AC generating circuit and heating device

Abstract

To provide an AC generating circuit and a temperature raising device capable of more efficiently raising the temperature of secondary batteries.SOLUTION: An AC generating circuit comprises: a first capacitor whose first end is connected with a positive electrode side of a power storage body having an inductance component; a second capacitor whose first end is connected with a negative electrode side of the power storage body; a parallel switch part that connects a second end of the first capacitor and the first end of the second capacitor to each other and connects the first end of the first capacitor and a second end of the second capacitor to each other depending on a first control signal to connect the first capacitor and the second capacitor in parallel with the power storage body; a series switch part that connects the second end of the first capacitor and the second end of the second capacitor depending on a second control signal to connect the first capacitor and the second capacitor in series with the power storage body; and an inductor connected between both terminals of the series switch part.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. For this reason, in recent years, from the viewpoint of improving the global environment, and in order to reduce CO2, there has been growing interest in electric vehicles that run at least by electric motors driven by power supplied from batteries (secondary batteries), such as hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs). The use of lithium-ion secondary batteries as batteries for in-vehicle use is being considered. In these electric vehicles, it is important to fully utilize the performance of the secondary batteries. It is known that the charge and discharge performance of secondary batteries decreases when the temperature during use falls below a moderate range. The decrease in the charge and discharge performance of secondary batteries can be suppressed by raising the temperature to a suitable temperature during use.

[0003] In this regard, for example, Patent Document 1 discloses a technology relating to a temperature raising device for raising the temperature of a secondary battery. The temperature raising device disclosed in Patent Document 1 raises the temperature of 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 decreased, 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 has been made based on the recognition of the above 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 embodiment of the present invention is an AC generating circuit that raises the temperature of a power storage body having an inductance component by generating an AC current based on power stored in the power storage body, the AC generating circuit including: a first capacitor having a first end connected to a positive electrode side of the power storage body; a second capacitor having a first end connected to a negative electrode side of the power storage body; a parallel switch unit that connects the second end of the first capacitor to the first end of the second capacitor and connects the first end of the first capacitor to the second end of the second capacitor in response to a first control signal, thereby connecting the first capacitor and the second capacitor in parallel to the power storage body; a series switch unit that connects the second end of the first capacitor to the second end of the second capacitor in response to a second control signal, thereby connecting the first capacitor and the second capacitor in series to the power storage body; and an inductor connected between both terminals of the series switch unit.

[0008] (2): 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 first 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 second end of the second capacitor, the series switch unit includes a third switch having a first terminal connected to the second end of the second capacitor and a second terminal connected to the second end of the first capacitor, and the inductor is connected in parallel between the first terminal of the third switch and the second terminal of the third switch.

[0009] (3): In the above aspect (2), the inductance of the inductor is approximately one third of the inductance component.

[0010] (4): In the above aspect (1), the parallel switch unit includes a first switch having a first terminal connected to the second end side of the first capacitor and a second terminal connected to the first 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 second end side of the second capacitor, and the series switch unit includes a third switch having a first terminal connected to the second terminal of the second switch and a second terminal connected to the second end of the first capacitor, and a third switch having a first terminal connected to the second end of the second capacitor and a second terminal connected to the second end of the first switch. and a fourth switch having a second terminal connected to a first terminal, wherein the inductor includes a first inductor having a first end connected to the first terminal of the fourth switch and a second end connected to the second terminal of the third switch, a second inductor having a first end connected to the first end of the first inductor and a second end connected between the second terminal of the second switch and the first terminal of the third switch, and a third inductor having a first end connected between the first terminal of the first switch and the second terminal of the fourth switch and a second end connected to the second end of the first inductor.

[0011] (5): In the above aspect (4), the inductance of the first inductor is approximately one third of the inductance component.

[0012] (6): In the above aspect (5), the inductance of the second inductor and the inductance of the third inductor are equal to each other.

[0013] (7): In any one of the above aspects (1) to (6), the inductance component includes an inductance component in a wiring portion between the power storage unit and the AC generating circuit.

[0014] (8): A temperature raising device according to one embodiment of the present invention includes an AC generating circuit according to any one of the above (1) to (7), and a control unit that outputs, as the first control signal, a signal of a predetermined duty ratio that brings the parallel switch unit into a conductive state or a non-conductive state, and outputs, as the second control signal, a signal of the predetermined duty ratio that brings the series switch unit into a conductive state or a non-conductive state, and alternates between a first state in which the parallel switch unit is brought into a conductive state and the series switch unit into a non-conductive state and a second state in which the parallel switch unit is brought into a non-conductive state and the series switch unit is brought into a conductive state, using the first control signal and the second control signal.

[0015] (9): In the above aspect (8), the predetermined duty ratio is approximately 50 percent. Effect of the Invention

[0016] According to the above aspects (1) to (9), the temperature of the secondary battery can be increased more efficiently, thereby improving the energy efficiency. [Brief description of the drawings]

[0017] [Figure 1] 1 is a diagram showing an example of the configuration of a vehicle in which a heating device according to an embodiment is employed; [Diagram 2] 2 is a diagram showing an example of the configuration of an AC generating circuit included in the temperature raising device according to the first embodiment. FIG. [Diagram 3] 3 is an example of an equivalent circuit of the AC generating circuit of the first embodiment. [Figure 4] FIG. 1 is a diagram illustrating an example of a configuration of an AC generating circuit of a comparative example. [Diagram 5] 4 is an example of an equivalent circuit of an AC generating circuit of a comparative example. [Figure 6] FIG. 4 is a diagram showing an example of an operational waveform of an AC generating circuit of a comparative example. [Figure 7] FIG. 11 is a diagram showing another example of the operational waveforms of the AC generating circuit of the comparative example. [Figure 8] FIG. 2 is a diagram illustrating an example of an operational waveform of the AC generating circuit according to the first embodiment. [Figure 9] FIG. 4 is a diagram showing another example of the operational waveforms of the AC generating circuit of the first embodiment. [Figure 10] FIG. 11 is a diagram showing another example of the operational waveforms of the AC generating circuit of the comparative example. [Figure 11] FIG. 11 is a diagram showing an example of the configuration of an AC generating circuit included in a temperature raising device according to a second embodiment. [Figure 12] 13 is an example of an equivalent circuit of an AC generating circuit according to a second embodiment. [Figure 13] FIG. 11 is a diagram illustrating an example of an operational waveform of the AC generating circuit according to the second embodiment. [Figure 14] FIG. 11 is a diagram showing another example of the operational waveforms of the AC generating circuit according to the second embodiment. [Figure 15] 1 is a diagram comparing characteristics of AC currents generated by AC generating circuits. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an AC generating circuit and a temperature raising device of the present invention will be described with reference to the drawings.

[0019] [Vehicle configuration] FIG. 1 is a diagram showing an example of the configuration of a vehicle in which a temperature raising device according to an embodiment is adopted. The vehicle 1 is a hybrid electric vehicle (HEV) (hereinafter, simply referred to as "vehicle") that runs by combining driving of an electric motor by electric power supplied from a battery (secondary battery) for running, or driving of an internal combustion engine using fuel such as a diesel engine or a gasoline engine as an energy source. The vehicle to which the present invention is applied may be, for example, not only a four-wheeled vehicle, but also a saddle-type two-wheeled vehicle, a three-wheeled vehicle (including a vehicle with one front wheel and two rear wheels, as well as a vehicle with two front wheels and one rear wheel), and even an assisted bicycle, or any other vehicle that runs by an electric motor driven by electric power supplied from a battery for running. The vehicle 1 may be, for example, an electric vehicle (EV) that runs by driving only an electric motor.

[0020] The vehicle 1 includes, for example, an engine 10, a motor 12, a reduction gear 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.

[0021] 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 a cylinder and pistons, an intake valve, an exhaust valve, a fuel injection device, an ignition plug, a connecting rod, a crankshaft, and the like. The engine 10 may be a rotary engine. The rotational power of the engine 10 is transmitted to a reduction gear 14.

[0022] 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 reduction gear 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 reduction gear 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.

[0023] The reduction gear 14 is, for example, a differential gear. The reduction gear 14 transmits the driving force of an axis connected to the engine 10 or the motor 12, that is, the rotational power of the engine 10 or the motor 12, to an axle connected to the drive wheels 16. The reduction gear 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 the rotational speed of the engine 10 or the motor 12 is changed according to a speed ratio (gear ratio) and transmitted to the axle. The reduction gear 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.

[0024] 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 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 the output destination of the power. In FIG. 1, the components of the PDU 20 are shown as a single unit, but this is merely an example, and the components of the PDU 20 may be distributed in the vehicle 1.

[0025] The battery 30 is a battery for driving the vehicle 1. The battery 30 includes a secondary battery, such as a lithium ion battery, that can be repeatedly charged and discharged, as an electricity 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 configured as a stationary battery 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 included in the battery 30 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 composite battery that combines a secondary battery and a capacitor, but the secondary battery may have any configuration. The battery 30 stores (charges) power introduced from a charger (not shown) external to the vehicle 1, and discharges the stored power to drive the vehicle 1. The battery 30 stores (charges) the electric power generated by the motor 12 operating as a regenerative brake and supplied via the PDU 20, and discharges the stored electric power for running (e.g., accelerating) the vehicle 1. The battery 30 has at least an inductance component.

[0026] The battery 30 is an example of a "power storage unit" in the claims, and the inductance component connected to the power storage unit of the battery 30 is an example of an "inductance component" in the claims.

[0027] 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, temperature, etc. of the battery 30 (hereinafter referred to as "battery information") to the control device 100.

[0028] The temperature raising device 40 raises the temperature of the battery 30 in response to control from the control device 100. The temperature raising device 40 includes, for example, an AC generating circuit 42 and a control unit 44.

[0029] The AC generating circuit 42 includes, for example, a first capacitor connected to the positive electrode side of the battery 30, a second capacitor connected to the negative electrode side of the battery 30, a parallel switch section that connects the first capacitor and the second capacitor in parallel to the battery 30, a series switch section that connects the first capacitor and the second capacitor in series to the battery 30, and an inductor connected between both terminals of the series switch section. The AC generating circuit 42 generates an AC current by a resonance operation between an inductance component of the battery 30 and at least the first capacitor. More specifically, the AC generating circuit 42 generates an AC current based on the power stored in the battery 30 by a resonance operation that alternately exchanges magnetic energy stored in the inductance component of the battery 30 and electrostatic energy stored in at least the first capacitor. The AC generating circuit 42 applies (passes) the generated AC current to the battery 30, thereby raising the temperature of the battery 30.

[0030] The control unit 44 switches the connection of the first capacitor and the second capacitor to the battery 30 between a parallel connection and a series connection by setting each of the parallel switch unit and the series switch unit included in the AC generating circuit 42 to a conductive state or a non-conductive state. More specifically, the control unit 44 alternately switches between a state in which the first capacitor and the second capacitor are connected in parallel to the battery 30 by setting the parallel switch unit to a conductive state and the series switch unit to a non-conductive state, and a state in which the first capacitor and the second capacitor are connected in series to the battery 30 by setting the parallel switch unit to a non-conductive state and the series switch unit to a conductive state. At this time, the control unit 44 may provide a period during which both the parallel switch unit and the series switch unit are set to a non-conductive state, that is, a so-called dead time, to switch the connection of the first capacitor and the second capacitor to the battery 30 from a parallel connection to a series connection, or vice versa.

[0031] The state in which the first capacitor and the second capacitor are connected in parallel to the battery 30 is an example of a "first state" in the claims, and the state in which the first capacitor and the second capacitor are connected in series to the battery 30 is an example of a "second state" in the claims. The temperature raising device 40 and the components included in the temperature raising device 40 will be described in detail later.

[0032] 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. Sensors are attached to driving operators 70 to detect the presence or absence of an operation of each operator by a user (driver) of vehicle 1, or the amount of operation. Driving operators 70 output the detection results of the sensors to control device 100.

[0033] 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.

[0034] The control device 100 controls the operation and behavior of the engine 10 and the motor 12 in response to the detection results output by the respective sensors provided in the driving operators 70, i.e., the operation of the respective 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.

[0035] When the vehicle 1 runs, the control device 100 controls the amount of AC power supplied from the battery 30 to the motor 12 and the frequency of the supplied AC power (i.e., the voltage waveform). At this time, the control device 100 controls the start-up of the warming device 40 based on the information on 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 start or stop of the warming device 40 so as to raise (heat) the temperature of the battery 30 to a temperature suitable for use in order to suppress a decrease in the charge / discharge performance of the battery 30.

[0036] 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 cooperation between 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-transient storage medium) such as an HDD (Hard Disk Drive) or a flash memory provided in the vehicle 1, or may be stored in a removable storage medium (non-transient storage medium) such as a DVD or a CD-ROM, and installed in the HDD or flash memory provided in the vehicle 1 by mounting the storage medium in a drive device provided in the vehicle 1.

[0037] First Embodiment [Configuration of AC generating circuit in heating device] Fig. 2 is a diagram showing an example of the configuration of an AC generating circuit 42 (hereinafter referred to as "AC generating circuit 42-1") included in the temperature raising device 40 according to the first embodiment. Fig. 2 also shows a battery 30 related to the AC generating circuit 42-1. In the battery 30, for example, a resistance Ra and an inductance La are connected in series to the positive electrode side of the 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" in the claims.

[0038] The AC generating circuit 42-1 includes, for example, a capacitor C1, a capacitor C2, a switch S1, a switch S2, a switch S3, and an inductor L3. The capacitors C1 and C2 are capacitors having the same capacitance. The switches S1, S2, and S3 are each 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) according to a control signal output by the control unit 44. In the following description, the control signal output by the control unit 44 for controlling the switch S1 to a conductive state or a non-conductive state is referred to as a "control signal CS1", the control signal for controlling the switch S2 to a conductive state or a non-conductive state is referred to as a "control signal CS2", and the control signal for controlling the switch S3 to a conductive state or a non-conductive state is referred to as a "control signal CS3".

[0039] Each of the switches S1, S2, and S3 may be a semiconductor switching element controlled to be in 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 functioning as a reflux may be further connected in parallel. When each of the switches S1, S2, and S3 is composed of 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 S1, S2, and S3 to be in a conductive or non-conductive state.

[0040] In the AC generating circuit 42-1, a first terminal of the capacitor C1 is connected to the positive electrode side of the battery 30, and a first terminal of the capacitor C2 is connected to the negative electrode side of the battery 30. Furthermore, in the AC generating circuit 42-1, a first terminal of the switch S2 is connected to the first terminal of the capacitor C1, and a second terminal of the switch S1 is connected to the first terminal of the capacitor C2. In the AC generating circuit 42-1, a first terminal of the switch S1 and a second terminal of the switch S3 are connected to the second terminal of the capacitor C1, and a second terminal of the switch S2 and a first terminal of the switch S3 are connected to the second terminal of the capacitor C2. Furthermore, in the AC generating circuit 42-1, an inductor L3 is connected in parallel between the first terminal and the second terminal of the switch S3.

[0041] With this configuration, in the AC generating circuit 42-1, the capacitors C1 and C2 are connected in parallel or in series between the positive and negative sides of the battery 30 in response to control from the control unit 44. More specifically, the control unit 44 outputs a control signal CS1 to the switch S1 for turning it on, a control signal CS2 to the switch S2 for turning it on, and a control signal CS3 to the switch S3 for turning it off, thereby connecting the capacitors C1 and C2 in parallel between the positive and negative sides of the battery 30. Meanwhile, the control unit 44 outputs a control signal CS1 to the switch S1 for turning it off, a control signal CS2 to the switch S2 for turning it off, and a control signal CS3 to the switch S3 for turning it on, thereby connecting the capacitors C1 and C2 in series between the positive and negative sides of the battery 30.

[0042] In the AC generating circuit 42-1, the capacitor C1 is an example of a "first capacitor" in the claims, and the capacitor C2 is an example of a "second capacitor" in the claims. In the AC generating circuit 42-1, the combination of the switches S1 and S2 is an example of a "parallel switch section" in the claims, and the switch S3 is an example of a "series switch section" in the claims. In the AC generating circuit 42-1, the switch S1 is an example of a "first switch" in the claims, the switch S2 is an example of a "second switch" in the claims, and the switch S3 is an example of a "third switch" in the claims. In the AC generating circuit 42-1, the inductor L3 is an example of an "inductor" in the claims. The control signal CS1 output by the control unit 44 to the switch S1 and the control signal CS2 output by the control unit 44 to the switch S2 are an example of a "first control signal" in the claims, and the control signal CS3 output by the control unit 44 to the switch S3 is an example of a "second control signal" in the claims. In the AC generating circuit 42-1, a state in which the capacitors C1 and C2 are connected in parallel between the positive and negative poles of the battery 30 is an example of a "first state" in the claims, and a state in which the capacitors C1 and C2 are connected in series between the positive and negative poles of the battery 30 is an example of a "second state" in the claims.

[0043] [Operation of the heating device] Here, let us consider the frequency of the AC current generated by the AC generating circuit 42-1. In order to efficiently heat the battery 30 by the temperature raising device 40, it is preferable that the AC current generated by the AC generating circuit 42-1 has a sine wave current waveform. From the viewpoint of control for causing the AC generating circuit 42-1 to generate an AC current, it is preferable that the duty ratio of the control signal output by the control unit 44 to the switches S1, S2, and S3 is 50 percent (%).

[0044] As described above, in the AC generating circuit 42-1, the capacitors C1 and C2 have the same capacitance. Therefore, in the AC generating circuit 42-1, when the capacitors C1 and C2 are connected in series to the battery 30, the total capacitance of the capacitors C1 and C2 is different from that of the capacitors C2 connected in parallel to the battery 30. More specifically, when the capacitors C1 and C2 are connected in series, the total capacitance of the AC generating circuit 42-1 is the sum of the reciprocals of the capacitances of the respective capacitors, that is, half the capacitance. On the other hand, when the capacitors C1 and C2 are connected in parallel, the total capacitance of the AC generating circuit 42-1 is the sum of the capacitances of the respective capacitors, that is, twice the capacitance. Therefore, in the AC generating circuit 42-1, the frequency of the AC current generated is different from that of the capacitors C1 and C2 connected in series to the battery 30.

[0045] Fig. 3 is an example of an equivalent circuit of the AC generating circuit 42-1 of the first embodiment. Fig. 3(a) shows an equivalent circuit when the capacitors C1 and C2 are connected in series to the battery 30, and Fig. 3(b) shows an equivalent circuit when the capacitors C1 and C2 are connected in parallel to the battery 30. In Fig. 3, the inductance component of the inductance La of the battery 30 is "Ls", and the resistance component of the resistor Ra is "Rs". The capacitance of the capacitors C1 and C2 is "Cx", and the inductance of the inductor L3 is "Ly".

[0046] 3(a), when the capacitors C1 and C2 are connected in series to the battery 30 in the AC generating circuit 42-1, the inductor L3 is short-circuited by the switch S3. In contrast, when the capacitors C1 and C2 are connected in parallel to the battery 30 in the AC generating circuit 42-1, the inductor L3 is disposed between the capacitors C1 and C2. In this way, in the AC generating circuit 42-1, by disposing the inductor L3 when the capacitors C1 and C2 are connected in parallel, the current waveform of the generated AC current can be made closer to a sine wave, and the control of each switch in the control unit 44 can be made easier (the duty ratio of the control signal output by the control unit 44 can be made closer to 50%).

[0047] <Comparative Example> [Configuration of AC generating circuit of comparative example] Here, in order to explain the effect of the inductor L3 included in the AC generating circuit 42-1, first, an AC generating circuit of a comparative example not including the inductor L3 (hereinafter, referred to as "AC generating circuit 42-C") will be explained. Fig. 4 is a diagram showing an example of the configuration of the AC generating circuit 42-C of the comparative example. The AC generating circuit 42-C has a configuration in which the inductor L3 is omitted from the AC generating circuit 42-1. The connections of the capacitor C1, the capacitor C2, the switch S1, the switch S2, and the switch S3 in the AC generating circuit 42-C are equivalent to those of the AC generating circuit 42-1.

[0048] Fig. 5 is an example of an equivalent circuit of an AC generating circuit 42-C of a comparative example. Fig. 5(a) shows an equivalent circuit in the case where the capacitors C1 and C2 are connected in series to the battery 30 in the AC generating circuit 42-C, and Fig. 5(b) shows an equivalent circuit in the case where the capacitors C1 and C2 are connected in parallel to the battery 30 in the AC generating circuit 42-C. In Fig. 5, as in the equivalent circuit of the AC generating circuit 42-1 shown in Fig. 3, the inductance component of the inductance La of the battery 30 is "Ls", the resistance component of the resistance Ra is "Rs", and the capacitance of the capacitors C1 and C2 is "Cx".

[0049] First, the frequency of the AC current generated by the AC generating circuit 42-C will be described with reference to Fig. 5. In the AC generating circuit 42-C, 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 formula (1).

[0050]

number

[0051] In addition, the resonance frequency ωs when the capacitors C1 and C2 are connected in series in the AC generating circuit 42-C can be calculated by the following formula (2).

[0052]

number

[0053] On the other hand, in the AC generating circuit 42-C, 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 formula (3).

[0054]

number

[0055] In addition, the resonance frequency ωp when the capacitors C1 and C2 are connected in parallel in the AC generating circuit 42-C can be calculated by the following equation (4).

[0056]

number

[0057] Here, when comparing the resonant frequency ωs when the capacitors C1 and C2 are connected in series in the AC generating circuit 42-C with the resonant frequency ωp when the capacitors C1 and C2 are connected in parallel, the ratio is expressed by the following equation (5).

[0058]

number

[0059] That is, in the AC generating circuit 42-C, the resonant frequency differs depending on the difference in the total capacitance between when the capacitors C1 and C2 are connected in series and when they are connected in parallel. More specifically, the resonant frequency when the capacitors C1 and C2 are connected in series is twice as high as the resonant frequency when the capacitors C1 and C2 are connected in parallel. Therefore, in the AC generating circuit 42-C, the current waveform of the AC current generated is not a sine wave, and the current waveform is asymmetric between the positive current value and the negative current value. Therefore, in the AC generating circuit 42-C, the AC current generated contains many harmonic components, and a lot of noise is emitted when the battery 30 is heated.

[0060] In order to generate an AC current of maximum amplitude in the AC generating circuit 42-C, the control unit 44 must output a control signal for switching the connection of the capacitors C1 and C2 to the battery 30 between a series connection or a parallel connection in a ratio of series connection = "1" and parallel connection = "2", that is, a duty ratio of 1:2. In other words, when the control unit 44 outputs a control signal with a duty ratio of 50% to each switch, it is not possible to generate an AC current of maximum amplitude.

[0061] [Operation of the temperature increasing device of the comparative example] Fig. 6 is a diagram showing an example of the operation waveforms (simulation waveforms) of the AC generating circuit 42-C of the comparative example. Fig. 6(a) shows an example of the control signals output by the control unit 44 to each switch, the AC current in the AC generating circuit 42-C, and the change in the output voltage, and Fig. 6(b) shows the AC current flowing in the AC generating circuit 42-C.

[0062] More specifically, FIG. 6(a) shows the control signals CS1, CS2, and CS3 that the control unit 44 outputs to each switch in order to generate an AC current in the AC generating circuit 42-C. In FIG. 6(a), the control signals CS1, CS2, and CS3 are set to a "High" level to make the corresponding switch conductive, and set to a "Low" level to make the corresponding switch non-conductive. The operation waveforms shown in FIG. 6(a) are an example of a case where the control unit 44 outputs a control signal with a duty ratio of 50% to each switch to generate a sine wave AC current in the AC generating circuit 42-C. As described above, the control unit 44 may provide a dead time for making all the switches non-conductive between a period in which the switches are made conductive and a period in which the switches are made non-conductive, but FIG. 6(a) shows a case where the control unit 44 controls each switch without providing a dead time.

[0063] 6(a) shows an example of the changes in the voltage V1-V0 between the two poles of the battery 30 (including the inductance La), the current I-C1 flowing through the capacitor C1, the current I-C2 flowing through the capacitor C2, and the current I-E1 flowing through the battery 30 (including the inductance La), which change as a result of the control of the control signals CS1, CS2, and CS3 by the control unit 44. FIG. 6(b) shows an example of the measurement position of the voltage V1-V0 and the directions in which the currents I-C1, I-C2, and I-E1 flow.

[0064] As shown in FIG. 6(a), in the series connection period PS when the control unit 44 sets the control signals CS1 and CS2 to the “Low” level and the control signal CS3 to the “High” level, the currents I-C1 and I-C2 flow from the positive region to the negative region, and the current I-E1 also flows from the positive region to the negative region. As a result, the voltage V1-V0 of the AC generating circuit 42-C drops from the positive peak voltage to the negative peak voltage, and then rises. On the other hand, in the parallel connection period PP when the control unit 44 sets the control signals CS1 and CS2 to the “High” level and the control signal CS3 to the “Low” level, the currents I-C1 and I-C2 flow from the negative region to the positive region, and the current I-E1 also flows from the negative region to the positive region. As a result, the voltage V1-V0 of the AC generating circuit 42-C rises toward the positive peak voltage, following the series connection period PS.

[0065] In this way, in the AC generating circuit 42-C, the control unit 44 outputs control signals to the respective switches to switch the connection of the capacitors C1 and C2 to the battery 30 between a series connection and a parallel connection, thereby generating an AC current. However, as can be seen from the waveforms of the current I-E1 and the voltage V1-V0 during the series connection period PS and the parallel connection period PP shown in FIG. 6(a), the amplitude of the current waveform of the AC current generated by the AC generating circuit 42-C is small. For this reason, as described above, the control unit 44 must output a control signal with a duty ratio of 1:2 in order to generate an AC current with the maximum amplitude in the AC generating circuit 42-C.

[0066] Here, in order to show the difference in the current waveform of the AC current depending on the duty ratio of the control signal, the operation will be described when the control unit 44 outputs a control signal with a duty ratio of 1:2 to each switch to generate an AC current of maximum amplitude in the AC generating circuit 42-C. FIG. 7 is a diagram showing another example of the operation waveform (simulation waveform) of the AC generating circuit 42-C of the comparative example. FIG. 7 also shows each control signal and the voltage and current that change according to the control signal, similar to the example of the operation waveform of the AC generating circuit 42-C in the control signal with a duty ratio of 50% shown in FIG. 6(a). That is, FIG. 7 shows an example of the control signal output by the control unit 44, the voltage V1-V0 between the two poles of the battery 30 (including the inductance La) that changes according to the control signal, and the current I-C1, the current I-C2, and the current I-E1 that flow through each component. The operation waveform shown in FIG. 7 is also an example of the case where the control unit 44 controls each switch without providing a dead time, similar to the example of the operation waveform of the AC generating circuit 42-C shown in FIG. 6. In the example shown in Figure 7, the measurement position of voltage V1-V0 and an example of the direction in which currents IC1, IC2, and I-E1 flow are similar to the example shown in Figure 6(b).

[0067] As shown in FIG. 7, in the series connection period PS, which is shortened by the control unit 44 outputting a control signal with a duty ratio of 1:2, the currents I-C1 and I-C2 flow into the positive region, and the current I-E1 also flows into the positive region. As a result, the voltage V1-V0 of the AC generating circuit 42-C drops from the positive peak voltage to the negative peak voltage. On the other hand, in the parallel connection period PP, which is lengthened by the control unit 44 outputting a control signal with a duty ratio of 1:2, the currents I-C1 and I-C2 flow into the negative region, and the current I-E1 also flows into the negative region. As a result, the voltage V1-V0 of the AC generating circuit 42-C rises from the negative peak voltage to the positive peak voltage.

[0068] In this way, in the AC generating circuit 42-C, the control unit 44 outputs control signals to each switch with a duty ratio of 1:2, so that an AC current with a larger amplitude (maximum amplitude) can be generated, as can be seen by comparing the waveforms of the current I-E1 and the voltage V1-V0 during the series connection period PS and the parallel connection period PP in Fig. 6(a) and Fig. 7. However, when the control unit 44 switches the connection of the capacitors C1 and C2 to the battery 30 to a series connection or a parallel connection with a duty ratio of 1:2, the current waveform of the AC current generated by the AC generating circuit 42-C is not a sine wave, and the amplitude also differs between the positive and negative regions of the AC current, as can be seen from the waveforms of the current I-E1 and the voltage V1-V0 during the series connection period PS and the parallel connection period PP shown in Fig. 7.

[0069] Returning to Fig. 3, the frequency of the AC current generated by the AC generating circuit 42-1 will be described. First, consider the resonant frequency when the capacitors C1 and C2 are connected in series as shown in Fig. 3(a). When the capacitors C1 and C2 are connected in series in the AC generating circuit 42-1, the inductor L3 is short-circuited by the switch S3 as described above, so Ly = 0. Therefore, in the AC generating circuit 42-1, the impedance Z when the capacitors C1 and C2 are connected in series can be calculated as in the above formula (1) as in the AC generating circuit 42-C, and the resonant frequency ωs can be calculated as in the above formula (2).

[0070] Next, consider the resonant frequency when the capacitors C1 and C2 are connected in parallel as shown in Fig. 3(b). When the capacitors C1 and C2 are connected in parallel in the AC generating circuit 42-1, the inductor L3 is disposed between the capacitors C1 and C2 as described above. Therefore, in the AC generating circuit 42-1, the impedance Z when the capacitors C1 and C2 are connected in parallel can be calculated by the following formula (6), unlike the AC generating circuit 42-C.

[0071]

number

[0072] In addition, the resonance frequency ωp when the capacitors C1 and C2 are connected in parallel in the AC generating circuit 42-1 can be calculated by the following equation (7).

[0073]

number

[0074] Therefore, in order to make the resonant frequency ωs when the capacitors C1 and C2 are connected in series in the AC generating circuit 42-1 equal to the resonant frequency ωp when the capacitors C1 and C2 are connected in parallel (equation (8) below), it is necessary to ensure that the following equation (9) holds.

[0075]

number

[0076]

number

[0077] For this reason, the inductance Ly of the inductor L3 in the AC generating circuit 42-1 should be set so that the following formula (10) holds.

[0078]

number

[0079] In other words, in the AC generating circuit 42-1, if the inductance Ly of the inductor L3 is set to one-third of the inductance component Ls of the inductance La of the battery 30, the resonant frequency ωs when the capacitors C1 and C2 are connected in series can be made equal to the resonant frequency ωp when the capacitors C1 and C2 are connected in parallel.

[0080] Fig. 8 is a diagram showing an example of the operation waveforms (simulation waveforms) of the AC generating circuit 42-1 of the first embodiment. Fig. 8 also shows each control signal and the voltage and current that change according to the control signal, as in the example of the operation waveforms of the AC generating circuit 42-C of the comparative example shown in Figs. 6 and 7. That is, Fig. 8 (a) shows an example of the control signal output by the control unit 44, the voltage V1-V0 between the two poles of the battery 30 (including the inductance La) that changes according to the control signal, and the currents I-C1, I-C2, and I-E1 that flow through the respective components, and Fig. 8 (b) shows an example of the measurement position of the voltage V1-V0 and the direction in which the currents I-C1, I-C2, and I-E1 flow.

[0081] The operation waveforms shown in Fig. 8(a) are an example of a case where the control unit 44 outputs control signals with a duty ratio of 50% to each switch to control the AC generating circuit 42-1 in order to generate a sine wave AC current. The operation waveforms shown in Fig. 8(a) are also an example of a case where the control unit 44 controls each switch without providing a dead time, similar to the example of the operation waveforms of the AC generating circuit 42-C of the comparative example shown in Fig. 6 and Fig. 7.

[0082] As shown in FIG. 8(a), in the AC generating circuit 42-1, during the series connection period PS when the control unit 44 sets the control signals CS1 and CS2 to the “Low” level and the control signal CS3 to the “High” level, the currents I-C1 and I-C2 flow mainly in the negative region, and the current I-E1 also flows mainly in the negative region. As a result, the voltage V1-V0 of the AC generating circuit 42-1 rises from the negative peak voltage to the positive peak voltage. On the other hand, in the AC generating circuit 42-1, during the parallel connection period PP when the control unit 44 sets the control signals CS1 and CS2 to the “High” level and the control signal CS3 to the “Low” level, the currents I-C1 and I-C2 flow mainly in the positive region, and the current I-E1 also flows mainly in the positive region. As a result, the voltage V1-V0 of the AC generating circuit 42-1 drops from the positive peak voltage to the negative peak voltage.

[0083] In this way, in the AC generating circuit 42-1, as in the AC generating circuit 42-C, the control unit 44 outputs a control signal to each switch to switch the connection of the capacitor C1 and the capacitor C2 to the battery 30 between a series connection and a parallel connection, thereby generating an AC current. Moreover, as can be seen from the waveforms of the current I-E1 and the voltage V1-V0 during the series connection period PS and the parallel connection period PP shown in Fig. 8(a), the current waveform of the AC current generated by the AC generating circuit 42-1 is closer to a sine wave than the current waveform of the AC current generated by the AC generating circuit 42-C shown in Fig. 6(a) and Fig. 7, and the difference in absolute value of the amplitude is smaller between the positive and negative regions of the AC current.

[0084] In this way, in the AC generating circuit 42-1, when the capacitors C1 and C2 are connected in parallel, the inductor L3 is arranged between the capacitors C1 and C2, so that the duty ratio of the control signal output by the control unit 44 can be set to 50%, and the current waveform of the generated AC current can be made closer to a sine wave. In other words, the AC generating circuit 42-1 can generate an AC current with a symmetrical current waveform when the current value is positive and when the current value is negative. This makes it easier to control the switches in the control unit 44, and the battery 30 can be heated more efficiently by the AC current with a current waveform close to a sine wave. In other words, the AC generating circuit 42-1 can generate an AC current with reduced harmonic components, and can reduce noise emitted when heating the battery 30.

[0085] For this reason, when the battery 30 mounted on the vehicle 1 is configured by combining a plurality of (e.g., two) batteries 30, the AC generating circuit 42-1 can be more easily applied as a configuration for raising the temperature by applying (passing) an AC current to each battery 30 and reducing the fluctuation in the overall voltage (so-called ripple in the voltage waveform) output by the set of the plurality of batteries 30. More specifically, when the battery 30 mounted on the vehicle 1 is configured by combining two batteries 30, the AC generating circuit 42-1 can be connected to each battery 30, and the control unit 44 can control the AC currents generated by each AC generating circuit 42-1 to be shifted in phase (shifted by 180°), thereby making it more easily applicable as a configuration for reducing the fluctuation in the overall voltage output by the set of two batteries 30.

[0086] [Another operation of the heating device] FIG. 9 is a diagram showing another example of the operation waveform (simulation waveform) of the AC generating circuit 42-1 of the first embodiment. FIG. 9 shows an example of a case where the battery 30 mounted on the vehicle 1 is configured by combining two batteries 30 (battery 30a and battery 30b). FIG. 9(a) shows the connection of the AC generating circuits 42-1 (AC generating circuits 42-1a and 42-1b) corresponding to each battery 30, and the AC current flowing through each AC generating circuit 42-1. FIG. 9(b) shows an example of the control signal output by the control unit 44 to each switch, the AC current in each AC generating circuit 42-1, and the change in the output voltage. In FIG. 9, "a" added to the end of each symbol indicates that it corresponds to the AC generating circuit 42-1a, and "b" indicates that it corresponds to the AC generating circuit 42-1b.

[0087] As shown in (a) of FIG. 9, in the case of a configuration in which two batteries 30 are combined, an AC generating circuit 42-1a is connected to one battery 30a, and an AC generating circuit 42-1b is connected to the other battery 30b. Then, the control unit 44 outputs a control signal to the switch provided in each AC generating circuit 42-1 so that the phases of the AC currents generated by each AC generating circuit 42-1 are shifted by 180°. (b) of FIG. 9 shows a case in which the control unit 44 outputs a control signal with a duty ratio of 50% to each AC generating circuit 42-1 in order to generate a sine wave AC current in each AC generating circuit 42-1. The control signal shown in (b) of FIG. 9 is also an example of a control signal when the control unit 44 controls each switch without providing a dead time.

[0088] 9(a) shows an example of the voltage measurement position and the current flow direction that change in each AC generating circuit 42-1 as a result of the control unit 44 controlling each switch by the control signal. More specifically, as an example of the voltage and current corresponding to the AC generating circuit 42-1a, the voltage V1-V0 between the two poles of the battery 30a (including the inductance Laa), the current I-C1a flowing through the capacitor C1a and the current I-C2a flowing through the capacitor C2a, and the current I-E1a flowing through the battery 30a (including the inductance Laa) are shown. Furthermore, as an example of the voltage and current corresponding to the AC generating circuit 42-1b, the voltage V2-V1 between the two poles of the battery 30b (including the inductance Lab), the current I-C1b flowing through the capacitor C1b and the current I-C2b flowing through the capacitor C2b, and the current I-E1b flowing through the battery 30b (including the inductance Lab) are shown. 9(a) shows the voltage V2-V0 across one end (V0) of the negative electrode side of the battery 30a in the AC generating circuit 42-1a and one end (V2) of the positive electrode side of the battery 30b in the AC generating circuit 42-1b as the total voltage of the combination of the batteries 30a and 30b. FIG. 9(b) shows an example of the changes in current and voltage in the AC generating circuit 42-1a and the AC generating circuit 42-1b.

[0089] As shown in FIG. 9B, the control unit 44 sets the control signals CS1a and CS2a of the AC generating circuit 42-1a to the “Low” level and sets the control signal CS3a to the “High” level during the period P1. As a result, in the AC generating circuit 42-1a, the capacitors C1a and C2a are connected in series via the inductor L3a, and as in the series connection period PS shown in FIG. 8B, the currents I-C1a and I-C2a flow mainly in the negative region, and the current I-E1a also flows mainly in the negative region. As a result, the voltage V1-V0 of the AC generating circuit 42-1a rises from a negative peak voltage to a positive peak voltage, as in the series connection period PS shown in FIG. 8B. On the other hand, during the period P1, the control unit 44 sets the control signals CS1b and CS2b of the AC generating circuit 42-1b to the “High” level and sets the control signal CS3b to the “Low” level. As a result, in the AC generating circuit 42-1b, the capacitors C1b and C2b are connected in parallel, and as in the parallel connection period PP shown in Fig. 8(b), the currents I-C1b and I-C2b flow mainly in the positive region, and the current I-E1b also flows mainly in the positive region. As a result, the voltage V2-V1 of the AC generating circuit 42-1b drops from a positive peak voltage to a negative peak voltage.

[0090] After that, as shown in FIG. 9(b), the control unit 44 sets the control signals CS1a and CS2a of the AC generating circuit 42-1a to the “High” level and sets the control signal CS3a to the “Low” level during the period P2. As a result, in the AC generating circuit 42-1a, the capacitors C1a and C2a are connected in parallel, and as in the parallel connection period PP shown in FIG. 8(b), the currents I-C1a and I-C2a flow mainly in the positive region, so that the current I-E1a also flows mainly in the positive region. As a result, the voltage V1-V0 of the AC generating circuit 42-1a drops from the positive peak voltage to the negative peak voltage. On the other hand, during the period P2, the control unit 44 sets the control signals CS1b and CS2b of the AC generating circuit 42-1b to the “Low” level and sets the control signal CS3b to the “High” level. As a result, in the AC generating circuit 42-1b, the capacitors C1b and C2b are connected in series via the inductor L3b, and as in the series connection period PS shown in Fig. 8(b), the currents I-C1b and I-C2b flow mainly in the negative region, and the current I-E1b also flows mainly in the negative region. As a result, the voltage V2-V1 of the AC generating circuit 42-1b rises from a negative peak voltage to a positive peak voltage, as in the series connection period PS shown in Fig. 8(b).

[0091] In this way, when the battery 30 mounted on the vehicle 1 is configured by combining two batteries 30 (here, battery 30a and battery 30b), the control unit 44 outputs control signals so that the AC generating circuits 42-1 corresponding to each battery 30 operate in opposite directions. This makes it possible to reduce the fluctuation in the overall voltage V2-V0 of the combined two batteries 30, as shown in Fig. 9(b). This is because the current waveform of the AC current generated by each AC generating circuit 42-1 is close to a sine wave that is symmetrical between positive and negative current values.

[0092] [Another operation of the temperature increasing device of the comparative example] 4 can also be applied to a configuration in which two batteries 30 are combined as the battery 30 mounted on the vehicle 1. However, since the current waveform of the AC current generated by the AC generating circuit 42-C is asymmetric between a positive current value and a negative current value, the effect of reducing the overall voltage fluctuation of the combination of the two batteries 30 is small.

[0093] Here, for comparison with the AC generating circuit 42-1, an example of the case where the AC generating circuit 42-C is applied to a configuration in which two batteries 30 are combined is shown. FIG. 10 is a diagram showing another example of the operation waveform of the AC generating circuit 42-C of the comparative example. FIG. 10 is an example of the case where the battery 30 mounted on the vehicle 1 is a configuration in which two batteries 30 (battery 30a and battery 30b) are combined, and the AC generating circuit 42-C is connected to each battery 30. The operation of the AC generating circuit 42-C and the control of the AC generating circuit 42-C in the control unit 44 in this case can be considered to be similar to the operation of the AC generating circuit 42-1 and the control of the AC generating circuit 42-1 in the control unit 44 shown in FIG. 9, with reference to the operation of the AC generating circuit 42-C shown in FIG. 6 and FIG. 7 and the control of the AC generating circuit 42-C in the control unit 44. Therefore, a detailed description of the operation of the AC generating circuit 42-C and the control of the AC generating circuit 42-C in the control unit 44 shown in FIG. 10 will be omitted.

[0094] Comparing the voltage waveform of the voltage V2-V0 shown in FIG. 9(b) with the voltage waveform of the voltage V2-V0 shown in FIG. 10(b), it can be seen that the effect of reducing the voltage fluctuation of the voltage V2-V0 is greater when the AC generating circuit 42-1 is applied to a configuration in which two batteries 30 are combined than when the AC generating circuit 42-C is applied to a configuration in which two batteries 30 are combined.

[0095] In this manner, in the temperature raising device 40 of the first embodiment, in the AC generating circuit 42-1, the inductor L3, whose inductance Ly is one third of the inductance component Ls of the inductance La of the battery 30, is connected in parallel between the first terminal and the second terminal of the switch S3. In the temperature raising device 40 of the first embodiment, when generating an AC current based on the power stored in the battery 30 by the resonance operation between the inductance La of the battery 30 and at least the capacitor C1, in the AC generating circuit 42-1, when the capacitors C1 and C2 are connected in parallel, the inductor L3 is arranged between the capacitors C1 and C2. As a result, in the temperature raising device 40 of the first embodiment, the current waveform of the generated AC current is made closer to a sine wave, the duty ratio of the control signal output by the control unit 44 is made closer to 50%, and the control of each switch by the control unit 44 can be facilitated. As a result, in the temperature raising device 40 of the first embodiment, it is possible to raise the temperature of the battery 30 more efficiently by using the AC current having a current waveform close to a sine wave generated by the AC generating circuit 42-1.

[0096] Furthermore, in the temperature raising device 40 of the first embodiment, for example, when the battery 30 mounted on the vehicle 1 is configured by combining two batteries 30, the control unit 44 controls the AC currents generated in each AC generating circuit 42-1 to be shifted in phase (shifted by 180°), thereby reducing fluctuations in the overall voltage output by the pair of batteries 30.

[0097] <Second embodiment> [Configuration of AC generating circuit in heating device] Fig. 11 is a diagram showing an example of the configuration of an AC generating circuit 42 (hereinafter referred to as "AC generating circuit 42-2") included in the temperature raising device 40 according to the second embodiment. Fig. 11 also shows a battery 30 related to the AC generating circuit 42-2. The AC generating circuit 42-2 includes, for example, a capacitor C1, a capacitor C2, a switch S1, a switch S2, a switch S31, a switch S32, an inductor L3, an inductor L10, and an inductor L20.

[0098] The AC generating circuit 42-2 has a configuration in which the switch S3 of the AC generating circuit 42-1 of the first embodiment is replaced by a configuration of two switches, the switch S31 and the switch S32, and an inductor L10 and an inductor L20 are added. The other components of the AC generating circuit 42-2, that is, the capacitor C1, the capacitor C2, the switch S1, the switch S2, and the inductor L3, are equivalent to those of the AC generating circuit 42-1 of the first embodiment. The inductors L10 and L20 are inductors having the same inductance. Similarly to the switch S3 of the AC generating circuit 42-1, the switches S31 and S32 are each 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) according to a control signal output by the control unit 44. In the following description, a control signal outputted from the control unit 44 for controlling the switch S31 to a conductive state or a non-conductive state is referred to as a "control signal CS31," and a control signal for controlling the switch S32 to a conductive state or a non-conductive state is referred to as a "control signal CS32." Each of the switches S31 and S32 may be a semiconductor switching element, such as an N-channel metal oxide semiconductor field effect transistor (MOSFET), similar to the switch S3 included in the AC generating circuit 42-1.

[0099] In the AC generating circuit 42-2, the first terminal of the capacitor C1 is connected to the positive electrode side of the battery 30, and the first terminal of the capacitor C2 is connected to the negative electrode side of the battery 30. Furthermore, in the AC generating circuit 42-2, the first terminal of the capacitor C1 is connected to the first terminal of the switch S2, and the second terminal of the switch S1 is connected to the first terminal of the capacitor C2. In the AC generating circuit 42-2, the second terminal of the switch S31, the second terminal of the inductor L3, and the second terminal of the inductor L20 are connected to the second terminal of the capacitor C1, and the first terminal of the switch S32, the first terminal of the inductor L3, and the first terminal of the inductor L10 are connected to the second terminal of the capacitor C2. Furthermore, in the AC generating circuit 42-2, the first terminal of the inductor L20 is connected between the first terminal of the switch S1 and the second terminal of the switch S32, and the second terminal of the inductor L10 is connected between the second terminal of the switch S2 and the first terminal of the switch S31.

[0100] With this configuration, in the AC generating circuit 42-2, the capacitors C1 and C2 are connected in parallel or in series between the positive and negative sides of the battery 30 in response to control from the control unit 44. More specifically, the control unit 44 outputs a control signal CS1 to the switch S1 to bring it into a conductive state, a control signal CS2 to the switch S2 to bring it into a conductive state, a control signal CS31 to the switch S31 to bring it into a non-conductive state, and a control signal CS32 to the switch S32 to bring it into a non-conductive state, thereby connecting the capacitors C1 and C2 in parallel between the positive and negative sides of the battery 30. On the other hand, the control unit 44 outputs a control signal CS1 to switch S1 to bring it into a non-conductive state, outputs a control signal CS2 to switch S2 to bring it into a non-conductive state, outputs a control signal CS31 to switch S31 to bring it into a conductive state, and outputs a control signal CS32 to switch S32 to bring it into a conductive state, thereby connecting the capacitors C1 and C2 in series between the positive and negative sides of the battery 30.

[0101] In the AC generating circuit 42-2, the capacitor C1 is an example of a "first capacitor" in the claims, and the capacitor C2 is an example of a "second capacitor" in the claims. In the AC generating circuit 42-2, the combination of the switches S1 and S2 is an example of a "parallel switch section" in the claims, and the combination of the switches S31 and S32 is an example of a "series switch section" in the claims. In the AC generating circuit 42-2, the switch S1 is an example of a "first switch" in the claims, the switch S2 is an example of a "second switch" in the claims, the switch S31 is an example of a "third switch" in the claims, and the switch S32 is an example of a "fourth switch" in the claims. In the AC generating circuit 42-2, the inductor L3 is an example of a "first inductor" in the claims, the inductor L10 is an example of a "second inductor" in the claims, and the inductor L20 is an example of a "third inductor" in the claims. The control signal CS1 output by the control unit 44 to the switch S1 and the control signal CS2 output by the control unit 44 to the switch S2 are an example of a "first control signal" in the claims, and the control signal CS31 output by the control unit 44 to the switch S31 and the control signal CS32 output by the control unit 44 to the switch S32 are an example of a "second control signal" in the claims. In the AC generating circuit 42-2, a state in which the capacitors C1 and C2 are connected in parallel between the positive and negative poles of the battery 30 is an example of a "first state" in the claims, and a state in which the capacitors C1 and C2 are connected in series between the positive and negative poles of the battery 30 is an example of a "second state" in the claims.

[0102] [Operation of the heating device] FIG. 12 is an example of an equivalent circuit of the AC generating circuit 42-2 of the second embodiment. FIG. 12(a) shows an equivalent circuit when the capacitors C1 and C2 are connected in series to the battery 30, and FIG. 12(b) shows an equivalent circuit when the capacitors C1 and C2 are connected in parallel to the battery 30. In FIG. 12 as well, the inductance component of the inductance La of the battery 30 is designated as "Ls" and the resistance component of the resistor Ra is designated as "Rs". The capacitances of the capacitors C1 and C2 are designated as "Cx", and the inductance of the inductor L3 is designated as "Ly". Furthermore, the inductances of the inductors L10 and L20 are designated as "Lx".

[0103] In the AC generating circuit 42-2, the capacitors C1 and C2 have the same capacitance, so that the total capacitance of the capacitors C1 and C2 when considered as one capacitor is different between the case where the capacitors C1 and C2 are connected in series to the battery 30 and the case where they are connected in parallel, as in the AC generating circuit 42-1. Therefore, in the AC generating circuit 42-2, the frequency of the AC current generated is different between the case where the capacitors C1 and C2 are connected in series to the battery 30 and the case where they are connected in parallel, as in the AC generating circuit 42-1. In the AC generating circuit 42-2, in order to efficiently heat the battery 30 by the temperature raising device 40, it is preferable that the current waveform of the AC current generated is a sine wave, and the duty ratio of the control signal output by the control unit 44 to the switch S1, the switch S2, the step S31, and the switch S32 is 50%. Here, the frequency of the AC current generated by the AC generating circuit 42-2 is considered.

[0104] First, the resonant frequency when the capacitors C1 and C2 are connected in series as shown in Fig. 12(a) will be described. When the capacitors C1 and C2 are connected in series in the AC generating circuit 42-2, a circuit consisting of the inductors L3, L10, and L20 is disposed between the capacitors C1 and C2. Therefore, the impedance Z when the capacitors C1 and C2 are connected in series in the AC generating circuit 42-2 can be calculated by the following formula (11).

[0105]

number

[0106] In the AC generating circuit 42-2, when the capacitors C1 and C2 are connected in series, the resonant frequency ωs is the frequency at which the impedance Z calculated by the above formula (11) is minimum and equal to the resistance component Rs. For this reason, the resonant frequency ωs should be such that the numerator of the first term on the right side of the above formula (11) is zero. In other words, the resonant frequency ωs should be such that the following formula (12) is satisfied.

[0107]

number

[0108] Then, from the above equation (12), the resonance frequency ωs can be obtained as shown in the following equation (13).

[0109]

number

[0110] Next, the resonant frequency when the capacitors C1 and C2 are connected in parallel as shown in (a) of Fig. 12 will be described. When the capacitors C1 and C2 are connected in parallel in the AC generating circuit 42-2, the inductor L10 is connected in series between the first end of the capacitor C1 and the second end of the capacitor C2, the inductor L20 is connected in series between the second end of the capacitor C1 and the first end of the capacitor C2, and the inductor L3 is connected between the inductor L10 and the inductor L20. Therefore, the impedance Z when the capacitors C1 and C2 are connected in parallel in the AC generating circuit 42-2 can be calculated by the following formula (14).

[0111]

number

[0112] Here, the resonant frequency ωp when the capacitors C1 and C2 are connected in parallel in the AC generating circuit 42-2 is the frequency at which the impedance Z calculated by the above formula (14) is minimum and equal to the resistance component Rs. Therefore, the resonant frequency ωp should be such that the numerator of the first term on the right side of the above formula (14) is zero. In other words, the resonant frequency ωp should be such that the following formula (15) is satisfied.

[0113]

number

[0114] Then, from the above equation (15), the resonance frequency ωp can be obtained as shown in the following equation (16).

[0115]

number

[0116] Here, when comparing the resonant frequency ωs and the resonant frequency ωp, the resonant frequency ωs can be expressed as in the following equation (17), and the resonant frequency ωp can be expressed as in the following equation (18).

[0117]

number

[0118]

number

[0119] Therefore, in order to make the resonant frequency ωs when the capacitors C1 and C2 are connected in series in the AC generating circuit 42-2 equal to the resonant frequency ωp when the capacitors C1 and C2 are connected in parallel, it is necessary to ensure that the following equation (19) holds.

[0120]

number

[0121] For this reason, the inductance Ly of the inductor L3 in the AC generating circuit 42-2 should be set so that the following formula (20) holds.

[0122]

number

[0123] This is the same as the AC generating circuit 42-1 of the first embodiment. That is, in the AC generating circuit 42-2 as well, if the inductance Ly of the inductor L3 is set to one third of the inductance component Ls of the inductance La of the battery 30, the resonance frequency ωs when the capacitors C1 and C2 are connected in series can be made equal to the resonance frequency ωp when the capacitors C1 and C2 are connected in parallel. As a result, in the AC generating circuit 42-2 as well, by connecting the capacitors C1 and C2 in series or in parallel, the current waveform of the generated AC current can be made closer to a sine wave, and the duty ratio of the control signal output by the control unit 44 can be made closer to 50%, making it easier to control each switch in the control unit 44.

[0124] Fig. 13 is a diagram showing an example of the operation waveforms (simulation waveforms) of the AC generating circuit 42-2 of the second embodiment. As with the example of the operation waveforms of the AC generating circuit 42-1 shown in Fig. 8, Fig. 13 also shows each control signal and the voltage and current that change according to the control signal. Fig. 13(a) shows an example of the control signal output by the control unit 44, the voltage V1-V0 between the two poles of the battery 30 (including the inductance La) that changes according to the control signal, and the currents I-C1, I-C2, and I-E1 that flow through the respective components, and Fig. 13(b) shows an example of the measurement position of the voltage V1-V0 and the direction in which the currents I-C1, I-C2, and I-E1 flow.

[0125] The operation waveforms shown in Fig. 13(a) are also an example of a case where the control unit 44 outputs control signals with a duty ratio of 50% to each switch to control the AC generating circuit 42-2 in order to generate a sine wave AC current. The operation waveforms shown in Fig. 13(a) are also an example of a case where the control unit 44 controls each switch without providing a dead time, similar to the example of the operation waveforms of the AC generating circuit 42-1 shown in Fig. 8.

[0126] As shown in FIG. 13(a), in the AC generating circuit 42-2, during the series connection period PS when the control unit 44 sets the control signals CS1 and CS2 to the “Low” level and the control signals CS31 and CS32 to the “High” level, the currents I-C1 and I-C2 flow mainly in the negative region, and the current I-E1 also flows mainly in the negative region. As a result, the voltage V1-V0 of the AC generating circuit 42-2 rises from the negative peak voltage to the positive peak voltage. On the other hand, in the AC generating circuit 42-2, during the parallel connection period PP when the control unit 44 sets the control signals CS1 and CS2 to the “High” level and the control signals CS31 and CS32 to the “Low” level, the currents I-C1 and I-C2 flow mainly in the positive region, and the current I-E1 also flows mainly in the positive region. As a result, the voltage V1-V0 of the AC generating circuit 42-2 drops from the positive peak voltage to the negative peak voltage.

[0127] In this way, in the AC generating circuit 42-2, as in the AC generating circuit 42-1, the control unit 44 outputs a control signal to each switch to switch the connection of the capacitor C1 and the capacitor C2 to the battery 30 between a series connection and a parallel connection, thereby generating an AC current. Moreover, as can be seen from the waveforms of the current I-E1 and the voltage V1-V0 during the series connection period PS and the parallel connection period PP shown in Fig. 13(a), the current waveform of the AC current generated by the AC generating circuit 42-2 is closer to a sine wave than the current waveform of the AC current generated by the AC generating circuit 42-1 shown in Fig. 8(a), and the difference in absolute value of the amplitude is also smaller between the positive and negative regions of the AC current.

[0128] In this manner, in the configuration of the AC generating circuit 42-2, similar to the AC generating circuit 42-1, the duty ratio of the control signal output by the control unit 44 can be set to 50%, and the current waveform of the generated AC current can be made closer to a sine wave. As a result, in the AC generating circuit 42-2, similar to the AC generating circuit 42-1, the control unit 44 can easily control each switch, and the battery 30 can be heated more efficiently by the AC current having a current waveform close to a sine wave. In addition, in the AC generating circuit 42-2, by generating an AC current that is closer to a sine wave, that is, with further reduced harmonic components, the noise emitted when the battery 30 is heated can be further reduced.

[0129] [Another operation of the heating device] Similarly to the AC generating circuit 42-1, the AC generating circuit 42-2 can be applied to a configuration in which the battery 30 mounted on the vehicle 1 is a combination of a plurality of batteries 30 (for example, two). FIG. 14 is a diagram showing another example of the operation waveforms (simulation waveforms) of the AC generating circuit 42-2 of the second embodiment. Similarly to another example of the operation waveforms of the AC generating circuit 42-1 shown in FIG. 9, FIG. 14 is an example of a case in which the battery 30 mounted on the vehicle 1 is a combination of two batteries 30 (battery 30a and battery 30b), and the AC generating circuit 42-2 is connected to each battery 30. FIG. 14(a) also shows the connection of the AC generating circuits 42-2 (AC generating circuit 42-2a and AC generating circuit 42-2b) corresponding to each battery 30, and the AC current flowing in each AC generating circuit 42-2. FIG. 14(b) also shows an example of a control signal output by the control unit 44 to each switch, and the AC current in each AC generating circuit 42-2 and the change in the output voltage.

[0130] As shown in (a) of FIG. 14, in the case of a configuration in which two batteries 30 are combined, an AC generating circuit 42-2a is connected to the battery 30a, and an AC generating circuit 42-2b is connected to the battery 30b. Then, the control unit 44 outputs a control signal to the switch provided in each AC generating circuit 42-2 so that the phases of the AC currents generated by each AC generating circuit 42-2 are shifted by 180°. (b) of FIG. 14 also shows a case in which the control unit 44 outputs a control signal with a duty ratio of 50% to each AC generating circuit 42-2 in order to generate a sine wave AC current in each AC generating circuit 42-2. The control signal shown in (b) of FIG. 14 is also an example of a control signal when the control unit 44 controls each switch without providing a dead time.

[0131] In this case, the operation of the AC generating circuit 42-2 and the control of the AC generating circuit 42-2 in the control unit 44 can be considered to be similar to the operation of the AC generating circuit 42-1 and the control of the AC generating circuit 42-1 in the control unit 44 shown in Fig. 9, with reference to the operation of the AC generating circuit 42-2 and the control of the AC generating circuit 42-2 in the control unit 44 shown in Fig. 13. Therefore, detailed description of the operation of the AC generating circuit 42-2 and the control of the AC generating circuit 42-2 in the control unit 44 shown in Fig. 14 will be omitted.

[0132] Comparing the voltage waveform of the voltage V2-V0 shown in FIG. 14(b) with the voltage waveform of the voltage V2-V0 shown in FIG. 9(b), it can be seen that the voltage fluctuation of the voltage V2-V0 is smaller when the AC generating circuit 42-2 is applied to a configuration in which two batteries 30 are combined than when the AC generating circuit 42-1 is applied to a configuration in which two batteries 30 are combined.

[0133] Thus, in the temperature raising device 40 of the second embodiment, the AC generating circuit 42-2 includes the inductor L3, which has an inductance Ly that is one-third of the inductance component Ls of the inductance La of the battery 30, and the inductors L10 and L20, which have the same inductance Lx. In the temperature raising device 40 of the second embodiment, when generating an AC current based on the power stored in the battery 30 by resonating with the inductance La of the battery 30 and at least the capacitor C1, in the AC generating circuit 42-2, different circuits including the inductor L3, the inductor L10, and the inductor L20 are arranged between the capacitor C1 and the capacitor C2 in the case where the capacitor C1 and the capacitor C2 are connected in series and in the case where the capacitor C1 and the capacitor C2 are connected in parallel. As a result, in the temperature raising device 40 of the second embodiment, the current waveform of the generated AC current is made closer to a sine wave, the duty ratio of the control signal output by the control unit 44 is made closer to 50%, and the control unit 44 can easily control each switch. As a result, in the temperature raising device 40 of the second embodiment, the temperature of the battery 30 can be raised more efficiently by the AC current having a current waveform closer to a sine wave, which is generated by the AC generating circuit 42-2.

[0134] Furthermore, in the second embodiment, like the heating device 40 of the first embodiment, when the battery 30 mounted on the vehicle 1 is configured by combining two batteries 30, the control unit 44 controls the AC currents generated in each AC generating circuit 42-2 to be shifted in phase (shifted by 180°), thereby reducing fluctuations in the overall voltage output by the pair of batteries 30.

[0135] Here, the difference in characteristics of the AC current generated by the AC generating circuit 42-C of the comparative example, the AC generating circuit 42-1 of the first embodiment, and the AC generating circuit 42-2 of the second embodiment will be described. FIG. 15 is a diagram comparing the characteristics of the AC current generated by the AC generating circuit 42 (the AC generating circuit 42-C, the AC generating circuit 42-1, and the AC generating circuit 42-2). FIG. 15(a) shows the characteristics of the ratio of harmonic components contained in the current waveform of the AC current generated by each AC generating circuit 42 when the fundamental wave component of the AC current generated by each AC generating circuit 42 is normalized as "1". FIG. 15(b) shows the characteristics of harmonic distortion in the current waveform of the AC current generated by each AC generating circuit 42. FIG. 15 compares the AC characteristics of the current I-E1 of the AC generating circuit 42-C shown in FIG. 7, the current I-E1 of the AC generating circuit 42-1 shown in FIG. 8, and the current I-E1 of the AC generating circuit 42-2 shown in FIG. 13.

[0136] As shown in FIG. 15(a), the ratios of the "second harmonic", "third harmonic", "fourth harmonic", and "fifth harmonic" when the fundamental wave component is "1" are the highest for the current I-E1 generated by the AC generating circuit 42-C, and low for the current I-E1 generated by the AC generating circuit 42-1 and the AC generating circuit 42-2. In particular, the third to fifth harmonics are low in the AC generating circuit 42-1 and the AC generating circuit 42-2. As shown in FIG. 15(b), the harmonic distortion in the current waveform of the current I-E1 generated by each AC generating circuit 42 is also the highest for the current I-E1 generated by the AC generating circuit 42-C, followed by the current I-E1 generated by the AC generating circuit 42-1, and then the current I-E1 generated by the AC generating circuit 42-2.

[0137] From these, it can be seen that the AC generating circuit 42-1 and the AC generating circuit 42-2 can generate a current I-E1 (AC current) with reduced harmonic components and harmonic distortion compared to the AC generating circuit 42-C. This is because the AC generating circuit 42-1 and the AC generating circuit 42-2 are provided with the inductor L3, so that the current waveform of the generated current I-E1 (AC current) is closer to a sine wave. Furthermore, it can be seen that the AC generating circuit 42-2 can generate a current I-E1 (AC current) with less harmonic distortion compared to the AC generating circuit 42-1. This is because the AC generating circuit 42-2 is further provided with the inductor L10 and the inductor L2, so that the current waveform of the generated current I-E1 (AC current) is closer to a sine wave than the current waveform of the current I-E1 (AC current) generated by the AC generating circuit 42-1.

[0138] As described above, according to the temperature raising device 40 of each embodiment, the AC generating circuit 42 is provided with the inductor L3 having an inductance Ly that is one-third of the inductance component Ls of the inductance La of the battery 30. In the temperature raising device 40 of each embodiment, the connection of the capacitors C1 and C2 of the AC generating circuit 42 to the battery 30 is switched between a series connection and a parallel connection, and an AC current based on the power stored in the battery 30 is generated by utilizing a resonance operation in which the magnetic energy stored in the inductance La of the battery 30 and the electrostatic energy stored at least in the capacitor C1 are alternately exchanged. At this time, in the temperature raising device 40 of each embodiment, when at least the capacitors C1 and C2 of the AC generating circuit 42 are connected in parallel to the battery 30, the inductor L3 is disposed between the capacitors C1 and C2. As a result, in the temperature raising device 40 of each embodiment, the current waveform of the AC current generated by the AC generating circuit 42 becomes a current waveform closer to a sine wave. As a result, in the heating device 40 of each embodiment, the battery 30 can be heated more efficiently by the AC current having a current waveform close to a sine wave generated by the AC generating circuit 42. As a result, in the vehicle 1 in which the heating device 40 of each embodiment is adopted, the battery 30 can be used in a state in which it has been heated to a suitable temperature, and deterioration in the charge / discharge performance of the battery 30 can be suppressed. Furthermore, in the vehicle 1 in which the heating device 40 of each embodiment is adopted, the AC current generated by the AC generating circuit 42 contains fewer harmonic components, so that noise emitted when the battery 30 is heated can be reduced.

[0139] Incidentally, in the temperature raising device 40 of each of the above-mentioned embodiments, the inductance Ly of the inductor L3 included in the AC generating circuit 42 (AC generating circuit 42-1 or 42-2) has been described as being one-third the value of the inductance component Ls of the inductance La of the battery 30. However, it is assumed that the inductance component Ls of the inductance La of the battery 30 varies in characteristics even between batteries 30 of the same type. Furthermore, it is assumed that the wiring portion connecting the AC generating circuit 42 and the battery 30 also contains an inductance component. For this reason, in the temperature raising device 40 of each of the embodiments, the inductance Ly of the inductor L3 included in the AC generating circuit 42 may be set to a value taking into consideration the variation in the inductance component Ls of the inductance La of the battery 30 and the inductance component included in the wiring portion connecting the AC generating circuit 42 and the battery 30. That is, in the temperature raising device 40 of each embodiment, the inductance Ly of the inductor L3 may be set to a value having a certain range with respect to one-third of the inductance component Ls of the inductance La of the battery 30, as long as the current waveform of the AC current generated by the AC generating circuit 42 is within a range in which it can be considered as a sine wave (a range in which a substantial effect can be obtained). In other words, in the temperature raising device 40 of each embodiment, the inductance Ly of the inductor L3 provided in the AC generating circuit 42 may be set to a value within a range that can be said to be one-third of the substantial inductance component Ls of the inductance La of the battery 30, that is, a range of approximately one-third. For example, in the temperature raising device 40 of each embodiment, the inductance Ly of the inductor L3 provided in the AC generating circuit 42 may be set to a value within a range with a range from one-quarter to two-fifths of the inductance component Ls of the inductance La of the battery 30.

[0140] In the temperature raising device 40 of each embodiment described above, the control unit 44 may output a duty ratio of 50% to each switch. However, as described above, the control unit 44 may control the switches by providing a dead time for making all the switches non-conductive between a period in which the switches are in a conductive state and a period in which the switches are in a non-conductive state. For example, in the temperature raising device 40 of each embodiment, the control unit 44 may provide a dead time by setting the duty ratio of the control signal 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 to each switch to switch the connection of the capacitor C1 and the capacitor C2 to the battery 30 from a parallel connection to a series connection, or vice versa.

[0141] According to the temperature raising device 40 of each of the embodiments 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 C1 having a first end connected to the positive electrode side of the battery 30, a capacitor C2 having a first end connected to the negative electrode side of the battery 30, a parallel switch unit that connects the second end of the capacitor C1 to the first end of the capacitor C2 and connects the first end of the capacitor C1 to the second end of the capacitor C2 in response to a first control signal (e.g., control signal CS1 and control signal CS2), thereby connecting the capacitors C1 and C2 in parallel to the battery 30, a series switch unit that connects the second end of the capacitor C1 to the second end of the capacitor C2 in response to a second control signal (e.g., control signal CS3), thereby connecting the capacitors C1 and C2 in series to the battery 30, and an inductor L3 connected between both terminals of the series switch unit. This makes it possible to more efficiently raise the temperature of the battery 30 for traveling mounted on the vehicle 1. As a result, in a vehicle 1 employing the heating device 40 of each 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. This allows the vehicle 1 equipped with the heating device 40 of each embodiment to improve the marketability of the vehicle 1, such as by improving durability. For these reasons, the vehicle 1 equipped with the heating device 40 of each embodiment is expected to contribute to improving energy efficiency and reducing adverse effects on the global environment.

[0142] In each of the above-described embodiments, a configuration has been described in which the control device 100 controls the start or stop of the temperature raising device 40, and the control unit 44 controls each switch included 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, included 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 in the temperature raising device 40.

[0143] 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]

[0144] 1. Vehicle 10. Engine 12. Motor 14...Reducer 16... Drive wheel 20···PDU 30, 30a, 30b... Battery 32 Battery sensor 40. Heating device 42,42-1,42-1a,42-1b,42-2,42-2a,42-2b...AC generation circuit 44 Control section 70 Driving controls 80 Vehicle sensor 100... Control device C1, C1a, C1b... Capacitors C2, C2a, C2b... Capacitors S1, S1a, S1b, S2, S2a, S2b... Switches S3, S3a, S3b... Switch S31, S31a, S31b, S32, S32a, S32b... Switch L3, L3a, L3b...inductor L10, L10a, L10b, L20, L20a, L20b...inductor La,Laa,Lab...Inductance

Claims

1. 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 a positive electrode side of the power storage unit; a second capacitor having a first 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 first end of the second capacitor and connects the first end of the first capacitor to the second end of the second capacitor in response to a first control signal, 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 second end of the second capacitor in response to a second control signal, thereby connecting the first capacitor and the second capacitor in series to the power storage unit; an inductor connected between both terminals of the series switch section; An alternating current generating circuit comprising:

2. 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 first 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 second end of the second capacitor; having the series switch unit includes a third switch having a first terminal connected to the second end of the second capacitor and a second terminal connected to the second end of the first capacitor, the inductor is connected in parallel between the first terminal of the third switch and the second terminal of the third switch.

2. The alternating current generating circuit according to claim 1.

3. The inductance of the inductor is approximately one-third of the inductance component.

3. The AC generating circuit according to claim 2.

4. The parallel switch unit includes: a first switch having a first terminal connected to the second end side of the first capacitor and a second terminal connected to the first 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 second end of the second capacitor; having The series switch unit includes: a third switch having a first terminal connected to the second terminal of the second switch and a second terminal connected to the second end of the first capacitor; a fourth switch having a first terminal connected to the second end of the second capacitor and a second terminal connected to the first terminal of the first switch; having The inductor is a first inductor having a first end connected to the first terminal of the fourth switch and a second end connected to the second terminal of the third switch; a second inductor having a first end connected to the first end of the first inductor and a second end connected between the second terminal of the second switch and the first terminal of the third switch; a third inductor having a first end connected between the first terminal of the first switch and the second terminal of the fourth switch and a second end connected to the second end of the first inductor; 2. The AC generating circuit of claim 1 , comprising:

5. The inductance of the first inductor is approximately one-third of the inductance component.

5. The AC generating circuit according to claim 4.

6. The inductance of the second inductor is equal to the inductance of the third inductor.

6. An AC generating circuit as claimed in claim 5.

7. The inductance component includes an inductance component in a wiring portion between the power storage unit and the AC generating circuit.

7. An AC generating circuit according to claim 1, wherein the AC generating circuit is a first AC power supply.

8. An AC generating circuit according to any one of claims 1 to 7; outputting, as the first control signal, a signal having a predetermined duty ratio for putting the parallel switch unit into a conductive state or a non-conductive state; outputting, as the second control signal, a signal having the predetermined duty ratio that puts the series switch unit into a conductive state or a non-conductive state; a control unit that alternately switches between a first state in which the parallel switch unit is in a conductive state and the series switch unit is in a non-conductive state and a second state in which the parallel switch unit is in a non-conductive state and the series switch unit is in a conductive state, according to the first control signal and the second control signal; A heating device comprising:

9. The predetermined duty ratio is approximately 50 percent. The temperature raising device according to claim 8.

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