed up, the AC component passing through the fuse F side is reduced, whereby a fuse F having a small rated value can be used. When a fuse F having a small rated value is used, the time required until the fuse F starts operating is short, and the probability that a current will cause damage to the circuit or the like can be reduced. By reducing the rated value of the fuse F, the size and the price of the fuse F are suppressed from increasing. Also, because the capacitor C100 is provided, the protection performance of the peripheral equipment can also be ensured. According to the AC generation circuit 10 of the first embodiment, in addition to being able to achieve the effects described above, AC can be generated based on the charge accumulated in the secondary battery B, and thus an external power source is not required. Thus, the entire system can be made small and lightweight, and improvement in energy efficiency can be achieved.

[0035] According to the first embodiment described above, by reducing the rated value of the current limiting element (for example, a fuse) used by reducing the burden on the current limiting element, the size and the price of the current limiting element can be suppressed from increasing, and the protection performance of the peripheral equipment can be improved.

[0036] <Second Embodiment>

[0037] In the first embodiment, an example in which a combination of a fuse and a capacitor provided in parallel is provided between the positive electrode side of the circuit 10-A and the positive electrode of the secondary battery B (or between the negative electrode side of the circuit 10-A and the negative electrode of the secondary battery B) was illustrated. In the second embodiment, an example in which a combination of a fuse and a capacitor provided in parallel is provided between the positive electrode side of the circuit 10-A and the positive electrode of the secondary battery B, and between the negative electrode side of the circuit 10-A and the negative electrode of the secondary battery B will be described.

[0038] Figure 5 is a view showing an example of the structure of the AC generation device 1X and the AC generation circuit 10X of the second embodiment. In Figure 5 , the same reference numerals are affixed to portions having the same functions as those of the first embodiment. In the second embodiment, as Figure 5As shown, the positive side of the circuit 10X-A is connected to the positive electrode of the secondary battery B via the fuse Fl, and the negative side of the circuit 10X-A is connected to the negative electrode of the secondary battery B via the fuse F2. The capacitor C100 is connected in parallel with respect to the fuse Fl. The capacitor C110 is connected in parallel with respect to the fuse F2.

[0039] The contact Pl of the positive side of the circuit 10X-A is connected to the first end of the fuse Fl. The contact P2 of the negative side of the circuit 10X-A is connected to the first end of the fuse F2. The second end of the fuse Fl is connected to the contact P6, and the second end of the fuse F2 is connected to the contact P5.

[0040] The capacitor C100 is provided in parallel with respect to the fuse Fl. That is, both ends of the capacitor C100 are connected to the contact Pl and the contact P6, respectively. The capacitor C100 selectively passes an alternating current component flowing between the contact Pl and the contact P6, and suppresses passage of a direct current component. The capacitor C110 is provided in parallel with respect to the fuse F2. That is, both ends of the capacitor C110 are connected to the contact P2 and the contact P5, respectively. The capacitor C110 selectively passes an alternating current component flowing between the contact P2 and the contact P5, and suppresses passage of a direct current component. As for the other structures of the alternating current generation circuit 10X, the same as the first embodiment, detailed description is omitted.

[0041] In the second embodiment, the capacitor C100 is provided in parallel with respect to the fuse Fl, and the capacitor C110 is provided in parallel with respect to the fuse F2, and thus the alternating current generation device IX can reduce the alternating current component passing the fuse Fl and the fuse F2 side by passing most of the alternating current component on the capacitor C100 and the capacitor C110 side.

[0042] The alternating current generation circuit 10 according to the second embodiment is provided with the capacitor C100 and the capacitor C110, and thus can reduce the alternating current component passing the fuse Fl and the fuse F2 when warming up the secondary battery B, and thereby can use the fuse Fl and the fuse F2 having a small rated value. When using the fuse Fl and the fuse F2 having a small rated value, the time required until the fuse Fl and the fuse F2 start to work is short, and the probability of damage to the circuit or the like by the current can be reduced. Further, by reducing the rated value of the fuse Fl and the fuse F2, the increase in size and price of the fuse Fl and the fuse F2 can be suppressed. Further, since the capacitor C100 and the capacitor C110 are provided, the protection performance of the peripheral equipment can also be ensured. The alternating current can be generated based on the charge accumulated in the secondary battery B, and thus an external power source is not required either.

[0043] According to the AC generation circuit 10 of the second embodiment described above, in addition to being able to achieve the effects of the first embodiment, since the two fuses are respectively provided on the positive side and the negative side of the circuit 10X-A, it is also possible to improve the protection performance of the peripheral equipment.

[0044] The above describes the specific embodiments of the present application using the embodiments, but the present application is not at all limited by such embodiments, and various modifications and substitutions can be applied within the scope of the gist of the present application.

Claims

1. An alternating current generating circuit installed to a secondary battery, wherein the alternating current generating circuit comprises: a circuit that generates an alternating current across the secondary battery; a current limiting element connected between a positive electrode side of the circuit and a positive electrode of the secondary battery, and / or between a negative electrode side of the circuit and a negative electrode of the secondary battery; and a capacitor connected in parallel to the current limiting element, the circuit includes two or more intra-circuit capacitors, and generates the alternating current to warm up the secondary battery by switching a connection relationship of the two or more intra-circuit capacitors to be in series or parallel with respect to the secondary battery.

2. The alternating current generating circuit according to claim 1, wherein the circuit generates the alternating current using electric power accumulated by the secondary battery, without depending on an external power source.

3. An alternating current generating device, wherein the alternating current generating device comprises: the alternating current generating circuit according to claim 1 or 2; and a control section that causes the circuit to generate an alternating current by controlling a switch included in the circuit.

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