Alternating current generation circuit and temperature raising device

Abstract

Provided is an alternating-current generation circuit. The alternating-current generation circuit includes a first capacitor having a first terminal connected to a positive electrode side of an electricity storage body having an inductive component, a second capacitor having a second terminal connected to a negative electrode side of the electricity storage body, a third capacitor having a second terminal connected to the negative electrode side of the electricity storage body, a fourth capacitor having a first terminal connected to the positive electrode side of the electricity storage body, a first switch having a first terminal connected to the first terminal of the first capacitor and a second terminal, a second switch having a second terminal connected to the second terminal of the first capacitor and a first terminal, a third switch having a second terminal connected to the second terminal of the third capacitor and a first terminal, a fourth switch having a first terminal connected to the first terminal of the third capacitor and a second terminal, a first inductor connected between the second terminal of the first switch and the first terminal of the fourth switch, and a second inductor connected between the second terminal of the second switch and the first terminal of the third switch.

Description

Technical Field

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

[0002] Efforts are underway to mitigate the adverse environmental impacts on Earth (e.g., NOx and SOx reduction, CO2 reduction). Therefore, in recent years, from the perspective of improving the Earth's environment and reducing CO2, there has been a growing focus on electric vehicles, such as hybrid electric vehicles (HEVs) or plug-in hybrid electric vehicles (PHEVs), which are powered by electric motors powered by electricity supplied by batteries (secondary batteries). Furthermore, the use of lithium-ion secondary batteries as onboard batteries 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 secondary battery to a suitable operating temperature, the decline in charge and discharge performance can be suppressed.

[0003] Relatedly, for example, Japanese Patent No. 5293820 discloses 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.

[0004] However, in the existing technology, it is sometimes impossible to heat up the secondary battery efficiently. Summary of the Invention

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

[0006] means for solving problems

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

[0008] (1): An AC generating circuit of one aspect of the present invention heats up the energy storage body by generating an AC current based on the power stored in the energy storage body having an inductive component, wherein the AC generating circuit comprises: a first capacitor, the first terminal of which is connected to the positive terminal side of the energy storage body; a second capacitor, the first terminal of which is connected to the second terminal of the first capacitor and the second terminal of which is connected to the negative terminal side of the energy storage body; a third capacitor, the second terminal of which is connected to the negative terminal side of the energy storage body; a fourth capacitor, the second terminal of which is connected to the first terminal of the third capacitor and the first terminal of which is connected to the positive terminal side of the energy storage body; and a first switch. A first terminal is connected to the first terminal of the first capacitor; a second switch, the first terminal of which is connected to the second terminal of the first switch, and the second terminal of the second switch is connected to the second terminal of the first capacitor; a third switch, the second terminal of which is connected to the second terminal of the third capacitor; a fourth switch, the second terminal of which is connected to the first terminal of the third switch, and the first terminal of the fourth switch is connected to the first terminal of the third capacitor; a first inductor connected between the second terminal of the first switch and the first terminal of the fourth switch; and a second inductor connected between the second terminal of the second switch and the first terminal of the third switch.

[0009] (2): Based on the above (1) scheme, the inductance of the first inductor, the inductance of the second inductor, the capacitance of the first capacitor, the capacitance of the second capacitor, the capacitance of the third capacitor and the capacitance of the fourth capacitor are adjusted based on the relationship containing the inductance component so that the current waveform of the alternating current is close to a sine wave.

[0010] (3): Based on the above (2) scheme, the inductance of the first inductor and the inductance of the second inductor are equal.

[0011] (4): Based on the above (3) scheme, the capacitance of the first capacitor and the capacitance of the third capacitor are equal to the first capacitor.

[0012] (5): Based on the above scheme (4), the capacitance of the second capacitor and the capacitance of the fourth capacitor are equal to the second capacitance.

[0013] (6): Based on the above scheme (5), the second capacitor is a capacitor smaller than twice the capacitance of the first capacitor.

[0014] (7): Based on the above scheme (5), the second capacitor is a capacitor that is three times larger than the first capacitor.

[0015] (8): Based on the above scheme (5), the second capacitor and the first capacitor are equal in capacitance.

[0016] (9): Based on any of the above schemes (1) to (8), the inductance component includes the inductance component present in the wiring portion between the energy storage body and the AC generating circuit.

[0017] (10): Based on any of the above schemes (1) to (9), the first switch and the third switch are controlled to be in a conducting state or a non-conducting state according to the first control signal, and the second switch and the fourth switch are controlled to be in a conducting state or a non-conducting state according to the second control signal. The period during which the first control signal makes the first switch and the third switch in a conducting state and the period during which the second control signal makes the second switch and the fourth switch in a conducting state are non-overlapping periods.

[0018] (11): Based on the above (10) scheme, the energy storage body includes a first energy storage body and a second energy storage body connected in series with the first energy storage body. The AC generating circuit is connected to the first energy storage body, and the second AC generating circuit with the same structure as the AC generating circuit is connected to the second energy storage body. The first control signal and the second control signal are input in such a way that a predetermined phase difference is given between the AC current generated by the AC generating circuit and the AC current generated by the second AC generating circuit, i.e., the second AC current.

[0019] (12): A heating device according to one aspect of the present invention includes: an AC generating circuit of the above-described (11) aspect; and a control unit that outputs a first control signal and a second control signal, and alternately switches between a first state and a second state by means of the first control signal and the second control signal. In the first state, the first switch and the third switch are set to a non-conducting state, and the second switch and the fourth switch are set to a conducting state. In the second state, the first switch and the third switch are set to a conducting state, and the second switch and the fourth switch are set to a non-conducting state.

[0020] Invention Effects

[0021] According to the schemes (1) to (12) above, energy efficiency can be improved by making the secondary battery heat up more efficiently. Attached Figure Description

[0022] Figure 1This is a diagram illustrating an example of the structure of a vehicle employing the heating device of the embodiment.

[0023] Figure 2 This is a diagram illustrating an example of the structure of the AC generation circuit included in the heating device of the embodiment.

[0024] Figure 3 This is an example of an equivalent circuit connected in series in the AC generation circuit of the implementation method.

[0025] Figure 4 This is an example of an equivalent circuit connected in parallel in the AC generating circuit of the implementation method.

[0026] Figure 5 This is a diagram illustrating an example of the structure of the AC generating circuit of the comparative example.

[0027] Figure 6 This is an example of the equivalent circuit of the AC generating circuit in the comparative example.

[0028] Figure 7 This is a diagram illustrating an example of the relationship between the capacitance of a capacitor and the resonant frequency in an AC generation circuit according to an embodiment.

[0029] Figure 8 This is an example of an equivalent circuit used to illustrate the resonant frequency of the alternating current generated in the alternating current generation circuit of the embodiment.

[0030] Figure 9 This is a diagram illustrating an example of the frequency characteristics of the alternating current generated in the alternating current generation circuit of the embodiment.

[0031] Figure 10 This is a diagram illustrating an example of the operating waveform of a heating device employing a comparative example of an AC generating circuit.

[0032] Figure 11 This is a diagram illustrating an example of the operating waveform of a heating device employing an AC generating circuit according to an embodiment.

[0033] Figure 12 This is another example of the operating waveform of a heating device employing an AC generating circuit according to the embodiment. Detailed Implementation

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

[0035] [Vehicle Structure]

[0036] Figure 1This diagram illustrates an example of the structure of a vehicle employing the heating device of the embodiment. Vehicle 1 is a hybrid electric vehicle (HEV) (hereinafter simply referred to as "vehicle") that travels by a combination of driving an electric motor (electric motor) powered by electricity supplied from a driving battery (secondary battery) or by driving an internal combustion engine powered by fuel, 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 straddle-type two-wheeled vehicles, three-wheeled vehicles (including vehicles with two front wheels and one rear wheel in addition to those with one front wheel and two rear wheels), and auxiliary bicycles, etc., all of which are driven by an electric motor, 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 driving an electric motor (electric motor).

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

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

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

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

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

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

[0043] The storage battery 30 is an example of an "energy storage body". The inductive component of the storage battery 30 (the inductive component of the storage battery 30 connected to the energy storage unit) is an example of an "inductive component".

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

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

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

[0047] The control unit 44 switches the connection between each capacitor and the battery 30 to either a series connection or a parallel connection by setting the series switch and the parallel switch of the AC generating circuit 42 to a conducting state or a non-conducting state, respectively. More specifically, the control unit 44 alternately switches between the following two states: connecting each capacitor to the battery 30 in series by setting the series switch to a conducting state and the parallel switch to a non-conducting state; and connecting each capacitor to the battery 30 in parallel by setting the series switch to a non-conducting state and the parallel switch to a conducting state. At this time, the control unit 44 can also switch the connection between each capacitor and the battery 30 from a series connection to a parallel connection, or from a parallel connection to a series connection, in a manner in which the periods when both the series switch and the parallel switch are set to a conducting state do not overlap. In other words, the control unit 44 can also be set to a period during which both the series switch unit and the parallel switch unit are set to a non-conducting state, i.e., the so-called dead time, to switch the connection between each capacitor and the battery 30 from series connection to parallel connection, or from parallel connection to series connection.

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

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

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

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

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

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

[0054] [The structure of the AC generation circuit in the heating device]

[0055] Figure 2This diagram illustrates an example of the structure of the AC generation circuit 42 included in the heating device 40 of the embodiment. Figure 2 Also shown is a battery 30 associated with the AC generating circuit 42. For example, a resistor Ra and an inductor La are connected in series on the positive terminal side of the battery 30, connected to the energy storage unit Ba. The inductor La connected to the energy storage unit Ba in the battery 30 is an example of an "inductive component".

[0056] The AC generating circuit 42 includes, for example, capacitors C10, C11, C20, and C21, switches S11, S12, S21, and S22, inductor L10, and inductor L20.

[0057] The first terminal of capacitor C10 is connected to the positive terminal of battery 30. Furthermore, the first terminal of capacitor C10 is connected to the first terminal of switch S11 and the first terminal of capacitor C21. The second terminal of capacitor C10 is connected to the first terminal of capacitor C11. Furthermore, the second terminal of capacitor C10 is connected to the second terminal of switch S12 and the first terminal of inductor L20. The second terminal of capacitor C11 is connected to the negative terminal of battery 30. Furthermore, the second terminal of capacitor C11 is connected to the second terminal of switch S21 and the second terminal of capacitor C20. The first terminal of capacitor C20 is connected to the second terminal of capacitor C21. Furthermore, the first terminal of capacitor C20 is connected to the first terminal of switch S22 and the second terminal of inductor L10. The second terminal of switch S11 is connected to the first terminal of switch S12 and the first terminal of inductor L10. The first terminal of switch S21 is connected to the second terminal of switch S22 and the second terminal of inductor L20.

[0058] Capacitors C10 and C20 are respectively switched between being connected in series with battery 30 and in parallel with battery 30. By switching capacitors C10 and C20 to the states of being connected in series with battery 30 and in parallel with battery 30, respectively, alternating current (ripple current) is generated through resonant operation with the inductive component of battery 30. Capacitors C10 and C20 are capacitors with equal electrostatic capacitance. Capacitors C11, C21, inductors L10 and L20 are structural elements that make the overall impedance of the AC generating circuit 42 the same, depending on whether capacitors C10 and C20 are connected in series with battery 30 or in parallel with battery 30. Capacitors C11 and C21 are capacitors with equal capacitance. Inductors L10 and L20 are inductors with equal inductance.

[0059] Switches S11, S12, S21, and S22 are controlled by the control signal output from the control unit 44 to either a conducting state (connecting the terminals of both sides, becoming a closed state) or a non-conducting state (not connecting the terminals of both sides, becoming an open state). Switches S12 and S22 are controlled by the control unit 44 to form a series switch that connects capacitors C10 and C20 in series with the battery 30. Switches S11 and S21 are controlled by the control unit 44 to form a parallel switch that connects capacitors C10 and C20 in parallel with the battery 30.

[0060] Switches S11, S12, S21, and S22 can each be, for example, an N-channel metal oxide semiconductor field-effect transistor (MOSFET), which is controlled to be either on or off. In this case, a structure further connected in parallel with a diode that functions as a freewheeling diode can also be used. When switches S11, S12, S21, and S22 are each composed of semiconductor switching elements, the control unit 44 outputs a gate signal that makes the semiconductor switching elements in an on or off state, serving as a control signal to control switches S11, S12, S21, and S22 to be in a conducting or non-conducting state, respectively.

[0061] In the following description, the control signal output by the control unit 44 that controls switch S11 to a conducting or non-conducting state is called "control signal CS11"; the control signal output by the control unit 44 that controls switch S12 to a conducting or non-conducting state is called "control signal CS12"; the control signal output by the control unit 44 that controls switch S21 to a conducting or non-conducting state is called "control signal CS21"; and the control signal output by the control unit 44 that controls switch S22 to a conducting or non-conducting state is called "control signal CS22". When switches S12 and S22 are simultaneously controlled as series switches and switches S11 and S21 are simultaneously controlled as parallel switches, the control unit 44 may also output control signals CS12 and CS22 as the same control signal CS, and control signals CS11 and CS21 as the same control signal CS.

[0062] With this structure, in the AC generating circuit 42, according to the control from the control unit 44, capacitors C10 and C20 are connected in series or in parallel between the positive and negative terminals of the battery 30. More specifically, the control unit 44 outputs a control signal CS11 to switch S11 to make it non-conducting, a control signal CS21 to switch S21 to make it non-conducting, a control signal CS12 to switch S12 to make it conducting, and a control signal CS22 to switch S22 to make it conducting. Thus, capacitors C10 and C20 are connected in series between the positive and negative terminals of the battery 30. On the other hand, the control unit 44 outputs a control signal CS11 to switch S11 to make it in the conducting state, a control signal CS21 to switch S21 to make it in the conducting state, a control signal CS12 to switch S12 to make it in the non-conducting state, and a control signal CS22 to switch S22 to make it in the non-conducting state. As a result, capacitors C10 and C20 are connected in parallel between the positive and negative terminals of the battery 30.

[0063] In the AC generating circuit 42, capacitor C10 is an example of a "first capacitor," capacitor C11 is an example of a "second capacitor," capacitor C20 is an example of a "third capacitor," and capacitor C21 is an example of a "fourth capacitor." In the AC generating circuit 42, switch S11 is an example of a "first switch," switch S12 is an example of a "second switch," switch S21 is an example of a "third switch," and switch S22 is an example of a "fourth switch." In the AC generating circuit 42, inductor L10 is an example of a "first inductor," and inductor L20 is an example of a "second inductor." The control signal CS11 output by control unit 44 to switch S11 and the control signal CS21 output by control unit 44 to switch S21 are examples of "first control signals," and the control signal CS12 output by control unit 44 to switch S12 and the control signal CS22 output by control unit 44 to switch S22 are examples of "second control signals." The state in which the control unit 44 makes switches S11 and S21 non-conducting through control signals CS11 and CS21, and makes switches S12 and S22 both conducting through control signals CS12 and CS22, is an example of the "first state". The state in which the control unit 44 makes switches S11 and S21 conducting through control signals CS11 and CS21, and makes switches S12 and S22 non-conducting through control signals CS12 and CS22, is an example of the "second state".

[0064] [Operation of the AC generating circuit]

[0065] Here, the frequency of the alternating current generated by the alternating current generating circuit 42 is considered. In order to efficiently heat the battery 30 through the heating device 40, it is preferable that the current waveform of the alternating current generated by the alternating current generating circuit 42 is a sine wave.

[0066] However, as described above, in the AC generation circuit 42, capacitors C10 and C20 are capacitors with equal electrostatic capacitance (capacitance). Therefore, in the AC generation circuit 42, the overall capacitance differs depending on whether capacitors C10 and C20 are connected in series with the battery 30 or in parallel with the battery 30, considering them as a single capacitor. More specifically, when capacitors C10 and C20 are connected in series, the overall capacitance of the AC generation circuit 42 is the sum of the reciprocals of the individual capacitor capacitances, i.e., half the capacitance. On the other hand, when capacitors C10 and C20 are connected in parallel, the overall capacitance of the AC generation circuit 42 is the sum of the individual capacitor capacitances, i.e., twice the capacitance. In other words, the overall capacitance of the AC generation circuit 42 differs by a factor of four depending on whether capacitors C10 and C20 are connected in series with the battery 30 or in parallel with the battery 30. Therefore, in the AC generating circuit 42, the frequency of the generated AC current differs by a factor of two when capacitors C10 and C20 are connected in series with the battery 30 and in parallel with the battery 30.

[0067] Here, in the AC generation circuit 42, the differences between the case where capacitors C10 and C20 are connected in series with the battery 30 and the case where they are connected in parallel with the battery 30 will be explained. Figure 3 This is an example of an equivalent circuit connected in series in the AC generating circuit 42 of the implementation method. Figure 4 This is an example of an equivalent circuit connected in parallel in the AC generating circuit 42 of the embodiment. Figure 3 The diagram shows an equivalent circuit in which capacitors C10 and C20 are connected in series with battery 30. Figure 4 The equivalent circuit is shown in the case where capacitors C10 and C20 are connected in parallel with battery 30. Figure 3 (a) and Figure 4 In (a), it is shown that in Figure 2 The equivalent circuit of the AC generating circuit 42 shown, where switches S11, S12, S21, and S22 are simply set to the on or off state, is... Figure 3 (b) and Figure 4 In (b), it is shown that it is easier to observe Figure 3 (a) or Figure 4The equivalent circuit shown in (a) is the equivalent circuit of the circuit. Furthermore, in Figure 3 In (c), the following is shown: Figure 3 The equivalent circuit shown in (b) is obtained by performing a Y-Δ transformation. Figure 3 and Figure 4 In this context, the inductive component of the inductance La of the battery 30 is designated as "Ls", and the resistive component of the resistance Ra is designated as "Rs". Furthermore, in... Figure 3 (a) and Figure 3 (b) and Figure 4 (a) and Figure 4 In (b), the capacitance of capacitors C10 and C20 is set to "Cx", the capacitance of capacitors C11 and C21 is set to "Cy", and the inductance of inductors L10 and L20 is set to "Lx". Furthermore, in Figure 3 In (c), the resistance components of impedances ZZ1 and ZZ4 are set to "Rx", the resistance components of impedances ZZ2 and ZZ5 are set to "Ry", and the resistance components of impedances ZZ3 and ZZ6 are set to "Rz".

[0068] The capacitance Cx of capacitors C10 and C20 is an example of the "first capacitor", and the capacitance Cy of capacitors C11 and C21 is an example of the "second capacitor".

[0069] like Figure 3 (a) and Figure 3 As shown in (b), in the AC generating circuit 42, when capacitors C10 and C20 are connected in series with the battery 30, capacitors C10 and C20 are connected in series via inductors L10 and L20. A capacitor C11 is inserted in series between capacitor C10 and the negative terminal of the battery 30, and a capacitor C21 is inserted in series between capacitor C20 and the positive terminal of the battery 30. In contrast, as... Figure 4 (a) and Figure 4As shown in (b), in the AC generating circuit 42, when capacitors C10 and C20 are connected in parallel with the battery 30, a parallel circuit of capacitor C11 and inductor L20 is inserted in series between capacitor C10 and the negative terminal of the battery 30, and a parallel circuit of capacitor C21 and inductor L10 is inserted in series between capacitor C20 and the positive terminal of the battery 30. Thus, in the AC generating circuit 42, by varying the connections of capacitors C11, C21, inductor L10, and inductor L20 between the series and parallel connections of capacitors C10 and C20, the frequency of the generated AC current can be made consistent in both the series and parallel connections. Furthermore, in the AC generating circuit 42, the current waveform of the generated AC current can be made closer to a sine wave in both the series and parallel connections of capacitors C10 and C20.

[0070] <Comparative Example>

[0071] [Structure of the AC generation circuit in the comparative example]

[0072] Here, in order to explain the effect of the structure of AC generating circuit 42, we will first describe a comparative example AC generating circuit (hereinafter referred to as "AC generating circuit 42C") that does not have capacitor C11, capacitor C21, inductor L10 and inductor L20. Figure 5 This is a diagram illustrating an example of the structure of the AC generating circuit 42C of the comparative example.

[0073] The AC generating circuit 42C includes, for example, capacitor C1, capacitor C2, switch S1, switch S2, and switch S3. Capacitor C1 and capacitor C2 are capacitors with equal electrostatic capacitance. Switches S1, S2, and S3, for example, control the connection or deconnection between their terminals according to the control signal CS output from the control unit 44. In the following description, the control signal output from the control unit 44 that controls switch S1 to be in a conducting or deconducting state is called "control signal CS1", the control signal output from the control unit 44 that controls switch S2 to be in a conducting or deconducting state is called "control signal CS2", and the control signal output from the control unit 44 that controls switch S3 to be in a conducting or deconducting state is called "control signal CS3".

[0074] The first terminal of capacitor C1 is connected to the positive terminal of battery 30. Additionally, the first terminal of capacitor C1 is connected to the first terminal of switch S2. The second terminal of capacitor C1 is connected to the first terminal of switch S1 and the second terminal of switch S3. The second terminal of capacitor C2 is connected to the negative terminal of battery 30. Additionally, the second terminal of capacitor C2 is connected to the second terminal of switch S1. The first terminal of capacitor C2 is connected to the second terminal of switch S2 and the first terminal of switch S3.

[0075] In AC generating circuit 42C, capacitor C1 is equivalent to capacitor C10 in AC generating circuit 42, and capacitor C2 is equivalent to capacitor C20 in AC generating circuit 42. In AC generating circuit 42C, switch S1 is equivalent to switch S21 in AC generating circuit 42, and switch S2 is equivalent to switch S11 in AC generating circuit 42. In AC generating circuit 42C, switch S3 is equivalent to switches S12 and S22 in AC generating circuit 42. Therefore, AC generating circuit 42C is a structure derived from AC generating circuit 42 by omitting capacitors C11 and C21, inductor L10, and inductor L20.

[0076] Figure 6 This is an example of the equivalent circuit of the comparative AC generating circuit 42C. Figure 6 In (a), an equivalent circuit is shown in which capacitors C1 and C2 are connected in series with the battery 30 in the AC generating circuit 42C. Figure 6 In (b), an equivalent circuit is shown where capacitors C1 and C2 are connected in parallel with battery 30 in AC generating circuit 42C. Figure 6 Nakaya and Figure 3 and Figure 4 Similarly, in the equivalent circuit of the AC generating circuit 42 shown, the inductive component of the inductance La of the battery 30 is set as "Ls", and the resistive component of the resistor Ra is set as "Rs". Furthermore, the capacitance of capacitors C1 and C2 is set as "Cx".

[0077] Here, refer to Figure 6 The frequency of the alternating current generated by the alternating current generating circuit 42C is explained. In the alternating current generating circuit 42C, as... Figure 6 As shown in (a), the impedance Z when capacitor C1 and capacitor C2 are connected in series can be obtained as shown in equation (1).

[0078] [Formula 1]

[0079]

[0080] Furthermore, the resonant frequency ωs in the AC generating circuit 42C, where capacitor C1 and capacitor C2 are connected in series, can be obtained as shown in equation (2).

[0081] [Formula 2]

[0082]

[0083] On the other hand, in the AC generation circuit 42C, such as Figure 6 As shown in (b), the impedance Z when capacitor C1 and capacitor C2 are connected in parallel can be obtained as shown in equation (3).

[0084] [Formula 3]

[0085]

[0086] Furthermore, the resonant frequency ωp in the AC generating circuit 42C, where capacitor C1 and capacitor C2 are connected in parallel, can be obtained as shown in equation (4).

[0087] [Formula 4]

[0088]

[0089] In the AC generating circuit 42C, if the resonant frequency ωs when capacitor C1 and capacitor C2 are connected in series and the resonant frequency ωp when capacitor C1 and capacitor C2 are connected in parallel are compared, the ratio becomes the ratio expressed by the following formula (5).

[0090] [Formula 5]

[0091] ωs∶ωp=2∶1…(5)

[0092] That is, in the AC generating circuit 42C, the resonant frequency ω differs depending on the difference in overall capacitance between the capacitors C1 and C2 connected in series and in parallel. More specifically, the resonant frequency ωs when capacitors C1 and C2 are connected in series is twice the resonant frequency ωp when they are connected in parallel. Therefore, in the AC generating circuit 42C, the current waveform of the generated AC current is not sinusoidal, but rather asymmetrical when the AC current is positive (plus) and negative (minus). Consequently, the generated AC current in the AC generating circuit 42C contains a large number of high-order harmonic components, which radiate a significant amount of noise when the battery 30 is heated.

[0093] Therefore, the efficiency of the AC generation circuit 42C decreases when the battery 30 in the vehicle 1 is composed of multiple batteries 30, for example, when the battery 30 is heated. For instance, when the battery 30 is composed of two batteries 30, it is considered to connect the AC generation circuit 42C to each battery 30 and impart a predetermined phase difference between the current waveforms of the AC current generated by each AC generation circuit 42C, thereby reducing the overall voltage fluctuation (so-called voltage waveform ripple) when the battery 30 is heated. That is, it is considered to reduce the overall voltage fluctuation when the battery 30 is heated by shifting the phase of the current waveform of the AC current generated by each AC generation circuit 42C by a predetermined phase between each AC generation circuit 42C. However, in the AC generation circuit 42C, the current waveform of the AC current is asymmetrical between positive and negative, therefore, it is not possible to sufficiently reduce the overall voltage fluctuation. Therefore, in the heating device (hereinafter referred to as "heating device 40C") that uses AC generation circuit 42C, the temperature of the battery 30 cannot be raised efficiently.

[0094] return Figure 3 and Figure 4 The frequency of the alternating current generated by the alternating current generating circuit 42 will be explained. First, consider... Figure 3 The resonant frequency ωs is shown when capacitor C10 and capacitor C20 are connected in series.

[0095] In the AC generation circuit 42, when capacitors C10 and C20 are connected in series, the impedance Zs can be determined according to... Figure 3 The equivalent circuit shown in (c) is obtained as shown in equation (6).

[0096] [Formula 6]

[0097]

[0098] According to equation (6) above, when applied to Figure 3 When the equivalent circuit shown in (b) is used, the impedance Zs in the AC generation circuit 42 with capacitor C10 and capacitor C20 connected in series can be expressed as shown in equation (7).

[0099] [Formula 7]

[0100]

[0101] That is, the impedance Zs can be obtained as shown in equation (8).

[0102] [Formula 8]

[0103]

[0104] Therefore, the resonant point of the AC current generated when capacitors C10 and C20 are connected in series in the AC generating circuit 42 is the point where the first term on the right side of the above equation (8) becomes zero. That is, the point where the impedance Zs is equal to the resistive component Rs of the resistance Ra of the battery 30 (as shown in the following equation (9)) is the resonant point of the AC current generated when capacitors C10 and C20 are connected in series in the AC generating circuit 42.

[0105] [Formula 9]

[0106] Zs=Rs…(9)

[0107] However, in order to satisfy the above equation (9), as shown in the following equation (10), the denominator of the first term on the right side of the above equation (8) must not be zero.

[0108] [Formula 10]

[0109]

[0110] Therefore, the numerator of the first term on the right side of the above equation (8) becomes zero, and the resonant frequency ω of the quadratic equation represented by the following equation (11) is the resonant frequency ωs when capacitor C10 and capacitor C20 are connected in series in the AC generating circuit 42.

[0111] [Formula 11]

[0112]

[0113] Therefore, the resonant frequency ωs in the AC generation circuit 42, where capacitor C10 and capacitor C20 are connected in series, can be represented by the following equation (12).

[0114] [Formula 12]

[0115]

[0116] At this time, if the condition of equation (13) is met, there are two possible resonant frequencies ωs when capacitors C10 and C20 are connected in series in AC generating circuit 42.

[0117] [Formula 13]

[0118]

[0119] However, when capacitor C10 and capacitor C20 are connected in series in AC generation circuit 42, the resonant frequency ωs becomes a certain value when the capacitance Cx of capacitor C10 and capacitor C20 is equal to the capacitance Cy of capacitor C11 and capacitor C21 (as shown in equation (14)).

[0120] [Formula 14]

[0121] Cx=Cy…(14)

[0122] More specifically, the impedance Zs is obtained as shown in equation (15) when the capacitors Cx and Cy are as shown in equation (14).

[0123] [Formula 15]

[0124]

[0125] In this case, the resonant point of the alternating current becomes the resonant frequency ωs of the above equation (9), which is represented by the following equation (16).

[0126] [Formula 16]

[0127]

[0128] Next, consider Figure 4 The resonant frequency ωp is shown when capacitor C10 and capacitor C20 are connected in parallel.

[0129] In the AC generation circuit 42, when capacitors C10 and C20 are connected in parallel, the impedance Zp can be determined according to... Figure 4 The equivalent circuit shown in (b) is obtained as shown in equation (17).

[0130] [Formula 17]

[0131]

[0132] That is, the impedance Zp can be obtained as shown in equation (18).

[0133] [Formula 18]

[0134]

[0135] Therefore, based on the same consideration as when capacitors C10 and C20 are connected in series, the resonant point of the AC current generated in the AC generating circuit 42 when capacitors C10 and C20 are connected in parallel is the point where the first term on the right side of the above equation (18) becomes zero. That is, the point where the impedance Zp is equal to the resistive component Rs of the resistance Ra of the battery 30 (as shown in equation (19)) is the resonant point of the AC current generated in the AC generating circuit 42 when capacitors C10 and C20 are connected in parallel.

[0136] [Formula 19]

[0137] Zp=Rs…(19)

[0138] However, in order to satisfy the above equation (19), similar to the case where capacitor C10 and capacitor C20 are connected in series, as shown in the following equation (20), the denominator of the first term on the right side of the above equation (18) must be non-zero.

[0139] [Formula 20]

[0140]

[0141] Therefore, the numerator of the first term on the right side of the above equation (18) becomes zero, and the resonant frequency ω of the quadratic equation expressed by the following equation (21) is the resonant frequency ωp when capacitor C10 and capacitor C20 are connected in parallel in the AC generating circuit 42.

[0142] [Formula 21]

[0143]

[0144] Therefore, the resonant frequency ωp in the AC generation circuit 42, where capacitor C10 and capacitor C20 are connected in parallel, can be represented by the following equation (22).

[0145] [Formula 22]

[0146]

[0147] At this time, if capacitor C10 and capacitor C20 are connected in parallel, and the condition of the following equation (23) is met, then there are two possible resonant frequencies ωp.

[0148] [Formula 23]

[0149]

[0150] In the AC generating circuit 42, when capacitors C10 and C20 are connected in parallel, even if the capacitance Cx of capacitors C10 and C20 is equal to the capacitance Cy of capacitors C11 and C21, there are two possible resonant frequencies ωp.

[0151] Therefore, in the AC generating circuit 42, in order to make the resonant frequency ωs of capacitor C10 and capacitor C20 connected in series equal to the resonant frequency ωp of capacitor C10 and capacitor C20 connected in parallel (as shown in equation (24)), it is only necessary for equation (25) to hold.

[0152] [Formula 24]

[0153] ωs=ωp…(24)

[0154] [Formula 25]

[0155]

[0156] Here, when the structural elements contained in the above equation (25) are replaced as in the following equation (26), the above equation (25) is expressed as in the following equation (27).

[0157] [Formula 26]

[0158]

[0159] [Formula 27]

[0160]

[0161] Then, when calculating the above equation (27), it becomes the following equation (28).

[0162] [Formula 28]

[0163]

[0164] When the substitution of equation (26) is substituted into equation (28), equation (25) is expressed as in equation (29).

[0165] [Formula 29]

[0166]

[0167] Then, when calculating the above equation (29), it becomes the following equation (30).

[0168] [Formula 30]

[0169]

[0170] Therefore, the relationship between the inductance Lx of inductors L10 and L20 in AC generation circuit 42, the inductance component Ls of inductor La in battery 30, the capacitance Cx of capacitors C10 and C20 in AC generation circuit 42, and the capacitance Cy of capacitors C11 and C21, is satisfied as long as the above equation (30) holds. That is, in AC generation circuit 42, in order for the resonant frequency ωs when capacitors C10 and C20 are connected in series to be equal to the resonant frequency ωp when capacitors C10 and C20 are connected in parallel (as in the above equation (24)), the above equation (30) is satisfied as long as it holds.

[0171] Here, as a condition for the AC generating circuit 42 to function as a circuit, in order for the inductance Lx of inductors L10 and L20 to be equal to the following equation (31), both the denominator and numerator on the right side of the above equation (30) need to be positive or both need to be negative. That is, the relationship between the capacitance Cy of capacitors C11 and C21 and the capacitance Cx of capacitors C10 and C20 needs to be equal to the following equation (32) or the following equation (33). In other words, when the relationship between the capacitance Cy of capacitors C11 and C21 and the capacitance Cx of capacitors C10 and C20 is equal to the following equation (34), the inductance Lx of inductors L10 and L20 will not be equal to the following equation (31). Therefore, in the AC generating circuit 42, the resonant frequency ωs when capacitors C10 and C20 are connected in series cannot be equal to the resonant frequency ωp (equation (24)) when capacitors C10 and C20 are connected in parallel.

[0172] [Formula 31]

[0173] Lx>0…(31)

[0174] [Formula 32]

[0175] Cy<2Cx…(32)

[0176] [Formula 33]

[0177] Cy>3Cx…(33)

[0178] [Formula 34]

[0179] 2Cx≤Cy≤3Cx…(34)

[0180] Here, we calculate the resonant frequency ωs, expressed by equation (12), when capacitors C10 and C20 are connected in series in the AC generating circuit 42. First, we replace the inductance Lx of inductors L10 and L20 within the square root of the numerator in equation (12) with equation (30), that is, we replace it with the following equation (35). Thus, the square root of the numerator in equation (12) becomes the following equation (36).

[0181] [Formula 35]

[0182]

[0183] [Formula 36]

[0184]

[0185] Then, when the numerator in the above equation (12) is expressed in terms of the above equation (36) and the calculation is performed, the above equation (12) is obtained as shown in the following equation (37).

[0186] [Formula 37]

[0187]

[0188] Therefore, in the case where capacitor C10 and capacitor C20 are connected in series in the AC generating circuit 42, the resonant frequency ωs is represented by two equations: the first resonant frequency ωs1 represented by equation (38) and the second resonant frequency ωs2 represented by equation (39).

[0189] [Formula 38]

[0190]

[0191] [Formula 39]

[0192]

[0193] Next, we calculate the resonant frequency ωp, expressed by equation (22), when capacitors C10 and C20 are connected in parallel in the AC generating circuit 42. Here, we first replace the inductance Lx of inductors L10 and L20 within the square root of the numerator in equation (22) with equation (30), i.e., equation (35). Thus, the square root of the numerator in equation (22) becomes equation (40).

[0194] [Formula 40]

[0195]

[0196] Then, when the numerator in the above equation (22) is expressed in terms of the above equation (40) and the calculation is performed, the above equation (22) is obtained as shown in the following equation (41).

[0197] [Formula 41]

[0198]

[0199] Therefore, in the AC generating circuit 42, when capacitor C10 and capacitor C20 are connected in parallel, the resonant frequency ωp is represented by two equations: the first resonant frequency ωp1 represented by equation (42) and the second resonant frequency ωp2 represented by equation (43).

[0200] [Formula 42]

[0201]

[0202] [Formula 43]

[0203]

[0204] Then, when observing the first resonant frequency ωp1 represented by the above equation (42) and the first resonant frequency ωs1 represented by the above equation (38), it can be seen that the resonant frequency ωs when capacitor C10 and capacitor C20 are connected in series is equal to the resonant frequency ωp when capacitor C10 and capacitor C20 are connected in parallel.

[0205] Here, the relationship between the first resonant frequency ω1 and the second resonant frequency ω2 will be explained. First, the relationship between the resonant frequency ωs1 expressed by equation (38) and the resonant frequency ωs2 expressed by equation (39) above will be explained when capacitor C10 and capacitor C20 are connected in series in the AC generating circuit 42.

[0206] Based on equations (38) and (39) above, the relationship between the resonant frequencies ωs1 and ωs2 can be expressed as shown in equation (44).

[0207] [Formula 44]

[0208]

[0209] Here, the left side of equation (44) above (equation (45) below) is always positive. Therefore, the relationship between the resonant frequencies ωs1 and ωs2 can be determined by the relationship between the capacitance Cx of capacitors C10 and C20 and the capacitance Cy of capacitors C11 and C21. More specifically, if the relationship between capacitance Cx and capacitance Cy is equation (46), then the relationship between the resonant frequencies ωs1 and ωs2 becomes equation (47). If the relationship between capacitance Cx and capacitance Cy is equation (48), then the relationship between the resonant frequencies ωs1 and ωs2 becomes equation (49).

[0210] [Formula 45]

[0211] 9Cx 2 -11CxCy+4Cy 2 …(45)

[0212] [Formula 46]

[0213] Cy>3Cx…(46)

[0214] [Formula 47]

[0215] ωsl<ωs2…(47)

[0216] [Formula 48]

[0217] Cy<2Cx…(48)

[0218] [Formula 49]

[0219] ωs1>ωs2…(49)

[0220] However, as described above, when capacitors C10 and C20 are connected in series in the AC generating circuit 42, when the capacitance Cx of capacitors C10 and C20 is equal to the capacitance Cy of capacitors C11 and C21 (as shown in equation (50)), there is no resonant frequency ωs1. That is, when capacitance Cx and capacitance Cy are equal, only one resonant frequency ωs2 is possible.

[0221] [Formula 50]

[0222] Cy=Cx…(50)

[0223] Next, the relationship between the resonant frequency ωp1 represented by the above equation (42) and the resonant frequency ωp2 represented by the above equation (43) will be explained when capacitor C10 and capacitor C20 are connected in parallel in the AC generation circuit 42.

[0224] Based on equations (42) and (43) above, the relationship between the resonant frequencies ωp1 and ωp2 can be expressed as shown in equation (51).

[0225] [Formula 51]

[0226]

[0227] Here, the left side of equation (51) above (equation (52) below) is always positive. Therefore, the relationship between the resonant frequencies ωp1 and ωp2 can also be determined by the relationship between the capacitance Cx of capacitors C10 and C20 and the capacitance Cy of capacitors C11 and C21. More specifically, if the relationship between capacitance Cx and capacitance Cy is equation (53), then the relationship between the resonant frequencies ωp1 and ωp2 becomes equation (54). If the relationship between capacitance Cx and capacitance Cy is equation (55), then the relationship between the resonant frequencies ωp1 and ωp2 becomes equation (56).

[0228] [Formula 52]

[0229] 9Cx 2 -5CxCy+Cy 2 …(52)

[0230] [Formula 53]

[0231] Cy>3Cx…(53)

[0232] [Formula 54]

[0233] ωp1<ωp2…(54)

[0234] [Formula 55]

[0235] Cy<2Cx…(55)

[0236] [Formula 56]

[0237] ωp1>ωp2…(56)

[0238] When the relationship between capacitances Cx and Cy, and the magnitudes of the first resonant frequency ω1 and the second resonant frequency ω2 are represented graphically, it becomes... Figure 7 . Figure 7 This is a diagram illustrating an example of the relationship between the capacitance (capacitance Cx and capacitance Cy) of the capacitors in the AC generation circuit 42 of the embodiment and the resonant frequencies (resonant frequencies ω1 and ω2).

[0239] exist Figure 7 As shown, within the first region A1 that satisfies equations (33), (46), and (53) above, the relationship between capacitance Cx and capacitance Cy is defined by equation (57). Two resonant frequencies ω exist, and the magnitudes of resonant frequencies ω1 and ω2 are related by equations (47) and (54). Furthermore, in Figure 7 As shown, within the second region A2, which is divided by the relationship between capacitance Cx and capacitance Cy by the following equation (58) and satisfies the above equations (32), (48), and (55), there exist two resonant frequencies ω. The magnitude relationship between resonant frequencies ω1 and ω2 is given by the above equations (49) and (56). Figure 7 As shown, within the second region A2, when the relationship between capacitor Cx and capacitor Cy is as stated in equation (50), the resonant frequency ω when capacitors C10 and C20 are connected in series, as described above, becomes only the resonant frequency ωs2. Furthermore, in Figure 7 As shown, in the third region A3 that satisfies the above equation (34), which is divided by the relationship between capacitors Cx and Cy by the following equations (57) and (58), there is no resonant frequency ω when capacitors C10 and C20 are connected in series with the storage battery 30 in the AC generating circuit 42 and when they are connected in parallel with the storage battery 30.

[0240] [Formula 57]

[0241] Cy=3Cx…(57)

[0242] [Formula 58]

[0243] Cy=2Cx…(58)

[0244] Thus, in the AC generation circuit 42, the relationship between capacitor Cx and capacitor Cy is: Figure 7In the first region A1 and the second region A2 shown, when capacitors C10 and C20 are connected in series with the battery 30 and in parallel with the battery 30 in the AC generating circuit 42, respectively, the resonant frequency ω of the generated AC current can be made equal.

[0245] However, when the battery 30 mounted on the vehicle 1 is heated by the heating device 40, the resonant frequency ωs becomes one when capacitors C10 and C20 are connected in series when capacitors Cx and Cy are equal. But it is assumed that the relationship between capacitors Cx and Cy is set as... Figure 7 The relationship within the second region A2 shown is more preferred. This is because, when the relationship between capacitor Cx and capacitor Cy is set as... Figure 7 When considering the relationship within the first region A1, whether capacitors C10 and C20 are connected in series with battery 30 or in parallel with battery 30, the resonant frequency ω1 on the side with the lower resonant frequency ω is equal. Furthermore, this is because, when the resonant frequency ω1 on the side with the lower resonant frequency ω is equal, the current waveform of the AC current generated by AC generating circuit 42 is affected by the higher and unequal resonant frequency ω2.

[0246] In the AC generating circuit 42, by adjusting (determining) the inductance Lx of inductors L10 and L20 in a manner that satisfies the relationship expressed by equation (59), AC currents with two resonant frequencies ω can be generated when capacitors C10 and C20 are connected in series and in parallel, respectively. More specifically, in the AC generating circuit 42, when capacitors C10 and C20 are connected in series, AC currents with two resonant frequencies ωs, expressed by equation (60), ωs1 and ωs2, can be generated; and when capacitors C10 and C20 are connected in parallel, AC currents with two resonant frequencies ωp, expressed by equation (61), ωp1 and ωp2, can be generated.

[0247] [Formula 59]

[0248]

[0249] [Formula 60]

[0250]

[0251] [Formula 61]

[0252]

[0253] Furthermore, in the AC generating circuit 42, for example, the resonant frequency ωs1 of the AC current generated when capacitor C10 and capacitor C20 are connected in series can be made equal to the resonant frequency ωp1 of the AC current generated when capacitor C10 and capacitor C20 are connected in parallel.

[0254] [An example of the resonant frequency of alternating current]

[0255] Here, an example of the resonant frequency ω of the alternating current generated by the alternating current generating circuit 42 will be explained. Figure 8 This is an example of an equivalent circuit used to illustrate the resonant frequency ω of the alternating current generated in the alternating current generation circuit 42 of the embodiment. Figure 8 The equivalent circuit is shown in the case where a predetermined AC voltage is supplied from AC power source E1 to AC generating circuit 42 instead of battery 30. Figure 8 In (a), an equivalent circuit is shown where capacitor C10 and capacitor C20 are connected in series. Figure 8 In (b), an equivalent circuit is shown in which capacitor C10 and capacitor C20 are connected in parallel.

[0256] Figure 9 This is a diagram illustrating an example of the frequency characteristics (analog characteristics) of the alternating current generated in the alternating current generation circuit 42 of the embodiment. Figure 9 Examples of frequency characteristics are shown in (a-1) to (a-3) when capacitor C10 and capacitor C20 are connected in series. Figure 9 Examples of frequency characteristics are shown in (b-1) to (b-3) when capacitor C10 and capacitor C20 are connected in parallel. Figure 9 (a-1) to (a-3) and Figure 9 In (b-1) to (b-3), the horizontal axis is the frequency, and the vertical axis is the gain of the generated alternating current.

[0257] Figure 9 An example of the frequency characteristics shown is in Figure 8 In the various equivalent circuits shown, the relationship between capacitor Cx and capacitor Cy is set as follows: Figure 7 The relationship within the second region A2 shown is an example where the resonant frequency ωs1 or ωp1 on the side with the higher resonant frequency ω of the generated alternating current is set to 200 kHz. Figure 9 As shown in, Figure 7In the second region A2 shown, the resonant frequency ωs is obtained when capacitors C10 and C20 are connected in series when capacitors Cx and Cy are equal. Therefore, by appropriately adjusting the inductance component Ls, inductance Lx, capacitor Cx and capacitor Cy based on the relationship expressed by the above equation (59), the resonant frequency ω1 can be ensured to be 200 kHz. Figure 9 (b-1) and Figure 9 (a-1) Figure 9 (b-2) and Figure 9 (a-2), and Figure 9 (b-3) and Figure 9 (a-3) represent the frequency characteristics when the inductance component Ls, inductance Lx, capacitance Cx, and capacitance Cy are the same.

[0258] like Figure 9 (a-1) and Figure 9 As shown in (b-1), it can be seen that there are two peak locations in both the case where capacitors C10 and C20 are connected in series and the case where they are connected in parallel. Therefore, there are two types of resonant frequencies ω. If, from this state, the capacitance Cy is set to a fixed value and the value of capacitance Cx is decreased until capacitance Cy equals capacitance Cx, as shown in (b-1),... Figure 9 As shown in (a-2), it can be seen that when capacitor C10 and capacitor C20 are connected in series, the peak position becomes a certain point, and the resonant frequency ω becomes a certain value. On the other hand, as... Figure 9 As shown in (b-2), it can be seen that when capacitors C10 and C20 are connected in parallel, the peak values ​​remain unchanged, and the resonant frequency ω still exists in two different forms. Furthermore, when capacitor Cy is set to a fixed value and capacitor Cx is decreased from this state to make Cy and Cx unequal, as shown in (b-2), the peak values ​​remain unchanged. Figure 9 (a-3) and Figure 9 As shown in (b-3), it can be seen that in both the case where capacitor C10 and capacitor C20 are connected in series and the case where they are connected in parallel, the peak value becomes two different locations, and the resonant frequency ω becomes two different types.

[0259] Thus, it can be seen that when capacitors C10 and C20 are connected in series in the AC generating circuit 42, the resonant frequency ωs is the same when the capacitances Cy and Cx are equal. However, the AC generating circuit 42 has four capacitors C: C10, C11, C20, and C21. Therefore, in a practical AC generating circuit 42, it is considered difficult to make the capacitances of the two capacitors C (C10 and C20) with capacitance Cx equal to the capacitances of the two capacitors C (C11 and C21) with capacitance Cy. This is because practical capacitors are components with a wide tolerance range even for capacitances within the same standard; that is, capacitors are components with large characteristic deviations. Therefore, it is considered that in a practical AC generating circuit 42, the case where the resonant frequency ωs is the same when capacitors C10 and C20 are connected in series is less likely.

[0260] In the AC generation circuit 42, for example, when the battery 30 installed in the vehicle 1 is a structure composed of multiple batteries 30, by connecting each battery 30 to the AC generation circuit 42 and imparting a predetermined phase difference between the current waveforms of the AC current generated by each AC generation circuit 42, it is possible to reduce the overall voltage fluctuation when the temperature of the battery 30 rises. That is, by shifting the phase of the current waveform of the AC current generated by each AC generation circuit 42 by a predetermined phase between each AC generation circuit 42, it is possible to reduce the overall voltage fluctuation when the temperature of the battery 30 rises. For example, when the battery 30 installed in the vehicle 1 is a structure composed of two batteries 30, by shifting the phase of the current waveform of the AC current generated by each AC generation circuit 42 connected to each battery 30 by 180°, it is possible to reduce the overall voltage fluctuation when the temperature of each battery 30 rises. For example, when the battery 30 installed in vehicle 1 is a structure consisting of three batteries 30, by shifting the phase of the current waveform of the alternating current generated by each alternating current generating circuit 42 connected to each battery 30 by 120°, it is possible to reduce the overall voltage fluctuation when the temperature of each battery 30 rises. This is because the current waveform of the alternating current generated by each alternating current generating circuit 42 is close to a symmetrical sine wave current waveform at both positive (plus) and negative (minus) current values. Therefore, the temperature of the battery 30 can be raised efficiently in the heating device 40.

[0261] [Operation of the heating device]

[0262] Next, an example of the operation of the heating device 40 will be explained. Here, the case where the battery 30 installed in vehicle 1 is a combination of two batteries 30 (battery 30a and battery 30b) will be described. In this case, each battery 30 is connected to an AC generating circuit 42, and the temperature is raised by applying (flowing) the generated AC current. At this time, the control unit 44 controls the phase of the AC current generated by each AC generating circuit 42 to be shifted by a predetermined phase (here, the phase is shifted by 180°), thereby reducing the overall voltage fluctuation (so-called voltage waveform ripple) output by the combination of the two batteries 30. In other words, the control unit 44 inputs the control signal CS to each AC generating circuit 42 in a manner that makes each AC generating circuit 42 operate in opposite directions, thereby reducing the overall voltage fluctuation when the temperature of the two batteries 30 is raised. Battery 30a is an example of a "first energy storage unit", and battery 30b is an example of a "second energy storage unit".

[0263] [Operation of the heating device in the comparative example]

[0264] First, in order to compare with the operation of the heating device 40, the following was observed: Figure 5 The operation of the heating device (heating device 40C) of the AC generating circuit 42C shown in the comparative example will be explained. Figure 10 This is a diagram showing an example of the operating waveform (analog waveform) of the heating device 40C using the AC generating circuit 42C of the comparative example. Figure 10 This is an example where the resonant frequency ω of the AC current generated by the AC generating circuit 42C is set to 200 kHz.

[0265] exist Figure 10 In (a), the connections of the AC generating circuits 42C (AC generating circuits 42Ca and 42Cb) corresponding to each battery 30 are shown, as well as the AC current flowing within each AC generating circuit 42C. Figure 10 In (b), an example is shown of the control signals output by the control unit 44 to each switch, the alternating current in each alternating current generating circuit 42C, and the change in output voltage. Figure 10 In the diagram, the "a" at the end of each label indicates that it corresponds to AC generation circuit 42Ca, and the "b" indicates that it corresponds to AC generation circuit 42Cb.

[0266] like Figure 10As shown in (a), in the case of a structure consisting of two batteries 30, one battery 30a is connected to an AC generating circuit 42Ca, and the other battery 30b is connected to an AC generating circuit 42Cb. Furthermore, the control unit 44 outputs switching control signals to the switches of each AC generating circuit 42C in such a way that the phase of the AC current generated by each AC generating circuit 42C is offset by 180°. Figure 10 In (a), an example is shown of the measurement position and current flow direction of the voltage that changes in each AC generating circuit 42C due to the control unit 44 controlling each switch with a control signal. More specifically, as an example of voltage and current corresponding to AC generating circuit 42C, the voltages V1-V0 between the terminals of battery 30a (including inductor Laa), the currents I-C1a flowing in capacitor C1a and C2a, and the current I-E1a flowing in battery 30a (including inductor Laa) are shown respectively. Furthermore, as an example of voltage and current corresponding to AC generating circuit 42Cb, the voltages V2-V1 between the terminals of battery 30b (including inductor Lab), the currents I-C1b flowing in capacitor C1b and C2b, and the current I-E1b flowing in battery 30b (including inductor Lab) are shown respectively. Moreover, in Figure 10 In (a), the voltage V2-V0 is shown as the voltage of the entire combination of batteries 30a and 30b, which is the voltage between the negative terminal (V0) of battery 30a in AC generation circuit 42Ca and the positive terminal (V2) of battery 30b in AC generation circuit 42Cb.

[0267] exist Figure 10 In (b), an example is shown where the control unit 44 controls the various control signals CS of each AC generating circuit 42C, as well as the changes in current and voltage in AC generating circuits 42Ca and 42Cb. Figure 10 In (b), the control unit 44 sets each control signal CS to a "high" level to turn on the corresponding switch, and sets each control signal CS to a "low" level to turn on the corresponding switch. In the AC generation circuit 42C, as described above, the resonant frequency ωs when capacitor C1 and capacitor C2 are connected in series is twice the resonant frequency ωp when capacitor C1 and capacitor C2 are connected in parallel. Therefore, in Figure 10 In (b), the control unit 44 outputs control signals CS to each switch with a duty cycle of 1:2.

[0268] exist Figure 10In (b), an example is shown where the voltage V1-V0, current I-C1a, current I-C2a, and current I-E1a vary due to the control signals CS1a, CS2a, and CS3a controlled by the control unit 44 to the AC generating circuit 42Ca. Furthermore, in Figure 10 In (b), an example is shown where the voltage V2-V1, current I-C1b, current I-C2b, and current I-E1b change due to the control signals CS1b, CS2b, and CS3b controlled by the control unit 44 to the AC generating circuit 42Cb. Furthermore, in Figure 10 (b) shows an example of the change in voltage V2-V0.

[0269] like Figure 10 As shown in (b), during period PSa, the control unit 44 sets the control signals CS1a and CS2a of the AC generating circuit 42Ca to a "low" level and the control signal CS3a to a "high" level. Consequently, in the AC generating circuit 42Ca, capacitors C1a and C2a are connected in series with the battery 30a, and currents I-C1a and I-C2a flow to the positive region, thus current I-E1a also flows to the positive region. As a result, the voltage V1-V0 of the AC generating circuit 42Ca decreases from a positive peak voltage to a negative peak voltage. On the other hand, during period PPa, the control unit 44 sets the control signals CS1a and CS2a of the AC generating circuit 42Ca to a "high" level and the control signal CS3a to a "low" level. Therefore, in the AC generating circuit 42Ca, capacitors C1a and C2a are connected in parallel with the battery 30a, and currents I-C1a and I-C2a flow into the negative region. Consequently, current I-E1a also flows into the negative region. As a result, the voltage V1-V0 of the AC generating circuit 42Ca rises from a negative peak voltage to a positive peak voltage.

[0270] like Figure 10As shown in (b), in the AC generating circuit 42Cb, the control unit 44 also controls the control signals CS1b, CS2b, and CS3b during periods PSb and PPb. Therefore, in the AC generating circuit 42Cb, currents I-C1b and I-C2b flow in the same manner as in the AC generating circuit 42Ca, and current I-E1b also flows. However, as described above, the control unit 44 outputs each control signal CS with a phase shift of 180° between the phase of the AC current generated by each AC generating circuit 42Cb and the phase of I-C2b and I-E1b flowing in the AC generating circuit 42Cb. Therefore, the phase of the currents I-C1b, I-C2b, and I-E1b flowing in the AC generating circuit 42Cb is shifted by 180° compared to the phase of the currents I-C1a, I-C2a, and I-E1a flowing in the AC generating circuit 42Ca. As a result, the phase of the voltage V2-V1 of the AC generating circuit 42Cb is shifted by 180° compared to the phase of the voltage V1-V0 of the AC generating circuit 42Ca.

[0271] Thus, in the heating device 40C, the control unit 44 outputs control signals CS to each switch with a duty cycle of 1:2, such as... Figure 10 As shown in (b), the voltage V2-V0 is the voltage obtained by adding the voltage V1-V0 of the AC generating circuit 42Ca and the voltage V2-V1 of the AC generating circuit 42Cb. However, according to Figure 10 As can be seen from the waveform of voltage V2-V0 shown in (b), although the amplitude is narrower than that of voltage V1-V0 and voltage V2-V1, the voltage waveform is not close to a sine wave. This is because the control unit 44 switches the connection of capacitors C1 and C2 to the battery 30 in series or parallel connection with a duty cycle of 1:2. Therefore, the current waveforms of the AC currents (currents I-E1a and I-E1b) generated by each AC generating circuit 42C are not sine waves, and the amplitudes are different in the positive and negative regions of the AC current, that is, they are asymmetrical in the positive and negative regions.

[0272] Next, the operation of the heating device 40 will be explained. Figure 11 This is a diagram showing an example of the operating waveform (analog waveform) of the heating device 40 employing the AC generating circuit 42 of the embodiment. Figure 11 The relationship between the capacitance Cx of capacitors C10 and C20 and the capacitance Cy of capacitors C11 and C21 is given by the following equation (62), and is related to... Figure 10 The example shown is an example of the operating waveform of the AC generating circuit 42C in the comparative example. Similarly, it is an example where the resonant frequency ω of the AC current generated by the AC generating circuit 42 is set to 200 [kHz].

[0273] [Formula 62]

[0274] Cy<Cx…(62)

[0275] exist Figure 11 In (a), the connections of the AC generating circuits 42 (AC generating circuits 42a and 42b) corresponding to each battery 30 are shown, as well as the AC current flowing within each AC generating circuit 42. Figure 11 In (b), an example is shown of the control signals output by the control unit 44 to each switch, the alternating current in each alternating current generating circuit 42, and the change in output voltage. Figure 11 In the diagram, the "a" at the end of each designation indicates AC generating circuit 42a, and "b" indicates AC generating circuit 42b. AC generating circuit 42a is an example of an "AC generating circuit," and AC generating circuit 42b is an example of a "second AC generating circuit." The AC current generated by AC generating circuit 42a is an example of "AC current," and the AC current generated by AC generating circuit 42b is an example of "second AC current."

[0276] like Figure 11 As shown in (a), in the case of a structure consisting of two batteries 30, one battery 30a is connected to an AC generating circuit 42a, and the other battery 30b is connected to an AC generating circuit 42b. Furthermore, the control unit 44 outputs control signals to the switches of each AC generating circuit 42 in such a way that the phase of the AC current generated by each AC generating circuit 42 is offset by 180°. Figure 11 In (a), an example is shown of the measurement position of the voltage changing in each AC generating circuit 42, and the direction of current flow, which is controlled by the control unit 44 using control signals. More specifically, as an example of voltage and current corresponding to AC generating circuit 42a, the voltages V1-V0 between the terminals of the battery 30a (including inductor Laa), the currents I-C10a flowing in capacitor C10a and C20a, and the current I-E1a flowing in battery 30a (including inductor Laa) are shown. Furthermore, as an example of voltage and current corresponding to AC generating circuit 42b, the voltages V2-V1 between the terminals of the battery 30b (including inductor Lab), the currents I-C10b flowing in capacitor C10b and C20b, and the current I-E1b flowing in battery 30b (including inductor Lab) are shown. Moreover, in Figure 11In (a), the voltage V2-V0 is shown as the voltage of the entire combination of batteries 30a and 30b, which is the voltage across one end (V0) of the negative terminal of battery 30a in AC generation circuit 42a and one end (V2) of the positive terminal of battery 30b in AC generation circuit 42b.

[0277] exist Figure 11 In (b), an example is shown where the control unit 44 controls the various control signals CS of each AC generating circuit 42, as well as the changes in current and voltage in AC generating circuits 42a and 42b. Figure 11 In (b), the control unit 44 sets each control signal CS to a "high" level to turn on the corresponding switch, and sets each control signal CS to a "low" level to turn on the corresponding switch. In the AC generation circuit 42, as described above, the resonant frequency ωs when capacitors C10 and C20 are connected in series is equal to the resonant frequency ωp when capacitors C10 and C20 are connected in parallel. Therefore, in Figure 11 In (b), the control unit 44 sets the duty cycle to 50% and outputs a control signal CS to each switch. As described above, the control unit 44 can also set a dead time to set all switches to the non-conducting state between the period when the switches are set to the on state and the period when the switches are set to the non-conducting state. Figure 11 In (a), the control unit 44 is shown controlling each switch with a dead time. However, in the following description, for ease of explanation, detailed explanations related to the dead time will be omitted. That is, the description will be based on a control unit 44 that is equivalent to the case where each switch is controlled without a dead time.

[0278] exist Figure 11 In (b), an example is shown where the voltage V1-V0, current I-C10a, current I-C20a, and current I-E1a vary due to the control signals CS11a, CS21a, CS12a, and CS22a controlled by the control unit 44 to the AC generating circuit 42a. Furthermore, in Figure 11 In (b), an example is shown where the voltage V2-V1, current I-C10b, current I-C20b, and current I-E1b vary due to the control signals CS11b, CS21b, CS12b, and CS22b controlled by the control unit 44 to the AC generating circuit 42b. Furthermore, in Figure 11 Example of the change in voltage V2-V0 is also shown in (b).

[0279] like Figure 11As shown in (b), during period P1, the control unit 44 sets the control signals CS11a and CS21a of the AC generating circuit 42a to a "low" level and the control signals CS12a and CS22a to a "high" level. Consequently, in the AC generating circuit 42a, capacitors C10a and C20a are connected in series with the battery 30a, and currents I-C10a and I-C20a flow from the negative region to the positive region, thus current I-E1a mainly flows to the negative region. Consequently, the voltages V1-V0 of the AC generating circuit 42a rise from negative peak voltages to positive peak voltages. On the other hand, during period P1, the control unit 44 sets the control signals CS11b and CS21b of the AC generating circuit 42b to a "high" level and the control signals CS12b and CS22b to a "low" level. Therefore, in the AC generating circuit 42b, capacitors C10b and C20b are connected in parallel with the battery 30a. Currents I-C10b and I-C20b mainly flow into the positive region, and consequently, current I-E1b also mainly flows into the positive region. As a result, the voltage V2-V1 of the AC generating circuit 42b decreases from a positive peak voltage towards a negative peak voltage.

[0280] After that, as Figure 11 As shown in (b), during period P2, the control unit 44 sets the control signals CS11a and CS21a of the AC generating circuit 42a to a "high" level and the control signals CS12a and CS22a to a "low" level. Consequently, in the AC generating circuit 42a, capacitors C10a and C20a are connected in parallel with the battery 30a, and currents I-C10a and I-C20a flow primarily to the positive region, thus current I-E1a also flows primarily to the positive region. As a result, the voltages V1-V0 of the AC generating circuit 42a decrease from positive peak voltages towards negative peak voltages. On the other hand, during period P2, the control unit 44 sets the control signals CS11b and CS21b of the AC generating circuit 42b to a "low" level and the control signals CS12b and CS22b to a "high" level. Therefore, in the AC generating circuit 42b, capacitors C10b and C20b are connected in series with the battery 30a. Currents I-C10b and I-C20b flow from the negative region to the positive region, and thus, current I-E1b mainly flows to the negative region. Consequently, the voltage V2-V1 of the AC generating circuit 42b rises from a negative peak voltage to a positive peak voltage.

[0281] In this way, the control unit 44 outputs each control signal CS with the phase of the AC current generated by each AC generating circuit 42 shifted by 180°, as described above. Consequently, the phases of the currents I-C10a, I-C20a, and I-E1a flowing in AC generating circuit 42a are shifted by 180° compared to the phases of the currents I-C10b, I-C20b, and I-E1b flowing in AC generating circuit 42b. Consequently, the phases of the voltages V1-V0 in AC generating circuit 42a are also shifted by 180° compared to the phases of the voltages V2-V1 in AC generating circuit 42b.

[0282] Thus, in the heating device 40, the control unit 44 outputs a control signal CS to each switch, setting the duty cycle to 50%, switching the connection between capacitors C10 and C20 and the battery 30 to either a series connection or a parallel connection. Therefore, as... Figure 11 As shown in (b), the voltage V2-V0 is the voltage obtained by adding the voltage V1-V0 of the AC generating circuit 42a to the voltage V2-V1 of the AC generating circuit 42b. Furthermore, according to... Figure 11 As can be seen from the voltage waveform V2-V0 shown in (a), this voltage waveform is similar to... Figure 10 Compared to the voltage waveforms of V2-V0 in the heating device 40C shown, the voltage fluctuations (so-called voltage waveform ripple) are less. This is because the current waveforms of the AC currents (currents I-E1a and I-E1b) generated by the various AC generating circuits 42 in the heating device 40 are less pronounced than those in the heating device 40C. Figure 10 Compared to the current waveforms of the alternating currents (current I-E1a, current I-E1b) generated by each alternating current generating circuit 42 in the heating device 40C shown, the waveforms are closer to sine waves.

[0283] [Another function of the heating device]

[0284] Figure 12 This is another example of the operating waveform (analog waveform) of the heating device 40 using the AC generating circuit 42 of the embodiment. Figure 12 (a) is in Figure 11 In the structure shown in (a), an example is given where the relationship between capacitor Cx and capacitor Cy is set as follows (63). Figure 12 (b) is in Figure 11 This is an example of a structure shown in (a) where the relationship between capacitor Cx and capacitor Cy is set as follows (64). Figure 12 Nakaya and Figure 11 Similarly, in the example shown, the resonant frequency ω of the AC current generated by the AC generating circuit 42 is set to 200 kHz. Therefore, in Figure 12In one example shown, the inductance component Ls, inductance Lx, capacitance Cx and capacitance Cy are appropriately adjusted based on the relationship expressed by equation (59) above to ensure that the resonant frequency ω1 is 200 kHz.

[0285] [Formula 63]

[0286] Cy=Cx…(63)

[0287] [Formula 64]

[0288] Cy>Cx…(64)

[0289] exist Figure 12 In one example shown, it is also related to Figure 11 Similarly, in the example shown, control unit 44 sets the duty cycle to 50% and outputs control signal CS to each switch. (Comparison) Figure 11 The example shown in (b) is similar to Figure 12 (a) and Figure 12 As shown in example (b), although the amplitudes of voltages V1-V0, V2-V1, currents I-C10a, I-C20a, I-C10b, I-C20b, I-E1a, and I-E1b are different, their changes are the same. Therefore, Figure 12 (a) and Figure 12 In the example shown in (b), the control unit 44's control over the AC generating circuit 42 and the operation of each AC generating circuit 42 can be considered as using Figure 11 The control unit 44 described herein controls the AC generating circuit 42, and the operation of each AC generating circuit 42 is the same. Therefore, [details omitted]. Figure 12 (a) and Figure 12 The example shown in (b) provides a detailed description of the control unit 44's control over the AC generating circuit 42 and the operation of each AC generating circuit 42.

[0290] Thus, in the heating device 40, when the battery 30 installed in the vehicle 1 is a combination of two batteries 30 (here, battery 30a and battery 30b), the control unit 44 outputs a control signal CS to each switch, setting the duty cycle to 50%, switching the connection of capacitors C10 and C20 with the battery 30 to either a series connection or a parallel connection. In other words, the control unit 44 controls the output so that the phase of the control signal CS is shifted by a predetermined phase (here, a phase shift of 180°) in a manner opposite to the operation of the AC generating circuit 42 corresponding to each battery 30. Therefore, as... Figure 11 (b) Figure 12 (a) and Figure 12As shown in (b), the AC generation circuit 42 can reduce the voltage fluctuations V2-V0 of the combined battery 30. In other words, the AC generation circuit 42 can generate an AC current with reduced high-order harmonic components, thereby reducing the noise radiated when the battery 30 is heated. Therefore, when the battery 30 in the vehicle 1 is a combination of two batteries, the AC generation circuit 42 is more easily applied as a structure that raises the temperature by applying (flowing) AC current to each battery 30 and reduces the voltage fluctuations (so-called voltage waveform ripple) of the combined output voltage of the two batteries 30.

[0291] As described above, the heating device 40 according to the embodiment includes capacitors C10, C11, C20, and C21, switches S11, S12, S21, and S22, inductor L10, and inductor L20 in the AC generation circuit 42. Furthermore, in the heating device 40 of this embodiment, by switching the connection between capacitors C10 and C20 in the AC generation circuit 42 and the battery 30 to a series connection or a parallel connection, an AC current based on the power stored in the battery 30 is generated using a resonant operation. This resonant operation is an operation that alternately exchanges the magnetic energy stored in the inductor La of the battery 30 with the electrostatic energy stored in at least capacitor C10. At this time, in the AC generating circuit 42 of the embodiment, the overall impedance of the AC generating circuit 42 is adjusted to be the same through the various structural elements of capacitor C11, capacitor C21, inductor L10, and inductor L20. When capacitors C10 and C20 are connected in series with the battery 30 and in parallel with the battery 30, AC currents with the same resonant frequency ω are generated. Therefore, in the heating device 40 of the embodiment, the current waveform of the AC current generated by each AC generating circuit 42 becomes a current waveform closer to a sine wave. Therefore, in the heating device 40 of the embodiment, the battery 30 can be heated more efficiently using the AC current with a near-sine wave current waveform generated by the AC generating circuit 42. Therefore, in the vehicle 1 using the heating device 40 of the embodiment, the battery 30 can be used while being heated to a suitable temperature, and the degradation of the charging and discharging performance of the battery 30 can be suppressed. Furthermore, in the vehicle 1 that employs the heating device 40 of the embodiment, the alternating current generated by the alternating current generating circuit 42 contains fewer high-order harmonic components, thus reducing the noise radiated when the battery 30 is heated.

[0292] However, in the heating device 40 of the above-described embodiment, it is explained that the capacitances Cx of capacitors C10 and C20 in the AC generating circuit 42 are equal, the capacitances Cy of capacitors C11 and C21 are equal, and the inductances Lx of inductors L10 and L20 are equal. Furthermore, it is explained that the inductance component of the inductance La of the battery 30 is denoted as inductance component Ls, and the capacitance or inductance of each structural element is adjusted (determined) based on the relationship expressed by the above equation (59). However, it is assumed that even for identical components, the characteristics of the capacitance or inductance of each structural element may differ. Furthermore, it is also assumed that the wiring portion connecting the AC generating circuit 42 and the battery 30 also includes an inductance component. Therefore, in the heating device 40 of the embodiment, the capacitance or inductance of each structural element of the AC generating circuit 42 can be set to take into account the deviation of the characteristics of each structural element, the deviation of the inductance component Ls of the inductance La of the battery 30, and the value of the inductance component contained in the wiring portion connecting the AC generating circuit 42 and the battery 30. That is, in the heating device 40 of the embodiment, if the current waveform of the AC current generated by the AC generating circuit 42 can be considered to be a sine wave (the range in which a substantial effect is obtained), then the values ​​of the capacitance Cx of capacitors C10 and C20, the capacitance Cy of capacitors C11 and C21, and the inductance Lx of inductors L10 and L20 can also have a certain degree of amplitude. In other words, in the heating device 40 of the embodiment, any value within the range that can be said to be equal to the capacitance Cx of capacitors C10 and C20, equal to the capacitance Cy of capacitors C11 and C21, and equal to the inductance Lx of inductors L10 and L20 is acceptable.

[0293] In the heating device 40 of the above embodiment, the case where the duty cycle of the control signal CS output by the control unit 44 to each switch is 50% is described. However, as described above, the control unit 44 may also control the switches by setting a dead time between the period when the switch is set to the on state and the period when the switch is set to the off state, thus setting all switches to the off state. For example, in the heating device 40 of the embodiment, the control unit 44 may also set a dead time by setting the duty cycle of the control signal CS output to each switch to a value that can be considered approximately 50% (for example, a specified value between 45% and 55%), and output the control signal CS to each switch, thereby switching the connection between capacitor C10 and capacitor C20 and battery 30 from parallel connection to series connection, or from series connection to parallel connection.

[0294] The heating device 40 according to the above-described embodiment includes, in an AC generating circuit 42 that heats the battery 30 by generating an AC current based on the power stored in the battery 30 having an inductance La, the following components are included: a capacitor C10, the first terminal of which is connected to the positive terminal of the battery 30; a capacitor C11, the first terminal of which is connected to the second terminal of the capacitor C10, and the second terminal of which is connected to the negative terminal of the battery 30; a capacitor C20, the second terminal of which is connected to the negative terminal of the battery 30; a capacitor C21, the second terminal of which is connected to the first terminal of the capacitor C20, and the first terminal of which is connected to the positive terminal of the battery 30; and a switch S11, the first terminal of which is connected to the capacitor C10. The first terminal of switch S11 is connected to the second terminal of switch S11, and the second terminal is connected to the second terminal of capacitor C10; switch S21 is connected to the second terminal of capacitor C20; switch S22 is connected to the first terminal of switch S21, and the first terminal is connected to the first terminal of capacitor C20; inductor L10 is connected between the second terminal of switch S11 and the first terminal of switch S22; and inductor L20 is connected between the second terminal of switch S12 and the first terminal of switch S21. This allows the battery 30 used in vehicle 1 to be heated more efficiently. Therefore, in vehicle 1 equipped with the heating device 40 of this embodiment, the battery 30 can be used at a suitable temperature, suppressing the decline in the charging and discharging performance of the battery 30. Thus, in vehicle 1 equipped with the heating device 40 of this embodiment, the durability and other commercial properties of vehicle 1 can be improved. Therefore, in the vehicle 1 equipped with the heating device 40 of the embodiment, energy efficiency is improved, and it is expected to contribute to mitigating the adverse effects on the Earth's environment.

[0295] In the various embodiments described above, a structure was described in which the control device 100 controls the start or stop of the heating device 40, and the control unit 44 controls the switches provided in the AC generation circuit 42 to be in an on or off state. The operation of the control unit 44 can also be implemented by executing a program through a hardware processor such as a CPU provided in the control unit 44. The function of the control device 100 may also include the function of the control unit 44 described above. In this case, the control unit 44 may be omitted in the heating device 40.

[0296] The present invention has been described above using embodiments, but the present invention is not limited to such embodiments and can be modified and replaced in various ways without departing from the spirit of the present invention.

Claims

1. An AC generating circuit that heats the energy storage medium by generating an AC current based on the electrical power stored in the medium having an inductive component, wherein, The AC generating circuit includes: A first capacitor, the first end of which is connected to the positive terminal side of the energy storage body; A second capacitor, the first end of which is connected to the second end of the first capacitor, and the second end of which is connected to the negative terminal side of the energy storage body; A third capacitor, the second end of which is connected to the negative electrode side of the energy storage body; A fourth capacitor, the second end of which is connected to the first end of the third capacitor, and the first end of which is connected to the positive electrode side of the energy storage body; A first switch, wherein the first terminal of the first switch is connected to the first terminal of the first capacitor; A second switch, wherein the first terminal of the second switch is connected to the second terminal of the first switch, and the second terminal of the second switch is connected to the second terminal of the first capacitor; A third switch, the second terminal of which is connected to the second terminal of the third capacitor; A fourth switch, the second terminal of which is connected to the first terminal of the third switch, and the first terminal of the fourth switch is connected to the first terminal of the third capacitor; A first inductor is connected between the second terminal of the first switch and the first terminal of the fourth switch; as well as A second inductor is connected between the second terminal of the second switch and the first terminal of the third switch. The inductance of the first inductor, the inductance of the second inductor, the capacitance of the first capacitor, the capacitance of the second capacitor, the capacitance of the third capacitor, and the capacitance of the fourth capacitor are adjusted based on a relationship that includes the inductance component, so that the current waveform of the alternating current approximates a sine wave. The first switch and the third switch are controlled to be in a conducting state or a non-conducting state according to the first control signal. The second switch and the fourth switch are controlled to be in a conducting state or a non-conducting state according to the second control signal. The periods during which the first control signal turns on the first switch and the third switch, and the periods during which the second control signal turns on the second switch and the fourth switch, are non-overlapping periods.

2. The AC generating circuit according to claim 1, wherein, The inductance of the first inductor and the inductance of the second inductor are equal.

3. The AC generating circuit according to claim 2, wherein, The capacitance of the first capacitor and the capacitance of the third capacitor are equal to the capacitance of the first capacitor.

4. The AC generating circuit according to claim 3, wherein, The capacitance of the second capacitor and the capacitance of the fourth capacitor are equal.

5. The AC generating circuit according to claim 4, wherein, The second capacitor is smaller than twice the capacitance of the first capacitor.

6. The AC generating circuit according to claim 4, wherein, The second capacitor is a capacitor that is three times larger than the first capacitor.

7. The AC generating circuit according to claim 4, wherein, The second capacitor and the first capacitor are equal in capacitance.

8. The AC generating circuit according to claim 1, wherein, The inductive component includes the inductive component present in the wiring portion between the energy storage body and the AC generating circuit.

9. The AC generating circuit according to any one of claims 1 to 8, wherein, The energy storage device includes a first energy storage device and a second energy storage device connected in series with the first energy storage device. The AC generating circuit is connected to the first energy storage device. A second AC generating circuit, with the same structure as the AC generating circuit, is connected to the second energy storage device. The first control signal and the second control signal are input in such a way that a predetermined phase difference is given between the AC current generated by the AC generating circuit and the AC current generated by the second AC generating circuit, i.e., the second AC current.

10. A heating device, wherein, The heating device includes: The AC generating circuit as described in claim 9; and The control unit outputs the first control signal and the second control signal, and alternately switches between the first state and the second state through the first control signal and the second control signal. In the first state, the first switch and the third switch are set to the non-conducting state, and the second switch and the fourth switch are set to the conducting state. In the second state, the first switch and the third switch are set to the conducting state, and the second switch and the fourth switch are set to the non-conducting state.

Images