JP5874052B2 - Power supply device, lighting device, lamp, vehicle - Google Patents

Description

  The present invention relates to a power supply device, a lighting device, a lamp, and a vehicle that convert electric power from a DC power supply and supply the same to a load.

  This type of power supply device is used for a lamp such as a headlamp in a vehicle, for example, and supplies power to a load composed of a light source such as a light emitting diode (LED) (for example, see Patent Document 1). The power supply device described in Patent Document 1 includes a DC-DC conversion circuit (flyback converter) in which a primary-side current path and a secondary-side current path are separated by a transformer, and an output of the DC-DC conversion circuit. An output abnormal state determination means for determining whether or not the voltage is abnormal is provided.

  In this type of power supply device, the output line of the power supply device comes into contact with the ground (negative electrode side) of the DC power supply (battery) due to biting or deterioration of the wiring, incorrect wiring, etc. There is a possibility of contact with the wire (positive electrode side). The power supply device described in Patent Document 1 stops the output operation of the DC-DC conversion circuit when the output abnormal state determination means determines that the output is abnormal even when such a ground fault or power fault occurs. Circuit protection is possible.

JP 2009-284721 A

  However, in the power supply device described in Patent Document 1, although a circuit can be protected when a ground fault or a power fault occurs in the output, since a transformer is used for the DC-DC conversion circuit, it is difficult to reduce the cost. There is.

  The present invention has been made in view of the above reasons, and there is provided a power supply device, a lighting device, a lamp, and a vehicle that do not break a circuit even when a ground fault or a power fault occurs in an output without using a transformer. The purpose is to provide.

A power supply device according to the present invention includes a series circuit of a switching element and a first inductor that are alternately turned on and off alternately. The switching element is connected between a pair of input terminals to which a DC power supply is connected. And the second inductor is connected to a cathode side of the rectifying element between a pair of output terminals to which a load is connected. A first capacitor connected between the second series circuit connected to be connected to the one end of the first inductor and the cathode of the rectifying element; further comprising a second capacitor connected between the anode of the other end and the rectifying element of the first inductor, and a resistor connected in parallel with said second capacitor And features.

A power supply device according to the present invention includes a series circuit of a switching element and a first inductor that are alternately turned on and off alternately. The switching element is connected between a pair of input terminals to which a DC power supply is connected. And the second inductor is connected to a cathode side of the rectifying element between a pair of output terminals to which a load is connected. A first capacitor connected between the second series circuit connected to be connected to the one end of the first inductor and the cathode of the rectifying element; and a second capacitor connected between the anode of the other end and the rectifying element of the first inductor, the second capacitor, compared with the first capacitor Wherein the capacitance is large.

A power supply device according to the present invention includes a series circuit of a switching element and a first inductor that are alternately turned on and off alternately. The switching element is connected between a pair of input terminals to which a DC power supply is connected. And the second inductor is connected to a cathode side of the rectifying element between a pair of output terminals to which a load is connected. A first capacitor connected between the second series circuit connected to be connected to the one end of the first inductor and the cathode of the rectifying element; the first inductor and the other end with a second capacitor connected between the anode of the rectifier element, the control circuit for controlling the switching operation of the switching element Wherein the control circuit monitors the potential of the connection point between the second capacitor and the rectifier element, the potential is characterized by stopping the switching operation of the switching element below a predetermined threshold .

A power supply device according to the present invention includes a series circuit of a switching element and a first inductor that are alternately turned on and off alternately. The switching element is connected between a pair of input terminals to which a DC power supply is connected. And the second inductor is connected to a cathode side of the rectifying element between a pair of output terminals to which a load is connected. A first capacitor connected between the second series circuit connected to be connected to the one end of the first inductor and the cathode of the rectifying element; the first inductor and the other end with a second capacitor connected between the anode of the rectifier element, the control circuit for controlling the switching operation of the switching element The magnitude of the output current flowing from the output terminal to the load is monitored by monitoring the voltage across the detection resistor inserted between the output terminal and the connection point of the rectifying element in the second capacitor. e Bei a current measuring unit for measuring, the control circuit, the measurement value of the current measuring unit has to control the switching element to a predetermined reference value, and said second capacitor and said rectifying element When the period during which the potential at the connection point is lower than a predetermined threshold value continues for a predetermined time, the switching element is kept in a stopped state of the switching operation .

  A lighting device of the present invention includes the power supply device described above, and a light source load using a semiconductor light emitting element is connected to the output terminal as the load, and the light source load is turned on by supplying power to the light source load. And

  The lamp of the present invention is characterized in that the lamp is provided with the lighting device.

  A vehicle according to the present invention includes the above-described lamp.

  The present invention has an advantage that without using a transformer, it is possible to realize a configuration in which a circuit is not broken even when a ground fault or a power fault occurs in the output.

1 is a schematic circuit diagram illustrating a configuration of a power supply device according to a first embodiment. 1 is a schematic circuit diagram illustrating a basic configuration of a power supply device according to a first embodiment. FIG. 5 is a diagram for explaining the operation of the power supply device according to the first embodiment. FIG. 3 is a waveform diagram for explaining the operation of the power supply device according to the first embodiment. It is explanatory drawing which shows the state which the ground fault and the power fault generate | occur | produced in the power supply device which concerns on Embodiment 1. FIG. It is a wave form diagram explaining the operation | movement at the time of the occurrence of a ground fault of the power supply device which concerns on Embodiment 1. FIG. It is a wave form diagram explaining the operation | movement at the time of the occurrence of a ground fault of the power supply device which concerns on Embodiment 1. FIG. FIG. 3 is a schematic circuit diagram illustrating a configuration of a power supply device according to a second embodiment. FIG. 6 is a waveform diagram for explaining the operation of the power supply device according to the second embodiment. It is a schematic circuit diagram which shows the structure of the lighting device using the power supply device which concerns on Embodiment 2. FIG. It is sectional drawing of the lamp using the power supply device which concerns on Embodiment 2. FIG. It is an external appearance perspective view of the vehicle using the power supply device which concerns on Embodiment 2. FIG.

(Embodiment 1)
In the present embodiment, a power supply device that is used in a vehicle and converts electric power from a DC power supply (for example, a 12V vehicle-mounted battery) and supplies it to a load (for example, a light emitting diode) will be described as an example.

  As shown in FIG. 2, the power supply device 1 of this embodiment includes a pair of input terminals (power connection terminals) 21 and 22 to which a DC power supply 2 (see FIG. 1) is connected, and a load 3 (see FIG. 1). A pair of output terminals (load connection terminals) 31 and 32 to be connected are provided. FIG. 2 is a schematic circuit diagram showing a basic configuration of the power supply device 1, and FIG. 1 is a schematic circuit diagram of the power supply device 1 embodying the basic configuration.

  The power supply device 1 includes a first series circuit 11 formed of a series circuit of a switching element S1 and a first inductor L1 between input terminals 21 and 22, and a second inductor between output terminals 31 and 32. A second series circuit 12 including a series circuit of L2 and a diode D1 is provided.

  Here, the first series circuit 11 connects the switching element S1 to the first input terminal (positive input terminal) 21 on the positive electrode (plus) side of the DC power supply 2 and connects the first inductor L1 to the DC power supply 2. Is connected to a second input terminal (negative input terminal) 22 which is the negative (minus) side of the terminal. That is, one end of the switching element S1 and the first inductor L1 are connected to each other, the other end of the switching element S1 is connected to the first input end 21, and the other end of the first inductor L1 is the second input. Connected to the end 22.

  In the second series circuit 12, the second inductor L <b> 2 is connected to the first output end 31, and the anode of the diode D <b> 1 is connected to the second output end 32. That is, one end of the second inductor L2 is connected to the cathode of the diode D1, the other end of the second inductor L2 is connected to the first output end 31, and the anode of the diode D1 is connected to the second output end 32. It is connected. The first output end 31 is connected to one end of the load 3 on the high potential side, and the second output end 32 is connected to the other end of the load 3 on the low potential side.

  Further, the power supply device 1 includes a first capacitor C1 and a second capacitor C2 connected between the first series circuit 11 and the second series circuit 12. The first capacitor C1 is connected between one end of the first inductor L1 (connection point with the switching element S1) and the cathode of the diode D1 (connection point with the second inductor L2). The second capacitor C2 is connected between the other end (second input end 22) of the first inductor L1 and the anode (second output end 32) of the diode D1.

Further, the power supply device 1 of the present embodiment includes a control circuit 13 that controls the on / off operation of the switching element S1 and a third capacitor C3 connected between the pair of output terminals 31 and 32 as shown in FIG. And. The third capacitor C <b> 3 is provided for smoothing, and is connected in parallel with the second series circuit 12 between the pair of output terminals 31 and 32. Here, as the switching element S1, a voltage-driven MOS-FET (Metal-Oxide-Semiconductor) is used. Field-Effect Transistor) is used, and the control circuit 13 is connected to the gate terminal of the switching element S1. The switching element S1 is not limited to the MOS-FET, and may be other elements. The rectifying element is not limited to the diode D1, and may be other elements.

The control circuit 13 outputs a drive signal having a frequency of several hundred kHz to the switching element S1 from the viewpoint of circuit component miniaturization, and turns the switching element S1 on and off at a high frequency. Here, the control circuit 13 is a PWM (Pulse Width) that changes the on-duty of the switching element S1 with a fixed frequency. The on / off operation of the switching element S1 is controlled by (Modulation) control. Specifically, the control circuit 13 monitors the input current and the input voltage to the power supply device 1 and controls the on / off operation of the switching element S1 so that these values become predetermined values, thereby achieving a desired output. Get. Alternatively, the control circuit 13 may be configured to use, for example, a photocoupler, monitor the output current and output voltage from the power supply device 1, and directly control these values to be predetermined values.

  Next, in the power supply device 1 having the above-described configuration, a basic operation when the switching element S1 is alternately turned on and off by the control circuit 13 will be described with reference to FIGS. In FIG. 3, the operation when the switching element S1 is on is shown in (a), and the operation when it is off is shown in (b). In FIG. 3, the “+” mark represents the polarity of the voltage generated in the first to third capacitors C1 to C3 (“+” is the positive side) (the same applies to FIG. 5 and subsequent figures). In FIG. 4, (a) is the on / off state of the switching element S1, (b) is the current I1, (c) is the current I2, (d) is the input voltage V10, and (e) is the voltage with the horizontal axis as the time axis. (V2−V1) and (f) represent the voltage (−V3), and (g) represents the output voltage V11.

  Here, “V10” in FIG. 3 and FIG. 4 indicates an input voltage to the power supply device 1, “V11” indicates an output voltage from the power supply device 1, “I1” indicates a current flowing through the first inductor L1, “ “I2” indicates the current flowing through the second inductor L2 (the same applies to FIG. 5 and subsequent figures). In FIG. 3, “P1” is a connection point between the switching element S1 and the inductor L1 of the capacitor C1, “P2” is a connection point between the inductor L2 of the capacitor C1 and the diode D1, and “P3” is a connection point between the diode D1 of the capacitor C2. Connection points are shown (the same applies to FIG. 5 and subsequent figures). In FIG. 4, “V1” indicates the potential at point P1 (ground reference), “V2” indicates the potential at point P2 (ground reference), and “V3” indicates the voltage at point P3 (ground reference) (also from FIG. 5 onward). The same).

  First, when the switching element S1 is turned on at time t0 (see FIG. 4), the current I1 flowing through the first inductor L1 increases with the passage of time during the on-period (t0 to t1) of the switching element S1. Energy is stored from 2 to the first inductor L1.

  At this time (t0 to t1), the energy stored in the first and second capacitors C1 and C2 in the off period of the switching element S1 before the time t0 is converted into the second inductor L2 and the load (third To the capacitor C3) 3. Further, at this time, the current I2 flowing through the second inductor L2 in response to the energy stored in the first and second capacitors C1 and C2 increases with time, and energy is stored in the second inductor L2. It is done. Thereby, the both-ends voltage (V2-V1) of the 1st capacitor | condenser C1 and the both-ends voltage (-V3) of the 2nd capacitor | condenser C2 fall.

  Next, when the switching element S1 is turned off at time t1, the energy stored in the first inductor L1 is transferred to the first and second capacitors C1 and C2 during the off period (t1 to t2) of the switching element S1. It is transmitted via the diode D1. As a result, the voltage across the first capacitor C1 (V2-V1) and the voltage across the second capacitor C2 (-V3) increase, and the current I1 flowing through the first inductor L1 decreases with time. . At this time (t1 to t2), the energy stored in the second inductor L2 is transmitted to the load (third capacitor C3) 3, and the current I2 flowing through the second inductor L2 increases with time. Decrease.

  The power supply device 1 repeats the operation during the on period and the operation during the off period of the switching element S1 as described above even after the time t2, thereby generating voltages and currents as shown in FIG. To supply power. In the present embodiment, the output voltage V11 of the power supply device 1 is smoothed by the third capacitor C3 connected between the output terminals 31 and 32.

  Here, when the capacitances of the first capacitor C1 and the second capacitor C2 are the same, the generated voltage is the same between the first capacitor C1 and the second capacitor C2 from the viewpoint of energy. (A)-(g) has shown the waveform at that time. That is, the voltage (V2−V1) of the first capacitor C1 and the voltage (−V3) of the second capacitor C2 have the same waveform (see FIGS. 4E and 4F). Further, in the circuit configuration of the present embodiment, the value obtained by adding the voltages (V2−V1 and −V3) generated in the first and second capacitors C1 and C2 is substantially the same value as the output voltage V11.

  In the above description, in order to explain the basic operation of the power supply device 1 in an easy-to-understand manner, the currents I1 and I2 flowing through the first and second inductors L1 and L2 continuously flow without becoming zero (currents). The continuous mode was described as an example. The output voltage V11 is also shown as a value completely smoothed by the third capacitor C3 (see FIG. 4G). Actually, depending on the constants of the capacitors C1 and C2 and the inductors L1 and L2, the driving frequency of the switching element S1, or the impedance of the load 3, for example, the pulsations of the currents I1 and I2 increase or become flatter. The basic operation is as described above.

  Next, operations of the power supply device 1 when a ground fault or a power fault occurs in the output of the power supply device 1 will be described in order with reference to FIGS.

  First, as shown by (1) in FIG. 5, when a ground fault occurs when the second output terminal 32 on the low potential side contacts the ground (negative electrode) of the DC power supply 2, the operation of the power supply device 1 is performed. The waveform is as shown in FIG. FIG. 6 shows only portions different from those in FIG. 4, where the horizontal axis is the time axis, (a) is the on / off state of the switching element S1, and (b) is the voltage (V2) of the first capacitor C1. -V1) and (c) represent the voltage (-V3) of the second capacitor C2, and (d) represents the output voltage V11.

  In this case, the potential of the second output terminal 32 is fixed to the ground of the DC power supply 2 due to a ground fault. Therefore, the voltage (−V3) of the second capacitor C2 becomes zero (see FIG. 6C), while the voltage (V2−V1) of the first capacitor C1 increases by that amount (FIG. 6B). reference). In the power supply device 1 of the present embodiment, even when such an abnormality (ground fault) occurs, if necessary, the power supply to the load 3 is supplied by controlling the on / off operation of the switching element S1. It is possible to continue.

  Further, as shown in FIG. 5 (2), when the first output terminal 31 on the high potential side is in contact with the ground of the DC power supply 2 and a ground fault occurs, the operation waveform of the power supply device 1 is shown in FIG. As shown in FIG. FIG. 7 shows only portions different from those in FIG. 4, where the horizontal axis is the time axis, (a) is the on / off state of the switching element S1, and (b) is the voltage (V2) of the first capacitor C1. -V1) and (c) represent the voltage (-V3) of the second capacitor C2, and (d) represents the output voltage V11.

  In this case, the potential of the first output terminal 31 is fixed to the ground of the DC power supply 2 due to a ground fault. Therefore, the voltage (−V3) of the second capacitor C2 becomes a potential determined by the output voltage V11, and the voltage (V2−V1) of the first capacitor C1 becomes substantially zero due to the influence. In the power supply device 1 of the present embodiment, even when such an abnormality (ground fault) occurs, the on / off operation of the switching element S1 is controlled if necessary, as in the case of FIG. 5 (1). By doing so, it is possible to continue power supply to the load 3.

  In addition, when the second output terminal 32 is in contact with the live line (positive electrode) of the DC power source 2 as shown by (3) in FIG. As in the case of the ground fault, the potential of the second output terminal 32 is fixed to the positive potential of the DC power supply 2. In the power supply device 1 of the present embodiment, even when such an abnormality (power fault) occurs, the on / off operation of the switching element S1 is controlled if necessary, as in the case of FIG. 5 (1). By doing so, it is possible to continue power supply to the load 3.

  Similarly, when the first output terminal 31 is in contact with the live line of the DC power supply 2 as shown by (4) in FIG. The potential of the first output terminal 31 is fixed to the positive potential of the DC power supply 2 as in the case of the wire. In the power supply device 1 of the present embodiment, even when such an abnormality (power fault) occurs, the on / off operation of the switching element S1 is controlled if necessary, as in the case of FIG. 5 (1). By doing so, it is possible to continue power supply to the load 3.

  According to the power supply device 1 having the configuration described above, it is possible to continue supplying power to the load 3 without breaking the circuit when a ground fault or a power fault occurs in the output even though no transformer is used. There is an advantage. That is, in the power supply device 1 according to the present embodiment, the input terminals 21 and 22 connected to the DC power supply 2 and the output terminals 31 and 32 connected to the load 3 include a first series circuit 11-a second series. The first and second capacitors C1 and C2 provided between the circuits 12 are cut off in a direct current manner. That is, since the power supply device 1 cuts off the input side and the output side in a DC manner by the first and second capacitors C1 and C2, for example, even if a ground fault or a power fault occurs in the output, Abnormality does not affect the input, and power supply to the load 3 can be continued without breaking the circuit.

  In addition, since the power supply device 1 has the input terminals 21 and 22 and the output terminals 31 and 32 cut off by the capacitors C1 and C2, the circuit configuration is simpler than that in which insulation is performed using a transformer. It can be used, and the cost can be kept low because the transformer is no longer needed.

  Furthermore, since the power supply device 1 of the present embodiment is provided with the second inductor L2 on the output side (first output end 31), the ripple on the current and voltage on the output side can be kept low. Further, according to the present embodiment, the voltage of the DC power source 2 connected to the input terminals 21 and 22 can be boosted or lowered (that is, stepped up or down) to a voltage suitable for the load 3 and supplied.

  In the present embodiment, the case where the first and second capacitors C1 and C2 have the same capacitance has been described as an example. However, the first capacitor C1 and the second capacitor C2 have different capacitances. May be. That is, by sharing the capacitances of the first and second capacitors C1 and C2 with intentionally different values, the voltage sharing between the first capacitor C1 and the second capacitor C2 can be shared from the viewpoint of energy. It is possible to change. For example, by making the capacitance of the second capacitor C2 larger than the capacitance of the first capacitor C1, the potential (V3) of the second output terminal 32 can be brought close to the ground level of the DC power supply 2. it can. Such setting (selection) of the capacitances of the first and second capacitors C1 and C2 is effective, for example, when the output potential is set within a predetermined range for output control.

  Further, regarding the control method of the switching element S1 by the control circuit 13, the fixed frequency PWM control is merely an example, and other methods (for example, frequency control) may be used instead of the PWM control.

(Embodiment 2)
As shown in FIG. 8, the power supply device 1 of the present embodiment is different from the power supply device 1 of the first embodiment in that it includes a first resistor R <b> 1 connected in parallel with the second capacitor C <b> 2. Hereinafter, the same configurations as those of the first embodiment are denoted by common reference numerals, and description thereof is omitted as appropriate.

  That is, in the present embodiment, the power supply device 1 is provided between the other end of the first inductor L1 connected to the second input end 22 and the anode of the diode D1 connected to the second output end 32. And a parallel circuit of a second capacitor C2 and a first resistor R1. In the power supply device 1, the first resistor R1 is connected in parallel with the second capacitor C2, so that the voltage (−V3) of the second capacitor C2 is a value corresponding to the resistance value of the first resistor R1. Can be set. In short, the voltage of the second capacitor C2 can be intentionally set to an arbitrary value by adjusting the value of the first resistor R1.

  FIG. 9 shows an operation waveform of the power supply device 1 when the resistance value of the first resistor R1 is set to be relatively small (for example, 100Ω or less). FIG. 9 shows only portions different from those in FIG. 4, where the horizontal axis is the time axis, (a) is the on / off state of the switching element S1, and (b) is the voltage (V2) of the first capacitor C1. -V1) and (c) represent the voltage (-V3) of the second capacitor C2, and (d) represents the output voltage V11.

  In this case, the voltage (−V3) of the second capacitor C2 is substantially zero (see FIG. 9C), and the voltage (V2−V1) of the first capacitor C1 is the same as described in the first embodiment. It rises by a minute (see FIG. 9B). In this way, by setting the resistance value of the first resistor R1 to be relatively small, for example, for the purpose of simplifying the configuration of the output detection circuit, the potential (V3) of the second output terminal 32 is intentionally DC. The power supply 2 can be brought close to the ground level.

  Conversely, when the resistance value of the first resistor R1 is set to be relatively large (for example, 1 kΩ), the voltage (−V3) of the second capacitor C2 is a voltage that pulsates around several volts.

  In addition, when a constant of the resistor R1 that can cope with an abnormal state of the target output (ground fault or sky fault) is selected, the power supply device 1 may be connected via the resistor R1 when an abnormality occurs depending on an abnormality occurrence mode. Although direct current may flow between the input and output, the circuit will not be broken even in the event of an abnormality. Therefore, the power supply device 1 can adopt a simple circuit configuration as compared with a configuration in which the input and output are insulated by using a transformer, and the cost can be reduced to the extent that the transformer is not necessary.

  In this embodiment, the ripple of the voltage (−V3) of the second capacitor C2 is reduced by making the capacitance of the second capacitor C2 larger than the capacitance of the first capacitor C1. This is effective when it is desired to obtain a voltage close to zero including the ripple.

  Next, a more specific configuration of the power supply device 1 will be described by taking as an example the case where the power supply device 1 of the present embodiment is applied to a lighting device.

  As shown in FIG. 10, the lighting device including the power supply device 1 includes a light source load 30 using a semiconductor light emitting element such as a light emitting diode (LED) connected as a load between a pair of output terminals 31 and 32. By supplying power (constant current) to 30, the light source load 30 is turned on. The light source load 30 includes, for example, a plurality (two in FIG. 10) of LED (light emitting diode) modules 301 and 302 connected in series. Each LED module 301 and 302 includes, for example, four LEDs connected in series. It is composed of a chip (semiconductor light emitting element).

  In addition to the configuration of FIG. 8, the power supply device 1 illustrated in FIG. 10 includes a fourth capacitor C4 connected between the pair of input terminals 21 and 22, and a connection point between the anode connection point of the diode D1 and the third capacitor C3. And a second resistor R <b> 2 connected between the two output terminals 32. The fourth capacitor C4 is for smoothing, and the second resistor R2 is a detection resistor for measuring the magnitude of the output current flowing from the output terminals 31 and 32 to the light source load 39. The power supply device 1 constitutes a lighting device capable of constant current control with a constant output current by a combination of the second resistor R2 serving as a detection resistor and the control circuit 13.

  Hereinafter, a specific configuration of the control circuit 13 will be described with reference to FIG. In FIG. 10, “P4” indicates a connection point between the second resistor R2 and the second output terminal 32.

  The control circuit 13 includes an operational amplifier 131, a capacitor C13, and a differential amplifier circuit 41 configured by resistors R13, R14, R15, and R19, and an error calculation circuit 42 configured by an operational amplifier 132, a capacitor C12, and a resistor R12. Yes.

  In the differential amplifier circuit 41, a parallel circuit of a capacitor C13 and a resistor R13 is connected between the inverting input and output of the operational amplifier 131, and the non-inverting input of the operational amplifier 131 is connected to the ground via the resistor R15. Further, one end of the second resistor R2 (a connection point with the third capacitor C3) is connected to the inverting input of the operational amplifier 131 via the resistor R14, and the second resistor R2 is connected to the non-inverting input of the operational amplifier 131. The other end (P4) is connected via a resistor R19. Thereby, the differential amplifier circuit 41 amplifies the potential difference (difference between the potential V4 at the point P4 and the potential V3 at the point P3) generated between both ends of the second resistor R2, and measures the output current. Configure.

  In the error calculation circuit (configured by proportional integration control) 42, a series circuit of a capacitor C 12 and a resistor R 12 is connected between the inverting input and output of the operational amplifier 132. Further, the output of the differential amplifier circuit 41 (the output of the operational amplifier 131) is connected to the inverting input of the operational amplifier 132, and the first reference voltage Vref1 is applied to the non-inverting input of the operational amplifier 132. Thereby, the error calculation circuit 42 compares the measurement result of the output current with the reference voltage Vref1, and gives the error calculation result to the comparison circuit at the next stage.

  Further, the control circuit 13 includes a comparator circuit composed of a comparator 134 that compares the output of the error calculation circuit 42 (output of the operational amplifier 132) and the output of an oscillator (high frequency oscillation circuit) 133 that outputs a high-frequency triangular wave as an oscillation signal. I have. The comparator 134 generates a drive signal (PWM signal) for the switching element S1 by comparing the output of the error calculation circuit 42 with the oscillation signal from the oscillator 133.

  With the above configuration, the control circuit 13 determines the on-duty of the drive signal for the switching element S1 so that the output (measurement result of the output current) of the differential amplifier circuit 41 is equal to the reference voltage Vref1. The comparator 134 outputs the generated drive signal to the switching element S1 via the first AND circuit 130, so that the control circuit 13 causes the output current of the power supply device 1 to be a constant current. Realize feedback control. Here, the power supply device 1 uses the differential amplifier circuit 41 to detect the output current, detects the value of the current flowing through the current detection resistor R2 even when an abnormality occurs in the output, and this detected value is the reference voltage Vref1. The switching operation by feedback control is performed so that For this reason, it is possible to suppress the occurrence of an excessive current to the light source load 30 or the like when an output abnormality occurs.

  Next, a configuration for detecting an abnormality such as a ground fault or a power fault occurring in the output of the power supply device 1 in the control circuit 13 will be described.

  The control circuit 13 includes an inverting amplifier circuit 43 including an operational amplifier 135, a capacitor C20, and resistors R20, R21, and R22, a comparator 136, and a second AND circuit 137.

  In the inverting amplifier circuit 43, a parallel circuit of a capacitor C20 and a resistor R20 is connected between the inverting input and output of the operational amplifier 135, and the non-inverting input of the operational amplifier 135 is connected to the ground via the resistor R22. Further, a point P3 (a connection point with the diode D1 in the second capacitor C2) is connected to the inverting input of the operational amplifier 135 through a resistor R21, and the output of the operational amplifier 135 is connected to the inverting input of the comparator 136. As a result, the inverting amplifier circuit 43 inverts and amplifies the potential V3 at the point P3 and outputs it to the comparator 136.

  The comparator 136 has the reference voltage Vref2 applied to the non-inverting input. When the output of the inverting amplification circuit 43 (inversion amplification of the potential V3) exceeds the reference voltage Vref2, the output immediately becomes L level. The output of the comparator 136 is input to the second AND circuit 137, and the output of the second AND circuit 137 is input to the first AND circuit 130.

  Therefore, in the control circuit 13, when the output of the comparator 136 becomes L level, the output of the second AND circuit 137 becomes L level, and the first AND circuit 130 also becomes L level. In short, the control circuit 13 monitors the potential V3 at the connection point (P3) between the second capacitor C2 and the diode D1, and when the potential V3 falls below a predetermined threshold, the second and first AND circuits 137 are displayed. , 130 becomes L level. The threshold here is the minimum value that the potential V3 can normally take, and is determined by the reference voltage Vref2. At this time, the control circuit 13 turns off the switching element S1 and stops the switching operation (ON / OFF operation) of the switching element S1.

  The output of the comparator 136 is provided with a state detection circuit 138, and the output of the state detection circuit 138 is also connected to the input of the second AND circuit 137. The state detection circuit 138 maintains the state by changing the output from the H level to the L level when the state where the input from the comparator 136 is at the L level continues for a predetermined time (for example, 5 ms). When the output of the state detection circuit 138 becomes L level, the outputs of the second and first AND circuits 137 and 130 also become L level, and the control circuit 13 turns off the switching element S1 and performs the switching operation of the switching element S1. (ON / OFF operation) is stopped.

  Specifically, the state detection circuit 138 is configured such that the input is continuously at the L level for a predetermined time (maintaining the L level) or the state where the input is changed from the H level to the L level repeatedly occurs for a predetermined time ( H / L repetition), the output is changed to L level, and the state is maintained (latched).

  Here, the operation of the control circuit 13 when a ground fault or a power fault occurs in the output of the power supply device 1 will be described.

  First, when a ground fault occurs in the first output terminal 31, the potential of the output terminal 31 is fixed to the ground of the DC power supply 2, and the potential V3 decreases by the voltage across the third capacitor C3. The potential V3 is below a predetermined threshold value. Therefore, the control circuit 13 detects this abnormality (ground fault) and the output of the comparator 136 changes to L level. As a result, the outputs of the second and first AND circuits 137 and 130 also become L level, and the control circuit 13 turns off the switching element S1 and stops the switching operation of the switching element S1.

  When a ground fault occurs at the second output end 32, the potential at the output end 32 is fixed to the ground of the DC power supply 2. Therefore, the power supply device 1 has a configuration in which the first resistor R1 and the second resistor R2 are substantially connected in parallel, and the first and second resistors R1 are generated by the voltage generated in the third capacitor C3. , R2 flows through the light source load 30 through the parallel circuit. As a result, a voltage corresponding to the combined resistance of the first and second resistors R1 and R2 and the current flowing through the connection point (P3) between the second capacitor C2 and the resistor R2 is generated. Also in this case, if each resistance value of the first and second resistors R1 and R2 and the value of the reference voltage Vref2 are appropriately set, the control circuit 13 detects this abnormality (ground fault). As a result, the output of the comparator 136 changes to the L level. As a result, the outputs of the second and first AND circuits 137 and 130 also become L level, and the control circuit 13 turns off the switching element S1 and stops the switching operation of the switching element S1.

  In addition, when the power supply device 1 is used as a booster circuit, the control circuit 13 can detect an abnormality (a power fault) even when a power fault occurs and can stop the switching operation of the switching element S1. .

  In short, when an abnormality such as a ground fault or a power fault occurs in the output of the power supply device 1, the control circuit 13 detects this abnormality and the output of the comparator 136 changes to the L level, and the second AND circuit. The output of 137 becomes L level, and the first AND circuit 130 also becomes L level. At this time, the control circuit 13 turns off the switching element S1 and stops the switching operation of the switching element S1.

  According to the power supply device 1 of the present embodiment described above, when a ground fault or a power fault occurs in the output, the above configuration detects the abnormality more quickly and stops the switching operation of the switching element S1. Circuit protection can be achieved.

  The control circuit 13 stops the switching operation of the switching element S1 by the state detection circuit 138 when a period during which the potential V3 of the connection point (P3) between the second capacitor C2 and the diode D1 is lower than the threshold value continues for a predetermined time. Maintain state. Therefore, when the state in which the ground fault or the power fault has occurred in the output continues for a predetermined time, the power supply device 1 is maintained in a state where the switching element S1 has stopped operating, and the circuit protection is more reliably achieved. be able to.

  Next, the control circuit 13 monitors the output voltage of the power supply device 1 to explain voltage control when the output is open, and circuit protection when the output open state and the output short-circuit state continuously occur. To do.

  The control circuit 13 includes a non-inverting amplifier circuit 44 including an operational amplifier 139, a capacitor C14, and resistors R16, R17, and R18, and three comparators 140, 141, and 143 connected to the output of the non-inverting amplifier circuit 44. ing. Further, the control circuit 13 includes timer latch circuits 143 and 144 connected to the outputs of the comparators 141 and 142, and a NOR (negative logical sum) connected between the outputs of the timer latch circuits 143 and 144 and the first AND circuit 130. ) Circuit 145.

  In the non-inverting amplifier circuit 44, a parallel circuit of a capacitor C14 and a resistor R16 is connected between the inverting input and the output of the operational amplifier 139, and the inverting input of the operational amplifier 139 is connected to the ground via the resistor R18. Further, the first output terminal 31 is connected to the non-inverting input of the operational amplifier 139 via the resistor R 17, and the output of the operational amplifier 139 is connected to the inverting inputs of the comparators 140 and 142 and the non-inverting input of the comparator 141. As a result, the non-inverting amplifier circuit 44 amplifies the potential (output voltage) of the first output terminal 31 on the high potential side of the power supply device 1 and outputs it to the comparators 140, 141, and 142.

  When the reference voltage Vref3 is applied to the non-inverting input and the output is input to the first AND circuit 130, the comparator 140 exceeds the reference voltage Vref3 when the output of the non-inverting amplifier circuit 44 (the detected value of the output voltage) exceeds the reference voltage Vref3. The output to the first AND circuit 130 is set to L level. The comparator 140 is designed to protect the circuit from the abnormal voltage because the output voltage becomes abnormally high when, for example, the power supply device 1 operates in an unloaded and open state where the light source load 30 is not connected to the output. Is provided. That is, in the power supply device 1, when the output voltage becomes larger than a predetermined threshold (determined by the reference voltage Vref3), the comparator 140 outputs an L level signal to the AND circuit 130 to turn off the switching element S1. Stop the switching operation. Thus, since the power supply device 1 stops the operation of the switching element S1 when the output voltage exceeds the predetermined threshold, the open circuit voltage can be controlled. This circuit is also effective when the light source load 30 itself has an open failure.

  Further, the reference voltage Vref4 is applied to the inverting input of the comparator 141. When the output of the non-inverting amplifier circuit 44 (the detected value of the output voltage) falls below the reference voltage Vref4, the output to the timer latch circuit 143 is set to the L level. And The timer latch circuit 143 changes the output from the L level to the H level and outputs it to the NOR circuit 145 when the signal from the comparator 141 continues to be at the H level for a predetermined time. At this time, since the NOR circuit 145 outputs an L level signal to the first AND circuit 130, the switching element S1 is turned off. That is, the power supply device 1 protects the circuit by completely stopping the switching element S1 by the comparator 141 and the timer latch circuit 143 when the state where the output voltage is continuously generated due to the output being released or the like occurs.

  The comparator 142 is applied with the reference voltage Vref5 at the non-inverting input. When the output of the non-inverting amplifier circuit 44 (the detected value of the output voltage) exceeds the reference voltage Vref5, the output to the timer latch circuit 144 is set to L. Level. When the signal from the comparator 142 continues to be at the H level for a predetermined time, the timer latch circuit 144 changes the output from the L level to the H level and outputs it to the NOR circuit 145. That is, when the output voltage is continuously low due to a short circuit between the output terminals 31 and 32 or the light source load 30, the power supply device 1 completely stops the switching element S1 by the comparator 142 and the timer latch circuit 144. Protect. The latch state of timer latch circuit 143.144 is canceled by temporarily turning off the power input to power supply device 1, for example (power reset).

  According to the power supply device 1 of the present embodiment described above, the control circuit 13 enables voltage control when the output is opened, and circuit protection when the output open state and the output short-circuit state continuously occur. The power supply device 1 according to the present embodiment has an advantage that various abnormalities can be detected more reliably by combining these circuit protection functions with a function for detecting an abnormality such as a ground fault or a power fault. .

  By the way, the lighting device using the power supply device 1 of the present embodiment is used for a lamp such as a headlamp (headlight) for a vehicle. For example, as illustrated in FIG. 11, the headlamp 100 includes a light source load 30, an optical unit 101 disposed in front of the light source load 30 (left side in FIG. 11), and a lighting device that supplies lighting power to the light source load 30. (Power supply device) 10 is provided in the lamp body 102 as a main component.

  The lighting device 10 and the light source load 30 are electrically connected by an output line 103, and lighting power is supplied to the light source load 30 via the output line 103. In addition, a heat radiating plate 104 is attached to the light source load 30, and heat generated by the light source load 30 is radiated to the outside by the heat radiating plate 104. Furthermore, the optical unit 101 controls the light distribution of the light emitted from the light source load 30. The lighting device 10 is attached to the lower surface of the lamp body 102, and is supplied with power from a vehicle-mounted battery (not shown) as a DC power source 2 provided in the vehicle via a power line 105. The light source unit including the light source load 30, the optical unit 101, the heat radiating plate 104, and the like is attached to the lamp body 102 by a fixture 106.

  Here, the heat radiating plate 104 may be connected to the ground of the vehicle-mounted battery of the vehicle or the casing of the lighting device 10 for fixing and noise countermeasures. In this configuration, an abnormality (ground fault) may occur in the output of the power supply device (lighting device 10) 1 due to some accident. Even when such an abnormality occurs, the switching operation can be stopped by turning off the switching element S1 of the power supply device 1 by using the power supply device 1 according to the present embodiment.

  FIG. 12 is an external perspective view of a vehicle 107 on which a pair of the headlamps 100 described above are mounted on the left and right. In this vehicle 107, even if the wiring is cut off or the wiring coating is peeled off due to incomplete wiring or the like, even if a ground fault or a power fault occurs in the output (output terminals 31 and 32) of the power supply device 1, The switching operation can be stopped by turning off the switching element S1. The lamp is not limited to the headlamp 100, and may be a turn indicator or tail lamp of the vehicle 107, or other lamps.

  By the way, in this embodiment, although the light source load 30 showed the example comprised by the two LED modules 301 and 302, the number of LED modules which comprise the light source load 30 is not restricted to two, but one or three It may be more than one. Further, the control circuit 13 uses proportional-integral control by the error calculation circuit 42 as a method of constant current control of output, but other constant current control methods may be used. Further, the control circuit 13 may be configured using a microcomputer or the like, and the feedback control unit may be configured digitally. In this embodiment, the power supply device 1 that controls the output current to a constant value (constant current control) has been described as an example. However, the power supply device 1 has a configuration that controls the output voltage to a constant value (constant voltage control). There may be.

  Further, the power supply device 1 applied to the lighting device 10 is not limited to the configuration of FIG. 8 provided with the first resistor R1, but as described in the first embodiment, the power supply device 1 having a configuration without the first resistor R1. It may be.

  Other configurations and functions are the same as those of the first embodiment.

DESCRIPTION OF SYMBOLS 1 Power supply device 2 DC power supply 3 Load 10 Lighting device 13 Control circuit 21, 22 Input end 30 Light source load 31, 32 Output end 41 Differential amplifier circuit (current measurement part)
100 headlights
102 Lamp 107 Vehicle C1 First Capacitor C2 Second Capacitor D1 Diode (Rectifier)
L1 first inductor L2 second inductor R1 first resistor R2 second resistor (detection resistor)
S1 switching element

Claims (7)

A series circuit of a switching element and a first inductor that are alternately turned on and off alternately, and connected between a pair of input terminals to which a DC power supply is connected so that the switching element is on the positive side of the DC power supply A first series circuit;
A second series circuit comprising a series circuit of a second inductor and a rectifying element, the second inductor being connected between a pair of output terminals to which a load is connected, so that the second inductor is on the cathode side of the rectifying element;
A first capacitor connected between one end of the first inductor, which is a connection point with the switching element, and a cathode of the rectifying element;
A second capacitor connected between the anode of the other end and said rectifying element of said first inductor,
A power supply apparatus comprising: a resistor connected in parallel with the second capacitor .   A series circuit of a switching element and a first inductor that are alternately turned on and off alternately, and connected between a pair of input terminals to which a DC power supply is connected so that the switching element is on the positive side of the DC power supply A first series circuit;
  A second series circuit comprising a series circuit of a second inductor and a rectifying element, the second inductor being connected between a pair of output terminals to which a load is connected, so that the second inductor is on the cathode side of the rectifying element;
  A first capacitor connected between one end of the first inductor, which is a connection point with the switching element, and a cathode of the rectifying element;
  A second capacitor connected between the other end of the first inductor and the anode of the rectifying element;
  The power supply device, wherein the second capacitor has a larger capacity than the first capacitor.   A series circuit of a switching element and a first inductor that are alternately turned on and off alternately, and connected between a pair of input terminals to which a DC power supply is connected so that the switching element is on the positive side of the DC power supply A first series circuit;
  A second series circuit comprising a series circuit of a second inductor and a rectifying element, the second inductor being connected between a pair of output terminals to which a load is connected, so that the second inductor is on the cathode side of the rectifying element;
  A first capacitor connected between one end of the first inductor, which is a connection point with the switching element, and a cathode of the rectifying element;
  A second capacitor connected between the other end of the first inductor and the anode of the rectifying element;
  A control circuit for controlling the switching operation of the switching element,
  The control circuit monitors a potential at a connection point between the second capacitor and the rectifying element, and stops the switching operation of the switching element when the potential falls below a predetermined threshold.   A series circuit of a switching element and a first inductor that are alternately turned on and off alternately, and connected between a pair of input terminals to which a DC power supply is connected so that the switching element is on the positive side of the DC power supply A first series circuit;
  A second series circuit comprising a series circuit of a second inductor and a rectifying element, the second inductor being connected between a pair of output terminals to which a load is connected, so that the second inductor is on the cathode side of the rectifying element;
  A first capacitor connected between one end of the first inductor, which is a connection point with the switching element, and a cathode of the rectifying element;
  A second capacitor connected between the other end of the first inductor and the anode of the rectifying element;
  A control circuit for controlling the switching operation of the switching element;
  The magnitude of the output current flowing from the output terminal to the load is measured by monitoring the voltage across the detection resistor inserted between the connection point of the rectifying element and the output terminal of the second capacitor. A current measuring unit that
  The control circuit controls the switching element so that a measurement value of the current measurement unit becomes a predetermined reference value, and a potential at a connection point between the second capacitor and the rectifying element has a predetermined threshold value. The power supply device is characterized in that when the period of time below continues for a predetermined time, the switching operation of the switching element is stopped.   5. The power supply device according to claim 1, wherein a light source load using a semiconductor light emitting element is connected to the output terminal as the load, and the light source load is supplied by supplying power to the light source load. A lighting device characterized by lighting.   A lamp comprising the lighting device according to claim 5 in a lamp body.   A vehicle comprising the lamp according to claim 6.

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