JP7734855B2 - Battery charging device - Google Patents

Description

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.

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

WO 2016/132440

In recent years, for example, in motorcycles, the load connected to the generator and battery has increased due to electronic control using FI (Fuel Injection: Electronically Controlled Fuel Injection) and an increase in sensors. However, with the conventional battery charging device described above, for example, if the battery is disconnected, the ripple current supplied to the load section increases, posing a problem in that it becomes necessary to increase the capacity of the capacitor connected in parallel to the load section.

The present invention has been made to solve the above problem, 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.

In order to solve the above problem, 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 the output target set voltage; and a switching control section that lowers the set voltage when the battery enters an abnormal state that makes it unusable.

In another aspect of the present invention, 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.

In another aspect of the present invention, in the above-mentioned battery charging device, the switching control unit may determine whether or not the abnormal state exists during a period in which the AC signal is a negative voltage.

In another aspect of the present invention, in the above-mentioned battery charging device, the switching control unit may set 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, switch the set voltage to a second set voltage that is lower than the first set voltage and that allows the load unit to operate.

Furthermore, 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.

Furthermore, in one aspect of the present invention, in the above-mentioned battery charging device, the abnormal state may include a state in which the battery is disconnected from the device itself.

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 that makes it unusable. This allows the battery charging device to reduce the ripple current in the current supplied to the load unit when the battery enters an abnormal state that makes it unusable, eliminating the need to increase the capacitance of the capacitor. In other words, the battery charging device can reduce the ripple current in the current supplied to the load unit without increasing the capacitance of the capacitor.

1 is a block diagram showing an example of a battery charging device according to an embodiment of the present invention; 1 is a first diagram illustrating a battery abnormality determination process of the battery charging device according to the present embodiment. FIG. FIG. 10 is a second diagram illustrating the battery abnormality determination process of the battery charging device according to the present embodiment. 4 is a flowchart showing an example of the operation of the battery charging device according to the present embodiment. 4 is a timing chart showing an example of the operation of the battery charging device according to the present embodiment. 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 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.

As shown in FIG. 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.

The generator 2 is, for example, a single-phase magneto-type 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 outputs an AC signal corresponding to the generated power to the thyristor 11 via a power supply line.

The battery 3 is, for example, a lead-acid battery, with its + (plus) electrode (positive electrode) connected to the cathode terminal (output line L1) of the thyristor 11 and its - (minus) electrode (negative electrode) 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 section 4 via the diode 12.

The FI load section 4 is, for example, an electrical component of a motorcycle, such as an ECU (Engine Control Unit), a fuel pump, an injector, and various sensors. The FI load section 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 section 4 is an example of a load section.

The regulator 10 rectifies the AC power generated by the generator 2 to generate DC power for charging the battery 3 and DC power for supplying 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.

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

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

Diode 12 is connected between output line L1 of thyristor 11 and FI load section 4, and supplies operating power to FI load section 4. Diode 12 has an anode terminal connected to output line L1 and a cathode terminal connected to FI load section 4 via node N2 (output line L3), preventing backflow of current from FI load section 4. In addition, output line L3 (node N2) of diode 12 is connected to capacitor 13, switching control section 14, and diode 15.

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

When the battery 3 falls into an abnormal state that makes it unusable, the switching control unit 14 lowers 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 refers to, for example, when the battery 3 is disconnected, when a fuse (not shown) is blown, or when the performance of the battery 3 has deteriorated and it is no longer able to output a usable voltage. 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 significantly up and down in response to fluctuations in the load.

The switching control unit 14 determines that an abnormal state exists when, for example, 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 also determines whether 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.

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 set voltage V1 (first set voltage) for charging the battery 3. Furthermore, in an abnormal state, the switching control unit 14 switches the set voltage of the voltage control unit 17 to set voltage V2 (second set voltage). Set voltage V2 is a voltage that can operate the FI load unit 4 and is lower than set voltage V1.

Diode 15 has its anode terminal connected to output line L3 (node N2) and its cathode terminal connected to node N3. Node N3 is connected to voltage control unit 17. Diode 15 prevents backflow of current from output line L1 (node N1).

Diode 16 has an anode terminal connected to output line L1 (node N1) and a cathode terminal connected to node N3. Diode 16 prevents backflow of current from output line L3 (node N2). Node N3 is supplied with the larger of voltages VB and VC.

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 voltages VB and 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 also 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.

The voltage control unit 17 also switches the set voltage in response to the switching signal S1 from the switching control unit 14. For example, if the switching signal S1 is a signal to switch to the set voltage V1, which 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, if the switching signal S1 is a signal to switch to the set voltage V1, which 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.

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.

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

VC=VB-VF<VB... (1)

As shown in equation (1), when thyristor 11 is off and battery 3 is normal, voltage VC of capacitor 13 (voltage at node N2) is voltage VB (voltage at node N1) minus forward voltage VF, and voltage VC is smaller than voltage VB. Voltage VB is the output voltage of battery 3. Also, in Figures 2A and 2B, load section 5 represents the load connected to output line L1.

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

VC>VB=0V... (2)

As shown in equation (2), when thyristor 11 is in the off state and an abnormal state occurs in which battery 3 is disconnected, the voltage VC of capacitor 13 (the voltage at node N2) becomes higher than voltage VB.

The switching control unit 14 uses 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 it 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.

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 charging device 1 according to this embodiment.

As shown in FIG. 3, the switching control unit 14 of the battery charging device 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.

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

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 to the voltage control unit 17 to switch the set voltage to the set voltage V2, causing the set voltage to be switched to the set voltage V2. After processing step S103, the switching control unit 14 returns the processing to step S101.

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 to the voltage control unit 17 to switch the set voltage to the set voltage V1, causing the set voltage to be switched to the set voltage V1. After processing step S104, the switching control unit 14 returns the processing to step S101.

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.

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

In addition, in Figure 4, period TR1 indicates a period in a normal state in which battery 3 is normally connected to battery charging device 1. In this case, voltage VB has an approximately constant voltage waveform, as shown in waveform W2a. In this case, as shown in Figure 2A, voltage VC is smaller than voltage VB, so the switching control unit 14 outputs switching signal S1 (e.g., a low state) to switch the set voltage to set voltage V1. In this case, voltage VC becomes the voltage shown in waveform W4a.

Furthermore, period TR2 indicates the 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 the off period TR3 of thyristor 11. In this case, during the off period TR3 of thyristor 11, voltage VC is greater than voltage VB, as shown in FIG. 2B, so the switching control unit 14 outputs a switching signal S1 (e.g., a high state) that switches 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. The off period TR3 of thyristor 11 corresponds to the period in which the AC signal output by the generator 2 is a negative voltage.

In this way, during period TR2, the voltage control unit 17 switches the set voltage to set voltage V2 and controls the output voltage VC to be lower than during period TR1 (see waveform W4b).

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.

In FIG. 5, the horizontal axis of the graph 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.
Waveform W5 shows the ripple current of capacitor 13 in the battery charging device 1 of this embodiment when the battery 3 is not connected. Waveform W6, for comparison, shows the ripple current of capacitor 13 when the 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 the battery charging device 1 of the prior art.

As shown in waveform W5 in Figure 5, in the battery charging device 1 of this embodiment, the set voltage is lowered to set voltage V2, thereby reducing the ripple current of capacitor 13 compared to the conventional technology (waveform W6).

As described above, the battery charging device 1 according to this embodiment includes a generator 2, a thyristor 11 (switching element), a diode 12, a capacitor 13, a voltage control unit 17, and a switching control unit 14. The generator 2 generates electricity in response to the rotation of the 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 output target set voltage. The switching control unit 14 lowers the set voltage (for example, switches it to set voltage V2) when the battery 3 enters an abnormal state that makes it unusable.

As a result, when the battery 3 enters 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 section 4, as shown in waveform W5 in Figure 5 above. Therefore, the battery charging device 1 according to this embodiment does not need to increase the capacity of 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 section (FI load section 4) without increasing the capacity of capacitor 13.

In addition, in this embodiment, the switching control unit 14 determines that an abnormal state exists 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 during the period when the thyristor 11 is in the off state (non-conducting state).

As a result, the battery charging device 1 of this embodiment can easily determine that the battery 3 is in an abnormal state that makes it unusable by using the simple method of comparing the voltage VC of the output line L3 with the voltage VB of the output line L1 during the period when the thyristor 11 is in the off state (non-conducting state).

In this embodiment, the switching control unit 14 determines whether or not an abnormal state exists during a period in which 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.

In addition, in this embodiment, when the battery 3 is in a normal state where it can be used, the switching control unit 14 sets the set voltage to a set voltage V1 (first set voltage) that charges 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 can operate the FI load unit 4 and is lower than the set voltage V1.

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 set voltage V2, which is lower than set voltage V1 and allows operation of the FI load unit 4. 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.

In this embodiment, the switching element is a thyristor 11 (silicon-controlled rectifier). 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 the set voltage.

As a result, the battery charging device 1 of this embodiment can appropriately rectify the AC signal output by the generator 2 with a simple configuration by using a thyristor 11 (silicon controlled rectifier) as a switching element.

In this embodiment, the abnormal state also includes a state in which the battery 3 is disconnected from the device itself (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).

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, an example has been described in which the switching element is a thyristor 11, but this is not limited to this, and other switching elements may be used, such as MOS (Metal-Oxide-Semiconductor) transistors, IGBTs (Insulated Gate Bipolar Transistors), other silicon-controlled rectifiers, etc.

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

Furthermore, 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 electronic circuits. In other words, 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.

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

In addition, in the above embodiment, an example has been described in which the switching control unit 14 and the voltage control unit 17 are configured differently, but this is not limited to this. For example, part or all of the switching control unit 14 may be provided by the voltage control unit 17. For example, the switching control unit 14 may determine whether the voltage VC of the output line L3 is greater than the voltage VB of the output line L1, and the voltage control unit 17 may determine an abnormal state, such as the connection of the battery 3, based on the result of the determination of whether the voltage VC of the output line L1 is greater than the voltage VB while the thyristor 11 is in the off state.

In addition, 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 them may be integrated into a processor.

In addition, the integrated circuit method is not limited to LSI, and may be realized using dedicated circuits or general-purpose processors. Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology, integrated circuits using that technology may also be used.

REFERENCE SIGNS LIST 1 Battery charging device 2 Generator 3 Battery 4 FI load section 5 Load section 10 Regulator 11 Thyristor 12, 15, 16 Diode 13 Capacitor 14 Switching control section 17 Voltage control section

Claims (6)

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 falls into an abnormal state that makes it unusable. 2. The battery charging device according to claim 1, wherein the switching control unit determines that the abnormal state occurs when a voltage on an output line of the diode is higher than a voltage on an output line of the switching element during a period when the switching element is in a non-conductive state. The battery charging device according to claim 1 , wherein the switching control unit determines whether the abnormal state occurs while the AC signal is at a negative voltage. 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;
The battery charging device according to claim 1 , wherein, 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 switching element is a thyristor,
The voltage control unit
The battery charging device according to claim 1 , wherein the timing of conduction of the switching element is controlled so that the voltage supplied to the load section becomes the set voltage. The battery charging device according to claim 1 , wherein the abnormal state includes a state in which the battery is disconnected from the device itself.