Temperature raising device, control method of temperature raising device, and storage medium

Abstract

This invention provides a heating device, a control method for the heating device, and a storage medium that improve energy efficiency by heating a secondary battery more efficiently. The heating device includes an AC generation circuit and a control unit. The AC generation circuit comprises: 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 connects the first and second capacitors in parallel with the storage medium; and a series switch unit that connects the first and second capacitors in series with the storage medium. The control unit alternately switches between a first state where the parallel switch unit is in a conducting state and the series switch unit is in a non-conducting state, and a second state where the parallel switch unit is in a non-conducting state and the series switch unit is in a conducting state.

Description

Technical Field

[0001] This invention relates to a heating device, a control method for the heating device, and a storage medium. Background Technology

[0002] Efforts to mitigate adverse environmental impacts (such as NOx and SOx reductions, and CO2 reductions) are progressing steadily. Therefore, in recent years, from the perspective of improving the global environment and reducing CO2, there has been increasing attention on electric vehicles that operate at least through an electric motor, such as hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs), which are powered by electricity supplied by a battery (secondary battery). 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 the charge and discharge performance of a secondary battery decreases when the operating temperature drops below a suitable range. However, by raising the operating temperature of the secondary battery to a suitable level, the decline in charge and discharge performance can be suppressed.

[0003] Regarding this situation, 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] The problem to be solved by the present invention

[0005] However, in the existing technology, it is sometimes impossible to heat up the secondary battery efficiently.

[0006] This invention was made based on the understanding of the above-mentioned problems, and one of its objectives is to provide a heating device, a control method for the heating device, and a storage medium that can improve energy efficiency by heating the secondary battery more efficiently.

[0007] Solution for solving the problem

[0008] The heating device, the control method of the heating device, and the storage medium of the present invention adopt the following structure.

[0009] (1): A heating device according to one aspect of the present invention includes an AC generating circuit and a control unit. The AC generating circuit generates an AC current based on the power stored in a storage battery. The storage battery has an inductive component. The AC generating circuit includes: a first capacitor, the first terminal of which is connected to the positive terminal of the storage battery; a second capacitor, the first terminal of which is connected to the negative terminal of the storage battery; a parallel switch unit that 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 with the storage battery; and a series switch unit that connects the second terminal of the first capacitor to the second terminal of the second capacitor. The second end is connected, thereby connecting the first capacitor and the second capacitor in series with the energy storage body. The control unit alternately switches between a first state where the parallel switch is turned on and the series switch is turned off, and a second state where the parallel switch is turned off and the series switch is turned on. When the parallel switch is turned on from off to on, the control unit turns the parallel switch on from off to on after turning the series switch off. When the series switch is turned on from off to on, the control unit turns the series switch on from off to on after turning the parallel switch off.

[0010] (2): Based on the above (1) scheme, the parallel switch section and the series switch section each have at least one semiconductor switch section, and the semiconductor switch section is formed by connecting semiconductor switch elements controlled by the control section to the diode in parallel.

[0011] (3): Based on the above (2) scheme, either or both of the parallel switch section and the series switch section have two semiconductor switch sections connected in series, and the diodes of the two semiconductor switch sections are in opposite directions.

[0012] (4): Based on the above (2) scheme, the parallel switch section and the series switch section have a first semiconductor switch section and a second semiconductor switch section connected in series as the semiconductor switch section, and the diodes of the first semiconductor switch section and the second semiconductor switch section are in opposite directions.

[0013] (5): Based on the above (4) solution, when the control unit switches from the state of connecting the first capacitor and the second capacitor in parallel with the energy storage body to the state of connecting the first capacitor and the second capacitor in series with the energy storage body by setting the parallel switch to the on state, after making either the first semiconductor switch or the second semiconductor switch of the series switch to the on state, and while keeping either the first semiconductor switch or the second semiconductor switch of the parallel switch to the on state, it switches to the state of connecting the first capacitor and the second capacitor in series with the energy storage body, so that the current flows in the parallel switch. The current flowing through the series switch can be returned. When the control unit switches from a state in which the first capacitor and the second capacitor are connected in series with the energy storage body to a state in which the first capacitor and the second capacitor are connected in parallel with the energy storage body by setting the series switch to the on state, after setting either the first semiconductor switch or the second semiconductor switch of the parallel switch to the on state, and after keeping either the first semiconductor switch or the second semiconductor switch of the series switch in the on state, it switches to a state in which the first capacitor and the second capacitor are connected in parallel with the energy storage body, so that the current flowing through the series switch can be returned.

[0014] (6): Based on any of the above schemes (1) to (5), the control unit controls the conduction and non-conducting states of the parallel switch unit and the series switch unit respectively based on the voltage value of the first capacitor or the voltage value of the second capacitor.

[0015] (7): Based on any of the above schemes (1) to (6), the control unit controls the conduction and non-conductivity states of the parallel switch and the series switch based on the voltage values ​​of the positive and negative terminals of the energy storage body.

[0016] (8): Based on any of the above schemes (1) to (7), the control unit controls the conduction and non-conducting states of the parallel switch and the series switch based on the voltage values ​​at both ends of the parallel switch or the series switch when they are in a non-conducting state.

[0017] (9): Based on any of the above schemes (1) to (8), the control unit controls the conduction state and non-conducting state of the parallel switch section and the series switch section respectively based on the current value of the AC current flowing in the parallel switch section or the series switch section.

[0018] (10): Based on any of the above schemes (1) to (9), the control unit controls the conduction state and non-conducting state of the parallel switch unit and the series switch unit respectively at a predetermined timing based on the alternating current.

[0019] (11): Based on the above (10) scheme, the specified timing is determined based on the period or duty cycle of the alternating current.

[0020] (12): In a control method for a heating device according to one aspect of the present invention, the heating device includes an AC generating circuit and a control unit. The AC generating circuit generates an AC current based on the power stored in a storage battery. The storage battery has an inductive component. The AC generating circuit includes: a first capacitor, the first terminal of which is connected to the positive terminal of the storage battery; a second capacitor, the first terminal of which is connected to the negative terminal of the storage battery; a parallel switch unit that 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 with the storage battery; and a series switch unit that connects the second terminal of the first capacitor to the second terminal of the second capacitor. The first capacitor and the second capacitor are connected in series with the energy storage body. The control unit alternately switches between a first state where the parallel switch is turned on and the series switch is turned off, and a second state where the parallel switch is turned off and the series switch is turned on. In the control method of the heating device, the computer of the control unit performs the following processing: when the parallel switch is turned on from the off state, after the series switch is turned off from the on state, the parallel switch is turned on from the off state; and when the series switch is turned on from the off state, after the parallel switch is turned off from the on state, the series switch is turned on from the off state.

[0021] (13): In a control method for a heating device according to one aspect of the present invention, the heating device includes an AC generating circuit and a control unit. The AC generating circuit generates an AC current based on the power stored in a storage battery. The storage battery has an inductive component. The AC generating circuit includes: a first capacitor, the first terminal of which is connected to the positive terminal of the storage battery; a second capacitor, the first terminal of which is connected to the negative terminal of the storage battery; and a parallel switch unit that 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 to the storage battery. The system comprises: a parallel connection of electrical components; and a series switch that 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 with the energy storage body. The control unit alternately switches between a first state in which the parallel switch is turned on and the series switch is turned off, and a second state in which the parallel switch is turned off and the series switch is turned on. The parallel switch and the series switch each include at least one semiconductor switch, which is formed by connecting semiconductor switching elements controlled by the control unit to be in an on / off state in parallel with diodes. The parallel switch section and the series switch section each have a first semiconductor switch section and a second semiconductor switch section connected in series as semiconductor switch sections. The diodes in the first semiconductor switch section and the second semiconductor switch section are in opposite directions. In the control method of the heating device, the computer of the control unit performs the following processing: when the parallel switch section is turned from a non-conducting state to a conducting state, after the series switch section is turned from a conducting state to a non-conducting state, the parallel switch section is turned from a non-conducting state to a conducting state; when the series switch section is turned from a non-conducting state to a conducting state, after the parallel switch section is turned from a conducting state to a non-conducting state, the series switch section is turned from a non-conducting state to a conducting state. The conduction state becomes the conduction state; when the parallel switch section is set to the conduction state and the state of connecting the first capacitor and the second capacitor in parallel with the energy storage body is switched to the state of connecting the first capacitor and the second capacitor in series with the energy storage body, after either the first semiconductor switch section or the second semiconductor switch section of the series switch section is made to the conduction state, while either the first semiconductor switch section or the second semiconductor switch section of the parallel switch section is kept to the conduction state, the state of connecting the first capacitor and the second capacitor in series with the energy storage body is switched, so that the current flowing in the parallel switch section can flow back;And when switching from a state where the first capacitor and the second capacitor are connected in series with the energy storage body to a state where the first capacitor and the second capacitor are connected in parallel with the energy storage body by setting the series switch to the on state, after setting either the first semiconductor switch or the second semiconductor switch of the parallel switch to the on state, while keeping either the first semiconductor switch or the second semiconductor switch of the series switch in the on state, switching to a state where the first capacitor and the second capacitor are connected in parallel with the energy storage body, so that the current flowing in the series switch can flow back.

[0022] (14): In one aspect of the present invention, a storage medium stores a program that controls a heating device. The heating device includes an AC generating circuit and a control unit. The AC generating circuit generates an AC current based on the power stored in a storage battery. The storage battery has an inductive component. The AC generating circuit includes: a first capacitor, the first terminal of which is connected to the positive terminal of the storage battery; a second capacitor, the first terminal of which is connected to the negative terminal of the storage battery; a parallel switch unit that 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 with the storage battery; and a series switch unit that connects the second terminal of the first capacitor to the second terminal of the second capacitor. The second terminals of the two capacitors are connected, thereby connecting the first capacitor and the second capacitor in series with the energy storage body. The control unit alternately switches between a first state where the parallel switch is turned on and the series switch is turned off, and a second state where the parallel switch is turned off and the series switch is turned on. The program causes the computer of the control unit to perform the following processing: when the parallel switch is turned on from the off state, after the series switch is turned off from the on state, the parallel switch is turned on from the off state; and when the series switch is turned on from the off state, after the parallel switch is turned off from the on state, the series switch is turned on from the off state.

[0023] (15): In one aspect of the present invention, a storage medium stores a program that controls a heating device. The heating device includes an AC generating circuit and a control unit. The AC generating circuit generates an AC current based on the power stored in a storage battery. The storage battery has an inductive component. The AC generating circuit includes: a first capacitor, the first terminal of which is connected to the positive terminal of the storage battery; a second capacitor, the first terminal of which is connected to the negative terminal of the storage battery; and a parallel switch unit that 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 enabling the first capacitor and the storage battery to... The second capacitor is connected in parallel with the energy storage body; and a series switch 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 with the energy storage body. The control unit alternately switches between a first state where the parallel switch is in a conducting state and the series switch is in a non-conducting state, and a second state where the parallel switch is in a non-conducting state and the series switch is in a conducting state. The parallel switch and the series switch each have at least one semiconductor switch, and the semiconductor switch is a diode controlled by the control unit to switch between an on and off state. The parallel switching section and the series switching section are connected in parallel. The parallel switching section and the series switching section each have a first semiconductor switching section and a second semiconductor switching section connected in series as semiconductor switching sections. The diodes of the first semiconductor switching section and the second semiconductor switching section are in opposite directions. The program causes the computer of the control unit to perform the following processing: when the parallel switching section is turned from a non-conducting state to a conducting state, after the series switching section is turned from a conducting state to a non-conducting state, the parallel switching section is turned from a non-conducting state to a conducting state; when the series switching section is turned from a non-conducting state to a conducting state, after the parallel switching section is turned from a conducting state to a non-conducting state, the series switching section is turned from a non-conducting state to a conducting state. The conduction state becomes the conduction state; when the parallel switch section is set to the conduction state and the state of connecting the first capacitor and the second capacitor in parallel with the energy storage body is switched to the state of connecting the first capacitor and the second capacitor in series with the energy storage body, after either the first semiconductor switch section or the second semiconductor switch section of the series switch section is made to the conduction state, while either the first semiconductor switch section or the second semiconductor switch section of the parallel switch section is kept to the conduction state, the state of connecting the first capacitor and the second capacitor in series with the energy storage body is switched, so that the current flowing in the parallel switch section can flow back;And when switching from a state where the first capacitor and the second capacitor are connected in series with the energy storage body to a state where the first capacitor and the second capacitor are connected in parallel with the energy storage body by setting the series switch to the on state, after setting either the first semiconductor switch or the second semiconductor switch of the parallel switch to the on state, while keeping either the first semiconductor switch or the second semiconductor switch of the series switch in the on state, switching to a state where the first capacitor and the second capacitor are connected in parallel with the energy storage body, so that the current flowing in the series switch can flow back.

[0024] Invention Effects

[0025] According to the schemes (1) to (15) above, energy efficiency can be improved by making the secondary battery heat up more efficiently. Attached Figure Description

[0026] Figure 1 This is a diagram illustrating an example of the structure of a vehicle employing the heating device described in the embodiment.

[0027] Figure 2 This is an example of the equivalent circuit of a vehicle's battery.

[0028] Figure 3 This diagram illustrates an example of the structure of the AC generation circuit included in the heating device of the first embodiment.

[0029] Figure 4 This is a diagram showing an example of the operating waveform of the control and AC generation circuit of the control unit in the first embodiment.

[0030] Figure 5 This is a diagram illustrating an example of the path of alternating current flowing within the alternating current generation circuit of the first embodiment.

[0031] Figure 6 This is another example of the operating waveform of the control and AC generation circuit of the control unit in the first embodiment.

[0032] Figure 7 This is a diagram illustrating another example of the path of alternating current flowing within the alternating current generation circuit of the first embodiment.

[0033] Figure 8 This diagram illustrates an example of the structure of the AC generation circuit included in the heating device of the second embodiment.

[0034] Figure 9 This is a diagram showing an example of the operating waveform of the control and AC generation circuit of the control unit in the second embodiment.

[0035] Figure 10 This is a diagram illustrating an example of the path of alternating current flowing within the alternating current generation circuit of the second embodiment.

[0036] Figure 11 This diagram illustrates an example of the structure of the AC generation circuit included in the heating device of the third embodiment.

[0037] Figure 12 This is a diagram showing an example of the operating waveform of the control and AC generation circuit of the control unit in the third embodiment.

[0038] Figure 13 This is a diagram illustrating an example of the path of alternating current flowing within the alternating current generation circuit of the third embodiment.

[0039] Figure 14 This is a graph comparing the amplitude characteristics of the AC current generated by the AC generating circuit.

[0040] Figure 15 This diagram illustrates an example of the structure of the AC generation circuit included in the heating device of the fourth embodiment.

[0041] Figure 16 This is a diagram showing an example of the operating waveform of the control and AC generation circuit of the control unit in the fourth embodiment.

[0042] Figure 17 This is a diagram illustrating an example of the path of alternating current flowing within the alternating current generation circuit of the fourth embodiment.

[0043] Figure 18 This is a graph comparing the amplitude characteristics of the AC current generated by the AC generating circuit.

[0044] Figure 19 This is another example of the operating waveform of the control and AC generation circuit of the control unit in the fourth embodiment.

[0045] Figure 20 This diagram illustrates an example of the structure of the AC generation circuit included in the heating device of the fifth embodiment.

[0046] Figure 21 This is a diagram showing an example of the operating waveform of the control and AC generation circuit of the control unit in the fifth embodiment.

[0047] Figure 22 This is a diagram illustrating an example of the path of alternating current flowing within the alternating current generation circuit of the fifth embodiment.

[0048] Figure 23 This is a graph comparing the amplitude characteristics and losses of the AC current generated by the AC generating circuit.

[0049] Figure 24 This is a circuit diagram illustrating an example of the circuit structure of the control unit.

[0050] Figure 25 This is an example of a timing diagram showing the timing of the gate signals generated by the control unit. Detailed Implementation

[0051] Hereinafter, embodiments of the heating device, the control method of the heating device, and the storage medium of the present invention will be described with reference to the accompanying drawings.

[0052] [Vehicle Structure]

[0053] Figure 1 This diagram illustrates an example of the structure of a vehicle employing the heating device described in the embodiment. Vehicle 1 is a hybrid electric vehicle (HEV) (hereinafter simply referred to as "vehicle") that travels by a combination of driving based on an electric motor (electric motor) powered by electricity supplied from a driving battery (secondary battery) or by driving based on an internal combustion engine that uses fuel as its energy source, such as a diesel engine or a gasoline engine. Vehicles applying the present invention can be, for example, not only four-wheeled vehicles, but also all types of vehicles that travel by electric motors, such as two-wheeled straddle-type vehicles, three-wheeled vehicles (including vehicles with two front wheels and one rear wheel in addition to the front wheel and two rear wheels), and auxiliary bicycles, wherein the electric motor is driven by electricity supplied from a driving battery. Vehicle 1 can also be, for example, an electric vehicle (EV) that travels solely by an electric motor (electric motor).

[0054] 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.

[0055] Engine 10 is an internal combustion engine that operates (rotates) by burning fuel such as light oil or gasoline stored in the fuel tank (not shown) of vehicle 1 to output power. 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 may also be a rotary engine. The rotational power of engine 10 is transmitted to reduction gear 14.

[0056] 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) by 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.

[0057] The reducer 14 is, for example, a differential gear. The reducer 14 transmits the driving force of the shaft connected to the engine 10 and motor 12 to the axle connected to the drive wheel 16; that is, it transmits the rotational power of the engine 10 and motor 12. The reducer 14 may also include, for example, a transmission mechanism that combines multiple gears and shafts and transmits the rotational speed of the engine 10 and motor 12 to the axle according to a gear ratio (gear number ratio). 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.

[0058] 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 output according to the power output destination. Figure 1 In this paper, the components of PDU20 are shown as a single structure, but this is only one example. The various components of PDU20 can also be distributed in the vehicle 1.

[0059] Battery 30 is the battery used for driving vehicle 1. Battery 30 may be a rechargeable secondary battery, such as a lithium-ion battery, as its energy storage unit. Battery 30 may be a box-type battery enclosure or a fixed structure that is easy to install and remove from vehicle 1, or it may be a fixed structure that is not easy to install and remove from vehicle 1. The secondary battery included in battery 30 may be 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 combining secondary batteries and capacitors are also considered, but the structure of the secondary battery can be arbitrary. Battery 30 stores electricity (charges) received 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 from 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.

[0060] Figure 2 This is an example of the equivalent circuit of the battery 30 in vehicle 1. For example, the battery 30 has, on the positive terminal side of the energy storage unit Ba, a parallel circuit of resistor Rx and capacitor Cx, a parallel circuit of resistor Ry and capacitor Cy, a parallel circuit of resistor Rz and inductor Lz, an inductor La, and a resistor Ra connected in series. The battery 30 is an example of an "energy storage element" in the technical solution, and the inductor La connected to the energy storage unit Ba in the battery 30 is an example of an "inductive component" in the technical solution.

[0061] 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.

[0062] 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.

[0063] 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 unit connecting the first and second capacitors in parallel with the battery 30, and a series switch unit connecting the first and second capacitors in series with the battery 30. The AC generating circuit 42 generates alternating current through the resonant operation of the inductance La 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 inductance La 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.

[0064] 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 a state in which the first capacitor and the second capacitor are connected to the battery 30 in parallel by turning the parallel switch on and the series switch off, and a state in which the first capacitor and the second capacitor are connected to the battery 30 in series by turning the parallel switch off and the series switch on. During this time, the control unit 44 sets a period during which both the parallel switch and the series switch are in a non-conducting state, i.e., a so-called dead time, to switch the connection of the first capacitor and the second capacitor to the battery 30 from a parallel connection to a series connection, or from a series connection to a parallel connection.

[0065] The state in which the first capacitor and the second capacitor are connected in parallel with the storage battery 30 is an example of the "first state" in the technical solution, and the state in which the first capacitor and the second capacitor are connected in series with the storage battery 30 is an example of the "second state" in the technical solution. Details of the heating device 40 and the constituent elements of the heating device 40 will be described later.

[0066] 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. Sensors are mounted on 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.

[0067] 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 from each sensor to control device 100.

[0068] 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 on the driving control unit 70, i.e., 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 a control device such as an engine ECU (Electronic Control Unit), a motor ECU, a battery ECU, a PDU-ECU, and a VCU-ECU.

[0069] 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 starting 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 starting or stopping of the heating device 40 so that the temperature of the battery 30 rises (heats up) to a suitable temperature for use. The control device 100 can also be replaced, for example, with a control unit 44 provided with the heating device 40. That is, as the control unit 44, the control device 100 can be a structure that directly controls the parallel switch section and the series switch section of the AC generation circuit 42 provided with the heating device 40 to a conducting state or a non-conducting state, respectively.

[0070] The control device 100 operates by executing a program (software) through a hardware processor such as a CPU (Central Processing Unit). The control device 100 can also be implemented using hardware (including a circuit section) 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 such as an HDD (Hard Disk Drive) or flash memory (a storage device with non-transitory storage media) provided in the vehicle 1, or it can be stored in a removable storage medium such as a DVD or CD-ROM (a non-transitory storage medium), and installed in the HDD or flash memory provided in the vehicle 1 by assembling the storage medium into the drive unit provided in the vehicle 1.

[0071] <First Implementation>

[0072] [Structure of the AC generation circuit in the heating device]

[0073] Figure 3 This diagram illustrates 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 3 The battery 30 associated with the AC generating circuit 42-1 is also shown in the diagram. However, in Figure 3 The diagram of the inductor La of the battery 30 is omitted. The AC generation circuit 42-1 includes, for example, capacitors C1 and C2, switching elements S1, S2, and S3, diodes D1, D2, and D3. Capacitors C1 and C2 are capacitors with equal electrostatic capacitance. Switching elements S1, S2, and S3 are, for example, semiconductor switching elements such as N-channel metal oxide semiconductor field-effect transistors (MOSFETs).

[0074] Switching element S1 and diode D1 are connected in parallel to form a semiconductor switching section. In the following description, the semiconductor switching section consisting of switching element S1 and diode D1 will also be referred to as "semiconductor switching section SW1". More specifically, in semiconductor switching section SW1, on the first terminal side, the drain terminal of switching element S1 is connected to the cathode terminal of diode D1, and on the second terminal side, the source terminal of switching element S1 is connected to the anode terminal of diode D1. The gate terminal of switching element S1 is controlled (by applying a control voltage or control current) by the gate signal G1 output by control unit 44. That is, semiconductor switching section SW1 is controlled to either be on or off by the gate signal G1 output by control unit 44. In semiconductor switching section SW1, diode D1 functions as a return diode to allow the current flowing in switching element S1 to return. In the switching element S1, according to this structure, there is also a case where a parasitic diode (so-called body diode) exists. However, in the semiconductor switching section SW1, the current can be returned more efficiently by connecting the diode D1 compared to the parasitic diode.

[0075] The same applies to switching element S2 and diode D2, and switching element S3 and diode D3. In the following description, the semiconductor switching section composed of switching element S2 and diode D2 will also be referred to as "semiconductor switching section SW2", and the semiconductor switching section composed of switching element S3 and diode D3 will also be referred to as "semiconductor switching section SW3".

[0076] In AC generation 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 generation circuit 42-1, the first terminal of semiconductor switch SW2 is connected to the first terminal of capacitor C1, and the second terminal of semiconductor switch SW1 is connected to the first terminal of capacitor C2. Moreover, in AC generation circuit 42-1, the first terminal of semiconductor switch SW1 and the second terminal of semiconductor switch SW3 are connected to the second terminal of capacitor C1, and the second terminal of semiconductor switch SW2 and the first terminal of semiconductor switch SW3 are connected to the second terminal of capacitor C2.

[0077] With this structure, in the AC generation circuit 42-1, according to the control from the control unit 44, capacitors C1 and 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 gate signal G1 to the switching element S1 of the semiconductor switching unit SW1 to turn it on, outputs a gate signal G2 to the switching element S2 of the semiconductor switching unit SW2 to turn it on, and outputs a gate signal G3 to the switching element S3 of the semiconductor switching unit SW3 to turn it off, thereby connecting capacitors C1 and C2 in parallel between the positive and negative terminals of the battery 30. On the other hand, the control unit 44 outputs a gate signal G1 to the switching element S1 of the semiconductor switching unit SW1 to make it in an off state, outputs a gate signal G2 to the switching element S2 of the semiconductor switching unit SW2 to make it in an off state, and outputs a gate signal G3 to the switching element S3 of the semiconductor switching unit SW3 to make it in an on state, thereby connecting capacitor C1 and capacitor C2 in series between the positive and negative sides of the battery 30.

[0078] In AC generation circuit 42-1, capacitor C1 is an example of a "first capacitor" in the technical solution, and capacitor C2 is an example of a "second capacitor" in the technical solution. In AC generation circuit 42-1, the structure combining semiconductor switch section SW1 and semiconductor switch section SW2 is an example of a "parallel switch section" in the technical solution, and semiconductor switch section SW3 is an example of a "series switch section" in the technical solution. In each semiconductor switch section, the on-state of the switching element is an example of a "conducting state" in the technical solution, and the off-state of the switching element is an example of a "non-conducting state" in the technical solution. In AC generation circuit 42-1, the state in which capacitors C1 and C2 are connected in parallel between the positive and negative terminals of the battery 30 is an example of a "first state" in the technical solution, and the state in which capacitors C1 and C2 are connected in series between the positive and negative terminals of the battery 30 is an example of a "second state" in the technical solution.

[0079] [Operation of the heating device]

[0080] Next, the operation of generating alternating current in the alternating current generation circuit 42-1, namely the control of each semiconductor switch in the control unit 44, will be explained. Figure 4 This is a diagram illustrating an example of the operating waveform (analog waveform) of the control and AC generation circuit 42-1 of the control unit 44 in the first embodiment. Figure 5 This is a diagram illustrating an example of the path of the alternating current flowing within the alternating current generation circuit 42-1 of the first embodiment.

[0081] exist Figure 4The diagram shows the gate signals G1, G2, and G3 output by the control unit 44 to each semiconductor switch unit. Figure 4 In this diagram, a "high" level for gate signals G1, G2, and G3 represents the on state of the corresponding switching element, while a "low" level represents the off state. In the following explanation, setting the gate signal to a "high" level is referred to as "making the semiconductor switching unit conduct," and setting the gate signal to a "low" level is referred to as "making the semiconductor switching unit de-conduct." Figure 4 As shown, the control unit 44 provides a period (dead time) during which all semiconductor switches are deactivated between the period during which the semiconductor switches are turned on and the period during which the semiconductor switches are turned off.

[0082] exist Figure 4 The diagram shows an example of the voltage changes between the terminals of the battery 30 (including the inductor La) and the voltage changes between the terminals of the capacitor C1, which are controlled by the control unit 44 via gate signals G1, G2, and G3. Furthermore, in... Figure 4 The diagram shows an example of the changes in the currents flowing in the semiconductor switch section SW3, the semiconductor switch section SW1, the capacitor C1, and the battery 30 (including the inductor La) due to the control unit 44 controlling the gate signals G1, G2, and G3.

[0083] When the heating device 40 is started by the control device 100, it periodically repeats its operation. Therefore, in the following description, please refer to the relevant references. Figure 5 Come to Figure 4 The operation of the AC generating circuit 42-1 shown from time t1 will be explained.

[0084] In AC generation circuit 42-1, immediately before time t1, currents Is3 and Icap pass through... Figure 5 The path shown in (d) flows from the battery 30 in the direction of charging capacitors C1 and C2 respectively. If, during time t1 when semiconductor switches SW1 and SW2 are in a non-conducting state, the control unit 44 sets the gate signal G3 to a "high" level, thus turning on semiconductor switch SW3, then capacitors C1 and C2 are connected in series with the battery 30. Therefore, in the AC generation circuit 42-1, currents Is3 and Icap flow through... Figure 5The path shown in (a) flows from the battery 30 in the direction of charging capacitors C1 and C2 respectively. Consequently, in the AC generating circuit 42-1, the voltage Vcap increases, and the current Ibatt decreases towards 0A.

[0085] Then, when the voltage Vcap reaches its positive peak voltage at time t2, the direction of the current Ibatt reverses. At this time, semiconductor switches SW1 and SW2 remain in a non-conducting state. Therefore, in the AC generation circuit 42-1, capacitors C1 and C2 switch to discharging, and currents Is3 and Icap flow through... Figure 5 The path shown in (b) flows in the direction of charging the battery 30. Therefore, in the AC generating circuit 42-1, the current Ibatt continues to increase in the direction of charging the battery 30, while the voltage Vcap changes to a decreasing direction.

[0086] Subsequently, at time t3, the control unit 44 first sets the gate signal G3 to a "low" level to make the semiconductor switch SW3 non-conducting. As a result, in the AC generation circuit 42-1, the path of current Is3 is cut off, and current Is3 becomes 0A.

[0087] Subsequently, the control unit 44 sets gate signals G1 and G2 to a "high" level to turn on semiconductor switches SW1 and SW2. As a result, in the AC generation circuit 42-1, capacitors C1 and C2 are connected in parallel with the battery 30. Therefore, in the AC generation circuit 42-1, the current (current Is1) that charges the battery 30 by discharging capacitors C1 and C2 respectively passes through... Figure 5 The current flows along the path shown in (c). Then, in the AC generating circuit 42-1, the current Ibatt changes to a decreasing direction, and the voltage Vcap continues to decrease.

[0088] Then, when the current Ibatt becomes 0A at time t4, the direction of the current Ibatt reverses. At this time, semiconductor switching sections SW1 and SW2 are still in the on state. Therefore, in the AC generation circuit 42-1, the current (current Icap) passes through... Figure 5 The path shown in (d) flows from the battery 30 in the direction of charging capacitors C1 and C2 respectively. Therefore, in the AC generating circuit 42-1, the current Ibatt continues to increase in the direction of discharging the battery 30, and the voltage Vcap continues to rise.

[0089] Subsequently, at time t5, control unit 44 first sets gate signal G1 and gate signal G2 to a "low" level to de-conduct semiconductor switch units SW1 and SW2. Therefore, in AC generation circuit 42-1, the path of current Icap becomes the path through diode D1 in semiconductor switch unit SW1 (return path), and the path of current from capacitor C2 becomes the path through diode D2 in semiconductor switch unit SW2 (return path), but... Figure 5 Similarly, as shown in (d), the current (current Icap) continues to flow from the battery 30 in the direction of charging capacitors C1 and C2 respectively.

[0090] Then, the control unit 44 sets the gate signal G3 to a "high" level to turn on the semiconductor switch SW3. The operation of the AC generating circuit 42-1 in this case is the same as the operation at time t1 described above. Subsequently, the AC generating circuit 42-1 and the control unit 44 periodically repeat the above operations.

[0091] Thus, in the heating device 40, the control unit 44 controls the on / off state of each semiconductor switch, switching the connection of capacitors C1 and C2 to the battery 30 to a series connection or a parallel connection. This generates a current Ibatt (alternating current) flowing to the battery 30 through the resonant action of the inductance La of the battery 30 and at least capacitor C1. Consequently, the battery 30 heats up under the influence of the current Ibatt.

[0092] At this time, the timing of the control unit 44 controlling the semiconductor switching unit, that is, the timing of switching the connection between capacitor C1 and capacitor C2, is as follows: Figure 4 As explained at times t3 and t5, after the semiconductor switch that was in the conducting state is first turned off, the other semiconductor switches that were in the off state are turned on. In other words, after the control unit 44 temporarily returns the current flowing in the switching element of each semiconductor switch to the diode, it controls each semiconductor switch to switch the connection between capacitor C1 and capacitor C2.

[0093] Here, regarding the timing of the control unit 44 controlling the semiconductor switching unit (e.g.) Figure 4The timing determination (for times t3 and t5) shown can be made by the control unit 44 through measuring (monitoring) the components of the AC generating circuit 42-1 and the current and voltage values ​​of the battery 30, or based on the operating state of the AC generating circuit 42-1. For example, when determining timing by monitoring the current and voltage values, the control unit 44 monitors the current (current Icap) and voltage (voltage Vcap) values ​​of capacitor C1, capacitor C2, battery 30 (current Ibatt), the voltage values ​​on the positive and negative terminals (voltage Vbatt), and the current (current Is1, current Is3) and voltage values ​​at the terminals of any one or more semiconductor switches (e.g., semiconductor switches in the on state). In this case, a current sensor for detecting current and a voltage sensor for detecting voltage are provided in the AC generating circuit 42-1 at the location where the control unit 44 monitors the current and voltage values. Therefore, the control unit 44 can determine the timing... Figure 4 The timing of the control semiconductor switch unit is shown in cases such as time t3 and time t5. For example, when the timing is determined based on the operating state of the AC generation circuit 42-1, the control unit 44 determines the timing of the control semiconductor switch unit based on a predetermined timing based on the AC current. The predetermined timing based on the AC current is, for example, the timing when the AC current decreases to 0A, the timing when it increases to 0A, or the timing at which the AC current can be determined based on the period or duty cycle of the AC current (e.g., before the predetermined time). Thus, the control unit 44 can determine the timing based on the characteristics of the AC current generated and applied (flowing to) the battery 30. Figure 4 The timing of the control semiconductor switch is shown at times t3 and t5.

[0094] Thus, in the heating device 40 of the first embodiment, the AC generating circuit 42-1 generates an AC current based on the power stored in the battery 30 by resonantly exchanging the magnetic energy stored in the inductor La of the battery 30 and the electrostatic energy stored in at least the capacitor C1, thereby heating the battery 30 more efficiently.

[0095] However, in the AC generating circuit 42-1, since each semiconductor switching section has a diode for return current, it is possible for the current to flow in an unintended path depending on factors such as the magnitude, period, and duty cycle of the generated AC current. For example, if the frequency of the AC current generated by the AC generating circuit 42-1 is higher than the resonant frequency, the amplitude of the AC current becomes narrower, and therefore, the amplitude of the voltage between the terminals of capacitors C1 and C2 also becomes narrower. In this case, in the AC generating circuit 42-1, such as Figure 4As shown, the voltage (e.g., voltage Vcap) across capacitors C1 and C2 is always a positive value. However, when the frequency of the AC current generated by the AC generating circuit 42-1 approaches the resonant frequency, the amplitude of the AC current widens, and the amplitude of the voltage between the terminals of capacitors C1 and C2 also widens. In this case, in the AC generating circuit 42-1, for example... Figure 4 During the period from time t2 to time t3, when the battery 30 is charged by connecting capacitor C1 and capacitor C2 in series, the voltages (e.g., voltage Vcap) of capacitors C1 and C2 sometimes become negative. Therefore, in the AC generation circuit 42-1, the voltage through capacitors C1 and C2 becomes negative, causing the voltage of the switching element in the semiconductor switching section to be reverse-biased, forming a current path that does not pass through either capacitor C1 or C2 (an unintended path). In this case, in the AC generation circuit 42-1, during resonant operation, the energy exchanged between inductor La and capacitor C1 decreases, and the amplitude of the AC current narrows. Consequently, the efficiency of heating the battery 30 in the AC generation circuit 42-1 decreases.

[0096] Here, in the AC generating circuit 42-1, an example of the case where current flows in an unintended path is explained. Figure 6 This is another example of the operating waveform (analog waveform) of the control and AC generation circuit 42-1 of the control unit 44 in the first embodiment. Figure 7 This is a diagram illustrating another example of the path of the alternating current flowing within the alternating current generation circuit 42-1 of the first embodiment. Figure 6 The diagram illustrates an example where, in an AC generating circuit 42-1, capacitors C1 and C2 are connected in series to charge the capacitors, causing the current to flow in an unintended path, thus narrowing the amplitude of the AC current. In the following description, the operation when the current flows in an unintended path is considered, referring to... Figure 7 The operation of AC generating circuit 42-1 is explained.

[0097] In the AC generating circuit 42-1, during the period P1 when capacitors C1 and C2 are connected in series with the battery 30, capacitors C1 and C2 discharge respectively, and currents Is3 and Icap are in the same state. Figure 5 In the same path shown in (b), the voltage Vcap decreases and the current Ibatt increases.

[0098] Subsequently, when the voltage Vcap changes from 0V to the negative region, currents Is3 and Icap flow from battery 30 in the direction of charging capacitors C1 and C2. At this time, the current should have flowed from... Figure 5The path shown in (b) flows along the same path without change, but the current is made continuous by the inductance La of the battery 30, thereby forming Figure 7 The diagram shows an unintended current path. More specifically, the current flows in the order of semiconductor switch SW1, semiconductor switch SW3, and semiconductor switch SW2, forming a path that bypasses capacitors C1 and C2. Consequently, in the AC generation circuit 42-1, during period P2, semiconductor switches SW1 and SW3 are in a non-conducting state, thus increasing the current Is1, which should not normally flow (0A). Figure 7 As shown, the current Icap used to charge capacitors C1 and C2 decreases. That is, the electrostatic energy exchanged with the inductance La of the battery 30 for resonant operation decreases. As a result, in the AC generating circuit 42-1, the decrease in voltage Vcap stalls, the current Ibatt does not increase sufficiently but flows in a decreasing direction, and the amplitude of the AC current narrows.

[0099] Subsequently, the control unit 44 connects capacitors C1 and C2 in parallel with the battery 30, but during period P2, the current path does not flow from... Figure 7 The path shown has changed.

[0100] Then, when the current Ibatt becomes 0A, the direction of the current Ibatt reverses. Since capacitors C1 and C2 are connected in parallel with battery 30, during period P3, the current flows in the same direction as... Figure 5 The current flows to capacitors C1 and C2 respectively in the same path shown in (d). As a result, in the AC generating circuit 42-1, the amount of charge to capacitors C1 and C2 increases, and the voltage Vcap begins to rise.

[0101] Subsequently, when the control unit 44 sets the gate signal G1 and gate signal G2 to a "low" level, causing the semiconductor switch units SW1 and SW2 to become non-conducting, during period P4, the current is in the same state as... Figure 5 The current flows in the same path as shown in (a). Then, the control unit 44 sets the gate signal G3 to a "high" level, turning on the semiconductor switch SW3. At this time, the current path in the AC generation circuit 42-1 remains unchanged, but then the direction of the current Ibatt reverses, and the current path returns to the same path as during period P1. Figure 5 (The path shown in (b)). Then, the same actions are repeated periodically.

[0102] Thus, in the heating device 40 of the first embodiment, a current Ibatt (alternating current) flowing to the battery 30 is generated by the resonant operation of the inductor La and at least the capacitor C1 of the battery 30. However, in the heating device 40 of the first embodiment, for example, if the current flows in an unintended path depending on the magnitude, period, duty cycle, and other conditions of the generated alternating current, the amplitude of the generated alternating current becomes narrower, which may reduce the heating efficiency of the battery 30.

[0103] <Second Implementation>

[0104] [Structure of the AC generation circuit in the heating device]

[0105] Figure 8 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 8 Also shown is the battery 30 associated with the AC generating circuit 42-2 (the inductor La is omitted from the illustration). The AC generating circuit 42-2 is a structure that avoids forming unintended paths as envisioned in the AC generating circuit 42-1 of the first embodiment. The AC generating circuit 42-2 includes, for example, capacitors C1 and C2, switching elements S1a, S1b, S2a, S2b, and S3, diodes D1a, D1b, D2a, D2b, and D3.

[0106] In the AC generation circuit 42-2, a first semiconductor switch section consisting of a switching element S1a and a diode D1a, and a second semiconductor switch section consisting of a switching element S1b and a diode D1b, are connected in series in such a reverse-biased manner to form a bidirectional semiconductor switch section. In the following description, this semiconductor switch section is also referred to as the "bidirectional semiconductor switch section SW1-2". The gate terminals of the switching elements S1a and S1b are controlled to be either on or off by the gate signal G1 output by the control unit 44. In the bidirectional semiconductor switch section SW1-2, diodes D1a and D1b function as return diodes that allow current to flow back in opposite directions.

[0107] The semiconductor switching section, consisting of switching element S2a, switching element S2b, diode D2a, and diode D2b, is the same as the bidirectional semiconductor switching section SW1-2. In the following description, the semiconductor switching section with this structure will also be referred to as "bidirectional semiconductor switching section SW2-2".

[0108] The connections of capacitors C1 and C2, bidirectional semiconductor switch SW1-2, bidirectional semiconductor switch SW2-2, and semiconductor switch SW3 in AC generation circuit 42-2 are equivalent to those in AC generation circuit 42-1 of the first embodiment.

[0109] With this structure, in AC generation circuit 42-2, similar to AC generation circuit 42-1, capacitors C1 and C2 are connected in parallel or in series between the positive and negative terminals of battery 30 according to the control from control unit 44.

[0110] In the AC generating circuit 42-2, the structure that combines the bidirectional semiconductor switch section SW1-2 and the bidirectional semiconductor switch section SW2-2 is an example of the "parallel switch section" in the technical solution, and the semiconductor switch section SW3 is an example of the "series switch section" in the technical solution.

[0111] [Operation of the heating device]

[0112] Next, the operation of generating alternating current in the alternating current generating circuit 42-2 will be explained. Figure 9 This is a diagram illustrating an example of the operating waveform (analog waveform) of the control and AC generation circuit 42-2 of the control unit 44 in the second embodiment. Figure 10 This is a diagram illustrating an example of the path of the alternating current flowing within the alternating current generation circuit 42-2 in the second embodiment. Reference will be made appropriately in the following description. Figure 10 right Figure 9 The operation of the AC generating circuit 42-2 shown will be explained.

[0113] The control unit 44 controls each semiconductor switch section in the same way as the AC generation circuit 42-1 for the AC generation circuit 42-2. More specifically, after the control unit 44 first turns the semiconductor switch section that is in the on state to the off state, it turns the other semiconductor switch sections that are in the off state to the on state. This causes the current flowing in the switching element of each semiconductor switch section to temporarily flow back to the diode. Then, it controls each semiconductor switch section to switch capacitor C1 and capacitor C2 to be connected in series or in parallel.

[0114] In the AC generating circuit 42-2, during the period when capacitors C1 and C2 are connected in series with the battery 30, P1, capacitors C1 and C2 discharge respectively, and currents Is3 and Icap pass through... Figure 10 The path shown in (a) flows in the direction of charging the battery 30. Consequently, in the AC generating circuit 42-2, the voltage Vcap decreases, and the current Ibatt, after reaching its peak voltage in the direction of charging the battery 30, reverses and decreases towards 0A.

[0115] Subsequently, the voltage Vcap changes from 0V to a negative region. However, in the AC generation circuit 42-2, since the bidirectional semiconductor switch SW1-2 and bidirectional semiconductor switch SW2-2 are in a non-conducting state, even though the inductance La of the battery 30 makes the current continuous, it is not possible to form a current. Figure 7 The unintended current path is shown. More specifically, the bidirectional semiconductor switch SW1-2 and the bidirectional semiconductor switch SW2-2 (more specifically, the second semiconductor switch) do not cause... Figure 7 As shown, the current Ibatt from battery 30 passes through, and the current path does not lead from... Figure 10 The path shown in (a) changes. Therefore, in the AC generating circuit 42-2, the current Is1 does not change from 0A, the voltage Vcap continues to decrease, the electrostatic energy exchanged between the current and the inductance La of the battery 30 for resonant operation does not decrease, and the voltage Vcap decreases sufficiently. That is, in the AC generating circuit 42-2, a wider amplitude of the AC current can be ensured.

[0116] Then, when the current Ibatt becomes 0A, the direction of the current Ibatt reverses. At this time, in the AC generation circuit 42-2, the bidirectional semiconductor switch SW1-2 and the bidirectional semiconductor switch SW2-2 are still in a non-conducting state. Therefore, during period P2, the currents Is3 and Icap pass through... Figure 10 The path shown in (b) flows from battery 30 in the direction of charging capacitors C1 and C2. Consequently, in AC generating circuit 42-2, current Ibatt continues to increase in the direction of discharging battery 30, and voltage Vcap begins to rise.

[0117] Subsequently, the control unit 44 connects capacitors C1 and C2 in parallel with the battery 30, thereby in the AC generation circuit 42-2, during period P3, the current Ibatt from the battery 30 flows through... Figure 10 The current flows through the path shown in (c) to capacitors C1 and C2 respectively. Then, in the AC generating circuit 42-2, capacitors C1 and C2 continue to be charged, and the voltage Vcap continues to rise.

[0118] exist Figure 9 During the initial phase of P3, current Is3 temporarily generates a positive current, but this is caused by the reverse recovery operation of semiconductor switch SW3 and is set within a short time.

[0119] Then, when the voltage Vcap becomes a positive peak voltage, the direction of the current (current Icap) in capacitors C1 and C2 reverses. At this time, the bidirectional semiconductor switch SW1-2 and bidirectional semiconductor switch SW2-2 are still in the conducting state. Therefore, in the AC generation circuit 42-2, during period P4, the current (current Icap) flows through... Figure 10 The path shown in (d) flows from capacitors C1 and C2 in the direction of charging battery 30, respectively. Therefore, in AC generating circuit 42-2, current Ibatt continues to increase in the direction of charging battery 30, while voltage Vcap changes to a decreasing direction.

[0120] Then, the control unit 44 connects capacitors C1 and C2 in series with the battery 30, thereby returning the current path in the AC generation circuit 42-2 to the same path as during period P1. Figure 10 (The path shown in (a)). Then, the same actions are repeated periodically.

[0121] Thus, in the heating device 40 of the second embodiment, the semiconductor switch SW1 and semiconductor switch SW2 of the AC generation circuit 42-1 of the first embodiment are replaced by bidirectional semiconductor switch SW1-2 and bidirectional semiconductor switch SW2-2, respectively. These bidirectional semiconductor switch SW1-2 and bidirectional semiconductor switch SW2-2 are composed of two semiconductor switch units connected in series with diodes in opposite directions. Therefore, in the heating device 40 of the second embodiment, when capacitors C1 and C2 are connected in series to charge each capacitor, even if the inductance La of the battery 30 causes the current to be continuous and the voltage of the switching element of the non-conducting semiconductor switch unit is reverse-biased, the bidirectional semiconductor switch SW1-2 and bidirectional semiconductor switch SW2-2 remain in a non-conducting state. Therefore, in the heating device 40 of the second embodiment, in the AC generation circuit 42-2, an unintended current path (see reference 42-1) can be avoided. Figure 7 The heating device 40 of the second embodiment operates smoothly. Therefore, in the heating device 40 of the second embodiment, the resonant operation of the AC generating circuit 42-2 and the inductance La of the battery 30 can be maintained, thereby generating an AC current with a sufficient amplitude (wider than the amplitude of the AC generating circuit 42-1). Therefore, in the heating device 40 of the second embodiment, the battery 30 can be heated more efficiently by the generated AC current.

[0122] <Third Implementation Method>

[0123] [Structure of the AC generation circuit in the heating device]

[0124] Figure 11 This diagram illustrates an example of the structure of the AC generation circuit 42 (hereinafter referred to as "AC generation circuit 42-3") included in the heating device 40 of the third embodiment. Figure 11 Also shown is the battery 30 associated with the AC generating circuit 42-3 (the inductor La is omitted from the illustration). The AC generating circuit 42-3, like the AC generating circuit 42-2 of the second embodiment, is structured to avoid forming unintended paths as envisioned in the AC generating circuit 42-1 of the first embodiment. The AC generating circuit 42-3 includes, for example, capacitors C1 and C2, switching elements S1, S2, S3a, S3b, diodes D1, D2, D3a, and D3b.

[0125] The AC generation circuit 42-3 is a structure in which the semiconductor switch SW3 of the AC generation circuit 42-1 is configured to be the same bidirectional semiconductor switch SW1-2 and bidirectional semiconductor switch SW2-2 as the bidirectional semiconductor switch SW1-2 of the AC generation circuit 42-2 (hereinafter referred to as "bidirectional semiconductor switch SW3-2"). In the AC generation circuit 42-3, the bidirectional semiconductor switch SW1-2 and bidirectional semiconductor switch SW2-2 of the AC generation circuit 42-2 are not bidirectional semiconductor switches, but remain unidirectional semiconductor switches. The gate terminals of the switching elements S3a and S3b constituting the bidirectional semiconductor switch SW3-2 are controlled to be either turned on or off by the gate signal G3 output by the control unit 44. In the bidirectional semiconductor switch SW3-2, diodes D3a and D3b also function as return diodes that allow current to flow back in opposite directions.

[0126] The connections of capacitors C1 and C2, semiconductor switch SW1, semiconductor switch SW2, and bidirectional semiconductor switch SW3-2 in AC generation circuit 42-3 are equivalent to those in AC generation circuit 42-1 of the first embodiment.

[0127] With this structure, in AC generation circuit 42-3, similar to AC generation circuit 42-1 and AC generation circuit 42-2, capacitor C1 and capacitor C2 are connected in parallel or in series between the positive and negative terminals of battery 30 according to the control from control unit 44.

[0128] In the AC generation circuit 42-3, the structure that combines the semiconductor switch section SW1 and the semiconductor switch section SW2 is an example of the "parallel switch section" in the technical solution, and the bidirectional semiconductor switch section SW3-2 is an example of the "series switch section" in the technical solution.

[0129] [Operation of the heating device]

[0130] Next, the operation of generating alternating current in the alternating current generating circuit 42-3 will be explained. Figure 12 This is a diagram illustrating an example of the operating waveform (analog waveform) of the control and AC generation circuit 42-3 of the control unit 44 in the third embodiment. Figure 13 This is a diagram illustrating an example of the path of the alternating current flowing within the alternating current generation circuit 42-3 of the third embodiment. Reference will be made appropriately in the following description. Figure 13 right Figure 12 The operation of the AC generating circuit 42-3 shown will be explained.

[0131] The control unit 44, similar to the AC generating circuits 42-1 and 42-2, first turns the semiconductor switch in the conducting state into the non-conducting state to temporarily reverse the flow of current, and then turns the other non-conducting semiconductor switches into the conducting state to switch the connection between capacitor C1 and capacitor C2 to a series connection or a parallel connection.

[0132] In the AC generating circuit 42-3, during the period when capacitors C1 and C2 are connected in series with the battery 30, currents Is1 and Icap pass through P1. Figure 13 The path shown in (a) flows from the battery 30 toward the direction of charging capacitors C1 and C2, with voltage Vcap rising and current Ibatt decreasing toward 0A.

[0133] Then, when the voltage Vcap becomes the positive peak voltage, the current Ibatt reverses, and during this period, the current (current Icap) flows through P2. Figure 13 The path shown in (b) flows from capacitors C1 and C2 in the direction of charging the battery 30, respectively. The current Ibatt continues to increase in the direction of charging the battery 30, while the voltage Vcap changes to a decreasing direction.

[0134] Then, the control unit 44 connects capacitors C1 and C2 in parallel with the battery 30, thereby in the AC generation circuit 42-3, during period P3, the current Ibatt from the battery 30 flows through... Figure 13 The current flows through the path shown in (c) to capacitors C1 and C2 respectively, and the voltage Vcap becomes a negative voltage value. At this time, in the AC generating circuit 42-3, the bidirectional semiconductor switch SW3-2 is in a non-conducting state, therefore, it is possible to avoid forming Figure 7The circuit operates without the current path (not the intended path) passing through either capacitor C1 or capacitor C2. More specifically, when the voltage Vcap becomes negative from 0V, in the AC generating circuit 42-3, the potential of the second terminal side (the source terminal of the switching element S2) of the semiconductor switch SW2 is lower than the potential of the first terminal side (the drain terminal of the switching element S1) of the semiconductor switch SW1. However, even in this case, in the AC generating circuit 42-3, the bidirectional semiconductor switch SW3-2 (more specifically, the second semiconductor switch) does not allow the current Icap to pass through the semiconductor switch SW1 side; the current path does not pass through the semiconductor switch SW1 side. Figure 13 The path shown in (c) changes. As a result, in the AC generating circuit 42-3, the current Is3 will not change from 0A, the voltage Vcap will continue to decrease, the electrostatic energy exchanged between the battery 30 and the inductance La in order to perform the resonant operation will not decrease, the current Ibatt will continue to decrease toward 0A, and the voltage Vcap will continue to decrease.

[0135] Then, when the voltage Vcap becomes a negative peak voltage, the directions of the currents (current Icap) in capacitors C1 and C2 reverse. At this time, the bidirectional semiconductor switch SW3-2 is still in a non-conducting state. Therefore, in the AC generation circuit 42-3, during period P4, currents Is1 and Icap flow through... Figure 13 The path shown in (d) flows from the battery 30 in the direction of charging capacitors C1 and C2. The current Ibatt continues to increase in the direction of discharging the battery 30, and the voltage Vcap begins to rise.

[0136] Then, the control unit 44 connects capacitors C1 and C2 in series with the battery 30, thereby returning the current path in the AC generation circuit 42-3 to the same path as during period P1. Figure 13 (The path shown in (a)). Then, the same actions are repeated periodically.

[0137] Thus, in the heating device 40 of the third embodiment, the AC generating circuit 42-3 replaces the semiconductor switch SW3 of the AC generating circuit 42-1 of the first embodiment with a bidirectional semiconductor switch SW3-2. Therefore, in the heating device 40 of the third embodiment, when capacitors C1 and C2 are connected in parallel and charged, even if the voltage Vcap changes from 0V to a negative region, the bidirectional semiconductor switch SW3-2 remains in a non-conducting state. That is, in the heating device 40 of the third embodiment, even if the potentials of semiconductor switches SW1 and SW2 become unbalanced due to the voltage Vcap changing from 0V to a negative region, the bidirectional semiconductor switch SW3-2 remains in a non-conducting state. Therefore, in the heating device 40 of the third embodiment, in the AC generating circuit 42-3, unintended current paths as in the AC generating circuit 42-1 are not formed (see [reference]). Figure 7 The device operates in a manner that maintains resonance with the inductance La of the battery 30, generating an alternating current with a sufficient amplitude (wider than the amplitude of the alternating current generation circuit 42-1). Therefore, even in the heating device 40 of the third embodiment, the generated alternating current can more efficiently heat the battery 30.

[0138] Here, the differences in the characteristics of the alternating current generated by the AC generating circuit 42-1 of the first embodiment, the AC generating circuit 42-2 of the second embodiment, and the AC generating circuit 42-3 of the third embodiment will be explained. Figure 14 This is a graph comparing the amplitude characteristics of the alternating current generated by alternating current generating circuits 42 (AC generating circuits 42-1, 42-2, and 42-3). Figure 14 The diagram shows the characteristics of the effective value (rms value) of the current value representing the amplitude of the AC current generated by each AC generating circuit 42 when the duty cycle is set to the same and the frequency is varied. For example... Figure 14 As shown, in the AC generation circuit 42-1, the value of the generated AC current in frequency band FB1 remains unchanged. This is because in the AC generation circuit 42-1, when the voltage Vcap changes from 0V to negative, a current is formed... Figure 7 The unintended current path shown leads to a reduction in the energy exchanged between inductor La and capacitor C1 during resonant operation. Conversely, in AC generation circuits 42-2 and 42-3, the generated AC current values ​​change across the entire frequency band. Although the frequency bands differ in AC generation circuits 42-2 and 42-3, the effective value is higher compared to AC generation circuit 42-1. Therefore, it can be concluded that in AC generation circuits 42-2 and 42-3, it is possible to avoid forming... Figure 7The unintended current path shown can be used to operate without causing a reduction in the energy exchanged between the inductor La and the capacitor C1 during resonant operation.

[0139] <Fourth Implementation>

[0140] [Structure of the AC generation circuit in the heating device]

[0141] In the AC generating circuit 42-2 of the second embodiment, the semiconductor switch SW1 and semiconductor switch SW2 provided in the AC generating circuit 42-1 are replaced with bidirectional semiconductor switches. In the AC generating circuit 42-3 of the third embodiment, the semiconductor switch SW3 provided in the AC generating circuit 42-1 is replaced with a bidirectional semiconductor switch. However, the semiconductor switch replaced by a bidirectional semiconductor switch in the AC generating circuit 42 may not be any one of semiconductor switch SW1, semiconductor switch SW2, or semiconductor switch SW3; that is, it may not be either a parallel switch or a series switch. Both the parallel switch and the series switch may be replaced by a bidirectional semiconductor switch.

[0142] Figure 15 This diagram illustrates an example of the structure of the AC generation circuit 42 (hereinafter referred to as "AC generation circuit 42-4") included in the heating device 40 of the fourth embodiment. Figure 15 The battery 30 associated with the AC generating circuit 42-4 is also shown (the inductor La is omitted from the illustration). The AC generating circuit 42-4, like the AC generating circuit 42-2 of the second embodiment and the AC generating circuit 42-3 of the third embodiment, is structured to avoid forming unintended paths as envisioned in the AC generating circuit 42-1 of the first embodiment. The AC generating circuit 42-4 includes, for example, capacitors C1 and C2, switching elements S1a, S1b, S2a, S2b, S3a, S3b, diodes D1a, D1b, D2a, D2b, D3a, and D3b.

[0143] The AC generating circuit 42-4 is a structure in which all the semiconductor switching units of the AC generating circuit 42-1 are replaced by bidirectional semiconductor switching units of the AC generating circuits 42-2 and 42-3. The connections of capacitors C1 and C2, bidirectional semiconductor switching units SW1-2, SW2-2, and SW3-2 in the AC generating circuit 42-4 are equivalent to those in the AC generating circuit 42-1 of the first embodiment.

[0144] With this structure, in the AC generation circuit 42-4, similar to the AC generation circuit 42 in the first to third embodiments, capacitor C1 and capacitor C2 are connected in parallel or in series between the positive and negative sides of the battery 30 according to the control from the control unit 44.

[0145] In the AC generating circuit 42-4, the structure of combining the bidirectional semiconductor switch section SW1-2 and the bidirectional semiconductor switch section SW2-2 is an example of the "parallel switch section" in the technical solution, and the bidirectional semiconductor switch section SW3-2 is an example of the "series switch section" in the technical solution.

[0146] [Operation of the heating device]

[0147] Next, the operation of generating alternating current in the alternating current generating circuit 42-4 will be explained. Figure 16 This is a diagram illustrating an example of the operating waveform (analog waveform) of the control and AC generation circuit 42-4 of the control unit 44 in the fourth embodiment. Figure 17 This is a diagram illustrating an example of the path of the alternating current flowing within the alternating current generation circuit 42-4 of the fourth embodiment. Reference will be made appropriately in the following description. Figure 17 right Figure 16 The operation of the AC generating circuit 42-4 shown will be explained.

[0148] Similar to the AC generating circuits 42 in the first to third embodiments, the control unit 44, after temporarily reversing the flow of current by turning off the conducting bidirectional semiconductor switches of the AC generating circuit 42-4, turns on the other bidirectional semiconductor switches, switching the connection between capacitors C1 and C2 to either a series or parallel connection. At this time, when the AC current generated by the AC generating circuit 42-4 is approximately 0A, the control unit 44 turns on the bidirectional semiconductor switches that were previously in a non-conducting state. In other words, the control unit 44 can perform ZCS (Zero Current Switching) control on the AC generating circuit 42-4.

[0149] When the current Ibatt reaches approximately 0A at time t1, the control unit 44 turns on the bidirectional semiconductor switch SW3-2, thereby connecting capacitors C1 and C2 in series with the battery 30. Consequently, in the AC generation circuit 42-4, also during period P1, capacitors C1 and C2 discharge respectively, and currents Is3 and Icap flow through... Figure 17 The path shown in (a) flows in the direction of charging the battery 30. Consequently, in the AC generating circuit 42-4, the voltage Vcap decreases, and the current Ibatt increases in the direction of charging the battery 30.

[0150] Subsequently, at time t2, the voltage Vcap changes from 0V to a negative region. However, since the bidirectional semiconductor switch SW1-2 and bidirectional semiconductor switch SW2-2 in the AC generation circuit 42-4 are in a non-conducting state, no voltage is formed. Figure 7 The unintended path of current operation is shown, such as Figure 17 As shown in (b), the current path does not start from... Figure 17 The path shown in (a) changes. Therefore, in the AC generating circuit 42-4, also during period P2, the current Is1 does not change from 0A, and the voltage Vcap continues to decrease. Thus, in the AC generating circuit 42-4, the current Ibatt flows in a manner that sufficiently increases and then decreases in the direction of charging the battery 30, ensuring a wider amplitude of the AC current.

[0151] Subsequently, when the current Ibatt reaches approximately 0A, the control unit 44 deactivates the bidirectional semiconductor switch SW3-2, and then activates both bidirectional semiconductor switches SW1-2 and SW2-2 at time t3, thereby connecting capacitors C1 and C2 in parallel with the battery 30. Thus, in the AC generating circuit 42-4, also during period P3, currents Is1 and Icap flow through... Figure 17 The path shown in (c) flows from the battery 30 in the direction of charging capacitors C1 and C2. The current Ibatt continues to increase in the direction of discharging the battery 30, and the voltage Vcap begins to rise.

[0152] Subsequently, at time t4, the voltage Vcap changes from 0V to a positive region, and the voltage Vcap rises further. However, since the bidirectional semiconductor switch SW3-2 in the AC generation circuit 42-4 is in a non-conducting state, it is possible to prevent the formation of [a specific circuit / function]. Figure 7 The unintended path of the current is shown, as... Figure 17 As shown in (d), the current path does not start from... Figure 17 The path shown in (c) changes. Therefore, in the AC generation circuit 42-4, also during period P4, the current Is3 does not change from 0A, and the voltage Vcap continues to rise. Thus, in the AC generation circuit 42-4, the current Ibatt flows in a manner that sufficiently increases and then decreases in the direction of discharging the battery 30, ensuring a wider amplitude of the AC current.

[0153] Subsequently, when the current Ibatt reaches approximately 0A at time t5, the control unit 44 connects capacitors C1 and C2 in series with the battery 30. This causes the current path in the AC generation circuit 42-4 to return to the same path as during period P1. Figure 17 (The path shown in (a)). Then, the same actions are repeated periodically.

[0154] Thus, in the heating device 40 of the fourth embodiment, all the semiconductor switching units included in the AC generation circuit 42-1 of the first embodiment are replaced by the AC generation circuit 42-4 with bidirectional semiconductor switching units. Therefore, in the heating device 40 of the fourth embodiment, when the bidirectional semiconductor switching units SW1-2 and SW2-2 are in a non-conducting state (when charging the battery 30 by connecting capacitor C1 and capacitor C2 in series), even if the voltage Vcap changes from 0V to a negative region, the bidirectional semiconductor switching units SW1-2 and SW2-2 remain in a non-conducting state. Furthermore, in the heating device 40 of the fourth embodiment, when the bidirectional semiconductor switching unit SW3-2 is in a non-conducting state (when charging each capacitor by connecting capacitor C1 and capacitor C2 in parallel), even if the voltage Vcap changes from 0V to a positive region, the bidirectional semiconductor switching unit SW3-2 remains in a non-conducting state. That is, in the heating device 40 of the fourth embodiment, in the AC generating circuit 42-4, current does not flow to the bidirectional semiconductor switch section which is in a non-conducting state; in other words, current only flows to the bidirectional semiconductor switch section which is in a conducting state. Therefore, in the heating device 40 of the fourth embodiment, in the AC generating circuit 42-4, an unintended current path such as that of the AC generating circuit 42-1 can be avoided (see [reference]). Figure 7 The device operates smoothly and maintains resonance with the inductance La of the battery 30, thereby generating an alternating current with a sufficient amplitude (wider than the amplitude of the alternating current generation circuit 42-1). Therefore, in the heating device 40 of the fourth embodiment, the generated alternating current can also more efficiently heat the battery 30.

[0155] Here, the differences in the characteristics of the alternating current generated by the AC generating circuit 42 in the first to third embodiments and the AC generating circuit 42-4 in the fourth embodiment will be explained. Figure 18 This is a graph comparing the characteristics of the amplitude of the alternating current generated by the alternating current generating circuit 42 (alternating current generating circuit 42-1, alternating current generating circuit 42-2, alternating current generating circuit 42-3 and alternating current generating circuit 42-4). Figure 18 also with Figure 14 Similarly, the characteristics of the effective value (rms value) of the current value representing the amplitude of the AC current generated by each AC generating circuit 42 are shown when the duty cycle is set to the same and the frequency is varied. Figure 18 In the middle, the characteristics of the amplitude of the alternating current generated by the alternating current generating circuit 42-4 in the fourth embodiment are compared with... Figure 14The characteristics of the amplitude of the alternating current generated by the alternating current generating circuit 42 of the first to third embodiments shown are illustrated in an overlapping manner. Figure 18 As shown, in the AC generating circuit 42-4, compared with the AC generating circuit 42 of the first to third embodiments, the effective value of the generated AC current varies more (with a wider amplitude variation). Therefore, it can be seen that the AC generating circuit 42-4 of the fourth embodiment can generate an AC current with a higher heating effect compared with the AC generating circuit 42 of the first to third embodiments.

[0156] However, in use Figure 16 and Figure 17 In the operation of the AC generating circuit 42-4, ZCS control is performed to turn on the bidirectional semiconductor switch when the AC current generated by the AC generating circuit 42-4 is approximately 0A. Furthermore, as described above, the control unit 44 turns on the bidirectional semiconductor switch after first turning it off to temporarily reverse the current flow. Therefore, ZCS control is not suitable for adjusting the amount of AC current generated by the AC generating circuit 42-4, for example. For example, when the bidirectional semiconductor switch is turned off at the timing when the AC current generated by the AC generating circuit 42-4 separates from approximately 0A, the inductor La of the battery 30 is cut off midway through the current flow. As a result, a surge voltage Vbatt is generated in the AC generating circuit 42-4, placing a load such as heat on the switching element of the bidirectional semiconductor switch. In this case, the loss of the generated AC current increases.

[0157] Here, an example of a surge voltage generation scenario is explained in AC generation circuit 42-4. Figure 19 This is another example of the operating waveform (analog waveform) of the control and AC generation circuit 42-4 of the control unit 44 in the fourth embodiment. Figure 19 The diagram illustrates an example of a surge voltage generated when the bidirectional semiconductor switch in the AC generation circuit 42-4 is switched from an on state to an off state. Even in Figure 19 When a surge voltage is generated during the operation of the AC generating circuit 42-4 shown, the current path is also related to... Figure 17 The path shown is the same. The following explanation focuses on the action when a surge voltage occurs, with appropriate reference to... Figure 17 The operation of AC generating circuit 42-4 is explained.

[0158] When the control unit 44 switches bidirectional semiconductor switch SW1-2 and bidirectional semiconductor switch SW2-2 from the on state to the off state, and switches bidirectional semiconductor switch SW3-2 from the off state to the on state, the current path is from... Figure 17 The path shown in (d) is switched to Figure 17 The path shown in (a). At this time, during the period when all three bidirectional semiconductor switches SW1-2, SW2-2, and SW3-2 are in a non-conducting state, due to the fact that... Figure 17 In the path shown in (d), the current flowing through the bidirectional semiconductor switch SW1-2 and the bidirectional semiconductor switch SW2-2 (the current before it becomes 0A) generates a surge voltage. Although the surge voltage generated here is absorbed by the bidirectional semiconductor switch SW3-2 turning on, there is concern that the surge voltage before absorption may cause an increase in losses.

[0159] When the control unit 44 switches the bidirectional semiconductor switch SW3-2 from the on state to the off state, and switches the bidirectional semiconductor switches SW1-2 and SW2-2 from the off state to the on state, the current path changes from... Figure 17 The path shown in (b) is switched to Figure 17 The path shown in (c). At this time, during the period P6 when all three bidirectional semiconductor switches SW1-2, SW2-2, and SW3-2 are in a non-conducting state, due to... Figure 17 In the path shown in (b), a surge voltage is generated by the current (the current before it becomes 0A) passing through the bidirectional semiconductor switch SW3-2. Although the surge voltage generated here is absorbed by the bidirectional semiconductor switches SW1-2 and SW2-2 becoming conductive, there is concern that the surge voltage before absorption may cause an increase in losses.

[0160] Thus, in the heating device 40 of the fourth embodiment, when a surge voltage is generated according to the timing of switching the bidirectional semiconductor switch, the loss of the generated alternating current may increase.

[0161] <Fifth Implementation>

[0162] [Structure of the AC generation circuit in the heating device]

[0163] Figure 20 This diagram illustrates an example of the structure of the AC generation circuit 42 (hereinafter referred to as "AC generation circuit 42-5") included in the heating device 40 of the fifth embodiment. Figure 20Also shown is the battery 30 associated with the AC generation circuit 42-5 (the inductor La is omitted from the illustration). The AC generation circuit 42-5 is a structure designed to avoid the surge voltage envisioned in the AC generation circuit 42-4 of the fourth embodiment. The AC generation circuit 42-5 includes, for example, capacitors C1 and C2, switching elements S1a, S1b, S2a, S2b, S3a, S3b, diodes D1a, D1b, D2a, D2b, D3a, and D3b.

[0164] The AC generating circuit 42-5 has the same constituent elements as the AC generating circuit 42-4. Furthermore, the connections of capacitor C1, capacitor C2, bidirectional semiconductor switch SW1-2, bidirectional semiconductor switch SW2-2, and bidirectional semiconductor switch SW3-2 in the AC generating circuit 42-5 are equivalent to those in the AC generating circuit 42-4; that is, they are equivalent to the AC generating circuit 42-1 of the first embodiment. However, in the AC generating circuit 42-5, the control unit 44 controls the switching on or off of the first and second semiconductor switches constituting each bidirectional semiconductor switch at different timings.

[0165] In the following description, the first semiconductor switch section composed of switching element S1a and diode D1a is also referred to as "semiconductor switch section SW1a", and the second semiconductor switch section composed of switching element S1b and diode D1b is also referred to as "semiconductor switch section SW1b". Furthermore, the first semiconductor switch section composed of switching element S2a and diode D2a is also referred to as "semiconductor switch section SW2a", and the second semiconductor switch section composed of switching element S2b and diode D2b is also referred to as "semiconductor switch section SW2b". Additionally, the first semiconductor switch section composed of switching element S3a and diode D3a is also referred to as "semiconductor switch section SW3a", and the second semiconductor switch section composed of switching element S3b and diode D3b is also referred to as "semiconductor switch section SW3b".

[0166] When the control unit 44 changes the bidirectional semiconductor switch SW1-2 and bidirectional semiconductor switch SW2-2 from the on state to the off state, it maintains the on state of either the first or second semiconductor switch constituting the bidirectional semiconductor switch while controlling the other to be off, so that the current flowing in each bidirectional semiconductor switch can be sufficiently reversed. Similarly, when the control unit 44 changes the bidirectional semiconductor switch SW3-2 from the on state to the off state, it maintains the on state of either the first or second semiconductor switch constituting the bidirectional semiconductor switch SW3-2 while controlling the other to be off, so that the current flowing in the bidirectional semiconductor switch SW3-2 can be sufficiently reversed.

[0167] More specifically, when the control unit 44 changes the bidirectional semiconductor switch SW1-2 and bidirectional semiconductor switch SW2-2 from the ON state to the OFF state, it keeps the semiconductor switch on the terminal side with the lower applied voltage value in the ON state while keeping the semiconductor switch on the terminal side with the lower applied voltage value in the ON state, and keeps the semiconductor switch on the terminal side with the higher applied voltage value in the OFF state. Similarly, when the control unit 44 changes the bidirectional semiconductor switch SW3-2 from the ON state to the OFF state, it keeps the semiconductor switch on the terminal side with the lower applied voltage value in the ON state while keeping the semiconductor switch on the terminal side with the lower applied voltage value in the ON state.

[0168] For example, when the voltage values ​​of capacitors C1 and C2 are positive, consider the case where bidirectional semiconductor switches SW1-2 and SW2-2 are changed from an on state to a non-conducting state. In this case, after the control unit 44 changes the second semiconductor switch of bidirectional semiconductor switch SW3-2 from a non-conducting state to an on state, while maintaining the on state of the second semiconductor switch of bidirectional semiconductor switches SW1-2 and SW2-2, it changes the first semiconductor switch of bidirectional semiconductor switches SW1-2 and SW2-2 from an on state to a non-conducting state. For example, when the voltage values ​​of capacitors C1 and C2 are negative, consider the case where bidirectional semiconductor switch SW3-2 is changed from an on state to a non-conducting state. In this case, after the control unit 44 changes the first semiconductor switch of the bidirectional semiconductor switch SW1-2 and the bidirectional semiconductor switch SW2-2 from a non-conducting state to a conducting state, it changes the second semiconductor switch of the bidirectional semiconductor switch SW3-2 from a conducting state to a non-conducting state while maintaining the conducting state of the first semiconductor switch of the bidirectional semiconductor switch SW3-2.

[0169] With this structure, in the AC generating circuit 42-5, similar to the AC generating circuit 42 in the first to fourth embodiments, capacitor C1 and capacitor C2 are connected in parallel or in series between the positive and negative sides of the battery 30 according to the control from the control unit 44.

[0170] In the AC generation circuit 42-5, the structure combining the bidirectional semiconductor switch section SW1-2 and the bidirectional semiconductor switch section SW2-2 is also an example of a "parallel switch section" in the technical solution, and the bidirectional semiconductor switch section SW3-2 is also an example of a "series switch section" in the technical solution. Among the various bidirectional semiconductor switch sections, semiconductor switch sections SW1a, SW2a, and SW3a are examples of a "first semiconductor switch section" in the technical solution. Among the various bidirectional semiconductor switch sections, semiconductor switch sections SW1b, SW2b, and SW3b are examples of a "second semiconductor switch section" in the technical solution.

[0171] [Operation of the heating device]

[0172] Next, the operation of generating alternating current in the alternating current generating circuit 42-5 will be explained. Figure 21 This is a diagram illustrating an example of the operating waveform (analog waveform) of the control and AC generation circuit 42-5 of the control unit 44 in the fifth embodiment. Figure 22 This is a diagram illustrating an example of the path of the alternating current flowing within the alternating current generation circuit 42-5 of the fifth embodiment. Figure 22 In the diagram, "○" indicates that the switching element of each semiconductor switching section is in the ON state, and "×" indicates that the switching element of each semiconductor switching section is in the OFF state. The heating device 40 operates periodically and repeatedly when started by the control device 100; therefore, in the following description, please refer to... Figure 22 Come to Figure 21 The operation of the AC generating circuit 42-5, shown from time t1, will be explained.

[0173] like Figure 22As shown in (a), the control unit 44 sets semiconductor switch SW3a to a non-conducting state, sets semiconductor switch SW3b to a conducting state, sets semiconductor switches SW1a and SW2a to a conducting state, and sets semiconductor switches SW1b and SW2b to a conducting state. In this state, the control unit 44 sets gate signals G1a and G2a to a "low" level and sets semiconductor switches SW1a and SW2a to a non-conducting state during time t1 before the current Ibatt flowing from the battery 30 to charge capacitors C1 and C2 reaches 0A. At this time, since semiconductor switch SW3b is in a conducting state, therefore... Figure 22 As shown in (b), the current obtained based on the current Ibatt flows through the path of the bidirectional semiconductor switch SW3-2 (more specifically, the diode D3a provided in the semiconductor switch SW3b and semiconductor switch SW3a). Furthermore, as... Figure 22 As shown in (c), the control unit 44 sets the gate signal G3a to a "high" level, thus turning on the semiconductor switch SW3a. Therefore, in the AC generation circuit 42-5, there will be no... Figure 22 In the path shown in (a), the current obtained based on the current Ibatt (the current before it becomes 0A) passes through the bidirectional semiconductor switch section SW1-2 and the bidirectional semiconductor switch section SW2-2, and a surge voltage is generated during P1. Then, in the AC generation circuit 42-5, the current Ibatt continues to flow in the direction that discharges the battery 30, and the voltage Vcap continues to rise.

[0174] Then, at time t2, when voltage Vcap becomes a positive peak voltage, in the AC generating circuit 42-5, the direction of the current (current Icap) in capacitors C1 and C2 reverses, and capacitors C1 and C2 discharge respectively. Figure 22 In the opposite direction of the path shown in (c), currents Is3 and Icap flow in the direction of charging battery 30. Therefore, in the AC generating circuit 42-5, during period P2, voltage Vcap begins to decrease, current Ibatt continues to increase, and then begins to decrease.

[0175] During a predetermined timing within period P2, for example, at time t3 when voltage Vcap becomes 0V, control unit 44 sets gate signals G1b and G2b to a "low" level, thus deactivating semiconductor switches SW1b and SW2b. Furthermore, control unit 44 sets gate signals G1a and G2a to a "high" level, thus enabling semiconductor switches SW1a and SW2a to conduct. Consequently, in AC generation circuit 42-5, the currents (current Is3 and current Icap) after capacitors C1 and C2 have discharged respectively pass through... Figure 22 The path shown in (d) continues to flow in the direction of charging the battery 30.

[0176] Subsequently, during the time t4 before the current Is3 flowing in the bidirectional semiconductor switch SW3-2 becomes 0A, the control unit 44 sets the gate signal G3b to a "low" level, thus making the semiconductor switch SW3b non-conducting. At this time, since the semiconductor switch SW3a is in the conducting state, therefore, Figure 22 As shown in (e), the current obtained based on the current Ibatt flows continuously through the paths of capacitors C1 and C2, and the diode D3b of semiconductor switching units SW3a and SW3b, respectively. Therefore, no surge voltage is generated during the period P3 up to time t5.

[0177] In addition, such as Figure 22 As shown in (f), the control unit 44 sets the gate signals G1b and G2b to a "high" level, thus turning on the semiconductor switches SW1b and SW2b. A reverse voltage is then applied to the diode D3b, which carries a forward current. Therefore, during reverse recovery, a temporary reverse current is generated in diode D3b, but this temporary current immediately converges. Then, in the AC generation circuit 42-5, the current Ibatt continues to decrease, the current direction changes to the direction of discharging the battery 30, and the voltage Vcap begins to rise.

[0178] During a predetermined timing within period P4, for example, at time t6 when the voltage Vcap becomes 0V, control unit 44 sets the gate signal G3a to a "low" level, thus deactivating semiconductor switch SW3a. Furthermore, control unit 44 sets the gate signal G3b to a "high" level, thus enabling semiconductor switch SW3b to conduct. Consequently, in AC generation circuit 42-5, the circuit returns to the same path as during period P1. Figure 22 (The path shown in (a)). Then, the same actions are repeated periodically.

[0179] Thus, in the heating device 40 of the fifth embodiment, the on / off state of the first and second semiconductor switches of each bidirectional semiconductor switch unit included in the AC generating circuit 42-4 of the fourth embodiment is controlled at different timings. More specifically, in the AC generating circuit 42-5, when a bidirectional semiconductor switch unit in the conducting state is turned off, the control is such that after either the first or second semiconductor switch unit constituting the other bidirectional semiconductor switch unit has been turned on beforehand, the bidirectional semiconductor switch unit in the conducting state is turned off, so that the current flowing in the bidirectional semiconductor switch unit can be sufficiently returned. Therefore, in the heating device 40 of the fifth embodiment, even if the control of turning off the bidirectional semiconductor switch unit in the conducting state is not performed by ZCS control, that is, even if the switching is performed at a timing separated from the position where the AC current is approximately 0A, the surge voltage imagined in the voltage Vbatt can be avoided. Therefore, in the heating device 40 of the fifth embodiment, the increase in the loss of the AC current generated by the AC generating circuit 42-5 can be suppressed, and the battery 30 can be heated more efficiently by the generated AC current.

[0180] Here, the characteristics of the AC current generated by the AC generating circuit 42-4 of the fourth embodiment and the AC generating circuit 42-5 of the fifth embodiment, as well as the loss of the generated AC current, will be explained. Figure 23 This is a graph comparing the amplitude characteristics and losses of the AC current generated by AC generating circuits 42 (AC generating circuits 42-4 and 42-5). Figure 23 In (a), the characteristics of the effective value (rms value) of the current value representing the amplitude of the AC current generated by AC generation circuits 42-4 and 42-5, respectively, are shown when the duty cycle is set to the same and the frequency is varied. Figure 23 In (b), the magnitude of the circuit losses (Watt) when AC generating circuits 42-4 and 42-5 generate AC current is shown. Figure 23 As shown in (a), the variation in the amplitude (current value) of the generated alternating current is approximately the same in both AC generating circuit 42-4 and AC generating circuit 42-5. In contrast, as... Figure 23 As shown in (b), over the entire frequency band of the generated alternating current, the circuit loss of AC generating circuit 42-5 is lower than that of AC generating circuit 42-4. Therefore, it can be concluded that AC generating circuit 42-5 can generate an alternating current with the same amplitude as AC generating circuit 42-4 with less circuit loss.

[0181] In the above Figure 21The description addresses the case where the control unit 44, at a timing when the voltage Vcap becomes 0V, prematurely turns on either the first or second semiconductor switch constituting the other bidirectional semiconductor switch. However, the timing at which the control unit 44 prematurely turns on either semiconductor switch can be any timing, as long as it precedes the timing at which the bidirectional semiconductor switch in the on state becomes non-conductive. In other words, the control unit 44 only needs to ensure the logic when the bidirectional semiconductor switch in the on state becomes non-conductive. This can be determined similarly to the AC generation circuit 42 in the first to fourth embodiments by measuring (monitoring) the components of the AC generation circuit 42, the current value of the battery 30, and the voltage value, or based on the operating state of the AC generation circuit 42.

[0182] Thus, in the heating device 40 of the fifth embodiment, each semiconductor switch of the bidirectional semiconductor switch unit constituting the AC generating circuit 42-5 is controlled at different timings. Therefore, in the heating device 40 of the fifth embodiment, there is no need to worry about unintended current paths as in the AC generating circuit 42-1 (see [reference]). Figure 7 The formation of the AC generation circuit 42-4 and the increase in losses caused by the surge voltage can maintain the resonant operation of the inductance La of the battery 30, thereby generating an AC current with a sufficient amplitude (wider than the AC generation circuit 42-1). Therefore, in the heating device 40 of the fifth embodiment, the battery 30 can be heated more efficiently by the generated AC current.

[0183] Here, an example of implementing the control unit 44 using logic circuits will be explained. Figure 24 This is a circuit diagram illustrating an example of the circuit structure of the control unit 44. The control unit 44 includes, for example, a comparator 441, a NOT circuit (NOT circuit or inverter circuit) 442, and four OR circuits 443 to 446. With this structure, the control unit 44 implements the logical operation expression of the following formula (1).

[0184] PLS-P = Vcap = 0

[0185] PLS-N = ~PLS-P

[0186] G1a=G2a=PLS-A∨PLS-N

[0187] G1b=G2b=PLS-A∨PLS-P

[0188] G3a=PLS-B∨PLS-N

[0189] G3b=PLS-B∨PLS-P···(1)

[0190] In equation (1) above, pulse signal PLS-A is a control signal indicating that capacitor C1 and capacitor C2 are connected in parallel. PLS-B is a control signal indicating that capacitor C1 and capacitor C2 are connected in series. PLS-P is a control signal indicating that the voltage Vcap (i.e., the voltage of capacitor C1) is positive (plus). PLS-N is a control signal indicating that the voltage of capacitor C1 is negative (minus). PLS-A and PLS-B can be output from control device 100 to control unit 44, for example, or they can be generated by a pulse generator (not shown) provided in control unit 44, such as a clock generator, based on information about the period (frequency) and duty cycle of the alternating current indicated by control device 100.

[0191] Figure 25 This is an example of a timing diagram showing the timing of the gate signal generated by the control unit 44. Figure 25 In, with Figure 21 An example of the operating waveform (analog waveform) of the AC generating circuit 42-5 shown is illustrated. Figure 24 The control unit 44, implemented by the logic circuit shown, generates the timing of gate signals G1a, G1b, G2a, G2b, G3a, and G3b. The control unit 44 outputs a pulse signal PLS-P based on the input periodically changing pulse signals PLS-A and PLS-B, the pulse signal PLS-P resulting from the comparison of the voltage Vcap level with the ground level by comparator 441, and the pulse signal PLS-P output after the NOT circuit 442 inverts the pulse signal PLS-P. Figure 25 The timing of each gate signal is shown.

[0192] More specifically, in Figure 25 In this circuit, the voltage Vcap is negative during periods P1 and P3, and positive during period P2. Therefore, comparator 441 outputs a low-level pulse signal PLS-P during periods P1 and P3, and a high-level pulse signal PLS-P during period P2. The NOT circuit 442 outputs a pulse signal PLS-N that inverts the PLS-P output by comparator 441. The OR circuits 443 to 446 output the ORed signals of the input pulse signals as their respective gate signals.

[0193] In use Figure 24 and Figure 25The logic circuit structure and operation timing of the control unit 44 described herein show a logic circuit structure that monitors the voltage value Vcap and generates individual gate signals based on whether Vcap is a positive or negative voltage value. However, as described above, the control unit 44 may also generate gate signals by monitoring the current or voltage values ​​of any component of the AC generation circuit 42-5. In this case, the logic circuit structure, operation timing, and... Figure 24 The logic circuit structure shown and Figure 25 The timing diagram shown can be equivalent. Furthermore, the control unit 44 is not limited to a structure implemented by logic circuits. That is, the operation of the control unit 44 can also be implemented by executing a program using a hardware processor such as a CPU provided with the control unit 44 (or the control device 100). In this case, the program can be, for example, a program that implements an operation equivalent to the logical operation expression in equation (1) above.

[0194] As described above, according to the heating device 40 of each embodiment, by switching the connection of capacitors C1 and C2 in the AC generating circuit 42 to the battery 30 to a series connection or a parallel connection, an alternating current based on the power stored in the battery 30 is generated by the resonant operation of alternatingly exchanging the magnetic energy stored in the inductor La of the battery 30 and the electrostatic energy stored in at least capacitor C1. Therefore, in the heating device 40 of each embodiment, the battery 30 can be heated more efficiently by the generated alternating current. Thus, in the vehicle 1 using the heating device 40 of each embodiment, the battery 30 can be used at a suitable temperature, and the degradation of the charging and discharging performance of the battery 30 can be suppressed.

[0195] The heating device 40 according to the embodiments described above includes an AC generating circuit 42 and a control unit 44. The AC generating circuit 42 generates an AC current based on the power stored in the battery 30 having an inductor La, and includes: a capacitor C1, the first end of which is connected to the positive terminal of the battery 30; a capacitor C2, the first end of which is connected to the negative terminal of the battery 30; a parallel switch unit that connects the second terminal of capacitor C1 to the first terminal of capacitor C2 and the first terminal of capacitor C1 to the second terminal of capacitor C2, thereby connecting capacitor C1 and capacitor C2 in parallel with the battery 30; and a series switch unit that connects the second terminal of capacitor C1 to the second terminal of capacitor C2, thereby connecting capacitor C1 and capacitor C2 in parallel with the battery 30; and a series switch unit that connects the second terminal of capacitor C1 to the second terminal of capacitor C2, thereby connecting capacitor C1 and capacitor C2 in series with the battery 30. Device C2 is connected in series with battery 30. Control unit 44 alternately switches between a parallel connection state where the parallel switch is turned on and the series switch is turned off, and a series connection state where the parallel switch is turned off and the series switch is turned on. When turning the parallel switch from off to on, control unit 44 turns the parallel switch from off to on after turning the series switch from on to off. Similarly, when turning the series switch from off to on, control unit 44 turns the series switch from off to on after turning the parallel switch from on to off. This allows for more efficient heating of the battery 30 used in vehicle 1. Therefore, in vehicle 1 employing the heating device 40 of each embodiment, the battery 30 can be used at a suitable temperature, suppressing any decrease in the charging and discharging performance of the battery 30. Therefore, in the vehicle 1 equipped with the heating device 40 of each embodiment, the product quality of the vehicle 1, such as durability, can be improved. Thus, 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 effects on the Earth's environment.

[0196] In the above embodiments, the structure of the control device 100 of the vehicle 1 controlling the operation of the heating device 40 was described. That is, in the above embodiments, the control device for controlling the operation of the heating device 40 was described as being configured within the control device 100 of the vehicle 1. However, the control of the operation of the heating device 40 can also be performed by the control unit 44 of the heating device 40. In this case, the control unit 44 of the heating device 40 obtains battery information (especially information about the temperature of the battery 30) directly from the battery sensor 32 connected to the battery 30 or via the control device 100 of the vehicle 1, thereby enabling control of the operation of the heating device 40 in the above embodiments. The structure, operation, and processing of the heating device 40 and the control unit 44 in this case can be equivalent to the structure, operation, and processing of the heating device 40 and the control device 100 in the above embodiments.

[0197] The implementation methods described above can be performed as follows.

[0198] A heating device comprising an AC power generation circuit and a control unit.

[0199] The AC generating circuit generates an AC current based on the electricity stored in a storage element, the storage element having an inductive component.

[0200] The AC generating circuit has:

[0201] A first capacitor, the first end of which is connected to the positive terminal side of the energy storage body;

[0202] A second capacitor, the first end of which is connected to the negative terminal side of the energy storage body;

[0203] A parallel switching section 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 with the energy storage body; and

[0204] A series switch 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 with the energy storage device.

[0205] The control unit alternately switches between a first state where the parallel switch section is turned on and the series switch section is turned off, and a second state where the parallel switch section is turned off and the series switch section is turned on.

[0206] The control unit includes a hardware processor and a storage device storing programs.

[0207] The control unit is configured to read and execute a program stored in the storage device via the hardware processor to perform the following processing:

[0208] When the parallel switch is switched from a non-conducting state to a conducting state, after the series switch is switched from a conducting state to a non-conducting state, the parallel switch is switched from a non-conducting state to a conducting state; and

[0209] When the series switch is switched from a non-conducting state to a conducting state, after the parallel switch is switched from a conducting state to a non-conducting state, the series switch is switched from a non-conducting state to a conducting state.

[0210] 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. A heating device, wherein, The heating device includes an AC power generation circuit and a control unit. The AC generating circuit generates an AC current based on the electricity stored in a storage element, the storage element having an inductive component. The AC generating circuit has: 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; A parallel switching section 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 with the energy storage body. as well as A series switch 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 with the energy storage device. The control unit alternately switches between a first state where the parallel switch section is turned on and the series switch section is turned off, and a second state where the parallel switch section is turned off and the series switch section is turned on. The parallel switching section and the series switching section each include at least one semiconductor switching section, which is formed by connecting semiconductor switching elements controlled by the control section to a diode in parallel. The parallel switching section and the series switching section each have a first semiconductor switching section and a second semiconductor switching section connected in series as semiconductor switching sections, wherein the diodes in the first semiconductor switching section and the second semiconductor switching section are oriented in opposite directions. When the parallel switch section is changed from a non-conducting state to a conducting state, the control unit, after changing the series switch section from a conducting state to a non-conducting state, changes the parallel switch section from a non-conducting state to a conducting state. When the series switch is switched from a non-conducting state to a conducting state, the control unit, after switching the parallel switch from a conducting state to a non-conducting state, switches the series switch from a non-conducting state to a conducting state. When the control unit switches from a state where the first capacitor and the second capacitor are connected in parallel with the energy storage body to a state where the first capacitor and the second capacitor are connected in series with the energy storage body by setting the parallel switch to the on state, after setting either the first semiconductor switch or the second semiconductor switch of the series switch to the on state, and after keeping either the first semiconductor switch or the second semiconductor switch of the parallel switch in the on state, it switches to a state where the first capacitor and the second capacitor are connected in series with the energy storage body, so that the current flowing in the parallel switch can flow back. When the control unit switches from a state in which the first capacitor and the second capacitor are connected in series with the energy storage body to a state in which the first capacitor and the second capacitor are connected in parallel with the energy storage body by setting the series switch to the on state, after setting either the first semiconductor switch or the second semiconductor switch of the parallel switch to the on state, and after keeping either the first semiconductor switch or the second semiconductor switch of the series switch in the on state, it switches to a state in which the first capacitor and the second capacitor are connected in parallel with the energy storage body, so that the current flowing in the series switch can flow back.

2. The heating device according to claim 1, wherein, The control unit controls the conduction and non-conducting states of the parallel switch and the series switch based on the voltage value of the first capacitor or the voltage value of the second capacitor.

3. The heating device according to claim 1, wherein, The control unit controls the conduction and non-conductivity states of the parallel switch and the series switch based on the voltage values ​​of the positive and negative terminals of the energy storage element.

4. The heating device according to claim 1, wherein, The control unit controls the conduction and non-conducting states of the parallel switch section and the series switch section based on the voltage values ​​across the two ends of the parallel switch section or the series switch section when they are in a non-conducting state.

5. The heating device according to claim 1, wherein, The control unit controls the conduction and non-conducting states of the parallel switch section and the series switch section based on the current value of the alternating current flowing in the parallel switch section or the series switch section.

6. The heating device according to claim 1, wherein, The control unit controls the conduction and non-conducting states of the parallel switch section and the series switch section at a predetermined timing based on the alternating current.

7. The heating device according to claim 6, wherein, The specified timing is determined based on the period or duty cycle of the alternating current.

8. A control method for a heating device, the heating device comprising an AC generation circuit and a control unit, The AC generating circuit generates an AC current based on the electricity stored in a storage element, the storage element having an inductive component. The AC generating circuit has: 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; A parallel switching section 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 with the energy storage body. as well as A series switch 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 with the energy storage device. The control unit alternately switches between a first state where the parallel switch section is turned on and the series switch section is turned off, and a second state where the parallel switch section is turned off and the series switch section is turned on. The parallel switching section and the series switching section each include at least one semiconductor switching section, which is formed by connecting semiconductor switching elements controlled by the control section to a diode in parallel. The parallel switching section and the series switching section each have a first semiconductor switching section and a second semiconductor switching section connected in series as semiconductor switching sections, wherein the diodes in the first semiconductor switching section and the second semiconductor switching section are oriented in opposite directions. In the control method of the heating device, The computer in the control unit performs the following processing: When the parallel switch section is changed from a non-conducting state to a conducting state, after the series switch section is changed from a conducting state to a non-conducting state, the parallel switch section is changed from a non-conducting state to a conducting state. When the series switch is changed from a non-conducting state to a conducting state, after the parallel switch is changed from a conducting state to a non-conducting state, the series switch is changed from a non-conducting state to a conducting state. When switching from a state in which the first capacitor and the second capacitor are connected in parallel with the energy storage body to a state in which the first capacitor and the second capacitor are connected in series with the energy storage body by setting the parallel switch to the on state, after setting either the first semiconductor switch or the second semiconductor switch of the series switch to the on state, and after keeping either the first semiconductor switch or the second semiconductor switch of the parallel switch in the on state, the switch is made to a state in which the first capacitor and the second capacitor are connected in series with the energy storage body so that the current flowing through the parallel switch can flow back; as well as When switching from a state where the first capacitor and the second capacitor are connected in series with the energy storage body to a state where the first capacitor and the second capacitor are connected in parallel with the energy storage body by setting the series switch to the on state, after setting either the first semiconductor switch or the second semiconductor switch of the parallel switch to the on state, and after keeping either the first semiconductor switch or the second semiconductor switch of the series switch in the on state, the switch switches to a state where the first capacitor and the second capacitor are connected in parallel with the energy storage body so that the current flowing through the series switch can flow back.

9. A storage medium, wherein, The storage medium stores a program that controls the heating device. The heating device includes an AC power generation circuit and a control unit. The AC generating circuit generates an AC current based on the electricity stored in a storage element, the storage element having an inductive component. The AC generating circuit has: 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; A parallel switching section 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 with the energy storage body. as well as A series switch 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 with the energy storage device. The control unit alternately switches between a first state where the parallel switch section is turned on and the series switch section is turned off, and a second state where the parallel switch section is turned off and the series switch section is turned on. The parallel switching section and the series switching section each include at least one semiconductor switching section, which is formed by connecting semiconductor switching elements controlled by the control section to a diode in parallel. The parallel switching section and the series switching section each have a first semiconductor switching section and a second semiconductor switching section connected in series as semiconductor switching sections, wherein the diodes in the first semiconductor switching section and the second semiconductor switching section are oriented in opposite directions. The program causes the computer in the control unit to perform the following processing: When the parallel switch section is changed from a non-conducting state to a conducting state, after the series switch section is changed from a conducting state to a non-conducting state, the parallel switch section is changed from a non-conducting state to a conducting state. When the series switch is changed from a non-conducting state to a conducting state, after the parallel switch is changed from a conducting state to a non-conducting state, the series switch is changed from a non-conducting state to a conducting state. When switching from a state in which the first capacitor and the second capacitor are connected in parallel with the energy storage body to a state in which the first capacitor and the second capacitor are connected in series with the energy storage body by setting the parallel switch to the on state, after setting either the first semiconductor switch or the second semiconductor switch of the series switch to the on state, and after keeping either the first semiconductor switch or the second semiconductor switch of the parallel switch in the on state, the switch is made to a state in which the first capacitor and the second capacitor are connected in series with the energy storage body so that the current flowing through the parallel switch can flow back; as well as When switching from a state where the first capacitor and the second capacitor are connected in series with the energy storage body to a state where the first capacitor and the second capacitor are connected in parallel with the energy storage body by setting the series switch to the on state, after setting either the first semiconductor switch or the second semiconductor switch of the parallel switch to the on state, and after keeping either the first semiconductor switch or the second semiconductor switch of the series switch in the on state, the switch switches to a state where the first capacitor and the second capacitor are connected in parallel with the energy storage body so that the current flowing through the series switch can flow back.

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