AC generating circuit and heating device

Abstract

The present invention provides an AC generating circuit and a heating device. The AC generating circuit includes: a first capacitor, the first terminal of which is connected to the positive terminal of a storage medium having an inductive component; a second capacitor, the first terminal of which is connected to the negative terminal of the storage medium; a parallel switch unit that, according to a first control signal, connects the second terminal of the first capacitor to the first terminal of the second capacitor, and connects the first terminal of the first capacitor to the second terminal of the second capacitor, thereby connecting the first capacitor and the second capacitor in parallel to the storage medium; a series switch unit that, according to a second control signal, connects the second terminal of the first capacitor to the second terminal of the second capacitor, thereby connecting the first capacitor and the second capacitor in series to the storage medium; and an inductor connected between the two terminals of the series switch unit.

Description

Technical Field

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

[0002] Used to mitigate adverse impacts on the Earth's environment (e.g., NO) x SO x Countermeasures to reduce CO2 emissions are progressing rapidly. Therefore, in recent years, from the perspective of improving the global environment, there has been increased attention on electric vehicles, such as hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs), which operate by at least an electric motor, and which utilize electricity supplied by a battery (secondary battery) to drive the electric motor. Furthermore, the use of lithium-ion secondary batteries for vehicle applications has been studied. In these electric vehicles, maximizing the performance of the secondary battery is crucial. It is known that if the temperature of a secondary battery drops below a suitable range during use, its charge and discharge performance decreases. However, by raising the secondary battery to a suitable temperature during use, the decline in charge and discharge performance can be suppressed.

[0003] In this regard, for example, Japanese Patent No. 5293820 discloses a technology related to a heating device for heating a secondary battery. In the heating device disclosed in Japanese Patent No. 5293820, based on the frequency characteristics of the impedance of the secondary battery, a ripple current of a predetermined frequency in a frequency region where the absolute value of the impedance relatively decreases is actively generated in the secondary battery, thereby heating the secondary battery. Summary of the Invention

[0004] However, in existing technologies, there are situations where it is not possible to efficiently heat up secondary batteries.

[0005] This invention is based on the understanding of the above-mentioned problems, and one of its objectives is to provide an AC generating circuit and a heating device that can improve energy efficiency by making the secondary battery heat up more efficiently.

[0006] Solution for solving the problem

[0007] The AC generating circuit and heating device of the present invention adopt the following structure.

[0008] (1): An AC generating circuit of one aspect of the present invention heats up the energy storage body by generating an AC current based on the power stored in the energy storage body, the energy storage body having an inductive component, wherein the AC generating circuit comprises: a first capacitor, the first terminal of which is connected to the positive side of the energy storage body; a second capacitor, the first terminal of which is connected to the negative side of the energy storage body; a parallel switch unit, which connects the second terminal of the first capacitor to the first terminal of the second capacitor and the first terminal of the second capacitor to the second terminal of the second capacitor according to a first control signal, thereby connecting the first capacitor and the second capacitor in parallel to the energy storage body; a series switch unit, which connects the second terminal of the first capacitor to the second terminal of the second capacitor according to a second control signal, thereby connecting the first capacitor and the second capacitor in series to the energy storage body; and an inductor connected between the two terminals of the series switch unit.

[0009] (2): Based on the above (1) scheme, the parallel switch section has: a first switch, the first terminal of which is connected to the second terminal of the first capacitor, and the second terminal of which is connected to the first terminal of the second capacitor; and a second switch, the first terminal of which is connected to the first terminal of the first capacitor, and the second terminal of which is connected to the second terminal of the second capacitor; the series switch section has a third switch, the first terminal of which is connected to the second terminal of the second capacitor, and the second terminal of which is connected to the second terminal 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.

[0010] (3): Based on the above (2) scheme, the inductance of the inductor is approximately one-third of the inductance component.

[0011] (4): Based on the above (1) scheme, the parallel switch section includes: a first switch, the first terminal of which is connected to the second end of the first capacitor, and the second terminal of which is connected to the first end of the second capacitor; and a second switch, the first terminal of which is connected to the first end of the first capacitor, and the second terminal of which is connected to the second end of the second capacitor; the series switch section includes: a third switch, the first terminal of which is connected to the second terminal of the second switch, and the second terminal of which is connected to the second end of the first capacitor; and a fourth switch, the first terminal of which is connected to the second end of the second capacitor. The fourth switch is connected to the first terminal of the first switch. The inductor comprises: a first inductor, the first end of which is connected to the first terminal of the fourth switch, and the second end of which is connected to the second terminal of the third switch; a second inductor, the first end of which is connected to the first end of the first inductor, and the second end of which is connected between the second terminal of the second switch and the first terminal of the third switch; and a third inductor, the first end of which is connected between the first terminal of the first switch and the second terminal of the fourth switch, and the second end of which is connected to the second end of the first inductor.

[0012] (5): Based on the above (4) scheme, the inductance of the first inductor is approximately one-third of the inductance component.

[0013] (6): Based on the above scheme (5), the inductance of the second inductor is equal to the inductance of the third inductor.

[0014] (7): Based on any of the above schemes (1) to (6), the inductance component includes the inductance component of the wiring portion between the energy storage body and the AC generation circuit.

[0015] (8): A heating device according to one aspect of the present invention includes: an AC generating circuit of any one of the aspects (1) to (7) above; and a control unit that outputs a signal with a predetermined duty cycle that makes the parallel switch part in a conducting state or a non-conducting state as a first control signal, and outputs a signal with the predetermined duty cycle that makes the series switch part in a conducting state or a non-conducting state as a second control signal, and alternately switches between a first state and a second state by means of the first control signal and the second control signal, wherein the first state is a state in which the parallel switch part is in a conducting state and the series switch part is in a non-conducting state, and the second state is a state in which the parallel switch part is in a non-conducting state and the series switch part is in a conducting state.

[0016] (9): Based on the above scheme (8), the specified duty cycle is approximately 50%.

[0017] Invention Effects

[0018] According to the schemes (1) to (9) above, energy efficiency can be improved by making the secondary battery heat up more efficiently. Attached Figure Description

[0019] Figure 1 This is a diagram illustrating an example of the structure of a vehicle employing the heating device of the embodiment.

[0020] Figure 2 This is a diagram showing an example of the structure of the AC generation circuit included in the heating device of the first embodiment.

[0021] Figure 3 This is an example of an equivalent circuit of the AC generation circuit in the first embodiment.

[0022] Figure 4 This is a diagram illustrating an example of the structure of the AC generating circuit of the comparative example.

[0023] Figure 5 This is an example of the equivalent circuit of the AC generating circuit in the comparative example.

[0024] Figure 6 This is a diagram illustrating an example of the operating waveform of the AC generating circuit of the comparative example.

[0025] Figure 7 This is another example of the operating waveform of the AC generating circuit of the comparative example.

[0026] Figure 8 This is a diagram showing an example of the operating waveform of the AC generation circuit of the first embodiment.

[0027] Figure 9This is a diagram showing another example of the operating waveform of the AC generation circuit of the first embodiment.

[0028] Figure 10 This is another example of the operating waveform of the AC generating circuit of the comparative example.

[0029] Figure 11 This is a diagram showing an example of the structure of the AC generation circuit included in the heating device of the second embodiment.

[0030] Figure 12 This is an example of an equivalent circuit of the AC generation circuit in the second embodiment.

[0031] Figure 13 This is a diagram illustrating an example of the operating waveform of the AC generation circuit according to the second embodiment.

[0032] Figure 14 This is a diagram showing another example of the operating waveform of the AC generation circuit of the second embodiment.

[0033] Figure 15 This is a graph comparing the characteristics of the alternating current generated by an alternating current generating circuit. Detailed Implementation

[0034] Hereinafter, embodiments of the AC generating circuit and heating device of the present invention will be described with reference to the accompanying drawings.

[0035] [Vehicle Structure]

[0036] Figure 1 This diagram illustrates an example of the structure of a vehicle employing the heating device of the embodiment. Vehicle 1 is a hybrid electric vehicle (HEV) (hereinafter simply referred to as "vehicle") that combines the drive of an electric motor (electric motor) powered by electricity supplied from a driving battery (secondary battery) with the drive of an internal combustion engine powered by fuel, such as a diesel engine or a gasoline engine. Vehicles applying this invention can be, for example, not only four-wheeled vehicles, but also straddle-type two-wheeled vehicles, three-wheeled vehicles (including vehicles with two front wheels and one rear wheel in addition to the front and two rear wheels), and auxiliary bicycles, etc., all vehicles driven by an electric motor, wherein the electric motor is driven by electricity supplied from the driving battery. Vehicle 1 can also be, for example, an electric vehicle (EV) driven solely by an electric motor (electric motor).

[0037] Vehicle 1 includes, for example, an engine 10, a motor 12, a reducer 14, drive wheels 16, a PDU (Power Drive Unit) 20, a battery 30, a battery sensor 32, a heating device 40, driving controls 70, vehicle sensors 80, and a control device 100.

[0038] Engine 10 is an internal combustion engine that burns fuel such as light oil or gasoline stored in a fuel tank (not shown) in vehicle 1 to generate power through rotation. Engine 10 is, for example, a reciprocating engine equipped with cylinders and pistons, intake valves, exhaust valves, a fuel injection device, spark plugs, connecting rods, a crankshaft, etc. Engine 10 can also be a rotary engine. The rotational power of engine 10 is transmitted to reduction gear 14.

[0039] Motor 12 is a rotary electric motor used for driving vehicle 1. Motor 12 is, for example, a three-phase AC motor. The rotating part (rotor) of motor 12 is connected to reducer 14. Motor 12 is driven (rotated) using power supplied from battery 30 via PDU 20. The rotational power of motor 12 is transmitted to reducer 14. Motor 12 can also operate as a regenerative brake that uses the kinetic energy of vehicle 1 during deceleration to generate electricity. Motor 12 may also include a generator. The generator uses, for example, the rotational power output from engine 10 to generate electricity.

[0040] The reducer 14 is, for example, a differential gear. The reducer 14 transmits the driving force, i.e., the rotational power of the engine 10 and motor 12, to the axle connected to the drive wheel 16. The reducer 14 may also include, for example, a transmission mechanism that combines multiple gears and shafts to change the rotational speed of the engine 10 and motor 12 according to a gear ratio before transmitting the speed to the axle; this is known as a drive mechanism. The reducer 14 may also include, for example, a clutch mechanism that directly connects or disconnects the rotational power of the engine 10 and motor 12 from the axle.

[0041] PDU 20 is, for example, an inverter, a DC-DC converter, or an AC-DC converter. PDU 20 converts the DC power supplied from battery 30 into three-phase AC power for driving motor 12 and outputs it to motor 12. PDU 20 may also include a VCU (Voltage Control Unit) that boosts the DC power supplied from battery 30. PDU 20 converts the three-phase AC power generated by motor 12, which operates as a regenerative brake, into DC power and outputs it to battery 30. PDU 20 may also boost or buck the voltage before outputting it in conjunction with the power output destination. Figure 1In this paper, the structural elements of PDU20 are shown as a unified structure, but this is only one example. The various structural elements of PDU20 can also be distributed in the vehicle 1.

[0042] Battery 30 is the battery used for driving vehicle 1. Battery 30 is a rechargeable and dischargeable secondary battery, such as a lithium-ion battery, as its energy storage unit. Battery 30 can be a box-type battery pack or a fixed structure that is not easily installed or removed from vehicle 1. The secondary battery included in battery 30 is, for example, a lithium-ion battery. As a secondary battery included in battery 30, in addition to lead-acid batteries, nickel-metal hydride batteries, sodium-ion batteries, etc., capacitors such as double-layer capacitors, or composite batteries obtained by combining secondary batteries and capacitors, etc., are also considered, but the structure of the secondary battery can be any form. Battery 30 stores electricity (charges) introduced from an external charger (not shown) of vehicle 1 and releases the stored electricity to drive vehicle 1. Battery 30 stores electricity (charges) supplied via PDU 20 and generated by motor 12, which operates as a regenerative brake, and releases the stored electricity to drive vehicle 1 (e.g., accelerate). The storage battery 30 has at least an inductive component.

[0043] The storage battery 30 is an example of the "energy storage body" in the claims, and the inductive component of the storage battery 30 connected to the energy storage unit is an example of the "inductive component" in the claims.

[0044] A battery sensor 32 is connected to the battery 30. The battery sensor 32 detects physical quantities such as voltage, current, and temperature of the battery 30. The battery sensor 32 may include, for example, a voltage sensor, a current sensor, and a temperature sensor. The battery sensor 32 detects the voltage of the battery 30 through the voltage sensor, the current of the battery 30 through the current sensor, and the temperature of the battery 30 through the temperature sensor. The battery sensor 32 outputs the detected voltage, current, and temperature information of the battery 30 (hereinafter referred to as "battery information") to the control device 100.

[0045] The heating device 40 raises the temperature of the battery 30 according to the control from the control device 100. The heating device 40 includes, for example, an AC generation circuit 42 and a control unit 44.

[0046] The AC generating circuit 42 includes, for example, a first capacitor connected to the positive terminal of the battery 30, a second capacitor connected to the negative terminal of the battery 30, a parallel switch connecting the first and second capacitors in parallel to the battery 30, a series switch connecting the first and second capacitors in series to the battery 30, and an inductor connected between the two terminals of the series switch. The AC generating circuit 42 generates alternating current through the resonant operation of the inductive component of the battery 30 and at least the first capacitor. More specifically, the AC generating circuit 42 generates an alternating current based on the power stored in the battery 30 through a resonant operation that alternately exchanges the magnetic energy stored in the inductive component of the battery 30 and the electrostatic energy stored in at least the first capacitor. The AC generating circuit 42 raises the temperature of the battery 30 by applying the generated alternating current to (flowing towards) the battery 30.

[0047] The control unit 44 switches the connection of the first capacitor and the second capacitor to the battery 30 to either a parallel connection or a series connection by turning the parallel switch and the series switch of the AC generating circuit 42 into a conducting state or a non-conducting state, respectively. More specifically, the control unit 44 alternately switches between two states: one state is a state in which the first capacitor and the second capacitor are connected in parallel to the battery 30 by turning the parallel switch on and the series switch off; the other state is a state in which the first capacitor and the second capacitor are connected in series to the battery 30 by turning the parallel switch off and the series switch on. At this time, the control unit 44 may also set a period during which both the parallel switch and the series switch are turned off, i.e., a so-called dead time, thereby switching the connection of the first capacitor and the second capacitor to the battery 30 from a parallel connection to a series connection or from a series connection to a parallel connection.

[0048] The state in which the first capacitor and the second capacitor are connected in parallel to the storage battery 30 is an example of the "first state" in the claims, and the state in which the first capacitor and the second capacitor are connected in series to the storage battery 30 is an example of the "second state" in the claims. The heating device 40 and its structural elements will then be described in detail.

[0049] The driving control unit 70 includes, for example, an accelerator pedal, a brake pedal, a gearshift lever, a steering wheel, a custom steering wheel, a joystick, and other control components. A sensor is installed in the driving control unit 70 to detect whether the user (driver) of the vehicle 1 is operating any of the control components or to detect the amount of operation. The driving control unit 70 outputs the sensor detection results to the control device 100.

[0050] Vehicle sensor 80 detects the driving status of vehicle 1. Vehicle sensor 80 includes, for example, a speed sensor to detect the speed of vehicle 1 and an acceleration sensor to detect the acceleration of vehicle 1. Vehicle sensor 80 outputs the detection results detected by each sensor to control device 100.

[0051] The control device 100 controls the operation and movement of the engine 10 and the motor 12 based on the detection results output by the various sensors provided by the driving control unit 70, that is, the operation of the various control units 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 composed of 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 also be replaced by control devices such as an engine ECU (Electronic Control Unit), a motor ECU, a battery ECU, a PDU-ECU, and a VCU-ECU.

[0052] When the vehicle 1 is in motion, the control device 100 controls the amount of AC power supplied from the battery 30 to the motor 12 and the frequency (i.e., voltage waveform) of the supplied AC power. At this time, the control device 100 controls the activation of the heating device 40 based on the battery temperature information included in the battery information output by the battery sensor 32. That is, in order to suppress the degradation of the charging and discharging performance of the battery 30, the control device 100 controls the activation or deactivation of the heating device 40, causing the temperature of the battery 30 to rise (heat) to a suitable temperature for use.

[0053] The control device 100 operates, for example, by executing a program (software) using a hardware processor such as a CPU (Central Processing Unit). The control device 100 can be implemented using hardware (including a circuitry) such as an LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), or GPU (Graphics Processing Unit), or through a combination of software and hardware. The control device 100 can also be implemented using a dedicated LSI. The program can be pre-stored in a storage device (a storage device with a non-transitory storage medium) such as an HDD (Hard Disk Drive) or flash memory in the vehicle 1, or it can be stored in a removable storage medium (a non-transitory storage medium) such as a DVD or CD-ROM and installed in the HDD or flash memory of the vehicle 1 by assembling the storage medium into a drive unit in the vehicle 1.

[0054] <First Implementation>

[0055] [The structure of the AC generation circuit in the heating device]

[0056] Figure 2 This is a diagram illustrating an example of the structure of the AC generation circuit 42 (hereinafter referred to as "AC generation circuit 42-1") included in the heating device 40 of the first embodiment. Figure 2 Also shown is a battery 30 associated with the AC generating circuit 42-1. The battery 30 has, for example, a resistor Ra and an inductor La connected in series on the positive terminal side of the energy storage section Ba. The inductor La connected to the energy storage section Ba in the battery 30 is an example of the "inductive component" in the claims.

[0057] The AC generating circuit 42-1 includes, for example, capacitor C1, capacitor C2, switch S1, switch S2, switch S3, and inductor L3. Capacitor C1 and capacitor C2 are capacitors with equal electrostatic capacitance. Switches S1, S2, and S3 are controlled, according to the control signal output from the control unit 44, to either be in a conducting state (closed state) or a non-conducting state (open state) that connects the two terminals. In the following description, the control signal output from the control unit 44 that controls switch S1 to be in a conducting or non-conducting state is called "control signal CS1", the control signal that controls switch S2 to be in a conducting or non-conducting state is called "control signal CS2", and the control signal that controls switch S3 to be in a conducting or non-conducting state is called "control signal CS3".

[0058] Switches S1, S2, and S3 can each be, for example, an N-channel metal oxide semiconductor field-effect transistor (MOSFET), a semiconductor switching element that can be controlled to be in any on or off state. In this case, it can also be a structure that includes a diode connected in parallel for return current. When switches S1, S2, and S3 are each composed of semiconductor switching elements, the control unit 44 outputs a gate signal that makes the semiconductor switching elements in an on or off state, serving as a control signal to control switches S1, S2, and S3 to be in a conducting or non-conducting state, respectively.

[0059] In AC generating circuit 42-1, the first terminal of capacitor C1 is connected to the positive terminal of battery 30, and the first terminal of capacitor C2 is connected to the negative terminal of battery 30. Furthermore, in AC generating circuit 42-1, the first terminal of switch S2 is connected to the first terminal of capacitor C1, and the second terminal of switch S1 is connected to the first terminal of capacitor C2. Also, in AC generating circuit 42-1, the first terminal of switch S1 and the second terminal of switch S3 are connected to the second terminal of capacitor C1, and the second terminal of switch S2 and the first terminal of switch S3 are connected to the second terminal of capacitor C2. Additionally, in AC generating circuit 42-1, an inductor L3 is connected in parallel between the first and second terminals of switch S3.

[0060] With this structure, in the AC generating circuit 42-1, according to the control from the control unit 44, capacitor C1 and capacitor C2 are connected in parallel or in series between the positive and negative terminals of the battery 30. More specifically, the control unit 44 outputs a control signal CS1 to switch S1 to make it conduct, a control signal CS2 to switch S2 to make it conduct, and a control signal CS3 to switch S3 to make it deconduct, thereby connecting capacitor C1 and capacitor C2 in parallel between the positive and negative terminals of the battery 30. On the other hand, the control unit 44 outputs a control signal CS1 to switch S1 to make it deconduct, a control signal CS2 to switch S2 to make it deconduct, and a control signal CS3 to switch S3 to make it conduct, thereby connecting capacitor C1 and capacitor C2 in series between the positive and negative terminals of the battery 30.

[0061] In AC generating circuit 42-1, capacitor C1 is an example of the "first capacitor" in the claims, and capacitor C2 is an example of the "second capacitor" in the claims. In AC generating circuit 42-1, the structure combining switches S1 and S2 is an example of the "parallel switch section" in the claims, and switch S3 is an example of the "series switch section" in the claims. In AC generating circuit 42-1, switch S1 is an example of the "first switch" in the claims, switch S2 is an example of the "second switch" in the claims, and switch S3 is an example of the "third switch" in the claims. In AC generating circuit 42-1, inductor L3 is an example of the "inductor" in the claims. The control signal CS1 output by control unit 44 to switch S1 and the control signal CS2 output by control unit 44 to switch S2 are examples of the "first control signal" in the claims, and the control signal CS3 output by control unit 44 to switch S3 is an example of the "second control signal" in the claims. In the AC generating circuit 42-1, the state in which capacitor C1 and capacitor C2 are connected in parallel between the positive and negative terminals of the battery 30 is an example of the "first state" in the claims, and the state in which capacitor C1 and capacitor C2 are connected in series between the positive and negative terminals of the battery 30 is an example of the "second state" in the claims.

[0062] [Operation of the heating device]

[0063] Here, the frequency of the alternating current generated by the AC generating circuit 42-1 is considered. In order to efficiently heat the battery 30 by the heating device 40, the current waveform of the alternating current generated by the AC generating circuit 42-1 is preferably a sine wave. Moreover, from the viewpoint of controlling the AC generating circuit 42-1 to generate the alternating current, it is preferable that the duty cycle of the control signal output by the control unit 44 to the switches S1, S2 and S3 is 50%.

[0064] However, as described above, in the AC generating circuit 42-1, capacitors C1 and C2 are capacitors with equal electrostatic capacitance. Therefore, in the AC generating circuit 42-1, the overall electrostatic capacitance differs depending on whether capacitors C1 and C2 are connected in series with the battery 30 or connected in parallel with the battery 30, when considering capacitors C1 and C2 as a single capacitor. More specifically, the overall electrostatic capacitance of the AC generating circuit 42-1 when capacitors C1 and C2 are connected in series is the sum of the reciprocals of the individual capacitors' electrostatic capacitances, i.e., half the electrostatic capacitance. On the other hand, the overall electrostatic capacitance of the AC generating circuit 42-1 when capacitors C1 and C2 are connected in parallel is the sum of the individual capacitors' electrostatic capacitances, i.e., twice the electrostatic capacitance. Therefore, in the AC generating circuit 42-1, the frequency of the generated AC current differs depending on whether capacitors C1 and C2 are connected in series with the battery 30 or connected in parallel with the battery 30.

[0065] Figure 3 This is an example of an equivalent circuit of the AC generation circuit 42-1 in the first embodiment. Figure 3 In (a), an equivalent circuit is shown where capacitor C1 and capacitor C2 are connected in series with the battery 30. Figure 3 In (b), an equivalent circuit is shown where capacitor C1 and capacitor C2 are connected in parallel to the battery 30. Figure 3 In this design, the inductive component of the inductor La of the battery 30 is designated as "Ls", and the resistive component of the resistor Ra is designated as "Rs". Furthermore, the electrostatic capacitance of capacitors C1 and C2 is designated as "Cx", and the inductance of inductor L3 is designated as "Ly".

[0066] like Figure 3As shown in (a), when capacitors C1 and C2 are connected in series with the battery 30 in the AC generation circuit 42-1, inductor L3 is short-circuited by switch S3. Conversely, when capacitors C1 and C2 are connected in parallel with the battery 30 in the AC generation circuit 42-1, inductor L3 is placed between capacitors C1 and C2. Thus, by placing inductor L3 in the AC generation circuit 42-1 when capacitors C1 and C2 are connected in parallel, the waveform of the generated AC current is made closer to a sine wave, making it easier to control the switches in the control unit 44 (making the duty cycle of the control signal output by the control unit 44 closer to 50%).

[0067] <Comparative Example>

[0068] [Structure of the AC generation circuit in the comparative example]

[0069] Here, in order to explain the effect of the inductor L3 provided in the AC generating circuit 42-1, the AC generating circuit of the comparative example (hereinafter referred to as "AC generating circuit 42-C") without the inductor L3 will be explained first. Figure 4 This is a diagram showing an example of the structure of the AC generating circuit 42-C, which is a comparative example. The AC generating circuit 42-C is a structure derived from the AC generating circuit 42-1 by omitting the inductor L3. Furthermore, the connections of capacitors C1 and C2, switches S1, S2, and S3 in the AC generating circuit 42-C are equivalent to those in the AC generating circuit 42-1.

[0070] Figure 5 This is an example of the equivalent circuit of the comparative AC generating circuit 42-C. Figure 5 In (a), an equivalent circuit is shown in which capacitor C1 and capacitor C2 are connected in series with the battery 30 in the AC generating circuit 42-C. Figure 5 In (b), an equivalent circuit is shown where capacitor C1 and capacitor C2 are connected in parallel to the battery 30 in the AC generating circuit 42-C. Figure 5 Nakaya and Figure 3 Similarly, in the equivalent circuit of the AC generating circuit 42-1 shown, the inductive component of the inductance La of the battery 30 is set as "Ls", the resistive component of the resistor Ra is set as "Rs", and the electrostatic capacitance of capacitors C1 and C2 is set as "Cx".

[0071] First, refer to Figure 5 The frequency of the alternating current generated by the alternating current generating circuit 42-C is explained. In the alternating current generating circuit 42-C, as... Figure 5The impedance Z of capacitor C1 and capacitor C2 connected in series as shown in (a) can be obtained as shown in equation (1).

[0072] [Formula 1]

[0073]

[0074] Furthermore, the resonant frequency ωs in the AC generating circuit 42-C, where capacitor C1 and capacitor C2 are connected in series, can be obtained as shown in equation (2).

[0075] [Equation 2]

[0076]

[0077] On the other hand, in the AC generating circuit 42-C, such as Figure 5 The impedance Z of capacitor C1 and capacitor C2 connected in parallel as shown in (b) can be obtained as shown in equation (3).

[0078] [Formula 3]

[0079]

[0080] Furthermore, the resonant frequency ωp in the AC generating circuit 42-C, where capacitor C1 and capacitor C2 are connected in parallel, can be obtained as shown in equation (4).

[0081] [Formula 4]

[0082]

[0083] Here, when comparing the resonant frequency ωs when capacitors C1 and C2 are connected in series in AC generating circuit 42-C with the resonant frequency ωp when capacitors C1 and C2 are connected in parallel, it becomes the ratio expressed by the following formula (5).

[0084] [Formula 5]

[0085] ωs:ωp=2:1···(5)

[0086] That is, in the AC generating circuit 42-C, the resonant frequency differs depending on the difference in overall electrostatic capacitance between the case where capacitors C1 and C2 are connected in series and the case where they are connected in parallel. More specifically, the resonant frequency when capacitors C1 and C2 are connected in series is twice the resonant frequency when they are connected in parallel. Therefore, in the AC generating circuit 42-C, the current waveform of the generated AC current is not a sine wave, but rather an asymmetrical current waveform with positive and negative current values. Consequently, the generated AC current in the AC generating circuit 42-C contains a large number of harmonic components, resulting in significant noise radiation when the battery 30 is heated.

[0087] Furthermore, in order to generate the maximum amplitude AC current in the AC generation circuit 42-C, the control unit 44 must output control signals to switch the connection of capacitors C1 and C2 to the battery 30 in a series connection = "1" and a parallel connection = "2", that is, in a duty cycle of 1:2. In other words, the control unit 44 cannot generate the maximum amplitude AC current when it outputs control signals with a duty cycle of 50% to each switch.

[0088] [Operation of the heating device in the comparative example]

[0089] Figure 6 This is a diagram illustrating an example of the operating waveform (analog waveform) of the AC generating circuit 42-C in the comparative example. Figure 6 In (a), an example is shown of the control signals output by the control unit 44 to each switch, the alternating current in the alternating current generation circuit 42-C, and the change in the output voltage. Figure 6 In (b), the alternating current flowing in the alternating current generating circuit 42-C is shown.

[0090] More specifically, in Figure 6 In (a), control signals CS1, CS2, and CS3, which are output by the control unit 44 to each switch in order to generate alternating current in the alternating current generating circuit 42-C, are shown respectively. Figure 6 In (a), the corresponding switches are turned on by setting control signals CS1, CS2 and CS3 to "high" level, and turned off by setting them to "low" level. Figure 6The waveform shown in (a) is an example of a case where the control unit 44 outputs a control signal with a 50% duty cycle to each switch to generate a sinusoidal alternating current in the alternating current generating circuit 42-C. As described above, the control unit 44 may also set a dead time to make all switches non-conducting between the period when the switches are turned on and the period when the switches are turned off, but... Figure 6 In (a), it is shown that the control unit 44 controls each switch without setting a dead time.

[0091] exist Figure 6 In (a), an example is shown of the changes in the voltage V1-V0 between the terminals of the battery 30 (including inductor La), the current I-C1 flowing in capacitor C1, the current I-C2 flowing in capacitor C2, and the current I-E1 flowing in the battery 30 (including inductor La) due to the control unit 44 controlling control signals CS1, CS2, and CS3. Furthermore, in Figure 6 In (b), an example is shown of the measurement positions of voltages V1-V0 and the directions of flow of currents I-C1, I-C2 and I-E1, respectively.

[0092] like Figure 6 As shown in (a), during the series connection period PS in which the control unit 44 sets control signals CS1 and CS2 to "low" and control signal CS3 to "high", currents I-C1 and I-C2 flow from the positive region to the negative region, and consequently, 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 decreases from a positive peak voltage to a negative peak voltage, and then rises again. On the other hand, during the parallel connection period PP in which the control unit 44 sets control signals CS1 and CS2 to "high" and control signal CS3 to "low", currents I-C1 and I-C2 flow from the negative region to the positive region, and consequently, 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 immediately following the series connection period PS rises towards a positive peak voltage.

[0093] Thus, in the AC generating circuit 42-C, the control unit 44 outputs control signals to each switch to switch the connection of capacitors C1 and C2 to the battery 30 to either a series connection or a parallel connection, thereby generating AC current. However, according to Figure 6As shown in (a), the waveforms of current I-E1 and voltage V1-V0 of PS during the series connection and PP during the parallel connection also reveal that the amplitude of the AC current waveform generated by AC generation circuit 42-C is relatively small. Therefore, as described above, in order to generate AC current with maximum amplitude in AC generation circuit 42-C, control unit 44 must output control signal with a duty cycle of 1:2.

[0094] Here, in order to show the different current waveforms of the AC current caused by the duty cycle of the control signal, the operation will be explained when the control unit 44 outputs a control signal with a duty cycle of 1:2 to each switch, causing the AC generating circuit 42-C to generate an AC current with the maximum amplitude. Figure 7 This is another example of the operating waveform (analog waveform) of the AC generating circuit 42-C in the comparative example. Figure 7 In, also with Figure 6 The example of the operating waveform of the AC generating circuit 42-C in the control signal with a 50% duty cycle shown in (a) similarly illustrates the various control signals and the voltage and current that vary according to the control signals. That is, in Figure 7 The diagram shows an example of the control signal output by the control unit 44, the voltage V1-V0 between the terminals of the battery 30 (including inductor La) that varies according to the control signal, and the variations of the currents I-C1, I-C2, and I-E1 flowing in each structural element. Figure 7 The motion waveform shown is also consistent with Figure 6 The example of the operating waveform of the AC generating circuit 42-C shown is also an example of the case where the control unit 44 controls each switch without setting a dead time. Figure 7 In one example shown, the measurement positions of voltages V1-V0, and the directions of flow of currents I-C1, I-C2, and I-E1 are respectively... Figure 6 The example shown in (b) is the same.

[0095] like Figure 7 As shown, during the short series connection period PS due to the control unit 44 outputting a control signal with a duty cycle of 1:2, currents I-C1 and I-C2 flow into the positive region, and consequently, current I-E1 also flows into the positive region. As a result, the voltage V1-V0 of the AC generation circuit 42-C decreases from a positive peak voltage towards a negative peak voltage. On the other hand, during the long parallel connection period PP due to the control unit 44 outputting a control signal with a duty cycle of 1:2, currents I-C1 and I-C2 flow into the negative region, and consequently, current I-E1 also flows into the negative region. As a result, the voltage V1-V0 of the AC generation circuit 42-C increases from a negative peak voltage towards a positive peak voltage.

[0096] Thus, in the AC generation circuit 42-C, the control unit 44 outputs control signals to each switch with a duty cycle of 1:2, thereby comparing... Figure 6 (a) and Figure 7 From the waveforms of current I-E1 and voltage V1-V0 of PS during series connection and PP during parallel connection, it can be seen that a larger amplitude (maximum amplitude) AC current can be generated. However, when the control unit 44 switches the connection of capacitors C1 and C2 to the battery 30 in a duty cycle of 1:2 to either series or parallel connection, according to... Figure 7 The waveforms of current I-E1 and voltage V1-V0 of PS during the series connection and PP during the parallel connection also show that the current waveform of the AC current generated by the AC generating circuit 42-C is not a sine wave, and the amplitude is different in the positive and negative regions of AC current.

[0097] return Figure 3 The frequency of the AC current generated by AC generating circuit 42-1 will be explained. First, consider... Figure 3 The resonant frequency is shown in (a) when capacitors C1 and C2 are connected in series. In the AC generating circuit 42-1, when capacitors C1 and C2 are connected in series, inductor L3 is short-circuited by switch S3 as described above, so Ly = 0. Therefore, in the AC generating circuit 42-1, the impedance Z when capacitors C1 and C2 are connected in series is also the same as in the AC generating circuit 42-C, and can be obtained as in equation (1) above, and the resonant frequency ωs can be obtained as in equation (2) above.

[0098] Next, consider Figure 3 The resonant frequency is shown in (b) when capacitors C1 and C2 are connected in parallel. In the AC generating circuit 42-1, when capacitors C1 and C2 are connected in parallel, inductor L3 is positioned between capacitors C1 and C2 as described above. Therefore, in the AC generating circuit 42-1, the impedance Z when capacitors C1 and C2 are connected in parallel is different from that in the AC generating circuit 42-C, and can be calculated as shown in equation (6).

[0099] [Formula 6]

[0100]

[0101] Furthermore, the resonant frequency ωp in the AC generating circuit 42-1, where capacitor C1 and capacitor C2 are connected in parallel, can be obtained as shown in equation (7).

[0102] [Formula 7]

[0103]

[0104] Therefore, in AC generating circuit 42-1, in order to make the resonant frequency ωs of the capacitor C1 and capacitor C2 connected in series equal to the resonant frequency ωp of the capacitor C1 and capacitor C2 connected in parallel (as shown in equation (8)), it is sufficient that equation (9) holds.

[0105] [Formula 8]

[0106] ωs=ωp...(8)

[0107] [Formula 9]

[0108]

[0109] Therefore, the inductance Ly of inductor L3 in AC generation circuit 42-1 is sufficient as long as the following equation (10) holds.

[0110] [Formula 10]

[0111]

[0112] That is, in the AC generating circuit 42-1, if the inductance Ly of the inductor L3 is made to be one-third of the inductance component Ls of the inductance La of the battery 30, then the resonant frequency ωs in the case of series connection of capacitor C1 and capacitor C2 can be made equal to the resonant frequency ωp in the case of parallel connection of capacitor C1 and capacitor C2.

[0113] Figure 8 This is a diagram illustrating an example of the operating waveform (analog waveform) of the AC generation circuit 42-1 according to the first embodiment. Figure 8 In, with Figure 6 or Figure 7 Similarly, an example of the operating waveform of the AC generating circuit 42-C in the comparative example is shown, illustrating the various control signals and the voltage and current variations according to the control signals. That is, in Figure 8 In (a), an example is shown of the control signal output by the control unit 44, the voltage V1-V0 between the terminals of the battery 30 (including the inductor La) that varies according to the control signal, and the variations of the currents I-C1, I-C2, and I-E1 flowing in each structural element. Figure 8 In (b), an example is shown of the measurement positions of voltages V1-V0 and the directions of flow of currents I-C1, I-C2 and I-E1, respectively.

[0114] Figure 8The waveform shown in (a) is an example of a case where the control unit 44 outputs a control signal with a duty cycle of 50% to each switch in order to generate a sinusoidal alternating current in the alternating current generating circuit 42-1. Figure 8 The motion waveform shown in (a) is also similar to Figure 6 or Figure 7 The example of the operating waveform of the AC generating circuit 42-C shown in the comparative example is also an example of the case where the control unit 44 controls each switch without setting a dead time.

[0115] like Figure 8 As shown in (a), in the AC generating circuit 42-1, during the series connection period PS in which the control unit 44 sets control signals CS1 and CS2 to "low" level and control signal CS3 to "high" level, currents I-C1 and I-C2 mainly flow into the negative region, and consequently, current I-E1 also mainly flows into the negative region. Therefore, the voltage V1-V0 of the AC generating circuit 42-1 rises from a negative peak voltage towards a positive peak voltage. On the other hand, in the AC generating circuit 42-1, during the parallel connection period PP in which the control unit 44 sets control signals CS1 and CS2 to "high" level and control signal CS3 to "low" level, currents I-C1 and I-C2 mainly flow into the positive region, and consequently, current I-E1 also mainly flows into the positive region. Therefore, the voltage V1-V0 of the AC generating circuit 42-1 decreases from a positive peak voltage towards a negative peak voltage.

[0116] Thus, similarly to AC generation circuit 42-C, in AC generation circuit 42-1, control signals are output to each switch via control unit 44 to switch the connection of capacitors C1 and C2 to battery 30 to either series or parallel connection, thereby generating AC current. Furthermore, according to... Figure 8 As shown in (a), the waveforms of current I-E1 and voltage V1-V0 of PS during the series connection and PP during the parallel connection also indicate that the current waveform of the AC current generated by AC generating circuit 42-1 is similar to... Figure 6 (a) or Figure 7 Compared to the AC current waveform generated by the AC generating circuit 42-C shown, the AC current waveform is closer to a sine wave, and the difference between the absolute value of the amplitude in the positive AC current region and the absolute value in the negative AC current region is also reduced.

[0117] Thus, in the AC generation circuit 42-1, by configuring the inductor L3 between capacitors C1 and C2 when capacitors C1 and C2 are connected in parallel, the duty cycle of the control signal output by the control unit 44 can be made 50%, and the waveform of the generated AC current can be made closer to a sine wave. That is, in the AC generation circuit 42-1, an AC current with symmetrical waveforms at positive and negative current values ​​can be generated. As a result, in the AC generation circuit 42-1, the control of each switch in the control unit 44 can be made easier, and the battery 30 can be heated more efficiently by generating an AC current with a near-sine wave waveform. In other words, in the AC generation circuit 42-1, an AC current with reduced harmonic components can be generated, and the noise radiated when heating the battery 30 can be reduced.

[0118] Therefore, when the battery 30 installed in the vehicle 1 is a combination of multiple (e.g., two) batteries 30, the AC generation circuit 42-1 is more readily applicable as a structure that raises the temperature by applying (flowing) AC current to each battery 30 and reduces the overall voltage fluctuation (so-called voltage waveform ripple) output from the group of multiple batteries 30. More specifically, when the battery 30 installed in the vehicle 1 is a combination of two batteries 30, the following structure is more readily applicable: each battery 30 is connected to an AC generation circuit 42-1, and the control unit 44 controls the phase of the AC current generated by each AC generation circuit 42-1 to be staggered (staggered by 180°), thereby reducing the overall voltage fluctuation output from the group of two batteries 30.

[0119] [Another function of the heating device]

[0120] Figure 9 This is a diagram showing another example of the operating waveform (analog waveform) of the AC generating circuit 42-1 of the first embodiment. Figure 9 This is an example of a configuration where the battery 30 mounted on vehicle 1 is composed of two batteries 30 (battery 30a and battery 30b). Figure 9 In (a), the connections of the AC generating circuits 42-1 (AC generating circuits 42-1a and 42-1b) corresponding to each of the batteries 30 are shown, as well as the AC current flowing within each AC generating circuit 42-1. Figure 9 In (b), an example is shown of the control signals output by the control unit 44 to each switch, the AC current in each AC generating circuit 42-1, and the changes in the output voltage. Figure 9In the diagram, the "a" at the end of each label indicates that it corresponds to AC generation circuit 42-1a, and the "b" indicates that it corresponds to AC generation circuit 42-1b.

[0121] like Figure 9 As shown in (a), in the case of a structure consisting of two batteries 30, one battery 30a is connected to an AC generating circuit 42-1a, and the other battery 30b is connected to an AC generating circuit 42-1b. Furthermore, the control unit 44 outputs control signals to the switches of each AC generating circuit 42-1 in such a way that the phases of the AC currents generated by each AC generating circuit 42-1 are offset by 180°. Figure 9 In (b), it is shown that in order to generate a sinusoidal AC current in each AC generating circuit 42-1, the control unit 44 outputs a control signal with a duty cycle of 50% to each AC generating circuit 42-1. Figure 9 The control signal shown in (b) is also an example of the control signal when the control unit 44 controls each switch without setting a dead time.

[0122] exist Figure 9 In (a), an example is shown of the measurement position of the voltage and the direction of current flow that change in each AC generating circuit 42-1 due to the control unit 44 controlling each switch using control signals. More specifically, as an example of voltage and current corresponding to AC generating circuit 42-1a, the voltages V1-V0 between the terminals of the battery 30a (including inductor Laa), the currents I-C1a flowing in capacitor C1a and I-C2a flowing in capacitor C2a, and the current I-E1a flowing in battery 30a (including inductor Laa) are shown. Furthermore, as an example of voltage and current corresponding to AC generating circuit 42-1b, the voltages V2-V1 between the terminals of the battery 30b (including inductor Lab), the currents I-C1b flowing in capacitor C1b and I-C2b flowing in capacitor C2b, and the current I-E1b flowing in battery 30b (including inductor Lab) are shown. Moreover, in Figure 9 In (a), the voltage of the combined storage battery 30a and storage battery 30b is shown as the voltage V2-V0 at one end (V0) of the negative terminal of storage battery 30a in AC generation circuit 42-1a and one end (V2) of the positive terminal of storage battery 30b in AC generation circuit 42-1b. Furthermore, in Figure 9 In (b), an example of the changes in current and voltage in AC generating circuits 42-1a and 42-1b is shown.

[0123] like Figure 9As shown in (b), during period P1, control unit 44 sets control signals CS1a and CS2a of AC generation circuit 42-1a to a "low" level and control signal CS3a to a "high" level. Therefore, in AC generation circuit 42-1a, capacitors C1a and C2a are connected in series via inductor L3a, and... Figure 8 Similarly, during the series connection shown in (b), currents I-C1a and I-C2a flow primarily to the negative region, and consequently, current I-E1a also flows primarily to the negative region. Therefore, the voltages V1-V0 of the AC generating circuit 42-1a are related to... Figure 8 During the series connection shown in (b), PS similarly rises from a negative peak voltage to a positive peak voltage. On the other hand, during period P1, the control unit 44 sets the control signals CS1b and CS2b of the AC generation circuit 42-1b to a "high" level and the control signal CS3b to a "low" level. Thus, in the AC generation circuit 42-1b, capacitor C1b is connected in parallel with capacitor C2b, and... Figure 8 Similarly, during the parallel connection shown in (b), currents I-C1b and I-C2b flow mainly to the positive region, and thus, current I-E1b also flows mainly to the positive region. As a result, the voltage V2-V1 of the AC generating circuit 42-1b decreases from the positive peak voltage to the negative peak voltage.

[0124] After that, as Figure 9 As shown in (b), during period P2, control unit 44 sets control signals CS1a and CS2a of AC generation circuit 42-1a to "high" level and control signal CS3a to "low" level. Therefore, in AC generation circuit 42-1a, capacitor C1a and capacitor C2a are connected in parallel, and... Figure 8 During the parallel connection shown in (b) at PP, similarly, currents I-C1a and I-C2a flow mainly towards the positive region, and thus, current I-E1a also flows mainly towards the positive region. Consequently, the voltage V1-V0 of the AC generating circuit 42-1a decreases from a positive peak voltage towards a negative peak voltage. On the other hand, during period P2, the control unit 44 sets the control signals CS1b and CS2b of the AC generating circuit 42-1b to a "low" level and sets the control signal CS3b to a "high" level. Therefore, in the AC generating circuit 42-1b, capacitors C1b and C2b are connected in series via inductor L3b, and... Figure 8 During the series connection shown in (b), similarly, currents I-C1b and I-C2b flow primarily to the negative region, and consequently, current I-E1b also flows primarily to the negative region. Therefore, the voltages V2-V1 in the AC generating circuit 42-1b are... Figure 8During the series connection shown in (b), PS similarly rises from a negative peak voltage toward a positive peak voltage.

[0125] Thus, when the battery 3 installed in vehicle 1 is a combination of two batteries 30 (here, battery 30a and battery 30b), the control unit 44 outputs a control signal to control the vehicle by causing the AC generating circuit 42-1 corresponding to each battery 30 to operate in the opposite manner. Therefore, as... Figure 9 As shown in (b), the voltage variation V2-V0 of the combined system of two batteries 30 can be reduced. This is because the current waveform of the AC current generated by each AC generating circuit 42-1 is close to a symmetrical sine wave current waveform at both positive and negative current values.

[0126] [Another operation of the heating device in the comparative example]

[0127] exist Figure 4 The AC generating circuit 42-C of the comparative example shown can also be applied to the structure formed by combining two batteries 30 mounted on the battery 30 of the vehicle 1. However, since the current waveform of the AC current generated by the AC generating circuit 42-C is asymmetrical when the current value is positive and when the current value is negative, the effect of reducing the voltage fluctuation of the overall combination of the two batteries 30 is small.

[0128] Here, for comparison with AC generating circuit 42-1, an example is shown where AC generating circuit 42-C is applied to a structure consisting of two batteries 30. Figure 10 This is another example of the operating waveform of the AC generating circuit 42-C in the comparative example. Figure 10 This is an example where the AC generating circuit 42-C is connected to each battery 30 when the battery 30 installed in vehicle 1 is a combination of two batteries 30 (battery 30a and battery 30b). Regarding the operation of the AC generating circuit 42-C in this case and the control of the AC generating circuit 42-C in the control unit 44, please refer to... Figure 6 or Figure 7 The operation of the AC generating circuit 42-C shown and the control of the AC generating circuit 42-C in the control unit 44 are related to... Figure 9 The operation of the AC generating circuit 42-1 shown is considered in the same way as the control of the AC generating circuit 42-1 in the control unit 44. Therefore, the operation of the AC generating circuit 42-1 shown is omitted. Figure 10 Detailed explanation of the operation of the AC generation circuit 42-C shown and the control of the AC generation circuit 42-C in the control unit 44.

[0129] When comparing Figure 9 The voltage waveform of voltage V2-V0 shown in (b) is similar to... Figure 10 When looking at the voltage waveforms of V2-V0 shown in (b), it can be seen that compared to the case where AC generating circuit 42-C is applied to a structure composed of two batteries 30, the effect of reducing voltage fluctuations of V2-V0 is greater when AC generating circuit 42-1 is applied to a structure composed of two batteries 30.

[0130] Thus, in the heating device 40 of the first embodiment, in the AC generation circuit 42-1, an 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 and second terminals of the switch S3. Furthermore, in the heating device 40 of the first embodiment, when an AC current based on the power stored in the battery 30 is generated through the resonant operation of the inductance La of the battery 30 and at least capacitor C1, in the AC generation circuit 42-1, when capacitors C1 and C2 are connected in parallel, the inductor L3 is positioned between capacitors C1 and C2. Therefore, in the heating device 40 of the first embodiment, the waveform of the generated AC current can be made closer to a sine wave, the duty cycle of the control signal output by the control unit 44 can be closer to 50%, and the control unit 44 can easily control each switch. Therefore, in the heating device 40 of the first embodiment, the battery 30 can be heated more efficiently by the AC current with a near-sine wave current waveform generated by the AC generation circuit 42-1.

[0131] Furthermore, in the heating device 40 of the first embodiment, for example, when the battery 30 installed in the vehicle 1 is a combination of two batteries 30, the control unit 44 controls the phase of the alternating current generated by each alternating current generating circuit 42-1 to be staggered (staggered by 180°), thereby reducing the overall voltage fluctuation of the output from the combination of the two batteries 30.

[0132] <Second Implementation>

[0133] [The structure of the AC generation circuit in the heating device]

[0134] Figure 11 This diagram illustrates an example of the structure of the AC generation circuit 42 (hereinafter referred to as "AC generation circuit 42-2") included in the heating device 40 of the second embodiment. Figure 11 Also shown is a battery 30 associated with the AC generating circuit 42-2. The AC generating circuit 42-2 includes, for example, capacitor C1, capacitor C2, switch S1, switch S2, switch S31, switch S32, inductor L3, inductor L10, and inductor L20.

[0135] The AC generating circuit 42-2 is configured such that the switch S3 of the AC generating circuit 42-1 in the first embodiment is replaced by two switches, S31 and S32, and inductors L10 and L20 are added. Other structural elements of the AC generating circuit 42-2, namely capacitor C1, capacitor C2, switches S1 and S2, and inductor L3, are equivalent to those of the AC generating circuit 42-1 in the first embodiment. Inductors L10 and L20 are inductors with equal inductance. Switches S31 and S32 are also controlled, similarly to switch S3 in the AC generating circuit 42-1, to either a conducting state (connecting the two terminals, becoming a closed state) or a non-conducting state (not connecting the two terminals, becoming a closed state) based on the control signal output by the control unit 44. In the following description, the control signal output by the control unit 44 that controls switch S31 to be in an on or off state is called "control signal CS31", and the control signal that controls switch S32 to be in an on or off state is called "control signal CS32". Switches S31 and S32 can be semiconductor switching elements such as N-channel metal oxide semiconductor field-effect transistors (MOSFETs), similar to the switch S3 in the AC generation circuit 42-1.

[0136] In AC generation circuit 42-2, the first terminal of capacitor C1 is connected to the positive terminal of battery 30, and the first terminal of capacitor C2 is connected to the negative terminal of battery 30. Furthermore, in AC generation circuit 42-2, the first terminal of switch S2 is connected to the first terminal of capacitor C1, and the second terminal of switch S1 is connected to the first terminal of capacitor C2. Moreover, in AC generation circuit 42-2, the second terminal of switch S31, the second terminal of inductor L3, and the second terminal of inductor L20 are connected to the second terminal of capacitor C1, and the first terminal of switch S32, the first terminal of inductor L3, and the first terminal of inductor L10 are connected to the second terminal of capacitor C2. Furthermore, in AC generation circuit 42-2, the first terminal of inductor L20 is connected between the first terminal of switch S1 and the second terminal of switch S32, and the second terminal of inductor L10 is connected between the second terminal of switch S2 and the first terminal of switch S31.

[0137] With this structure, in the AC generating circuit 42-2, according to the control from the control unit 44, capacitor C1 and capacitor C2 are connected in parallel or in series between the positive and negative terminals of the battery 30. More specifically, the control unit 44 outputs a control signal CS1 to switch S1 to make it conduct, a control signal CS2 to switch S2 to make it conduct, a control signal CS31 to switch S31 to make it deconduct, and a control signal CS32 to switch S32 to make it deconduct, thereby connecting capacitor C1 and capacitor C2 in parallel between the positive and negative terminals of the battery 30. On the other hand, the control unit 44 outputs a control signal CS1 to switch S1 to make it non-conducting, a control signal CS2 to switch S2 to make it non-conducting, a control signal CS31 to make it conducting, and a control signal CS32 to make it conducting, thereby connecting capacitor C1 and capacitor C2 in series between the positive and negative terminals of the battery 30.

[0138] In AC generating circuit 42-2, capacitor C1 is an example of the "first capacitor" in the claims, and capacitor C2 is an example of the "second capacitor" in the claims. In AC generating circuit 42-2, the structure combining switches S1 and S2 is an example of the "parallel switching section" in the claims, and the structure combining switches S31 and S32 is an example of the "series switching section" in the claims. In AC generating circuit 42-2, switch S1 is an example of the "first switch" in the claims, switch S2 is an example of the "second switch" in the claims, switch S31 is an example of the "third switch" in the claims, and switch S32 is an example of the "fourth switch" in the claims. In AC generating circuit 42-2, inductor L3 is an example of the "first inductor" in the claims, inductor L10 is an example of the "second inductor" in the claims, and inductor L20 is an example of the "third inductor" in the claims. The control signal CS1 output by the control unit 44 to switch S1 and the control signal CS2 output to switch S2 are examples of the "first control signal" in the claims. The control signal CS31 output by the control unit 44 to switch S31 and the control signal CS32 output to switch S32 are examples of the "second control signal" in the claims. In the AC generating circuit 42-2, the state in which capacitor C1 and capacitor C2 are connected in parallel between the positive and negative terminals of the battery 30 is an example of the "first state" in the claims. The state in which capacitor C1 and capacitor C2 are connected in series between the positive and negative terminals of the battery 30 is an example of the "second state" in the claims.

[0139] [Operation of the heating device]

[0140] Figure 12 This is an example of the equivalent circuit of the AC generation circuit 42-2 in the second embodiment. Figure 12 In (a), an equivalent circuit is shown where capacitor C1 and capacitor C2 are connected in series with the battery 30. Figure 12 In (b), an equivalent circuit is shown where capacitor C1 and capacitor C2 are connected in parallel to the battery 30. Figure 12 In this design, the inductive component of the inductor La in the battery 30 is designated as "Ls", and the resistive component of the resistor Ra is designated as "Rs". Furthermore, the electrostatic capacitance of capacitors C1 and C2 is designated as "Cx", and the inductance of inductor L3 is designated as "Ly". Additionally, the inductance of inductors L10 and L20 is designated as "Lx".

[0141] In AC generation circuit 42-2, capacitors C1 and C2 are also capacitors with equal electrostatic capacitance. Therefore, similar to AC generation circuit 42-1, the overall electrostatic capacitance differs depending on whether capacitors C1 and C2 are connected in series with the battery 30 or connected in parallel with the battery 30, since they are considered as a single capacitor. Similarly, in AC generation circuit 42-2, the frequency of the generated AC current differs depending on whether capacitors C1 and C2 are connected in series with the battery 30 or connected in parallel with the battery 30. In AC generation circuit 42-2, to efficiently heat the battery 30 via the heating device 40, it is preferable that the generated AC current waveform is a sine wave, and the duty cycle of the control signals output by the control unit 44 to switches S1, S2, S31, and S32 is 50%. Here, we consider the frequency of the AC current generated by the AC generating circuit 42-2.

[0142] First of all, Figure 12 The resonant frequency shown in (a) is explained when capacitor C1 and capacitor C2 are connected in series. In the AC generation circuit 42-2, when capacitor C1 and capacitor C2 are connected in series, a circuit consisting of inductors L3, L10, and L20 is arranged between capacitor C1 and capacitor C2. Therefore, the impedance Z in the AC generation circuit 42-2 when capacitor C1 and capacitor C2 are connected in series can be obtained as shown in equation (11).

[0143] [Equation 11]

[0144]

[0145] Furthermore, in the AC generating circuit 42-2, the resonant frequency ωs when capacitors C1 and C2 are connected in series is the frequency obtained by minimizing the impedance Z and making it equal to the resistance component Rs, as calculated in equation (11) above. Therefore, for the resonant frequency ωs, the numerator of the first term on the right-hand side of equation (11) above can be zero. That is, for the resonant frequency ωs, equation (12) below can hold.

[0146] [Equation 12]

[0147]

[0148] Then, according to the above equation (12), the resonant frequency ωs can be obtained as shown in the following equation (13).

[0149] [Equation 13]

[0150]

[0151] Next, regarding Figure 12 The resonant frequency shown in (a) is explained when capacitors C1 and C2 are connected in parallel. In the AC generating circuit 42-2, when capacitors C1 and C2 are connected in parallel, an inductor L10 is connected in series between the first end of capacitor C1 and the second end of capacitor C2, an inductor L20 is connected in series between the second end of capacitor C1 and the first end of capacitor C2, and an inductor L3 is connected between inductors L10 and L20. Therefore, the impedance Z in the AC generating circuit 42-2 when capacitors C1 and C2 are connected in parallel can be obtained as shown in equation (14).

[0152] [Formula 14]

[0153]

[0154] Here, in the AC generating circuit 42-2, the resonant frequency ωp, when capacitor C1 and capacitor C2 are connected in parallel, is the frequency obtained by minimizing the impedance Z and making it equal to the resistance component Rs, as calculated in equation (14) above. Therefore, for the resonant frequency ωp, the numerator of the first term on the right-hand side of equation (14) above can be zero. That is, for the resonant frequency ωp, equation (15) below can hold.

[0155] [Formula 15]

[0156]

[0157] Then, according to the above equation (15), the resonant frequency ωp can be obtained as shown in the following equation (16).

[0158] [Formula 16]

[0159]

[0160] Here, when comparing the resonant frequency ωs and the resonant frequency ωp, the resonant frequency ωs can be expressed as shown in equation (17), and the resonant frequency ωp can be expressed as shown in equation (18).

[0161] [Equation 17]

[0162]

[0163] [Formula 18]

[0164]

[0165] Therefore, in AC generating circuit 42-2, in order to make the resonant frequency ωs of capacitor C1 and capacitor C2 connected in series equal to the resonant frequency ωp of capacitor C1 and capacitor C2 connected in parallel, the following equation (19) is valid.

[0166] [Formula 19]

[0167] 2Lx + 4Ly = Ls + 2Lx + Ly

[0168] 3Ly=Ls···(19)

[0169] Therefore, the following equation (20) holds true for the inductance Ly of inductor L3 in AC generation circuit 42-2.

[0170] [Formula 20]

[0171]

[0172] This is the same as the AC generating circuit 42-1 in the first embodiment. That is, in the AC generating circuit 42-2, if the inductance Ly of the inductor L3 is also set to one-third of the inductance component Ls of the inductance La of the battery 30, the resonant frequency ωs in the case of series connection of capacitor C1 and capacitor C2 can be made equal to the resonant frequency ωp in the case of parallel connection of capacitor C1 and capacitor C2. Therefore, in the AC generating circuit 42-2, by connecting capacitor C1 and capacitor C2 in series or in parallel, the current waveform of the generated AC current can be made closer to a sine wave, the duty cycle of the control signal output by the control unit 44 can be closer to 50%, and the control of each switch in the control unit 44 can be made easier.

[0173] Figure 13 This is a diagram illustrating an example of the operating waveform (analog waveform) of the AC generating circuit 42-2 according to the second embodiment. Figure 13 In, also with Figure 8 The example of the operating waveform of the AC generating circuit 42-1 shown also illustrates the various control signals and the voltage and current that change according to the control signals. Figure 13 In (a), an example is shown of the control signal output by the control unit 44, the voltage V1-V0 between the terminals of the battery 30 (including the inductor La) that varies according to the control signal, and the variations of the currents I-C1, I-C2, and I-E1 flowing in each structural element. Figure 13 In (b), an example is shown of the measurement positions of voltages V1-V0 and the directions of flow of currents I-C1, I-C2 and I-E1, respectively.

[0174] Figure 13 The waveform shown in (a) is also an example of a case in which the control unit 44 outputs a control signal with a duty cycle of 50% to each switch in order to generate a sinusoidal AC current in the AC generating circuit 42-2. Figure 13 The motion waveform shown in (a) is also similar to Figure 8 The example of the operating waveform of the AC generating circuit 42-1 shown is also an example of the case where the control unit 44 controls each switch without setting a dead time.

[0175] like Figure 13 As shown in (a), in the AC generating circuit 42-2, during the series connection PS where the control unit 44 sets control signals CS1 and CS2 to "low" level and control signals CS31 and CS32 to "high" level, currents I-C1 and I-C2 mainly flow into the negative region, and consequently, current I-E1 also mainly flows into the negative region. Therefore, the voltage V1-V0 of the AC generating circuit 42-2 rises from a negative peak voltage towards a positive peak voltage. On the other hand, in the AC generating circuit 42-2, during the parallel connection PP where the control unit 44 sets control signals CS1 and CS2 to "high" level and control signals CS31 and CS32 to "low" level, currents I-C1 and I-C2 mainly flow into the positive region, and consequently, current I-E1 also mainly flows into the positive region. Therefore, the voltage V1-V0 of the AC generating circuit 42-2 decreases from a positive peak voltage towards a negative peak voltage.

[0176] Thus, similarly to AC generation circuit 42-1, in AC generation circuit 42-2, control signals are output to each switch via control unit 44 to switch the connection of capacitors C1 and C2 to battery 30 to either series or parallel connection, thereby generating AC current. Furthermore, according to... Figure 13As shown in (a), the waveforms of current I-E1 and voltage V1-V0 of PS during the series connection and PP during the parallel connection also indicate that the current waveform of the AC current generated by AC generating circuit 42-2 is similar to... Figure 8 Compared to the current waveform of the AC current generated by the AC generating circuit 42-1 shown in (a), it is closer to a sine wave waveform, and the difference between the absolute value of the amplitude in the region where the AC current is positive and the absolute value in the region where the AC current is negative is also reduced.

[0177] Thus, in the structure of AC generation circuit 42-2, similar to AC generation circuit 42-1, the duty cycle of the control signal output by control unit 44 can be made 50%, and the current waveform of the generated AC current can be made closer to a sine wave. Therefore, in AC generation circuit 42-2, similar to AC generation circuit 42-1, the control of each switch in control unit 44 can be made easier, and the battery 30 can be heated more efficiently by generating an AC current with a near-sine wave waveform. Furthermore, in AC generation circuit 42-2, by generating an AC current that is even closer to a sine wave, i.e., with further reduced harmonic components, the noise radiated when heating the battery 30 can be further reduced.

[0178] [Another function of the heating device]

[0179] The AC generating circuit 42-2 is also applicable to the structure formed by combining multiple (e.g., two) batteries 30, which is mounted on the vehicle 1, just like the AC generating circuit 42-1. Figure 14 This is another example of the operating waveform (analog waveform) of the AC generating circuit 42-2 of the second embodiment. Figure 14 also with Figure 9 Another example of the operating waveform of the AC generating circuit 42-1 shown is an example of connecting the AC generating circuit 42-2 to each battery 30 when the battery 30 mounted on the vehicle 1 is a combination of two batteries 30 (battery 30a and battery 30b). Figure 14 In (a), the connections of the AC generating circuits 42-2 (AC generating circuits 42-2a and AC generating circuits 42-2b) corresponding to each of the batteries 30 are also shown, as well as the AC current flowing within each AC generating circuit 42-2. Figure 14 In (b), an example is shown of the control signals output by the control unit 44 to each switch, the AC current in each AC generating circuit 42-2, and the changes in the output voltage.

[0180] like Figure 14As shown in (a), in the case of a structure consisting of two batteries 30, AC generating circuit 42-2a is connected to battery 30a, and AC generating circuit 42-2b is connected to battery 30b. Furthermore, the control unit 44 outputs control signals to the switches of each AC generating circuit 42-2 in such a way that the phases of the AC currents generated by each AC generating circuit 42-2 are offset by 180°. Figure 14 In (b), it is also shown that in order to generate sinusoidal AC current in each AC generating circuit 42-2, the control unit 44 outputs a control signal with a duty cycle of 50% to each AC generating circuit 42-2. Figure 14 The control signal shown in (b) is also an example of the control signal when the control unit 44 controls each switch without setting a dead time.

[0181] Regarding the operation of the AC generation circuit 42-2 in this situation and the control of the AC generation circuit 42-2 in the control unit 44, please refer to... Figure 13 The operation of the AC generating circuit 42-2 shown and the control of the AC generating circuit 42-2 in the control unit 44 are related to... Figure 9 The operation of the AC generating circuit 42-1 shown is considered in the same way as the control of the AC generating circuit 42-1 in the control unit 44. Therefore, the operation of the AC generating circuit 42-1 shown is omitted. Figure 14 Detailed description of the operation of the AC generation circuit 42-2 shown and the control of the AC generation circuit 42-2 in the control unit 44.

[0182] When comparing Figure 14 The voltage waveform of voltage V2-V0 shown in (b) is similar to... Figure 9 When the voltage waveforms of voltage V2-V0 shown in (b) are examined, it can be seen that compared to the case where AC generating circuit 42-1 is applied to a structure consisting of two batteries 30, the voltage variation of voltage V2-V0 is less when AC generating circuit 42-2 is applied to a structure consisting of two batteries 30.

[0183] Thus, in the heating device 40 of the second embodiment, the AC generating circuit 42-2 includes an inductor L3 whose inductance Ly is one-third of the inductance component Ls of the inductance La of the battery 30, and inductors L10 and L20 with the same inductance Lx. Furthermore, in the heating device 40 of the second embodiment, when an AC current based on the power stored in the battery 30 is generated through the resonant operation of the inductance La of the battery 30 and at least capacitor C1, in the AC generating circuit 42-2, different circuits composed of inductors L3, L10, and L20 are arranged between capacitors C1 and C2, whether capacitors C1 and C2 are connected in series or in parallel. Therefore, in the heating device 40 of the second embodiment, the current waveform of the generated AC current can be made closer to a sine wave, and the duty cycle of the control signal output by the control unit 44 can be close to 50%, making it easier for the control unit 44 to control each switch. Therefore, in the heating device 40 of the second embodiment, the battery 30 can be heated more efficiently by the alternating current with a current waveform that is closer to a sine wave generated by the alternating current generation circuit 42-2.

[0184] Furthermore, in the heating device 40 of the second embodiment, similarly to the heating device 40 of the first embodiment, for example, when the battery 30 mounted on the vehicle 1 is a structure composed of two batteries 30, the control unit 44 controls the phase of the alternating current generated by each alternating current generating circuit 42-2 to be staggered (staggered by 180°), thereby reducing the overall voltage fluctuation of the output from the group of two batteries 30.

[0185] Here, the differences in the characteristics of the alternating 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 explained. Figure 15 This is a graph comparing the characteristics of the alternating current generated by alternating current generating circuits 42 (AC generating circuits 42-C, 42-1, and 42-2). Figure 15 In (a), the characteristic of the ratio of harmonic components contained in the current waveform of the AC current generated by each AC generation circuit 42 is shown when the fundamental component of the AC current generated by each AC generation circuit 42 is normalized to "1". Figure 15 In (b), the characteristics of harmonic distortion in the current waveforms of the alternating current generated by each alternating current generating circuit 42 are shown. Figure 15 In comparison Figure 7 The current I-E1 in the AC generating circuit 42-C shown is... Figure 8The current I-E1 of the AC generating circuit 42-1 shown, and Figure 13 The AC current characteristics of the currents I-E1 in the AC generating circuit 42-2 shown are as follows.

[0186] like Figure 15 As shown in (a), when the fundamental component is set to "1", the ratios of the second, third, fourth, and fifth harmonics are highest in the current I-E1 generated by AC generation circuit 42-C, and lower in the current I-E1 generated by AC generation circuits 42-1 and 42-2. In particular, the ratios of the third to fifth harmonics are lower in AC generation circuits 42-1 and 42-2. Furthermore, as... Figure 15 As shown in (b), the harmonic distortion in the current waveform of the current I-E1 generated by each AC generating circuit 42 is the highest in the current I-E1 generated by AC generating circuit 42-C, and decreases in the order of current I-E1 generated by AC generating circuit 42-1 and current I-E1 generated by AC generating circuit 42-2.

[0187] Therefore, in AC generation circuits 42-1 and 42-2, compared to AC generation circuit 42-C, a current I-E1 (AC current) with reduced harmonic components and harmonic distortion can be generated. This is because in AC generation circuits 42-1 and 42-2, by incorporating inductor L3, the waveform of the generated current I-E1 (AC current) becomes a waveform closer to a sine wave. Furthermore, it can be seen that AC generation circuit 42-2 can generate a current I-E1 (AC current) with less harmonic distortion than AC generation circuit 42-1. This is because, in AC generation circuit 42-2, by also incorporating inductors L10 and L20, the waveform of the generated current I-E1 (AC current) becomes a waveform even closer to a sine wave than the current waveform I-E1 (AC current) generated by AC generation circuit 42-1.

[0188] As described above, in the heating device 40 of each embodiment, the AC generating circuit 42 includes an inductor L3 whose inductance Ly is one-third of the inductance component Ls of the inductance La of the battery 30. Furthermore, in the heating device 40 of each embodiment, by switching the connection of capacitors C1 and C2 of the AC generating circuit 42 to the battery 30 to a series connection or a parallel connection, an AC current based on the power stored in the battery 30 is generated by the resonant operation of alternately exchanging the magnetic energy stored in the inductance La of the battery 30 and the electrostatic energy stored in at least capacitor C1. At this time, in the heating device 40 of each embodiment, at least when capacitors C1 and C2 of the AC generating circuit 42 are connected in parallel to the battery 30, an inductor L3 is placed between capacitors C1 and C2. Therefore, in the heating device 40 of each embodiment, the current waveform of the AC current generated by the AC generating circuit 42 becomes a current waveform that is closer to a sine wave. Therefore, in the heating device 40 of each embodiment, the battery 30 can be heated more efficiently by using an alternating current with a near-sinusoidal current waveform generated by the alternating current generation circuit 42. Consequently, in the vehicle 1 employing the heating device 40 of each embodiment, the battery 30 can be used at a suitable temperature, and the degradation of the battery 30's charging and discharging performance can be suppressed. Furthermore, in the vehicle 1 employing the heating device 40 of each embodiment, the alternating current generated by the alternating current generation circuit 42 contains fewer harmonic components, thus reducing the noise radiated when heating the battery 30.

[0189] In the heating device 40 of each embodiment described above, it is explained that the inductance Ly of the inductor L3 of the AC generating circuit 42 (AC generating circuit 42-1, AC generating circuit 42-2) is one-third of the inductance component Ls of the inductance La of the battery 30. However, it is anticipated that even among batteries 30 of the same type, the characteristics of the inductance component Ls of the inductance La of the battery 30 may differ. Furthermore, it is anticipated that the wiring portion connecting the AC generating circuit 42 and the battery 30 also includes an inductance component. Therefore, in the heating device 40 of each embodiment, the inductance Ly of the inductor L3 of the AC generating circuit 42 may be set to a value that takes into account the deviation of 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 heating device 40 of each embodiment, if the current waveform of the alternating current generated by the alternating current generating circuit 42 can be considered as a sine wave (the range in which a substantial effect is obtained), then the inductance Ly of the inductor L3 can be set to a value with a certain amplitude that is one-third of the inductance component Ls of the inductance La of the battery 30. In other words, in the heating device 40 of each embodiment, the inductance Ly of the inductor L3 of the alternating current generating circuit 42 can be set to a value that is approximately one-third of the substantial inductance component Ls of the inductance La of the battery 30. For example, in the heating device 40 of each embodiment, the inductance Ly of the inductor L3 of the alternating current generating circuit 42 can also be set to a value with an amplitude in the range of one-quarter to two-fifths of the inductance component Ls of the inductance La of the battery 30.

[0190] In the heating device 40 of each embodiment described above, the case where the duty cycle of the control signal output by the control unit 44 to each switch is set to 50% is explained. However, as described above, the control unit 44 may also control the switches by setting a dead time between the period when the switch is in the conducting state and the period when the switch is in the non-conducting state, so that all switches are in the non-conducting state. For example, in the heating device 40 of each embodiment, the dead time may be set by setting the duty cycle of the control signal output by the control unit 44 to each switch to a value that can be considered approximately 50% (for example, a specified value between 45% and 55%), and the control signal is output to each switch to switch the connection of capacitor C1 and capacitor C2 to the battery 30 from parallel connection to series connection or from series connection to parallel connection.

[0191] According to the heating device 40 of the embodiments described above, the AC generating circuit 42 heats the battery 30 by generating an AC current based on the power stored in the battery 30 having an inductance La. The AC generating circuit 42 includes: a capacitor C1, the first terminal of which is connected to the positive terminal of the battery 30; a capacitor C2, the first terminal of which is connected to the negative terminal of the battery 30; and a parallel switch unit that, according to a first control signal (e.g., control signal CS1 and control signal CS2), connects the second terminal of capacitor C1 to the second terminal of capacitor C2. The first terminal connection connects the first terminal of capacitor C1 to the second terminal of capacitor C2, thereby connecting capacitor C1 and capacitor C2 in parallel to the battery 30. A series switch connects the second terminal of capacitor C1 to the second terminal of capacitor C2 according to a second control signal (e.g., control signal CS3), thereby connecting capacitor C1 and capacitor C2 in series to the battery 30. An inductor L3 is connected between the two terminals of the series switch. Thus, the heating device 40 enables the battery 30 used in the vehicle 1 to be heated more efficiently. Therefore, in the vehicle 1 equipped with the heating device 40 of each embodiment, the battery 30 can be used at a suitable temperature, suppressing the decline in the charging and discharging performance of the battery 30. Thus, in the vehicle 1 equipped with the heating device 40 of each embodiment, the durability and other commercial properties of the vehicle 1 can be improved. Therefore, in the vehicle 1 equipped with the heating device 40 of each embodiment, energy efficiency is improved, and it is expected to contribute to mitigating the adverse impact on the Earth's environment.

[0192] In the various embodiments described above, the following structure is described: the control device 100 controls the starting or stopping of the heating device 40, and the control unit 44 controls the switches of the AC generating circuit 42 to be in an on or off state. The operation of the control unit 44 can also be implemented by executing a program through a hardware processor such as a CPU provided with the control unit 44. The function of the control device 100 can also include the function of the control unit 44 described above. In this case, the control unit 44 can be omitted in the heating device 40.

[0193] The embodiments described above illustrate the methods for implementing the present invention, but the present invention is not limited to these embodiments in any way, and various modifications and substitutions can be applied without departing from the spirit of the present invention.

Claims

1. An AC generating circuit that heats a storage medium by generating an AC current based on electricity stored in the storage medium, the storage medium having an inductive component, wherein, The AC generating circuit includes: A first capacitor, the first end of which is connected to the positive terminal side of the energy storage body; A second capacitor, the first end of which is connected to the negative terminal side of the energy storage body; The parallel switching unit connects the second terminal of the first capacitor to the first terminal of the second capacitor and connects the first terminal of the first capacitor to the second terminal of the second capacitor according to the first control signal, thereby connecting the first capacitor and the second capacitor in parallel to the energy storage body. A series switch section, which connects the second terminal of the first capacitor to the second terminal of the second capacitor according to a second control signal, thereby connecting the first capacitor and the second capacitor in series in the energy storage body; and An inductor is connected between the two terminals of the series switch section.

2. The AC generating circuit according to claim 1, wherein, The parallel switch section has: A first switch, wherein a first terminal of the first switch is connected to a second terminal of the first capacitor, and a second terminal of the first switch is connected to a first terminal of the second capacitor; as well as A second switch, wherein the first terminal of the second switch is connected to the first terminal of the first capacitor, and the second terminal of the second switch is connected to the second terminal of the second capacitor. The series switch section includes a third switch, the first terminal of which is connected to the second terminal of the second capacitor, and the second terminal of which is connected to the second terminal 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.

3. The AC generating circuit according to claim 2, wherein, The inductance of the inductor is approximately one-third of the inductance component.

4. The AC generating circuit according to claim 1, wherein, The parallel switch section has: A first switch, wherein a first terminal of the first switch is connected to the second terminal of the first capacitor, and a second terminal of the first switch is connected to the first terminal of the second capacitor; as well as A second switch, wherein the first terminal of the second switch is connected to the first terminal of the first capacitor, and the second terminal of the second switch is connected to the second terminal of the second capacitor. The series switch section has: A third switch, the first terminal of which is connected to the second terminal of the second switch, and the second terminal of which is connected to the second terminal of the first capacitor; as well as A fourth switch, the first terminal of which is connected to the second terminal of the second capacitor, and the second terminal of which is connected to the first terminal of the first switch. The inductor has: A first inductor, the first end of which is connected to the first terminal of the fourth switch, and the second end of which is connected to the second terminal of the third switch; A second inductor, the first end of which is connected to the first end of the first inductor, and the second end of which is connected between the second terminal of the second switch and the first terminal of the third switch; as well as A third inductor, the first end of which is connected between the first terminal of the first switch and the second terminal of the fourth switch, and the second end of which is connected to the second end of the first inductor.

5. The AC generating circuit according to claim 4, wherein, The inductance of the first inductor is approximately one-third of the inductance component.

6. The AC generating circuit according to claim 5, wherein, The inductance of the second inductor is equal to the inductance of the third inductor.

7. The AC generating circuit according to claim 1, wherein, The inductance component includes the inductance component of the wiring portion between the energy storage element and the AC generating circuit.

8. The AC generating circuit according to claim 1, wherein, The first capacitor and the second capacitor have the same electrostatic capacitance.

9. A heating device comprising: The AC generating circuit according to any one of claims 1 to 8; and The control unit outputs a signal with a predetermined duty cycle that enables the parallel switch section to be in a conducting or non-conducting state as the first control signal, and outputs a signal with the predetermined duty cycle that enables the series switch section to be in a conducting or non-conducting state as the second control signal. The first and second states are alternately switched using the first and second control signals. The first state is a state in which the parallel switch section is turned on and the series switch section is turned off, and the second state is a state in which the parallel switch section is turned off and the series switch section is turned on.

10. The heating device according to claim 9, wherein, The specified duty cycle is approximately 50%.

11. The heating device according to claim 9, wherein, The energy storage device is configured to connect multiple batteries in series, and the multiple batteries are respectively connected to the AC generating circuit.

12. The heating device according to claim 11, wherein, The control unit controls the AC currents generated by the plurality of AC generating circuits in such a way that the phases of the AC currents generated by them are staggered by 180°.

13. The heating device according to claim 9, wherein, During the switching between the first state and the second state, the control unit sets a dead time that makes both the parallel switch and the series switch non-conductive.

14. The heating device according to claim 13, wherein, The specified duty cycle is in the range of 45% to 55%, and the dead time is set by this duty cycle.

15. The heating device according to claim 9, wherein, In the second state, the series switch short-circuits the inductor.

16. The heating device according to claim 9, wherein, In the first state, the inductor is disposed between the first capacitor and the second capacitor.

17. The heating device according to claim 9, wherein, The control unit controls the parallel switch section and the series switch section without setting a dead time that makes both the parallel switch section and the series switch section non-conducting.

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