Overcurrent suppression device

Abstract

This overcurrent suppression device comprises: a switching element that rectifies an AC signal output from a generator to convert the AC signal into DC power; a capacitor that smooths the output voltage of the switching element; a voltage control unit that controls the switching element such that the output voltage is a predetermined set voltage; a current control unit that limits a current flowing to an LED light unit by means of the output voltage so as to obtain a predetermined amount of light when the LED light unit is turned on; and a determination processing unit that determines whether a disconnection has occurred in a connection of the LED light unit on the basis of the current flowing to the LED light unit, and if a disconnection has occurred in the connection of the LED light unit, changes the predetermined set voltage to a second set voltage that is lower than a first set voltage at which the LED light unit can be turned on with the predetermined amount of light, and if no disconnection has occurred in the connection of the LED light unit, changes the predetermined set voltage to the first set voltage.

Description

[Technical Field]

[0001] The present invention relates to an overcurrent suppression device. This application claims priority based on Japanese Patent Application No. 2023-043569, filed on March 17, 2023, the contents of which are incorporated herein by reference. [Background technology]

[0002] In recent years, a technology has become known in which AC power generated by a generator is rectified into DC power for use (see, for example, Patent Document 1). When such a technology is applied to a vehicle such as a motorcycle, the DC power is used to light headlights. In recent years, LEDs (Light Emitting Diodes) have been used for vehicle headlights. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-115071 Summary of the Invention [Problem to be solved by the invention]

[0004] When the above-described conventional technology is used to light a headlight composed of LEDs, in order to obtain a stable light output, it is necessary to maintain a predetermined clamping voltage higher than the VF value (forward voltage value) of the LED while maintaining a current equivalent to the light output from the rectified DC power. Furthermore, for example, when multiple LEDs are connected in series and used in a headlight, a clamping voltage as high as the number of LED stages must be maintained. However, with the above-described conventional technology, for example, if a disconnection occurs in the LED connection, when the headlight is switched from a disconnected state due to the disconnection to a connected state without the disconnection, for example, by switching from high beam to low beam, an overcurrent due to the high clamping voltage flows through the LED.

[0005] The present invention has been made to solve the above problems, and an object of the present invention is to provide an overcurrent suppression device that can suppress overcurrent. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the present invention is a power supply including a switching element that rectifies an AC signal output by a generator and converts it into DC power, a capacitor that smoothes the output voltage of the switching element, a voltage control unit that controls the switching element so that the output voltage becomes a predetermined set voltage, a current control unit that limits the current flowing to the LED light unit depending on the output voltage so that the LED light unit lights up at a predetermined light intensity, and A plurality of lighting modes, Lighting type and By switch Connection Current flows when switched The overcurrent suppression device includes a changeover switch unit that switches the connection of the LED (Light Emitting Diode) of the LED light unit according to a plurality of lighting modes with different paths, and a judgment processing unit that determines whether or not a disconnection has occurred in the connection of the lighting mode selected by the changeover switch unit among the plurality of lighting modes of the LED light unit based on the current flowing in the LED light unit, and if a disconnection has occurred in the connection of the lighting mode selected by the changeover switch unit among the plurality of lighting modes of the LED light unit, changes the predetermined set voltage to a second set voltage that is lower than a first set voltage at which the LED light can be illuminated with the predetermined light intensity, and if the changeover switch unit switches to another lighting mode in which a disconnection has not occurred in the connection of the LED light unit, changes the predetermined set voltage to the first set voltage.

[0007] Furthermore, in one aspect of the present invention, in the above-described overcurrent suppression device, the current control unit has a constant current operation mode that performs constant current control to control the current flowing to the LED light unit so that the current becomes a first current value that allows the LED light unit to light up at the predetermined light intensity, and a standby mode that stops the constant current control and limits the current flowing to the LED light unit to a minute second current value that is smaller than the first current value and that allows for determination of a disconnection in the connection of the LED light unit, and the determination processing unit may change the current control unit to the standby mode if a disconnection has occurred in the connection of the LED light unit, and change the current control unit to the constant current operation mode if no disconnection has occurred in the connection of the LED light unit.

[0008] In addition, one aspect of the present invention is that in the above-mentioned overcurrent suppression device, the current control unit may be configured to start the constant current control with a delay of a predetermined period when transitioning from the standby mode to the constant current operation mode.

[0009] In addition, one aspect of the present invention is that in the above-mentioned overcurrent suppression device, the current control unit may perform the constant current control using a constant current circuit in the constant current operation mode, and may limit the current flowing through the LED light unit to the second current value using a resistive element in the standby mode.

[0010] In addition, one aspect of the present invention is that in the above-mentioned overcurrent suppression device, the LED light unit may include multiple stages of LEDs (Light Emitting Diodes) connected in series, and the second set voltage may be determined based on the forward voltage of the LEDs when a current of the second current value flows through the LED light unit.

[0011] In addition, one aspect of the present invention is that in the above-mentioned overcurrent suppression device, the LED light unit has a plurality of lighting modes with different types of lighting, and is provided with a changeover switch unit that switches the connection of the multiple stages of LEDs depending on the plurality of lighting modes.

[0012] and a determination processing unit that determines whether or not a disconnection has occurred in the connection of the LED light unit based on the current flowing through the LED light unit, and if a disconnection has occurred in the connection of the LED light unit, changes the current control unit to the standby mode. [Effects of the Invention]

[0013] According to the present invention, when a disconnection occurs in the connection of the LED light unit, the determination processing unit changes the set voltage of the voltage control unit to a second set voltage that is lower than the first set voltage at which the LED light unit can be illuminated at a predetermined light intensity. As a result, when, for example, the LED light unit switches from a disconnected state due to a disconnection to a connected state without a disconnection, the overcurrent suppression device reduces the current flowing through the LED light unit by the second set voltage that is lower than the first set voltage, thereby suppressing overcurrent. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a block diagram showing an example of an overcurrent suppression device according to a first embodiment. [Figure 2] FIG. 10 is a diagram illustrating an example of characteristics of a light-emitting diode. [Figure 3]6 is a flowchart showing an example of the operation of the determination processing unit in the first embodiment. [Figure 4] 4A and 4B are diagrams illustrating a state of the overcurrent suppression device according to the first embodiment when a disconnection occurs in the connection of the LED light unit. [Figure 5] 10A and 10B are diagrams illustrating an example of operation when a state in which a disconnection occurs in the connection of the LED light unit of the overcurrent suppression device according to the first embodiment transitions to a state in which no disconnection occurs. [Figure 6] FIG. 4 is a diagram illustrating an example of the effect of the overcurrent suppression device according to the first embodiment. [Figure 7] FIG. 10 is a block diagram showing an example of an overcurrent suppression device according to a second embodiment. [Figure 8] 10 is a flowchart showing an example of the operation of a determination processing unit in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] An overcurrent suppression device according to an embodiment of the present invention will be described below with reference to the drawings.

[0016] [First embodiment] FIG. 1 is a block diagram showing an example of an overcurrent suppression device 1 according to the first embodiment. As shown in FIG. 1, the overcurrent suppression device 1 includes a power supply device 10 and a changeover switch unit 30.

[0017] The overcurrent suppression device 1 is a rush current suppression device that suppresses the current flowing through the LED light unit 20 in a vehicle (such as a motorcycle) that lights up the LED light unit 20 using power generated by a generator 2. Here, the rush current is an overcurrent that flows from a capacitor 12 (described later) to the LED light unit 20 in accordance with the charging voltage of the capacitor 12 when the changeover switch unit 30 is switched.

[0018] 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 of a motorcycle. The generator 2 supplies the AC signal corresponding to the generated power to the thyristor 11 via a power supply line.

[0019] The LED light unit 20 (an example of a lighting device) is, for example, a vehicle headlight (headlamp), and includes multiple stages of LEDs (Light Emitting Diodes) 21 to 24 connected in series. The LED light unit 20 has multiple lighting modes with different lighting types, which can be switched by a changeover switch unit 30. The LED light unit 20 has a low beam mode and a high beam mode.

[0020] LED21 and LED22 are LEDs for the high beam mode and are connected in series between node N3 and node N1. LED21 and LED22 are connected in series in the forward direction from node N3 to node N1.

[0021] LED23 and LED24 are LEDs for the low beam mode, and are connected in series between node N2 and node N3. LED23 and LED24 are connected in series in the forward direction from node N2 to node N3.

[0022] The power supply device 10 supplies a current that enables the LED light unit 20 to light up at a predetermined light intensity, and includes a thyristor 11, a capacitor 12, a current control unit 13, a determination processing unit 14, a voltage control unit 15, and a voltage setting unit (16, 17). The power supply device 10 rectifies the negative voltage portion of the AC voltage generated by the generator 2 and supplies it to the LED light unit 20.

[0023] 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 to the LED light unit 20 as a power source for lighting the LED light unit 20. The thyristor 11 has an anode terminal connected to the LED light unit 20 via a node N1 (output line L1), a cathode terminal connected to the output line of the generator 2, and a gate terminal (control terminal) connected to the signal line of a control signal S1 output by the voltage control unit 15.

[0024] The thyristor 11 rectifies the negative voltage portion of the AC signal output by the generator 2 and supplies it to the LED light unit 20. When the thyristor 11 is turned on (conductive) by a control signal S1 from the voltage control unit 15, it supplies the negative voltage of the AC signal output by the generator 2 to the LED light unit 20, thereby lighting up the LED light unit 20. The thyristor 11 is controlled to be on during the period when the AC signal is negative voltage, and supplies DC power (DC voltage) to the LED light unit 20 by half-wave rectification.

[0025] The capacitor 12 is, for example, an electrolytic capacitor, and is a smoothing capacitor that smoothes the output voltage of the thyristor 11. The capacitor 12 is disposed between the node N1 (output line L1) and the ground line L2. The negative terminal of the electrolytic capacitor of the capacitor 12 is connected to the node N1 (output line L1).

[0026] The current control unit 13 limits the current flowing through the LED light unit 20 (the current flowing from the ground line L2 to the node N2) using the output voltage of the thyristor 11 so that a predetermined amount of light is emitted when the LED light unit 20 is turned on. The current control unit 13 has a constant current operation mode and a standby mode.

[0027] In the constant current operation mode, the current control unit 13 performs constant current control to control the current flowing through the LED light unit 20 to a first current value that allows the LED light unit 20 to light up at a predetermined light intensity. In the standby mode, the current control unit 13 stops the constant current control and limits the current flowing through the LED light unit 20 to a second current value that is a minute current that allows for determination of a disconnection of the LED light unit 20 and is smaller than the first current value. When transitioning from the standby mode to the constant current operation mode, the current control unit 13 starts the constant current control with a predetermined delay.

[0028] The current control unit 13 includes, as a constant current circuit, resistors 131 and 132, PNP transistors 133 and 134, a capacitor 135, and a resistor 136. In the constant current operation mode, the current control unit 13 performs constant current control using the constant current circuit, and in the standby mode, the resistor 131 (resistive element) limits the current flowing through the LED light unit 20 to the second current value described above.

[0029] The resistor 131 is connected between the node N2 and the node N4, and limits the current flowing through the LED light unit 20 to a second current value when the current control unit 13 is in the standby mode. The resistor 132 is connected in series with the resistor 131 between the node N4 and the ground line L2, and converts the current flowing through the current control unit 13 into a potential difference (voltage) across the resistor 132.

[0030] The PNP transistor 133 is connected in parallel with the resistor 131 between the node N2 and the node N4, and limits the current flowing through the LED light unit 20 to a constant current of a first current value when the current control unit 13 is in the constant current operation mode. The PNP transistor 133 has an emitter terminal connected to the node N4, a base terminal (control terminal) connected to the node N5, and a collector terminal connected to the node N2.

[0031] In the constant current operation mode, the PNP transistor 133 is controlled to be in an on state or an off state (non-conducting state) depending on the potential difference (voltage) across the resistor 132 so that the current flowing through the LED light unit 20 becomes a constant current with a first current value. Furthermore, the PNP transistor 133 is fixed to the off state during the standby mode.

[0032] The PNP transistor 134 has an emitter terminal connected to the ground line L2, a base terminal (control terminal) connected to a node N4, and a collector terminal connected to a node N5. In the constant current operation mode, the PNP transistor 134 controls the base current of the PNP transistor 133 in accordance with the potential difference (voltage) across the resistor 132. Furthermore, the PNP transistor 134 is fixed to the off state during the standby mode.

[0033] Capacitor 135 is arranged between node N4 and node N5, and when transitioning from standby mode to constant current operation mode, constant current control is started with a predetermined delay due to a time constant with resistor 136 described later.

[0034] The resistor 136 is connected between the node N5 and the collector terminal of an NPN transistor 143 of the determination processing unit 14, which will be described later. The resistor 136 controls the base current of the PNP transistor 133 together with the PNP transistor 134.

[0035] Voltage control unit 15 controls thyristor 11 so that the output voltage of thyristor 11 becomes a set voltage (predetermined set voltage). Note that the output voltage of thyristor 11 is a negative voltage, and voltage control unit 15 controls thyristor 11 to an OFF state when the absolute value of the output voltage of thyristor 11 is equal to or greater than the set voltage, and controls thyristor 11 to an ON state when the absolute value of the output voltage of thyristor 11 is less than the set voltage.

[0036] The voltage control unit 15 controls the thyristor 11 to the off state when the voltage difference between a node N7, which is obtained by resistively dividing the voltage of the node N1 (output line L1), which is the output voltage of the thyristor 11, by the voltage setting units (16, 17), and the ground line L2, is equal to or greater than a predetermined threshold. The voltage control unit 15 also controls the thyristor 11 to the on state when the voltage difference ΔV between the node N7 and the ground line L2 is less than a predetermined threshold.

[0037] The voltage setting unit 16 is a setting unit that sets a set voltage (second set voltage) when a disconnection occurs in the connection of the LED light unit 20, and includes a resistor 161 and a resistor 162. Resistors 161 and 162 are connected in series between node N1 (output line L1) and ground line L2, and a set voltage (second set voltage) of voltage control unit 15 is set by the resistance ratio between resistors 161 and 162. Resistor 161 is connected between node N1 (output line L1) and node N7, and resistor 162 is connected between node N7 and ground line L2.

[0038] The voltage setting unit 17 is a setting unit that sets a set voltage (first set voltage) when no disconnection occurs in the connection of the LED light unit 20 , and includes a diode 171 and a resistor 172 . The diode 171 has an anode terminal connected to the node N6 of the determination processing unit 14 and a cathode terminal connected to a first end of the resistor 172.

[0039] The resistor 172 has a first end connected to the cathode terminal of the diode 171 and a second end connected to a node N7. When the determination processing unit 14 determines that no disconnection has occurred in the connection of the LED light unit 20, the voltage setting unit 17 changes the voltage difference ΔV between the node N7 and the ground line L2 to a voltage corresponding to the first set voltage by a resistive voltage division configuration consisting of the resistor 172 and the resistors 161 and 162 of the voltage setting unit 16.

[0040] The determination processing unit 14 determines whether or not a disconnection has occurred in the connection of the LED light unit 20 based on the current flowing through the LED light unit 20. If a disconnection has occurred in the connection of the LED light unit 20, the determination processing unit 14 changes the set voltage of the voltage control unit 15 to a second set voltage that is lower than the first set voltage at which the LED light unit 20 can be illuminated with a predetermined light intensity. The determination processing unit 14 changes the set voltage of the voltage control unit 15 to the second set voltage by setting the node N7 using the voltage setting unit 16 described above.

[0041] The second set voltage is determined based on the forward voltage of the LED when a current of the second current value flows through the LED light unit 20. Here, the setting of the second set voltage will be described in detail with reference to FIG.

[0042] FIG. 2 is a diagram showing an example of the characteristics of a light-emitting diode. 2, the horizontal axis represents the forward voltage of a light-emitting diode (LED), and the vertical axis represents the forward current of the LED. Waveform W1 represents the forward current versus forward voltage characteristic of the LED.

[0043] For example, if the forward current of the LEDs required to obtain a predetermined amount of light when the LED light unit 20 (LEDs 21 to 24) is turned on is current IF1, then due to waveform W1, a forward voltage of at least voltage VF1 is required. Therefore, the first set voltage is a voltage value obtained by multiplying voltage VF1 by the number of LED stages and adding a margin voltage (+α) to the voltage.

[0044] Furthermore, as shown by waveform W1, when the forward current of the LED decreases, the forward voltage also decreases. In this embodiment, this characteristic is utilized to determine when a disconnection of the LED light unit 20 (LEDs 21 to 24) is detected (when the current control unit 13 is in standby mode), and the set voltage of the voltage control unit 15 is reduced to a second set voltage based on the forward voltage VF2 so that the forward current reaches a level at which the above-mentioned rush current is not a problem. The second set voltage is a voltage value obtained by multiplying the voltage VF2, which is the forward voltage corresponding to the current IF2, by the number of LED stages and adding a margin voltage (+α).

[0045] Returning to the explanation of FIG. 1, when a disconnection occurs in the connection of the LED light unit 20, the determination processing unit 14 changes the current control unit 13 to the standby mode. Furthermore, the determination processing unit 14 changes the set voltage of the voltage control unit 15 to the first set voltage when there is no disconnection in the connection of the LED light unit 20. Furthermore, the determination processing unit 14 changes the current control unit 13 to a constant current operation mode when there is no disconnection in the connection of the LED light unit 20.

[0046] The determination processing unit 14 also includes a PNP transistor 141 , a resistor 142 , and an NPN transistor 143 . The PNP transistor 141 has an emitter terminal connected to the ground line L2, a base terminal connected to a node N2, and a collector terminal connected to a node N6. The PNP transistor 141 determines whether or not a disconnection has occurred in the connection of the LED light unit 20 depending on whether or not a base current of a predetermined value or more flows through the LED light unit 20.

[0047] For example, when the base current of the PNP transistor 141 is less than a predetermined current value and the transistor is turned off, the PNP transistor 141 determines that a disconnection has occurred in the connection of the LED light unit 20. Also, when the base current of the PNP transistor 141 is more than a predetermined current value and the transistor is turned on, the PNP transistor 141 determines that a disconnection has not occurred in the connection of the LED light unit 20.

[0048] Furthermore, when the PNP transistor 141 is in the on state (when there is no disconnection in the connection of the LED light unit 20), it passes a current through the resistor 172 via the diode 171 of the voltage setting unit 17, and changes the set voltage of the voltage control unit 15 to the first set voltage.

[0049] Furthermore, when the PNP transistor 141 is in the off state (when a break occurs in the connection of the LED light unit 20), it stops the current flowing to the resistor 172 via the diode 171 of the voltage setting unit 17, and changes the set voltage of the voltage control unit 15 to the second set voltage.

[0050] Resistor 142 is disposed between node N6 and the base terminal of NPN transistor 143. The NPN transistor 143 has an emitter terminal connected to the node N2 (output line L1), a base terminal connected to a node N6 via the resistor 142, and a collector terminal connected to the resistor 136 of the current control unit 13.

[0051] For example, when the PNP transistor 141 is on (when no disconnection occurs in the connection of the LED light unit 20), a base current flows through the NPN transistor 143, and the NPN transistor 143 is turned on. When the NPN transistor 143 is turned on, the current control unit 13 is switched to a constant current operation mode.

[0052] For example, when the PNP transistor 141 is in the off state (when a disconnection occurs in the connection of the LED light unit 20), no base current flows through the NPN transistor 143, and the NPN transistor 143 is in the off state. When the NPN transistor 143 is in the off state, the current control unit 13 is switched to the standby mode.

[0053] The changeover switch unit 30 switches the connection of the multiple stages of LEDs according to the multiple lighting modes of the LED light unit 20. The changeover switch unit 30 is, for example, a dimmer switch, and switches between a state in which node N3 is connected to node N1 and a state in which node N3 is connected to node N2. For example, when the changeover switch unit 30 is in a state in which node N3 is connected to node N1, the LED light unit 20 is in high beam mode, and when the changeover switch unit 30 is in a state in which node N3 is connected to node N2, the LED light unit 20 is in low beam mode.

[0054] Next, the operation of the overcurrent suppression device 1 according to this embodiment will be described with reference to the drawings. FIG. 3 is a flowchart showing an example of the operation of the determination processing unit 14 in this embodiment.

[0055] 3, the determination processing unit 14 first determines whether or not a disconnection has occurred in the connection of the LED light unit 20 (step S101). The determination processing unit 14 determines whether or not a disconnection has occurred in the connection of the LED light unit 20, for example, depending on whether or not a base current of the PNP transistor 141 flows that is equal to or greater than a predetermined current value. If a disconnection has occurred in the connection of the LED light unit 20 (step S101: YES), the determination processing unit 14 proceeds to step S102. If a disconnection has not occurred in the connection of the LED light unit 20 (step S101: NO), the determination processing unit 14 proceeds to step S104.

[0056] In step S102, the determination processing unit 14 switches the set voltage of the voltage control unit 15 from set voltage V1 (first set voltage) to a lower set voltage V2 (second set voltage). When the PNP transistor 141 is turned off, the diode 171 of the voltage setting unit 17 is turned off and the voltage setting unit 17 is disabled. This increases the voltage difference ΔV between the node N7 and the ground line L2, and the set voltage of the voltage control unit 15 is switched to set voltage V2 (second set voltage). Note that the predetermined threshold value used to compare the voltage difference ΔV of the voltage control unit 15 is constant, so when the voltage difference ΔV becomes higher relative to the output voltage, the set voltage of the voltage control unit 15 decreases.

[0057] Next, the determination processing unit 14 transitions the current control unit 13 to a standby mode (step S103). When the PNP transistor 141 is turned off, the NPN transistor 143 is turned off, and the determination processing unit 14 transitions the current control unit 13 to the standby mode. After the process of step S103, the determination processing unit 14 returns the process to step S101.

[0058] Furthermore, in step S104, the determination processing unit 14 switches the set voltage of the voltage control unit 15 from set voltage V2 (second set voltage) to a higher set voltage V1 (first set voltage). When the PNP transistor 141 is turned on, the diode 171 of the voltage setting unit 17 is turned on and the voltage setting unit 17 is enabled. This reduces the voltage difference ΔV between the node N7 and the ground line L2, and the set voltage of the voltage control unit 15 is switched to set voltage V1 (first set voltage). Note that the predetermined threshold value used to compare with the voltage difference ΔV of the voltage control unit 15 is constant, so when the voltage difference ΔV becomes lower relative to the output voltage, the set voltage of the voltage control unit 15 increases.

[0059] Next, the determination processing unit 14 transitions the current control unit 13 from the standby mode to the constant current operation mode and starts the constant current control after a predetermined delay (step S105). When the PNP transistor 141 is turned off, the NPN transistor 143 is turned on, and the determination processing unit 14 transitions the current control unit 13 to the constant current operation mode. Note that the start of the constant current control of the current control unit 13 is delayed by the capacitor 135 for a predetermined period. After the processing of step S105, the determination processing unit 14 returns the processing to step S101.

[0060] Next, an example of the operation of the overcurrent suppression device 1 according to this embodiment will be described with reference to FIGS. First, with reference to FIG. 4, the operation of the overcurrent suppression device 1 according to this embodiment when a disconnection occurs in the connection of the LED light unit 20 will be described.

[0061] FIG. 4 is a diagram showing the state of the overcurrent suppression device 1 when a disconnection occurs in the connection of the LED light unit 20. As shown in FIG. The example shown in FIG. 4 shows a state in which the changeover switch is connected to the node N2, the LED light unit 20 is in the high beam mode, and the connection between the LEDs 21 and 22 in the high beam mode is broken.

[0062] 4, because the connection between LED21 and LED22 is broken, no base current flows through the PNP transistor 141, causing it to turn off, and the determination processing unit 14 disables the voltage setting unit 17. Furthermore, because the PNP transistor 141 turns off, the NPN transistor 143 turns off, and the determination processing unit 14 puts the current control unit 13 into standby mode.

[0063] In the standby mode, the current control unit 13 has the PNP transistor 133 and the PNP transistor 134 in an off state. In this case, the voltage difference ΔV between the node N7 and the ground line L2 is set to ΔV1 by the voltage setting unit 16, and the set voltage of the voltage control unit 15 is set to the second set voltage (set voltage V2).

[0064] Next, with reference to FIG. 5, the operation of the overcurrent suppression device 1 according to this embodiment when the state transitions from a state in which a disconnection occurs in the connection of the LED light unit 20 to a state in which no disconnection occurs will be described.

[0065] FIG. 5 is a diagram showing an example of the operation when the overcurrent suppression device 1 according to this embodiment moves from a state in which a disconnection occurs in the connection of the LED light unit 20 to a state in which no disconnection occurs. The example shown in Figure 5 shows a case where the changeover switch is switched from the node N2 to the node N1, and the LED light unit 20 transitions from the high beam mode to the low beam mode, and the connection between LED23 and LED24 in the low beam mode is not broken.

[0066] 5, since the connection between LED23 and LED24 is lit, a base current flows through PNP transistor 141 (step S11), turning it on, and the determination processing unit 14 enables voltage setting unit 17 (step S12). Furthermore, since PNP transistor 141 is turned on, NPN transistor 143 is turned on, and the determination processing unit 14 sets current control unit 13 to a constant current operation mode (step S13).

[0067] When the current control unit 13 shifts from the standby mode to the constant current operation mode, it starts constant current control after a predetermined delay using the capacitor 135. The PNP transistors 134 and 133 of the current control unit 13 are on / off controlled in the constant current operation mode so that the first current value is such that the LED light unit 20 can be illuminated with a predetermined light intensity.

[0068] In this case, the voltage difference ΔV between the node N7 and the ground line L2 is set to ΔV2 by the voltage setting unit 16 (ΔV2<ΔV1), and the set voltage of the voltage control unit 15 is set to the first set voltage (set voltage V1).

[0069] Next, the effect of the overcurrent suppression device 1 according to this embodiment will be described with reference to Fig. 6. Fig. 6 is a diagram showing an example of the effect of the overcurrent suppression device 1 according to this embodiment. 6, waveform W2 represents the output voltage of thyristor 11 in overcurrent suppression device 1 of this embodiment, and waveform W3 represents the output voltage of thyristor 11 in the prior art. Furthermore, waveform W4 represents the current flowing through LED light unit 20 in overcurrent suppression device 1 of this embodiment, and waveform W5 represents the current flowing through LED light unit 20 in the prior art. The horizontal axis indicates time.

[0070] The voltages of the waveforms W2 and W3 are the potential difference across the capacitor 12, and are the output voltages of the thyristor 11. The voltages of the waveforms W2 and W3 are negative voltages.

[0071] Also, at time T1 in FIG. 6, an example is shown in which the changeover switch unit 30 is switched from a disconnection state of the LED light unit 20 to a state in which no disconnection occurs. Before time T1, in the overcurrent suppression device 1 according to this embodiment, the output voltage (waveform W2) is switched to the second set voltage, and therefore drops by the voltage VLow compared to the conventional technique of waveform W3.

[0072] As a result, after time T1, the current flowing through the LED light unit 20 in this embodiment can be reduced by the current ILow, as shown by waveform W4, compared to waveform W5 in the prior art. This reduction in current ILow is achieved by the determination processing unit 14 lowering the set voltage of the voltage control unit 15 to the second set voltage and putting the current control unit 13 into standby mode when it detects a disconnection in the LED light unit 20. In other words, the overcurrent suppression device 1 according to this embodiment can reduce rush current (overcurrent).

[0073] As described above, the overcurrent suppression device 1 according to this embodiment includes a thyristor 11 (switching element), a capacitor 12, a voltage control unit 15, a current control unit 13, and a determination processing unit 14. The thyristor 11 rectifies an AC signal output by the generator 2 and converts it into DC power. The capacitor 12 smoothes the output voltage of the thyristor 11. The voltage control unit 15 controls the thyristor 11 so that the output voltage of the thyristor 11 becomes a predetermined set voltage. The current control unit 13 limits the current flowing through the LED light unit 20 based on the output voltage so that the LED light unit 20 emits a predetermined amount of light when turned on. The determination processing unit 14 determines whether or not a disconnection has occurred in the connection of the LED light unit 20 based on the current flowing through the LED light unit 20. If a disconnection has occurred in the connection of the LED light unit 20, the determination processing unit 14 changes the predetermined set voltage to a second set voltage that is lower than the first set voltage and enables the LED light unit 20 to emit a predetermined amount of light. If no disconnection has occurred in the connection of the LED light unit 20, the determination processing unit 14 changes the predetermined set voltage to the first set voltage.

[0074] As a result, in the overcurrent suppression device 1 according to this embodiment, when the connection of the LED light unit 20 switches from a disconnected disconnected state to a connected state without disconnection, the second set voltage lower than the first set voltage reduces the current that instantaneously flows through the LED light unit 20, thereby suppressing overcurrent (rush current) (see Figure 6).

[0075] In this embodiment, the current control unit 13 has a constant current operation mode and a standby mode. In the constant current operation mode, the current control unit 13 performs constant current control, which controls the current flowing through the LED light unit 20 to a first current value that allows the LED light unit 20 to emit a predetermined amount of light. In the standby mode, the current control unit 13 stops the constant current control and limits the current flowing through the LED light unit 20 to a second current value that is a minute current that allows for determining whether or not there is a disconnection in the LED light unit 20 and is smaller than the first current value. The determination processing unit 14 switches the current control unit 13 to the standby mode if there is a disconnection in the LED light unit 20, and switches the current control unit 13 to the constant current operation mode if there is no disconnection in the LED light unit 20.

[0076] As a result, the overcurrent suppression device 1 of this embodiment changes the current control unit 13 to standby mode when there is a break in the connection of the LED light unit 20, and the current control unit 13 can prevent the capacitor 12 from being overcharged and the output voltage (voltage of the capacitor 12) from becoming high, thereby further reducing the overcurrent (rush current) that instantaneously flows through the LED light unit 20 when switching to a connection state without a break.

[0077] In this embodiment, when the standby mode is switched to the constant current operation mode, the current control unit 13 starts the constant current control with a delay of a predetermined period. As a result, the overcurrent suppression device 1 according to this embodiment starts constant current control with a delay of a predetermined period, thereby further reducing the overcurrent (rush current) flowing through the LED light unit 20 when switching to a connection state without a disconnection.

[0078] In addition, in this embodiment, the current control unit 13 performs constant current control using a constant current circuit in the constant current operation mode, and limits the current flowing through the LED light unit 20 to a second current value using a resistive element (resistor 131) in the standby mode.

[0079] As a result, the overcurrent suppression device 1 according to this embodiment can switch between the first current value in the constant current operation mode and the second current value in the standby mode with a simple configuration using a resistive element.

[0080] In this embodiment, the LED light unit 20 includes multiple stages of LEDs (LEDs 21 to 24) connected in series. The second set voltage is determined based on the forward voltage of the LEDs when a current of the second current value flows through the LED light unit 20.

[0081] As a result, the overcurrent suppression device 1 according to this embodiment can appropriately determine whether or not a disconnection has occurred in the connection of the LED light unit 20 based on the current flowing through the LED light unit 20.

[0082] In this embodiment, the LED light unit 20 has a plurality of lighting modes (high beam mode, low beam mode) with different lighting types. The overcurrent suppression device 1 includes a changeover switch unit 30 that switches the connection of the LEDs in multiple stages according to the plurality of lighting modes.

[0083] As a result, the overcurrent suppression device 1 according to this embodiment can suppress the overcurrent (rush current) flowing through the LED light unit 20 in response to a plurality of lighting modes (high beam mode, low beam mode).

[0084] [Second embodiment] Next, an overcurrent suppression device 1a according to a second embodiment will be described with reference to the drawings. FIG. 7 is a block diagram showing an example of an overcurrent suppression device 1a according to the second embodiment.

[0085] 7, the overcurrent suppression device 1a includes a power supply device 10a and a changeover switch unit 30. The power supply device 10a includes a thyristor 11, a capacitor 12, a current control unit 13, a determination processing unit 14a, a voltage control unit 15, and a voltage setting unit 16a.

[0086] In this embodiment, a modified example will be described in which the overcurrent suppression device 1a does not include the voltage setting unit 17, and the set voltage of the voltage control unit 15 is fixed to the first set voltage and is not switched to the second set voltage. In FIG. 7, the same components as those in FIG. 1 are given the same reference numerals and the description thereof will be omitted.

[0087] The determination processing unit 14a determines whether or not a disconnection has occurred in the connection of the LED light unit 20 based on the current flowing through the LED light unit 20. If a disconnection has occurred in the connection of the LED light unit 20, the determination processing unit 14a changes the current control unit 13 to a standby mode. Furthermore, if no disconnection has occurred in the connection of the LED light unit 20, the determination processing unit 14a changes the current control unit 13 to the constant current operation mode.

[0088] Unlike the judgment processing unit 14 of the first embodiment, the judgment processing unit 14a does not execute the process of changing the set voltage of the voltage control unit 15 to a second set voltage that is lower than the first set voltage at which the LED light unit 20 can be lit with a predetermined light intensity when a break occurs in the connection of the LED light unit 20.

[0089] Furthermore, in this embodiment, the power supply device 10a does not include the voltage setting unit 17. Instead, the power supply device 10a includes a voltage setting unit 16a. The voltage setting unit 16a includes a resistor 161 and a resistor 162, and sets the set voltage of the voltage control unit 15 to the first set voltage in the first embodiment by voltage division between the resistors 161 and 162.

[0090] In this embodiment, the current control unit 13 has a constant current operation mode and a standby mode, and when transitioning from the standby mode to the constant current operation mode, starts constant current control with a predetermined delay. In the constant current operation mode, the current control unit 13 performs constant current control by controlling the current flowing to the LED light unit 20 using the output voltage so that the current becomes a first current value that allows the LED light unit 20 to emit a predetermined amount of light. In the standby mode, the current control unit 13 stops the constant current control and limits the current flowing to the LED light unit 20 to a second current value that is a minute current that allows detection of a disconnection in the LED light unit 20 and is smaller than the first current value.

[0091] Next, the operation of the overcurrent suppression device 1a according to this embodiment will be described with reference to the drawings. FIG. 8 is a flowchart showing an example of the operation of the determination processing unit 14a in this embodiment.

[0092] 8, the determination processing unit 14a first determines whether or not a disconnection has occurred in the connection of the LED light unit 20 (step S201). The determination processing unit 14a determines whether or not a disconnection has occurred in the connection of the LED light unit 20, for example, depending on whether or not a base current of the PNP transistor 141 flows that is equal to or greater than a predetermined current value. If a disconnection has occurred in the connection of the LED light unit 20 (step S201: YES), the determination processing unit 14a proceeds to step S202. If a disconnection has not occurred in the connection of the LED light unit 20 (step S201: NO), the determination processing unit 14a proceeds to step S203.

[0093] In step S202, the determination processing unit 14a transitions the current control unit 13 to a standby mode. When the PNP transistor 141 is turned off, the NPN transistor 143 is turned off, and the determination processing unit 14a transitions the current control unit 13 to the standby mode. After the process of step S202, the determination processing unit 14a returns the process to step S201.

[0094] Furthermore, in step S103, the determination processing unit 14a transitions the current control unit 13 from standby mode to constant current operation mode and starts constant current control after a predetermined delay. When the PNP transistor 141 is turned off, the NPN transistor 143 is turned on, and the determination processing unit 14a transitions the current control unit 13 to the constant current operation mode. Note that the start of constant current control in the current control unit 13 is delayed by the capacitor 135 for a predetermined period. After processing in step S203, the determination processing unit 14a returns the processing to step S201.

[0095] As described above, the overcurrent suppression device 1a according to this embodiment includes the thyristor 11 (switching element), the capacitor 12, the voltage control unit 15, and the determination processing unit 14a. The thyristor 11 rectifies the AC signal output by the generator 2 and converts it into DC power. The capacitor 12 smoothes the output voltage of the thyristor 11. The voltage control unit 15 controls the thyristor 11 so that the output voltage becomes a predetermined set voltage. The current control unit 13 has a constant current operation mode and a standby mode, and when transitioning from the standby mode to the constant current operation mode, starts constant current control with a predetermined delay. In the constant current operation mode, the current control unit 13 performs constant current control, which controls the current flowing through the LED light unit 20 using the output voltage so that the current becomes a first current value that allows the LED light unit 20 to emit a predetermined amount of light. In the standby mode, the current control unit 13 stops constant current control and limits the current flowing through the LED light unit 20 to a second current value that is a minute current that is smaller than the first current value and that allows for determination of a disconnection in the connection of the LED light unit 20. The determination processing unit 14a determines whether or not a disconnection has occurred in the connection of the LED light unit 20 based on the current flowing through the LED light unit 20. If a disconnection has occurred in the connection of the LED light unit 20, the determination processing unit 14a changes the current control unit 13 to the standby mode, and if no disconnection has occurred in the connection of the LED light unit 20, the determination processing unit 14a changes the current control unit 13 to the constant current operation mode.

[0096] As a result, when a disconnection occurs in the connection of the LED light unit 20, the overcurrent suppression device 1a according to this embodiment switches the current control unit 13 to standby mode and limits the current flowing through the LED light unit 20 to a second current value, which is a minute current that can determine whether the connection of the LED light unit 20 is disconnected. Furthermore, when switching from standby mode to constant current operation mode, the current control unit 13 starts constant current control with a predetermined delay. As a result, the overcurrent suppression device 1a according to this embodiment can reduce the overcurrent (rush current) flowing through the LED light unit 20 when switching to a connection state without a disconnection. Therefore, the overcurrent suppression device 1a according to this embodiment can suppress the overcurrent (rush current).

[0097] The present invention is not limited to the above-described embodiments, and can be modified within the scope of the present invention. For example, in each of the above embodiments, 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.

[0098] In addition, in each of the above embodiments, an example has been described in which the negative voltage portion generated by the generator 2 is used to light the LED light unit 20, but this is not limited to this, and a positive voltage may also be used.

[0099] Furthermore, in each of the above embodiments, an example has been described in which the current control unit 13 is equipped with a constant current circuit, but this is not limited to this, and for example, the current may be limited by a resistive element instead of a constant current circuit.

[0100] Furthermore, in each of the above embodiments, the LED light unit 20 is described as a vehicle headlight, but the present invention is not limited to this and may be applied to other lighting devices such as a tail lamp, for example.

[0101] In addition, in each of the above embodiments, the LED light unit 20 includes LEDs 21 to 24, and two rows of LEDs are lit in each of the high beam mode and the low beam mode, but this is not limiting. One row or three or more rows of LEDs may be lit in each of the high beam mode and the low beam mode, or different numbers of rows of LEDs may be lit in each of the high beam mode and the low beam mode.

[0102] Furthermore, in each of the above embodiments, the generator 2 has been described as a single-phase magneto AC generator, but this is not limited to this and the generator may be a generator that outputs AC signals of multiple phases (e.g., three phases), or may be another generator.

[0103] In the first embodiment, the voltage set by the voltage control unit 15 is switched between the first set voltage and the second set voltage by changing the ratio of the resistive voltage division of the output voltage (the voltage of the capacitor 12), but the present invention is not limited to this. For example, instead of changing the ratio of the resistive voltage division, the voltage control unit 15 may change the setting of an internally set threshold voltage (predetermined threshold).

[0104] In each of the above embodiments, the processing of the determination processing unit 14 (14a) and the voltage control unit 15 may be realized by software processing or by hardware processing such as an electronic circuit. That is, the determination processing unit 14 (14a) and the voltage control unit 15 may be realized by circuit means or by software processing that causes a CPU (Central Processing Unit) to execute a program.

[0105] In each of the above embodiments, some or all of the functions of the power supply device 10 (10a) may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each of the above functions may be individually implemented as a processor, or some or all of the functions may be integrated into a processor.

[0106] 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]

[0107] 1, 1a Overcurrent suppressor 2. Generator 10, 10a power supply 11 Thyristor 12, 135 capacitor 13 Current control section 14, 14a Judgment processing unit 15 Voltage control section 16, 16a, 17 Voltage setting section 20 LED light section 21, 22, 23, 24 LEDs 30 Changeover switch section 131, 132, 136, 142, 161, 162, 172 Resistors 133, 134, 141 PNP transistors 143 NPN transistor 171 Diode

Claims

1. a switching element that rectifies the AC signal output by the generator and converts it into DC power; a capacitor for smoothing the output voltage of the switching element; a voltage control unit that controls the switching element so that the output voltage becomes a predetermined set voltage; a current control unit that controls the current flowing through the LED light unit by the output voltage so that the LED light unit has a predetermined light intensity when turned on; a changeover switch unit that switches connections of LEDs (Light Emitting Diodes) included in the LED light unit according to a plurality of lighting modes of the LED light unit, the lighting modes being different in terms of the type of lighting and the paths through which current flows by switching the connection using a switch; a determination processing unit that determines whether or not a disconnection has occurred in a connection of the lighting mode selected by the selector switch unit among the plurality of lighting modes of the LED light unit based on a current flowing in the LED light unit, and when a disconnection has occurred in a connection of the lighting mode selected by the selector switch unit among the plurality of lighting modes of the LED light unit, changes the predetermined set voltage to a second set voltage that is lower than a first set voltage at which the LED light can be illuminated with the predetermined light amount, and when the LED light unit is switched by the selector switch unit to another lighting mode in which a disconnection has not occurred in a connection of the LED light unit, changes the predetermined set voltage to the first set voltage; An overcurrent suppression device comprising:

2. The current control unit a constant current operation mode in which a constant current control is performed to control the current flowing through the LED light unit so that the current becomes a first current value that allows the LED light unit to be lit with the predetermined light amount; a standby mode in which the constant current control is stopped and the current flowing to the LED light unit is limited to a second current value that is a minute current that is smaller than the first current value and that allows for determination of disconnection of the connection of the LED light unit; and The determination processing unit When a disconnection occurs in the connection of the lighting mode selected by the selector switch unit among the plurality of lighting modes of the LED light unit, the current control unit is changed to the standby mode, When the changeover switch unit switches to another lighting mode in which no disconnection occurs in the connection, the current control unit changes to the constant current operation mode. The overcurrent suppression device according to claim 1 .

3. The current control unit When the standby mode is switched to the constant current operation mode, the constant current control is started with a delay of a predetermined period. The overcurrent suppression device according to claim 2 .

4. The current control unit In the constant current operation mode, the constant current control is performed by a constant current circuit; In the standby mode, a resistive element limits the current flowing through the LED light unit to the second current value. The overcurrent suppression device according to claim 3 .

5. The LED light unit includes a plurality of stages of the LEDs connected in series, The second set voltage is determined based on the forward voltage of the LED when a current of the second current value flows through the LED light unit. The overcurrent suppression device according to any one of claims 2 to 4.

6. a switching element that rectifies the AC signal output by the generator and converts it into DC power; a capacitor for smoothing the output voltage of the switching element; a voltage control unit that controls the switching element so that the output voltage becomes a predetermined set voltage; a current control unit that controls the current flowing through the LED light unit by the output voltage so that the LED light unit has a predetermined light intensity when turned on; a determination processing unit that determines whether or not a disconnection has occurred in the connection of the LED light unit based on a current flowing in the LED light unit, and if a disconnection has occurred in the connection of the LED light unit, changes the predetermined set voltage to a second set voltage that is lower than a first set voltage at which the LED light unit can be illuminated with the predetermined light amount, and if a disconnection has not occurred in the connection of the LED light unit, changes the predetermined set voltage to the first set voltage; Equipped with The current control unit a constant current operation mode in which a constant current control is performed to control the current flowing through the LED light unit so that the current becomes a first current value that allows the LED light unit to be lit with the predetermined light amount; a standby mode in which the constant current control is stopped and the current flowing to the LED light unit is limited to a second current value that is a minute current that is smaller than the first current value and that allows for determination of disconnection of the connection of the LED light unit; and The determination processing unit When a disconnection occurs in the connection of the LED light unit, the current control unit is changed to the standby mode, If no disconnection occurs in the connection of the LED light unit, the current control unit is changed to the constant current operation mode, The current control unit In the constant current operation mode, the constant current control is performed by a constant current circuit; In the standby mode, a resistive element limits the current flowing through the LED light unit to the second current value. Overcurrent suppression device.

7. a switching element that rectifies the AC signal output by the generator and converts it into DC power; a capacitor for smoothing the output voltage of the switching element; a voltage control unit that controls the switching element so that the output voltage becomes a predetermined set voltage; a current control unit having a constant current operation mode that performs constant current control by controlling the current flowing to the LED light unit using the output voltage so that the current becomes a first current value that allows the LED light unit to light up with the predetermined light amount, and a standby mode that stops the constant current control and limits the current flowing to the LED light unit to a second current value that is a minute current that is smaller than the first current value and allows for determination of a disconnection of the LED light unit, and that starts the constant current control with a delay of a predetermined period when transitioning from the standby mode to the constant current operation mode; a determination processing unit that determines whether or not a disconnection has occurred in the connection of the LED light unit based on the current flowing in the LED light unit, and changes the current control unit to the standby mode if a disconnection has occurred in the connection of the LED light unit, and changes the current control unit to the constant current operation mode if a disconnection has not occurred in the connection of the LED light unit; Equipped with an overcurrent suppression device.

Images