AC generating circuit and heating device

Abstract

To provide an AC generation circuit and a temperature-raising device, capable of more effectively raising the temperature of a secondary battery.SOLUTION: An AC generation circuit comprises: a first capacitor in which a first end side is connected to a positive electrode side of a power storage body including an inductance component; a second capacitor in which a second end side is connected to a negative electrode side of the power storage body; a parallel switch part that connects the first capacitor and the second capacitor to the power storage body; a DC switch part that serially connects the first capacitor and the second capacitor to the power storage body; a first inductor that is connected between the positive electrode side of the power storage body and a first end of the first capacitor; a second inductor that is connected between the second end of the second capacitor and the negative electrode side of the power storage body; a third capacitor that is connected between the second end of the first capacitor and the negative electrode side of the power storage body; and a fourth capacitor that is connected between the positive electrode side of the power storage body and the first end of the second capacitor.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an AC generating circuit and a temperature raising device. [Background technology]

[0002] Efforts to reduce adverse effects on the global environment (e.g., reduction of NOx, SOx, and CO2) are underway. Therefore, in recent years, from the perspective of improving the global environment and reducing CO2 emissions, there has been growing interest in electric vehicles, such as hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs), which are driven by at least an electric motor powered by a battery (secondary battery). The use of lithium-ion secondary batteries as in-vehicle batteries is being considered. In these electric vehicles, it is important to fully utilize the performance of secondary batteries. It is known that the charge / discharge performance of secondary batteries decreases when the temperature during use drops below a suitable range. The decrease in charge / discharge performance of secondary batteries can be suppressed by raising the temperature to a suitable level during use.

[0003] In this regard, for example, Patent Document 1 discloses a technology relating to a heating device for heating a secondary battery. The heating device disclosed in Patent Document 1 heats the secondary battery by actively generating in the secondary battery a ripple current of a predetermined frequency in a frequency range where the absolute value of the impedance is relatively low, based on the frequency characteristics of the impedance of the secondary battery. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5293820 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional technology, there are cases where the temperature of the secondary battery cannot be raised efficiently.

[0006] The present invention was made based on the recognition of the above-mentioned problems, and one of its objects is to provide an AC generating circuit and a heating device that can improve energy efficiency by more efficiently heating a secondary battery. [Means for solving the problem]

[0007] The AC generating circuit and the temperature raising device according to the present invention employ the following configuration. (1): An AC generating circuit according to one aspect of the present invention is an AC generating circuit that raises the temperature of a power storage device having an inductance component by generating an AC current based on power stored in the power storage device, the AC generating circuit including: a first capacitor having a first end connected to a positive electrode side of the power storage device; a second capacitor having a second end connected to a negative electrode side of the power storage device; a parallel switch unit that connects the second end of the first capacitor to the second end of the second capacitor and connects the first end of the first capacitor to the first end of the second capacitor, thereby connecting the first capacitor and the second capacitor in parallel to the power storage device; a series switch unit that connects the second end of the inductor to the first end of the second capacitor, thereby connecting the first capacitor and the second capacitor in series to the power storage unit; a first inductor connected between the positive electrode side of the power storage unit and the first end of the first capacitor; a second inductor connected between the second end of the second capacitor and the negative electrode side of the power storage unit; a third capacitor connected between the second end of the first capacitor and the negative electrode side of the power storage unit; and a fourth capacitor connected between the positive electrode side of the power storage unit and the first end of the second capacitor.

[0008] (2): In the above aspect (1), the inductance of the first inductor, the inductance of the second inductor, the capacitance of the first capacitor, the capacitance of the second capacitor, the capacitance of the third capacitor, and the capacitance of the fourth capacitor are adjusted based on a relational expression including the inductance components so that the current waveform of the AC current becomes close to a sine wave.

[0009] (3): In the above aspect (2), the relational expression adjusts the inductance of the first inductor, the inductance of the second inductor, the capacitance of the first capacitor, the capacitance of the second capacitor, the capacitance of the third capacitor, and the capacitance of the fourth capacitor so that the frequency of the AC current in a parallel state in which the first capacitor and the second capacitor are connected in parallel to the power storage unit matches the frequency of the AC current in a series state in which the first capacitor and the second capacitor are connected in series to the power storage unit.

[0010] (4) In the above aspect (3), the inductance of the first inductor and the inductance of the second inductor are equal to each other.

[0011] (5): In the above aspect (4), the capacitance of the first capacitor and the capacitance of the second capacitor are equal to each other.

[0012] (6): In the above aspect (5), the capacitance of the third capacitor and the capacitance of the fourth capacitor are equal to the second capacitance.

[0013] (7) In the above aspect (1), the inductance component includes an inductance component present in a wiring portion between the power storage unit and the AC generating circuit.

[0014] (8): In the above aspect (1), the parallel switch unit includes a first switch having a first terminal connected to the second end of the first capacitor and a second terminal connected to the second end of the second capacitor, and a second switch having a first terminal connected to the first end of the first capacitor and a second terminal connected to the first end of the second capacitor; the series switch unit includes a third switch having a first terminal connected to the first end of the second capacitor and a second terminal connected to the second end of the first capacitor; the first switch and the second switch are simultaneously controlled to a conductive state or a non-conductive state by a first control signal; the third switch is controlled to a conductive state or a non-conductive state by a second control signal; and a first state period during which the first control signal brings the first switch and the second switch into a conductive state and a second state period during which the second control signal brings the third switch into a conductive state do not overlap.

[0015] (9): In the above aspect (8), the power storage unit includes a first power storage unit and a second power storage unit connected in series to the first power storage unit, the AC generating circuit is connected to the first power storage unit, a second AC generating circuit having the same configuration as the AC generating circuit is connected to the second power storage unit, and the first control signal and the second control signal are input so as to give a predetermined phase difference between the AC current generated by the AC generating circuit and the second AC current which is the AC current generated by the second AC generating circuit.

[0016] (10): A temperature raising device according to one aspect of the present invention is a temperature raising device including the AC generating circuit of aspect (9) above, and a control unit that outputs the first control signal and the second control signal and alternately switches between a parallel state in which the first switch and the second switch are brought into a conductive state and the third switch is brought into a non-conductive state, thereby connecting the first capacitor and the second capacitor in parallel to the power storage unit, and a series state in which the first switch and the second switch are brought into a non-conductive state and the third switch is brought into a conductive state, thereby connecting the first capacitor and the second capacitor in series to the power storage unit, using the first control signal and the second control signal. [Effects of the Invention]

[0017] According to the above aspects (1) to (10), the temperature of the secondary battery can be raised more efficiently, thereby improving energy efficiency. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a diagram showing an example of the configuration of a vehicle in which a temperature raising device according to an embodiment is employed; [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of an AC generating circuit included in the temperature raising device according to the embodiment. [Figure 3] 1 is a diagram illustrating an example of an equivalent circuit of a series connection and a parallel connection in an AC generating circuit according to an embodiment. [Figure 4] FIG. 10 is a diagram illustrating an example of the configuration of an AC generating circuit of a comparative example. [Figure 5] 10 is an example of an equivalent circuit of an AC generating circuit of a comparative example. [Figure 6] 3 is an example of an equivalent circuit for explaining the resonance frequency of an AC current generated in the AC generating circuit of the embodiment. [Figure 7] FIG. 2 is a diagram illustrating an example of frequency characteristics of an AC current generated in the AC generating circuit according to the embodiment. [Figure 8] 10A and 10B are diagrams illustrating an example of the configuration and operating waveforms of a temperature raising device employing an AC generating circuit of a comparative example. [Figure 9] FIG. 10 is a diagram showing an example of another operating waveform of a temperature raising device employing an AC generating circuit of a comparative example. [Figure 10] 1 is a diagram showing an example of the configuration and operation waveforms of a temperature raising device employing an AC generating circuit according to an embodiment; [Figure 11] FIG. 10 is a diagram showing an example of another configuration of a temperature raising device employing an AC generating circuit according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an AC generating circuit and a temperature raising device according to the present invention will be described with reference to the drawings.

[0020] [Vehicle configuration] FIG. 1 is a diagram showing an example of the configuration of a vehicle employing a heating device according to an embodiment. The vehicle 1 is a hybrid electric vehicle (HEV) (hereinafter simply referred to as "vehicle") that runs by combining drive of an electric motor by power supplied from a battery (secondary battery) for driving, or drive of an internal combustion engine that uses fuel such as a diesel engine or a gasoline engine as an energy source. Vehicles to which the present invention is applicable include, for example, not only four-wheeled vehicles, but also saddle-ride type two-wheeled vehicles, three-wheeled vehicles (including vehicles with one front wheel and two rear wheels as well as vehicles with two front wheels and one rear wheel), and even assisted bicycles, and may be any vehicle that runs by an electric motor driven by power supplied from a battery for driving. The vehicle 1 may also be, for example, an electric vehicle (EV) that runs by drive of an electric motor only.

[0021] The vehicle 1 includes, for example, an engine 10, a motor 12, a reducer 14, drive wheels 16, a PDU (Power Drive Unit) 20, a battery 30, a battery sensor 32, a heating device 40, a driving operator 70, a vehicle sensor 80, and a control device 100.

[0022] The engine 10 is an internal combustion engine that outputs power by operating (rotating) through the combustion of fuel such as diesel or gasoline stored in a fuel tank (not shown) of the vehicle 1. The engine 10 is, for example, a reciprocating engine equipped with cylinders and pistons, intake valves, exhaust valves, a fuel injection device, spark plugs, connecting rods, a crankshaft, etc. The engine 10 may also be a rotary engine. The rotational power of the engine 10 is transmitted to a reduction gear 14.

[0023] The motor 12 is a rotating electric machine for propelling the vehicle 1. The motor 12 is, for example, a three-phase AC motor. A rotor of the motor 12 is connected to the reducer 14. The motor 12 is driven (rotated) by power supplied from the battery 30 via the PDU 20. The rotational power of the motor 12 is transmitted to the reducer 14. The motor 12 may generate power by operating as a regenerative brake using kinetic energy when the vehicle 1 decelerates. The motor 12 may include a power generating motor. The power generating motor generates power using the rotational power output by the engine 10, for example.

[0024] The reducer 14 is, for example, a differential gear. The reducer 14 transmits the driving force of the shaft to which the engine 10 or the motor 12 is connected, i.e., the rotational power of the engine 10 or the motor 12, to the axle to which the drive wheels 16 are connected. The reducer 14 may include, for example, a speed change mechanism, a so-called transmission mechanism, in which a plurality of gears and shafts are combined, and which changes the rotational speed of the engine 10 or the motor 12 according to a speed ratio (gear ratio) and transmits the rotational power to the axle. The reducer 14 may include, for example, a clutch mechanism that directly couples or separates the rotational power of the engine 10 or the motor 12 to the axle.

[0025] The PDU 20 is, for example, an inverter, a DC-DC converter, or an AC-DC converter. The PDU 20 converts DC power supplied from the battery 30 into three-phase AC power for driving the motor 12 and outputs the converted power to the motor 12. The PDU 20 may also include, for example, a VCU (Voltage Control Unit) that boosts the DC power supplied from the battery 30. The PDU 20 converts three-phase AC power generated by the motor 12 operating as a regenerative brake into DC power and outputs the DC power to the battery 30. The PDU 20 may boost or lower the voltage of the power before outputting it according to its output destination. While FIG. 1 shows the components of the PDU 20 as a single unit, this is merely an example, and the components of the PDU 20 may be distributed throughout the vehicle 1.

[0026] The battery 30 is a battery for propelling the vehicle 1. The battery 30 includes a secondary battery, such as a lithium-ion battery, that can be repeatedly charged and discharged, as a power storage unit. The battery 30 may be configured to be easily detachable from the vehicle 1, such as a cassette-type battery pack, or may be a fixed type that is not easily detachable from the vehicle 1. The secondary battery included in the battery 30 is, for example, a lithium-ion battery. The secondary battery may be, for example, a lead-acid battery, a nickel-metal hydride battery, a sodium-ion battery, a capacitor such as an electric double layer capacitor, or a combination battery that combines a secondary battery and a capacitor. However, the secondary battery may have any configuration. The battery 30 stores (charges) power supplied from a charger (not shown) external to the vehicle 1 and discharges the stored power to propel the vehicle 1. The battery 30 stores (charges) the electric power supplied via the PDU 20 and generated by the motor 12 operating as a regenerative brake, and discharges the stored electric power for running (for example, accelerating) the vehicle 1. The battery 30 has at least an inductance component.

[0027] The battery 30 is an example of an “electricity storage unit.” The inductance component of the battery 30 (the inductance component connected to the electricity storage unit of the battery 30) is an example of an “inductance component.”

[0028] A battery sensor 32 is connected to the battery 30. The battery sensor 32 detects physical quantities such as the voltage, current, and temperature of the battery 30. The battery sensor 32 includes, for example, a voltage sensor, a current sensor, and a temperature sensor. The battery sensor 32 detects the voltage of the battery 30 using a voltage sensor, detects the current of the battery 30 using a current sensor, and detects the temperature of the battery 30 using a temperature sensor. The battery sensor 32 outputs information such as the detected voltage value, current value, and temperature of the battery 30 (hereinafter referred to as "battery information") to the control device 100.

[0029] The temperature raising device 40 raises the temperature of the battery 30 in accordance with control from the control device 100. The temperature raising device 40 includes an AC generating circuit 42 and a control unit 44, for example.

[0030] The AC generating circuit 42 includes, for example, a capacitor connected to the positive electrode side of the battery 30, a capacitor connected to the negative electrode side of the battery 30, a series switch unit connecting the respective capacitors in series to the battery 30, and a parallel switch unit connecting the respective capacitors in parallel to the battery 30. The AC generating circuit 42 generates an AC current (ripple current) through resonance between an inductance component of the battery 30 and at least the capacitor connected to the positive electrode side. More specifically, the AC generating circuit 42 generates an AC current based on the power stored in the battery 30 through resonance that alternates between magnetic energy stored in the inductance component of the battery 30 and electrostatic energy stored in at least the capacitor connected to the positive electrode side. The AC generating circuit 42 applies (passes) the generated AC current to the battery 30, thereby raising the temperature of the battery 30.

[0031] The control unit 44 switches the connection of each capacitor to the battery 30 between a series connection and a parallel connection by turning on or off the series switch unit and the parallel switch unit included in the AC generating circuit 42. More specifically, the control unit 44 alternately switches between a state in which each capacitor is connected in series to the battery 30 by turning on the series switch unit and the parallel switch unit and turning off the parallel switch unit, and a state in which each capacitor is connected in parallel to the battery 30 by turning on the series switch unit and the parallel switch unit and turning on the parallel switch unit. At this time, the control unit 44 may switch the connection of each capacitor to the battery 30 from a series connection to a parallel connection, or vice versa, by preventing overlapping of periods in which both the series switch unit and the parallel switch unit are turned on. In other words, the control unit 44 may switch the connection of each capacitor to the battery 30 from a series connection to a parallel connection, or vice versa, by providing a period in which both the series switch unit and the parallel switch unit are turned off, i.e., a dead time.

[0032] The state in which each capacitor is connected in series to the battery 30 is an example of a "series state," and the state in which each capacitor is connected in parallel to the battery 30 is an example of a "parallel state." Details of the temperature raising device 40 and the components included in the temperature raising device 40 will be described later.

[0033] The driving operators 70 include, for example, an accelerator pedal, a brake pedal, a shift lever, a steering wheel, an irregular steering wheel, a joystick, and other operators. The driving operators 70 are equipped with sensors that detect whether or not each operator is operated by the user (driver) of the vehicle 1, or the amount of operation. The driving operators 70 output the detection results of the sensors to the control device 100.

[0034] The vehicle sensor 80 detects the traveling state of the vehicle 1. The vehicle sensor 80 includes, for example, a vehicle speed sensor that detects the speed of the vehicle 1 and an acceleration sensor that detects the acceleration of the vehicle 1. The vehicle sensor 80 outputs the detection results detected by each sensor to the control device 100.

[0035] The control device 100 controls the operation and behavior of the engine 10 and the motor 12 in accordance with the detection results output by the sensors provided in the driving operators 70, i.e., the operation of the operators by the user (driver) of the vehicle 1. In other words, the control device 100 controls the driving force of the motor 12. The control device 100 may be configured with separate control devices, such as an engine control unit, a motor control unit, a battery control unit, a PDU control unit, and a VCU control unit. The control device 100 may be replaced with a control device such as an engine ECU (Electronic Control Unit), a motor ECU, a battery ECU, a PDU-ECU, or a VCU-ECU.

[0036] When the vehicle 1 is traveling, the control device 100 controls the amount of AC power supplied from the battery 30 to the motor 12 and the frequency (i.e., voltage waveform) of the supplied AC power. At this time, the control device 100 controls the activation of the temperature raising device 40 based on information about the temperature of the battery 30 included in the battery information output by the battery sensor 32. That is, the control device 100 controls the activation or stopping of the temperature raising device 40 so as to raise (heat up) the temperature of the battery 30 to a temperature suitable for use, in order to suppress a deterioration in the charge / discharge performance of the battery 30.

[0037] The control device 100 operates by, for example, a hardware processor such as a CPU (Central Processing Unit) executing a program (software). The control device 100 may be realized by hardware (including circuitry) such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit), or may be realized by a combination of software and hardware. The control device 100 may be realized by a dedicated LSI. The program may be stored in advance in a storage device (storage device having a non-transitory storage medium) such as an HDD (Hard Disk Drive) or flash memory provided in the vehicle 1, or may be stored in a removable storage medium (non-transitory storage medium) such as a DVD or CD-ROM, and installed in the HDD or flash memory provided in the vehicle 1 by inserting the storage medium into a drive device provided in the vehicle 1.

[0038] [Configuration of AC generating circuit equipped in heating device] Fig. 2 is a diagram showing an example of the configuration of an AC generating circuit 42 included in the temperature raising device 40 according to the embodiment. Fig. 2 also shows a battery 30 associated with the AC generating circuit 42. In the battery 30, for example, a resistance Ra and an inductance La are connected in series to the positive electrode side of a power storage unit Ba. The inductance La connected to the power storage unit Ba included in the battery 30 is an example of an "inductance component."

[0039] The AC generating circuit 42 includes, for example, a capacitor C10, a capacitor C11, a capacitor C20, a capacitor C21, a switch S11, a switch S12, a switch S13, an inductor L10, and an inductor L20.

[0040] A first terminal of the capacitor C10 is connected to the positive terminal of the battery 30 via the inductor L10. More specifically, a first terminal of the capacitor C10 is connected to the second terminal of the inductor L10, and a first terminal of the inductor L10 is connected to the positive terminal of the battery 30. Furthermore, a first terminal of the capacitor C10 is connected to a first terminal of the switch S12. A second terminal of the capacitor C10 is connected to a first terminal of the capacitor C11. Furthermore, a second terminal of the capacitor C10 is connected to a first terminal of the switch S11 and a second terminal of the switch S13. A second terminal of the capacitor C11 is connected to the negative terminal of the battery 30. A second terminal of the capacitor C20 is connected to the negative terminal of the battery 30 via the inductor L20. More specifically, a second terminal of the capacitor C20 is connected to the first terminal of the inductor L20, and a second terminal of the inductor L20 is connected to the negative terminal of the battery 30. That is, the negative electrode side of the battery 30 is connected to the second terminal of the capacitor C11 and the second terminal of the inductor L20. Furthermore, the second terminal of the capacitor C20 is connected to the second terminal of the switch S11. The first terminal of the capacitor C20 is connected to the second terminal of the capacitor C21. Furthermore, the first terminal of the capacitor C20 is connected to the second terminal of the switch S12 and the first terminal of the switch S13. The first terminal of the capacitor C21 is connected to the positive electrode side of the battery 30. That is, the positive electrode side of the battery 30 is connected to the first terminal of the inductor L10 and the first terminal of the capacitor C21.

[0041] Each of the capacitors C10 and C20 is a capacitor that can be switched between a state in which it is connected in series to the battery 30 (series state) and a state in which it is connected in parallel to the battery 30 (parallel state). Each of the capacitors C10 and C20 is switched between a state in which it is connected in series to the battery 30 and a state in which it is connected in parallel to the battery 30, thereby generating an AC current (ripple current) through resonance with the inductance component of the battery 30. Each of the capacitors C10 and C20 has the same electrostatic capacitance. Each of the capacitors C11, C21, inductor L10, and inductor L20 is a component that adjusts the overall impedance of the AC generating circuit 42 so that it is similar when the capacitors C10 and C20 are connected in series to the battery 30 and when they are connected in parallel. Each of the capacitors C11 and C21 has the same capacitance. The inductor L10 and the inductor L20 have the same inductance.

[0042] Each of the switches S11, S12, and S13 is controlled to a conductive state in which both terminals are connected (closed state) or a non-conductive state in which both terminals are not connected (open state) in response to a control signal output by the control unit 44. The switches S11 and S12 are controlled by the control unit 44 as a parallel switch unit that connects the capacitors C10 and C20 in parallel to the battery 30. The switch S13 is controlled by the control unit 44 as a series switch unit that connects the capacitors C10 and C20 in series to the battery 30.

[0043] Each of the switches S11, S12, and S13 may be a semiconductor switching element that is controlled to either an on or off state, such as an N-channel metal oxide semiconductor field effect transistor (MOSFET). In this case, for example, a diode that functions as a reflux rectifier may be further connected in parallel. When the switches S11, S12, and S13 are each configured as a semiconductor switching element, the control unit 44 outputs a gate signal that turns the semiconductor switching element on or off as a control signal that controls each of the switches S11, S12, and S13 to a conductive state or a non-conductive state.

[0044] In the following description, the control signal output by the control unit 44 for controlling the switch S11 to a conductive state or a non-conductive state will be referred to as the "control signal CS11," the control signal for controlling the switch S12 to a conductive state or a non-conductive state will be referred to as the "control signal CS12," and the control signal for controlling the switch S13 to a conductive state or a non-conductive state will be referred to as the "control signal CS13." When the switches S11 and S12 are controlled simultaneously as a parallel switch unit, the control unit 44 may output the control signal CS11 and the control signal CS12 as the same control signal CS.

[0045] With this configuration, in the AC generating circuit 42, capacitors C10 and C20 are connected in series or in parallel between the positive and negative terminals of battery 30 in accordance with control from the control unit 44. More specifically, the control unit 44 outputs a control signal CS11 to switch S11 to place it in a non-conductive state, a control signal CS12 to switch S12 to place it in a non-conductive state, and a control signal CS13 to switch S13 to place it in a conductive state, thereby connecting capacitors C10 and C20 in series between the positive and negative terminals of battery 30. Meanwhile, the control unit 44 outputs a control signal CS11 to switch S11 to place it in a conductive state, a control signal CS12 to switch S12 to place it in a conductive state, and a control signal CS13 to switch S13 to place it in a non-conductive state, thereby connecting capacitors C10 and C20 in parallel between the positive and negative terminals of battery 30.

[0046] In the AC generating circuit 42, the capacitor C10 is an example of a "first capacitor," the capacitor C20 is an example of a "second capacitor," the capacitor C11 is an example of a "third capacitor," and the capacitor C21 is an example of a "fourth capacitor." In the AC generating circuit 42, the switch S11 is an example of a "first switch," the switch S12 is an example of a "second switch," and the switch S13 is an example of a "third switch." In the AC generating circuit 42, the inductor L10 is an example of a "first inductor," and the inductor L20 is an example of a "second inductor." The control signal CS11 that the control unit 44 outputs to the switch S11 and the control signal CS12 that the control unit 44 outputs to the switch S12 are examples of a "first control signal," and the control signal CS13 that the control unit 44 outputs to the switch S13 is an example of a "second control signal." The state in which the control unit 44 turns on both the switches S11 and S12 using the control signals CS11 and CS12 is an example of a "first state." The state in which the control unit 44 turns on the switch S13 using the control signal CS13 is an example of a "second state." The state in which the control unit 44 turns on both the switches S11 and S12 using the control signals CS11 and CS12 and turns on the switch S13 using the control signal CS13 is an example of a "series state." The state in which the control unit 44 turns on both the switches S11 and S12 using the control signals CS11 and CS12 and turns on the switch S13 using the control signal CS13 is an example of a "parallel state."

[0047] [Operation of AC generating circuit] Here, let us consider the frequency of the AC current generated by the AC generating circuit 42. In order to efficiently raise the temperature of the battery 30 by the temperature raising device 40, it is preferable that the AC current generated by the AC generating circuit 42 has a sine wave waveform.

[0048] As described above, in the AC generating circuit 42, the capacitors C10 and C20 have the same capacitance. Therefore, when the capacitors C10 and C20 are connected in series to the battery 30, the overall capacitance of the capacitors C10 and C20, when considered as a single capacitor, differs between the cases where the capacitors C10 and C20 are connected in parallel to the battery 30. More specifically, when the capacitors C10 and C20 are connected in series, the overall capacitance of the AC generating circuit 42 is the sum of the reciprocals of the capacitances of the individual capacitors, i.e., half the capacitance. On the other hand, when the capacitors C10 and C20 are connected in parallel, the overall capacitance of the AC generating circuit 42 is the sum of the capacitances of the individual capacitors, i.e., double the capacitance. In other words, when the capacitors C10 and C20 are connected in series to the battery 30, the overall capacitance of the AC generating circuit 42 differs by four times between the cases where the capacitors C10 and C20 are connected in parallel to the battery 30. Therefore, in the AC generating circuit 42, the frequency of the AC current generated when the capacitors C10 and C20 are connected in series to the battery 30 differs by two times from that when they are connected in parallel.

[0049] Here, the difference between connecting capacitors C10 and C20 in series and in parallel to the battery 30 in the AC generating circuit 42 will be described. FIG. 3 shows an example of an equivalent circuit for a series connection and a parallel connection in the AC generating circuit 42 of this embodiment. FIG. 3(a) shows an equivalent circuit for connecting capacitors C10 and C20 in series to the battery 30, and FIG. 3(b) shows an equivalent circuit for connecting capacitors C10 and C20 in parallel to the battery 30. FIGS. 3(a) and 3(b) show equivalent circuits for the AC generating circuit 42 shown in FIG. 2, in which switches S11, S12, and S13 are simply set to a conductive state or a non-conductive state. In FIGS. 3(a) and 3(b), the inductance component of inductance La of the battery 30 is designated "Ls," and the resistance component of resistance Ra is designated "Rs." In Figures 3(a) and 3(b), the capacitance of capacitors C10 and C20 is "Cx," the capacitance of capacitors C11 and C21 is "Cy," and the inductance of inductors L10 and L20 is "Lx."

[0050] The capacitance Cx of the capacitors C10 and C20 is an example of a "first capacitance," and the capacitance Cy of the capacitors C11 and C21 is an example of a "second capacitance."

[0051] 3(a), when the capacitors C10 and C20 are connected in series to the battery 30 in the AC generating circuit 42, an inductor L10 is inserted in series between the capacitor C10 and the positive electrode of the battery 30, a capacitor C11 is inserted in series between the capacitor C10 and the negative electrode of the battery 30, an inductor L20 is inserted in series between the capacitor C20 and the negative electrode of the battery 30, and a capacitor C21 is inserted in series between the capacitor C20 and the positive electrode of the battery 30. In contrast, when the capacitors C10 and C20 are connected in parallel to the battery 30 in the AC generating circuit 42, as shown in FIG. 3(b), a parallel circuit of the capacitor C21 and inductor L10 is inserted in series between the capacitors C10 and C20 and the positive electrode of the battery 30, and a parallel circuit of the capacitor C11 and inductor L20 is inserted in series between the capacitors C10 and C20 and the negative electrode of the battery 30. In this way, in the AC generating circuit 42, the frequency of the AC current generated when the capacitors C10 and C20 are connected in series and in parallel can be made the same by changing the connection of the capacitors C11, C21, inductor L10, and inductor L20 between when the capacitors C10 and C20 are connected in series and when they are connected in parallel. Furthermore, in the AC generating circuit 42, the current waveform of the AC current generated when the capacitors C10 and C20 are connected in series and in parallel can be made closer to a sine wave.

[0052] <Comparative Example> [Configuration of AC generating circuit of comparative example] Here, to explain the effects of the configuration of the AC generating circuit 42, first, an AC generating circuit of a comparative example (hereinafter referred to as "AC generating circuit 42C") that does not include capacitor C11, capacitor C21, inductor L10, and inductor L20 will be explained. Fig. 4 is a diagram showing an example of the configuration of the AC generating circuit 42C of the comparative example.

[0053] The AC generating circuit 42C includes, for example, a capacitor C1, a capacitor C2, a switch S1, a switch S2, and a switch S3. Capacitor C1 and capacitor C2 have the same capacitance. Each of switches S1, S2, and S3 is controlled to place both terminals in a conductive or non-conductive state in response to, for example, a control signal CS output by the control unit 44. In the following description, the control signal output by the control unit 44 for controlling switch S1 to be in a conductive or non-conductive state is referred to as a "control signal CS1," the control signal for controlling switch S2 to be in a conductive or non-conductive state is referred to as a "control signal CS2," and the control signal for controlling switch S3 to be in a conductive or non-conductive state is referred to as a "control signal CS3."

[0054] A first terminal of the capacitor C1 is connected to the positive terminal of the battery 30. Furthermore, the first terminal of the capacitor C1 is connected to a first terminal of the switch S2. A second terminal of the capacitor C1 is connected to a first terminal of the switch S1 and a second terminal of the switch S3. A second terminal of the capacitor C2 is connected to the negative terminal of the battery 30. Furthermore, the second terminal of the capacitor C2 is connected to the second terminal of the switch S1. The first terminal of the capacitor C2 is connected to the second terminal of the switch S2 and a first terminal of the switch S3.

[0055] In the AC generating circuit 42C, the capacitor C1 corresponds to the capacitor C10 included in the AC generating circuit 42, and the capacitor C2 corresponds to the capacitor C20 included in the AC generating circuit 42. In the AC generating circuit 42C, the switch S1 corresponds to the switch S11 included in the AC generating circuit 42, and the switch S2 corresponds to the switch S12 included in the AC generating circuit 42. In the AC generating circuit 42C, the switch S3 corresponds to the switch S13 included in the AC generating circuit 42. Therefore, the AC generating circuit 42C has a configuration in which the capacitors C11, C21, inductor L10, and inductor L20 are omitted from the AC generating circuit 42.

[0056] Fig. 5 is an example of an equivalent circuit of an AC generating circuit 42C of a comparative example. Fig. 5(a) shows an equivalent circuit in which capacitors C1 and C2 in the AC generating circuit 42C are connected in series to the battery 30, and Fig. 5(b) shows an equivalent circuit in which capacitors C1 and C2 in the AC generating circuit 42C are connected in parallel to the battery 30. In Fig. 5, as with the equivalent circuits of the AC generating circuit 42 shown in Figs. 3(a) and 3(b), the inductance component of the inductance La of the battery 30 is designated "Ls," and the resistance component of the resistance Ra is designated "Rs." The capacitance of capacitors C1 and C2 is designated "Cx."

[0057] Here, the frequency of the AC current generated by the AC generating circuit 42C will be described with reference to Fig. 5. In the AC generating circuit 42C, when the capacitors C1 and C2 are connected in series as shown in Fig. 5(a), the impedance Z can be calculated by the following equation (1).

[0058]

number

[0059] The resonant frequency ωs, which is the angular frequency when the capacitors C1 and C2 are connected in series in the AC generating circuit 42C, can be calculated by the following equation (2).

[0060]

number

[0061] On the other hand, in the AC generating circuit 42C, when the capacitors C1 and C2 are connected in parallel as shown in FIG. 5(b), the impedance Z can be calculated by the following equation (3).

[0062]

number

[0063] The resonant frequency ωp, which is the angular frequency when the capacitors C1 and C2 are connected in parallel in the AC generating circuit 42C, can be calculated by the following equation (4).

[0064]

number

[0065] In the AC generating circuit 42C, the resonant frequency ωs when the capacitors C1 and C2 are connected in series is compared with the resonant frequency ωp when the capacitors C1 and C2 are connected in parallel, resulting in a ratio expressed by the following equation (5).

[0066]

number

[0067] That is, in the AC generating circuit 42C, the resonant frequency ω differs depending on the difference in overall capacitance between when the capacitors C1 and C2 are connected in series and when they are connected in parallel. More specifically, the resonant frequency ωs when the capacitors C1 and C2 are connected in series is twice the resonant frequency ωp when the capacitors C1 and C2 are connected in parallel. Therefore, the AC generating circuit 42C generates an AC current that is not sinusoidal, but rather has an asymmetric current waveform when the AC current has a positive current value and a negative current value. Therefore, the AC generating circuit 42C generates an AC current that contains many harmonic components, which results in the emission of a large amount of noise when the battery 30 is heated.

[0068] For this reason, for example, when the battery 30 mounted on the vehicle 1 is configured as a combination of multiple batteries 30, the efficiency of the AC generating circuit 42C in raising the temperature of the battery 30 decreases. For example, when the battery 30 is configured as a combination of two batteries 30, it is conceivable to connect the AC generating circuit 42C to each battery 30 and provide a predetermined phase difference between the waveforms of the AC currents generated by the respective AC generating circuits 42C to reduce the overall voltage fluctuation (so-called voltage waveform ripple) when raising the temperature of the battery 30. In other words, it is conceivable to reduce the overall voltage fluctuation when raising the temperature of the battery 30 by shifting the phases of the current waveforms of the AC currents generated by the respective AC generating circuits 42C by a predetermined phase. However, the AC generating circuit 42C cannot sufficiently reduce the overall voltage fluctuation because the current waveforms of the AC currents are asymmetric between positive and negative. Therefore, a temperature raising device that employs the AC generating circuit 42C (hereinafter referred to as "temperature raising device 40C") cannot raise the temperature of the battery 30 efficiently.

[0069] Returning to Fig. 3, we will explain the frequency of the AC current generated by the AC generating circuit 42. First, consider the resonant frequency ωs, which is the angular frequency when the capacitors C10 and C20 are connected in series, as shown in Fig. 3(a).

[0070] The impedance Zs when the capacitors C10 and C20 are connected in series in the AC generating circuit 42 can be calculated from the equivalent circuit shown in FIG. 3(a) using the following equation (6).

[0071]

number

[0072] Based on the above equation (6), the impedance Zs when the capacitors C10 and C20 are connected in series in the AC generating circuit 42 can be expressed as in the following equation (7).

[0073]

number

[0074] That is, the impedance Zs can be calculated as in the following equation (8).

[0075]

number

[0076] For this reason, the resonance point of the AC current generated when the capacitors C10 and C20 are connected in series in the AC generating circuit 42 is a point that satisfies the condition that the first term on the right-hand side of the above equation (8) becomes zero. In other words, the point where the impedance Zs and the resistance component Rs of the resistance Ra of the battery 30 become equal (the following equation (9) is satisfied) is the resonance point of the AC current generated when the capacitors C10 and C20 are connected in series in the AC generating circuit 42.

[0077]

number

[0078] Therefore, in order to satisfy the above equation (9), the numerator of the first term on the right side of the above equation (8) must be zero, as expressed in the following equation (10), provided that the denominator of the first term on the right side of the above equation (8) is not zero.

[0079]

number

[0080] Therefore, when the capacitors C10 and C20 are connected in series in the AC generating circuit 42, the resonant frequency ωs that satisfies the above equation (9) can be expressed by the following equation (11).

[0081]

number

[0082] Here, the inductance Lx of inductors L10 and L20 included in the above equation (11) is replaced by the ratio to the inductance component Ls of the inductance La of battery 30, and the capacitance Cx of capacitors C10 and C20 is replaced by the ratio to the capacitance Cy of capacitors C11 and C21. That is, as in the following equation (12), the inductance Lx is replaced by the inductance component Ls multiplied by a coefficient a, and the capacitance Cx is replaced by the capacitance Cy multiplied by a coefficient b. As a result, the above equation (11) is expressed as the following equation (13).

[0083]

number

[0084]

number

[0085] The solution of the quadratic equation expressed by the above equation (13) is the resonant frequency ωs when the capacitors C10 and C20 are connected in series in the AC generating circuit .

[0086] Next, consider the resonant frequency ωp, which is the angular frequency when the capacitors C10 and C20 are connected in parallel as shown in FIG. 3(b).

[0087] The impedance Zp when the capacitors C10 and C20 are connected in parallel in the AC generating circuit 42 can be calculated from the equivalent circuit shown in FIG. 3(b) by the following equation (14).

[0088]

number

[0089] Based on the above equation (14), the impedance Zp when the capacitors C10 and C20 are connected in parallel in the AC generating circuit 42 can be expressed as in the following equation (15).

[0090]

number

[0091] That is, the impedance Zp can be calculated as in the following equation (16).

[0092]

number

[0093] Therefore, in the same way as when the capacitors C10 and C20 are connected in series, the resonance point of the AC current generated when the capacitors C10 and C20 are connected in parallel in the AC generating circuit 42 is a point that satisfies the condition that the first term on the right-hand side of the above equation (16) becomes zero. In other words, the point where the impedance Zp and the resistance component Rs of the resistance Ra of the battery 30 become equal (the following equation (17) is satisfied) is the resonance point of the AC current generated when the capacitors C10 and C20 are connected in parallel in the AC generating circuit 42.

[0094]

number

[0095] Therefore, in order to satisfy the above equation (17), the numerator of the first term on the right side of the above equation (16) must be zero, as expressed in the following equation (18), provided that the denominator of the first term on the right side of the above equation (16) is not zero.

[0096]

number

[0097] Therefore, when the capacitors C10 and C20 are connected in parallel in the AC generating circuit 42, the resonant frequency ωp that satisfies the above equation (17) can be expressed by the following equation (19).

[0098]

number

[0099] Here, as in the case where capacitors C10 and C20 are connected in series, if the inductance Lx and capacitance Cx included in the above equation (19) are replaced with those in the above equation (12), then the above equation (19) can be expressed as the following equation (20).

[0100]

number

[0101] The solution of the quadratic equation expressed by the above equation (20) is the resonant frequency ωp when the capacitors C10 and C20 are connected in parallel in the AC generating circuit .

[0102] Therefore, in order to make the resonant frequency ωs when the capacitors C10 and C20 are connected in series and the resonant frequency ωp when the capacitors C10 and C20 are connected in parallel in the AC generating circuit 42 equal (to the following equation (21)), it is sufficient to make the following equation (22) hold based on the above equations (13) and (20).

[0103]

number

[0104]

number

[0105] Here, when the above equation (22) is calculated, the following equation (23) is obtained, and when further calculated, the following equation (24) is obtained.

[0106]

number

[0107]

number

[0108] Then, from the above equation (24), the following relational equation (25) can be obtained.

[0109]

number

[0110] If the above equation (25) is established, then the above equation (21) is established in the AC generating circuit 42, that is, the resonant frequency ωs when the capacitors C10 and C20 are connected in series and the resonant frequency ωp when the capacitors C10 and C20 are connected in parallel are equal (match).

[0111] Here, when the above equation (25) is further expanded, the square of the left side of the above equation (25) becomes the below equation (26), and the square of the right side of the above equation (25) becomes the below equation (27).

[0112]

number

[0113]

number

[0114] Then, if the relationship between coefficient a and coefficient b when the squares of both sides of equation (25) above (equations (26) and (27)) are equal is found as in equation (28) below, we can obtain the relational expression shown in equation (29) below.

[0115]

number

[0116]

number

[0117] In the above equation (29), since the numerator on the right-hand side has either a "+ (plus)" or a "- (minus)", it can be considered in two ways: the relational equation between coefficient a1 and coefficient b1 when the numerator on the right-hand side is "+ (plus)" (equation (30) below), and the relational equation between coefficient a2 and coefficient b2 when the numerator on the right-hand side is "- (minus)" (equation (31) below).

[0118]

number

[0119]

number

[0120] If the relationship between the coefficient a and the coefficient b satisfies either the above equation (30) or the above equation (31), then in the AC generating circuit 42, the resonant frequency ωs when the capacitors C10 and C20 are connected in series will be equal to the resonant frequency ωp when the capacitors C10 and C20 are connected in parallel (as shown in the following equation (32)).

[0121]

number

[0122] However, while the coefficient a1 in the above equation (30) is always positive, the coefficient a2 in the above equation (31) can be negative. If the coefficient a2 is negative, the AC generating circuit 42 will not function properly. Therefore, in order for the coefficient a2 to be positive (to satisfy the following equation (33)), the numerator on the right side of the above equation (31) must be positive. That is, the range that the coefficient b2 can take in the above equation (31) must satisfy a specific condition, such as the range expressed by the following equation (34). However, even if the above equation (31) does not hold true for the relationship between the coefficients a and b, as long as the above equation (30) holds true, the resonant frequency ωs when the capacitors C10 and C20 are connected in series in the AC generating circuit 42 and the resonant frequency ωp when the capacitors C10 and C20 are connected in parallel will at least once match (to satisfy the above equation (32)).

[0123]

number

[0124]

number

[0125] Taking this into consideration, the solution to the quadratic equation expressed by the above equation (13), that is, the resonant frequency ωs when the capacitors C10 and C20 are connected in series in the AC generating circuit 42, can be obtained in two ways, as shown in the following equation (35): the resonant frequency ωs1 when the numerator on the right-hand side is “+ (plus)”, and the resonant frequency ωs2 when the numerator on the right-hand side is “- (minus)”.

[0126]

number

[0127] Even in this case, the resonant frequency ωs1 always exists, but the resonant frequency ωs2 has the relationship between the coefficient a and the coefficient b as shown in the following equation (36), and if the following equation (37) holds in the numerator of the right-hand side of the above equation (35), the numerator of the right-hand side of the above equation (35) becomes the following equation (38), which exists. In other words, if the following equation (38) holds in the numerator of the right-hand side of the above equation (35), the following equation (39) holds, and there are two resonant frequencies ωs when the capacitors C10 and C20 are connected in series in the AC generating circuit 42: the resonant frequency ωs1 and the resonant frequency ωs2.

[0128]

number

[0129]

number

[0130]

number

[0131]

number

[0132] On the other hand, the solution of the quadratic equation expressed by the above equation (20), that is, the resonant frequency ωp when the capacitors C10 and C20 are connected in parallel in the AC generating circuit 42, can be obtained in two ways, as shown in the following equation (40): the resonant frequency ωp1 when the numerator on the right-hand side is “+ (plus)”, and the resonant frequency ωp2 when the numerator on the right-hand side is “- (minus)”.

[0133]

number

[0134] In this case as well, the resonant frequency ωp1 always exists, but since the relationship between the coefficient a and the coefficient b is that of the above equation (36), just as in the case where the capacitors C10 and C20 are connected in series, if the following equation (41) holds in the numerator of the right-hand side of the above equation (40), the numerator of the right-hand side of the above equation (40) becomes the following equation (42), which exists. In other words, even when the capacitors C10 and C20 are connected in parallel in the AC generating circuit 42, if the following equation (41) holds in the numerator of the right-hand side of the above equation (40), the result becomes the following equation (43), and two resonant frequencies ωp exist: the resonant frequency ωp1 and the resonant frequency ωp2.

[0135]

number

[0136]

number

[0137]

number

[0138] [Example of resonant frequency of AC current] Here, an example of the resonant frequency ω of the AC current generated by the AC generating circuit 42 will be described. Fig. 6 is an example of an equivalent circuit for explaining the resonant frequency ω of the AC current generated in the AC generating circuit 42 of the embodiment. Fig. 6 shows an equivalent circuit in the case where a predetermined AC voltage is supplied to the AC generating circuit 42 from an AC power source E1 in place of the power storage unit Ba in the battery 30. Fig. 6(a) shows an equivalent circuit in the case where capacitors C10 and C20 are connected in series, and Fig. 6(b) shows an equivalent circuit in the case where capacitors C10 and C20 are connected in parallel.

[0139] Here, an example will be described in which the resonant frequency ω of the AC current to be generated, more specifically, the resonant frequencies ωs1 and ωp1 of the AC current to be generated, are set to 200 [kHz] in each equivalent circuit shown in Fig. 6. Here, it is assumed that the resistance component Rs of the resistance Ra and the inductance component Ls of the inductance La of the battery 30 are, for example, values ​​shown in the following equation (44). Furthermore, it is assumed that the coefficient b is set as shown in the following equation (45).

[0140]

number

[0141]

number

[0142] In this case, the coefficient a can be calculated based on the above equation (30) as shown in the following equation (46).

[0143]

number

[0144] As a result, the inductance Lx of the inductor L10 and the inductor L20 can be calculated based on the above equation (12) as shown in the following equation (47).

[0145]

number

[0146] Furthermore, the capacitance Cy of the capacitors C11 and C21 can be calculated based on the above equation (35) as shown in the following equation (48): The capacitance Cy may also be calculated based on the above equation (40).

[0147]

number

[0148] Then, the capacitance Cx of the capacitors C10 and C20 can be calculated based on the above equation (12) as shown in the following equation (49).

[0149]

number

[0150] In this way, the values ​​(parameters) of the coefficient a, inductance Lx, capacitance Cy, and capacitance Cx can be calculated based on the provisionally set coefficient b (here, coefficient b=2.5). Then, the AC generating circuit 42 is configured with components (capacitor C10, capacitor C11, capacitor C20, capacitor C21, inductor L10, inductor L20) adjusted (determined) to the calculated values. This makes it possible to realize the AC generating circuit 42 in which at least the resonant frequency ωs1 generated when capacitors C10 and C20 are connected in series is equal to (matches) the resonant frequency ωp1 generated when capacitors C10 and C20 are connected in parallel. More specifically, when the capacitors C10 and C20 are connected in series, an AC generating circuit 42 can be realized which generates the resonant frequencies ωs1 and ωs2 that can be calculated as shown in the following equation (50) based on the above equation (35), and when the capacitors C10 and C20 are connected in parallel, it can be realized which generates the resonant frequencies ωp1 and ωp2 that can be calculated as shown in the following equation (51) based on the above equation (40).

[0151] In the calculations of the following equations (50) and (51), the angular frequency expressed as the resonant frequency ω in the above equations (35) and (40), respectively, is expressed as the normal frequency f as in the following equations (52) and (53).

[0152]

number

[0153]

number

[0154]

number

[0155]

number

[0156] As can be seen from the calculation results of the above equations (50) and (51), when capacitors C10 and C20 are connected in series, two resonant frequencies ω exist: resonant frequency ωs1 (= frequency fs1) ​​and resonant frequency ωs2 (= frequency fp2). When capacitors C10 and C20 are connected in parallel, two resonant frequencies ω exist: resonant frequency ωp1 (= frequency fp1) and resonant frequency ωp2 (= frequency fp2). In this case, frequencies fs1 and fp1 are equal at 200 kHz. In other words, there is at least one match between the resonant frequency ωs when capacitors C10 and C20 are connected in series and the resonant frequency ωp when capacitors C10 and C20 are connected in parallel.

[0157] FIG. 7 is a diagram showing an example of the frequency characteristics (simulation characteristics) of the AC current generated in the AC generating circuit 42 of the embodiment. The example of the frequency characteristics shown in FIG. 7 is an example in which each component of each equivalent circuit shown in FIG. 6 is adjusted to the value calculated by the above equations (44) to (49). FIG. 7 shows an example of the amplitude of the AC current when an AC voltage with an amplitude of 1 [V] is supplied from the AC power supply E1. FIG. 7(a) shows an example of the frequency characteristics when the capacitors C10 and C20 are connected in series, and FIG. 7(b) shows an example of the frequency characteristics when the capacitors C10 and C20 are connected in parallel. In FIGS. 7(a) and 7(b), the horizontal axis represents frequency, and the vertical axis represents the current value of the generated AC current. The vertical axis represents the amplitude of the generated AC current.

[0158] As shown in FIGS. 7A and 7B, in both the case where capacitors C10 and C20 are connected in series and the case where they are connected in parallel, there are two resonance points where the current value peaks, which indicates that there are two different resonance frequencies ω. More specifically, in the example of frequency characteristics when capacitors C10 and C20 are connected in series shown in FIG. 7A, it can be seen that there are resonance points where the current value peaks at frequencies fs1 and fs2 calculated using equation (50) above. On the other hand, in the example of frequency characteristics when capacitors C10 and C20 are connected in parallel shown in FIG. 7B, it can be seen that there are resonance points where the current value peaks at frequencies fp1 and fp2 calculated using equation (51) above. This also indicates that an AC generating circuit 42 with two different resonance frequencies ω can be realized by configuring the circuit using components adjusted (determined) to the values ​​calculated using equations (44) to (49) above.

[0159] In this way, the AC generating circuit 42 is configured with the capacitors C10, C11, C20, C21, inductor L10, and inductor L20, each having the coefficient a calculated based on the provisionally set coefficient b, the inductance Lx, the capacitance Cy, and the capacitance Cx (parameters). As a result, the AC generating circuit 42 can achieve a configuration in which the frequencies f are equal (match) for at least one of the frequency fs1 when the capacitors C10 and C20 are connected in series and the frequency fp1 when the capacitors C10 and C20 are connected in parallel.

[0160] In the AC generating circuit 42, for example, when the battery 30 mounted on the vehicle 1 is configured as a combination of multiple batteries 30, by connecting the AC generating circuit 42 to each battery 30 and providing a predetermined phase difference between the waveforms of the AC currents generated by the respective AC generating circuits 42, it is possible to reduce overall voltage fluctuations when the temperature of the battery 30 is raised. In other words, by shifting the phases of the current waveforms of the AC currents generated by the respective AC generating circuits 42 by a predetermined phase between the respective AC generating circuits 42, it is possible to reduce overall voltage fluctuations when the temperature of the battery 30 is raised. For example, when the battery 30 mounted on the vehicle 1 is configured as a combination of two batteries 30, by shifting the phases of the current waveforms of the AC currents generated by the respective AC generating circuits 42 connected to the respective batteries 30 by 180°, it is possible to reduce overall voltage fluctuations when the temperature of each battery 30 is raised. For example, if the battery 30 mounted on the vehicle 1 is a combination of three batteries 30, the phases of the current waveforms of the AC currents generated by the AC generating circuits 42 connected to each battery 30 can be shifted by 120° to reduce the overall voltage fluctuation when raising the temperature of each battery 30. This is because the current waveforms of the AC currents generated by the AC generating circuits 42 are nearly sinusoidal and symmetrical between positive and negative current values. This allows the temperature raising device 40 to efficiently raise the temperature of the battery 30.

[0161] [Operation of the heating device] Next, an example of the operation of the temperature raising device 40 will be described. Here, a case will be described in which the battery 30 mounted on the vehicle 1 is configured as a combination of two batteries 30 (battery 30a and battery 30b). In this case, an AC generating circuit 42 is connected to each battery 30, and the generated AC current is applied (flowed) to raise the temperature. At this time, the control unit 44 controls the AC currents generated by each AC generating circuit 42 to be shifted in phase by a predetermined phase (here, shifted by 180°), thereby reducing the overall voltage fluctuation (so-called ripple in the voltage waveform) output by the pair of two batteries 30. In other words, the control unit 44 shifts the timing of the control signal CS and inputs it to each AC generating circuit 42 so that each AC generating circuit 42 operates inversely, thereby reducing the overall voltage fluctuation when raising the temperature of the two batteries 30. Battery 30a is an example of a "first power storage body," and battery 30b is an example of a "second power storage body."

[0162] [Operation of the temperature raising device of the comparative example] First, for comparison with the operation of the temperature raising device 40, the operation of a temperature raising device (hereinafter referred to as "temperature raising device 40C") employing an AC generating circuit 42C of a comparative example shown in Fig. 4 will be described. Fig. 8 is a diagram showing an example of the configuration and operating waveforms (simulation waveforms) of the temperature raising device 40C employing the AC generating circuit 42C of the comparative example. Fig. 8 shows an example in which the resonant frequency ω of the AC current generated by the AC generating circuit 42C is set to 200 [kHz].

[0163] 8(a) shows the connection of the AC generating circuits 42C (AC generating circuit 42Ca and AC generating circuit 42Cb) corresponding to each battery 30, and the AC current flowing through each battery 30 to which each AC generating circuit 42C is connected. FIG. 8(b) shows an example of control signals output by the control unit 44 to each switch, and changes in the AC current and output voltage within each battery 30. In FIG. 8, the "a" added to the end of each symbol indicates that it corresponds to the AC generating circuit 42Ca, and the "b" indicates that it corresponds to the AC generating circuit 42Cb.

[0164] As shown in FIG. 8(a), in a configuration in which two batteries 30 are combined, an AC generating circuit 42Ca is connected to one battery 30a, and an AC generating circuit 42Cb is connected to the other battery 30b. The control unit 44 outputs control signals to switches included in each AC generating circuit 42C so that the AC currents generated by the respective AC generating circuits 42C are 180° out of phase with each other. FIG. 8(a) shows an example of voltage measurement positions and current flow directions that change in each battery 30 as a result of the control unit 44 controlling each switch using the control signal. More specifically, as an example of the voltage and current corresponding to the AC generating circuit 42Ca, the voltage V1-V0 between the two electrodes of the battery 30a (including the inductance Laa) and the current I-E1a flowing through the battery 30a (including the inductance Laa) are shown. Furthermore, as examples of the voltage and current corresponding to the AC generating circuit 42Cb, the voltage V2-V1 between the two poles of the battery 30b (including the inductance Lab) and the current I-E1b flowing through the battery 30b (including the inductance Lab) are shown, respectively. Also, Fig. 8(a) shows the voltage V2-V0 across one end (V0) on the negative side of the battery 30a in the AC generating circuit 42Ca and one end (V2) on the positive side of the battery 30b in the AC generating circuit 42Cb as the total voltage of the combined battery 30a and battery 30b.

[0165] FIG. 8B shows an example of control signals CS used by the control unit 44 to control each AC generating circuit 42C, and changes in current and voltage in the AC generating circuit 42Ca and the AC generating circuit 42Cb. In FIG. 8B, the control unit 44 sets each control signal CS to a "High" level to turn the corresponding switch on, and to a "Low" level to turn the corresponding switch off. In FIG. 8B, the control unit 44 outputs the control signal CS to each switch with a duty ratio of 1:1, i.e., a duty ratio of 50%. As described above, the control unit 44 may provide a dead time between the period when the switch is on and the period when the switch is off, during which all switches are off. However, FIG. 8B shows a case in which the control unit 44 controls each switch without providing a dead time.

[0166] Fig. 8(b) shows an example of the changes in voltage V1-V0 and current I-E1a that occur when the control unit 44 controls the AC generating circuit 42Ca with control signals CS1a, CS2a, and CS3a. Fig. 8(b) also shows an example of the changes in voltage V2-V1 and current I-E1b that occur when the control unit 44 controls the AC generating circuit 42Cb with control signals CS1b, CS2b, and CS3b. Fig. 8(b) also shows an example of the change in voltage V2-V0.

[0167] As shown in FIG. 8(b), during a period P1, the control unit 44 sets the control signals CS1a and CS2a of the AC generating circuit 42Ca to a "Low" level and sets the control signal CS3a to a "High" level. As a result, in the AC generating circuit 42Ca, the capacitors C1a and C2a are connected in series to the battery 30a, and the current I-E1a flows mainly in the positive region. As a result, the voltages V1-V0 of the AC generating circuit 42Ca decrease mainly from positive peak voltages toward negative peak voltages. Then, as shown in FIG. 8(b), during a period P2, the control unit 44 sets the control signals CS1a and CS2a of the AC generating circuit 42Ca to a "High" level and sets the control signal CS3a to a "Low" level. As a result, in the AC generating circuit 42Ca, the capacitors C1a and C2a are connected in parallel to the battery 30a, and the current I-E1a flows mainly in the negative region. As a result, the voltages V1-V0 of the AC generating circuit 42Ca rise mainly from negative peak voltages toward positive peak voltages.

[0168] As shown in FIG. 8B, in the AC generating circuit 42Cb, the control unit 44 controls the control signals CS1b, CS2b, and CS3b during periods P1 and P2. As a result, the current I-E1b flows in the AC generating circuit 42Cb, just like in the AC generating circuit 42Ca. However, as described above, the control unit 44 outputs the control signals CS so that the AC currents generated by the AC generating circuits 42C are 180° out of phase with each other. Therefore, the current I-E1b flowing in the battery 30b connected to the AC generating circuit 42Cb is 180° out of phase with the current I-E1a flowing in the battery 30a connected to the AC generating circuit 42Ca. As a result, the voltage V2-V1 of the AC generating circuit 42Cb is also 180° out of phase with the voltage V1-V0 of the AC generating circuit 42Ca.

[0169] In this way, in the temperature raising device 40C, the control unit 44 outputs the control signal CS to each switch, and as shown in FIG. 8(b), the voltage V2-V0 is the sum of the voltage V1-V0 of the AC generating circuit 42Ca and the voltage V2-V1 of the AC generating circuit 42Cb. However, as can be seen from the waveform of voltage V2-V0 shown in FIG. 8(b), although the amplitude is narrower than the amplitudes of voltage V1-V0 and voltage V2-V1, the voltage waveform is not nearly sinusoidal. This is because the control unit 44 switches the connection of capacitors C1 and C2 to the battery 30 between a series connection and a parallel connection. At this time, the current waveforms of the AC currents (currents I-E1a and I-E1b) generated by the AC generating circuits 42C are not sinusoidal, and the amplitudes also differ between the positive and negative regions of the AC current, i.e., the AC currents are asymmetrical. In this case, the overall voltage fluctuation (ripple in the voltage waveform) when the temperature of the battery 30 is increased cannot be sufficiently reduced.

[0170] Incidentally, in the AC generating circuit 42C, as described above, the resonant frequency ωs when the capacitors C1 and C2 are connected in series is twice the resonant frequency ωp when the capacitors C1 and C2 are connected in parallel. For this reason, it is considered preferable that the control unit 44 set the duty ratio to 1:2 and switch the connection of the capacitors C1 and C2 of each AC generating circuit 42C to the battery 30 between a series connection and a parallel connection.

[0171] [Another operation of the temperature raising device of the comparative example] Fig. 9 is a diagram showing another example of operating waveforms (simulation waveforms) of a temperature raising device 40C employing an AC generating circuit 42C of a comparative example. Fig. 9 shows an example in which, in the configuration shown in Fig. 8(a), the control unit 44 switches between series connection and parallel connection of the capacitors C1 and C2 in each AC generating circuit 42C to the battery 30 at a duty ratio of 1:2. Fig. 9 also shows an example in which the resonant frequency ω of the AC current generated by the AC generating circuit 42C is set to 200 [kHz].

[0172] 8(b), Fig. 9 shows an example of each control signal CS used by the control unit 44 to control each AC generating circuit 42C, and changes in current and voltage in the AC generating circuit 42Ca and the AC generating circuit 42Cb. In Fig. 9, too, the letter "a" added to the end of each symbol indicates that it corresponds to the AC generating circuit 42Ca shown in Fig. 8(a), and the letter "b" indicates that it corresponds to the AC generating circuit 42Cb shown in Fig. 8(a).

[0173] As shown in FIG. 9, during a period PSa, the control unit 44 sets the control signals CS1a and CS2a of the AC generating circuit 42Ca to a "Low" level and sets the control signal CS3a to a "High" level. As a result, in the AC generating circuit 42Ca, the capacitors C1a and C2a are connected in series to the battery 30a, and the current I-E1a flows mainly in the positive region, as in FIG. 8(b). As a result, the voltages V1-V0 of the AC generating circuit 42Ca decrease mainly from positive peak voltages toward negative peak voltages, as in FIG. 8(b). Thereafter, during a period PPa, the control unit 44 sets the control signals CS1a and CS2a of the AC generating circuit 42Ca to a "High" level and sets the control signal CS3a to a "Low" level. As a result, in the AC generating circuit 42Ca, the capacitors C1a and C2a are connected in parallel to the battery 30a, and the current I-E1a flows mainly in the negative region, as in FIG. 8(b). As a result, the voltages V1-V0 of the AC generating circuit 42Ca rise mainly from negative peak voltages toward positive peak voltages, similar to FIG. 8(b).

[0174] As shown in FIG. 9, in the AC generating circuit 42Cb, the control unit 44 controls the control signals CS1b, CS2b, and CS3b during the periods PSb and PPb. As a result, the current I-E1b flows in the AC generating circuit 42Cb, similar to the AC generating circuit 42Ca. At this time, the control unit 44 also outputs the control signals CS so that the AC currents generated by the AC generating circuits 42C are 180° out of phase with each other, as described above. Therefore, as in FIG. 8(b), the current I-E1b flowing in the battery 30b connected to the AC generating circuit 42Cb is 180° out of phase with the current I-E1a flowing in the battery 30a connected to the AC generating circuit 42Ca. As a result, the voltage V2-V1 of the AC generating circuit 42Cb is 180° out of phase with the voltage V1-V0 of the AC generating circuit 42Ca, similar to FIG. 8(b).

[0175] In this way, in the temperature raising device 40C, the control unit 44 outputs the control signal CS to each switch at a duty ratio of 1:2, so that the voltage V2-V0 is the sum of the voltage V1-V0 of the AC generating circuit 42Ca and the voltage V2-V1 of the AC generating circuit 42Cb, as shown in FIG. 8(b). However, as can be seen from the waveform of the voltage V2-V0 shown in FIG. 9, the voltage waveform does not approximate a sine wave, as shown in FIG. 8(b). This is because even if the control unit 44 switches the connection of the capacitors C1 and C2 to the battery 30 between a series connection and a parallel connection at a duty ratio of 1:2 to match the resonant frequencies ωs and ωp, the current waveforms of the currents I-E1a and I-E1b generated by the AC generating circuits 42C do not become sine waves, and the amplitude of the AC currents still differs between the positive and negative regions (they become asymmetric between positive and negative). For this reason, as shown in FIG. 9, even if the control unit 44 sets the duty ratio to 1:2 and switches the connection of the capacitors C1 and C2 of each AC generating circuit 42C to the battery 30 between a series connection and a parallel connection, it is not possible to sufficiently reduce the overall voltage fluctuation (ripple in the voltage waveform) when the temperature of the battery 30 is increased.

[0176] Next, the operation of the temperature raising device 40 will be described. Fig. 10 is a diagram showing an example of the configuration and operating waveforms (simulation waveforms) of the temperature raising device 40 employing the AC generating circuit 42 of the embodiment. Fig. 10 shows an example in which the values ​​(parameters) of the components included in the AC generating circuit 42 are adjusted to the values ​​calculated by the above equations (44) to (49), and the resonant frequency ω of the AC current generated by the AC generating circuit 42 is set to 200 [kHz], similar to the example of the operating waveform of the AC generating circuit 42C of the comparative example shown in Fig. 8.

[0177] FIG. 10(a) shows the connection of the AC generating circuits 42 (AC generating circuit 42a and AC generating circuit 42b) corresponding to each battery 30, and the AC current flowing through each battery 30 to which each AC generating circuit 42 is connected. FIG. 10(b) shows an example of control signals output by the control unit 44 to each switch, and the AC current and output voltage changes in each battery 30. In FIG. 10, the letter "a" at the end of each symbol indicates that it corresponds to the AC generating circuit 42a, and the letter "b" indicates that it corresponds to the AC generating circuit 42b. The AC generating circuit 42a is an example of an "AC generating circuit," and the AC generating circuit 42b is an example of a "second AC generating circuit." The AC current generated by the AC generating circuit 42a is an example of an "AC current," and the AC current generated by the AC generating circuit 42b is an example of a "second AC current."

[0178] As shown in FIG. 10(a), in a configuration in which two batteries 30 are combined, an AC generating circuit 42a is connected to one battery 30a, and an AC generating circuit 42b is connected to the other battery 30b. The control unit 44 outputs control signals to switches included in each AC generating circuit 42 so that the AC currents generated by each AC generating circuit 42 are 180° out of phase with each other. FIG. 10(a) shows an example of voltage measurement positions and current flow directions that change in each battery 30 as a result of the control unit 44 controlling each switch with the control signal. More specifically, as an example of the voltage and current corresponding to the AC generating circuit 42a, the voltage V1-V0 between the two poles of the battery 30a (including the inductance Laa) and the current I-E1a flowing through the battery 30a (including the inductance Laa) are shown. 10(a) shows the voltage V2-V1 between the two poles of battery 30b (including inductance Lab) and the current I-E1b flowing through battery 30b (including inductance Lab) as examples of the voltage and current corresponding to AC generating circuit 42b. Also, Fig. 10(a) shows the voltage V2-V0 across one end (V0) of the negative electrode side of battery 30a in AC generating circuit 42a and one end (V2) of the positive electrode side of battery 30b in AC generating circuit 42b as the total voltage of battery 30a and battery 30b combined.

[0179] FIG. 10(b) shows an example of control signals CS used by the control unit 44 to control each AC generating circuit 42, and changes in current and voltage in the AC generating circuit 42a and the AC generating circuit 42b. In FIG. 10(b), the control unit 44 sets each control signal CS to a "High" level to turn the corresponding switch on, and to a "Low" level to turn the corresponding switch off. As described above, in the AC generating circuit 42, the resonant frequency ωs when capacitors C10 and C20 are connected in series is set equal to the resonant frequency ωp when capacitors C10 and C20 are connected in parallel. Therefore, in FIG. 10(b), the control unit 44 outputs the control signal CS to each switch with a duty ratio of 1:1, i.e., a duty ratio of 50%. As described above, the control unit 44 may provide a dead time for turning all the switches off between the period when the switches are turned on and the period when the switches are turned off. However, FIG. 10(a) shows a case where the control unit 44 controls each switch without providing a dead time.

[0180] Figure 10(b) shows an example of the changes in voltage V1-V0 and current I-E1a that occur when the control unit 44 controls the AC generating circuit 42a with control signals CS11a, CS12a, and CS13a. Figure 10(b) also shows an example of the changes in voltage V2-V1 and current I-E1b that occur when the control unit 44 controls the AC generating circuit 42b with control signals CS11b, CS12b, and CS13b. Figure 10(b) also shows an example of the change in voltage V2-V0.

[0181] As shown in FIG. 10(b), during period P1, the control unit 44 sets the control signals CS11a and CS12a of the AC generating circuit 42a to a "Low" level and sets the control signal CS13a to a "High" level. As a result, in the AC generating circuit 42a, capacitors C10a and C20a are connected in series to the battery 30a, and current I-E1a flows mainly in the negative region. As a result, voltage V1-V0 of the AC generating circuit 42a increases mainly from negative peak voltages toward positive peak voltages. Meanwhile, during period P1, the control unit 44 sets the control signals CS11b and CS12b of the AC generating circuit 42b to a "High" level and sets the control signal CS13b to a "Low" level. As a result, in the AC generating circuit 42b, capacitors C10b and C20b are connected in parallel to the battery 30a, and current I-E1b flows mainly in the positive region. As a result, the voltage V2-V1 of the AC generating circuit 42b drops mainly from a positive peak voltage toward a negative peak voltage.

[0182] 10(b), during a period P2, the control unit 44 sets the control signals CS11a and CS12a of the AC generating circuit 42a to a "High" level and sets the control signal CS13a to a "Low" level. As a result, in the AC generating circuit 42a, the capacitors C10a and C20a are connected in parallel to the battery 30a, and the current I-E1a flows mainly in the positive region. As a result, the voltage V1-V0 of the AC generating circuit 42a decreases mainly from a positive peak voltage to a negative peak voltage. Meanwhile, during a period P2, the control unit 44 sets the control signals CS11b and CS12b of the AC generating circuit 42b to a "Low" level and sets the control signal CS13b to a "High" level. As a result, in the AC generating circuit 42b, the capacitors C10b and C20b are connected in series to the battery 30a, and the current I-E1b flows mainly in the negative region. As a result, the voltage V2-V1 of the AC generating circuit 42b rises mainly from a negative peak voltage toward a positive peak voltage.

[0183] In this way, as described above, the control unit 44 outputs the control signals CS so that the phases of the AC currents generated by the AC generating circuits 42 are shifted by 180°. As a result, the current I-E1a flowing in the battery 30a connected to the AC generating circuit 42a and the current I-E1b flowing in the battery 30b connected to the AC generating circuit 42b are shifted by 180°. As a result, the voltage V1-V0 of the AC generating circuit 42a and the voltage V2-V1 of the AC generating circuit 42b are also shifted by 180°.

[0184] In this manner, in the temperature raising device 40, the control unit 44 outputs a control signal CS with a duty ratio of 50% to each switch to switch the connection of capacitors C10 and C20 to the battery 30 between a series connection and a parallel connection, causing current I-E1a to flow in the battery 30a connected to the AC generating circuit 42a, and current I-E1b to flow in the battery 30b connected to the AC generating circuit 42b. Furthermore, as can be seen from the waveforms of current I-E1a and current I-E1b shown in FIG. 10(b), the waveforms of the respective AC currents are more sinusoidal than the waveforms of the AC currents (current I-E1a and current I-E1b) generated by the respective AC generating circuits 42 in the temperature raising device 40C shown in FIG. 8. As a result, in the temperature raising device 40, the voltage V1-V0 of the AC generating circuit 42a and the voltage V2-V1 of the AC generating circuit 42b are symmetrical in terms of positive and negative. As a result, in the temperature raising device 40, the voltage waveform of voltage V2-V0, which is the sum of voltages V1-V0 and V2-V1, as can be seen from the waveform of voltage V2-V0 shown in Fig. 10(b), has much less voltage fluctuation (ripple in the voltage waveform) than voltage V2-V0 in the temperature raising device 40C shown in Fig. 8. In other words, in the temperature raising device 40, there is almost no fluctuation in voltage V2-V0, and it can be said to have a flat characteristic.

[0185] Thus, in the temperature raising device 40, when the battery 30 mounted on the vehicle 1 is configured as a combination of two batteries 30 (here, batteries 30a and 30b), the control unit 44 outputs a control signal CS with a duty ratio of 50% to each switch to switch between a series connection and a parallel connection of the capacitors C10 and C20 to the battery 30. In other words, the control unit 44 outputs and controls the control signal CS with a predetermined phase shift (here, a 180° phase shift) so that the AC generating circuits 42 corresponding to each battery 30 operate in opposite directions. As a result, the AC generating circuits 42 can reduce fluctuations in the total voltage V2-V0 of the combined two batteries 30, as shown in FIGS. 10(b), 12(a), and 12(b). In other words, the AC generating circuits 42 can generate AC current with reduced harmonic components, thereby reducing noise emitted when raising the temperature of the battery 30. For this reason, when the battery 30 mounted on the vehicle 1 is configured as a combination of two batteries 30, the AC generating circuit 42 is more easily applicable as a configuration that applies (passes) AC current to each battery 30 to raise its temperature and reduces fluctuations in the overall voltage output by the set of two batteries 30 (so-called ripple in the voltage waveform).

[0186] [Another configuration of the heating device] FIG. 10(a) shows an example of the configuration of the temperature raising device 40 when the battery 30 mounted on the vehicle 1 is a combination of two batteries 30 (here, battery 30a and battery 30b), but as described above, the battery 30 mounted on the vehicle 1 may be a combination of three batteries 30. FIG. 11 is a diagram showing another example of the configuration of the temperature raising device 40 that employs the AC generating circuit 42 of the embodiment. FIG. 11 shows an example of the configuration when the battery 30 mounted on the vehicle 1 is a combination of three batteries 30 (battery 30a, battery 30b, and battery 30c).

[0187] 11, in a configuration in which three batteries 30 are combined, an AC generating circuit 42a is connected to the first battery 30a, an AC generating circuit 42b is connected to the second battery 30b, and an AC generating circuit 42c is connected to the third battery 30c. Then, the control unit 44 outputs control signals to switches provided in each AC generating circuit 42 so that the phases of the AC currents generated by the respective AC generating circuits 42 are shifted by 120°.

[0188] In this case, the control of each AC generating circuit 42 by the control unit 44 (output timing of each control signal CS) should be equivalent to the control of each AC generating circuit 42 by the control unit 44 (output timing of each control signal CS) in the case where the battery 30 is configured as a combination of two batteries 30, as described using Fig. 10. As a result, the operation of each AC generating circuit 42 (changes in current and voltage) can be easily considered from the operation of each AC generating circuit 42 (changes in current and voltage) described using Fig. 10. Therefore, detailed description of the control of each AC generating circuit 42 by the control unit 44 and the operation of each AC generating circuit 42 in the configuration shown in Fig. 11 will be omitted.

[0189] As described above, according to the temperature raising device 40 of the embodiment, the AC generating circuit 42 includes, for example, capacitors C10, C11, C20, C21, switches S11, S12, S13, inductor L10, and inductor L20. In the temperature raising device 40 of the embodiment, the connection of capacitors C10 and C20 included in the AC generating circuit 42 to the battery 30 is switched between a series connection and a parallel connection, thereby generating an AC current based on the power stored in the battery 30 by utilizing a resonance operation in which magnetic energy stored in inductance La of the battery 30 is alternately exchanged with electrostatic energy stored in at least capacitor C10. In this case, in the AC generating circuit 42 of the embodiment, the values ​​(parameters) of the components of the capacitors C10, C11, C20, C21, and inductors L10 and L20 are adjusted (determined) to values ​​calculated based on the relational expressions (the above expressions (12), (29) to (31), (35), and (40)) including the inductance component Ls of the inductance La of the battery 30. As a result, in the temperature raising device 40 of the embodiment, the resonant frequencies ω of the AC currents are equal (matched) when the capacitors C10 and C20 are connected in series to the battery 30 and when they are connected in parallel to the battery 30, and the AC generating circuits 42 can generate AC currents whose waveforms are closer to sine waves. As a result, in the temperature raising device 40 of the embodiment, the AC generating circuits 42 generate AC currents whose waveforms are closer to sine waves, thereby enabling the battery 30 to be heated more efficiently. As a result, in the vehicle 1 employing the heating device 40 of the embodiment, the battery 30 can be used in a state where it has been heated to a suitable temperature, thereby suppressing a decrease in the charge / discharge performance of the battery 30. Furthermore, in the vehicle 1 employing the heating device 40 of the embodiment, the AC current generated by the AC generating circuit 42 contains fewer harmonic components, so that it is possible to reduce noise emitted when the battery 30 is heated.

[0190] In the temperature raising device 40 of the above-described embodiment, the capacitances Cx of the capacitors C10 and C20 included in the AC generating circuit 42 are equal, the capacitances Cy of the capacitors C11 and C21 are equal, and the inductances Lx of the inductors L10 and L20 are equal. The inductance component of the inductance La of the battery 30 is the inductance component Ls, and the capacitance and inductance values ​​(parameters) of each component are adjusted (determined) based on the relational expressions expressed by the above equations (12), (29) to (31), (35), and (40). However, it is expected that the capacitance and inductance characteristics of each component will vary even between the same components. Furthermore, it is expected that the wiring connecting the AC generating circuit 42 and the battery 30 will also include an inductance component. For this reason, in the temperature raising device 40 of the embodiment, the capacitance and inductance values ​​(parameters) of the components included in the AC generating circuit 42 may be set to values ​​that take into consideration variations in the characteristics of the components, variations in the inductance component Ls of the inductance La of the battery 30, and inductance components included in the wiring portion connecting the AC generating circuit 42 and the battery 30. In other words, in the temperature raising device 40 of the embodiment, the capacitance Cx of the capacitors C10 and C20, the capacitance Cy of the capacitors C11 and C21, and the inductance Lx of the inductors L10 and L20 may have a certain degree of range, as long as the current waveform of the AC current generated by the AC generating circuit 42 is within a range that can be considered to be a sine wave (a range in which a substantial effect can be obtained). In other words, in the temperature raising device 40 of the embodiment, the capacitances Cx of the capacitors C10 and C20 provided in the AC generating circuit 42 are set to values ​​within a range that can be said to be equal, the capacitances Cy of the capacitors C11 and C21 are set to be equal, and the inductances Lx of the inductors L10 and L20 are set to be equal.

[0191] In the temperature raising device 40 of the embodiment described above, the control unit 44 outputs the control signal CS to each switch with a duty ratio of 50%. However, as described above, the control unit 44 may control the switches by providing a dead time during which all switches are in a non-conductive state between a period during which the switches are in a conductive state and a period during which the switches are in a non-conductive state. For example, in the temperature raising device 40 of the embodiment, the control unit 44 may provide a dead time by setting the duty ratio of the control signal CS output to each switch to a value that can be considered to be approximately 50% (e.g., a predetermined value between 45% and 55%), and output the control signal CS to each switch to switch the connection of the capacitors C10 and C20 to the battery 30 from a parallel connection to a series connection, or vice versa.

[0192] According to the temperature raising device 40 of the embodiment described above, the AC generating circuit 42 raises the temperature of the battery 30 by generating an AC current based on the power stored in the battery 30 having an inductance La, and includes a capacitor C10 having a first terminal connected to the positive electrode side of the battery 30, a capacitor C20 having a second terminal connected to the negative electrode side of the battery 30, a parallel switch unit (for example, switches S11 and S12) that connects the second terminal of the capacitor C10 to the second terminal of the capacitor C20 and connects the first terminal of the capacitor C10 to the first terminal of the capacitor C20, thereby connecting the capacitors C10 and C20 in parallel to the battery 30, and The vehicle 1 includes a series switch unit (e.g., switch S13) that connects the capacitor C10 and the capacitor C20 in series to the battery 30 by connecting the first end of the capacitor C20 to the first end of the capacitor C20, an inductor L10 connected between the positive electrode side of the battery 30 and the first end of the capacitor C10, an inductor L20 connected between the second end of the capacitor C20 and the negative electrode side of the battery 30, a capacitor C11 connected between the second end of the capacitor C10 and the negative electrode side of the battery 30, and a capacitor C21 connected between the positive electrode side of the battery 30 and the first end of the capacitor C20. This makes it possible to more efficiently raise the temperature of the battery 30 used for traveling mounted on the vehicle 1. As a result, in the vehicle 1 that employs the temperature raising device 40 of the embodiment, the battery 30 can be used in a state where it has been heated to a suitable temperature, and deterioration in the charge / discharge performance of the battery 30 can be suppressed. As a result, in the vehicle 1 that is equipped with the temperature raising device 40 of the embodiment, the marketability of the vehicle 1 can be improved, such as by improving durability. For these reasons, the vehicle 1 equipped with the heating device 40 of the embodiment is expected to improve energy efficiency and contribute to reducing adverse effects on the global environment.

[0193] In each of the above-described embodiments, the control device 100 controls the start or stop of the temperature raising device 40, and the control unit 44 controls each switch provided in the AC generating circuit 42 to a conductive state or a non-conductive state. The operation of the control unit 44 may be realized by a hardware processor, such as a CPU provided in the control unit 44, executing a program. The function of the control device 100 may include the function of the control unit 44 described above. In this case, the control unit 44 may be omitted from the temperature raising device 40. In this case, the control device 100 is an example of a "control unit."

[0194] The above describes the form for carrying out the present invention using an embodiment, but the present invention is not limited to such an embodiment, and various modifications and substitutions can be made within the scope that does not deviate from the gist of the present invention. [Explanation of symbols]

[0195] 1. Vehicle 10. Engine 12. Motor 14...Reducer 16. Drive wheels 20 PDUs 30, 30a, 30b, 30c... Battery 32 Battery sensor 40. Heating device 42, 42a, 42b, 42c...AC generating circuit 44 Control section 70 Driving controls 80 Vehicle sensor 100 Control device C10, C10a, C10b, C10c... Capacitors C11, C11a, C11b, C11c... Capacitors C20, C20a, C20b, C20c... Capacitors C21, C21a, C21b, C21c... Capacitors S11, S11a, S11b, S11c switches S12, S12a, S12b, S12c switches S13, S13a, S13b, S13c switches L10, L10a, L10b, L10c... Inductors L20, L20a, L20b, L20c... Inductors La,Laa,Lab,Lac···Inductance Ra,Raa,Rab,Rac...Resistance Ba, Baa, Bab, Bac... Storage unit

Claims

1. An AC generating circuit that generates an AC current based on power stored in a power storage device having an inductance component to raise the temperature of the power storage device, a first capacitor having a first end connected to the positive electrode side of the power storage unit; a second capacitor having a second terminal connected to the negative electrode side of the power storage unit; a parallel switch unit that connects the second end of the first capacitor to the second end of the second capacitor and connects the first end of the first capacitor to the first end of the second capacitor, thereby connecting the first capacitor and the second capacitor in parallel to the power storage unit; a series switch unit that connects the second end of the first capacitor and the first end of the second capacitor to connect the first capacitor and the second capacitor in series to the power storage unit; a first inductor connected between the positive electrode side of the power storage unit and the first end of the first capacitor; a second inductor connected between the second end of the second capacitor and the negative electrode side of the power storage unit; a third capacitor connected between the second end of the first capacitor and the negative electrode side of the power storage unit; a fourth capacitor connected between the positive electrode side of the power storage unit and the first end of the second capacitor; An AC generating circuit comprising:

2. the inductance of the first inductor, the inductance of the second inductor, the capacitance of the first capacitor, the capacitance of the second capacitor, the capacitance of the third capacitor, and the capacitance of the fourth capacitor are The current waveform of the AC current is adjusted to be close to a sine wave based on a relational expression including the inductance component.

2. The AC generating circuit according to claim 1.

3. The relational expression is for adjusting the inductance of the first inductor, the inductance of the second inductor, the capacitance of the first capacitor, the capacitance of the second capacitor, the capacitance of the third capacitor, and the capacitance of the fourth capacitor so that the frequency of the AC current in a parallel state in which the first capacitor and the second capacitor are connected in parallel to the power storage unit matches the frequency of the AC current in a series state in which the first capacitor and the second capacitor are connected in series to the power storage unit.

3. The AC generating circuit according to claim 2.

4. The inductance of the first inductor and the inductance of the second inductor are equal.

4. The AC generating circuit according to claim 3.

5. The capacitance of the first capacitor and the capacitance of the second capacitor are equal to a first capacitance.

5. The AC generating circuit according to claim 4.

6. the capacitance of the third capacitor and the capacitance of the fourth capacitor are equal to the second capacitance; 6. The AC generating circuit according to claim 5.

7. the inductance component includes an inductance component in a wiring portion between the power storage unit and the AC generating circuit, 2. The AC generating circuit according to claim 1.

8. The parallel switch unit a first switch having a first terminal connected to the second end of the first capacitor and a second terminal connected to the second end of the second capacitor; a second switch having a first terminal connected to the first end of the first capacitor and a second terminal connected to the first end of the second capacitor; and the series switch unit includes a third switch having a first terminal connected to the first end of the second capacitor and a second terminal connected to the second end of the first capacitor, the first switch and the second switch are simultaneously controlled to a conductive state or a non-conductive state by a first control signal; the third switch is controlled to be in a conductive state or a non-conductive state by a second control signal; a first state period in which the first control signal brings the first switch and the second switch into a conductive state and a second state period in which the second control signal brings the third switch into a conductive state are non-overlapping periods.

2. The AC generating circuit according to claim 1.

9. the power storage unit includes a first power storage unit and a second power storage unit connected in series to the first power storage unit; the AC generating circuit is connected to the first power storage unit; a second AC generating circuit having the same configuration as the AC generating circuit is connected to the second power storage unit; the first control signal and the second control signal are input so as to give a predetermined phase difference between the AC current generated by the AC generating circuit and a second AC current which is an AC current generated by the second AC generating circuit; 9. The AC generating circuit according to claim 8.

10. an AC generating circuit according to claim 9; outputting the first control signal and the second control signal, and a parallel state in which the first switch and the second switch are brought into a conductive state and the third switch is brought into a non-conductive state, thereby connecting the first capacitor and the second capacitor in parallel to the power storage unit; a series state in which the first switch and the second switch are brought into a non-conductive state and the third switch is brought into a conductive state, thereby connecting the first capacitor and the second capacitor in series with the power storage unit; a control unit that alternately switches between the A heating device comprising:

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