Battery charging device

Abstract

This battery charging device comprises: an electric power generator that generates electric power in accordance with rotation of a rotor and outputs an AC signal that corresponds to the generated electric power; a switching element that rectifies the AC signal outputted by the electric power generator and supplies the rectified AC signal to the battery as charging electric power; a diode that supplies movement electric power to a load unit, the diode being connected between the load unit and an output line of the switching element; a capacitor that is connected to an output line of the diode and is connected in parallel to the load unit; a voltage control unit that controls conduction to the switching element such that the voltage supplied to the load unit becomes an output-target set voltage; and a switching control unit that reduces the set voltage when the battery enters an abnormal state in which the battery cannot be used.

Description

[Technical Field]

[0001] The present invention relates to a battery charging device. This application claims priority based on Japanese Patent Application No. 2022-126531, filed on August 8, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] In recent years, battery charging devices that charge batteries using the rotation of an internal combustion engine of a motorcycle or the like have become known (see, for example, Patent Document 1). In such conventional battery charging devices, the AC signal output by a generator is half-wave rectified using a switching element such as a thyristor to charge the battery and also supply power to a load via a diode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 132440 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in recent years, for example, in motorcycles, the load connected to the generator and battery has increased due to an increase in electronic control by FI (Fuel Injection: Electronically Controlled Fuel Injection Device) and an increase in sensors, etc. However, with the above-mentioned conventional battery charging device, for example, when the battery is disconnected, the ripple current of the current supplied to the load section increases, which poses a problem in that it becomes necessary to increase the capacity of the capacitor connected in parallel to the load section.

[0005] The present invention has been made to solve the above problems, and its purpose is to provide a battery charging device that can reduce the ripple current of the current supplied to the load section without increasing the capacity of the capacitor connected in parallel to the load section. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the present invention is a battery charging device comprising: a generator that generates electricity in accordance with the rotation of a rotor and outputs an AC signal in accordance with the generated power; a switching element that rectifies the AC signal output by the generator and supplies it to a battery as charging power; a diode connected between the output line of the switching element and a load section and supplies operating power to the load section; a capacitor connected to the output line of the diode and connected in parallel with the load section; a voltage control section that controls the conduction of the switching element so that the voltage supplied to the load section becomes a set output target voltage; and a switching control section that lowers the set voltage when the battery enters an abnormal state that makes it unusable.

[0007] In addition, one aspect of the present invention is that in the above-mentioned battery charging device, the switching control unit may determine that the abnormal state exists when the voltage of the output line of the diode is greater than the voltage of the output line of the switching element during a period when the switching element is in a non-conducting state.

[0008] In addition, in one aspect of the present invention, in the battery charging device, the switching control unit may determine whether or not the abnormal state occurs during a period in which the AC signal is at a negative voltage.

[0009] In addition, one aspect of the present invention is that in the above-mentioned battery charging device, the switching control unit sets the set voltage to a first set voltage for charging the battery in a normal state in which the battery is usable, and in the abnormal state, switches the set voltage to a second set voltage that is lower than the first set voltage and that allows the load unit to operate.

[0010] In addition, one aspect of the present invention is that in the above-mentioned battery charging device, the switching element is a thyristor, and the voltage control unit controls the conduction timing of the switching element so that the voltage supplied to the load unit becomes the set voltage.

[0011] In addition, according to one aspect of the present invention, in the battery charging device, the abnormal state may include a state in which the battery is disconnected from the device itself. [Effects of the Invention]

[0012] According to the present invention, the voltage control unit controls the conduction of the switching element so that the voltage supplied to the load unit becomes the output target set voltage, and the switching control unit lowers the set voltage when the battery enters an abnormal state where it is unusable. As a result, the battery charging device can reduce the ripple current of the current supplied to the load unit when the battery enters an abnormal state where it is unusable, and there is no need to increase the capacitance of the capacitor. In other words, the battery charging device can reduce the ripple current of the current supplied to the load unit without increasing the capacitance of the capacitor. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a block diagram showing an example of a battery charging device according to an embodiment of the present invention; [Figure 2A] FIG. 3 is a first diagram illustrating the battery abnormality determination process of the battery charging device according to the present embodiment. [Figure 2B] FIG. 2 is a second diagram illustrating the battery abnormality determination process of the battery charging device according to the present embodiment. [Figure 3] 4 is a flowchart showing an example of the operation of the battery charging device according to the present embodiment. [Figure 4] 4 is a timing chart showing an example of the operation of the battery charging device according to the present embodiment. [Figure 5] FIG. 4 is a diagram showing an example of a ripple current in a capacitor of the battery charging device according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A battery charging device according to an embodiment of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing an example of a battery charging device 1 according to this embodiment.

[0015] 1, the battery charging device 1 is connected to a battery 3 and an FI load unit 4, and includes a generator 2 and a regulator 10. The battery charging device 1 is mounted on a vehicle such as a motorcycle, and half-wave rectifies AC power generated by the generator 2 to charge the battery 3. The FI load unit 4 is also connected to the battery charging device 1 via a diode 12, and supplies the power generated by the generator 2 or the output power of the battery 3 to the FI load unit 4.

[0016] The generator 2 is, for example, a single-phase magneto AC generator that generates electricity in response to the rotation of a rotor (not shown) and outputs an AC signal corresponding to the generated power. Here, the rotor is, for example, a crankshaft connected to the rotating shaft of an internal combustion engine (engine) of a motorcycle. The generator 2 transmits the AC signal corresponding to the generated power to a thyristor 11 via a power supply line.

[0017] The battery 3 is, for example, a lead storage battery, and its + (plus) electrode (positive electrode) is connected to the cathode terminal (output line L1) of the thyristor 11, and its - (minus) electrode (negative electrode) is connected to the ground terminal (ground line L2). The battery 3 is charged with the power generated by the generator 2 supplied via the thyristor 11, and supplies the charged power to the FI load unit 4 via the diode 12.

[0018] The FI load unit 4 is, for example, an electrical component of the motorcycle, such as an ECU (Engine Control Unit), a fuel pump, an injector, various sensors, etc. The FI load unit 4 operates by receiving power generated by the generator 2 or output power from the battery 3 via a diode 12, and consumes power. In this embodiment, the FI load unit 4 is an example of a load unit.

[0019] The regulator 10 rectifies the AC power generated by the generator 2 to generate DC power for charging the battery 3 and DC power to be supplied to a load (e.g., the FI load 4). The regulator 10 includes a thyristor 11, diodes (12, 15, 16), a capacitor 13, a switching control unit 14, and a voltage control unit 17.

[0020] The thyristor 11 (an example of a switching element) is a silicon-controlled rectifier that rectifies the AC signal output by the generator 2 and supplies it as charging power to the battery 3. The thyristor 11 has an anode terminal connected to the output line of the generator 2, a cathode terminal connected to the positive electrode of the battery 3 via a node N1 (output line L1), and a gate terminal (control terminal) connected to a signal line for a control signal S2 output by the voltage control unit 17.

[0021] When the thyristor 11 is turned on by a control signal S2 from the voltage control unit 17, it supplies the positive voltage of the AC signal output by the generator 2 to the positive electrode of the battery 3, charging the battery 3 and supplying operating power to the FI load unit 4. In other words, the thyristor 11 rectifies the AC signal output by the generator 2 and supplies it as charging power to the battery 3. The thyristor 11 is controlled to be on during the period when the AC signal is positive voltage, and supplies DC power (DC voltage) to the battery 3 and the FI load unit 4 by half-wave rectification.

[0022] The diode 12 is connected between the output line L1 of the thyristor 11 and the FI load unit 4, and supplies operating power to the FI load unit 4. The anode terminal of the diode 12 is connected to the output line L1, and the cathode terminal is connected to the FI load unit 4 via a node N2 (output line L3), thereby preventing a reverse flow of current from the FI load unit 4. The output line L3 (node ​​N2) of the diode 12 is connected to a capacitor 13, a switching control unit 14, and a diode 15.

[0023] The capacitor 13 is, for example, an electrolytic capacitor, and is connected to the output line L3 of the diode 12, and is connected in parallel with the FI load unit 4. The capacitor 13 is connected between the output line L3 and the ground line L2, and smoothes the voltage half-wave rectified by the thyristor 11 via the diode 12.

[0024] When the battery 3 falls into an abnormal state that makes it unusable, the switching control unit 14 reduces the set voltage of the voltage control unit 17, which will be described later. An abnormal state in which the battery 3 is unusable here means, for example, when the battery 3 is disconnected, when a fuse (not shown) is blown, when the performance of the battery 3 has deteriorated and it is no longer possible to output a usable voltage, etc. Note that an abnormal state in which the battery 3 is unusable may also include, for example, when the output voltage of the battery 3 fluctuates greatly up and down in response to a change in the load.

[0025] For example, when the voltage VC of the output line L3 of the diode 12 is greater than the voltage VB of the output line L1 of the thyristor 11 while the thyristor 11 is in the off state (non-conducting state), the switching control unit 14 determines that an abnormal state exists. Furthermore, the switching control unit 14 determines whether or not an abnormal state exists while the AC signal is at a negative voltage. If the switching control unit 14 determines that an abnormal state exists, it outputs a signal to the signal line of the switching signal S1 to lower the set voltage of the voltage control unit 17.

[0026] Specifically, in a normal state where the battery 3 is usable, the switching control unit 14 sets the set voltage of the voltage control unit 17 to a set voltage V1 (first set voltage) for charging the battery 3. In addition, in an abnormal state, the switching control unit 14 switches the set voltage of the voltage control unit 17 to a set voltage V2 (second set voltage). The set voltage V2 is a voltage that can operate the FI load unit 4 and is lower than the set voltage V1.

[0027] The diode 15 has an anode terminal connected to the output line L3 (node ​​N2) and a cathode terminal connected to a node N3. The node N3 is connected to the voltage control unit 17. The diode 15 prevents a reverse current from flowing from the output line L1 (node ​​N1).

[0028] The anode terminal of the diode 16 is connected to the output line L1 (node ​​N1), and the cathode terminal is connected to a node N3. The diode 16 prevents a reverse current from flowing from the output line L3 (node ​​N2). The node N3 is supplied with the larger of the voltage VB and the voltage VC.

[0029] The voltage control unit 17 controls the conduction of the thyristor 11 so that the voltage VC supplied to the FI load unit 4 becomes the set voltage of the output target. The voltage control unit 17 controls the conduction of the thyristor 11 using the above-mentioned diodes 15 and 16 so that, for example, the larger of the voltage VB and the voltage VC (the voltage at node N3) becomes the set voltage of the output target. The voltage control unit 17 outputs a control signal S2 to the gate terminal of the thyristor 11 so that the voltage at node N3 becomes the set voltage. The voltage control unit 17 controls the conduction timing (ON timing) of the thyristor 11 using the control signal S2 so that the voltage VC supplied to the FI load unit 4 becomes the set voltage.

[0030] Furthermore, the voltage control unit 17 switches the set voltage in response to the switching signal S1 from the switching control unit 14. For example, when the switching signal S1 is a signal for switching to a set voltage V1 that is a high voltage when the battery 3 is in a normal state, the voltage control unit 17 switches the set voltage setting to the set voltage V1. Also, for example, when the switching signal S1 is a signal for switching to a set voltage V1 that is a low voltage when the battery 3 is in an abnormal state, the voltage control unit 17 switches the set voltage setting to the set voltage V2.

[0031] Next, the operation of the battery charger 1 according to this embodiment will be described with reference to the drawings. 2A and 2B are diagrams illustrating the battery abnormality determination process of the battery charging device 1 according to this embodiment.

[0032] 2A shows an example in which the thyristor 11 is in an off state and the battery 3 is normal. In this case, the capacitor 13 is charged with a voltage VC, which is expressed by the following equation (1).

[0033] VC=VB-VF <VB ··· (1)

[0034] As shown in equation (1), when the thyristor 11 is in the off state and the battery 3 is in a normal state, the voltage VC of the capacitor 13 (the voltage at node N2) is the voltage VB (the voltage at node N1) minus the forward voltage VF, and the voltage VC is a voltage smaller than the voltage VB. Note that the voltage VB is the output voltage of the battery 3. In addition, in FIGS. 2A and 2B, the load section 5 represents a load connected to the output line L1.

[0035] 2B shows an example of an abnormal state in which the thyristor 11 is in the OFF state and the battery 3 is disconnected. In this case, the voltage at the node N2 becomes the voltage VC charged in the capacitor 13 when the thyristor 11 is turned ON. Furthermore, since the battery 3 is not connected, the voltage VB at the node N1 is discharged via the load unit 5 and becomes 0 V. Therefore, the relationship between the voltage VC and the voltage VB is expressed by the following equation (2).

[0036] VC>VB=0V (2)

[0037] As shown in equation (2), when the thyristor 11 is in the OFF state and the battery 3 is in an abnormal state where it is disconnected, the voltage VC of the capacitor 13 (the voltage at the node N2) becomes higher than the voltage VB.

[0038] The switching control unit 14 utilizes the characteristics shown in Figures 2A and 2B described above to determine whether the battery 3 is in an abnormal state in which it cannot be used, and if it determines that the battery 3 is in an abnormal state, it outputs a switching signal S1 to the voltage control unit 17 to reduce the set voltage from set voltage V1 to set voltage V2.

[0039] Next, the switching process of the switching control unit 14 in this embodiment will be described in detail with reference to FIG. FIG. 3 is a flowchart showing an example of the operation of the battery charger 1 according to this embodiment.

[0040] 3, the switching control unit 14 of the battery charger 1 first determines whether the thyristor 11 is in an off period (step S101). The switching control unit 14 determines whether the thyristor 11 is in an off period, for example, based on the control signal S2 of the thyristor 11. If the thyristor 11 is in an off period (step S101: YES), the switching control unit 14 proceeds to step S102. If the thyristor 11 is not in an off period (step S101: NO), the switching control unit 14 returns the process to step S101.

[0041] In step S102, the switching control unit 14 determines whether the voltage VC (the voltage at node N2) is greater than the voltage VB (the voltage at node N1). If the voltage VC is greater than the voltage VB (VC>VB) (step S102: YES), the switching control unit 14 proceeds to step S103. If the voltage VC is equal to or less than the voltage VB (VC≦VB) (step S102: NO), the switching control unit 14 proceeds to step S104.

[0042] In step S103, the switching control unit 14 switches the set voltage of the voltage control unit 17 to the lower set voltage V2. That is, the switching control unit 14 outputs a switching signal S1 for switching the set voltage to the set voltage V2 to the voltage control unit 17, causing the set voltage to be switched to the set voltage V2. After the process of step S103, the switching control unit 14 returns the process to step S101.

[0043] In step S104, the switching control unit 14 switches the set voltage of the voltage control unit 17 to the higher set voltage V1. That is, the switching control unit 14 outputs a switching signal S1 for switching the set voltage to the set voltage V1 to the voltage control unit 17, causing the set voltage to be switched to the set voltage V1. After the process of step S104, the switching control unit 14 returns the process to step S101.

[0044] Next, an example of the operation of the battery charger 1 will be described with reference to FIG. FIG. 4 is a timing chart showing an example of the operation of the battery charger 1 according to this embodiment.

[0045] 4, waveform W1 represents the waveform of the output voltage of generator 2, waveform W2 represents the waveform of voltage VB (voltage at node N1), waveform W3 represents the waveform of switching signal S1, and waveform W4 represents the waveform of voltage VC (voltage at node N2). The horizontal axis of each waveform represents time.

[0046] 4, period TR1 indicates a period in a normal state in which the battery 3 is normally connected to the battery charger 1. In this case, voltage VB has a substantially constant voltage waveform as shown by waveform W2a. In this case, as shown in FIG. 2A, voltage VC is smaller than voltage VB, so switching control unit 14 outputs switching signal S1 (for example, a low state) that switches the set voltage to set voltage V1. In this case, voltage VC becomes a voltage as shown by waveform W4a.

[0047] Furthermore, period TR2 indicates a period of an abnormal state in which the battery 3 is disconnected. In this case, voltage VB takes on a waveform like waveform W2b and becomes 0 V during off-period TR3 of thyristor 11. In this case, during off-period TR3 of thyristor 11, voltage VC is higher than voltage VB, as shown in FIG. 2B, so switching control unit 14 outputs switching signal S1 (for example, High state) to switch the set voltage to set voltage V2. In this case, voltage VC becomes a voltage lower than the voltage of waveform W4b in period TR1, as shown in waveform W4b. Note that off-period TR3 of thyristor 11 corresponds to a period in which the AC signal output by generator 2 is a negative voltage.

[0048] In this way, in period TR2, the voltage control unit 17 switches the set voltage to set voltage V2, and controls so as to output voltage VC that is lower than that in period TR1 (see waveform W4b).

[0049] Next, the effects of the battery charger 1 according to this embodiment will be described with reference to FIG. FIG. 5 is a diagram showing an example of a ripple current in the capacitor 13 of the battery charger 1 according to this embodiment.

[0050] In the graph of FIG. 5, the horizontal axis indicates the rotation speed (r / min) of the generator 2, and the vertical axis indicates the effective value (Arms) of the ripple current Irp of the capacitor 13. Furthermore, waveform W5 shows the ripple current of capacitor 13 in battery charging device 1 of this embodiment when battery 3 is not connected. For comparison, waveform W6 shows the ripple current of capacitor 13 when battery 3 is not connected and the set voltage is left at set voltage V1. Waveform W6 corresponds to the ripple current of capacitor 13 in battery charging device 1 of the prior art.

[0051] As shown by waveform W5 in FIG. 5, in the battery charger 1 according to this embodiment, the set voltage is lowered to set voltage V2, thereby making it possible to reduce the ripple current in capacitor 13 compared to the prior art (waveform W6).

[0052] As described above, the battery charging device 1 according to this embodiment includes the generator 2, the thyristor 11 (switching element), the diode 12, the capacitor 13, the voltage control unit 17, and the switching control unit 14. The generator 2 generates electricity in response to the rotation of its rotor and outputs an AC signal corresponding to the generated power. The thyristor 11 rectifies the AC signal output by the generator 2 and supplies it to the battery 3 as charging power. The diode 12 is connected between the output line L1 of the thyristor 11 and the FI load unit 4 (load unit) and supplies operating power to the FI load unit 4. The capacitor 13 is connected to the output line L3 of the diode 12 and is connected in parallel with the FI load unit 4. The voltage control unit 17 controls the conduction of the thyristor 11 so that the voltage supplied to the FI load unit 4 becomes the set voltage, which is the output target. The switching control unit 14 lowers the set voltage (for example, switches it to set voltage V2) when the battery 3 falls into an abnormal state that makes it unusable.

[0053] As a result, when the battery 3 falls into an abnormal state that makes it unusable, the battery charging device 1 according to this embodiment can reduce the ripple current Irp of the current supplied to the FI load unit 4, as shown in, for example, the waveform W5 illustrated in Fig. 5 described above. Therefore, the battery charging device 1 according to this embodiment does not need to increase the capacity of the capacitor 13. In other words, the battery charging device 1 according to this embodiment can reduce the ripple current Irp of the current supplied to the load unit (FI load unit 4) without increasing the capacity of the capacitor 13.

[0054] In addition, in this embodiment, when the voltage VC of the output line L3 of the diode 12 is higher than the voltage VB of the output line L1 of the thyristor 11 during the period when the thyristor 11 is in the off state (non-conducting state), the switching control unit 14 determines that an abnormal state has occurred.

[0055] As a result, the battery charging device 1 of this embodiment can easily determine that the battery 3 is in an abnormal state in which it cannot be used by using a simple method of comparing the voltage VC of the output line L3 with the voltage VB of the output line L1 while the thyristor 11 is in the off state (non-conducting state).

[0056] In this embodiment, the switching control unit 14 determines whether or not an abnormal state exists during the period when the AC signal output by the generator 2 is at a negative voltage. As a result, the battery charging device 1 according to this embodiment can easily determine that the battery 3 is in an abnormal state that makes it unusable, for example, by comparing the voltage VC of the output line L3 with the voltage VB of the output line L1 during the period when the AC signal output by the generator 2 is a negative voltage.

[0057] In this embodiment, in a normal state where the battery 3 is usable, the switching control unit 14 sets the set voltage to a set voltage V1 (first set voltage) for charging the battery 3. When the battery 3 is in an abnormal state, the switching control unit 14 switches the set voltage to a set voltage V2 (second set voltage) that is lower than the set voltage V1 and that allows the FI load unit 4 to operate.

[0058] As a result, the battery charging device 1 according to this embodiment can reduce the ripple current Irp of the capacitor 13 by switching the set voltage of the voltage control unit 17 to a set voltage V2 that is lower than the set voltage V1 and that allows the FI load unit 4 to operate. Therefore, the battery charging device 1 according to this embodiment can properly operate the FI load unit 4 even in an abnormal state such as when the battery 3 is disconnected. In other words, the battery charging device 1 according to this embodiment can properly operate a vehicle (e.g., a motorcycle) equipped with the battery charging device 1 even in an abnormal state in which the battery 3 is disconnected.

[0059] In this embodiment, the switching element is a thyristor (silicon controlled rectifier) ​​11. The voltage control unit 17 controls the conduction timing of the thyristor 11 so that the voltage VC supplied to the FI load unit 4 becomes a set voltage.

[0060] As a result, the battery charger 1 according to this embodiment can appropriately rectify the AC signal output by the generator 2 with a simple configuration by using the thyristor 11 (silicon controlled rectifier) ​​as the switching element.

[0061] In this embodiment, the abnormal state also includes a state in which the battery 3 is disconnected from its own device (battery charging device 1). As a result, the battery charging device 1 of this embodiment can properly operate load sections such as the FI load section 4 without increasing the capacity of the capacitor 13, even if the battery 3 enters an abnormal state in which it is disconnected from its own device (battery charging device 1).

[0062] The present invention is not limited to the above-described embodiment, and can be modified within the scope of the present invention. For example, in the above embodiment, the switching element is described as a thyristor 11, but this is not limited to this, and other switching elements may be used, such as a MOS (Metal-Oxide-Semiconductor) transistor, an IGBT (Insulated Gate Bipolar Transistor), or other silicon-controlled rectifiers.

[0063] In addition, in the above embodiment, the generator 2 is described as a single-phase magneto AC generator, but is not limited to this and may be a generator that outputs AC signals of multiple phases (e.g., three phases), or may be another generator.

[0064] In the above embodiment, the processing of the switching control unit 14 and the voltage control unit 17 may be realized by software processing or by hardware processing such as an electronic circuit. That is, the switching control unit 14 and the voltage control unit 17 may be realized by circuit means or by software processing that causes a CPU (Central Processing Unit) to execute a program.

[0065] In the battery charging device 1, if the processing of the switching control unit 14 and the voltage control unit 17 is realized by hardware processing such as an electronic circuit, the set voltage of the voltage control unit 17 can be quickly switched in response to the occurrence of an abnormal state in which the battery 3 cannot operate normally. In other words, the battery charging device 1 can quickly respond to the occurrence of an abnormal state.

[0066] Furthermore, in the above embodiment, an example has been described in which the switching control unit 14 and the voltage control unit 17 are realized with different configurations, but this is not limiting, and for example, part or all of the switching control unit 14 may be provided in the voltage control unit 17. For example, the switching control unit 14 may determine whether or not the voltage VC of the output line L3 is higher than the voltage VB of the output line L1, and the voltage control unit 17 may determine an abnormal state, such as connection of the battery 3, based on the determination result of whether or not the voltage VC of the output line L1 is higher than the voltage VB while the thyristor 11 is in the off state.

[0067] In the above embodiment, some or all of the functions of the switching control unit 14 and the voltage control unit 17 may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each of the above functions may be implemented individually as a processor, or some or all of the functions may be integrated into a processor.

[0068] Furthermore, the integrated circuit method is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology, an integrated circuit based on that technology may also be used. [Explanation of symbols]

[0069] 1 Battery charging device 2. Generator 3 Battery 4 FI load section 5 Load section 10 Regulator 11 Thyristor 12, 15, 16 Diodes 13 Capacitor 14 Switching control section 17 Voltage control section

Claims

1. a generator that generates electricity in response to rotation of the rotor and outputs an AC signal in response to the generated electricity; a switching element that rectifies the AC signal output by the generator and supplies the rectified AC signal to a battery as charging power; a diode connected between an output line of the switching element and a load section, the diode supplying operating power to the load section; a capacitor connected to an output line of the diode and connected in parallel with the load section; a voltage control unit that controls conduction of the switching element so that the voltage supplied to the load unit becomes a set voltage of an output target; a switching control unit that reduces the set voltage when the battery is in an abnormal state that makes it unusable; A battery charging device comprising:

2. The switching control unit determines that the abnormal state exists when the voltage of the output line of the diode is higher than the voltage of the output line of the switching element during a period when the switching element is in a non-conductive state.

2. The battery charging device according to claim 1.

3. The switching control unit determines whether the abnormal state occurs during a period in which the AC signal is at a negative voltage.

2. The battery charging device according to claim 1.

4. The switching control unit In a normal state where the battery is usable, the set voltage is set to a first set voltage for charging the battery; When the abnormal state occurs, the set voltage is switched to a second set voltage that is lower than the first set voltage and that allows the load unit to operate. The battery charging device according to any one of claims 1 to 3.

5. the switching element is a thyristor, The voltage control unit The conduction timing of the switching element is controlled so that the voltage supplied to the load unit becomes the set voltage. The battery charging device according to any one of claims 1 to 3.

6. The abnormal state includes a state in which the battery is disconnected from the device. The battery charging device according to any one of claims 1 to 3.

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