Battery charging device, control device and protection method

Abstract

A battery charging device according to the present invention comprises: a switching element that rectifies an AC voltage generated by a generator by controlling an ON state and supplies a charging voltage to a battery; a control signal generation unit that outputs a control signal for the switching element on the basis of a control voltage obtained by boosting a power supply voltage output from the battery; and a control unit that controls the control signal so that the switching element is in a non-conductive state when a differential voltage of the control voltage, which is based on a voltage of a power supply line connected to the battery and connected to the battery-side terminal of the switching element, is equal to or less than a predetermined threshold voltage.

Description

Technical Field

[0001] The present invention relates to a battery charging device, a control device, and a protection method.

[0002] This application claims priority based on Japanese Patent Application No. 2022-198502 filed in Japan on December 13, 2022, the content of which is incorporated herein by reference. Background Art

[0003] Conventionally, in the case of performing switching control on a voltage higher than the power supply voltage, the power supply voltage is boosted to obtain a control signal for switching a switching element such as a MOSFET (metal oxide semiconductor field effect transistor). For example, in a conventional battery charging device, a control power supply obtained by boosting the power supply voltage output from the battery is used to control a switching element for converting an AC voltage generated by a generator into a charging voltage of the battery.

[0004] [Prior Art Documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-246293

[0006] However, for example, in a battery charging device mounted on a motorcycle or the like, during the power generation of the generator, there may be a case where the main switch may be turned off and the power supply voltage of the battery is cut off. In this way, when the supply of the power supply voltage is stopped during power generation, in a conventional battery charging device, since the control voltage drops, a switching element such as a MOSFET switches in an unsaturated region which is a region out of the saturation region. In this case, due to the decrease in the control voltage, the resistance of the switching element increases, resulting in heat generation of the switching element, and there is a possibility of deterioration and failure of the switching element.

[0007] The present invention has been made in view of the above problems, and an object thereof is to provide a battery charging device, a control device, and a protection method that can protect a switching element when the supply of the power supply voltage is stopped during power generation. Summary of the Invention

[0008] To solve the above problems, a battery charging device according to an embodiment of the present invention includes: a switching element that rectifies an AC voltage generated by a generator by controlling its conduction state and supplies a charging voltage to a battery; a control signal generation unit that outputs a control signal for the switching element based on a control voltage obtained by boosting a power supply voltage output from the battery; and a control unit that controls the control signal to make the switching element non-conductive when a differential voltage of the control voltage with respect to a voltage of a power line connected to the battery and to a terminal on the battery side of the switching element is less than or equal to a specified threshold voltage.

[0009] In addition, a battery charging device according to an embodiment of the present invention includes: a memory for storing a program; and a CPU that executes the program stored in the memory, wherein the control unit is implemented by causing the CPU to execute the program stored in the memory.

[0010] In addition, a battery charging device according to an aspect of the present invention includes: an analog-to-digital converter that detects the voltage of the power line and the control voltage, wherein the control unit calculates the differential voltage based on the voltage of the power line and the control voltage detected by the analog-to-digital converter.

[0011] In addition, in the battery charging device according to an aspect of the present invention, the specified threshold voltage includes a first threshold voltage and a second threshold voltage higher than the first threshold voltage. The control unit controls the control signal to make the switching element non-conductive when the differential voltage is less than or equal to the first threshold voltage, and controls the conduction state of the switching element to rectify the AC voltage when the differential voltage is higher than the second threshold voltage.

[0012] In addition, a control device according to an aspect of the present invention includes: a switching element that rectifies an AC voltage generated by a generator by controlling its conduction state and supplies a charging voltage to a battery; and a control signal generation unit that outputs a control signal for the switching element based on a control voltage obtained by boosting a power supply voltage output from the battery. The control device is characterized by including: a control unit that controls the control signal to make the switching element non-conductive when a differential voltage of the control voltage with respect to a voltage of a power line connected to the battery and to a terminal on the battery side of the switching element is less than or equal to a specified threshold voltage.

[0013] In addition, a protection method according to one aspect of the present invention includes: a switching element that rectifies an AC voltage generated by a generator by controlling its conduction state and supplies a charging voltage to a battery; and a control signal generation unit that outputs a control signal for the switching element based on a control voltage obtained by boosting a power supply voltage output from the battery. The protection method is characterized by including: a control step in which a control unit controls the control signal to make the switching element non-conductive when a differential voltage of the control voltage with respect to a voltage of a power line connected to the battery side terminal of the switching element is less than or equal to a specified threshold voltage.

[0014] Advantages of the Invention

[0015] According to the present invention, when the differential voltage of the control voltage with respect to the voltage of the power line connected to the battery side terminal of the switching element is less than or equal to the specified threshold voltage, the control unit controls the control signal to make the switching element non-conductive. By doing so, the battery charging device can prevent the switching element from being conductive in a region deviating from the saturation region, i.e., an unsaturated region, thereby reducing heat generation of the switching element. Therefore, the battery charging device can protect the switching element when the power supply voltage is stopped during power generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a block diagram of a battery charging device according to a first embodiment.

[0017] Figure 2 is a configuration example diagram of a main part of a battery charging device according to a first embodiment.

[0018] Figure 3 is a flowchart of an operation example of a battery charging device according to a first embodiment.

[0019] Figure 4 is a flowchart of an operation example of a battery charging device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, a battery charging device, a control device, and a protection method according to an embodiment of the present invention will be described with reference to the drawings.

[0021] [First Embodiment]

[0022] Figure 1 is a block diagram of a battery charging device 1 according to a first embodiment.

[0023] As Figure 1As shown, the battery charging device 1 includes: a diode 11, capacitors (12, 19), a voltage conversion unit 13, a control signal generation unit 14, resistors (15, 16, 18), a control unit 17, and switching elements (21 to 23, 31 to 33).

[0024] The battery charging device 1 is connected to the generator 2 and is connected to the battery 3 via the main switch unit 6. The battery charging device 1 is, for example, a device mounted on a vehicle such as a motorcycle, which rectifies the AC power generated by the generator 2 and charges the battery 3. In addition, the main switch unit 6 includes a main switch 4 and a main relay 5 for controlling the supply of the voltage (power supply voltage) of the battery 3 to the battery charging device 1.

[0025] The generator 2 is, for example, an ACG starter in which a starting motor and an ACG (alternator) are integrated and directly connected to the crankshaft. Here, the crankshaft is, for example, a rotor connected to the rotating shaft of an internal combustion engine (engine) of a motorcycle.

[0026] The battery 3 is, for example, a lead-acid battery, and its - (negative) electrode (negative terminal) is connected to the ground terminal (ground wire L1), and its + (positive) electrode (positive terminal) is connected to the power supply line L2. The + electrode of the battery 3 is connected to the main switch 4 and the main relay 5 through the power supply line L2. In addition, in the present embodiment, the output voltage of the battery 3 is defined as the power supply voltage VBAT.

[0027] The main switch 4 is, for example, the main switch of a vehicle such as a motorcycle. Its first end is connected to the + electrode (power supply line L2) of the battery 3, and its second end is connected to the node N1 for supplying power to the internal power supply. The main switch 4 is manually switched by the user to the on state (connected state) and the off state (non-connected state).

[0028] The main relay 5 (an example of the main switch) is connected between the power supply line L2 and the power supply line L3. When the main switch 4 is on and the node N1 becomes the power supply voltage VBAT, the main relay 5 becomes on, and the power supply line L2 and the power supply line L3 are connected. And when the main switch 4 is in the off state, the main relay 5 becomes in the off state, cutting off the power supply line L2 and the power supply line L3. In the present embodiment, the voltage of the power supply line L3 is defined as the voltage VP.

[0029] In this way, the main switch unit 6 controls the connection between the battery 3 and the power supply line L3 (the switching elements 21 to 23 described later), and the connection between the battery 3 and the node N1 (the voltage conversion unit 13 described later).

[0030] The anode terminal of the diode 11 is connected to the node N1, and the cathode terminal is connected to the node N2. The diode 11 supplies the output voltage (power supply voltage VBAT) of the battery 3 to the voltage conversion unit 13 and prevents current from flowing backward from the voltage conversion unit 13 to the battery 3.

[0031] The capacitor 12 is connected between the node N1 and the ground wire L1, and is a smoothing capacitor that smooths the output voltage (power supply voltage VBAT) of the battery 3 supplied to the voltage conversion unit 13.

[0032] The voltage conversion unit 13 is, for example, a power supply device that generates a high voltage and a low voltage from the output voltage (power supply voltage VBAT) of the battery 3. The voltage conversion unit 13 boosts the power supply voltage VBAT output from the battery 3, generates a voltage VH higher than the power supply voltage VBAT as a control voltage, and outputs it to the signal line L4. Also, the voltage conversion unit 13 generates the voltage of the control unit 17 from the power supply voltage VBAT output from the battery 3, and this voltage is lower than the voltage VH and is supplied to the control unit 17. In addition, the power supply voltage VBAT is supplied to the voltage conversion unit 13 via the main switch 4.

[0033] The control signal generation unit 14 is, for example, a gate driver that drives the gate electrodes of the switching elements 21 to 23 and the switching elements 31 to 33. The control signal generation unit 14 generates a control signal for the switching element 20 based on the control voltage (voltage VH) obtained by boosting the power supply voltage VBAT output from the battery 3. Also, for the sake of simplicity of explanation, although not shown in the figure, control signals are output to the gate terminals of the switching elements 22, 23, and 31 to 33 respectively. The control signal generation unit 14 generates a control signal for the switching element 20 according to the control of the control unit 17.

[0034] When the control signal generation unit 14 outputs a control signal for the switching element 21, the resistor 15 and the resistor 16 are connected to the control signal.

[0035] The first end of the resistor 15 is connected to the signal line of the control signal of the control signal generation unit 14, and the second end is connected to the node N3 (the gate terminal of the switching element 21). Also, the first end of the resistor 16 is connected to the node N3, and the second end is connected to the signal line of the drive signal U.

[0036] The resistor 15 and the resistor 16 are connected in series between the signal line of the control signal of the control signal generation unit 14 (the control signal line of the control voltage VH) and the signal line of the drive signal U.

[0037] Also, although not shown in the figure, resistors similar to the resistor 15 and the resistor 16 are also connected to the control signals of the switching elements 22, 23, and 31 to 33.

[0038] The switching elements 21 to 23 are, for example, N-type MOSFETs, and are high-side (high-side) switching elements that drive the starting motor when the generator 2 is used as a starting motor. In addition, in the present embodiment, when the switching elements 21 to 23 represent any high-side switching elements included in the battery charging device 1, or when there is no particular distinction, they are described as switching element 20.

[0039] The switching element 20 rectifies the AC voltage generated by the generator 2 by controlling the conduction state, and supplies the charging voltage to the battery 3.

[0040] In addition, since the switching element 20 is an N-type MOSFET, in order to reduce the on-resistance, a voltage higher than the source-drain voltage, which is the voltage between the source terminal and the drain terminal of the voltage supplied to the gate terminal control signal, needs to be provided. When the gate voltage drops compared to the source-drain voltage, the switching element 20 performs a conduction operation (non-saturation operation) in the saturation region, and the on-resistance of the switching element 20 increases, resulting in heat generation.

[0041] The drain terminal of the switching element 21 is connected to the power supply line L3 (the power supply line on the high potential side), the source terminal is connected to the node N4, and the control terminal (gate terminal) is connected to the node N3. In addition, the node N4 is the signal line of the drive signal U when the generator 2 is driven as a starting motor. In addition, each node N3 is a control signal output by the control signal generation unit 14, and is a signal line of the control signal driven by the control voltage VH.

[0042] The drain terminal of the switching element 22 is connected to the power supply line L3, the source terminal is connected to the node N5, and the control terminal (gate terminal) is connected to the output line of the control signal of the same control signal generation unit 14 as the node N3. In addition, the node N5 is the signal line of the drive signal V when the generator 2 is driven as a starting motor. The gate terminal of the switching element 22 is driven by the control voltage VH of the control signal output by the control signal generation unit 14.

[0043] The drain terminal of the switching element 23 is connected to the power supply line L3, the source terminal is connected to the node N6, and the control terminal (gate terminal) is connected to the output line of the control signal of the same control signal generation unit 14 as the node N3. In addition, the node N6 is the signal line of the drive signal W when the generator 2 is driven as a starting motor. The gate terminal of the switching element 23 is driven by the control voltage VH, and the control signal is output by the control signal generation unit 14.

[0044] The switching elements 31 to 33 are, for example, N-type MOSFETs, and are switching elements for driving the low side of the starting motor when the generator 2 is used as a starting motor. In addition, in the present embodiment, when the switching elements 31 to 33 represent any low-end switching elements included in the battery charging device 1, or when there is no particular distinction, they are described as the switching element 30.

[0045] The drain terminal of the switching element 31 is connected to the node N4, the source terminal is connected to the ground wire L1 (low-potential side power supply line) via the resistor 18, and the control terminal (gate terminal) is connected to the output line of the control signal of the control signal generation unit 14. In addition, the node N4 is the signal line of the drive signal U when driving the generator 2 as a starting motor.

[0046] The drain terminal of the switching element 32 is connected to the node N5, the source terminal is connected to the ground wire L1 via the resistor 18, and the control terminal (gate terminal) is connected to the output line of the control signal of the control signal generation unit 14. In addition, the node N5 is the signal line of the drive signal V when driving the generator 2 as a starting motor.

[0047] The drain terminal of the switching element 33 is connected to the node N6, the source terminal is connected to the ground wire L1 via the resistor 18, and the control terminal (gate terminal) is connected to the output line of the control signal of the control signal generation unit 14. In addition, the node N6 is the signal line of the drive signal W when driving the generator 2 as a starting motor.

[0048] The switching elements 20 (21 to 23) and the switching elements 30 (31 to 33) function as an inverter circuit when driving the generator 2 as a starting motor. In addition, the switching elements 20 (21 to 23) and the switching elements 30 (31 to 33) function as a rectifier circuit for rectifying the AC voltage generated by the generator 2 when charging the battery 3 from the generator 2.

[0049] The resistor 18 is connected between the switching element 30 (31 to 33) and the ground wire L1. The resistor 18 is, for example, a shunt resistor and is used for detecting the current flowing through the inverter circuit when driving the generator 2 as a starting motor.

[0050] The control unit 17 is, for example, a processor including a CPU (Central Processing Unit) and is used for comprehensively controlling the battery charging device 1. When driving the generator 2 as a starting motor, the control unit 17 controls the switching elements 20 (21 to 23) and the switching elements 30 (31 to 33) as an inverter circuit.

[0051] In the present embodiment, it is assumed that the control unit 17 is included in the control device 10.

[0052] In addition, when the control unit 17 charges the battery 3 from the generator 2, it controls the switching elements 20 (21 to 23) and the switching elements 30 (31 to 33) as a rectifier circuit.

[0053] When the differential voltage ΔV (= voltage VH - voltage VP) representing the control voltage VH with respect to the voltage VP of the power supply line L3 connected to the battery 3 is less than or equal to a specified threshold voltage (for example, less than or equal to the threshold voltage Vth), the control unit 17 controls the control signal to set the switching element 20 to the cut-off state (off state). Here, refer to Figure 2 for an explanation of the structure of the main part of the battery charging device 1 including the control unit 17.

[0054] Figure 2 is an example diagram of the structure of the main part of the battery charging device 1 of the present embodiment.

[0055] As Figure 2 shown, the main part of the battery charging device 1 includes a control device 10, a control signal generation unit 14, resistors (15, 16), and switching elements (21, 31).

[0056] The control device 10 includes: a resistor 101 and a resistor 102, a capacitor 103, a resistor 104 and a resistor 105, a capacitor 106, and a control unit 17.

[0057] The resistor 101 and the resistor 102 are connected in series between the power supply line L3 of the voltage VP and the ground line L1, and the voltage VP is converted into a voltage range that can be detected by the ADC171 described below through the resistance ratio between the resistor 101 and the resistor 102.

[0058] The resistor 101 has a first end connected to the power supply line L3 and a second end connected to the node N8. The resistor 102 has a first end connected to the node N8 and a second end connected to the ground line L1. The node N8 is connected to the first detection terminal of the ADC171 described later. The capacitor 103 is connected between the node N8 and the ground line L1 to perform resistive voltage division on the voltage VP and flatten the voltage at the node N8.

[0059] In addition, the resistor 104 and the resistor 105 are connected in series between the signal line L4 of the control voltage VH and the ground line, and the control voltage VH is converted into a voltage range that can be detected by the ADC171 (described later) through the resistance ratio of the resistor 104 to the resistor 105.

[0060] The resistor 104 has a first end connected to the node N9 and a second end connected to the signal line L4. The resistor 105 has a first end connected to the node N9 and a second end connected to the ground line L1. The node N9 is connected to the second detection terminal of the ADC171 described later. The capacitor 106 is connected between the node N9 and the ground line L1 to flatten the voltage of the node N9 after the voltage VH is resistively divided.

[0061] The control unit 17 includes an ADC171, a memory 172, and a CPU173.

[0062] The ADC171 (an example of an analog-to-digital converter) detects the voltage VP of the power supply line L3 and the control voltage VH. That is, the ADC171 detects the voltage value of the control voltage VH and the voltage value of the voltage VP. The control unit 17 calculates the differential voltage Δv based on the voltage VP of the power supply line L3 and the control voltage VH detected by the ADC171.

[0063] The memory 172 is, for example, a RAM or a flash memory, etc., and stores programs (such as a control program).

[0064] The CPU173 executes the programs stored in the memory 172.

[0065] The control unit 17 is implemented by causing the CPU173 to execute the programs stored in the memory 172. When the differential voltage ΔV becomes equal to or less than the threshold voltage Vth, the control unit 17 controls the signal generation unit 14 to output a signal SG to output the voltage of the ground line L1 as the control signal HSG to the switching element 21(20). In this case, the control signal generation unit 14 is in the state ST2 where the signal line of the control signal HSG is connected to the ground line L1.

[0066] In addition, when the differential voltage ΔV is greater than the threshold voltage Vth, the control unit 17 outputs a signal SG to cause the switching element 21(20) to function as a synchronous rectification element. Further, when the switching element 21(20) is controlled to be in the conducting state, the control signal generation unit 14 enters the state ST1 where the signal line of the control signal HSG is connected to the signal line L4 of the control voltage VH.

[0067] Next, with reference to the drawings, the operation of the battery charging device 1 of the present embodiment will be described.

[0068] Figure 3 It is a flowchart of an example of the operation of the battery charging device 1 of the present embodiment. Here, the protection process of the battery charging device 1 based on the control unit 17 (control device 10) will be described.

[0069] As Figure 3As shown, the control unit 17 of the battery charging device 1 first uses the ADC 171 to detect the voltage VP of the power supply line L3 and the control voltage VH (step S101). The control unit 17 detects the voltage VP by detecting the voltage of the node N8 that has been resistively divided by the resistors 101 and 102 through the ADC 171, and detects the control voltage VH by detecting the voltage of the node N9 that has been resistively divided by the resistors 104 and 105 through the ADC 171.

[0070] Then, the control unit 17 calculates the differential voltage ΔV (= control voltage VH - voltage VP) (step S102). The control unit 17 subtracts the voltage VP detected by the ADC 171 from the control voltage VH detected by the ADC 171 to calculate the differential voltage ΔV.

[0071] Then, the control unit 17 determines whether the differential voltage ΔV is below the threshold voltage Vth (differential voltage ΔV ≤ threshold voltage Vth) (step S103). When the difference voltage ΔV is equal to or less than the threshold voltage Vth (step S104: Yes), the control unit 17 advances the process to step S104. Additionally, when the difference voltage ΔV is greater than the threshold voltage Vth (step S105: No), the control unit 17 advances the process to step S105.

[0072] In step S104, the control unit 17 controls the switching element 20 to the off state. The control unit 17 connects the signal line of the control signal HSG and the ground line L1 to the control signal generation unit 14, and controls the gate terminal of the switching element 20 to the potential of the ground line L1 to turn off the switching element 20. After the processing in step S104, the control unit 17 returns the process to step S101.

[0073] In addition, in step S105, the control unit 17 controls the on state of the switching element 20 to rectify the AC voltage. The control unit 17 controls to rectify the AC voltage generated by the generator 2 through the switching element 20 to generate a charging voltage. After the processing in step S105, the control unit 17 returns the process to step S101.

[0074] As described above, the battery charging device 1 of the present embodiment includes: a switching element 20, a control signal generation unit 14, and a control unit 17. The switching element 20 rectifies the AC voltage generated by the generator 2 by being controlled to be in a conducting state (on state), and supplies a charging voltage to the battery 3. The control signal generation unit 14 outputs a control signal HSG for the switching element 20 based on a control voltage VH obtained by boosting the power supply voltage VBAT output from the battery 3. When the differential voltage ΔV representing the control voltage VH with respect to the voltage VP of the power supply line L3 connected to the battery side (battery 3 side) of the battery 3 and connected to the switching element 20 is less than or equal to a specified threshold voltage (less than or equal to the threshold voltage Vth), the control unit 17 controls the control signal HSG to set the switching element 20 to a cut-off state (non-conducting state).

[0075] Accordingly, the battery charging device 1 of the present embodiment can suppress the switching element 20 from being in a conducting state in a region deviating from the saturation region, i.e., an unsaturated region, and can reduce the heat generation of the switching element 20. Therefore, the battery charging device 1 of the present embodiment can protect the switching element 20, for example, when the power supply voltage VBAT is stopped from being supplied while the generator 2 is generating electricity. That is, for example, in the case where the battery charging device 1 is mounted on a two-wheeled vehicle or the like, in the battery charging device 1 of the present embodiment, when the generator is generating electricity (when the wheel is rotating) and the main switch 4 is turned off and the power supply voltage of the battery 3 is cut off, the switching element 20 can be protected.

[0076] In addition, in the switching element 20 in the unsaturated region, the on-resistance increases due to a low gate voltage, which causes abnormal heat generation of the switching element 20 and becomes a cause of failure. The battery charging device 1 of the present embodiment can prevent a failure caused by such abnormal heat generation of the switching element 20.

[0077] In addition, the battery charging device 1 according to the present embodiment includes a memory 172 for storing a program and a CPU 173 for executing the program stored in the memory 172. The control unit 17 can be implemented by causing the CPU 173 to execute the program stored in the memory 172.

[0078] Accordingly, the battery charging device 1 of the present embodiment can appropriately protect the switching element 20 by software processing, for example, when the power supply voltage VBAT is stopped from being supplied while the generator 2 is generating electricity, without adding special hardware.

[0079] In addition, the battery charging device 1 according to the present embodiment includes an ADC 171 (analog-to-digital converter) for detecting the voltage VP of the power supply line L3 and the control voltage VH. The control unit 17 calculates the differential voltage ΔV based on the voltage VP of the power supply line L3 and the control voltage VH detected by the ADC 171 (analog-digital converter).

[0080] Accordingly, the battery charging device 1 of the present embodiment can more accurately detect the voltage VP, the control voltage VH, and the differential voltage ΔV by using the ADC171, and thus can more appropriately protect the switching element 20.

[0081] In addition, the control device 10 of the battery charging device 1 of the present embodiment, the battery charging device 1 includes: a switching element 20 that rectifies the AC voltage generated by the generator 2 by controlling the conduction state and supplies a charging voltage to the battery 3; and a control signal generation unit 14 that outputs a control signal HSG of the switching element 20 according to the control voltage VH obtained by boosting the power supply voltage VBAT output from the battery 3. It is characterized in that: it includes a control unit 17. When the differential voltage ΔV of the control voltage VH with respect to the voltage VP of the power supply line L3 connected to the battery 3 and the terminal on the battery side (battery 3 side) connected to the switching element 20 is less than or equal to a specified threshold voltage (less than or equal to the threshold voltage Vth), the control unit 17 controls the control signal HSG to set the switching element 20 to the cut-off state (non-conduction state).

[0082] Accordingly, the battery charging device 1 of the present embodiment has the same effect as the above-mentioned battery charging device 1. For example, when the power supply voltage VBAT is stopped from being supplied while the generator 2 is generating power, the switching element 20 can be protected.

[0083] In addition, the protection method of the battery charging device 1 of the present embodiment, the battery charging device 1 includes: a switching element 20 that rectifies the AC voltage generated by the generator 2 by controlling the conduction state and supplies a charging voltage to the battery 3; and a control signal generation unit 14 that outputs a control signal HSG of the switching element 20 according to the control voltage VH obtained by boosting the power supply voltage VBAT output from the battery 3. It is characterized in that: it includes a control step. In the control step, when the differential voltage ΔV of the control voltage VH with respect to the voltage VP of the power supply line L3 connected to the battery 3 and the terminal on the battery side (battery 3 side) connected to the switching element 20 is less than or equal to a specified threshold voltage (less than or equal to the threshold voltage Vth), the control unit 17 controls the control signal HSG to set the switching element 20 to the cut-off state (non-conduction state).

[0084] Accordingly, the protection method of the present embodiment has the same effect as the above-mentioned battery charging device 1. For example, when the power supply voltage VBAT is stopped from being supplied while the generator 2 is generating power, the switching element 20 can be protected.

[0085] [Second Embodiment]

[0086] Next, the battery charging device 1 of the second embodiment will be described with reference to the accompanying drawings. In addition, in the second embodiment, the basic configuration of the battery charging device 1 is the same as that of the first embodiment shown in the above Figure 1 and Figure 2 , so the description thereof will be omitted here.

[0087] In this embodiment, the processing of the control unit 17 is different, and the points of change in the processing of the control unit 17 will be described here.

[0088] In this embodiment, the specified threshold voltage includes a threshold voltage Vth1 (first threshold voltage) and a threshold voltage Vth2 (second threshold voltage) higher than the threshold voltage Vth1. When the differential voltage ΔV is less than or equal to the threshold voltage Vth1 (less than or equal to the first threshold voltage), the control unit 17 of this embodiment controls the control signal HSG so that the switching element 20 is in an off state. In addition, when the differential voltage ΔV is higher than the threshold voltage Vth2 (second threshold voltage), the control unit 17 controls the on state of the switching element 20 to rectify the AC voltage.

[0089] Next, with reference to the accompanying drawings, the operation of the battery charging device 1 of the second embodiment will be described in detail.

[0090] Figure 4 is a flowchart of an example of the operation of the battery charging device 1 of the second embodiment.

[0091] Figure 4 In, the processing of step S201 and step S202 is the same as the processing of step S101 and step S102 shown in the above Figure 3 , so the description thereof will be omitted here.

[0092] In step S203, the control unit 17 determines whether the differential voltage ΔV is less than or equal to the threshold voltage Vth1 (differential voltage ΔV ≤ threshold voltage Vth1). When the differential voltage ΔV is less than or equal to the threshold voltage Vth1 (step S204: Yes), the control unit 17 advances the processing to step S204. In addition, when the differential voltage ΔV is greater than the threshold voltage Vth1 (step S205: No), the control unit 17 advances the processing to step S205.

[0093] In step S204, the control unit 17 controls the switching element 20 to be in an off state. The control unit 17 connects the signal line of the control signal HSG and the ground line L1 to the control signal generation unit 14, and controls the gate terminal of the switching element 20 to the potential of the ground line L1 to turn off the switching element 20. After the processing in step S204, the control unit 17 returns the processing to step S201.

[0094] In addition, in step S205, the control unit 17 determines whether the differential voltage ΔV is greater than the threshold voltage Vth2 (differential voltage ΔV > threshold voltage Vth2). When the differential voltage ΔV is greater than the threshold voltage Vth2 (step S206: Yes), the control unit 17 advances the process to step S206. In addition, when the differential voltage ΔV is less than or equal to the threshold voltage Vth2 (step S201: No), the control unit 17 returns the process to step S201.

[0095] In step S206, the control unit 17 changes to the process of controlling the conduction state of the switching element 20 to rectify the AC voltage. Thus, the control unit 17 controls so that the AC voltage generated by the generator 2 is rectified by the switching element 20 to generate a charging voltage. After the process of step S206, the control unit 17 returns the process to step S201.

[0096] As described above, in the present embodiment, the specified threshold voltage includes the threshold voltage Vth1 (first threshold voltage) and the threshold voltage Vth2 (second threshold voltage) higher than the threshold voltage Vth1. When the differential voltage ΔV is less than or equal to the threshold voltage Vth1 (less than or equal to the first threshold voltage), the control unit 17 controls the control signal HSG to turn the switching element 20 into the cut-off state. In addition, when the differential voltage ΔV is higher than the threshold voltage Vth2 (second threshold voltage), the control unit 17 controls the conduction state of the switching element 20 to rectify the AC voltage.

[0097] Thus, the battery charging device 1 of the present embodiment can make the control of the switching element 20 to the cut-off state and the control to the conduction state in a manner of rectifying the AC voltage have hysteresis. For example, it can reduce the failures caused by noise near the specified threshold voltage.

[0098] The present invention is not limited to the above-described embodiment and can be changed without departing from the gist of the present invention.

[0099] For example, in the above-described embodiments, an example in which the generator 2 is an ACG starter that integrates a starting motor and an ACG (alternator) and is directly connected to the crankshaft is described, but it is not limited thereto. The generator 2 can be, for example, a single-phase magnet type alternator or other types of generators.

[0100] In addition, in the above-described embodiments, an example in which the battery charging device 1 and the control device 10 are used for vehicle applications such as motorcycles is described, but it is not limited thereto, and it can also be applied to other applications.

[0101] In addition, in each of the above-described embodiments, an example has been described in which the control unit 17 uses the ADC 171 to detect the voltage VP and the control voltage VH, and calculates the differential voltage ΔV through the operation of the CPU 173. However, the present invention is not limited thereto. For example, the control unit 17 may use a comparator or the like instead of the ADC 171 to determine whether the voltage VP, the control voltage VH, and the differential voltage ΔV are less than or equal to a specified threshold voltage.

[0102] In addition, in each of the above-described embodiments, an example has been described in which the power supply line L3 connected to the high-potential side of the switching element 20 is connected to the battery 3 via the main relay 5 of the main switch unit 6. However, the present invention is not limited thereto, and a configuration may be adopted in which the power supply line L3 is directly connected to the battery 3 without including the main relay 5.

[0103] In addition, in each of the above-described embodiments, an example has been described in which the voltage conversion unit 13 and the control signal generation unit 14 have different structures. However, the present invention is not limited thereto. For example, the control signal generation unit 14 may have a structure that includes a part or all of the voltage conversion unit 13.

[0104] In addition, in the above-described embodiment, an example has been described in which the control device 10 is applied to the battery charging device 1 (for charging the battery 3). However, the present invention is not limited thereto, and for example, it may also be applied to applications that do not have a battery.

[0105] In addition, a computer system is provided inside the battery charging device 1 described above. Then, the above-described processing procedure of the control unit 17 is stored in a computer-readable recording medium in the form of a program, and the computer reads and executes this program to perform the above-described processing. Here, the computer-readable storage medium refers to a magnetic disk, an optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. In addition, the computer program may be distributed to the computer via a communication line, and the computer that receives this distribution executes this program.

[0106] The present invention can be applied to charging of a battery and the like.

[0107] Reference Signs

[0108] 1 Battery Charging Device

[0109] 2 Generator

[0110] 3 Battery

[0111] 4 Main Switch

[0112] 5 Main Relay

[0113] 6 Main Switch Unit

[0114] 10 Control Device

[0115] 11 Diode

[0116] Capacitors 12, 19, 103, 106

[0117] Voltage conversion unit 13

[0118] Control signal generation unit 14

[0119] Resistors 15, 16, 18, 101, 102, 104, 105

[0120] Control unit 17

[0121] Switching elements 20, 21, 22, 23, 30, 31, 32, 33

[0122] ADC 171

[0123] Memory 172

[0124] CPU 173

Claims

1. A battery charging device, characterized in that, Comprising: A switching element that rectifies the AC voltage generated by the generator by controlling its conduction state and supplies the charging voltage to the battery; A control signal generation unit that outputs a control signal for the switching element based on a control voltage obtained by boosting the power supply voltage output from the battery; And A control unit that controls the control signal to make the switching element in a non-conducting state when the differential voltage representing the control voltage with respect to the voltage of the power line connected to the battery and the battery-side terminal of the switching element is less than or equal to a specified threshold voltage.

2. The battery charging device according to claim 1, wherein: Comprising: A memory for storing a program; And A CPU that executes the program stored in the memory, wherein the control unit is implemented by causing the CPU to execute the program stored in the memory.

3. The battery charging device according to claim 1, wherein: Comprising: An analog-digital converter that detects the voltage of the power line and the control voltage, wherein the control unit calculates the differential voltage based on the voltage of the power line and the control voltage detected by the analog-digital converter.

4. The battery charging device according to claim 1, characterized in that: The specified threshold voltage includes a first threshold voltage and a second threshold voltage higher than the first threshold voltage, The control unit, When the differential voltage is less than or equal to the first threshold voltage, controls the control signal to make the switching element in a non-conducting state, When the differential voltage is higher than the second threshold voltage, controls the conduction state of the switching element to rectify the AC voltage.

5. A control device comprising: A switching element that rectifies the AC voltage generated by the generator by controlling its conduction state and supplies the charging voltage to the battery; And a control signal generation unit that outputs a control signal for the switching element based on a control voltage obtained by boosting the power supply voltage output from the battery, characterized by comprising: A control unit that controls the control signal to make the switching element in a non-conducting state when the differential voltage representing the control voltage with respect to the voltage of the power line connected to the battery and the battery-side terminal of the switching element is less than or equal to a specified threshold voltage.

6. A protection method, comprising: A switching element that rectifies the AC voltage generated by the generator by controlling its conduction state and supplies the charging voltage to the battery; And a control signal generation unit that outputs a control signal for the switching element based on a control voltage obtained by boosting the power supply voltage output from the battery, characterized by including: A control step, in which the control unit controls the control signal to make the switching element in a non-conducting state when the differential voltage representing the control voltage with respect to the voltage of the power line connected to the battery and the battery-side terminal of the switching element is less than or equal to a specified threshold voltage.

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